Syndrome


Fig. 10.1

A model of potential contribution of different factors in SS pathogenesis




Table 10.1

Association of non-MHC class genes with SS susceptibility according to distinct pathogenetic pathways



































 

Type I and II IFN pathways


B-cell activation


NF-κΒ


Genes/chromosomes


IRF5/Chr7


BLK-FAM167A/Chr8


TNFAIP3/chr6


IRF5/TNPO3/Chr7


CXCR5/Chr11


TNIP1/Chr5


STAT4/Chr2


BAFF/Chr13


LTA/LTB/TNF gene clusters


IL12Α/Chr3


GTF2I/chr7


BAFF-R/Chr22


NCR3/NKp30/Chr6


EBF1/Chr5

 


IRF5 interferon regulatory factor 5; TNPO3 transportin 3; STAT4 signal transducer and activator of transcription 4; IL12Α interleukin 12A; NCR3/NKp30 natural cytotoxicity triggering receptor 3/natural killer protein 30; BLK-FAM167A B-lymphocyte kinase/family with sequence similarity 167, member A; CXCR5 chemokine (C-X-C motif) receptor 5; BAFF B-cell activating factor; GTF2I general transcription factor 2I; EBF1 early B-cell factor 1; TNFAIP3 tumor necrosis factor-alpha-induced protein 3; TNIP1 TNFAIP3-interacting protein 1; LTA/LTB/TNF lymphotoxin gene A, lymphotoxin gene B, tumor necrosis factor; BAFF-R B-cell activating factor receptor



The observation that lymphocytes infiltrating exocrine glands and parenchymal organs surround epithelia suggests a central role of the epithelial cell in the formation and further organization of characteristic immunopathological lesions in SS [29]. Especially, salivary gland epithelial cells have been investigated and found to undergo increased apoptosis [30], leading to release of autoantigens (such as Ro/SSA and La/SSB) which in turn drive the production of disease-specific autoantibodies. The immunocomplexes that are generated through this process result in type I interferon (IFN) production by plasmacytoid dendritic cells (PDCs) in individuals with genetic predisposition. Subsequently, type I IFN can reinforce epithelial activation and BAFF overexpression, as well as autoantibody production. The complex role of activated epithelia as antigen-presenting cells and cells secreting chemokines and cytokines or expressing chemotactic molecules places them at the center of the immunological process. Epithelial cells ultimately contribute to further aggregation of inflammatory cells, activation of lymphocytes (both T and B), and autoantibody production, thus closing the vicious circle of autoimmunity. This series of events can possibly culminate in extensive tissue damage and even B-cell monoclonal expansion [4, 3135]. Therefore, the term “autoimmune epithelitis,” stressing the key role and active involvement of epithelial cells, has been fairly proposed to describe SS [36].


Diagnosis and Differential Diagnosis


Thorough patient history and meticulous clinical examination of all systems are of utmost importance [10]. Family history should also be recorded, as familial clustering of cases with SS and other autoimmune conditions has been recorded [2025]. Classification criteria are commonly used in order to establish SS diagnosis, with the latest revision having taken place in 2016 by the American/European Consensus Group (Table 10.2) [37]. Differential diagnosis is summarized schematically in Table 10.3 [3741].


Table 10.2

2016 American College of Rheumatology/European League Against Rheumatism classification criteria for primary SS. The classification of pSS applies to any individual who meets the inclusion criteria (a), does not have any of the conditions listed as exclusion criteria (b), and has a score of at least 4 when the weights from the five selected criteria items are summed (c). Several changes from 2002 AECG classification criteria were made. Subjective ocular or oral symptoms are now considered a prerequisite, rather than criteria contributing to the total score as they were before. Sialography and scintigraphy have been omitted, and a higher threshold for the ocular staining score has been implemented. The list of exclusion criteria was revisited, as the newly identified IgG4-related disease was added and lymphoma was removed, while more accurate techniques are required to rule out known, confounding entities (PCR confirmation of active hepatitis C). Finally, anti-SSB/La autoantibodies positivity was concluded to have no diagnostic value in the absence of anti-SSA/Ro and was therefore withdrawn. To be noted that patients on anticholinergic drugs should be objectively evaluated for their sicca symptoms after a sufficient time of these medications has elapsed

























(a) Inclusion criteria


Positive response to at least 1 of the following questions:


1. Have you had daily, persistent, troublesome dry eyes for more than 3 months?


2. Do you have a recurrent sensation of sand or gravel in the eyes?


3. Do you use tear substitutes more than 3 times a day?


4. Have you had a daily feeling of dry mouth for more than 3 months?


5. Do you frequently drink liquids to aid in swallowing dry food?


or


Suspicion of Sjögren’s syndrome from the ESSDAI questionnaire (at least 1 domain with a positive item)












(b) Exclusion criteria


1. History of head and neck radiation treatment


2. Active hepatitis C infection


3. AIDS


4. Sarcoidosis


5. Amyloidosis


6. Graft-versus-host disease


7. IgG4-related disease































(c)


Criteria items


Weighted score


SS classification


Labial salivary gland with focal lymphocytic sialadenitis and focus score ≥ 1 foci/4 mm2


3


Score ≥ 4


Anti-Ro/SSA positivity


3


Ocular staining score ≥ 5 (or van Bijsterveld score ≥ 4) in at least one eye


1


Positive Schirmer’s test (≤5 mm/5 min in at least one eye)


1


Unstimulated whole saliva flow rate ≤ 0.1 ml/min


1




Table 10.3

SS differential diagnosis. Other causes of sicca symptoms and processes infiltrating the exocrine glands need to be ruled out in order to reach the correct diagnosis. IgG4-related disease is a newly identified entity, added in the exclusion criteria list of the recently reviewed American/European Consensus SS classification criteria. It is a multi-organ, immune-mediated condition that has unified several diseases once considered to be individual. It includes Mikulicz disease (sialo/dacryo-adenitis and salivary/lacrimal gland enlargement), Küttner tumor, Riedel’s thyroiditis, orbital inflammatory pseudotumor, pituitary hypophysitis, and hypertrophic pachymeningitis in the head and neck region, as well as autoimmune pancreatitis, interstitial pneumonitis, interstitial nephritis, prostatitis, retroperitoneal fibrosis, and inflammatory aortic aneurysm. Elevated serum IgG4 levels (≥135 mg/dl) and infiltration of abundant IgG4-positive plasma cells into affected organs help with differential diagnosis

















Sicca symptoms (xerophthalmia and/or xerostomia)


Lymphocytic infiltration of exocrine glands


Non-lymphocytic infiltration of exocrine glands


Use of medications


Antihypertensives, antihistamines, antidepressants, isotretinoin, etc.


Previous head and neck radiation


Diabetes mellitus


Vitamin A deficiency


Any functional or anatomical defect of the eyelid


Chronic blepharitis, chronic conjunctivitis, or another chronic eye inflammation


Psychogenic


Chronic viral infections


Hepatitis C, AIDS, HTLV-1


IgG4-related disease


Chronic graft-versus-host disease


Lymphoma


Granulomatous diseases


Sarcoidosis, tuberculosis, leprosy, syphilis


Metabolic infiltration


Hyperlipoproteinemia, diabetes mellitus, amyloidosis, hemochromatosis


Diagnostic Tests


Laboratory Tests


Routine laboratory tests (full blood count, renal and liver function tests, serum protein electrophoresis plus immunofixation in case of hypergammaglobulinemia, erythrocyte sedimentation rate, C-reactive protein, urine analysis) and immunologic markers (rheumatoid factor, anti-nuclear antibodies, complement levels, antibodies against the cytoplasmic antigens SSA/Ro and SSB/La, cryoglobulins, anti-thyroid autoantibodies) are included in the laboratory evaluation of suspected SS [4244]. Testing for viruses (HCV, HIV, HTLV-1) and IgG4 levels is carried out for differential diagnosis purposes, and other targeted autoantibodies or supplementary laboratory tests can be requested, according to specific clinical manifestations [3846]. A schematic presentation of associations between specific autoantibodies detected in SS patients and disease phenotypical characteristics is shown in Table 10.4 [4663].


Table 10.4

Prevalence of specific autoantibodies in SS patients and correlation with clinical manifestations, other serological features, and disease outcomes. This table includes traditional autoantibodies for disease classification, autoantibodies identified from murine models, and autoantibodies typically associated with other autoimmune diseases. The hoped-for result of as early as possible diagnosis has recently led to the marketing of a new diagnostic kit (Sjö® test). The cumulative sensitivity of traditional (ANA, RF, anti-SSA/Ro, anti-SSB/La) and novel (anti-CA VI, anti-SP-1, anti-PSP) antibodies of Sjö® panel has been estimated to be 91.8%, whereas the sensitivities for anti-SSA/SSB alone and for the novel biomarkers alone were found to be 74.9% and 49.8%, respectively. Additionally, the cumulative specificity for the complete Sjö® panel was estimated at 79.8%. Further potential biomarkers currently under investigation are anti-kallikrein antibodies, antibodies against carbamylated proteins, and antibodies against TRIM38 proteins, among others (not shown in the table)













































































Type of autoantibodies


Prevalence of autoantibody positivity in pSS patients


Clinical correlation/significance


Anti-Ro/SSA


Anti-La/SSB


33–74%


23–52%


Usually associated with female sex, younger age at diagnosis, more prominent lymphocytic infiltrate of the exocrine glands, and potentially a higher prevalence of extraglandular manifestations


Attention needed in case of pregnancy, due to potential congenital heart block of the baby (complete heart block occurring in approximately 2% of cases)


Anti-nuclear antibodies (ANA)


59–85%


Associated with female gender, younger age at diagnosis, parotid gland enlargement, extraglandular manifestations, cytopenia, hypergammaglobulinemia, as well as increased frequency of RF, anti-Ro/SSA, anti-La/SSB, and antiphospholipid antibodies positivity


Rheumatoid factor (RF)


36–74%


Linked to earlier disease onset, female predominance, positive salivary gland biopsy, more frequent extraglandular features, and higher use of corticosteroids, among others


Also, increased frequency of anti-La/SSB, anti-Ro/SSA, cryoglobulins, and ANA positivity, as well as low C3/C4 and hypergammaglobulinemia


Cryoglobulins


9–15%


One of the indisputable risk factors for non-Hodgkin’s lymphoma development and SS-related death. Also, linked to earlier disease onset, higher frequency of extraglandular features (vasculitis, renal involvement, peripheral neuropathy, Raynaud’s phenomenon) and cytopenia, as well as higher prevalence of parotid gland enlargement


Anti-thyroperoxidase antibodies (anti-TPO)


Anti-thyroglobulin antibodies (anti-TG)


11–45%


3–100%


Autoimmune thyroid disease prevalence in SS seems to be 10–30%


Furthermore, SS prevalence in already diagnosed autoimmune thyroid disease has been reported to be 3–32% (10 times higher probability of SS in autoimmune thyroid disease than in the general population)


Sicca symptoms are even more frequent in the context of autoimmune thyroid disease (37% of patients develop xerostomia and 23% isolated keratoconjunctivitis sicca)


Autoimmune thyroid disease-associated SS is linked to milder SS phenotype, but also to greater risk of developing further autoimmune diseases (such as autoimmune liver and inflammatory bowel diseases), requiring closer follow-up


Antibodies against cyclic citrullinated peptides (anti-CCP)


3–10%


Anti-CCP-positive pSS patients do not seem to have major clinical differences from anti-CCP-negative individuals, but there is a possible association with nonerosive arthritis


Anti-mitochondrial antibodies (AMA)


1.7–27%


Depending on laboratory technique for detection; indirect immunofluorescence, Western blot, or ELISA


Specific for primary biliary cirrhosis (PBC)


Also, higher prevalence of Raynaud’s phenomenon, peripheral neuropathy, hypergammaglobulinemia, and high ESR


Valuable for separating patients with autoimmune liver involvement from those with chronic viral liver disease


Anti-smooth muscle antibodies (ASMA)


30–62%


Autoimmune hepatitis (only 1.7–4% in pSS patients)


Anti-centromere antibodies (ACA, comprising of CENP-A, CENP-B, and CENP-C)


3.7–27%


Overlapping features between SS and systemic sclerosis (SSc)


Up to 40% of the ACA-positive pSS patients can progress to systemic sclerosis


Associated with delayed disease onset, but increased frequency of keratoconjunctivitis sicca, Raynaud’s phenomenon, peripheral neuropathy, and lymphoma


Lower frequency of anti-Ro/La antibodies and higher prevalence of other coexisting autoimmune disorders, such as PBC


SS patients usually recognize CENP-C alone, whereas recognition of both CENP-B and CENP-C is more frequent in SSc


Antibodies against carbonic anhydrase (anti-CA; 13 known isoenzymes)


12.5–20.8%


Anti-CA II antibodies linked to renal involvement and particularly distal renal tubular acidosis


Anti-CA VI and anti-CA XIII antibodies have also been shown to correlate with urine pH and inversely with serum sodium levels (cross-reactivity between anti-CA VI and anti-CA XIII is a possible scenario, as CA VI is the only isoenzyme secreted in saliva and expressed in the parotid and submandibular glands, but not in the kidney)


Anti-CA VI is considered a novel, early SS biomarker, included in commercially available Sjö® diagnostic panel. It is the most prevalent novel autoantibody of the kit among both SS and non-SS dry eye patients (52% and 43%, respectively). Anti-CA VI positivity has been linked to more severe xerophthalmia, presence of xerostomia, younger age, and negative MSGB


Antibodies to 21-hydroxylase (anti-21[OH])


17.50%


Anti-21[OH] positivity was not linked to overt adrenal insufficiency, but it was associated with adrenal hyporesponsiveness and evidence of more prominent B-cell activation in MSG tissue samples


Decreased prevalence of subjective xerophthalmia and increased frequency of leukopenia were also noted for anti-21[OH]-positive SS individuals


Anti-muscarinic receptor antibodies


62.2–81.8%


Associated with cytopenia and higher ESSDAI scores


Could partially account for the salivary gland hypofunction, the gastroesophageal symptoms, and the bladder smooth muscle hyperresponsiveness, observed in pSS patients


Antibodies against citrullinated alpha-enolase peptides (anti- CEP-1)


60% of anti-citrullinated protein antibodies (ACPA)-positive pSS patients


Less than 10% of unselected pSS patients


Associated with higher urine pH levels at first evaluation


(linked to distal renal tubular acidosis, nephrocalcinosis, and impaired bone health)


Antibodies against salivary protein 1 (anti-SP-1)


52% of SS patients


19% of SS patients with negative anti-Ro/anti-La


Antibodies against murine SP-1 (no known human protein analogue) seem to identify targets in human parotid glands


Anti-SP-1 antibodies are considered novel, early SS biomarkers, included in commercially available Sjö® diagnostic panel


Patients with lower focus scores in MSGB tend to be tested positive for anti-SP-1 more often than those with higher focus scores (who generally test positive for anti-Ro/anti-La). Especially patients expressing only anti-SP-1 antibodies (no anti-Ro/anti-La) have low or negative MSGB focus score


Anti-SP-1 can also be used as a marker to separate SS-associated RA from RA not complicated with SS


Antibodies against parotid secretory protein (anti-PSP)


18%


PSP is a protein involved in the binding and clearance of infectious agents


Anti-PSP is considered a novel, early SS biomarker, included in commercially available Sjö® diagnostic panel


Can also be positive in non-SS dry eye disease and rarely in RA and healthy controls


Anti-α-fodrin antibodies


29% of pSS patients, but 47% of SLE patients


Almost 2 times more prevalent in non-SS sicca than SS patients


Anti-α-fodrin antibodies serum concentrations have been associated with the degree of lymphocytic infiltration in salivary glands


Usually found in early disease stages


Most probably not useful for SS diagnostic purposes


Salivary Gland Biopsy


Minor salivary gland biopsy (MSGB) (Fig. 10.2) displays a crucial role for diagnosis, prognosis, and risk stratification [64, 65]. According to American/European Consensus SS classification criteria of 2016, diagnosis cannot be established without a positive MSGB or positive anti-SSA/Ro antibodies [37]. Moreover, intense lymphocytic infiltration has been identified as an independent histopathological risk factor for NHL development [66], which is the leading cause of excess mortality in SS patients [6769].

../images/464721_1_En_10_Chapter/464721_1_En_10_Fig2_HTML.jpg

Fig. 10.2

Minor salivary gland (labial) biopsy. The procedure is simple and well-tolerated and can be done under local anesthesia on an outpatient basis. Usually 4–6 minor salivary gland lobules need to be sampled, in order for the tissue to be considered representative. Several different surgical approaches have been suggested in an effort to minimize complications. Most frequent adverse events reported in literature include temporary localized pain and bleeding, and only rarely there have been cases with persistent hypoesthesia of the lower lip (Photograph courtesy of E. Piperi, Assistant Professor in Department of Oral Pathology, School of Dentistry, UoA)


The presence of a lymphocytic infiltrate of ≥50 lymphocytes per 4 mm2 of glandular parenchyma, usually located in the periductal area, is considered a positive focus score. The average number of these lymphocytic aggregates per 4 mm2 of salivary gland tissue is the focus score (Fig. 10.3) [64]. Despite the fact that only focus score appears in the American/European consensus criteria, Tarpley score (measure of glandular architecture derangement) is also commonly used [65, 70]. Another important histopathological feature is the presence of germinal center (GC)-like structures (Fig. 10.4). The latter have been associated with higher focus score, higher frequency of extraglandular manifestations, hypergammaglobulinemia, increased RF levels, and higher prevalence of positive anti-SSA/Ro and/or anti-SSB/La autoantibodies. The presence of GC-like structures has also been suggested to confer increased risk for lymphoma development. However, the contradicting results on GC-like structures significance from various studies – possibly due to poor definition on one hand and under-detection in H&E staining on the other – underline the need for uniform criteria and further research [65, 7073].

../images/464721_1_En_10_Chapter/464721_1_En_10_Fig3_HTML.jpg

Fig. 10.3

Minor salivary gland biopsy with high focus score (Hematoxylin & Eosin staining)


../images/464721_1_En_10_Chapter/464721_1_En_10_Fig4_HTML.png

Fig. 10.4

Minor salivary gland biopsy with MALT development and germinal center-like formation in ×100 (a) and ×200 (b) magnification (Hematoxylin & Eosin staining). GC-like structures are tertiary ectopic lymphoid structures, and they are considered an advanced histopathologic lesion, previously correlated with future lymphomagenesis, extraglandular manifestations, and earlier diagnosis. However, their role in lymphomagenesis is still questioned, since more recent research has failed to demonstrate such a correlation. The prevalence of GC-like structures in SS patients is ranging from 18% to 59% according to different studies


The advantages of MSGB include easy accessibility, avoidance of skin incisions, and local anesthesia. Parotid biopsy is reserved only to rule out lymphoma in case of persistent parotid enlargement [74, 75]. MSGB sensitivity and specificity are considered to be higher than 75% and 90%, respectively [64, 76, 77].


Oral Involvement Assessment Tests


The objective evaluation of xerostomia and oral involvement in SS, except for the generally accepted MSGB, remains a challenge [75, 78]. The easiest, most common, and affordable way to assess major and minor salivary gland secretory capacity is the measurement of salivary flow or sialometry. Unstimulated whole saliva flow rate equal to or below 0.1 ml/min is considered abnormal (0.3–0.4 ml/min are expected for healthy individuals) [75].


Sialography may be used to demonstrate the morphology of the ducts, while scintigraphy can assess the salivary gland functionality. The nonspecific results of both techniques and the involvement of radiation for the latter have led to their removal from the most recent SS classification criteria [75, 79].


Ultrasound (US), being noninvasive, inexpensive, and radiation-free, is drawing a lot of attention for the purposes of major salivary gland imaging. Multiple studies have shown good agreement and comparable results between salivary gland ultrasound and sialography and even diagnostic superiority compared to scintigraphy [80].


In addition to its value as a diagnostic tool, the prognostic value of ultrasound has also been explored. Increased parenchymal dyshomogeneity scores of major salivary glands have been found to correlate with SSA, SSB, ANA, RF, higher levels of IgG, salivary gland enlargement, cutaneous vasculitis and/or purpura, GC-like structures in salivary gland biopsy, CD4 T-cell lymphopenia, Raynaud’s phenomenon, and disease activity scores. Last but not least, there is some evidence that ultrasonographic images of salivary glands change in response to treatment (rituximab versus placebo) for SS [80].


Elastography is an added feature to the classic US modality, which can increase sensitivity compared to B-mode US alone and differentiate between SS patients and sicca controls [81].


Ocular Tests


Mainly aqueous deficiency but also meibomian gland dysfunction and neuropathic pain contribute to increased tear evaporation rate, reduced tear film stability, and ocular discomfort in SS patients [82].


Keratoconjunctivitis sicca (KCS) symptoms can be quantified using patient questionnaires, like the Ocular Surface Disease Index (OSDI). The main available objective tests are Schirmer’s test (Fig. 10.5), ocular surface dye staining (Fig. 10.6), and tear breakup time (TBUT) [8284]. Among those, only the first two are included in the latest classification criteria [37].

../images/464721_1_En_10_Chapter/464721_1_En_10_Fig5_HTML.jpg

Fig. 10.5

Schirmer’s test involves the measured wetting of a standardized paper strip, placed over the inferior eyelid, over a certain period of time. It is usually performed without anesthesia, and the test is considered positive when at most 5 mm of the paper are wetted in 5 min time. The cutoff point is lower (<3 mm) when the test is performed under anesthesia, as in this case we measure the basal/non-reflex tear production (Permission to re-produce kindly granted by Messmer [40])


../images/464721_1_En_10_Chapter/464721_1_En_10_Fig6_HTML.jpg

Fig. 10.6

Staining of the ocular surface in dry eye disease. Fluorescein better stains the cornea (a), while lissamine green (LG) is preferred for the conjunctiva (b). LG tends to be used nowadays instead of rose bengal (RB), due to improved toxicity and tolerance profile, given their similar staining properties. Both RB and LG bind to corneal epithelial cells that are uncoated by mucin or other proteins, and these damaged areas are easily observed under slit lamp examination. However, both dyes seem to correlate poorly to symptom severity as stated by patients in relevant questionnaires (Permission to re-produce kindly granted by Messmer [40])


Disease Activity Indexes


There are two indexes, introduced by European League Against Rheumatism (EULAR), which are used to assess SS activity from the patient’s and the clinician’s point of view. The first one is the EULAR Sjögren’s Syndrome Patient Report Index (ESSPRI), which consists of three visual-analogue scales measuring severity of sicca symptoms, fatigue, and pain [85]. The second one is the EULAR Sjögren’s Syndrome Disease Activity Index (ESSDAI), which assesses the activity in 12 different domains representing organ systems. Since its introduction, ESSDAI has become the gold standard in terms of disease activity assessment because it serves as point of reference among physicians; it is widely used in randomized controlled trials as outcome measure and has been correlated with biomarkers and lymphoma development risk [42, 43].


Clinical Manifestations and Disease Management


SS can manifest with a plethora of clinical signs and symptoms, frequently vague and definitely not pathognomonic, often resulting in diagnostic delays [86]. Oral and ocular dryness, sometimes accompanied by xeroderma, upper respiratory desiccation, and vaginal dryness with subsequent dyspareunia are among the most common complaints [10]. Extraglandular manifestations (Fig. 10.7) occur in at least one third of individuals and can schematically be divided into three groups: nonspecific, periepithelial, and immune complexes mediated [6, 8794]. The disease often runs a benign, indolent course with the exception of severe systemic complications causing excess morbidity and most importantly lymphoma, which is one of the main causes of mortality in SS [42, 67].

../images/464721_1_En_10_Chapter/464721_1_En_10_Fig7_HTML.jpg

Fig. 10.7

Extraglandular features of SS. Top left: Palpable purpura in the lower extremities. Top right: Multiple necrotic cutaneous ulcers of the lower extremities in a patient with SS and cryoglobulinemia. Bottom: Annular urticarial lesions of the trunk (Permission to re-produce kindly granted by Hile et al. [148])


With regard to management, pilocarpine is usually initiated in an effort to alleviate ocular discomfort and difficulty in everyday life caused by lack of saliva, but residual lacrimal and salivary gland function is a prerequisite in order to be effective [95, 96]. SS patients must be informed on the rare side effects of pilocarpine, such as excessive sweating, nausea, diarrhea, and palpitations; for this reason, progressive dose escalation is recommended. Natural tears and lubricants for ocular use, as well as artificial saliva and oral solutions with chlorhexidine, are frequently used by patients and recommended by ophthalmologists and dentists, respectively [97]. Interestingly, in contrast to other systemic autoimmune diseases with high inflammatory load, SS-related sicca complaints do not respond to immunosuppressive treatment [98]. Mild aerobic exercise is recommended for fatigue [99], while disease-modifying antirheumatic drugs (DMARDs) are reserved for extraglandular manifestations [100103]. The rare cases of aggressive lymphomas are managed with cytotoxic drugs [104106]. Tables 10.5 and 10.6 display the array of clinical manifestations and the recommended treatment options in SS patients [107120].


Table 10.5

Glandular manifestations and their treatment in SS patients





























Organ involvement


Symptoms and signs


Therapeutic approach


Ocular


Irregularity of the corneal image, irritation, redness, photosensitivity


No MG damage (aqueous deficiency)


Stop offending drugs, environmental changes, artificial tears, gels, ointments


Ω3 suppl., CIS collyrium (0.05%) pulse steroids, punctal plugs, secretagogues, moisture chamber spectacles


Topical autologous serum, contact lenses, permanent punctal occlusion


Systemic anti-inflammatory medication, eyelid surgery


MG damage (evaporative)


Stop offending drugs, environment modification, lipid-rich tear substitutes, warm compress, massage


CIS: 2–2.5 mg/kg/d, topical steroids, AZI, DXC, secretagogues, punctal plugs, moisture chamber spectacles


Topical autologous serum, contact lenses


Eyelid surgery


Oral


Dryness, caries, angular cheilitis


Salivary gland enlargement


Dental fluorination, masticatory stimulation, chlorhexidine


Pilocarpine hydrochloride: max 20 mg/d in divided doses


Cevimeline hydrochloride: max 30 mg × 3


CS, 0.25–0.5 mg/kg/d for 10–15 d


Pancreatic


Recurrent autoimmune pancreatitis (5%)


AZA 2–3 mg/kg/d, RTX, pancreatic enzymes


Vaginal


Dyspareunia


Lubricants



MG meibomian gland, CIS cyclosporine, AZI azithromycin, DXC doxycycline, CS corticosteroids




Table 10.6

Extraglandular manifestations and their treatment in SS patients



























































Organ involvement


Symptoms and signs


Therapeutic approach


Nonspecific


Musculoskeletal


Myalgias, arthralgias, Jaccoud arthropathy, rare arthritis


HCQ, MTX, or combination of both, small dose CS < 15mg qd


Raynaud’s phenomenon


Cold-related color skin changes


Vasodilators, especially calcium channel blockers


Fatigue (35–50%)


Increased need for resting hours, disruption of sleep patterns


Nordic (active) walking, HCQ in some cases


RTX


Periepithelial


Bronchi (10–20%)


Small airway disease (13%)


ILD (17%)


Mild to moderate dyspnea and dry cough, xerotrachea


Bronchodilators


AZA, RTX


Autoimmune cholangitis


LFTs abnormalities, jaundice


RTX


UDCA, AZA


Renal/bladder (4–30%)


Tubulo-interstitial nephritis


Interstitial cystitis (0.3%)


Hypokalemic hyperchloremic distal renal tubular acidosis/nephrocalcinosis


Pollakiuria, nycturia, urinary urgency, pelvic or suprapubic pain


Urine alkalization (bicarbonate, electrolyte supplements)


CS


CS, CIS, surgical intervention


Immune complex-mediated disease


Skin vasculitis


Vasculitis in 5%


Purpura – palpable in 5%


Annular erythema


Cryoglobulinemia


CYC, AZA


RTX for necrotizing vasculitis (cycles of 2gr q15 days interval/6 months)


Glomerulonephritis(rare)


Membranous or membranoproliferative


CS, RTX, CYC


Neuropathy (20%)


Peripheral neuropathy


CNS


Peripheral sensorimotor neuropathy or pure sensory neuropathy


Motor neuropathy/ganglionopathy


Mononeuritis multiplex


Small fiber neuropathy


MS-like


CS, 0.5–1 mg/kg, and IVIGs, RTX


CS, 0.5–1 mg/kg, and CYC/AZA, 2–3 mg/kg/d


Anticholinergics, antidepressants, gabapentinoids


CS, PE, RTX


Low-grade lymphoma


Disseminated lymphoma

 

Wait and watch policy


R-CHOP = if diffuse large B cell



HCQ hydroxychloroquine (5 mg/kg qd), MTX methotrexate 2.5–3 mg/15 kg qw), CS corticosteroids, RTX rituximab (cycles of 2gr q15 days interval/6 months), AZA azathioprine (2–3 mg/kg qd), UDCA ursodesoxycholic acid, CIS cyclosporine (2–2.5 mg/kg qd), CYC cyclophosphamide (750 mg–1 g/m2), IVIGs intravenous immunoglobulins, R-CHOP rituximab-(c)yclophosphamide, (h)ydroxydaunorubicin, (o)ncovin (vincristine), (p)rednisone


Lymphomagenesis and Lymphoproliferation


SS is unique among autoimmune diseases as for malignant transformation risk. Those patients seem to have a 10–44-fold greater risk of developing lymphoma compared to general population, whereas systemic lupus erythematosus patients and rheumatoid arthritis patients only have a seven-fold and four-fold greater risk, respectively [67, 121]. In other words, 2.7–9.8% of SS patients are diagnosed with non-Hodgkin lymphoma (NHL) and that risk increases by 2.2% per year of age [78, 122].


Mucosa-associated lymphoid tissue (MALT) lymphomas represent 60% of cases [67]. Most common sites are the salivary glands, especially the parotid and submandibular glands, but other mucosal sites of MALT lymphoma development include the orbits, nasopharynx, stomach, thyroid, and lung [78]. Other subtypes of lymphoma found in these patients are the diffuse large B-cell lymphoma (DLBCL) and the nodal marginal zone lymphoma (NMZL), which – together with MALT – account for more than 90% of total SS-associated lymphoma cases [67].


Multiple research studies have been focusing their efforts on correlating clinical, serological, and histopathological features with risk of lymphomagenesis [66, 72, 123126], and an attempt has also been made to formulate a predictive score for SS-related NHL development based on data collected at the time of diagnosis [123] (Fig. 10.8). However, the molecular etiopathogenetic aspects of malignant transformation still remain largely elusive and ill-defined.

../images/464721_1_En_10_Chapter/464721_1_En_10_Fig8_HTML.png

Fig. 10.8

Risk factors for lymphomagenesis in SS, as identified by various studies over the last years and a predictive score formula based on seven of them. Relevant information is gathered at the time of disease diagnosis and correlates with disease outcome, even years later, leading to the conclusion that early risk stratification is feasible for those patients. SGE salivary gland enlargement


Current belief on etiopathogenesis of lymphoma focuses on four interrelated axes: chronic inflammation, B-cell activation, defective immunosurveillance, and epigenetic alterations [4, 104]. Focus score of at least 3 in MSGBs of SS patients has been identified as an independent and important predicting factor for NHL development, and the use of this threshold has a positive predictive value of 16% and a negative predictive value of 98% for that kind of malignant transformation [66]. Furthermore, the activation of P2X7 receptor-NLRP3 inflammasome complex (with subsequent increase of pro-inflammatory cytokines IL-18 and IL-1β serum levels, among others) correlates with lymphocytic infiltration severity, ESSDAI scores, and lymphoproliferation risk. The hypothesis of inflammasome activation secondary to increased accumulation of proinflammatory nucleic acid shreds, ineffectively degraded and cleared, has recently been supported [127, 128].


Another factor promoting chronic inflammation seems to be IFNγ, as the mRNA levels in MSGBs have been associated with a higher degree of lymphocytic infiltration, shown to be a predisposing factor for lymphomagenesis [129]. Moreover, a functional variant of TNFAIP3 gene (rs2230926), encoding the A20 protein, leads to unopposed NF-κB pathway activation and is therefore involved in inflammatory process perpetuation, B-cell survival, and more aggressive disease phenotype with earlier disease onset and increased lymphoproliferation risk [130].


B-cell activating factor (BAFF), produced by various immune cells but also by the salivary epithelial cells and regulated by both type I and II IFNs, is of utmost importance for the maturation, proliferation, and survival of B cells. BAFF levels are found increased in SS patients’ serum with a history of lymphoma, and high levels persist for years after treatment and remission [4, 131, 132]. Another equally important observation is the association of specific BAFF polymorphisms with SS-related lymphomagenesis and in particular the significantly different prevalence of the protective AA genotype of the rs12583006 polymorphism, as well as of the protective haplotypes TACAC and TACC and of the risk haplotype TTTC in SS patients prone to NHL development (high risk determined by the presence of adverse predictors), compared to low-risk individuals [133]. Additionally, a specific mutation (His159Tyr) of BAFF receptor (BAFF-R) is of interest, as it has been identified in more than two thirds of SS-associated MALT lymphoma. This mutation, leading to NF-kB pathway activation, was linked to earlier development of lymphoma or adverse immunological features (hypergammaglobulinemia and positive RF) [78, 134].


Finally, Fms-like tyrosine kinase 3 ligand (Flt-3 l) is a protein that acts as a cytokine and a growth factor, activating Flt-3 (or CD135) on the surface of hematopoietic progenitor cells, and therefore considered to be a mediator of B-cell survival. Higher levels of Flt-3l are strongly associated with history of lymphoma, detectable years before malignant transformation, and not affected by treatment [135].


The vicious circle of autoreactive B-cell chronic stimulation and immunocomplexes formation might finally lead to the favorable, monoclonal expansion of rheumatoid factor (RF)-reactive B cells and to the lymphomatous transformation, under defective immunosurveillance [4]. As a matter of fact, IFNα mRNA levels in MSGBs seem to strongly correlate with the expression of pro-apoptotic molecules (tumor suppressor gene p53 and auto-antigen Ro52, with the latter negatively regulating the anti-apoptotic B-cell lymphoma 2 (Bcl-2) gene) [132]. Moreover, decreased prevalence of a specific TREX1 variant (rs11797 AA genotype) in SS-related non-MALT cases was observed. This variant was shown to associate with higher mRNA IFNα levels in SS salivary gland tissues [136].


Further oncogenic mechanisms, likely to contribute to malignant turn in SS, are the over-expression of Bcl-2 due to a translocation involving chromosomes 14 and 18, leading to inhibition of apoptosis and increased B-cell survival. Apart from IFNα effect on p53 levels, specific mutations of this tumor suppressor gene were described 20 years ago in MSGBs from SS-associated NHL cases [4, 132, 137].


Epigenetic changes, involving methylating enzymes and transcription of noncoding micro-RNAs, are also implicated in lymphomagenesis [138]. MiR200b miRNAs, which regulate the expression of oncogenes and tumor suppressor genes, have been found to be downregulated in MSGBs with advanced lymphocytic infiltration and MALT lymphoma [139]. Especially miR200b-5p strongly discriminates SS patients who already have or will develop NHL from the rest of them or from sicca controls [140]. As for methylating enzymes, DNA methyltransferase (DNMT)3B and methyl-CpG-binding protein 2 (MeCP2) have been found decreased in SS-lymphoma patients [141], while methylene-tetrahydrofolate reductase (MTHFR) gene variants, leading to defective methylation and impaired stability of DNA, have lately been suggested as susceptibility factors for non-MALT lymphoma [142].


It becomes clear that the multifactorial process of lymphomagenesis is rather complicated, and the finely tuned balance between opposing forces can become deranged and lead to adverse outcomes. An example of that is the IFNγ/IFNα mRNA ratio in MSGBs, which has emerged as a histopathological biomarker for the prediction of in situ lymphoma development [132].


SS-related hematological malignancies are correlated with an eightfold higher mortality risk compared to general population [69], and one in five deaths of SS is attributable to lymphoma [68]. Follow-up every 6 months is recommended for high-risk patients. Overall, NHL 5-year survival is estimated at approximately 92%, but higher disease activity is linked to higher possibility of relapse and death [143145]. Wait and watch strategy is suitable for MALT lymphomas localized in the salivary glands, while rituximab and chemotherapy are employed in case of disseminated or aggressive disease [106, 146, 147, 149].


Multiple-Choice Questions





  1. 1.

    Which of the following clinical features would set Sjögren’s syndrome (SS) on top of your differential diagnosis list?
Oct 24, 2020 | Posted by in RHEUMATOLOGY | Comments Off on Syndrome
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