Lessons from diseases mimicking Sjögren's syndrome

[Sjögren syndrome]

In 1933, the Swedish ophthalmologist Hendrik Sjögren was the first to suggest that behind the dryness that several of his patients presented, there could be a systemic disease related to an abnormal immune response. Since then, the term Sjögren's syndrome (SjS) has been used and it has been considered a minor and infrequent disorder compared to other systemic autoimmune diseases (SAD) and, consequently, with little progress both in clinical and therapeutic research. The emergence of new technologies at the end of the 20th century rapidly promoted the development of international projects of great impact and diffusion, which have completely changed this scenario, and in the last 20 years significant progress has been made in understanding the main epidemiological determinants and pathogenic mechanisms to increase the diagnostic accuracy and to design specific and individualized therapeutic strategies. Currently, SjS should be considered one of the most frequent SADs with an undoubtedly systemic phenotype beyond dryness, in which the identification of prognostic factors can allow personalized follow-up and, therefore, early therapeutic interventions that avoid severe, irreversible outcomes.

Sjögren's Syndrome and Viral Infections

Sjögren's syndrome (SS) is a systemic autoimmune disease, characterized by lymphocytic infiltration of the secretory glands. This leads to dryness of the main mucosal surfaces such as the mouth, eyes, nose, larynx, pharynx, and vagina. Although there is little morbidity data at the initial diagnosis, SS may be a serious disease, with extra mortality caused by hematological cancer. The cause of SS is unknown, but factors postulated to play a role include genetic and environmental factors, hormonal abnormality, and viral infection. Under the influence of these factors, the immune system becomes abnormal and the tissue is damaged. In this study, we summarize recent developments in our understanding of the relationship between SS and viral infections, including Epstein-Barr virus (EBV), hepatitis C virus (HCV), human T cell lymphotropic virus type 1 (HTLV-1), cytomegalovirus (CMV), and human immunodeficiency virus (HIV).

Anti-DNase I Antibody: A New Serological Reactivity in Primary Sjögren Syndrome

BACKGROUND AND OBJECTIVE

Primary Sjögren syndrome (pSS) is a systemic autoimmune rheumatic disease that particularly affects exocrine glands. Dry eye is one of the most important features of this syndrome, and a recent study reported reduced deoxyribonuclease I (DNase I) activity in the tear of patients with dry eye. We therefore postulated that patients with pSS might have antibodies targeting DNAse I.

METHODS

We have evaluated in a cross-sectional study 85 patients with pSS (2002 American-European Consensus Group Criteria), 50 rheumatoid arthritis (RA) patients (1987 American College of Rheumatology Criteria) without sicca symptoms, and 88 healthy volunteers. IgG anti-DNase I was detected by enzyme-linked immunosorbent assay using as antigen bovine pancreas enzyme and confirmed by immunoblotting.

RESULTS

Age and sex were alike in the 3 groups (p > 0.05). Anti-DNase I was detected in 43.5% of the pSS patients. In contrast, this reactivity was absent in all RA patients (p = 0.0001). Additional comparison of pSS patients with (n = 37) or without (n = 48) anti-DNase I showed that the former group had higher IgG serum levels (2293.2 ± 666.2 vs 1483.9 ± 384.6 mg/dL, p = 0.0001) and greater rate of non-drug-induced leukopenia (43% vs 19%, p = 0.02). A multivariate logistic regression analysis identified that only IgG levels were independently associated with anti-DNase I.

CONCLUSIONS

We describe a high frequency of anti-DNase I antibodies in pSS patients associated with higher serum IgG levels. The lack of this reactivity in RA patients without sicca symptoms suggests that this antibody may be helpful in the differential diagnosis of these diseases.

Characterizing hand and wrist ultrasound pattern in primary Sjögren's syndrome: a case-control study

INTRODUCTION/OBJECTIVES

To evaluate the clinical relevance of high-resolution hand and wrist ultrasound (US) findings and their possible associations with anti-citrullinated peptide antibodies in primary Sjögren's syndrome (pSS).

METHODS

Ninety-seven consecutive pSS patients (American-European Consensus Group, 2002) without meeting the American College of Rheumatology (ACR) criteria (1987) for rheumatoid arthritis (RA); 20 RA patients (ACR/European League Against Rheumatism (EULAR) criteria, 2010); and 80 healthy individuals with comparable age, gender, and ethnicity were enrolled in a case-control study. Disease activity was assessed by EULAR Sjögren's Syndrome Disease Activity Index (ESSDAI). US was performed by one expert blinded to anti-CCP, anti-MCV, and IgM rheumatoid factor tested by ELISA.

RESULTS

Frequencies of grade 3 synovitis (9.3 vs. 0%, p = 0.004), tenosynovitis (36.1 vs. 3.8%, p < 0.001), and erosions (27.8 vs. 7.5%, p = 0.001) on US were higher in pSS patients than in healthy controls. ESSDAI presented a moderate correlation with the synovitis number (p = 0.001) and tenosynovitis (p < 0.001). Most pSS patients with erosions on US (81.5%) had negative anti-CCP. Nevertheless, anti-CCP ≥ 3× cut-off value was associated with the presence of erosions in pSS (p = 0.026). Erosions in pSS were mainly small size contrasting with moderate/large size in RA (p < 0.001), and positive power Doppler synovitis predominated in RA (p < 0.001).

CONCLUSIONS

US identified significant frequencies of grade 3 synovitis, tenosynovitis, and erosions in pSS. Synovitis and tenosynovitis numbers were correlated with ESSDAI. Association between erosions on US and anti-CCP (high titers) in pSS possibly identifies a subgroup with severe arthritis. These findings suggest that US is a useful method for assessing joint involvement in pSS.Key Points• US identified significant frequencies of grade 3 synovitis, tenosynovitis, and erosions in pSS patients in comparison with age- and race-healthy individuals.• Numbers of synovitis and tenosynovitis on US were correlated with ESSDAI values.• Most pSS patients with erosions on US were negative for anti-CCP, but anti-CCP ≥ 3× cut-off value was associated with the presence of erosions in this disease.• Erosions in pSS were mainly small size contrasting with moderate/large size in RA, and positive power Doppler synovitis predominated in RA.

The oral mucosa: A barrier site participating in tissue-specific and systemic immunity

In the oral cavity, the immune system is constantly exposed to unique tissue-specific signals, including a rich community of commensal microbes and their metabolites, continuous tissue damage from mastication, and antigens from food and airborne particles. How this unique combination of signals participates in the training of specialized immunity at this site is not well understood, yet imbalance of local responses is linked to tissue-specific disease susceptibilities with the prototypic disease being periodontitis. However, the oral mucosa is also well recognized as a site where systemic inflammatory and autoimmune diseases often manifest, indicating that systemic immune deregulation is reflected in the function of the oral immune system. This commentary will discuss both aspects of compartmentalized and systemic immunity at the oral mucosa.

Oxidative stress in autoimmune rheumatic diseases

The management of patients with autoimmune rheumatic diseases such as rheumatoid arthritis (RA) remains a significant challenge. Often the rheumatologist is restricted to treating and relieving the symptoms and consequences and not the underlying cause of the disease. Oxidative stress occurs in many autoimmune diseases, along with the excess production of reactive oxygen species (ROS) and reactive nitrogen species (RNS). The sources of such reactive species include NADPH oxidases (NOXs), the mitochondrial electron transport chain, nitric oxide synthases, nitrite reductases, and the hydrogen sulfide producing enzymes cystathionine-β synthase and cystathionine-γ lyase. Superoxide undergoes a dismutation reaction to generate hydrogen peroxide which, in the presence of transition metal ions (e.g. ferrous ions), forms the hydroxyl radical. The enzyme myeloperoxidase, present in inflammatory cells, produces hypochlorous acid, and in healthy individuals ROS and RNS production by phagocytic cells is important in microbial killing. Both low molecular weight antioxidant molecules and antioxidant enzymes, such as superoxide dismutase, catalase, glutathione peroxidase, and peroxiredoxin remove ROS. However, when ROS production exceeds the antioxidant protection, oxidative stress occurs. Oxidative post-translational modifications of proteins then occur. Sometimes protein modifications may give rise to neoepitopes that are recognized by the immune system as 'non-self' and result in the formation of autoantibodies. The detection of autoantibodies against specific antigens, might improve both early diagnosis and monitoring of disease activity. Promising diagnostic autoantibodies include anti-carbamylated proteins and anti-oxidized type II collagen antibodies. Some of the most promising future strategies for redox-based therapeutic compounds are the activation of endogenous cellular antioxidant systems (e.g. Nrf2-dependent pathways), inhibition of disease-relevant sources of ROS/RNS (e.g. isoform-specific NOX inhibitors), or perhaps specifically scavenging disease-related ROS/RNS via site-specific antioxidants.

Expression of IL-17, IL-23 and their receptors in minor salivary glands of patients with primary Sjögren's syndrome

The main purpose of this study was to determine the expression of interleukins-17/-23 (ILs-17/-23) and receptors of interleukins-17/-23 (IL-17R, IL-23R) in minor salivary glands (MSGs) of patients with primary Sjögren's syndrome (pSS). Expression of IL-17, IL-23 and receptors of IL-17/-23 was analyzed in MSGs from 25 patients with pSS, 25 patients with probable preclinical pSS, and 25 patients with nonautoimmune sicca syndrome by immunohistochemistry. Comparison of the expression of IL-17, IL-23 and receptors of IL-17, IL-23 in MSG of patients with pSS with probable preclinical pSS, and with nonautoimmune sicca syndrome showed significant differences between three groups. However, the expression of IL-17, IL-23 and receptors of IL-17/-23 in MSG was comparable in pSS and probable preclinical pSS patients. We did not find correlation between the expression of IL-17 and IL-23 and of IL-17R and IL-23R in patients with pSS. These results demonstrate an involvement of IL-17/-23 system in the early pSS pathogenesis.

Sjögren syndrome or sjögren disease? The histological and immunological bias caused by the 2002 criteria

The current 2002 classification criteria do not cover the broad clinical and immunological heterogeneity of primary Sjögren syndrome (SS), since five of the six criteria focus exclusively on glandular involvement and the remaining criterion is the mandatory presence of anti-Ro/La antibodies. The aim of this study was to analyze the clinical features of patients with a well-established diagnosis of primary SS who do not fulfill the 2002 classification criteria. Five hundred seven patients diagnosed with primary SS (1993 criteria) were consecutively included and followed up. Two hundred twenty-one (44%) patients did not fulfill the 2002 criteria. These patients were older at diagnosis (p < 0.001) and had a lower frequency of parotid enlargement (p = 0.002), fever (p = 0.041), arthritis (p = 0.041), vasculitis (p = 0.050), peripheral neuropathy (p = 0.002), cranial nerve involvement (p = 0.015), raised erythrocyte sedimentation rate ( ESR) levels (p < 0.001), anemia (p < 0.001), leukopenia (p = 0.037), hypergammaglobulinemia (p < 0.001), positive rheumatoid factor ( RF; p = 0.002), and cryoglobulinemia (p = 0.049) in comparison with those fulfilling 2002 criteria. However, there were no significant differences in the prevalence of sicca features, diagnostic tests, overall systemic involvement, antinuclear antibodies , complement levels, development of B-cell lymphoma, or survival. Patients with anti-Ro antibodies had the highest frequencies of systemic features, hematological abnormalities, and altered immunological markers. In conclusion, patients fulfilling the 2002 criteria, who have either a specific histological diagnosis (lymphocytic infiltration) or highly specific autoantibodies (Ro/La), might well be considered to have Sjögren "disease." In contrast, etiopathogenic mechanisms other than lymphocytic-mediated epithelial damage could be involved in patients with negative Ro and negative biopsy, in whom the term Sjögren "syndrome" seems more adequate.