Sjögren's syndrome and systemic lupus erythematosus: links and risks

Abstract

Systemic lupus erythematosus (SLE) and Sjögren's syndrome (SS) may coexist, and they are chronic complex disorders, with an autoimmune background, multifactorial etiology, multiple circulating autoantibodies, and variable prognosis. The prominent feature of SS is the impairment of the lacrimal and salivary glands leading to sicca symptoms. This disease may be classified as primary Sjögren's syndrome (pSS), or secondary Sjögren's syndrome (sSS) since it is often associated to other autoimmune disorders, principally SLE, rheumatoid arthritis, and systemic sclerosis. Systematic reviews and meta-analyses show an sSS prevalence in SLE patients of about 14%-17.8%. Herein, we updated important aspects of the clinical association between SLE and sSS through a narrative review of the PubMed database in the last 5 years (from July 2013 to October 2018) with the terms "Sjogren syndrome and systemic lupus erythematosus". The following aspects are addressed: the classification criteria for sSS; differences and similarities between SLE and pSS regarding demographic, clinical, and serological characteristics (including new autoantibodies), as well as comorbidities; the etiopathogenic links between SLE and pSS (including genetic and environmental factors, B-cell activation, and autoantibodies); the predictive factors for sSS onset in SLE patients; the ocular and oral involvements due to sSS in SLE; and the main distinctive demographic, clinical, and serological features of SLE with and without associated SS.

Keywords: anti-Ro; anti-SSA; autoantibodies; pathogenesis; polyautoimmunity; primary Sjögren’s syndrome; secondary Sjögren’s syndrome; systemic lupus erythematosus.

Figure 1

Scheme illustrating the classification criteria (according to The American-European Consensus Group14) for secondary Sjögren’s syndrome. Notes: Ocular objective tests: Schirmer’s I test (A) and ocular color score, eg, lissamine green (B). Oral objective tests: unstimulated salivary flow (C), salivary gland scintigraphy, and sialography-imaging test of the parotid glands. Histological image of the minor salivary glands (H&E; image courtesy: Professor Daniela Assis do Vale, Oral and Maxillofacial Pathology Department, School of Dentistry, University of Sao Paulo, Sao Paulo, Brazil) (D) showing foci of lymphocytes (arrows).

Figure 2

Antinuclear antibodies test (indirect immunofluorescence on HEp-2 cells) showing the nuclear fine speckled pattern (A). Illustrative image of anti-Ro (SSA) and anti-La (SSB) antibodies detected by counterimmunoelectrophoresis (B). 1, 2, 6, 7: negative serum samples; 3, 4: serum samples positive for anti-Ro (SSA) and anti-La (SSB); 5: serum sample positive for other reactivity (anti-U1RNP).

Figure 3

Main etiopathogenic links between SLE and pSS. Abbreviations: pDC, plasmacytoid dendritic cell; Th, T helper lymphocyte; SLE, systemic lupus erythematosus; pSS, primary Sjögren’s syndrome.