Anti-ribonucleoproteins autoantibodies in patients with systemic autoimmune diseases. Relation with cutaneous photosensitivity

Abstract

A common feature between patients with a certain group of systemic autoimmune pathologies (SAPs) with rheumatic component, such as lupus erythematosus (LE) in all its forms, is the presence of cutaneous photosensitivity (CP) as well as the existence of autoantibodies (Aabs). These Aabs have also high incidence in other SAPs that do not present CP, like primary Sjögren's syndrome and rheumatoid arthritis. Cutaneous photosensitivity is a condition that consists of an exacerbated skin reaction to solar radiations; its incidence can reach 90% in systemic LE. The mechanisms involved in the development of CP have been extensively studied focusing on different approaches; however, the exact mechanism has not been fully elucidated yet. There are many theories that relate specifically the presence of circulating anti-Ro/SS-A Aabs with the CP phenomenon, though there are several studies which are in disagreement. In this study, we evaluated the Aabs profile (anti-Ro/SS-A 52 kDa, anti-Ro/SS-A 60 kDa, anti-La/SS-B, anti-Sm and ANAs) as well as their titer or reactivity, in a local cohort of 169 patients with SAPs. We related those Aabs profiles and titers with the presence or absence of CP, and we found that there was no significant association between the presence of anti-Ro/SS-A Aabs and the occurrence of CP. On the other hand, a statistically significant positive association was found between CP and high reactivity anti-Sm Aabs, though this fact could be biased by the incidence of both events in SLE patients. To sum up, in the particular population studied, there is no direct relationship between anti-Ro/SS-A Aabs and CP, which is in agreement with some authors and in disagreement with many others, contributing to the endless discussion of this issue.

Anti-Ro antibody and clinical manifestations: lessons from systemic lupus erythematosus in the elderly

“…In contrast, skin vasculitis, photosensitivity and Raynaud phenomenon occured rarely in the elderly patients [4]. The review may prove that anti-Ro antibody is associated to prevalence of anti-La antibody but not photosensitivity, cutaneous vasculitis and Raynaud phenomenon, which is in agreement with most findings from the reports discussed above [1][2][3]. It should be noted that further studies are required to clarify precise molecular mechanism.…”

“…However, available evidence suggests that there still exist a large number of inconsistencies. Recently, Paz et al reported that there was no direct relationship between anti-Ro antibody and cutaneous photosensitivity in SLE patients [1]. Another study also found that anti-Ro antibody was not associated to photosensitivity.…”

Two Approaches to the Study of a Controversial Relationship: Cutaneous Photosensitivity and Anti-Ro/SS-A Autoantibodies

“…A cohort of 169 individuals were examined at the Rheumatology Service of the Hospital de Clínicas José de San Martín, as part of a previous larger study [24], then 10 of those patients were selected for this study, according to their clinical characteristics and laboratory findings. Diagnoses of SLE, SS, Rheumatoid Arthritis (RA) and CP were made according to the criteria adopted in the abovementioned previous study.…”

“…Recombinant human Ro/SS-A 52 kDa and Ro/SS-A 60 kDa (Ro52 and Ro60 hereafter) were cloned and expressed in an E-coli system, where a N-terminal 6× Histidine-tag was added to the proteins and then they were purified using an immobilized metal ion adsorption chromatography, as described before [24]. Aabs against either Ro52 or Ro60 proteins were isolated from sera by affinity chromatography, using the corresponding recombinant protein coupled to CNBr-activated Sepharose 4B (GE Healthcare, Little Chalfont, Buckinghamshire, United Kingdom) according to the manufacturer's instructions.…”

“…Nevertheless, there are some facts which are in disagreement with the previous statement. To begin with, there are epidemiological data which indicate that there is not a significant direct association between anti-Ro/ SS-A Aabs and CP [22][23][24]; moreover there is the fact that 75% of pSS's patients do have anti-Ro/SS-A Aabs, many with high Aabs titers, but not CP [25,26]; furthermore there is the occurrence of CP in individuals that do not show any kind of disease, neither any circulating Aabs [27]. Anyhow, beyond all this controversy the actual mechanism which triggers CP has not been fully elucidated yet, though the relationship between CP and anti-Ro/SS-A Aabs has been studied focusing on different aspects.…”