Background A close association between hepatitis C virus (HCV) chronic infection and Sjögren syndrome (SS) was reported 10 years ago. Recently, human La protein has been implicated in facilitating the internal initiation of translation as well as replication of HCV RNA. It could be hypothesized that patients carrying anti-La antibodies could be protected against chronic HCV infection.
Objectives To analyse the possible association between anti-La antibodies and chronic HCV infection in a large series of patients with SS.
Methods The study cohort included patients who were consecutively tested for IgG antibodies against HCV. Inclusion criteria were the fulfillment of at least 4 of the classification criteria for SS proposed by the European Community Study Group and repeated positive HCV serology; we retrospectively evaluated confirmation of HCV infection using recombinant immunoblot assay and detection of serum HCV-RNA by polymerase chain reaction, and HCV genotyping.
Results Six hundred sixty three patients with SS were included (602 female and 61 male; mean age, 58 yr). One hundred and four patients (16%) showed IgG antibodies against HCV; 9 patients showed a positive serology result with negative HCV viremia, suggesting a past/cured HCV infection. In comparison with the remaining 64 patients with chronic HCV infection (IgGHCV+, RNAHCV+), the 9 patients IgGHCV+/RNAHCV- were more frequently female (100% vs 80%, p>0.05) and had a lower frequency of hypocomplementemia (22% vs 70%, p=0.008) and positive serum cryoglobulins/monoclonal band (33% vs 71%, p=0.032); interestingly, none of these 9 patients had anti-La antibodies (0% vs 19%, p>0.05). HCV genotyping was available in 42 patients (1b in 30 patients, 1a in 7 and non-1 in the remaining 4; one patient was non typable). In the whole cohort of patients with SS, patients with associated chronic HCV infection showed a differentiated immunological expression, with a lower frequency of autoantibodies including antinuclear antibodies (71% vs 85%, p=0.001), anti-Ro (15% vs 38%, p<0.001) and anti-La (17% vs 29%, p=0.008), and a higher frequency of cryoglobulinemic-related markers including serum cryoglobulins (54% vs 6%, p<0.001), positive RF (56% vs 42%, p=0.011), low C3 values (32% vs 10%, p<0.001), low C4 values (47% vs 8%, p<0.001) and serum monoclonal band (42% vs 19%, p<0.001) in comparison with no-HCV patients with SS.
Conclusions The main differential aspect between primary and HCV-related SS is the immunological pattern, with a predominance of cryoglobulinemic-related markers (mixed cryoglobulins, RF, hypocomplementemia, monoclonal band) over SS-related specific markers (anti-Ro/SS-A and anti-La/SS-B autoantibodies) in HCV-related SS. Cryoglobulinemia is the key immunological marker of SS associated with HCV, while anti-La antibodies were less frequently detected in HCV patients and do not seem that could influence in protecting against chronic HCV infection in SS patients.
Disclosure of Interest : None declared