The occurrence of sacroiliitis in HLA-B*35-positive patients with undifferentiated spondyloarthritis. A cross sectional MRI study.

OBJECTIVE: To investigate possible association between sacroiliitis and HLA-B*35 positivity. METHOD: After excluding patients with axial spondyloarthritis and HLA-B*27 positivity, psoriasis inflammatory bowel disease, preceding infections, or juvenile type of spondyloarthritis, 110 patients were recruited with a diagnosis of undifferentiated axial spondyloarthritis. All of them had inflammatory back pain of short duration (3 months to 2 years) and 72 were HLA-B*35 positive. In order to determine if there is a possible association of sacroiliitis and HLA-B*35 positivity, all patients underwent MRI of sacroiliac joints. RESULTS: A statistically significant association between the detection of bone marrow edema at sacroiliac joints on MRI and HLA-B*35 positivity (χ2 = 6.25; p = 0.022) was found. A logistic regression analysis revealed that the presence of HLA-B*35 allele was associated with a 6 times greater chance of identifying bone marrow edema at sacroiliac joints on MRI (OR 6, 95% CI 1.3-27, p = 0.021). HLA-B*35 positivity was also associated with a 4.7 times greater chance of finding elevated CRP (OR 4.7, 95% CI 1-11.9, p = 0.047) and a 5 times greater chance of finding peripheral joint synovitis (OR 5, 95% CI 1.75-14.3, p = 0.003). HLA-B*35-positive patients had high disease activity (mean ± SD of Bath Ankylosing Spondylitis Disease Activity Index 6.1 ± 1.72 and Ankylosing Spondylitis Disease Activity Score C-reactive protein Index 3 ± 0.64) with a high degree of functional limitations (mean ± SD of Bath Ankylosing Spondylitis Functional Index 5.3 ± 2.16). CONCLUSION: The data clearly show the association between bone marrow edema on MRI at sacroiliac joints and HLA-B*35 allele in patients with undifferentiated spondyloarthritis. Further work is needed to understand how much this result may influence follow-up of these patients. Key Points • HLA-B*35 allele was associated with a 6 times greater chance of identifying bone marrow edema at sacroiliac joints on MRI in un-axSpa patients. • HLA-B*35 allele was also associated with a 4.7 times greater chance of finding elevated CRP and a 5 times greater chance of finding peripheral joint synovitis in un-axSpa patients. • HLA-B*35 allele could be a potential risk factor for developing sacroiliitis and axSpA.

Anisakis Sensitization in the Croatian fish processing workers: Behavioral instead of occupational risk factors?

We undertook the first study systematically evaluating the risk of Anisakis-sensitization in Croatian fish-processing workers and potential genetic susceptibility to anisakiasis. Anti-Anisakis IgE seroprevalence and risk factors for 600 employees of Croatian fish processing facilities and 466 blood donor controls, were assessed by indirect ELISA targeted with: recombinant Ani s 1 and Ani s 7 allergens, an Anisakis crude extract, the commercial ImmunoCAP kit, and questionnaires. Genetic susceptibility to anisakiasis was evaluated by genotypisation of human leukocytes alleles (HLA). Anti-Anisakis seropositive and a fraction of negative subjects were also assessed by ELISA and Western Blot (WB) for IgG seroprevalence to Trichinella spp. Overall, the observed anti-Anisakis seroprevalence inferred by indirect ELISA was significantly higher in fish processing workers (1.8%, 95% CI 0.9-3.3%) compared to the controls (0%, 0-0.8%). Seven out of 11 Ani s 1 and Ani s 7-positives and none of selected 65 negative sera, tested positive on whole-Anisakis extract (ImmunoCAP), whereas Anisakis crude extract ELISA detected 3.9% (2.4-6.0%) seropositives in fish processing workers, three (14%) of which showed IgE reactivity to milk proteins. The highest risk associated with Anisakis-sensitization among workers was fishing in the free time, rather than any of attributes related to the occupational exposure. Although no association was observed between anti-Anisakis seropositivity and wearing gloves or protective goggles, the majority of workers (92%) wore protective gloves, minimizing the risk for Anisakis sensitization via skin contact. Six HLA alleles within DRB1 gene were significantly associated with seropositivity under dominant, allelic or recessive models. All sera confirmed negative for anti-Trichinella spp. IgG. The study exhaustively covered almost all marine fish processing workers in Croatia, reflecting real-time Anisakis sensitization status within the industry, already under the influence of wide array of allergens.