Background and Aims

Develop a routine whole blood interferon gamma release assay (IGRA) remains mandatory to study SARS-Cov2-specific memory T cell responses in immunocompromised individuals such as those with autoimmune diseases, the aim of the study.

Methods

Preliminary experiments were initiated to evaluate different Spike T cell response in twenty volunteers vaccinated with BNT162b2 using different platforms (ELISpot, IGRA, recombinant proteins or peptides). Next, 103 non-vaccinated healthy individuals and 70 samples from individuals having received COVID19 vaccine including 20 non-Sars-Cov2 infected patients with autoimmune/immunodeficiency diseases (e.g. SLE, SEP, GCA…) were tested for T cell and humoral responses.

Results

First, full length recombinant proteins rather than peptides were selected to develop a whole blood IGRA assay for routine. Next and following COVID19 vaccination, anti-Spike antibodies response (100% in healthy vs 71.4% in patients) and IGRA-Spike T cell response (98% in healthy vs 61.9% in patients) took place as compared to non vaccinated individuals that presented a SARS-Cov2 infection rate around 10% (IGRA-nucleocapsid and/or IgG anti-nucleocapsid). Among the autoimmune/immunodeficiency disease group, steroids rather than biologics (e.g. rituximab, tocilizumab…) affect the cellular response before and after the third/fourth vaccine boost. Within the healthy group, COVID19 vaccine humoral response decreases first (>100 days) followed by the cellular response (>200 days), which can be reversed following vaccine boost.

Conclusions

This ongoing study confirms the utility of the IGRA-Spike/-nucleocapsid assay coupled with serology in COVID19 vaccinated individuals and in particular in those immunocompromised such as patients with autoimmune diseases treated with steroids.

Background and Aims

Rheumatoid arthritis (RA) is a systemic autoimmune disease, caused by the combination of genetic factors, environmental factors, and a role for gut microbiome is also suspected at preclinical stage. However, how these factors interact remains unclear, which is the aim of this study.

Methods

54 patients with RA, 48 preclinical individuals including 8 who have developed to RA and 31 controls (HC) were selected from the Tatarstan’s cohort, and tested for gut microbiota (16S rRNA). The analysis of RA-associated factor included HLA locus variability (HLA-A/B/C/DQ and DRB1), cytokine polymorphism, haplomitotype determination, and a large panel of environmental factors.

Results

No difference was observed when considering alpha diversity, beta diversity, and microbiome composition between samples from controls, preclinical individuals and RA patients. In contrast HLA-DRB1 (SE, beta diversity) and the education level (alpha & beta diversity) influence microbiome. At genus level, Prevotella species including Prevotella copri, were more abundant in controls and at preclinical stage within the low education subgroup. Next, an immunization against Prevotella sp is suspected as a reduction was observed among RA and preclinical individuals evolving to RA among the low education/HLA-DRB1-SE subgroup.

Conclusions

Prevotella sp is overexpanded in stool samples from low educated individuals and among then HLA-DRB1-SE represents a risk factor for RA.

Funding: “Russian Foundation for Basic Research” (№ 20-515-05006)