TREX1 acts in the initial prevention of an autoimmune response, but it may contribute to the permissiveness of retrovirus infections. This study investigated the association between the levels of TREX1 gene expression with the polymorphisms TREX1 rs3135941 (T/C) and TREX1 rs3135945 (G/A), and the presence of antinuclear antibodies (ANA) in antiretroviral therapy (ART)-naïve individuals and after 1 year of treatment. Blood samples from 119 individuals with HIV-1 were subjected to genotyping of polymorphisms and quantification of TREX1 gene expression and HIV-1 viral load by qPCR. The concentration of IFN-α and the number of CD4⁺/CD8⁺ T lymphocytes were determined by ELISA and flow cytometry, respectively; ANA was investigated by immunofluorescence. A control group of 167 seronegative individuals was used for the comparison of genotypic frequencies. The frequency of the polymorphisms were not associated with HIV infection or with variations in the expression of TREX1 and IFN-α (p > 0.05). ART-naïve individuals exhibited higher TREX1 expression and lower IFN-α expression. After 1 year of ART, TREX1 levels were reduced, while IFN-α and CD4⁺ T lymphocytes were elevated (p < 0.05). Some individuals on ART presented ANA. These results suggest that ART-mediated restoration of immune competence is associated with a reduction in TREX1 expression, which may induce the development of ANA, regardless of the polymorphism investigated.

The apoptotic molecule Fas and its ligand FasL are involved in the process of T-lymphocyte death, which may lead to lymphopenia, a characteristic of severe coronavirus disease 2019 (COVID-19). In this study, we investigated the influence of polymorphisms in the FAS and FASL genes, FAS and FASL gene expression, and plasma cytokine levels on COVID-19 severity and long COVID occurrence. A total of 116 individuals with severe COVID-19 and 254 with the non-severe form of the disease were evaluated. In the post-COVID-19 period, samples from 196 individuals with long COVID and 67 from people who did not have long COVID were included. Genotyping and quantification of gene expression were performed via real-time PCR, and cytokine measurement was performed via flow cytometry. The AA genotype for FAS rs1800682 (A/G) and the TT genotype for FASL rs763110 (C/T) were associated with increased FAS and FASL gene expression, respectively (p < 0.005). Higher plasma IFN-γ levels were associated with higher FAS and FASL gene expression (p < 0.05). Among individuals with non-severe COVID-19, carriers of the AA genotype for FAS rs1800682 (A/G) had higher levels of FAS expression, more symptoms, and higher IFN-γ levels (p < 0.05). No association of the evaluated markers with long COVID were observed. The AA genotype of FAS rs1800682 (A/G) and the TT genotype of FASL rs763110 (C/T) influence the levels of FAS and FASL gene expression. Higher gene expression of FAS and FASL may lead to greater inflammation in COVID-19 patients, with higher levels of IFN-γ and T lymphocyte death.