Age-dependent effect of the IFIH1/MDA5 gene variants on the risk of critical COVID-19.

MDA5, encoded by the IFIH1gene, is a cytoplasmic sensor of viral RNAs that triggers interferon (IFN) antiviral responses. Common and rare IFIH1 variants have been associated with the risk of type 1 diabetes and other immune-mediated disorders, and with the outcome of viral diseases. Variants associated with reduced IFN expression would increase the risk for severe viral disease. The MDA5/IFN pathway would play a critical role in the response to SARS-CoV-2 infection mediating the extent and severity of COVID-19. Here, we genotyped a cohort of 477 patients with critical ICU COVID-19 (109 death) for three IFIH1 functional variants: rs1990760 (p.Ala946Thr), rs35337543 (splicing variant, intron 8 + 1G > C), and rs35744605 (p.Glu627Stop). The main finding of our study was a significant increased frequency of rs1990760 C-carriers in early-onset patients (< 65 years) (p = 0.01; OR = 1.64, 95%CI = 1.18-2.43). This variant was also increased in critical vs. no-ICU patients and in critical vs. asymptomatic controls. The rs35744605 C variant was associated with increased blood IL6 levels at ICU admission. The rare rs35337543 splicing variant showed a trend toward protection from early-onset critical COVID-19. In conclusion, IFIH1 variants associated with reduced gene expression and lower IFN response might contribute to develop critical COVID-19 with an age-dependent effect.

Influence of the HLA-Cw6 Allele and IFIH1/MDA5 Gene Variants on the Cardiometabolic Risk Profile of Patients with Psoriatic Disease.

BACKGROUND: Cardiovascular comorbidity is a common companion of psoriasis and psoriatic arthritis (PsA). Recently, a significant link has been found between the HLA-Cw6 allele and a better cardiometabolic profile in these patients. We aimed to check this finding in our setting. METHODS: A cross-sectional observational study (n: 572 psoriasis patients, 30% with PsA) was conducted. Different study variables were collected in detail, as well as classic cardiometabolic risk factors. The distribution of the HLA-Cw6 allele and the IFIH1/MDA5 gene variants previously linked to disease risk were determined in the study cohort and stratified according to the cardiometabolic comorbidity. Linear and logistic regression models were constructed to analyze these associations. RESULTS: The study cohort included 309 men and 263 women, with a mean age of 46.7 years (SD 14.5) and a mean disease duration of 19.4 years (SD 14.8). We confirmed the known association between HLA-Cw6 and type I psoriasis (familial, severe, and early onset). Psoriasis severity (OR: 2.14), female sex (OR: 1.63), and the IFIH1/MDA5 rs1990760 TT genotype (OR: 1.62) were significantly related to PsA, while HLA-Cw6 was protective (OR: 0.65). HLA-Cw6 carriers showed a lower waist perimeter, lower BMI, and lower risk of both hypertension (OR: 0.52, p < 0.001) and diabetes (OR: 0.36, p < 0.001), but these findings were no longer apparent upon adjusting the regression models. No IFIH1/MDA5 gene variant was associated with any cardiometabolic risk factor. CONCLUSIONS: The influence of HLA-Cw6 on the cardiometabolic risk profile of psoriatic patients seems to be explained by other factors (age, sex, duration of the disease or arthritis) and not by this biomarker itself.

Integrative RNA profiling of TBEV-infected neurons and astrocytes reveals potential pathogenic effectors.

Tick-borne encephalitis virus (TBEV), the most medically relevant tick-transmitted flavivirus in Eurasia, targets the host central nervous system and frequently causes severe encephalitis. The severity of TBEV-induced neuropathogenesis is highly cell-type specific and the exact mechanism responsible for such differences has not been fully described yet. Thus, we performed a comprehensive analysis of alterations in host poly-(A)/miRNA/lncRNA expression upon TBEV infection in vitro in human primary neurons (high cytopathic effect) and astrocytes (low cytopathic effect). Infection with severe but not mild TBEV strain resulted in a high neuronal death rate. In comparison, infection with either of TBEV strains in human astrocytes did not. Differential expression and splicing analyses with an in silico prediction of miRNA/mRNA/lncRNA/vd-sRNA networks found significant changes in inflammatory and immune response pathways, nervous system development and regulation of mitosis in TBEV Hypr-infected neurons. Candidate mechanisms responsible for the aforementioned phenomena include specific regulation of host mRNA levels via differentially expressed miRNAs/lncRNAs or vd-sRNAs mimicking endogenous miRNAs and virus-driven modulation of host pre-mRNA splicing. We suggest that these factors are responsible for the observed differences in the virulence manifestation of both TBEV strains in different cell lines. This work brings the first complex overview of alterations in the transcriptome of human astrocytes and neurons during the infection by two TBEV strains of different virulence. The resulting data could serve as a starting point for further studies dealing with the mechanism of TBEV-host interactions and the related processes of TBEV pathogenesis.

Interstitial Lung Disease and Psoriasis in a Child With Aicardi-Goutières Syndrome.

Aicardi-Goutières syndrome (AGS) is characterized by progressive neurologic decline, cerebral calcification, and variable manifestations of autoimmunity. Seven subtypes of AGS have been defined and aberrant activation of the type I interferon system is a common theme among these conditions. We describe a 13-year-old boy who presented with an unusual constellation of psoriasis, interstitial lung disease (ILD), and pulmonary hypertension in addition to cerebral calcifications and glomerulonephritis. He was found to have late-onset AGS due to a gain-of-function mutation in IFIH1 and over-activation of the type I interferon pathway was confirmed by RNA sequencing. The majority of his clinical manifestations, including ILD, psoriasis and renal disease improved markedly after treatment with the combination of corticosteroids, cyclophosphamide, and the Janus-kinase inhibitor tofacitinib. This case extends the clinical spectrum of AGS and suggests the need for lung disease screening in patients with AGS.