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SARS-CoV-2 infection is a world-wide public health problem. Several aspects of its pathogenesis and the related clinical consequences still need elucidation. In Italy, Sardinia has had very low numbers of infections. Taking advantage of the low genetic polymorphism in the Sardinian population, we analyzed clinical, genetic and immunogenetic factors, with particular attention to HLA class I and II molecules, to evaluate their influence on susceptibility to SARS-CoV-2 infection and the clinical outcome. We recruited 619 healthy Sardinian controls and 182 SARS-CoV-2 patients. Thirty-nine patients required hospital care and 143 were without symptoms, pauci-symptomatic or with mild disease. For all participants, we collected demographic and clinical data and analyzed the HLA allele and haplotype frequencies. Male sex and older age were more frequent in hospitalized patients, none of whom had been vaccinated during the previous seasonal flu vaccination campaignes. Compared to the group of asymptomatic or pauci-symptomatic patients, hospitalized patients also had a higher frequency of autoimmune diseases and glucose-6-phosphate-dehydrogenase (G6PDH) deficiency. None of these patients carried the beta-thalassemia trait, a relatively common finding in the Sardinian population. The extended haplotype HLA-A*02:05, B*58:01, C*07:01, DRB1*03:01 [OR 0.1 (95% CI 0-0.6), Pc = 0.015] was absent in all 182 patients, while the HLA-C*04:01 allele and the three-loci haplotype HLA-A*30:02, B*14:02, C*08:02 [OR 3.8 (95% CI 1.8-8.1), Pc = 0.025] were more frequently represented in patients than controls. In a comparison between in-patients and home care patients, the HLA-DRB1*08:01 allele was exclusively present in the hospitalized patients [OR > 2.5 (95% CI 2.7-220.6), Pc = 0.024]. The data emerging from our study suggest that the extended haplotype HLA-A*02:05, B*58:01, C*07:01, DRB1*03:01 has a protective effect against SARS-CoV-2 infection in the Sardinian population. Genetic factors that resulted to have a negative influence on the disease course were presence of the HLA-DRB1*08:01 allele and G6PDH deficiency, but not the beta-thalassemic trait. Absence of influenza vaccination could be a predisposing factor for more severe disease.

The diversity in the clinical course of COVID-19 has been related to differences in innate and adaptative immune response mechanisms. Natural killer (NK) lymphocytes are critical protagonists of human host defense against viral infections. It would seem that reduced circulating levels of these cells have an impact on COVID-19 progression and severity. Their activity is strongly regulated by killer-cell immuno-globulin-like receptors (KIRs) expressed on the NK cell surface. The present study's focus was to investigate the impact of KIRs and their HLA Class I ligands on SARS-CoV-2 infection. KIR gene frequencies, KIR haplotypes, KIR ligands and combinations of KIRs and their HLA Class I ligands were investigated in 396 Sardinian patients with SARS-CoV-2 infection. Comparisons were made between 2 groups of patients divided according to disease severity: 240 patients were symptomatic or paucisymptomatic (Group A), 156 hospitalized patients had severe disease (Group S). The immunogenetic characteristics of patients were also compared to a population group of 400 individuals from the same geographical areas. Substantial differences were obtained for KIR genes, KIR haplotypes and KIR-HLA ligand combinations when comparing patients of Group S to those of Group A. Patients in Group S had a statistically significant higher frequency of the KIR A/A haplotype compared to patients in Group A [34.6% vs 23.8%, OR = 1.7 (95% CI 1.1-2.6); P = 0.02, Pc = 0.04]. Moreover, the KIR2DS2/HLA C1 combination was poorly represented in the group of patients with severe symptoms compared to those of the asymptomatic-paucisymptomatic group [33.3% vs 50.0%, OR = 0.5 (95% CI 0.3-0.8), P = 0.001, Pc = 0.002]. Multivariate analysis confirmed that, regardless of the sex and age of the patients, the latter genetic variable correlated with a less severe disease course [OR.sub.M = 0.4 (95% CI 0.3-0.7), P.sub.M = 0.0005, P.sub.MC = 0.005]. The KIR2DS2/HLA C1 functional unit resulted to have a strong protective effect against the adverse outcomes of COVID-19. Combined to other well known factors such as advanced age, male sex and concomitant autoimmune diseases, this marker could prove to be highly informative of the disease course and thus enable the timely intervention needed to reduce the mortality associated with the severe forms of SARS-CoV-2 infection. However, larger studies in other populations as well as experimental functional studies will be needed to confirm our findings and further pursue the effect of KIR receptors on NK cell immune-mediated response to SARS-Cov-2 infection.

Idiopathic Pulmonary Fibrosis (IPF) is a progressive and fatal lung disease with limited treatment options. Nintedanib and pirfenidone are the only antifibrotic drugs approved by both the USA and European medicinal agencies, but their efficacy and tolerability remain concerns. This exploratory study investigates the association between genetic variation in the Major Histocompatibility Complex (MHC) region and adverse effects (AEs) of these therapies. HLA genotyping has been previously performed in a discovery cohort of 124 IPF Italian patients, with recorded drug‐related AEs. Logistic regression analysis using an additive model identified HLA‐C*06:02 as a significant risk factor, increasing the likelihood of AEs sixfold in nintedanib‐treated patients (p = 0.0043, OR = 6.54, 95% C.I. 1.80–23.75). Notably, gastrointestinal toxicity—the most common AE—was strongly associated with this allele (p = 0.0005, OR = 11.85, 95% C.I. 2.94–47.71). These findings suggest a potential immune‐mediated mechanism involving IL‐23‐driven inflammation and underscore the importance of pharmacogenetic tools in tailoring antifibrotic therapy. Implementing genetic screening could help minimize AEs and improve patient outcomes. Larger studies are warranted to validate these associations and guide personalized treatment strategies.

Kidney transplantation is a life-saving treatment for patients with end-stage renal disease. However, despite progress in surgical techniques and patient management, immunological rejection continues to have a negative impact on graft function and overall survival. Incompatibility between donors and recipients for human leukocyte antigens (HLA) of the major histocompatibility complex (MHC) generates a series of complex cellular and humoral immune response mechanisms that are largely responsible for rejection and loss of graft function. Within this context, a growing amount of evidence shows that alloreactive natural killer (NK) cells play a critical role in the immune response mechanisms elicited by the allograft. Killer immunoglobulin-like receptors (KIRs) are prominent mediators of NK cell alloreactivity. A cohort of 174 first cadaveric kidney allograft recipients and their donors were selected from a total cohort of 657 transplanted patients for retrospective immunogenetic analyses. Patients with HLA Class II mismatches were excluded. HLA Class I allele frequencies were compared among patients with chronic rejection, patients with stable graft function and a group of 2388 healthy controls. Activating and inhibitory KIR gene frequencies, KIR haplotypes, KIR-HLA ligand matches/mismatches and combinations of recipient KIRs and donor HLA Class I ligands were compared among patients with and without chronic rejection and a group of 221 healthy controls. Patients transplanted from donors homozygous for HLA-C1 antigens had a significantly higher risk for chronic rejection than patients transplanted from donors homozygous or heterozygous for HLA-C2 antigens or with epitopes belonging to the HLA-Bw4 ligand group. The Kaplan-Meier curves obtained by dividing the patients into 3 groups according to the presence or absence of one or both of the combinations of recipient KIRs and donor HLA ligands (rKIR2DL1/dHLA-C2 and rKIR3DL1/dHLA-Bw4) showed a significantly higher cumulative incidence of chronic rejection in the group of patients completely lacking these functional units. These patients showed a progressively stronger decline in modification of diet in renal disease-estimated glomerular filtration rate. KIR genotyping should be performed at the time of enrolment of patients on the waiting list for organ transplantation. In our study, a significantly higher risk of chronic rejection after kidney transplantation was observed when recipient (r) and donor (d) pairs completely lacked the two functional rKIR-dHLA ligand combinations rKIR2DL1/dHLA-C2 and rKIR3DL1/dHLA-Bw4. This immunogenetic profile corresponds to low levels of NK cell inhibition. Therefore, patients with this high risk profile could benefit from immunosuppressive therapy aimed at reducing NK-cell cytotoxicity.

BackgroundIdiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease characterized by aberrant wound healing, immune dysregulation, heterogeneous trajectories, and poor prognosis. Only two antifibrotic agents, nintedanib and pirfenidone, are currently approved to slow disease progression, yet inter-individual variability in treatment benefit remains largely unexplained. In IPF, impaired NK-cell activity within the altered lung microenvironment may hinder removal of stressed or senescent cells, promoting fibrosis. The MHC-class I chain-related gene A (MICA) encodes a stress-induced ligand of the NKG2D receptor on NK and CD8+ T cells, crucial for immune surveillance.MethodsWe analyzed clinical and genetic data from 129 Sardinian IPF patients genotyped for MICA and stratified by antifibrotic therapy (nintedanib, pirfenidone, no therapy, and switchers). Genotypes were assessed in relation to longitudinal lung function, overall survival (OS), and treatment-specific outcomes using multivariate Cox models adjusted for demographic and immunogenetic variables.ResultsMICA-129 genotype frequencies were comparable across treatment groups. In nintedanib-treated patients, the Val/Val genotype was associated with significantly reduced 48-month OS versus Met/Met and Met/Val (p = 0.005). No statistically significant association was observed among pirfenidone-treated patients. After adjustment, Val/Val remained an independent predictor of mortality in the nintedanib group (p = 0.01), irrespective of HLA background.ConclusionsThe MICA-129 Val/Val genotype may represent a candidate immunogenetic marker associated with poorer outcome in nintedanib-treated patients with IPF, underscoring the influence of immune-genetic context on antifibrotic response. Although subgroup sizes limit precision, the consistency and mechanistic plausibility of the association support integrating MICA genotyping into future randomized trials to refine personalized therapeutic strategies in IPF.

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive lung disease characterized by the disruption of the alveolar and interstitial architecture due to extracellular matrix deposition. Emerging evidence suggests that genetic susceptibility plays a crucial role in IPF development. This study explores the role of human leukocyte antigen (HLA) alleles and haplotypes in IPF susceptibility and progression within the genetically distinct Sardinian population. Genotypic data were analyzed for associations with disease onset and progression, focusing on allele and haplotype frequencies in patients exhibiting slow (S) or rapid (R) progression. While no significant differences in HLA allele frequencies were observed between IPF patients and controls, the HLA-DRB1*04:05 allele and the extended haplotype (HLA-A*30:02, B*18:01, C*05:01, DQA1*05:01, DQB1*02:01, DRB1*03:01) were associated with a slower disease progression and improved survival (log-rank = 0.032 and 0.01, respectively). At 36 months, carriers of these variants demonstrated significantly better pulmonary function, measured with single-breath carbon monoxide diffusing capacity (DLCO%p) (p = 0.005 and 0.02, respectively). Multivariate analysis confirmed these findings as being independent of confounding factors. These results highlight the impact of HLA alleles and haplotypes on IPF outcomes and underscore the potential of the Sardinian genetic landscape to illuminate immunological mechanisms, paving the way for predictive biomarkers and personalized therapies.

Hepatocellular carcinoma (HCC) is the sixth most common cancer globally and the third leading cause of cancer-related mortality, primarily driven by viral infections (HCV, HBV) and steatotic liver diseases (SLD). Despite advances in treatment, early detection and accurate prognosis remain challenging. The Human leukocyte antigen G (HLA-G) molecule is dysregulated in various conditions, including cancers and viral infections. This study aimed to investigate HLA-G’s role in viral-related and SLD-driven HCC. We analyzed a cohort of 116 HCC patients and 140 healthy controls to assess HLA-G genetic variants and soluble levels. Results showed significantly higher levels of soluble HLA-G in HCC patients compared to controls (Pc = 0.003). Moreover, overall survival (OS) was significantly lower in patients with the extended HLA-G*01:01:01/UTR-1 haplotype (Log-rank test, p = 0.002), a trend consistent in both HCV and/or HBV-related HCC (p = 0.025) and SLD-related HCC (p = 0.018). Elevated sHLA-G levels were associated with shorter OS across both subgroups (p = 0.034 (HBV/HCV) and p = 0.010 (SLD), respectively). The findings suggest that elevated levels of soluble HLA-G and specific genetic variants are associated with poor prognosis in HCC patients, highlighting the potential of HLA-G as a prognostic biomarker in both viral-related and steatotic liver disease-related HCC.

Antibody-mediated rejection is a significant cause of kidney transplant failure. Recent studies have shown that the MHC class I gene influences the transplantation outcome. However, the role of the primary receptor, NKG2D, has yet to be explored. We aimed to investigate the correlation between recipient/donor allele matching and genotype with the risk of antibody-mediated rejection and their potential clinical effects and implications for organ maintenance therapy. Of the 524 patients who underwent transplantation, 387 were eligible for the study. Complete allele and two functional polymorphisms of ( and ) were analyzed in 148 transplanted patients and 146 controls. Increased recipient/donor allele mismatches correlate with an elevated risk of antibody-mediated rejection (X = 6.95; Log-rank=0.031). Notably, the genotype contributes to a significantly increased risk of antibody-mediated rejection (X = 13.44; Log-rank=0.001 and = 0.34; Log-rank=0.84). The combined effect of two allele mismatches and genotype shows the highest risk (X = 23.21; Log-rank<0.001). Most importantly, patients with and AA genotypes may respond less to mTOR inhibitor immunosuppressive therapy than Calcineurin inhibitors ( P=0.035; and ; P=0.002). Recipient/donor allele mismatches and specific variants, as well as their combinations, influence kidney transplant outcomes, providing insights for personalized treatment and enhancing graft survival.

Primary biliary cholangitis (PBC) is a rare autoimmune liver disease involving bile duct damage and fibrosis. This study explores the role of HLA-G, an immunomodulatory molecule crucial for immune tolerance, in PBC pathogenesis and treatment. A cohort of 166 PBC patients from Sardinia was compared to 180 healthy controls and 205 autoimmune hepatitis type 1 (AIH-1) patients. Plasma soluble HLA-G (sHLA-G) levels, alleles, and haplotypes were analyzed alongside clinical data, including therapy response to ursodeoxycholic acid. The UTR-1 haplotype was significantly more frequent in PBC patients than in controls (48.2% vs 34.3%, Pc= 0.0018). The extended haplotype was also strongly associated with PBC (23.2% vs 12.5% in controls, Pc = 0.008; 23.2% vs 6.6% in AIH-1, Pc= 2.6×10 ). PBC patients exhibited lower sHLA-G levels compared to controls and AIH-1 (9.1 U/mL vs 24.03 U/mL and 13.9 U/mL, respectively). Among carriers, sHLA-G levels were particularly reduced in PBC patients. The haplotype correlated with the lowest sHLA-G levels and poorer therapy response (60% vs 24.1%, P = 0.0001). These findings suggest HLA-G variants, especially , as potential biomarkers for PBC prognosis and treatment outcomes.

A large number of risk and protective factors have been identified during the SARS-CoV-2 pandemic which may influence the outcome of COVID-19. Among these, recent studies have explored the role of HLA-G molecules and their immunomodulatory effects in COVID-19, but there are very few reports exploring the genetic basis of these manifestations. The present study aims to investigate how host genetic factors, including gene polymorphisms and sHLA-G, can affect SARS-CoV-2 infection. We compared the immune-genetic and phenotypic characteristics between COVID-19 patients (n = 381) with varying degrees of severity of the disease and 420 healthy controls from Sardinia (Italy). HLA-G locus analysis showed that the extended haplotype was more prevalent in both COVID-19 patients and controls. In particular, this extended haplotype was more common among patients with mild symptoms than those with severe symptoms [22.7% 15.7%, OR = 0.634 (95% CI 0.440 - 0.913); P = 0.016]. Furthermore, the most significant polymorphism ( ) shows that the genotype frequency decreases gradually from 27.6% in paucisymptomatic patients to 15.9% in patients with severe symptoms (X = 7.095, P = 0.029), reaching the lowest frequency (7.0%) in ICU patients (X = 11.257, P = 0.004). However, no significant differences were observed for the soluble HLA-G levels in patients and controls. Finally, we showed that SARS-CoV-2 infection in the Sardinian population is also influenced by other genetic factors such as β-thalassemia trait ( C>T in the gene), -C C1+ group combination and the haplotype which exert a protective effect [P = 0.005, P = 0.001 and P = 0.026 respectively]. Conversely, the Neanderthal gene variant ( A>G) shows a detrimental consequence on the disease course [P = 0.001]. However, by using a logistic regression model, genotype was independent from the other significant variables [OR = 0.4 (95% CI 0.2 - 0.7), P = 6.5 x 10 ]. Our results reveal novel genetic variants which could potentially serve as biomarkers for disease prognosis and treatment, highlighting the importance of considering genetic factors in the management of COVID-19 patients.