Polymorphisms in the MBL2 gene are associated with the plasma levels of MBL and the cytokines IL-6 and TNF-α in severe COVID-19

High nasopharyngeal and serum IL-6 levels and the - 573G > C polymorphism (rs1800796) are linked with the risk of severe COVID-19 in a Mexican population: a case‒control study

BACKGROUND

COVID-19 was the leading cause of death in Mexico between 2020 and 2021. SARS-CoV-2 infection varies widely among individuals and populations. Since variations in genes related to the immune response may play a role in the susceptibility to and outcome of COVID-19, the associations of gene polymorphisms (SNPs) of IL-6 (- 573G > C, rs1800796), TNF-α (- 308G > A, rs1800629), and IFN-γ (- 1615 C > T, rs2069705) with the expression levels of these proteins in the nasopharynx and serum were evaluated in a Mexican population with mild, severe, or critical COVID-19.

METHODS

A total of 560 COVID-19 patients (309 mild, 163 severe, and 88 critical cases) and 560 age- and sex-matched COVID-19-negative controls were recruited for this case‒control study. The selected SNPs were genotyped via allelic discrimination. Logistic regression analysis was conducted considering four models of inheritance, and ORs were determined for each genotypic variant, adjusting for associated comorbidities in the multivariate model. The nasopharyngeal mRNA expression levels of IL-6, IFN-γ and TNF-α were determined. The levels of IL-6, IFN-γ, IFN-α2, and TNF-α in the serum were quantified. Significant differences were assessed via the Wilcoxon Mann‒Whitney U test.

RESULTS

The C allele of the IL-6 - 573 SNP was associated with a greater risk of mild and severe COVID-19 (OR: 2.3, CI: 1.897-2.838, p = 0.0001; and OR: 1.5, CI: 1.167-1.949, p = 0.002, respectively), whereas the A allele of the TNF-α - 308 SNP and the T allele of the IFN-γ - 1615 SNP were shown protective roles against severe COVID-19 (OR: 0.3, CI: 0.189-0.537, p = 0.0001; and OR: 0.7, CI: 0.563-1.006, p = 0.05) and against critical COVID-19 (OR: 0.3, CI: 0.158-0.640, p = 0.001; and OR: 0.4, CI: 0.290-0.678, p = 0.0001), adjusting for diabetes and hypertension. Nasopharyngeal IL-6 expression levels were lower in mild COVID-19 patients (p = 0.001) than in critical patients (p = 0.005). Serum IL-6 levels were significantly elevated in the critical cases (p = 0.01).

CONCLUSIONS

Our results revealed that the IL-6 - 573 G > C SNP and increased IL-6 nasopharyngeal and serum levels are associated with the risk of severe COVID-19 in a Mexican population.

Genetics of Long COVID: Exploring the Molecular Drivers of Persistent Pulmonary Vascular Disease Symptoms

Background/ Objectives: Long COVID or post-acute sequelae of SARS-CoV-2 infection (PASC) are symptoms that manifest despite passing the acute infection phase. These manifestations encompass a wide range of symptoms, the most common being fatigue, shortness of breath, and cognitive dysfunction. Genetic predisposition is clearly involved in the susceptibility of individuals to developing these persistent symptoms and the variation in the severity and forms. This review summarizes the role of genetic factors and gene polymorphisms in the development of major pulmonary vascular disorders associated with long COVID. Methods: A comprehensive review of current literature was conducted to examine the genetic contributions to pulmonary complications following SARS-CoV-2 infection. Studies investigating genetic polymorphisms linked to pulmonary hypertension, pulmonary thromboembolism, and pulmonary vascular endothelialitis were reviewed and summarized. Results: Findings show that specific genetic variants contribute to increased susceptibility to pulmonary vascular complications in long COVID patients. Variants associated with endothelial dysfunction, coagulation pathways, and inflammatory responses have been implicated in the development of pulmonary hypertension and thromboembolic events. Genetic predispositions influencing vascular integrity and immune responses appear to influence disease severity and progression. Conclusions: Understanding these mechanisms and genetic predispositions could pave the way for targeted therapeutic interventions to alleviate the burden on patients experiencing long COVID.

Unraveling the impact of SARS-CoV-2 mutations on immunity: insights from innate immune recognition to antibody and T cell responses

Throughout the COVID-19 pandemic, the emergence of new viral variants has challenged public health efforts, often evading antibody responses generated by infections and vaccinations. This immune escape has led to waves of breakthrough infections, raising questions about the efficacy and durability of immune protection. Here we focus on the impact of SARS-CoV-2 Delta and Omicron spike mutations on ACE-2 receptor binding, protein stability, and immune response evasion. Delta and Omicron variants had 3-5 times higher binding affinities to ACE-2 than the ancestral strain (KDwt = 23.4 nM, KDDelta = 8.08 nM, KDBA.1 = 4.77 nM, KDBA.2 = 4.47 nM). The pattern recognition molecule mannose-binding lectin (MBL) has been shown to recognize the spike protein. Here we found that MBL binding remained largely unchanged across the variants, even after introducing mutations at single glycan sites. Although MBL binding decreased post-vaccination, it increased by 2.6-fold upon IgG depletion, suggesting a compensatory or redundant role in immune recognition. Notably, we identified two glycan sites (N717 and N801) as potentially essential for the structural integrity of the spike protein. We also evaluated the antibody and T cell responses. Neutralization by serum immunoglobulins was predominantly mediated by IgG rather than IgA and was markedly impaired against the Delta (5.8-fold decrease) and Omicron variants BA.1 (17.4-fold) and BA.2 (14.2-fold). T cell responses, initially conserved, waned rapidly within 3 months post-Omicron infection. Our data suggests that immune imprinting may have hindered antibody and T cell responses toward the variants. Overall, despite decreased antibody neutralization, MBL recognition and T cell responses were generally unaffected by the variants. These findings extend our understanding of the complex interplay between viral adaptation and immune response, underscoring the importance of considering MBL interactions, immune imprinting, and viral evolution dynamics in developing new vaccine and treatment strategies.

Impact of Gene Modifiers on Cystic Fibrosis Phenotypic Profiles: A Systematic Review

Cystic fibrosis (CF) is a complex monogenic disorder with a large variability in disease severity. Growing evidence suggests that the variation observed depends not only on variations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene but also on modifier genes. Utilizing five databases (including CINAHL, PubMed, Science Direct, Scopus, and Web of Science), a systematic review was conducted to examine the current literature on the known impacts of genomic variations in modifier genes on the CF disease progression, severity, and therapeutic response. A total of 70 full-text articles describing over 80 gene modifiers associated with CF were selected. The modifier genes included genes associated with the CFTR interactome, the inflammatory response, microbial profiles, and other genes affecting the critical physiological pathways of multiple organ systems, such as the respiratory and gastrointestinal systems. Limitations of the existing literature embrace the lack of clinical studies investigating pharmacogenetic impacts and the significance of gene modifiers on the CF clinical picture, including a limited number of replication and validation studies. Further investigations into other potential gene modifiers using genome-wide association studies are needed to critically explore new therapeutic targets and provide a better understanding of the CF disease phenotype under specific drug treatments.

Equal Maintenance of Anti-SARS-CoV-2 Antibody Levels Induced by Heterologous and Homologous Regimens of the BNT162b2, ChAdOx1, CoronaVac and Ad26.COV2.S Vaccines: A Longitudinal Study Up to the 4th Dose of Booster

Several technological approaches have been used to develop vaccines against COVID-19, including those based on inactivated viruses, viral vectors, and mRNA. This study aimed to monitor the maintenance of anti-SARS-CoV-2 antibodies in individuals from Brazil according to the primary vaccination regimen, as follows: BNT162b2 (group 1; 22) and ChAdOx1 (group 2; 18). Everyone received BNT162b2 in the first booster while in the second booster CoronaVac, Ad26.COV2.S, or BNT162b2. Blood samples were collected from 2021 to 2023 to analyze specific RBD (ELISA) and neutralizing antibodies (PRNT50). We observed a progressive increase in anti-RBD and neutralizing antibodies in each subsequent dose, remaining at high titers until the end of follow-up. Group 1 had higher anti-RBD antibody titers than group 2 after beginning the primary regimen, with significant differences after the 2nd and 3rd doses. Group 2 showed a more expressive increase after the first booster with BNT162B2 (heterologous booster). Group 2 also presented high levels of neutralizing antibodies against the Gamma and Delta variants until five months after the second booster. In conclusion, the circulating levels of anti-RBD and neutralizing antibodies against the two variants of SARS-CoV-2 were durable even five months after the 4th dose, suggesting that periodic booster vaccinations (homologous or heterologous) induced long-lasting immunity.

[Genetic factors associated with long COVID]

INTRODUCTION

The variability in expression and evolution of COVID is not completely explained by clinical factors. In fact, genetic factors play an important role. Moreover, it is unknown whether the genetic factor that contribute to susceptibility and severity are also involved in the onset and evolution of long-COVID. The objective of this review is to gather information from literature to understand which genetic factors are involved in the onset of persistent COVID.

MATERIAL AND METHODS

Systematic review in PubMed and bioRxiv and medRxiv repositories based on MeSH-descriptors and MeSH-terms related to COVID and genetic factors. Using these terms 2715 articles were pooled. An initial screening performed by authors independently, selected 205 articles of interest. A final deeper screening a total of 85 articles were chosen for complete reading and summarized in this review.

RESULTS

Although ACE2 and TMPSS6 are involved in COVID susceptibility, their involvement in long-COVID has not been found. On the other hand, the severity of the disease and the onset of long-COVID has been associated with different genes involved in the inflammatory and immune response. Particularly interesting has been the association found with the FOXP4 locus.

CONCLUSIONS

Although studies on long-COVID are insufficient to fully comprehend the cause, it is clear that the current identified genetic factors do not fully explain the progression and onset of long-COVID. Other factors such as polygenic action, pleiotropic genes, the microbiota and epigenetic changes must be considered and studied.

Severe COVID-19 and long COVID are associated with high expression of STING, cGAS and IFN-α

The cGAS-STING pathway appears to contribute to dysregulated inflammation during coronavirus disease 2019 (COVID-19); however, inflammatory factors related to long COVID are still being investigated. In the present study, we evaluated the association of cGAS and STING gene expression levels and plasma IFN-α, TNF-α and IL-6 levels with COVID-19 severity in acute infection and long COVID, based on analysis of blood samples from 148 individuals, 87 with acute COVID-19 and 61 in the post-COVID-19 period. Quantification of gene expression was performed by real-time PCR, and cytokine levels were quantified by ELISA and flow cytometry. In acute COVID-19, cGAS, STING, IFN-α, TNF-α, and IL-6 levels were higher in patients with severe disease than in those with nonsevere manifestations (p < 0.05). Long COVID was associated with elevated cGAS, STING and IFN-α levels (p < 0.05). Activation of the cGAS-STING pathway may contribute to an intense systemic inflammatory state in severe COVID-19 and, after infection resolution, induce an autoinflammatory disease in some tissues, resulting in long COVID.

Emerging role of complement in COVID-19 and other respiratory virus diseases

The complement system, a key component of innate immunity, provides the first line of defense against bacterial infection; however, the COVID-19 pandemic has revealed that it may also engender severe complications in the context of viral respiratory disease. Here, we review the mechanisms of complement activation and regulation and explore their roles in both protecting against infection and exacerbating disease. We discuss emerging evidence related to complement-targeted therapeutics in COVID-19 and compare the role of the complement in other respiratory viral diseases like influenza and respiratory syncytial virus. We review recent mechanistic studies and animal models that can be used for further investigation. Novel knockout studies are proposed to better understand the nuances of the activation of the complement system in respiratory viral diseases.

High production MBL2 polymorphisms protect against COVID-19 complications in critically ill patients: A retrospective cohort study

Mannose-binding lectin (MBL) binds to SARS-CoV-2, inhibits infection of susceptible cells, and activates the complement system via the lectin pathway. In this study, we investigated the association of MBL2 polymorphisms with the risk of hospitalization and clinical worsening in patients with COVID-19. A total of 550 patients with COVID-19 were included (94 non-hospitalized and 456 hospitalized). Polymorphisms in MBL2 exon 1 (codons 52, 54 and 57) and promoter region (-550, -221, and +4) were determined by real-time PCR. MBL and complement proteins were measured by Luminex. A higher frequency of the H/H genotype and the HYPA haplotype was observed in non-hospitalized patients when compared to hospitalized. In addition, critically ill patients carrying haplotypes associated with high MBL levels (HYPA/HYPA + HYPA/LYPA + HYPA/LYQA + LYPA/LYQA + LYPA/LYPA + LYQA/LYQA + LXPA/HYPA + LXPA/LYQA + LXPA/LYPA) were protected against lower oxygen saturation levels (P = 0.02), use of invasive ventilation use (P = 0.02, OR 0.38), and shock (P = 0.01, OR 0.40), independent of other potential confounders adjusted by multivariate analysis. Our results suggest that variants in MBL2 associated with high MBL levels may play a protective role in the clinical course of COVID-19.

Interaction Between Genetic Susceptibility and COVID-19 Pathogenesis in Pediatric Multisystem Inflammatory Disorders: The Role of Immune Responses

Numerous studies have highlighted the emergence of coronavirus disease (COVID-19) symptoms reminiscent of Kawasaki disease in children, including fever, heightened multisystem inflammation, and multiorgan involvement, posing a life-threatening complication. Consequently, extensive research endeavors in pediatric have aimed to elucidate the intricate relationship between COVID-19 infection and the immune system. COVID-19 profoundly impacts immune cells, culminating in a cytokine storm that particularly inflicts damage on the pulmonary system. The gravity and vulnerability to COVID-19 are closely intertwined with the vigor of the immune response. In this context, the human leukocyte antigen (HLA) molecule assumes pivotal significance in shaping immune responses. Genetic scrutiny of HLA has unveiled the presence of at least one deleterious allele in children afflicted with multisystem inflammatory syndrome in children (MIS-C). Furthermore, research has demonstrated that COVID-19 exploits the angiotensin-converting enzyme 2 (ACE-2) receptor, transmembrane serine protease type 2, and various other genes to gain entry into host cells, with individuals harboring ACE-2 polymorphisms being at higher risk. Pediatric studies have employed diverse genetic methodologies, such as genome-wide association studies (GWAS) and whole exome sequencing, to scrutinize target genes. These investigations have pinpointed two specific genomic loci linked to the severity and susceptibility of COVID-19, with the HLA locus emerging as a notable risk factor. In this comprehensive review article, we endeavor to assess the available evidence and consolidate data, offering insights into current clinical practices and delineating avenues for future research. Our objective is to advance early diagnosis, stabilization, and appropriate management strategies to mitigate genetic susceptibility's impact on the incidence of COVID-19 in pediatric patients with multisystem inflammation.

The MBL2 genotype relates to COVID-19 severity and may help to select the optimal therapy

OBJECTIVES

Sars-CoV-2 acute infection is clinically heterogeneous, ranging from asymptomatic cases to patients with a severe, systemic clinical course. Among the involved factors age and preexisting morbidities play a major role; genetic host susceptibility contributes to modulating the clinical expression and outcome of the disease. Mannose-binding lectin is an acute-phase protein that activates the lectin-complement pathway, promotes opsonophagocytosis and modulates inflammation, and is involved in several bacterial and viral infections in humans. Understanding its role in Sars-CoV-2 infection could help select a better therapy.

METHODS

We studied MBL2 haplotypes in 419 patients with acute COVID-19 in comparison to the general population and related the haplotypes to clinical and laboratory markers of severity.

RESULTS

We recorded an enhanced frequency of MBL2 null alleles in patients with severe acute COVID-19. The homozygous null genotypes were significantly more frequent in patients with advanced WHO score 4-7 (OR of about 4) and related to more severe inflammation, neutrophilia, and lymphopenia.

CONCLUSIONS

Subjects with a defective MBL2 genotype (i.e., 0/0) are predisposed to a more severe acute Sars-CoV-2 infection; they may benefit from early replacement therapy with recombinant MBL. Furthermore, a subset of subjects with the A/A MBL genotype develop a relevant increase of serum MBL during the early phases of the disease and develop a more severe pulmonary disease; in these patients, the targeting of the complement may help. Therefore, COVID-19 patients should be tested at hospitalization with serum MBL analysis and MBL2 genotype, to define the optimal therapy.