Immunoglobulin A response to SARS-CoV-2 infection and immunity

mRNA COVID-19 vaccines induce superior IgA titers in cancer patients compared to viral vector vaccines: Implications for immunization strategies

OBJECTIVES

IgA antibodies are involved in mucosal immunity and eliminate pathogens immediately at the point of entry. Vaccine-induced IgA antibodies could contribute to an additional layer of protection against SARS-CoV-2 for infection prone cancer patients. This might be particularly relevant for cancer patients as they mount reduced IgG antibody titers after dual-dose BNT162b2 COVID-19 vaccination and even lower responses after double-dose ChAdOx1 vaccination, compared to healthy individuals. However, data on vaccine-induced IgA antibodies are scarce, especially in cancer patients.

METHODS

This study compares SARS-CoV-2 anti-S1 IgA antibodies after dual-dose BNT162b2 vs ChAdOx1 vaccination in cancer patients. SARS-CoV-2 anti-S1 IgA antibodies were quantified in serum samples collected 7 days after second vaccination dose (N=213) (IEQ-CoVS1RBD-IgA-1-RB ELISA kit, RayBiotech) and analyzed with colorimetric detection. Additionally correlations with different aspects of humoral immunity were assessed (neutralizing and IgG antibodies).

RESULTS

Significant lower anti-S1 IgA antibody titers were reported in cancer patients after dual-dose ChAdOx1 compared to BNT162b2 vaccination. Moreover, cancer patients that received dual-dose BNT162b2 vaccination had a significant 16.44 fold increased chance to mount detectable IgA antibodies compared to patients receiving ChAdOx1 vaccination.

CONCLUSION

These findings highlight the potential role of boosters or alternative strategies to sustain mucosal immunity.

Bacterial lysates in modifying sIgA levels in the upper respiratory tract in COVID-19 patients

A great deal of evidence has accumulated suggesting an important role of mucosal immunity not only in preventing COVID-19 but also in the pathogenesis of this infection. The aim of the study was to evaluate the levels of secretory immunoglobulin A (sIgA) in different compartments of the upper respiratory tract in COVID-19 patients in relation to the severity of the disease and treatment with a bacteria-based immunomodulating agent (Immunovac VP4). The titers of sIgA were determined by ELISA in nasal epithelial swabs, pharyngeal swabs, and salivary gland secretions at baseline and on days 14 and 30 of treatment. The levels of nasal, pharyngeal and salivary sIgA were significantly lower in more severe patients (subgroup A) than in less severe patients (subgroup B), p < 0.01. In subgroup A, the patients who received Immunovac VP4 had higher pharyngeal sIgA levels in convalescent period than those who did not receive the therapy p < 0.05. In subgroup B patients, an increase in immunoglobulin levels was observed from baseline to day 14 of treatment whether they received the add-on therapy or not, p < 0.01. On day 30 of treatment, the sIgA levels in the standard treatment group, however, decreased, while the patients receiving the immunomodulating agent maintained high sIgA levels, p < 0.05. Oxygen saturation significantly increased by day 14 in both groups, p < 0.001. However, it was higher in the Immunovac VP4 group than in the standard treatment group, p < 0.01. Thus, addition of a bacterial lysate-based immunomodulating agent to the treatment regimen for moderate-to-severe COVID-19 induces the production of pharyngeal and salivary sIgA. SIgA production is inversely correlated to CRP levels and percentage of lung involvement on CT scan and is directly correlated to SpO2 levels.

Genetic diversity of the immunoglobulin heavy chain locus in cohorts of patients affected with SARS-CoV-2

BACKGROUND

The Immunoglobulin Heavy Chain (IGH) genomic region is responsible for the production of circulating antibodies and warrants careful investigation for its association with COVID-19 characteristics. Multiple allelic variants within and across different IGH gene segments form a limited set of haplotypes. Previous studies have shown associations between some of these haplotypes and clinical outcomes of COVID-19. We typed 445 individuals of European ancestry, stratified for gender, age, and clinical status for 4 SNPs, two of which result in amino acid substitutions in IGHA2 and IGHG4, respectively. We analyzed associations at the single-locus level and for 4-loci haplotypes, inferred by phasing, after stratifying the overall cohort by gender, age, and disease severity.

RESULTS

Only weak evidence of significant differences between subgroups was obtained at the level of a single SNP. However, when the haplotypic data were analyzed for the young and old subgroups separately, uneven partitioning was observed regarding the occurrence of severe cases and Resistors. We then examined the cross-tabulation of disease severity in males and females, based on the presence of each haplotype in the genotype. Two haplotypes were underrepresented in young severe cases compared to old severe ones. The same two haplotypes were overrepresented among young Resistors. These findings provide stronger support for, the weak associations observed at the single locus level.

CONCLUSIONS

Two haplotypes seem to act as protective factors specifically in young individuals, counteracting the general increase in vulnerability with age. This observation aligns with stronger genetic effects seen in young patients for other susceptibility genes. Our findings complement previous research identifying specific genetic variants that influence COVID-19 susceptibility and severity, emphasizing the complex interplay between host genetics and viral infection outcomes. Our results are consistent with a potential causative role of IGH regulatory regions (e.g. HS1.2), which are flanked by the SNP set here analyzed.

A Possible Protective Effect of IgA Against Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) in Bronchoalveolar Lavage in COVID-19 Patients Admitted to Intensive Care Unit

SARS-CoV-2 infection induces a humoral immune response, producing virus-specific antibodies such as IgM, IgG, and IgA. IgA antibodies are present at mucosal sites, protecting against respiratory and other mucosal infections, including SARS-CoV-2, by neutralizing viruses or impeding attachment to epithelial cells. Since SARS-CoV-2 spreads through the nasopharynx, the specific IgAs of SARS-CoV-2 are produced quickly after infection, effectively contributing to virus neutralization. Dimeric IgA has been reported to be 10 to 15 times more potent than its equivalent IgG, suggesting that this isotype may be particularly interesting in developing new monoclonal antibodies and/or new vaccines efficiently neutralizing the virus at the mucosal sites. It is still unclear whether IgA antibodies in BAL might play a role in the disease course and if their presence may have a prognostic significance. However, a harmful effect on diseases with high IgA titers has been reported. This study evaluated mucosal-specific IgA and IgG profiles in BAL of patients with COVID-19 acute respiratory failure admitted to the ICU. We included 57 patients (41 males and 16 females), admitted to the ICU of the University of Foggia. We used a commercially available ELISA assay to evaluate the presence of SARS-CoV-2 IgG and IgA antibodies in plasma and BAL of the 57 hospitalized patients with severe COVID-19 respiratory failure. However, 40/57 BAL and plasma from infected patients were available for the ELISA test; the remaining specimens were unsuitable. IgG and IgA antibodies against SARS-CoV-2 were detectable in 37 (92.5%) and 40 (100%) plasma specimens, respectively. IgG antibodies were found in a single sample, while IgAs were detected in 19 of 40 BAL samples analyzed. Correlations between these parameters and patient outcomes reveal a signature associated with survival. Interestingly, a statistically significant inverse correlation was found between the mortality rate and the presence of IgA to SARS-CoV-2 in BAL specimens. None of the 19 patients with a positive IgA died, compared to 7 out of 12 patients with a negative IgA-BAL (p: <0.0004). Despite being limited in size, this study suggests a significant protective effect of mucosal immunity in COVID-19 patients, even in advanced disease stages, and a role of IgA in the defense against the virus, as well as the possible use of effective vaccines and therapeutic strategies based on IgA antibodies.

Immunoglobulins in COVID-19 pneumonia: from the acute phase to the recovery phase

BACKGROUND

COVID-19 pneumonia causes hyperinflammatory response that culminates in acute respiratory syndrome (ARDS) related to increased multiorgan dysfunction and mortality risk. Antiviral-neutralizing immunoglobulins production reflect the host humoral status and illness severity, and thus, immunoglobulin (Ig) circulating levels could be evidence of COVID-19 prognosis.

METHODS

The relationship among circulating immunoglobulins (IgA, IgG, IgM) and COVID-19 pneumonia was evaluated using clinical information and blood samples in a COVID-19 cohort composed by 320 individuals recruited during the acute phase and followed up to 4 to 8 weeks (n = 252) from the Spanish first to fourth waves.

RESULTS

COVID-19 pneumonia development depended on baseline Ig concentrations. Circulating IgA levels together with clinical features at acute phase was highly associated with COVID-19 pneumonia development. IgM was positively correlated with obesity (ρb = 0.156, P = 0.020), dyslipemia (ρb = 0.140, P = 0.029), COPD (ρb = 0.133, P = 0.037), cancer (ρb = 0.173, P = 0.007) and hypertension (ρb = 0.148, P = 0.020). Ig concentrations at recovery phase were related to COVID-19 treatments.

CONCLUSIONS

Our results provide valuable information on the dynamics of immunoglobulins upon SARS-CoV-2 infection or other similar viruses.