Elevated plasma level of the glycolysis byproduct methylglyoxal on admission is an independent biomarker of mortality in ICU COVID-19 patients

Fasting plasma methylglyoxal concentrations are associated with higher numbers of circulating intermediate and non-classical monocytes but with lower activation of intermediate monocytes: the Maastricht Study

PURPOSE

Elevated methylglyoxal (MGO) levels and altered immune cell responses are observed in diabetes. MGO is thought to modulate immune cell activation. The current study investigated whether fasting or post-glucose-load plasma MGO concentrations are associated with circulating immune cell counts and activation in a large cohort study.

METHODS

696 participants of The Maastricht Study (age 60.3 ± 8.4 years, 51.9% women) underwent an oral glucose tolerance test (OGTT). Fasting and post-OGTT plasma MGO concentrations were measured using mass spectrometry. Numbers and activation of circulating immune cells at fasting state were quantified using flow cytometry. Activation scores were calculated by averaging individual marker z-scores for neutrophils (CD11b, CD11c, CD16) and classical, intermediate, and non-classical monocytes (CD11b, CD11c, CX3XR1, HLA-DR). Associations were analysed using multiple linear regression adjusted for potential confounders. Stratified analyses were performed for glucose metabolism status for associations between plasma MGO levels and immune cell counts.

RESULTS

Higher fasting plasma MGO concentrations were significantly associated with higher numbers of intermediate (β = 0.09 [95%CI 0.02; 0.17]) and non-classical monocytes (0.08 [0.002; 0.15]), but with lower activation scores for the intermediate monocytes (-0.14 [-0.22; -0.06]). Stratified analyses showed that positive associations between fasting plasma MGO levels and numbers of intermediate and non-classical monocytes appear only in participants with type 2 diabetes. Post-OGTT plasma MGO concentrations were not consistently associated with immune cells counts or activation.

CONCLUSION

Higher fasting plasma MGO concentrations are associated with higher intermediate and non-classical monocyte counts but with lower activation of intermediate monocytes.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Spike Protein S1 Induces Methylglyoxal-Derived Hydroimidazolone/Receptor for Advanced Glycation End Products (MG-H1/RAGE) Activation to Promote Inflammation in Human Bronchial BEAS-2B Cells

The pathogenesis of coronavirus disease 2019 (COVID-19) is associated with a hyperinflammatory response. The mechanisms of SARS-CoV-2-induced inflammation are scantly known. Methylglyoxal (MG) is a glycolysis-derived byproduct endowed with a potent glycating action, leading to the formation of advanced glycation end products (AGEs), the main one being MG-H1. MG-H1 exerts strong pro-inflammatory effects, frequently mediated by the receptor for AGEs (RAGE). Here, we investigated the involvement of the MG-H1/RAGE axis as a potential novel mechanism in SARS-CoV-2-induced inflammation by resorting to human bronchial BEAS-2B and alveolar A549 epithelial cells, expressing different levels of the ACE2 receptor (R), exposed to SARS-CoV-2 spike protein 1 (S1). Interestingly, we found in BEAS-2B cells that do not express ACE2-R that S1 exerted a pro-inflammatory action through a novel MG-H1/RAGE-based pathway. MG-H1 levels, RAGE and IL-1β expression levels in nasopharyngeal swabs from SARS-CoV-2-positive and -negative individuals, as well as glyoxalase 1 expression, the major scavenging enzyme of MG, seem to support the results obtained in vitro. Altogether, our findings reveal a novel mechanism involved in the inflammation triggered by S1, paving the way for the study of the MG-H1/RAGE inflammatory axis in SARS-CoV-2 infection as a potential therapeutic target to mitigate COVID-19-associated pathogenic inflammation.

The oldest unvaccinated Covid-19 survivors in South America

BACKGROUND

Although older adults are at a high risk of severe or critical Covid-19, there are many cases of unvaccinated centenarians who had a silent infection or recovered from mild or moderate Covid-19. We studied three Brazilian supercentenarians, older than 110 years, who survived Covid-19 in 2020 before being vaccinated.

RESULTS

Despite their advanced age, humoral immune response analysis showed that these individuals displayed robust levels of IgG and neutralizing antibodies (NAbs) against SARS-CoV-2. Enrichment of plasma proteins and metabolites related to innate immune response and host defense was also observed. None presented autoantibodies (auto-Abs) to type I interferon (IFN). Furthermore, these supercentenarians do not carry rare variants in genes underlying the known inborn errors of immunity, including particular inborn errors of type I IFN.

CONCLUSION

These observations suggest that their Covid-19 resilience might be a combination of their genetic background and their innate and adaptive immunity.