CXCR2 signaling and host defense following coronavirus-induced encephalomyelitis

Chronic Exposure to the Food Additive tBHQ Modulates Expression of Genes Related to SARS-CoV-2 and Influenza Viruses

Background. tert-butylhydroquinone (tBHQ) is an antioxidant commonly used as a food additive. Studies suggest that tBHQ could modulate immune responses to influenza and SARS-CoV-2 infection. In our transcriptomic analysis we explored the molecular mechanisms behind tBHQ’s modulatory properties and the relationships to respiratory viral infections. Methods. tBHQ was administered per os to BALB/c mice (1.5% [w/w]) for 20 days. Splenic T cells were isolated with magnetic separation and subjected to transcriptomic analysis. Gene-set enrichment analysis and g:Profiler was conducted to provide a functional interpretation of significantly changed genes. Further analysis for AHR/NRF2 binding sites was performed with GeneHancer. Results. In CD4⁺ cells, we found significantly altered expression of 269 genes by tBHQ. Of them, many had relevance in influenza infection such as genes responsible for virus entry (Anxa1/2, Cd14), interferon signaling (Dusp10, Tnfsf13), or prostaglandin synthesis (Ptgs1/2). In SARS-CoV-2 infections, interferon signaling (Ifitm1), proteolytic enzymes (CtsB), and also cell-surface proteins (Cd14, Cd151) were among the prominent alterations after tBHQ exposure. Of these genes, many had one or more binding sites for AHR and NRF2, two major xenosensors triggered by tBHQ. Conclusions. Our results strongly suggest that a common food additive, tBHQ, can modulate virus-dependent processes in both influenza and SARS-CoV-2 infections.

Neurological involvement of COVID-19: from neuroinvasion and neuroimmune crosstalk to long-term consequences

As the coronavirus disease 2019 (COVID-19) pandemic continues to be a multidimensional threat to humanity, more evidence of neurological involvement associated with it has emerged. Neuroimmune interaction may prove to be important not only in the pathogenesis of neurological manifestations but also to prevent systemic hyperinflammation. In this review, we summarize reports of COVID-19 cases with neurological involvement, followed by discussion of possible routes of entry, immune responses against coronavirus infection in the central nervous system and mechanisms of nerve degeneration due to viral infection and immune responses. Possible mechanisms for neuroprotection and virus-associated neurological consequences are also discussed.

Transcriptional Regulation of CXCL5 in HIV-1-Infected Macrophages and Its Functional Consequences on CNS Pathology

Human immunodeficiency virus-1 (HIV-1)-infected monocytes/macrophages and microglia release increased levels of proinflammatory cytokines and chemokines, including ELR+ (containing glutamic acid-leucine-arginine motif) chemokines. To investigate the role of HIV-1 infection on chemokine regulation, monocyte-derived macrophages (MDMs) from normal donors were infected with HIV-1 and the expression of chemokines and their downstream biological functions were evaluated. Among the tested chemokines, CXCL5 was upregulated significantly both at the mRNA and protein level in the HIV-1-infected MDMs compared with mock-infected cultures. Upregulation of CXCL5 in the HIV-1-infected MDMs is, in part, regulated by increased interleukin-1β (IL-1β) production and phosphorylation of ERK1/2. Functional analyses indicate that HIV-1-induced overexpression of CXCL5 has enhanced the ability to attract neutrophils, as observed by chemotaxis assay. However, exposure of NT2, SH-SY5Y cells, and primary neurons to HIV-1-infected MDM supernatants resulted in cell death that was not rescued by anti-CXCL5 antibody suggesting that CXCL5 does not have direct effect on neuronal death. Together, these results suggest that the increased level of CXCL5 in tissue compartments, including the central nervous system of HIV-1-infected individuals might alter the inflammatory response through the infiltration of neutrophils into tissue compartment, thus causing secondary effects on resident cells.

ELR(+) chemokine signaling in host defense and disease in a viral model of central nervous system disease

Intracranial infection of the neurotropic JHM strain of mouse hepatitis virus (JHMV) into the central nervous system (CNS) of susceptible strains of mice results in an acute encephalomyelitis, accompanied by viral replication in glial cells and robust infiltration of virus-specific T cells that contribute to host defense through cytokine secretion and cytolytic activity. Mice surviving the acute stage of disease develop an immune-mediated demyelinating disease, characterized by viral persistence in white matter tracts and a chronic neuroinflammatory response dominated by T cells and macrophages. Chemokines and their corresponding chemokine receptors are dynamically expressed throughout viral infection of the CNS, influencing neuroinflammation by regulating immune cell infltration and glial biology. This review is focused upon the pleiotropic chemokine receptor CXCR2 and its effects upon neutrophils and oligodendrocytes during JHMV infection and a number of other models of CNS inflammation.