Soil-transmitted helminths infect billions of people globally, particularly those residing in low- and middle-income regions with poor environmental sanitation and high levels of air and water pollution. Helminths display potent immunomodulatory activity by activating T helper type 2 (Th2) anti-inflammatory and Th3 regulatory immune responses. The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the virus that causes Coronavirus disease 2019 (COVID-19), can exacerbate Th1/Th17 pro-inflammatory cytokine production in humans, leading to a cytokine storm. Air pollutants (particulate matter, oxygen radicals, hydrocarbons and volatile organic compounds) and water pollutants (metals and organic chemicals) can also intensify Th1/Th17 immune response and could exacerbate SARS-CoV-2 related respiratory distress and failure. The present review focused on the epidemiology of SARS-CoV-2, helminths and fine particulate matter 2.5 µm or less in diameter (PM 2.5 ) air pollution exposure in helminth endemic regions, the possible immunomodulatory activity of helminths against SARS-CoV-2 hyper-inflammatory immune response, and whether air and water pollutants can further exacerbate SARS-CoV-2 related cytokine storm and in the process hinder helminths immunomodulatory functionality. Helminth Th2/Th3 immune response is associated with reductions in lung inflammation and damage, and decreased expression levels of angiotensin-converting enzyme 2 (ACE2) receptors (SARS-CoV-2 uses the ACE2 receptors to infect cells and associated with extensive lung damage). However, air pollutants are associated with overexpression of ACE2 receptors in the epithelial cell surface of the respiratory tract and exhaustion of Th2 immune response. Helminth-induced immunosuppression activity reduces vaccination efficacy, and diminishes vital Th1 cytokine production immune responses that are crucial for combating early stage infections. This could be reversed by continuous air pollution exposure which is known to intensify Th1 pro-inflammatory cytokine production to a point where the immunosuppressive activities of helminths could be hindered. Again, suppressed activities of helminths can also be disadvantageous against SARS-CoV-2 inflammatory response. This “yin and yang” approach seems complex and requires more understanding. Further studies are warranted in a cohort of SARS-CoV-2 infected individuals residing in helminths and air pollution endemic regions to offer more insights, and to impact mass periodic deworming programmes and environmental health policies.
【저자키워드】 Cytokine storm, COVID-19, Coronavirus disease 2019, SARS-CoV-2, Severe acute respiratory syndrome coronavirus 2, ACE2, angiotensin-converting enzyme 2, GM-CSF, granulocyte-macrophage colony-stimulating factor, IL, interleukin, MIP, macrophage inflammatory protein, Environmental pollution, IGG, immunoglobulin g, Tregs, regulatory T cells, VEGF, Vascular endothelial growth factor, TMPRSS2, Transmembrane Protease Serine 2, CCL, chemokine (C-C motif) ligand, G-CSF, granulocyte colony-stimulating factor, IFN-γ, interferon gamma, IgE, immunoglobulin E, CXCL, Chemokine (C-X-C motif) ligand, RANTES, Regulated upon Activation, Normal T Cell Expressed and Presumably Secreted, SARS-CoV-2/ COVID-19, Th1/Th17-induced pro-inflammatory immune response, Helminth-induced Th2/Th3 anti-inflammatory immune response, Immunomodulatory activity of helminths, ADCC, antibody-dependent cellular cytotoxicity, AREG, amphiregulin, AT1/AT2, alveolar type 1/2, BCG, bacillus Calmette–Guérin, CO, carbon monoxide, EGF, epidermal growth factor, MCP, monocyte chemotactic protein, NO2, nitrogen dioxide, O3, ozone, PDGF, platelet-derived growth factor, PM, particulate matter, sCD40L, soluble CD40 ligand, SDF1, stromal cell-derived factor 1, sICAM-1, soluble intercellular adhesion molecule-1, SO2, sulphur dioxide, sVCAM-1, soluble Vascular Cell Adhesion Molecule-1, TGF-β, transforming growth factor beta, Th1/Th17, T helper cell 1/17, TNF-α, tumour necrosis factor alpha, TSLP, thymic stromal lymphopoietin,