Long COVID and the Neuroendocrinology of Microbial Translocation Outside the GI Tract: Some Treatment Strategies

Abstract

Similar to previous pandemics, COVID-19 has been succeeded by well-documented post-infectious sequelae, including chronic fatigue, cough, shortness of breath, myalgia, and concentration difficulties, which may last 5 to 12 weeks or longer after the acute phase of illness. Both the psychological stress of SARS-CoV-2 infection and being diagnosed with COVID-19 can upregulate cortisol, a stress hormone that disrupts the efferocytosis effectors, macrophages, and natural killer cells, leading to the excessive accumulation of senescent cells and disruption of biological barriers. This has been well-established in cancer patients who often experience unrelenting fatigue as well as gut and blood–brain barrier dysfunction upon treatment with senescence-inducing radiation or chemotherapy. In our previous research from 2020 and 2021, we linked COVID-19 to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) via angiotensin II upregulation, premature endothelial senescence, intestinal barrier dysfunction, and microbial translocation from the gastrointestinal tract into the systemic circulation. In 2021 and 2022, these hypotheses were validated and SARS-CoV-2-induced cellular senescence as well as microbial translocation were documented in both acute SARS-CoV-2 infection, long COVID, and ME/CFS, connecting intestinal barrier dysfunction to disabling fatigue and specific infectious events. The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID. To accomplish this goal, we examine the role of intestinal and blood–brain barriers in long COVID and other illnesses typified by chronic fatigue, with a special emphasis on commensal microbes functioning as viral reservoirs. Furthermore, we discuss the role of SARS-CoV-2/Mycoplasma coinfection in dysfunctional efferocytosis, emphasizing some potential novel treatment strategies, including the use of senotherapeutic drugs, HMGB1 inhibitors, Toll-like receptor 4 (TLR4) blockers, and membrane lipid replacement.

Microbiome and intestinal pathophysiology in post-acute sequelae of COVID-19

“…74 It is reported the important role of angiotensin II in SARS-CoV-2 infections for the COVID-19 up-regulated ANG II could disrupt efferocytosis inducing endothelial cell senescence and vascular barrier dysfunction via angiotensin II type 1 receptors. 72 , 75 Taken together, disrupted barrier functions are related to the observed pathophysiological changes in long COVID.…”

“… 70 SARS-CoV-2, like many other viruses, could enhance infectivity by usurping both physiological cell–cell fusion and efferocytosis, disrupting biological barriers. 71 , 72 , 73 For instance, SARS-CoV-2 was found to thrive in infected cells and likely inhibits their clearance and causes inflammation and barrier dysfunction. 74 It is reported the important role of angiotensin II in SARS-CoV-2 infections for the COVID-19 up-regulated ANG II could disrupt efferocytosis inducing endothelial cell senescence and vascular barrier dysfunction via angiotensin II type 1 receptors.…”

A Narrative Review on Gut Microbiome Disturbances and Microbial Preparations in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Implications for Long COVID

“…In summary, research to date indicate that probiotics, especially lactobacillus, may be beneficial in reducing GI symptoms in patients with ME/CFS and long COVID [ 2 , 124 ]. The immunoregulatory properties of probiotics may help to restore the perturbed composition of gut microbiota and dysbiosis, which could reduce symptom severity (linked to the reduced abundance of butyrate producing bacteria [ 41 ]).…”

Six Decades of Dopamine Hypothesis: Is Aryl Hydrocarbon Receptor the New D2?

“…Furthermore, γ-Aminobutyric acid (GABA)-generating Pseudomonas fluorescens may, upon migration into host systemic circulation, elicit anti-GABA antibodies, immunoglobulins documented in patients with SCZ [41,42]. As this topic was discussed elsewhere, it will not be explored in more detail here [183].…”