COVID-19: Can the symptomatic SARS-CoV-2 infection affect the homeostasis of the gut-brain-microbiota axis?

Abstract

COVID-19 is associated with acute and lethal pneumonia, causing the severe acute respiratory syndrome (SARS), which is not confined to the respiratory tract, as demonstrated by clinical evidence of the involvement of multiple organs, including the central nervous system (CNS). In this context, we hypothesized that both oligosymptomatic and symptomatic patients present an imbalance in the microbiota-gut (immune system) and nervous system axis, worsening the clinical picture. The brain constantly receives a direct and indirect influence from the intestine, more specifically from the immune system and intestinal microbiota. The presence of SARS-CoV-2 in the intestine and CNS, can contribute to both neurological disorders and gut immune system imbalance, events potentialized by an intestinal microbiota dysbiosis, aggravating the patient’s condition and causing more prolonged harmful effects.

Potential beneficial role of probiotics on the outcome of COVID-19 patients: An evolving perspective

“…Myelin loss is associated with anxiety, depression, and decreased sociability. Perhaps this is a probable explanation for the neuropsychiatric manifestations [ 18 , 26 , 27 ].…”

The Role of the Gastrointestinal System in Neuroinvasion by SARS-CoV-2

“…Studies have shown that glial cells and neurons in the central nervous system can express ACE2, which mediates the entry of viruses into glial cells, resulting in neurological symptoms (Belkaid and Harrison, 2017). Therefore, we propose that SARS-CoV-2 can retrogradely invade the glial cells of the central nervous system through the intestinal nervous system after invading the gastrointestinal system, causing neurological symptoms (Chaves Andrade et al, 2020). Thus, treatment measures, such as vagus nerve stimulation, may inhibit the neuroinvasion of COVID-19 (Chaves Andrade et al, 2020;Esposito et al, 2020).…”

“…In addition, a series of symptoms were observed in patients with COVID-19, including a broad range of neurological complications such as headache, ischemic stroke, disturbance of consciousness, and encephalitis/meningitis, indicating that SARS-CoV-2 could invade the brain (DosSantos et al, 2020;Meinhardt et al, 2021). In addition, in many case reports, other coronaviruses of the Betacoronavirus genus, such as SARS-CoV-1 and MERS-CoV, exhibited a neuroinvasive and neurovirulent profile (Chaves Andrade et al, 2020;DosSantos et al, 2020).…”

“…After the SARS-CoV-2 invades the gastrointestinal system, it can also reach the central nervous system through direct neuroinvasion or indirect immune activation of the intestinal nervous system or through the afferents of the intestinal vagus nerve (Bostanciklioglu, 2020). Chaves Andrade et al hypothesized for the first time that the symptoms initially appearing in the nervous system, such as headaches, disturbance of consciousness, and sensory abnormalities, might be subjective; however, more serious symptoms, such as disturbance of consciousness, seizures, and strokes, might occur during infection and inflammation (Chaves Andrade et al, 2020). Studies have shown that glial cells and neurons in the central nervous system can express ACE2, which mediates the entry of viruses into glial cells, resulting in neurological symptoms (Belkaid and Harrison, 2017).…”

COVID-19 and the digestive system: A comprehensive review

“…It also regulates the levels of antimicrobial peptides that affect the composition of the gut microbiota, leading to increased sensitivity to intestinal inflammation and epithelial dysfunction[ 106 ]. Thus, this viral infection might affect the homeostasis of the gut-brain axis through the intestinal microbiota[ 103 , 107 ]. However, further investigations are needed to clarify whether the dysbiosis is specific to SARS-CoV-2 infection or a consequence of critical illness.…”