Microbiota and their Influence in the Human Body

Abstract

Scientists have invested considerable resources in the study of the microbiota of the human body. These microorganisms play pivotal roles in immunity and disease. Of which, probiotics are live beneficial microorganisms that keep your intestinal or lung microbiota healthy, and occupy a special role in combating the infections. Thus, it is critical to understand their contributions to these processes. Technology can facilitate advanced studies of the microbiota, including how it develops and its positive and negatives effects on the immune system. This paper investigates how several factors (e.g. birth delivery mode, metabolic activities, types of microorganisms, and immune system interactions) affect the microbiota, particularly in early life. The paper also discusses how gastrointestinal microbes in particular may be associated with certain disease processes, such as those related to schizophrenia, autism, and diabetes. Clinical studies show that certain probiotic strains, like Lactobacillus rhamnosus GG and Bifidobacterium animalis ssp. lactis help to prevent infection of pathogenic organisms (both bacterial and viral). This research may yield crucial contributions to disease prevention and public health. The dysbiosis may result in changes in the acquired immunity later on. The probiotic strains can prevent viral replication during SARS-CoV-2 or COVID-19 infection by reducing proinflammatory cytokines. There has been much interest into the intestinal flora as proposed by the diversity, volume, and proposed role in disease. Future research in the field of microbiome should be done in order to uncover their association to gut virome by noting both their influence on each other and relevant health and disease.

The role of microbiota-gut-brain axis in neurodegenerative diseases: biochemical and therapeutic aspects

“…The signaling pathway occurs through the conversion of the biosynthetic precursor 5-hydroxy-L-tryptophan (compound 2, Figure 1) into the neurotransmitter serotonin, whose secretion in CNS plays a fundamental role in the modulation of emotional control, appetite, sleep, sex, temperature, and pain processing [3,6,43]. Therefore, L-tryptophan metabolism products, such as serotonin, melatonin, and tryptamine (compound 6, Figure 1) have profound effects on the interaction between gut microbiota and neuroendocrine system, and gut immune responses [3,7,32]. However, evidence supports those changes in gut microbiota composition may have implications for modulating L-tryptophan metabolism in the axis-gut-brain interaction [6,32,43].…”

“…However, most of the known evidence suggests the involvement of vagal receptors that detect intestinal regulatory peptides, inflammatory molecules, dietary components, and bacterial metabolites to transmit signals to the CNS [3,17,33,47,53]. In this sense, it is possible to assume that the hormones and metabolites secreted by the microbiota and the intestinal EC influence CNS physiology [7,8,49]. Furthermore, dysregulation of the enzyme L-tryptophan hydroxylase, which is one of the central enzymes in the biosynthesis of serotonin, is a common disorder of psychiatric and gastrointestinal functions, such as anxiety and irritable bowel syndrome, suggesting the importance of this enzyme in the serotonin bioavailability [3,47,53].…”

“…The QUIN is responsible for metabolizing more than 95% of L-tryptophan in the GIT. QUIN allows the entry of L-tryptophan into the bloodstream and its passage through the BBB, and this mechanism is a critical factor for central serotonergic signaling [7,44,54,57]. Thus, the QUIN pathway is related to neurodegenerative processes due to its indispensable role in the biosynthesis of several important neuroactive intermediates, such as kynurenic acid, niacin, and the cofactor NAD + .…”

“…The most recent scientific advances have shown a close connection between the gastrointestinal tract (GIT), through the vagus nerve, with the central nervous system (CNS), contributing to the regulation of secretion, permeability, motility, and immunity of the digestive tract, exerting its effect on the enteric nervous system (ENS) [1,[4][5][6]. Due to this prominent role in the regulation and functionality of the CNS, the ENS has been considered a "second brain" since the structure of enteric neurons is a key factor in the control of the physiological response to the environment, muscle tissue, and the intestinal mucosa via the efferent autonomic nerve pathways [5,[7][8][9].…”

“…ENS influences brain functions through afferent signaling pathways and the secretion of biologically active substances in an intrinsic and bilateral relationship, providing a functional interaction and contributing to the coordination of the body's metabolic and homeostatic functions [4,6,7,10]. Thus, ENS has been suggested as an essential agent in the pathophysiology of chronic diseases, such as diabetes, metabolic syndromes, obesity, several autoimmune diseases, stress-induced psychosomatic disorders, schizophrenia, and some neurodegenerative diseases (NDs), as well as in the search for therapeutic targets and new drugs [7][8][9].…”