Microbiota and Its Role on Viral Evasion: Is It With Us or Against Us?

Viruses are obligate intracellular pathogens that require the protein synthesis machinery of the host cells to replicate. These microorganisms have evolved mechanisms to avoid detection from the host immune innate and adaptive response, which are known as viral evasion mechanisms. Viruses enter the host through skin and mucosal surfaces that happen to be colonized by communities of thousands of microorganisms collectively known as the commensal microbiota, where bacteria have a role in the modulation of the immune system and maintaining homeostasis. These bacteria are necessary for the development of the immune system and to prevent the adhesion and colonization of bacterial pathogens and parasites. However, the interactions between the commensal microbiota and viruses are not clear. The microbiota could confer protection against viral infection by priming the immune response to avoid infection, with some bacterial species being required to increase the antiviral response. On the other hand, it could also help to promote viral evasion of certain viruses by direct and indirect mechanisms, with the presence of the microbiota increasing infection and viruses using LPS and surface polysaccharides from bacteria to trigger immunosuppressive pathways. In this work, we reviewed the interaction between the microbiota and viruses to prevent their entry into host cells or to help them to evade the host antiviral immunity. This review is focused on the influence of the commensal microbiota in the viruses' success or failure of the host cells infection.

Probiotics: Protecting Our Health from the Gut

The gut microbiota (GM) comprises billions of microorganisms in the human gastrointestinal tract. This microbial community exerts numerous physiological functions. Prominent among these functions is the effect on host immunity through the uptake of nutrients that strengthen intestinal cells and cells involved in the immune response. The physiological functions of the GM are not limited to the gut, but bidirectional interactions between the gut microbiota and various extraintestinal organs have been identified. These interactions have been termed interorganic axes by several authors, among which the gut-brain, gut-skin, gut-lung, gut-heart, and gut-metabolism axes stand out. It has been shown that an organism is healthy or in homeostasis when the GM is in balance. However, altered GM or dysbiosis represents a critical factor in the pathogenesis of many local and systemic diseases. Therefore, probiotics intervene in this context, which, according to various published studies, allows balance to be maintained in the GM, leading to an individual's good health.

Recombinant p40 Protein Promotes Expression of Occludin in HaCaT Keratinocytes: A Brief Communication

The ability of epithelial barriers to perform as the first defense line against external damage derives from tight junctions, protein complexes that block microorganisms through the paracellular space. Indeed, disturbances of barrier permeability caused by bacterial metabolites and other inflammatory stimuli are the consequence of changes in protein expression in these complexes. Postbiotics, molecules derived from bacteria with beneficial effects on the host, improve barrier function through the activation of survival pathways in epithelial cells. Lacticaseibacillus rhamnosus GG secretes the muramidase p40, which protects intestinal barriers through an EGFR-dependent pathway. In this work, we cloned, expressed, and purified the recombinant p40 protein from L. rhamnosus GR-1 to evaluate its effect on cell viability, cell cytotoxicity, TEER, and protein levels of tight junctions, as well as EGFR activation via Western blot on HaCaT keratinocytes subjected to LPS. We found a novel mutation at residue 368 that does not change the structure of p40. Our protein also reduces the LPS-induced increase in cell cytotoxicity when it is added prior to this stimulus. Furthermore, although LPS did not cause changes in barrier function, p40 increased TEER and occludin expression in HaCaT, but unlike previous work with p40 from LGG, we found that recombinant p40 did not activate EGFR. This suggests that recombinant p40 enhances epithelial barrier function through distinct signaling pathways.

[Cytokines and nervous system: relationship with schizophrenia]

Schizophrenia is a heterogeneous disorder of mental symptoms and alterations, characterized by presenting abnormal ideas and perceptions, in which the individual loses contact with reality as a result of a complex neuropsychological disorganization, which affects the affective, intellectual and behavioral functioning; as well as inducing a significant social dysfunction. The etiology of schizophrenia is extremely complex, and is not very clear yet; it is believed to be the result of the combination of genetic factors and the environment. Numerous neurotransmitters have been implicated in this disease, as is the case of dopamine, serotonin and glutamate. The role of the inflammatory process in the pathogenesis of schizophrenia has been postulated, where a prenatal immune "challenge" during the second trimester of pregnancy can be key to the development of the disease. Some of the pro-inflammatory cytokines (TNF-alpha, IL-1beta and IL-6) play a key role in the processes of modulation of the nervous system functions related to affective, emotional and social alterations in subjects with schizophrenia. The mechanisms associated with inflammation and the anti-inflammatory defense system that may be associated with the development of schizophrenia are still unknown. This review was intended to address schizophrenia, in regards to the mechanisms associated with inflammation and the anti-inflammatory defense system in its development.