Potential probiotics for regulation of the gut-lung axis to prevent or alleviate influenza in vulnerable populations.

Influenza, also known as "flu", is an infectious disease caused by influenza viruses. Three types of influenza virus, A, B, and C, are able to infect humans. In most people, influenza causes mild symptoms, but it can also induce severe complications and death. Annual influenza vaccines are currently the main intervention used to minimize mortality and morbidity. However, vaccination frequently fails to provide adequate protection, especially in the elderly. Traditional flu vaccine targets hemagglutinin to prevent virus infection, but the constant mutation of hemagglutinin means that it is a challenge to develop vaccines quickly enough to keep up with mutations. Thus, other methods of curbing influenza incidence would be welcomed, especially for vulnerable populations. Although influenza viruses primarily infect the respiratory tract, influenza virus infection also induces intestinal dysbiosis. Through gut microbiota-derived secreted products and the circulating immune cells, gut microbiota can affect pulmonary immunity. The crosstalk between the respiratory tract and gut microbiota, termed the "gut-lung axis", is observed in the regulation of immune responses against influenza virus infection or inflammation-induced lung damage, indicating the possibility of using probiotics to prevent influenza virus infection or alleviate respiratory symptoms. In this review, we summarize the current findings on the antiviral functions of particular probiotics and/or combinations and discuss the antiviral mechanisms and immunomodulatory activities of probiotics in vitro, in mice, and in humans. Clinical studies show probiotic supplements can provide health benefits, not only to the elderly or children with compromised immune systems, but also to young- and middle-aged adults.

Screening of Lactic Acid Bacterial Strains with Antiviral Activity Against Porcine Epidemic Diarrhea.

Newly emerging and re-emerging viral infectious diseases cause significant economic losses in swine production. Efficacious vaccines have not yet been developed for several major swine infectious diseases, including porcine epidemic diarrhea virus (PEDV). We used the PEDV-infected Vero cell model to screen lactic acid bacteria (LAB) strains with antiviral activity. Sixty LAB strains were isolated from the feces of nursing piglets. After the elimination of LAB strains with high cytotoxicity to Vero cells, the protective effects of the remaining 6 strains against PEDV infection were determined. Vero cells pretreated with the intracellular extracts or cell wall fractions of YM22 and YM33 strains for 24 h before infection with PEDV showed significantly higher cell viabilities and lower mRNA expression of PEDV nucleocapsid (PEDV-N) than the unpretreated cells, indicating that the intracellular extracts and cell wall fractions of YM22 and YM33 possessed prophylactic effects on Vero cells against PEDV infection. PEDV-infection significantly increased the mRNA expression of proinflammatory cytokines, including tumor necrosis factor-α (TNF-α) and interleukin-8 (IL-8) in Vero cells. However, pretreatment of Vero cells with the cell wall fractions of YM22 and YM33 decreased the mRNA expression of TNF-α and IL-8, which could be a mechanism associated with the protective effects of YM22 and YM33 against PEDV. Based on the biochemical characteristics and phylogenetic analyses, YM22 and YM33 were identified as Ligilactobacillus agilis (basonym: Lactobacillus agilis) and Ligilactobacillus salivarius (basonym: Lactobacillus salivarius), respectively. These findings suggest that L. agilis YM22 and L. salivarius YM33 could provide some levels of protective effects against PEDV infections.

Protective and Detoxifying Effects Conferred by Dietary Selenium and Curcumin against AFB1-Mediated Toxicity in Livestock: A Review.

Aflatoxin B1 (AFB1), among other aflatoxins of the aflatoxin family, is the most carcinogenic and hazardous mycotoxin to animals and human beings with very high potency leading to aflatoxicosis. Selenium is an essential trace mineral possessing powerful antioxidant functions. Selenium is widely reported as an effective antioxidant against aflatoxicosis. By preventing oxidative liver damage, suppressing pro-apoptotic proteins and improving immune status in AFB1 affected animals; selenium confers specific protection against AFB1 toxicity. Meticulous supplementation of animal feed by elemental selenium in the organic and inorganic forms has proven to be effective to ameliorate AFB1 toxicity. Curcumin is another dietary agent of importance in tackling aflatoxicosis. Curcumin is one of the major active ingredients in the tubers of a spice Curcuma longa L., a widely reported antioxidant, anticarcinogenic agent with reported protective potential against aflatoxin-mediated liver damage. Curcumin restricts the aflatoxigenic potential of Aspergillusflavus. Curcumin inhibits cytochrome P450 isoenzymes, particularly CYP2A6 isoform; thereby reducing the formation of AFB1-8, 9-epoxide and other toxic metabolites causing aflatoxicosis. In this review, we have briefly reviewed important aflatoxicosis symptoms among animals. With the main focus on curcumin and selenium, we have reviewed their underlying protective mechanisms in different animals along with their extraction and production methods for feed applications.