The transcription factor HLH-26 controls probiotic-mediated protection against intestinal infection through up-regulation of the Wnt/BAR-1 pathway

Probiotics-sensing mechanism in neurons that initiates gut mitochondrial surveillance for pathogen defense

Animals constantly face microbial challenges, and microbe-mediated infection protection is crucial for host survival. Identifying specific bacteria and their interactions with host intracellular surveillance systems is important but challenging. Here, we develop a "probiotics" screening system that identifies Escherichia coli mutants, such as ΔymcB, which protect hosts from Pseudomonas aeruginosa PA14 infection by activating the mitochondrial unfolded protein response (UPRmt). Genetic screening reveals that MDSS-1, a neuronal transmembrane protein, is crucial for sensing ΔymcB and triggering intestinal UPRmt. MDSS-1 functions as a potential receptor in ASE neurons, detecting ΔymcB and transmitting signals through neuropeptides, GPCRs, Wnt signaling, and endopeptidase inhibitors to activate intestinal UPRmt and enhance protection. Constitutive activation of MDSS-1 in ASE neurons is sufficient to induce UPRmt and confer infection resistance. This study uncovers a neuron-intestine communication mechanism, where ASE neurons detect bacteria and modulate the intestinal mitochondrial surveillance system for host adaptation to pathogens.

Kombucha Tea-associated microbes remodel host metabolic pathways to suppress lipid accumulation

The popularity of the ancient, probiotic-rich beverage Kombucha Tea (KT) has surged in part due to its purported health benefits, which include protection against metabolic diseases; however, these claims have not been rigorously tested and the mechanisms underlying host response to the probiotics in KT are unknown. Here, we establish a reproducible method to maintain C. elegans on a diet exclusively consisting of Kombucha Tea-associated microbes (KTM), which mirrors the microbial community found in the fermenting culture. KT microbes robustly colonize the gut of KTM-fed animals and confer normal development and fecundity. Intriguingly, animals consuming KTMs display a marked reduction in total lipid stores and lipid droplet size. We find that the reduced fat accumulation phenotype is not due to impaired nutrient absorption, but rather it is sustained by a programed metabolic response in the intestine of the host. KTM consumption triggers widespread transcriptional changes within core lipid metabolism pathways, including upregulation of a suite of lysosomal lipase genes that are induced during lipophagy. The elevated lysosomal lipase activity, coupled with a decrease in lipid droplet biogenesis, is partially required for the reduction in host lipid content. We propose that KTM consumption stimulates a fasting-like response in the C. elegans intestine by rewiring transcriptional programs to promote lipid utilization. Our results provide mechanistic insight into how the probiotics in Kombucha Tea reshape host metabolism and how this popular beverage may impact human metabolism.

Geroprotective potential of microbiome modulators in the Caenorhabditis elegans model

Aging is associated with cellular and physiological changes, which significantly reduce the quality of life and increase the risk for disease. Geroprotectors improve lifespan and slow the progression of detrimental aging-related changes such as immune system senescence, mitochondrial dysfunction, and dysregulated nutrient sensing and metabolism. Emerging evidence suggests that gut microbiota dysbiosis is a hallmark of aging-related diseases and microbiome modulators, such as probiotics (live bacteria) or postbiotics (non-viable bacteria/bacterial byproducts) may be promising geroprotectors. However, because they are strain-specific, the geroprotective effects of probiotics and postbiotics remain poorly understood and understudied. Drosophila melanogaster, Caenorhabditis elegans, and rodents are well-validated preclinical models for studying lifespan and the role of probiotics and/or postbiotics, but each have their limitations, including cost and their translation to human aging biology. C. elegans is an excellent model for large-scale screening to determine the geroprotective potential of drugs or probiotics/postbiotics due to its short lifecycle, easy maintenance, low cost, and homology to humans. The purpose of this article is to review the geroprotective effects of microbiome modulators and their future scope, using C. elegans as a model. The proposed geroprotective mechanisms of these probiotics and postbiotics include delaying immune system senescence, preventing or reducing mitochondrial dysfunction, and regulating food intake (dietary restriction) and metabolism. More studies are warranted to understand the geroprotective potential of probiotics and postbiotics, as well as other microbiome modulators, like prebiotics and fermented foods, and use them to develop effective therapeutics to extend lifespan and reduce the risk of debilitating aging-related diseases.

The effects of Lactobacillus delbrueckii and Lactobacillus rhamnosus on cytokines and their related molecules: An ex vivo study on patients with systemic lupus erythematosus

Objectives

This study aimed to assess the ex vivo impact of Lactobacillus delbrueckii (L. delbrueckii) and Lactobacillus rhamnosus (L. rhamnosus) on inflammatory and anti-inflammatory cytokines as well as their related molecules on the peripheral blood mononuclear cells (PBMCs) of systemic lupus erythematosus (SLE) patients.

Patients and methods

This study was conducted with 20 newly diagnosed SLE patients (18 females, 2 males; mean age: 33.3±12.4 years; range, 18 to 68 years) between September 2017 and September 2018. Extracted PBMCs from each patient were divided into 4 cell groups in our study. Three cell groups act as treatment groups receiving L. rhamnosus (107 CFU/mL), L. delbrueckii (105 CFU/mL) or a mixture of both, and one group act as our untreated control group in the absence of any probiotic agents. All cell groups were cultured in RPMI 1460 medium for 48 h. Then, total RNA was extracted, and cDNA was synthesized.

Results

The gene expression levels of forkhead box P3 (FOXP3), transforming growth factor beta (TGF-β), interleukin (IL)-6, IL-10, and IL-2 were evaluated by a quantitative real-time polymerase chain reaction. The results revealed that expression levels of FOXP3, TGF-β, IL-10, and IL-2 increased and the level of IL-6 decreased in probiotics-receiving groups compared to the control group. Lactobacillus delbrueckii and L. rhamnosus enhanced the expression of regulatory T cell-related molecules such as FOXP3 and IL-2 and also increased the expression of IL-10. These probiotics also reduced the expression of IL-6 as proinflammatory cytokines in the PBMCs of SLE patients.

Conclusion

The results of the present study show that these probiotics could be effective in regulating the balance of cytokine gene expression ex vivo , and due to their beneficial effects, they can be an intriguing option in the production of new complement drugs for SLE.

The homeodomain transcription factor CEH-37 regulates PMK-1/p38 MAPK pathway to protect against intestinal infection via the phosphatase VHP-1

Increasing evidence indicate that the expression of defense genes at the right place and the right time are regulated by host-defense transcription factors. However, the precise mechanisms of this regulation are not well understood. Homeodomain transcription factors, encoded by homeobox genes, play crucial role for the development of multicellular eukaryotes. In this study, we demonstrated that homeodomain transcription factor CEH-37 (known as OTX2 in mammals) was a key transcription factor for host defense in Caenorhabditis elegans. Meanwhile, CEH-37 acted in the intestine to protect C. elegans against pathogen infection. We further showed that the homeodomain transcription factor CEH-37 positively regulated PMK-1/ p38 MAPK activity to promote the intestinal immunity via suppression phosphatase VHP-1. Furthermore, we demonstrated that this function was conserved, because the human homeodomain transcription factor OTX2 also exhibited protective function in lung epithelial cells during Pseudomonas aeruginosa infection. Thus, our work reveal that CEH-37/OTX2 is a evolutionarily conserved transcription factor for defense against pathogen infection. The finding provides a model in which CEH-37 decreases VHP-1 phosphatase activity, allowing increased stimulation of PMK-1/p38 MAPK phosphorylation cascade in the intestine for pathogen resistance.

Paeoniflorin increases the survival of Pseudomonas aeruginosa infected Caenorhabditis elegans at the immunosuppression stage by activating PMK-1, BAR-1, and EGL-1 signals

Paeoniflorin is the major active compound of total glycoside of paeony in Paeonia lactiflora Pall. Although several aspects of beneficial effects of paeoniflorin have been described, whether the paeoniflorin treatment is helpful for inhibiting the pathogen infection-induced immunosuppression remains largely unclear. Using the immunosuppression model in Caenorhabditis elegans induced by Pseudomonas aeruginosa infection, we here examined the beneficial effect of paeoniflorin treatment against the immunosuppression induced by bacterial pathogen infection. In this immunosuppression model, we observed that the survival rate of P. aeruginosa infected nematodes at the immunosuppression stage could be significantly increased by 25-100 mg/L paeoniflorin treatment. P. aeruginosa accumulation in intestinal lumen of nematodes at the immunosuppression stage was reduced by paeoniflorin treatment. Paeoniflorin could activate the expressions of antimicrobial genes (lys-1 and lys-8) in nematodes at the immunosuppression stage. Moreover, at the immunosuppression stage, paeoniflorin treatment increased the expressions of bar-1, pmk-1, and egl-1 required for the control of innate immunity against bacterial infection. Meanwhile, RNAi of bar-1, pmk-1, and egl-1 inhibited the beneficial effect of paeoniflorin treatment in increasing the survival, reducing the P. aeruginosa accumulation in intestinal lumen, and activating the expressions of antimicrobial genes (lys-1 and lys-8) in nematodes at the immunosuppression stage. Therefore, paeoniflorin treatment could effectively inhibit the immunosuppression induced by bacterial pathogen infection in the hosts.