Heat-killed probiotic Levilactobacillus brevis MKAK9 and its exopolysaccharide promote longevity by modulating aging hallmarks and enhancing immune responses in Caenorhabditis elegans.

BACKGROUND: Proteostasis is a critical aging hallmark responsible for removing damaged or misfolded proteins and their aggregates by improving proteasomal degradation through the autophagy-lysosome pathway (ALP) and the ubiquitin-proteasome system (UPS). Research on the impact of heat-killed probiotic bacteria and their structural components on aging hallmarks and innate immune responses is scarce, yet enhancing these effects could potentially delay age-related diseases. RESULTS: This study introduces a novel heat-killed Levilactobacillus brevis strain MKAK9 (HK MKAK9), along with its exopolysaccharide (EPS), demonstrating their ability to extend longevity by improving proteostasis and immune responses in wild-type Caenorhabditis elegans. We elucidate the underlying mechanisms through a comprehensive approach involving mRNA- and small RNA sequencing, proteomic analysis, lifespan assays on loss-of-function mutants, and quantitative RT-PCR. Mechanistically, HK MKAK9 and its EPS resulted in downregulation of the insulin-like signaling pathway in a DAF-16-dependent manner, enhancing protein ubiquitination and subsequent proteasomal degradation through activation of the ALP pathway, which is partially mediated by microRNA mir-243. Importantly, autophagosomes engulf ubiquitinylated proteins, as evidenced by increased expression of the autophagy receptor sqst-3, and subsequently fuse with lysosomes, facilitated by increased levels of the lysosome-associated membrane protein (LAMP) lmp-1, suggesting the formation of autolysosomes for degradation of the selected cargo. Moreover, HK MKAK9 and its EPS activated the p38 MAPK pathway and its downstream SKN-1 transcription factor, which are known to regulate genes involved in innate immune response (thn-1, ilys-1, cnc-2, spp-9, spp-21, clec-47, and clec-266) and antioxidation (sod-3 and gst-44), thereby reducing the accumulation of reactive oxygen species (ROS) at both cellular and mitochondrial levels. Notably, SOD-3 emerged as a transcriptional target of both DAF-16 and SKN-1 transcription factors. CONCLUSION: Our research sets a benchmark for future investigations by demonstrating that heat-killed probiotic and its specific cellular component, EPS, can downregulate the insulin-signaling pathway, potentially improving the autophagy-lysosome pathway (ALP) for degrading ubiquitinylated proteins and promoting organismal longevity. Additionally, we discovered that increased expression of microRNA mir-243 regulates insulin-like signaling and its downstream ALP pathway. Our findings also indicate that postbiotic treatment may bolster antioxidative and innate immune responses, offering a promising avenue for interventions in aging-related diseases.

HSA over BSA: Selective detection of Human Serum Albumin via a naphtho [2,1-b] furan-based system.

Human serum albumin (HSA) is an important biomarker that can be used for the early diagnosis of many diseases. In this work, a TICT probe bearing fused naphtho-furan scaffold (NPNF) was developed and employed in the selective turn-on sensing of HSA. The probe's selectivity towards HSA was observed using steady-state fluorescence experiments, with limit of quantitation in micromolar levels. NPNF's capability to exclusively detect HSA over BSA was further studied/rationalized using anisotropy and time-resolved studies. Molecular docking was used to shed light on the location of NPNF in the subdomain IB of HSA. The practical application of the probe was also demonstrated by the detection of HSA in urine and the HSA-assisted detection of cerium.

Probiotic and anti-inflammatory properties of Lactiplantibacillus plantarum MKTJ24 isolated from an artisanal fermented fish of North-east India.

The study aimed to isolate and characterize lactic acid bacteria from various traditional fermented fish products from North East India, including Xindol, Hentak, and Ngari, which hold significant dietary importance for the indigenous tribes. Additionally, the study sought to examine their untargeted metabolomic profiles. A total of 43 strains of Bacillus, Priestia, Staphylococcus, Pediococcus, and Lactiplantibacillus were isolated, characterized by 16 S rRNA gene and tested for probiotic properties. Five strains passed pH and bile salt tests with strain dependent antimicrobial activity, which exhibited moderate autoaggregation and hydrophobicity properties. Lactiplantibacillus plantarum MKTJ24 exhibited the highest hydrophobicity (42 %), which was further confirmed by adhesion assay in HT-29 cell lines (100 %). Lactiplantibacillus plantarum MKTJ24 treatment in LPS-stimulated HT-29 cells up-regulated expression of mucin genes compared to LPS-treated cells. Treatment of RAW 264.7 cells with Lactiplantibacillus plantarum MKTJ24 decreased LPS-induced reactive oxygen species (ROS) and nitric oxide (NO) productions. Further, genome analysis of Lactiplantibacillus plantarum MKTJ24 revealed the presence of several probiotic markers and immunomodulatory genes. The genome was found to harbor plantaricin operon involved in bacteriocin production. A pangenome analysis using all the publicly available L. plantarum genomes specifically isolated from fermented fish products identified 120 unique genes in Lactiplantibacillus plantarum MKTJ24. Metabolomic analysis indicated dominance of ascorbic acids, pentafluropropionate, cyclopropaneacetic acid, florobenzylamine, and furanone in Xindol. This study suggests that Lactiplantibacillus plantarum MKTJ24 has potential probiotic and immunomodulatory properties that could be used in processing traditional fermented fish products on an industrial scale to improve their quality and enhance functional properties.