Background: Probiotics have a beneficial effect on inflammatory responses and immune regulation, via Janus kinase/signal transduction and activator of transcription (JAK/STAT) and NF‐κB signaling pathways. To evaluate the precise effects of Lactobacillus spp. as a protective and therapeutic agent, we aimed to investigate the efficacy of Lactobacillus spp. in modulating JAK/STAT and nuclear factor kappa B (NF‐κB) inflammatory signaling pathways.Methods: A quantitative real‐time polymerase chain reaction (qPCR) assay was used to analyze the expression of JAK/STAT and inflammatory genes (TIR‑associated Protein [TIRAP], Interleukin 1 Receptor Associated Kinase[IRAK4], Nuclear factor‐kappa B Essential Modulator [NEMO], and receptor interacting protein [RIP]) followed by treatment of the HT‐29 cell line with sonicated pathogens before, after, and simultaneously with Lactobacillus spp. A cytokine assay was also used to evaluate interleukin (IL)‐6 and IL‐1β production after treatment with Lactobacillus spp.Results: Lactobacillus spp. downregulated JAK and TIRAP, IRAK4, NEMO, and RIP genes in the NF‐κB pathway compared to sonicate‐treated cells. The expression of STAT genes was different after treatment with probiotics. The production of IL‐6 and IL‐1β decreased after probiotic treatment.Conclusions: Our Lactobacillus spp. cocktail showed anti‐inflammatory effects on HT‐29 cells by modulating JAK/STAT and NF‐κB signaling pathways in all three treatment variants. Therefore, Lactobacillus spp. as a dietary supplement can both prevent and reduce inflammation‐related diseases such as inflammatory bowel disease.

Background: Probiotics positively affect inflammatory responses, in part, through Janus kinase/signal transduction and activator of transcription (JAK/STAT) and inflammatory signaling pathways. To evaluate the precise effects of probiotics as protective treatment, we aimed to investigate the effectiveness of Lactobacillus spp., Bifidobacterium spp., and a mixture of these probiotics in modulating the JAK/STAT and inflammatory signaling pathways. Methods: A quantitative real-time polymerase chain reaction (qPCR) assay was used to analyze the expression of JAK/STAT and inflammatory genes (TIRAP, IRAK4, NEMO, and RIP) following HT-29 cell line treatment with sonicated pathogens Lactobacillus spp., Bifidobacterium spp., and a mixed cocktail. A cytokine assay was also used to evaluate the IL-6 and IL-1β production following the probiotic treatment. Results: The probiotic cocktail downregulated the JAK genes and TIRAP, IRAK4, NEMO, and RIP genes in the NF-kB pathway compared to sonicate pathogen treatment cells. The expression of STAT genes was variable following probiotic treatment. The IL-6 and IL-1β production decreased after probiotic treatment. Conclusions: Our probiotic cocktail showed anti-inflammatory effects on HT-29 cells by modulating JAK/STAT and NF-kB pathways. Therefore, Lactobacillus spp. and Bifidobacterium spp. probiotics as nutritional supplements may reduce inflammation-associated diseases such as inflammatory bowel disease (IBD).

Lactic acid bacteria (LAB) have been considered as potentially probiotic organisms due to their potential human health properties. This study aimed to evaluate both in vitro and in vivo, the potential probiotic properties of Lactobacillus species isolated from fecal samples of healthy humans in Iran. A total of 470 LAB were initially isolated from 53 healthy individual and characterized to species level. Of these, 88 (86%) were Lactobacillus species. Biochemical and genetic fingerprinting with Phene-Plate system (PhP-LB) and RAPD-PCR showed that the isolates were highly diverse consisted of 67(76.1%) and 75 (85.2%) single types (STs) and a diversity indices of 0.994 and 0.997, respectively. These strains were tested for production of adhesion to Caco-2 cells, antibacterial activity, production of B12, anti-proliferative effect and interleukin-8 induction on gut epithelial cell lines and antibiotic resistance against 9 commonly used antibiotics. Strains showing the characteristics consistent with probiotic strains, were further tested for their anti-inflammatory effect in mouse colitis model. Only one L. brevis; one L. rhamnosus and two L. plantarum were shown to have significant probiotic properties. These strains showed shortening the length of colon compared to dextran sulfate sodium and disease activity index (DAI) was also significantly reduced in mouse. Low number of LAB with potential probiotic activity as well as high diversity of lactobacilli species was evident in Iranian population. It also suggest that specific strains of L. plantarum, L. brevis and L. rhamnosus with anti-inflammatory effect in mouse model of colitis could be used as a potential probiotic candidate in inflammatory bowel disease to decrease the disease activity index.