LRRC19 Promotes Permeability of the Gut Epithelial Barrier Through Degrading PKC-ζ and PKCι/λ to Reduce Expression of ZO1, ZO3, and Occludin

A Review on Microengineering of Epithelial Barriers for Biomedical and Pharmaceutical Research

Epithelial tissue forms a barrier around the human body and visceral organs, providing protection, permeation, sensation, and secretion. It is vital for our sustenance as it protects the tissue from harm and injury by restricting the entry of foreign bodies inside. Furthermore, it is a strong barrier to drugs, nutrients, and other essential deliverables. This layer also houses a large consortium of microbes, which thrive in tandem with human tissue, providing several health benefits. Moreover, the complex interplay of the microbiome with the barrier tissue is poorly understood. Therefore, replicating these barrier tissues on microdevices to generate physiological and pathophysiological models has been a huge interest for researchers over the last few decades. The artificially engineered reconstruction of these epithelial cellular barriers on microdevices could help underpin the host-microbe interaction, generating a physiological understanding of the tissue, tissue remodeling, receptor-based selective diffusion, drug testing, and others. In addition, these devices could reduce the burden of animal sacrifices for similar research and minimize the failure rate in drug discovery due to the use of primary human cells and others. This review discusses the nature of the epithelial barrier at different tissue sites, the recent developments in creating engineered barrier models, and their applications in pathophysiology, host-microbe interactions, drug discovery, and cytotoxicity. The review aims to provide know-how and knowledge behind engineered epithelial barrier tissue to bioengineers, biotechnologists, and scientists in allied fields.

Jianpi-Huatan-Huoxue-Anshen formula ameliorates gastrointestinal inflammation and microecological imbalance in chemotherapy-treated mice transplanted with H22 hepatocellular carcinoma

BACKGROUND

Jianpi-Huatan-Huoxue-Anshen formula [Tzu-Chi cancer-antagonizing & life-protecting II decoction (TCCL)] is a Chinese medical formula that has been clinically shown to reduce the gastrointestinal side effects of chemotherapy in cancer patients and improve their quality of life. However, its effect and mechanism on the intestinal microecology after chemotherapy are not yet clear.

AIM

To discover the potential mechanisms of TCCL on gastrointestinal inflammation and microecological imbalance in chemotherapy-treated mice transplanted with hepatocellular carcinoma (HCC).

METHODS

Ninety-six mice were inoculated subcutaneously with HCC cells. One week later, the mice received a large dose of 5-fluorouracil by intraperitoneal injection to establish a HCC chemotherapy model. Thirty-six mice were randomly selected before administration, and feces, ileal tissue, and ileal contents were collected from each mouse. The remaining mice were randomized into normal saline, continuous chemotherapy, Yangzheng Xiaoji capsules-treated, and three TCCL-treated groups. After treatment, feces, tumors, liver, spleen, thymus, stomach, jejunum, ileum, and colon tissues, and ileal contents were collected. Morphological changes, serum levels of IL-1β, IL-6, IL-8, IL-10, IL-22, TNF-α, and TGF-β, intestinal SIgA, and protein and mRNA expression of ZO-1, NF-κB, Occludin, MUC-2, Claudin-1, and IκB-α in colon tissues were documented. The effect of TCCL on the abundance and diversity of intestinal flora was analyzed using 16S rDNA sequencing.

RESULTS

TCCL treatment improved thymus and spleen weight, thymus and spleen indexes, and body weight, decreased tumor volumes and tumor tissue cell density, and alleviated injury to gastric, ileal, and colonic mucosal tissues. Among proteins and genes associated with inflammation, IL-10, TGF-β, SIgA, ZO-1, MUC-2, and Occludin were upregulated, whereas NF-κB, IL-1β, IL-6, TNF-α, IL-22, IL-8, and IκB-α were downregulated. Additionally, TCCL increased the proportions of fecal Actinobacteria, AF12, Adlercreutzia, Clostridium, Coriobacteriaceae, and Paraprevotella in the intermediate stage of treatment, decreased the proportions of Mucipirillum, Odoribacter, RF32, YS2, and Rikenellaceae but increased the proportions of p_Deferribacteres and Lactobacillus at the end of treatment. Studies on ileal mucosal microbiota showed similar findings. Moreover, TCCL improved community richness, evenness, and the diversity of fecal and ileal mucosal flora.

CONCLUSION

TCCL relieves pathological changes in tumor tissue and chemotherapy-induced gastrointestinal injury, potentially by reducing the release of pro-inflammatory factors to repair the gastrointestinal mucosa, enhancing intestinal barrier function, and maintaining gastrointestinal microecological balance. Hence, TCCL is a very effective adjuvant to chemotherapy.

Dietary nobiletin regulated cefuroxime- and levofloxacin-associated "gut microbiota-metabolism" imbalance and intestinal barrier dysfunction in mice

Nobiletin (NOB) exhibits significant biological activities and may be a potential dietary treatment for antibiotic-associated gut dysbiosis. In this study, mice were gavaged with 0.2 mL day-1 of 12.5 g L-1 cefuroxime (LFX) and 10 g L-1 levofloxacin (LVX) for a duration of 10 days, accompanied by 0.05% NOB to investigate the regulatory effect and potential mechanisms of NOB on antibiotic-induced intestinal microbiota disorder and intestinal barrier dysfunction. Our results indicated that dietary NOB improved the pathology of intestinal epithelial cells and the intestinal permeability by upregulating the expression of intestinal tight junction proteins (TJs) and the number of goblet cells. Furthermore, dietary NOB reduced the levels of serum lipopolysaccharide (LPS) and pro-inflammatory factors (TNF-α and IL-1β), thereby facilitating the restoration of the intestinal mucosal barrier. Additionally, dietary NOB increased the abundance of beneficial bacteria f_Lachnospiraceae and regulated the metabolic disorders of short-chain fatty acids (SCFAs) and bile acids (BAs). Notably, NOB supplementation resulted in elevated levels of butyric acid and lithocholic acid (LCA), which contributed to the repair of the intestinal mucosal barrier function and the maintenance of intestinal homeostasis. Collectively, our results propose a healthy dietary strategy for the prevention or mitigation of antibiotic-associated gut dysbiosis by dietary NOB.

Desulfovibrio vulgaris interacts with novel gut epithelial immune receptor LRRC19 and exacerbates colitis

BACKGROUND

The overgrowth of Desulfovibrio, an inflammation promoting flagellated bacteria, has been found in ulcerative colitis (UC) patients. However, the molecular mechanism in promoting colitis remains unestablished.

METHODS

The relative abundance Desulfovibrio vulgaris (D. vulgaris) in stool samples of UC patients was detected. Mice were treated with dextran sulfate sodium to induce colitis with or without administration of D. vulgaris or D. vulgaris flagellin (DVF), and the severity of colitis and the leucine-rich repeat containing 19 (LRRC19) signaling were assessed. The interaction between DVF and LRRC19 was identified by surface plasmon resonance and intestinal organoid culture. Lrrc19-/- and Tlr5-/- mice were used to investigate the indispensable role of LRRC19. Finally, the blockade of DVF-LRRC19 interaction was selected through virtual screening and the efficacy in colitis was assessed.

RESULTS

D. vulgaris was enriched in fecal samples of UC patients and was correlated with the disease severity. D. vulgaris or DVF treatment significantly exacerbated colitis in germ-free mice and conventional mice. Mechanistically, DVF could interact with LRRC19 (rather than TLR5) in colitis mice and organoids, and then induce the production of pro-inflammatory cytokines. Lrrc19 knockdown blunted the severity of colitis. Furthermore, typhaneoside, a blockade of binding interfaces, blocked DVF-LRRC19 interaction and dramatically ameliorated DVF-induced colitis.

CONCLUSIONS

D. vulgaris could promote colitis through DVF-LRRC19 interaction. Targeting DVF-LRRC19 interaction might be a new therapeutic strategy for UC therapy. Video Abstract.

Dietary 5-demethylnobiletin prevents antibiotic-associated dysbiosis of gut microbiota and damage to the colonic barrier

5-Demethylnobiletin (5DN) is an important ingredient of citrus extract that is rich in polymethoxyflavones (PMFs). In this study, we systemically investigated the preventive effects of 5DN on antibiotic-associated intestinal disturbances. Experimental mice were gavaged 0.2 mL per day of the antibiotic cocktail (12.5 g L^-1 cefuroxime and 10 g L^-1 levofloxacin) for 10 days, accompanied by dietary 0.05% 5DN for 10 and 20 days. The results showed that the combination of cefuroxime and levofloxacin caused swelling of the cecum and injury to the colon tissue. Meanwhile, the balance of intestinal oxidative stress and the barrier function of mice was also damaged by the antibiotics through upregulation of the relative mRNA levels of superoxide dismutase 3 (SOD3), quinine oxidoreductase 1 (NQO1) and glutathione peroxidase 1 (GPX1), and downregulation of the relative protein levels of tight junction proteins (TJs). Moreover, antibiotic exposure led to disorder of the gut microbiota, particularly increased harmful bacteria (Proteobacteria) and decreased beneficial bacteria (Bacteroideta). However, dietary 5DN could reduce antibiotic-associated intestinal damage, evidenced by the results that 5DN alleviated gut oxidative damage and attenuated intestinal barrier injury via increasing the expression of TJs including occludin and zonula occluden1 (ZO1). Additionally, dietary 5DN modulated the composition of the gut microbiota in antibiotic-treated mice by increasing the relative levels of beneficial bacteria, such as Dubosiella and Lactobacillus. Moreover, PMFs increased the contents of isobutyric acid and butyric acid, which were almost eliminated by antibiotic exposure. In conclusion, 5DN could alleviate antibiotic-related imbalance of intestinal oxidative stress, barrier function damage, intestinal flora disorders and the reduction of short-chain fatty acids (SCFAs), which lays a foundation for exploring safer and more effective ways to prevent or mitigate antibiotic-associated intestinal damage.

Dietary fish oil improves autistic behaviors and gut homeostasis by altering the gut microbial composition in a mouse model of fragile X syndrome

Fragile X syndrome (FXS) is the most common inherited intellectual disability, caused by a lack of the fragile X mental retardation protein (FMRP). Individuals with neurodevelopmental disorders frequently experience gastrointestinal problems that are primarily linked to gut microbial dysbiosis, inflammation, and increased intestinal permeability. Omega-3 polyunsaturated fatty acids (omega-3 PUFAs) are non-pharmacological agents that exert potential therapeutic effects against neurological disorders. However, it is unclear whether omega-3 PUFAs improve autistic behaviors in fragile X syndrome (FXS) by altering the gut microbial composition. Here, we describe gastrointestinal problems in Fmr1 knockout (KO) mice. FMRP deficiency causes intestinal homeostasis dysfunction in mice. Fish oil (FO) as a source of omega-3 PUFAs reduces intestinal inflammation but increases the mRNA and protein levels of TJP3 in the colon of juvenile Fmr1 KO mice. Fecal microbiota transplantation from FO-fed Fmr1 KO mice increased the gut abundance of Akkermansia and Gordonibacter in recipient Fmr1 KO mice and improved gut homeostasis and autistic behaviors. Our findings demonstrate that omega-3 PUFAs improve autistic behaviors and gut homeostasis in FMRP-deficient mice by suppressing gut microbiota dysbiosis, thereby presenting a novel therapeutic approach for juvenile FXS treatment.

Downregulation of LRRC19 Is Associated with Poor Prognosis in Colorectal Cancer

OBJECTIVE

Colorectal cancer (CRC) is globally one of the most often diagnosed cancers with high mortality rates. This study aimed to explore novel biomarkers for the diagnosis and prognosis of CRC.

METHODS

We collected 4 datasets about CRC in GEO and sought differentially expressed genes (DEGs) with GEO2R. Leucine-rich repeat-containing protein 19 (LRRC19) expression was assessed through the Oncomine and TIMER database analyses, which was further confirmed by qRT-PCR of CRC samples. We used online survival analysis tools (GEPIA, PrognoScan, and Kaplan-Meier plotter) to examine the prognostic value of LRRC19 in CRC and other malignancies. GO and KEGG enrichment analyses were employed to explore the biological functions of LRRC19. Finally, we conducted network prediction by STRING and further validation on the GEPIA to discover other molecules that might interact with LRRC19.

RESULTS

A total of 21 upregulated and 46 downregulated DEGs were identified from the 4 datasets. The TIMER and Oncomine online analyses showed lower mRNA of LRRC19 in CRC tissues compared with adjacent normal tissues, which was validated by qRT-PCR in CRC patient samples. The survival analysis through the GEPIA and PrognoScan websites revealed that low LRRC19 expression was significantly correlated with poor prognosis in CRC patients. The Kaplan-Meier plotter survival analysis indicated that low LRRC19 expression was significantly associated with the disease progression of patients with ovarian cancer, gastric cancer, breast cancer, and lung cancer. The enrichment analysis suggested that low expression of LRRC19 could be involved in the retinol metabolism and the zymogen granule membrane. Through STRING and GEPIA, it was found that LRRC19 is clearly associated with ZCCHC10, MOB3B, IMMP2L, and TRMT11.

CONCLUSION

LRRC19 mRNA was prominently decreased in human CRC tissues and was significantly associated with shorter survival in CRC patients. LRRC19 might serve as a possible target for early diagnosis and prognosis assessment in CRC.