Cholangiocarcinoma (CCA) is a particularly aggressive and challenging type of cancer, known for its poor prognosis, which is worsened by the complex interplay of various biological and environmental factors that contribute to its development. Recently, researchers have increasingly focused on the significant role of the biliary-enteric communication of liver-gut axis in the pathogenesis of CCA, highlighting a complex relationship that has not been thoroughly explored before. This review aims to summarize the key concepts related to the biliary-enteric communication of liver-gut axis and investigate its potential mechanisms that may lead to the onset and progression of CCA, a disease that presents substantial treatment challenges. Important areas of focus will include the microbiome's profound influence, which interacts with host physiology in ways that may worsen cancer development; changes in bile acid metabolism that can create toxic environments favorable for tumor growth; the regulation of inflammatory processes that may either promote or inhibit tumor progression; the immune system's involvement, which is crucial in the body's response to cancer; and the complex interactions within metabolic pathways that can affect cellular behavior and tumor dynamics. By integrating recent research findings from various studies, we aim to explore the multifaceted roles of the biliary-enteric communication of liver-gut axis in CCA, providing new insights and perspectives for future research while identifying promising therapeutic targets that could lead to innovative treatment strategies aimed at improving patient outcomes in this challenging disease.

In holobiont, microbiota is known to play a central role on the health and immunity of its host. Then, understanding the microbiota, its dynamic according to the environmental conditions and its link to the immunity would help to react to potential dysbiosis of aquacultured species. While the gut microbiota is highly studied, in marine invertebrates the hemolymph microbiota is often set aside even if it remains an important actor of the hemolymph homeostasis. Indeed, the hemolymph harbors the factors involved in the animal homeostasis that interacts with the microbiota, the immunity. In the Southwest Pacific, the high economical valued shrimp Penaeus stylirostris is reared in two contrasted sites, in New Caledonia (NC) and in French Polynesia (FP).

We characterized the active microbiota inhabiting the hemolymph of shrimps while considering its stability during two seasons and at a one-month interval and evidenced an important microbial variability between the shrimps according to the rearing conditions and the sites. We highlighted specific biomarkers along with a common core microbiota composed of 6 ASVs. Putative microbial functions were mostly associated with bacterial competition, infections and metabolism in NC, while they were highly associated with the cell metabolism in FP suggesting a rearing site discrimination. Differential relative expression of immune effectors measured in the hemolymph of two shrimp populations from NC and FP, exhibited higher level of expression in NC compared to FP. In addition, differential relative expression of immune effectors was correlated to bacterial biomarkers based on their geographical location.

Our data suggest that, in Pacific shrimps, both the microbiota and the expression of the immune effectors could have undergone differential immunostimulation according to the rearing site as well as a geographical adaptative divergence of the shrimps as an holobiont, to their rearing sites. Further, the identification of proxies such as the core microbiota and site biomarkers, could be used to guide future actions to monitor the bacterial microbiota and thus preserve the productions.

In ovo stimulation introduces bioactive compounds, such as prebiotics, probiotics, or synbiotics into incubating eggs to enhance gut health and immune system development in chickens. This study aimed to determine the genetic and environmental effects modulating responses to in ovo stimulation in commercial broilers and Green-legged Partridge-like (GP) native chickens.

Eggs were stimulated on day 12 of incubation with prebiotics (GOS-galactooligosaccharides), probiotics (Lactococcus lactis subsp. cremoris), or synbiotics (GOS + L. lactis), with controls being mock-injected. Hatched chicks were reared in group pens and challenged with lipopolysaccharide (LPS) on day 42 post-hatching. Cecal tonsils (CT) and spleens were harvested 2 h post-challenge. RT-qPCR was used to analyze the relative gene expression of cytokine genes: IL-1β, IL-2, IL-4, IL-6, IL-10, IL-12p40, and IL-17.

The results show that genotype influenced the expression of all immune-related genes, with broiler chickens exhibiting stronger innate inflammatory responses than native chickens. LPS induced both mucosal (CT) and systemic (spleen) immune responses in broilers but only systemic (spleen) responses in native chickens.

In ovo stimulation had less of an impact on cytokine gene expression than LPS challenge. Broilers expressed higher inflammatory immune responses than GP native chickens.

It is largely unknown whether the gut microbiome regulates immune responses in humans. We determined relationships between the microbiota composition and immunological phenotypes in 108 healthy volunteers, using 16S sequencing, an ex vivo monocyte challenge model, and an in vivo challenge model of systemic inflammation induced by lipopolysaccharide (LPS).

Significant associations were observed between the microbiota composition and ex vivo monocytic cytokine responses induced by several stimuli, most notably IL-10 production induced by Pam3Cys, Pseudomonas aeruginosa and Candida albicans, although the explained variance was rather low (0.3-4.8%). Furthermore, a number of pairwise correlations between Blautia, Bacteroides and Prevotella genera and cytokine production induced by these stimuli were identified. LPS administration induced a profound transient in vivo inflammatory response. A second LPS challenge one week after the first resulted in a severely blunted response, reflecting endotoxin tolerance. However, no significant relationships between microbiota composition and in vivo parameters of inflammation or tolerance were found (explained variance ranging from 0.4 to 1.5%, ns).

The gut microbiota composition explains a limited degree of variance in ex vivo monocytic cytokine responses to several pathogenic stimuli, but no relationships with the LPS-induced in vivo immune response or tolerance was observed.

This review aims to provide an overview of the current knowledge about microbiota-targeted therapies in sepsis, and calls out - despite recent negative studies - not to halt our efforts of translating these tools into regular medical practice.

The intestinal microbiome has an important role in shaping our immune system, and microbiota-derived metabolites prime innate and adaptive inflammatory responses to infectious pathogens. Microbiota composition is severely disrupted during sepsis, which has been linked to increased risk of mortality and secondary infections. However, efforts of using these microbes as a tool for prognostic or therapeutic purposes have been unsuccessful so far, and recent trials studying the impact of probiotics in critical illness did not improve patient outcomes. Despite these negative results, researchers must continue their attempts of harnessing the microbiome to improve sepsis survival in patients with a high risk of clinical deterioration. Promising research avenues that could potentially benefit sepsis patients include the development of next-generation probiotics, use of the microbiome as a theranostic tool to direct therapy, and addressing the restoration of microbial communities following ICU discharge.

Although research focused on microbiome-mediated therapy in critically ill patients has not yielded the results that were anticipated, we should not abandon our efforts to translate promising preclinical findings into clinical practice.