Effect of acetylcholinesterase inhibition on immune cells in the murine intestinal mucosa.

The gastrointestinal tract (GI) is the largest immune organ whose function is controlled by a complex network of neurons from the enteric nervous system (ENS) as well as the sympathetic and parasympathetic system. Evolving evidence indicates that cross-communication between gut-innervating neurons and immune cells regulates many essential physiological functions including protection against mucosal infections. We previously demonstrated that following paraoxon treatment, 70 % of the mice were able to survive an oral infection with S. typhimurium, a virulent strain of Salmonella enterica serovar Typhimurium. The present study aims to investigate the effect that rivastigmine, a reversible AChE inhibitor used for the treatment of neurodegenerative diseases, has on the murine immune defenses of the intestinal mucosa. Our findings show that, similar to what is observed with paraoxon, administration of rivastigmine promoted the release of secretory granules from goblet and Paneth cells, resulting in increased mucin layer. Surprisingly, however, and unlike paraoxon, rivastigmine treatment did not affect overall mortality of infected mice. In order to investigate the mechanistic basis for the differential effects observed between paraoxon and rivastigmine, we used multi-color flowcytometric analysis to characterize the immune cell landscape in the intraepithelial (IE) and lamina propria (LP) compartments of intestinal mucosa. Our data indicate that treatment with paraoxon, but not rivastigmine, led to an increase of resident CD3+CD8+ T lymphocytes in the ileal mucosa (epithelium and lamina propria) and CD11b- CD11c+ dendritic cells in the LP. Our findings indicate the requirement for persistent cholinergic pathway engagement to effect a change in the cellular landscape of the mucosal tissue that is necessary for protection against lethal bacterial infections. Moreover, optimal protection requires a collaboration between innate and adaptive mucosal immune responses in the intestine.

Oral administration of Manuka honey induces IFNγ-dependent resistance to tumor growth that correlates with beneficial modulation of gut microbiota composition.

Background: To investigate the potential of Manuka honey (MH) as an immunomodulatory agent in colorectal cancer (CRC) and dissect the underlying molecular and cellular mechanisms. Methods: MH was administered orally over a 4 week-period. The effect of MH treatment on microbiota composition was studied using 16S rRNA sequencing of fecal pellets collected before and after treatment. Pretreated mice were implanted with CRC cells and followed for tumor growth. Tumors and lymphoid organs were analyzed by flow cytometry (FACS), immunohistochemistry and qRT-PCR. Efficacy of MH was also assessed in a therapeutic setting, with oral treatment initiated after tumor implantation. We utilized IFNγ-deficient mice to determine the importance of interferon signaling in MH-induced immunomodulation. Results: Pretreatment with MH enhanced anti-tumor responses leading to suppression of tumor growth. Evidence for enhanced tumor immunogenicity included upregulated MHC class-II on intratumoral macrophages, enhanced MHC class-I expression on tumor cells and increased infiltration of effector T cells into the tumor microenvironment. Importantly, oral MH was also effective in retarding tumor growth when given therapeutically. Transcriptomic analysis of tumor tissue highlighted changes in the expression of various chemokines and inflammatory cytokines that drive the observed changes in tumor immunogenicity. The immunomodulatory capacity of MH was abrogated in IFNγ-deficient mice. Finally, bacterial 16S rRNA sequencing demonstrated that oral MH treatment induced unique changes in gut microbiota that may well underlie the IFN-dependent enhancement in tumor immunogenicity. Conclusion: Our findings highlight the immunostimulatory properties of MH and demonstrate its potential utilization in cancer prevention and treatment.

Ambrisentan, an endothelin receptor type A-selective antagonist, inhibits cancer cell migration, invasion, and metastasis.

Several studies reported a central role of the endothelin type A receptor (ETAR) in tumor progression leading to the formation of metastasis. Here, we investigated the in vitro and in vivo anti-tumor effects of the FDA-approved ETAR antagonist, Ambrisentan, which is currently used to treat patients with pulmonary arterial hypertension. In vitro, Ambrisentan inhibited both spontaneous and induced migration/invasion capacity of different tumor cells (COLO-357 metastatic pancreatic adenocarcinoma, OvCar3 ovarian carcinoma, MDA-MB-231 breast adenocarcinoma, and HL-60 promyelocytic leukemia). Whole transcriptome analysis using RNAseq indicated Ambrisentan's inhibitory effects on the whole transcriptome of resting and PAR2-activated COLO-357 cells, which tended to normalize to an unstimulated profile. Finally, in a pre-clinical murine model of metastatic breast cancer, treatment with Ambrisentan was effective in decreasing metastasis into the lungs and liver. Importantly, this was associated with a significant enhancement in animal survival. Taken together, our work suggests a new therapeutic application for Ambrisentan in the treatment of cancer metastasis.