A novel treatment to enhance survival for end stage triple negative breast cancer using repurposed veterinary anthelmintics combined with gut‑supporting/immune enhancing molecules

Patients with end‑stage metastatic disease have limited treatment options and those diagnosed with triple negative breast cancer (Her2, Estrogen receptor, Progesterone receptor) have a poor prognosis. Using a triple negative mammary tumor model selected for brain metastasis (4T1Br4) in the mouse, treatment options that may increase survival when therapeutics are applied at post‑metastasis were assessed. Anti‑parasitic benzimidazoles (BZs) destabilize microtubules, inhibit metabolic pathways, reduce cell proliferation, and induce apoptosis in tumor cells. Co‑administration of two BZs was selected, oxfendazole (OFZ) and parbendazole (PBZ), shown to overcome resistance development in anthelmintic effects by imposing metabolic delay to assess if multiple BZ approach is also suitable to enhance anticancer effects. It has been previously reported that treatment of mammary tumor‑bearing mice at an early stage with chitin microparticles (CMPs) decreased tumor growth and metastases by enhancing both innate M1 macrophage and TH1 adaptive immune response. Oral administration of CMPs was previously revealed to affect the gut in intestinal inflammation. A combination BZ (OFZ/PBZ) and CMP treatment was tested to target tumor development and metastasis and effects were compared in response to monotherapies of the same compounds or to untreated mice. The results demonstrated increased survival, decreased tumor cell proliferation, decreased metastasis in lungs and brain, increased levels of fecal SCFAs butyric, acetic, propionic and valeric acids with increased butyric and propionic acid levels in brain biopsies in combination treated compared with untreated mice. At the primary tumor, SCFA receptor FFAR2 expression was increased in combination treatment compared with untreated mice, suggestive of a non‑invasive cancer phenotype. The superior cytotoxic effects of OFZ/PBZ were confirmed as opposed to single treatment with OFZ or PBZ using 3D spheroids generated from a human breast cancer cell line, MDA‑MB‑468. These data are compelling for treatment option possibility even at late stages of metastasized breast cancer.

Intestinal FFA2 promotes obesity by altering food intake in Western diet-fed mice

Short-chain fatty acids (SCFAs) are key nutrients that play a diverse set of roles in physiological function, including regulating metabolic homeostasis. Generated through the fermentation of dietary fibers in the distal colon by the gut microbiome, SCFAs and their effects are partially mediated by their cognate receptors, including free fatty acid receptor 2 (FFA2). FFA2 is highly expressed in the intestinal epithelial cells, where its putative functions are controversial, with numerous in vivo studies relying on global knockout mouse models to characterize intestine-specific roles of the receptor. Here, we used the Villin-Cre mouse line to generate a novel, intestine-specific knockout mouse model for FFA2 (Vil-FFA2) to investigate receptor function within the intestine. Because dietary changes are known to affect the composition of the gut microbiome, and can thereby alter SCFA production, we performed an obesogenic challenge on male Vil-FFA2 mice and their littermate controls (FFA2-floxed, FFA2fl/fl) to identify physiological changes on a high-fat, high-sugar 'Western diet' (WD) compared to a low-fat control diet (CD). We found that the WD-fed Vil-FFA2 mice were transiently protected from the obesogenic effects of the WD and had lower fat mass and improved glucose homeostasis compared to the WD-fed FFA2fl/fl control group during the first half of the study. Additionally, major differences in respiratory exchange ratio and energy expenditure were observed in the WD-fed Vil-FFA2 mice, and food intake was found to be significantly reduced at multiple points in the study. Taken together, this study uncovers a novel role of intestinal FFA2 in mediating the development of obesity.

Gut Dysbiosis during Influenza Contributes to Pulmonary Pneumococcal Superinfection through Altered Short-Chain Fatty Acid Production

Secondary bacterial infections often complicate viral respiratory infections. We hypothesize that perturbation of the gut microbiota during influenza A virus (IAV) infection might favor respiratory bacterial superinfection. Sublethal infection with influenza transiently alters the composition and fermentative activity of the gut microbiota in mice. These changes are attributed in part to reduced food consumption. Fecal transfer experiments demonstrate that the IAV-conditioned microbiota compromises lung defenses against pneumococcal infection. In mechanistic terms, reduced production of the predominant short-chain fatty acid (SCFA) acetate affects the bactericidal activity of alveolar macrophages. Following treatment with acetate, mice colonized with the IAV-conditioned microbiota display reduced bacterial loads. In the context of influenza infection, acetate supplementation reduces, in a free fatty acid receptor 2 (FFAR2)-dependent manner, local and systemic bacterial loads. This translates into reduced lung pathology and improved survival rates of double-infected mice. Lastly, pharmacological activation of the SCFA receptor FFAR2 during influenza reduces bacterial superinfection.

FFA2 activation combined with ulcerogenic COX inhibition induces duodenal mucosal injury via the 5-HT pathway in rats

Serotonin (5-HT), predominantly synthesized and released by enterochromaffin cells, is implicated in gastrointestinal symptoms such as emesis, abdominal pain, and diarrhea. Because luminal short-chain fatty acids (SCFAs) release 5-HT from enterochromaffin cells, which express the SCFA receptor free fatty acid receptor 2 (FFA2) in rat duodenum, we examined the effects of the selective FFA2 agonist phenylacetamide-1 (PA1) on duodenal 5-HT release with consequent bicarbonate secretion [duodenal bicarbonate secretion (DBS)] and on indomethacin (IND)-induced enteropathy. Intestinal injury was induced by IND (10 mg/kg sc) with or without PA1. We measured DBS in vivo in a duodenal loop perfused with PA1 while measuring 5-HT released in the portal vein. Duodenal blood flow was measured by laser-Doppler flowmetry. IND induced small intestinal ulcers with duodenal sparing. PA1 given with IND (IND + PA1) dose dependently induced duodenal erosions. IND + PA1-induced duodenal lesions were inhibited by the FFA2 antagonist GLPG-0974, ondansetron, or omeprazole but not by RS-23597 or atropine. Luminal perfusion of PA1 augmented DBS accompanied by increased portal blood 5-HT concentrations with approximately eight times more release at 0.1 mM than at 1 µM, with the effects inhibited by coperfusion of GLPG-0974. Luminal PA1 at 1 µM increased, but at 0.1 mM diminished, duodenal blood flow. Cosuperfusion of PA1 (0.1 mM) decreased acid-induced hyperemia, further reduced by IND pretreatment but restored by ondansetron. These results suggest that, although FFA2 activation enhances duodenal mucosal defenses, FFA2 overactivation during ulcerogenic cyclooxygenase inhibition may increase the vulnerability of the duodenal mucosa to gastric acid via excessive 5-HT release and 5-HT₃ receptor activation, implicated in foregut-related symptoms such as emesis and epigastralgia.NEW & NOTEWORTHY Luminal free fatty acid receptor 2 agonists stimulate enterochromaffin cells and release serotonin, which enhances mucosal defenses in rat duodenum. However, overdriving serotonin release with high luminal concentrations of free fatty acid 2 ligands such as short-chain fatty acids injures the mucosa by decreasing mucosal blood flow. These results are likely implicated in serotonin-related dyspeptic symptom generation because of small intestinal bacterial overgrowth, which is hypothesized to generate excess SCFAs in the foregut, overdriving serotonin release from enterochromaffin cells.

Free fatty acid receptor 2, a candidate target for type 1 diabetes, induces cell apoptosis through ERK signaling

Recent reports have highlighted the roles of free fatty acid receptor 2 (FFAR2) in the regulation of metabolic and inflammatory processes. However, the potential function of FFAR2 in type 1 diabetes (T1D) remains unexplored. Our results indicated that the mRNA level of FFAR2 was upregulated in peripheral blood mononuclear cells of T1D patients. The human FFAR2 promoter regions were cloned, and luciferase reporter assays revealed that NFκB activation induced FFAR2 expression. Furthermore, we showed that FFAR2 activation by overexpression induced cell apoptosis through ERK signaling. Finally, treatment with the FFAR2 agonists acetate or phenylacetamide 1 attenuated the inflammatory response in multiple-low-dose streptozocin-induced diabetic mice, and improved the impaired glucose tolerance. These results indicate that FFAR2 may play a protective role by inducing apoptosis of infiltrated macrophage in the pancreas through its feedback upregulation and activation, thus, in turn, improving glucose homeostasis in diabetic mice. These findings highlight FFAR2 as a potential therapeutic target of T1D, representing a link between immune response and glucose homeostasis.