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The regulation of vascular tone by perivascular tissues is a complex interplay of various paracrine factors. Here, we investigate the anti-contractile effect of skeletal muscle surrounding the femoral and carotid arteries and its underlying mechanisms. Using male and female Wistar rats, we demonstrated that serotonin, phenylephrine, and U-46619 induced a concentration-dependent vasoconstrictor response in femoral artery rings. Interestingly, this response was diminished in the presence of surrounding femoral skeletal muscle, irrespective of sex. No anti-contractile effect was observed when the carotid artery was exposed to its surrounding skeletal muscle. The observed effect in the femoral artery persisted even in the absence of endothelium and when the muscle was detached from the artery. Furthermore, the skeletal muscle surrounding the femoral artery was able to promote an anti-contractile effect in three other vascular beds (basilar, mesenteric, and carotid arteries). Using inhibitors of lactate dehydrogenase and the 1/4 monocarboxylate transporter, we confirmed the involvement of lactate, as both inhibitors were able to abolish the anti-contractile effect. However, lactate did not directly promote vasodilation; rather, it exerted its effect by activating 5' AMP-activated protein kinase (AMPK) and neuronal nitric oxide synthase (NOS1) in the skeletal muscle. Accordingly, Nω-propyl L-arginine, a specific inhibitor of NOS1, prevented the anti-contractile effect, as well as lactate-induced phosphorylation of NOS1 at the stimulatory serine site (1417) in primary skeletal muscle cells. Phosphorylation of NOS1 was reduced in the presence of Bay-3827, a selective AMPK inhibitor. In conclusion, femoral artery-associated skeletal muscle is a potent paracrine and endocrine organ that influences vascular tone in both sexes. Mechanistically, the anti-contractile effect involves muscle fiber type and/or its anatomical location but not the type of artery or its related vascular endothelium. Finally, the femoral artery anti-contractile effect is mediated by the lactate-AMPK-phospho-NOS1Ser1417-NO signaling axis., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Physiological Society.)

Cancer cachexia, or the unintentional loss of body weight in patients with cancer, is a multiorgan and multifactorial syndrome with a complex and largely unknown etiology; however, metabolic dysfunction and inflammation remain hallmarks of cancer-associated wasting. Although cachexia manifests with muscle and adipose tissue loss, perturbations to the gastrointestinal tract may serve as the frontline for both impaired nutrient absorption and immune-activating gut dysbiosis. Investigations into the gut microbiota have exploded within the past two decades, demonstrating multiple gut-tissue axes; however, the link between adipose and skeletal muscle wasting and the gut microbiota with cancer is only beginning to be understood. Furthermore, the most used anticancer drugs (e.g. chemotherapy and immune checkpoint inhibitors) negatively impact gut homeostasis, potentially exacerbating wasting and contributing to poor patient outcomes and survival. In this review, we 1 ) highlight our current understanding of the microbial changes that occur with cachexia, 2 ) discuss how microbial changes may contribute to adipose and skeletal muscle wasting, and 3 ) outline study design considerations needed when examining the role of the microbiota in cancer-induced cachexia.

Gastrointestinal (GI) cancers cause one-third of all cancer-related deaths worldwide. Natural compounds are emerging as alternative or adjuvant cancer therapies given their distinct advantage of manipulating multiple pathways to both suppress tumor growth and alleviate cancer comorbidities; however, concerns regarding efficacy, bioavailability, and safety are barriers to their development for clinical use. Emodin (1,3,8-trihydroxy-6-methylanthraquinone), a Chinese herb-derived anthraquinone, has been shown to exert anti-tumor effects in colon, liver, and pancreatic cancers. While the mechanisms underlying emodin's tumoricidal effects continue to be unearthed, recent evidence highlights a role for mitochondrial mediated apoptosis, modulated stress and inflammatory signaling pathways, and blunted angiogenesis. The goals of this review are to (1) highlight emodin's anti-cancer properties within GI cancers, (2) discuss the known anti-cancer mechanisms of action of emodin, (3) address emodin's potential as a treatment complementary to standard chemotherapeutics, (4) assess the efficacy and bioavailability of emodin derivatives as they relate to cancer, and (5) evaluate the safety of emodin.

Background: Emodin, a natural anthraquinone, has shown potential as an effective therapeutic agent in the treatment of many diseases including cancer. However, its clinical development is hindered by uncertainties surrounding its potential toxicity. The primary purpose of this study was to uncover any potential toxic properties of emodin in mice at doses that have been shown to have efficacy in our cancer studies. In addition, we sought to assess the time course of emodin clearance when administered both intraperitoneally (I.P.) and orally (P.O.) in order to begin to establish effective dosing intervals., Methods: We performed a subchronic (12 week) toxicity study using 3 different doses of emodin (~ 20 mg/kg, 40 mg/kg, and 80 mg/kg) infused into the AIN-76A diet of male and female C57BL/6 mice (n = 5/group/sex). Body weight and composition were assessed following the 12-week feeding regime. Tissues were harvested and assessed for gross pathological changes and blood was collected for a complete blood count and evaluation of alanine transaminase (ALT), aspartate transaminase (AST) and creatinine. For the pharmacokinetic study, emodin was delivered intraperitoneally I.P. or P.O. at 20 mg/kg or 40 mg/kg doses to male and female mice (n = 4/group/sex/time-point) and circulating levels of emodin were determined at 1, 4 and 12 h following administration via liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis., Results: We found that 12 weeks of low (20 mg/kg), medium (40 mg/kg), or high (80 mg/kg) emodin feeding did not cause pathophysiological perturbations in major organs. We also found that glucuronidated emodin peaks at 1 h for both I.P. and P.O. administered emodin and is eliminated by 12 h. Interestingly, female mice appear to metabolize emodin at a faster rate than male mice as evidenced by greater levels of glucuronidated emodin at the 1 h time-point (40 mg/kg for both I.P. and P.O. and 20 mg/kg I.P.) and the 4-h time-point (20 mg/kg I.P.)., Conclusions: In summary, our studies establish that 1) emodin is safe for use in both male and female mice when given at 20, 40, and 80 mg/kg doses for 12 weeks and 2) sex differences should be considered when establishing dosing intervals for emodin treatment.

5 fluorouracil (5FU) has been a first-choice chemotherapy drug for several cancer types (e.g., colon, breast, head, and neck); however, its efficacy is diminished by patient acquired resistance and pervasive side effects. Leukopenia is a hallmark of 5FU; however, the impact of 5FU-induced leukopenia on healthy tissue is only becoming unearthed. Recently, skeletal muscle has been shown to be impacted by 5FU in clinical and preclinical settings and weakness and fatigue remain among the most consistent complaints in cancer patients undergoing chemotherapy. Monocytes, or more specifically macrophages, are the predominate immune cell in skeletal muscle which regulate turnover and homeostasis through removal of damaged or old materials as well as coordinate skeletal muscle repair and remodeling. Whether 5FU-induced leukopenia extends beyond circulation to impact resident and infiltrating skeletal muscle immune cells has not been examined. The purpose of the study was to examine the acute effects of 5FU on resident and infiltrating skeletal muscle monocytes and inflammatory mediators. Male C57BL/6 mice were given a physiologically translatable dose (35 mg/kg) of 5FU, or PBS, i.p. once daily for 5 days to recapitulate 1 dosing cycle. Our results demonstrate that 5FU reduced circulating leukocytes, erythrocytes, and thrombocytes while inducing significant body weight loss (>5%). Flow cytometry analysis of the skeletal muscle indicated a reduction in total CD45+ immune cells with a corresponding decrease in total CD45+CD11b+ monocytes. There was a strong relationship between circulating leukocytes and skeletal muscle CD45+ immune cells. Skeletal muscle Ly6c High activated monocytes and M1-like macrophages were reduced with 5FU treatment while total M2-like CD206+CD11c- macrophages were unchanged. Interestingly, 5FU reduced bone marrow CD45+ immune cells and CD45+CD11b+ monocytes. Our results demonstrate that 5FU induced body weight loss and decreased skeletal muscle CD45+ immune cells in association with a reduction in infiltrating Ly6c High monocytes. Interestingly, the loss of skeletal muscle immune cells occurred with bone marrow cell cycle arrest. Together our results highlight that skeletal muscle is sensitive to 5FU's off-target effects which disrupts both circulating and skeletal muscle immune cells., Competing Interests: BV, DF, and EM were employed by the company AcePre LLC. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2020 VanderVeen, Sougiannis, Velazquez, Carson, Fan and Murphy.)

Weight fluctuations are common among individuals with obesity and are associated with increased morbidity. We examined adipose tissue immune and inflammatory markers in mice following weight loss and partial weight regain. Male C57BL/6 mice were randomized into four groups ( n = 8-10/group): low-fat diet for 32 wk (LFD), high-fat diet for 32 wk (HFD), LFD for 28 wk and then changed to a HFD for 4 wk (LFD→H), and HFD for 21 wk and then changed to LFD for 7 wk and then changed to HFD for 4 wk (HFD→L→H). LFD→H and HFD→L→H mice did not differ in body weight, fat mass, or fat percentage; however, these parameters were greater than in LFD ( P < 0.05) but lower than in HFD ( P < 0.05). HFD→L→H mice had smaller adipocytes than HFD and LFD→H ( P < 0.05) but not LFD mice. Expressions of CD11c and CD8a genes were elevated in epididymal fat of HFD→L→H compared with LFD→H and LFD ( P < 0.05)mice. However, CD11c was lower in HFD→L→H than in HFD mice ( P < 0.05), but there was no difference in CD8a between these groups. TNFα and IFNγ expressions were increased in HFD→L→H compared with LFD and LFD→H mice ( P < 0.05), although HFD→L→H had lower expression of these cytokines than HFD ( P < 0.05). IL-1β was greater in HFD→L→H compared with LFD ( P < 0.05) but was not different from LFD→H or HFD mice. Monocyte chemoattractant protein-1 was lower ( P < 0.05) in HFD→L→H than in LFD→H. These data reinforce the importance of maintaining a body weight in the range that is recommended for optimal health to reduce immune and inflammatory perturbations associated with obesity. NEW & NOTEWORTHY We examined the immune and inflammatory status of adipose tissue in mice after they underwent weight loss followed by partial weight regain. We show an increase in selected immune cells and inflammatory mediators, in high-fat diet-fed mice that had prior exposure to a high-fat diet. Although weight fluctuations appear to exacerbate immune cell abundance and inflammation in adipose tissue, severity is less than in mice that were exposed to sustained high-fat diet feedings.

Emerging evidence suggests that gut microbiota may influence the response to chemotherapy. We sought to characterize the effects of 5 fluorouracil (5FU) chemotherapy on colon inflammation and functional measures in colorectal cancer (CRC) and to further determine whether gut microbiota can influence this response. 50 C57BL/6 were randomized into four groups; Control + Vehicle (n = 10), Control + 5FU (n = 10), AOM/DSS + Vehicle (n = 15), and AOM/DSS + 5FU (n = 15). CRC was induced chemically by a single 10 mg/kg injection of azoxymethane (AOM) followed by two cycles (2% and 1%) of dextran sodium sulfate (DSS). Mice were then treated with 3 cycles of vehicle or 5FU (cycle 1: 40 mg/kg, cycle 2 + 3: 20 mg/kg). Functional tests (grip strength and run-to-fatigue) were performed prior to 5FU treatment (baseline) and at the completion of the second cycle of 5FU. Following the third 5FU cycle, mice were euthanized and the colon was evaluated for expression of inflammatory genes using RT-qPCR and stool samples were profiled using 16S rRNA sequencing. A second experiment used fecal microbiota transplantation from 5FU treated mice to control mice (n = 10-15/group) to determine whether 5FU associated changes in the microbiota could influence functional measures and colon inflammation. 5FU reduced grip strength (p < 0.05) and caused a trending decrease in run-to-fatigue performance in cancer mice (p = 0.06). Select intestinal inflammatory genes were significantly elevated with 5FU treatment and this was further exacerbated with cancer (p < 0.05). Microbiota analysis revealed increased dissimilarity and alterations in bacterial taxonomy in 5FU and AOM/DSS-treated mice (p < 0.05). Fecal transplant from 5FU treated mice reduced functional performance (p < 0.05) and altered select colon inflammatory markers (p < 0.05). This study provides evidence of an effect of 5FU on inflammatory responses and functional measures in a mouse model of CRC and suggests that gut microbes may play a role in some, but not all, 5FU related perturbations., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Obesity is characterized by chronic low-grade, systemic inflammation, altered gut microbiota, and gut barrier disruption. Additionally, obesity is associated with increased activity of endocannabinoid system (eCB). However, the clear connection between gut microbiota and the eCB system in the regulation of energy homeostasis and adipose tissue inflammation and metabolism, remains to be established. We investigated the effect of treatment of mice with a cannabinoid receptor 1 (CB1) antagonist on Diet-Induced Obesity (DIO), specifically whether such a treatment that blocks endocannabinoid activity can induce changes in gut microbiota and anti-inflammatory state in adipose tissue. Blockade of CB1 attenuated DIO, inflammatory cytokines and trafficking of M1 macrophages into adipose tissue. Decreased inflammatory tone was associated with a lower intestinal permeability and decreased metabolic endotoxemia as evidenced by reduced plasma LPS level, and improved hyperglycemia and insulin resistance. 16S rRNA metagenomics sequencing revealed that CB1 blockade dramatically increased relative abundance of Akkermansia muciniphila and decreased Lanchnospiraceae and Erysipelotrichaceae in the gut. Together, the current study suggests that blocking of CB1 ameliorates Diet-Induced Obesity and metabolic disorder by modulating macrophage inflammatory mediators, and that this effect is associated with alterations in gut microbiota and their metabolites.

Purpose of Review: This review will examine the recent scientific literature surrounding high-fat-diet (HFD)-induced alterations in gut microbiota and subsequent development of obesity and chronic disease risk., Recent Findings: Excessive consumption of HFDs has undoubtedly contributed to the obesity epidemic. The mechanisms responsible for this relationship are, however, likely to be more complex than the simple concept of energy balance. In fact, emerging literature has implicated HFD-induced alterations in gut microbiota in the obesity epidemic. HFD consumption generally leads to a decrease in Bacteroidetes and an increase in Firmicutes, alterations that have been associated with obesity and subsequent development of chronic diseases. Potential mechanisms for this effect include an improved capacity for energy harvest and storage, and enhanced gut permeability and inflammation. We highlight the most important recent advances linking HFD-induced dysbiosis to obesity, explore the possible mechanisms for this effect, examine the implications for disease development, and evaluate the possibility of therapeutic targeting of the gut microbiome to reduce obesity., Summary: A better understanding of the mechanisms linking HFD to alterations in gut microbiota is necessary to allow for the regulation of dysbiosis and ensuing promotion of antiobesity effects.

Unlabelled: Chronic neuropathic pain is often difficult to treat with current pain medications. Gene therapy is presently being explored as a therapeutic approach for the treatment of neuropathic and cancer pain. In this study, we sought to use an injury-specific promoter to deliver the mu-opioid receptor (MOR) transgene such that expression would occur during the injured state only in response to release of injury-specific galanin. To determine whether an injury-specific promoter can produce neuron-specific MOR expression and enhanced antinociception, we compared animals infected with a galanin promoter virus (galMOR) or a human cytomegalovirus promoter virus (cmvMOR). In behavioral assays, we found an earlier onset and a larger magnitude of antinociception in animals infected with galMOR compared with cmvMOR. Immunohistochemical analysis of dorsal root ganglion neurons revealed a significant increase in MOR-positive staining in cmvMOR- and galMOR-treated mice. Spinal cord sections from galMOR-treated mice showed a greater increase in density but not area of MOR-positive staining. These results suggest that using injury-specific promoters to drive gene expression in primary afferent neurons can influence the onset and magnitude of antinociception in a rodent model of neuropathic pain and can be used to upregulate MOR expression in populations of neurons that are potentially injury specific., Perspective: An injury-specific promoter (galMOR) was used to drive MOR expression in a population- and injury-specific manner. GalMOR increased antinociception and density of MOR staining in the spinal cord. This article presents evidence that promoter selection is an important component in successful gene expression in an injury- and population-specific manner., (Copyright © 2015 American Pain Society. Published by Elsevier Inc. All rights reserved.)