Disruption of ZO-1/claudin-4 interaction in relation to inflammatory responses in methotrexate-induced intestinal mucositis

Updated perspectives on the contribution of the microbiome to the pathogenesis of mucositis using the MASCC/ISOO framework

Advances in the treatment of cancer have significantly improved mortality rates; however, this has come at a cost, with many treatments still limited by their toxic side effects. Mucositis in both the mouth and gastrointestinal tract is common following many anti-cancer agents, manifesting as ulcerative lesions and associated symptoms throughout the alimentary tract. The pathogenesis of mucositis was first defined in 2004 by Sonis, and almost 20 years on, the model continues to be updated reflecting ongoing research initiatives and more sophisticated analytical techniques. The most recent update, published by the Multinational Association for Supportive Care in Cancer and the International Society for Oral Oncology (MASCC/ISOO), highlights the numerous co-occurring events that underpin mucositis development. Most notably, a role for the ecosystem of microorganisms that reside throughout the alimentary tract (the oral and gut microbiota) was explored, building on initial concepts proposed by Sonis. However, many questions remain regarding the true causal contribution of the microbiota and associated metabolome. This review aims to provide an overview of this rapidly evolving area, synthesizing current evidence on the microbiota's contribution to mucositis development and progression, highlighting (i) components of the 5-phase model where the microbiome may be involved, (ii) methodological challenges that have hindered advances in this area, and (iii) opportunities for intervention.

Novel insights into gut health: Cilostazol strengthens gut integrity by adjusting TLR-2/NF-κB/IL-23 and CD44/AKT/GSK-3β/cyclin-D1 trajectories in methotrexate-induced mucositis model

Methotrexate (MTX)-induced gastrointestinal mucositis is a common adverse effect characterized by redox imbalance and overproduction of inflammatory mediators that perturb intestinal integrity. Currently, there is no definitive treatment for this condition and its prevention is still far beyond comprehension. Because of its pleiotropic pharmacological actions, we aimed to explore the potential mechanisms through which cilostazol (CILO) can protect against MTX-induced intestinal mucositis. Wistar rats were allocated into 4 groups, control, CILO (100 mg/kg, p.o for 14 days), MTX (7.5 mg/kg for 4 successive days), and CILO + MTX. The improving effect of CILO on the morphological structure was confirmed by an upturn in the histopathological and transition electron microscope examinations evidenced by the increased jejunal villus height/width and the crypt depth besides the maintenance of tight junctions. These findings were verified biochemically; on the molecular level, CILO reduced the MTX-induced lipid peroxidation, cleaved caspase-3, p53, and the inflammatory parameters (TLR-2, NF-κB, IL-23, TNF-α, IL-1β), while increasing the anti-inflammatory marker IL-10 and the antioxidant enzyme SOD. Moreover, CILO decreased the injurious axis AKT/GSK-3β/cyclin-D1, and CD44+, but increased the immunoexpression of the cell proliferating marker PCNA. CILO also upheld the intestinal barrier by enhancing the tight junction molecules (ZO-1, claudin-4) and the E-cadherin/β-catenin complex while abating the mesenchymal marker vimentin. In conclusion, CILO protected gut integrity by reducing the epithelial-mesenchymal transition process, the MTX-induced oxidative, apoptotic, and inflammatory mediators, and turning off the CD44/AKT/GSK-3β/cyclin D1 trajectory and intensifying the expression of PCNA.

Paeoniflorin ameliorates oxaliplatin-induced peripheral neuropathy via inhibiting neuroinflammation through influence on gut microbiota

Oxaliplatin (OXA)-induced peripheral neuropathy (OIPN) is a severe side effect that greatly limits OXA clinical use and threatens patients' life and health. Paeoniflorin exhibits extensive anti-inflammatory and neuroprotective effects, but whether it can protect against OIPN and the underlying mechanisms remain unclear. This study aimed to investigate the effects of paeoniflorin on OIPN and probe into the underlying mechanisms. The OIPN model was established through oxaliplatin injection in rats. The ameliorative effects of paeoniflorin on OIPN was assessed by nociceptive hypersensitivities through pain behavioral methods. Neuroinflammation were examined by measuring the levels of inflammatory cytokines and immune cells infiltration. The signaling pathway of TLR4/MyD88/NF-κB was evaluated by Western blotting. Gut microbial changes were detected by 16S rDNA sequencing technology. In addition, antibiotics-induced microbiota eradication and fecal microbial transplantation (FMT) were applied for exploring the function of gut microbiota in the protective effects of paeoniflorin. The results revealed that paeoniflorin significantly alleviated mechanical and cold hypersensitivity, mitigated neuroinflammation and influenced gut microbial composition in OIPN rats. Fecal microbiota transplantation further verified that gut microbiota was required for paeoniflorin ameliorating OIPN and that the underlying mechanism involved downregulation of TLR4/MyD88/NF-κB signaling. Specifically, Akkermansia, Dubosiella and Corynebacterium might serve as crucial genera regulated by paeoniflorin in the treatment of OIPN. In summary, our investigations delineate paeoniflorin's ameliorative effects on OIPN by alleviating neuroinflammation through regulations of gut microbiota. This suggests that paeoniflorin may serve as a new potential strategy for treatment of OIPN in clinical practice.

Shedding light on the molecular and regulatory mechanisms of TLR4 signaling in endothelial cells under physiological and inflamed conditions

Toll-like receptor 4 (TLR4) are part of the innate immune system. They are capable of recognizing pathogen-associated molecular patterns (PAMPS) of microbes, and damage-associated molecular patterns (DAMPs) of damaged tissues. Activation of TLR4 initiates downstream signaling pathways that trigger the secretion of cytokines, type I interferons, and other pro-inflammatory mediators that are necessary for an immediate immune response. However, the systemic release of pro-inflammatory proteins is a powerful driver of acute and chronic inflammatory responses. Over the past decades, immense progress has been made in clarifying the molecular and regulatory mechanisms of TLR4 signaling in inflammation. However, the most common strategies used to study TLR4 signaling rely on genetic manipulation of the TLR4 or the treatment with agonists such as lipopolysaccharide (LPS) derived from the outer membrane of Gram-negative bacteria, which are often associated with the generation of irreversible phenotypes in the target cells or unintended cytotoxicity and signaling crosstalk due to off-target or pleiotropic effects. Here, optogenetics offers an alternative strategy to control and monitor cellular signaling in an unprecedented spatiotemporally precise, dose-dependent, and non-invasive manner. This review provides an overview of the structure, function and signaling pathways of the TLR4 and its fundamental role in endothelial cells under physiological and inflammatory conditions, as well as the advances in TLR4 modulation strategies.

Size-specific effects of microplastics and lead on zebrafish

Microplastics (MPs) can adsorb heavy metals and induce combined toxicity to aquatic organisms. However, the combined effects on the gut-liver and gut-brain axes are yet to be fully comprehended. This study investigated the combined effects of polystyrene microplastics (PS-MPs) with two concentrations (20 and 200 μg/L) and three sizes (0.1, 10, and 250 μm) and Pb (50 μg/L) on zebrafish through gut-liver and gut-brain axes. The results showed that the combined exposure of 0.1 μm PS-MPs and lead resulted in the most significant changes to the community diversity of gut microbiota. The combined exposures of PS-MPs (0.1 μm and 250 μm PS-MPs) and Pb significantly down-regulated expression of zo-1 and occludin but increased the lipopolysaccharide content in zebrafish liver compared to the PS-MPs or Pb alone exposure groups, indicating impaired gut barrier function. Subsequent studies showed that combined exposure of PS-MPs (0.1 μm and 250 μm) and Pb combined groups induced liver inflammation through the TLR4/NF-κB pathway. Moreover, all exposure groups had an impact on the expression of genes related to bile acid metabolism (cyp7a1, fgf19, abcb11b, and slc10a2) and neurotransmitters (tph1a, tph2, pink, and trh). The findings of this study provide new evidence on the combined effects of MPs and metals, which are significant for their hazard identification and risk assessment.

The potential role of pumpkin seeds oil on methotrexate-induced lung toxicity

Many chemotherapeutic drugs cause adverse pulmonary reactions leading to severe pulmonary disease. Though methotrexate (MTX) is used for the treatment of cancer and other diseases, it is highly toxic with multiple adverse effects including pulmonary toxicity. Essential oils represent an open frontier for pharmaceutical sciences due to their wide range of pharmacological properties. Pumpkin seeds oil (PSO) was used to investigate its ability to alleviate methotrexate-induced lung toxicity in rats. Lung tissue from MTX-treated group revealed a decrease in malondialdehyde, glutathione, and nitric oxide accompanied by a marked inhibition in cholinesterase activity, and enhanced catalase activity, tumor necrosis factor-α, interleukin-6 and vascular endothelial growth factor levels. Analysis of PSO revealed that the oil was rich in hexadecanoic acid, decane methyl esters, squalene, polydecane, docosane, and other derivatives. Administration of PSO ameliorated the oxidant/antioxidant and proinflammatory changes induced by MTX in the lung tissue. Histological examinations confirmed the potency of PSO in reducing the histopathological alterations induced by MTX. Immunohistochemical analysis showed decreased nuclear factor-kappa B and caspase 3 expression after PSO. The present data indicated the protective efficiency of PSO against MTX-induced lung injury by decreasing oxidative damage, inflammation and apoptosis and could thus be recommended as an adjuvant therapy.

Cellular Distribution Pattern of tjp1 (ZO-1) in Xenopus laevis Oocytes Heterologously Expressing Claudins

Epithelial barriers constitute a fundamental requirement in every organism, as they allow the separation of different environments and set boundaries against noxious and other adverse effectors. In many inflammatory and degenerative diseases, epithelial barrier function is impaired because of a disturbance of the paracellular seal. Recently, the Xenopus laevis oocyte has been established as a heterologous expression model for the analysis of transmembrane tight junction protein interactions and is currently considered to be a suitable screening model for barrier effectors. A prerequisite for this application is a physiological anchoring of claudins to the cytoskeleton via the major scaffolding protein tjp1 (tight junction protein 1, ZO-1). We have analyzed the oocyte model with regard to the interaction of heterologously expressed claudins and tjp1. Our experiments have revealed endogenous tjp1 expression in protein and mRNA analyses of unfertilized Xenopus laevis oocytes expressing human claudin 1 (CLDN1) to claudin 5 (CLDN5). The amphibian cell model can therefore be used for the analysis of claudin interactions.

Alleviating Effect of Methionine on Intestinal Development and Intercellular Junction Induced by Nickel

The aim of this study was to investigate the alleviating effect of methionine (Met) on intestinal injury induced by nickel. The mice were divided into six groups: Met-deficient + nickel group (MDN), Met-deficient group (MD), Met + nickel group (MN), high-dose Met + nickel group (HMN), high-dose Met group (HM), and blank control group (BC). Histopathological techniques, Alcian blue-periodic acid Schiff (AB-PAS) staining, enzyme-linked immunosorbent assay (ELISA), and real-time PCR were used to study the changes of intestinal development, the number of goblet cells, and the intercellular junction. The results showed that Met can inhibit the intestinal villus length and crypt depth decreases induced by nickel and increase the index villus length and crypt depth (V/C), the number of goblet cells, and the content of diamine oxidase (DAO) and decrease the content of fatty acid binding protein2 (FABP2) and endotoxin (ET) of the intestinal mucosa damage parameters, and the mRNA expression of intercellular junction (occludin, ZO-1, claudin-1) was damaged. It is suggested that Met could help inhibit the toxic effect of nickel on the intestinal development and intercellular connection.

Ameliorating Effects of TRIM67 against Intestinal Inflammation and Barrier Dysfunction Induced by High Fat Diet in Obese Mice

Tripartite Motif 67 (TRIM67) is an important member of TRIM family proteins, which participates in different cellular processes including immune response, proliferation, differentiation, carcinogenesis, and apoptosis. In recent years, a high fat diet (HFD) has remained one of the main causes of different metabolic diseases and increases in intestinal permeability as well as inducing intestinal inflammation. The current study investigated the protective effects of TRIM67 in the ileum and colon of obese mice. 4-week-old wild-type (WT) C57BL/6N mice and TRIM67 knockout (KO) C57BL/6N mice were selected and randomly divided into four sub-groups, which were fed with control diet (CTR) or HFD for 14 weeks. Samples were collected at the age of 18 weeks for analysis. To construct an in vitro obesity model, over-expressed IPEC-J2 cells (porcine intestinal cells) with Myc-TRIM67 were stimulated with palmitic acid (PA), and its effects on the expression level of TRM67, inflammatory cytokines, and barrier function were evaluated. The KO mice showed pathological lesions in the ileum and colon and this effect was more obvious in KO mice fed with HFD. In addition, KO mice fed with a HFD or CTR diet had increased intestinal inflammation, intestinal permeability, and oxidative stress compared to that WT mice fed with these diets, respectively. Moreover, IPEC-J2 cells were transfected with TRIM67 plasmid to perform the same experiments after stimulation with PA, and the results were found consistent with the in vivo evaluations. Taken together, our study proved for the first time that HFD and TRIM67 KO mice have synergistic damaging effects on the intestine, while TRIM67 plays an important protective role in HFD-induced intestinal damage.

Protective Effects of Oxyberberine in 5-Fluorouracil-Induced Intestinal Mucositis in the Mice Model

Berberine (BBR), a major active constituent of Rhizoma coptidis, was reported to exert beneficial effects on intestinal mucositis (IM) induced by 5-fluorouracil (5-FU). However, the bioavailability of BBR is extremely low, and its metabolites were perceived to contribute to its prominent pharmacological activities. Oxyberberine (OBB) is a gut metabolite of BBR, which has been reported to have a superior anti-inflammatory effect in experimental colitis. However, its anti-inflammatory effects against 5-FU-induced IM mice have not yet been investigated. Hence, the purpose of this study was to reveal the protective effects of OBB on IM induced by 5-FU and investigate its potential underlying mechanism. The IM mice model was induced by receiving 5-FU (60 mg/kg, i.p.) for five days. Meanwhile, BBR (50 mg/kg) and OBB (12.5, 25, and 50 mg/kg) were given prior to 30 min intraperitoneal injection of 5-FU for seven days. Results indicated that OBB ameliorated body weight loss, anorexia, diarrhea, and histopathological damage in 5-FU-induced IM mice. After OBB administration, the amounts of MDA, SOD, and GSH altered by IM were remarkably restored. OBB was also observed to dramatically decrease the levels of TNF-α, IL-8, IL-6, COX-2, and iNOS and promote the release of IL-10. Besides, OBB distinctly upregulated the mRNA expressions of PCNA, ZO-1, occludin, and mucin-1, which could improve intestinal homeostasis in IM mice. OBB also blocked the activation of the upstream TLR4/MyD88 signaling pathway, and then it inhibited the phosphorylation of the NF-κB and MAPK pathways. Importantly, compared with BBR, OBB displayed a superior therapeutic effect to BBR in alleviating 5-FU-induced IM mice. These results indicated that OBB has considerable potential to become a novel candidate drug against IM.

Roles of Toll-Like Receptors in Radiotherapy- and Chemotherapy-Induced Oral Mucositis: A Concise Review

Radiotherapy and/or chemotherapy-induced oral mucositis (RIOM/CIOM) is a common complication in cancer patients, leading to negative clinical manifestations, reduced quality of life, and impacting compliance with anticancer treatment. The composition and metabolic function of the oral microbiome, as well as the innate immune response of the oral mucosa are severely altered during chemotherapy or radiotherapy, promoting the expression of inflammatory mediators by direct and indirect mechanisms. Commensal oral bacteria-mediated innate immune signaling via Toll-like receptors (TLRs) ambiguously shapes radiotherapy- and/or chemotherapy-induced oral damage. To date, there has been no comprehensive overview of the role of TLRs in RIOM/CIOM. This review aims to provide a narrative of the involvement of TLRs, including TLR2, TLR4, TLR5, and TLR9, in RIOM/CIOM, mainly by mediating the interaction between the host and microorganisms. As such, we suggest that these TLR signaling pathways are a novel mechanism of RIOM/CIOM with considerable potential for use in therapeutic interventions. More studies are needed in the future to investigate the role of different TLRs in RIOM/CIOM to provide a reference for the precise control of RIOM/CIOM.

Albiflorin ameliorates inflammation and oxidative stress by regulating the NF-κB/NLRP3 pathway in Methotrexate-induced enteritis

Methotrexate (MTX) treats various diseases but also damages intestinal barrier and leads to enteritis. Albiflorin (ALB) has a variety of pharmacological effects, including antioxidant, anti-inflammation and anti-apoptosis. In the present study, we evaluated the therapeutic effect of ALB on MTX-induced enteritis and investigated the possible mechanisms involved. Male SD rats were intraperitoneally injected with 7 mg/kg MTX for three consecutive days to establish the enteritis model. ALB (20 or 40 mg/kg/day) was intragastrically administrated since two days prior MTX treatment and lasted for six days. We found that ALB treatment increased body weight and intestinal weight of rats with MTX injection. The disease activity index (DAI) score was also decreased after ALB administration. In histological examination, ALB treatment attenuated inflammatory cells infiltration and promoted survival of goblet cells. In detection of inflammatory-associated factors, ALB treatment decreased CD68⁺ cells infiltration, inhibited myeloperoxidase activity, and suppressed intercellular cell adhesion molecule-1 and cyclooxygenase-2 expression. Additionally, ALB reduced malondialdehyde, glutathione levels, inhibited superoxide dismutase activity and suppressed reactive oxygen species production. Moreover, ALB treatment effectively inhibited NLRP3, as well as caspase 1 p20 and interleukin (IL)-1β and 18 expression. Finally, nuclear factor-κB (NF-κB) p65 phosphorylation and nuclear translocation were also demonstrated to be blocked upon ALB treatment. In conclusion, our findings indicated that ALB alleviated MTX-induced enteritis via inhibiting the NF-κB/NLRP3 pathway.

Role of IL-6/STAT3 pathway in mediating the protective effect of agomelatine against methotrexate-induced lung/intestinal tissues damage in rats

BACKGROUND

Methotrexate (MTX), an anticancer drug, has been linked to multiple organ toxicity. The drug-induced acute toxic symptoms can negatively affect the patient's commitment to the course of treatment.

MATERIALS AND METHODS

This study aimed to investigate the mitigating action of agomelatine (Ago) against MTX-induced lung and intestinal toxicity. Forty eight male Wister rats were randomized into six experimental groups: Group 1: Control; Groups 2 and 3: received Ago L&H (20/40 mg/kg, respectively by gavage); Group 4: received MTX 10 mg/kg/day, i.p. on days 7-9; Group 5: received Ago L (20 mg/kg) + MTX; Group 6: received Ago H (40 mg/kg) +MTX. The duration of the study was 10 days. Lung/intestine oxidative markers were measured. Lung/intestinal tissues IL-6, STAT3, and HO-1 levels were evaluated by ELISA. Besides, lung/intestinal tissues were examined for Histological changes, collagen fibers detection using Massonꞌs trichome stain, and immunohistochemical study using HSP70 antibody.

RESULTS

MDA, NOx, IL-6, and STAT3 levels were significantly higher in the MTX group's lungs and intestines, indicating lung and intestinal toxicity. There were substantial decreases in GSH, SOD tissue levels, and HSP 70 immunoexpression, as well as histological changes suggesting significant lung and intestinal injury. All of the above parameters improved significantly by using Ago.

CONCLUSION

By reducing oxidative stress, inflammatory processes, and modulating the IL-6/STAT3 pathway, Ago has potent ameliorative effects against MTX-induced lung/intestinal toxicities.

Knockdown of TRIM9 attenuates irinotecan‑induced intestinal mucositis in IEC‑6 cells by regulating DUSP6 expression via the P38 pathway

Intestinal mucositis is a common side effect of cancer chemotherapy and it limits the dose of chemotherapy given to a patient. Tripartite motif family (TRIM) proteins have been reported to be implicated in the regulation of cancer chemotherapy. The present study aimed to investigate the effect of TRIM9 on irinotecan-induced intestinal mucositis in the rat intestinal epithelial cell line IEC-6. The expression of several TRIMs, such as TRIM1, TRIM9, TRIM18, TRIM36, TRIM46 and TRIM67, was examined. After TRIM9 knockdown or overexpression by lentivirus infection, cell proliferation and apoptosis, epithelial barrier tight-junction proteins, inflammatory cytokines, transepithelial electrical resistance (TEER) and FITC dextran were measured. Treatment with irinotecan significantly inhibited cell proliferation and induced cell apoptosis, TRIM9 expression, intestinal mucosal barrier impairment, the levels of inflammatory cytokines and P38 phosphorylation in IEC-6 cells, while the expression levels of epithelial barrier tight-junction protein ZO-1 and Claudin-4 were decreased. Knockdown of TRIM9 partly counteracted the effect of irinotecan treatment, and inhibition of P38 potently reversed the effect of TRIM9 overexpression in IEC-6 cells. Moreover, co-immunoprecipitation showed an interaction between TRIM9 and DUSP6 in IEC-6 cells, and overexpression of DUSP6 notably counteracted the effect of TRIM9 overexpression. The results demonstrated that TRIM9 knockdown may benefit patients with intestinal mucositis by inhibiting inflammatory cytokine expression and repairing intestinal barrier functions, which was probably due to inhibition of the activation of the P38 pathway via targeting DUSP6.

Chemotherapy-Induced Intestinal Microbiota Dysbiosis Impairs Mucosal Homeostasis by Modulating Toll-like Receptor Signaling Pathways

Chemotherapy-induced intestinal mucositis, a painful debilitating condition affecting up to 40–100% of patients undergoing chemotherapy, can reduce the patients’ quality of life, add health care costs and even postpone cancer treatment. In recent years, the relationships between intestinal microbiota dysbiosis and mucositis have drawn much attention in mucositis research. Chemotherapy can shape intestinal microbiota, which, in turn, can aggravate the mucositis through toll-like receptor (TLR) signaling pathways, leading to an increased expression of inflammatory mediators and elevated epithelial cell apoptosis but decreased epithelial cell differentiation and mucosal regeneration. This review summarizes relevant studies related to the relationships of mucositis with chemotherapy regimens, microbiota, TLRs, inflammatory mediators, and intestinal homeostasis, aiming to explore how gut microbiota affects the pathogenesis of mucositis and provides potential new strategies for mucositis alleviation and treatment and development of new therapies.

FIBCD1 ameliorates weight loss in chemotherapy-induced murine mucositis

PURPOSE

Chemotherapy-induced gastrointestinal toxicity is a common adverse event during chemotherapeutic treatment. No uniformly applicable strategies exist to predict, prevent, or treat gastrointestinal toxicity. Thus, a goal of mucositis research is to identify targets for therapeutic interventions and individualized risk prediction. Fibrinogen C domain containing 1 (FIBCD1) is a transmembrane protein expressed in human intestinal epithelial cells with functions in the innate immune system. Previous observations have shown that FIBCD1 ameliorates dextran sulfate sodium (DSS)-induced intestinal inflammation in vivo. We evaluated the effect of FIBCD1 in a murine model of chemotherapy-induced gastrointestinal toxicity and inflammation.

METHODS

Transgenic (Tg) mice overexpressing FIBCD1 in the intestinal epithelium (Fibcd1Tg) and wild-type (WT) littermates (C57BL/6N) were randomized to receive an intraperitoneal injection of doxorubicin 20 mg/kg or saline and were terminated 2 or 7 days after the injection. Gastrointestinal toxicity was evaluated by weight change, intestinal length, villus height/crypt depth, and histological mucositis score. Expression of inflammatory markers (IL-6, IL-1β, and Tnfα) was measured by quantitative real-time PCR in intestinal tissue samples.

RESULTS

Following doxorubicin treatment, WT mice exhibited an increased weight loss compared with Tg littermates (p < 0.001). No differences between genotypes were seen in mucositis score, intestinal length, villus height/crypt depth, or IL-6, IL-1β, and Tnfα expression.

CONCLUSION

Our findings suggest that FIBCD1 could ameliorate chemotherapy-induced gastrointestinal toxicity by reducing weight loss; however, the mechanism of this possible protective effect remains to be defined warranting additional investigations.

Connecting the dots: Targeting the microbiome in drug toxicity

The gut microbiota has a vast influence on human health and its role in initiating, aggravating, or ameliorating diseases is beginning to emerge. Recently, its contribution to heterogeneous toxicological responses is also gaining attention, especially in drug-induced toxicity. Whether they are orally administered or not, drugs may interact with the gut microbiota directly or indirectly, which leads to altered toxicity. Present studies focus more on the unidirectional influence of how xenobiotics disturb intestinal microbial composition and functions, and thus induce altered homeostasis. However, interactions between the gut microbiota and xenobiotics are bidirectional and the impact of the gut microbiota on xenobiotics, especially on drugs, should not be neglected. Thus, in this review, we focus on how the gut microbiota modulates drug toxicity by highlighting the microbiome, microbial enzyme, and microbial metabolites. We connect the dots between drugs, the microbiome, microbial enzymes or metabolites, drug metabolites, and host toxicological responses to facilitate the discovery of microbial targets and mechanisms associated with drug toxicity. Besides this, current mainstream strategies to manipulate drug toxicity by targeting the microbiome are summarized and discussed. The review provides technical reference for the evaluation of medicinal properties in the research and development of innovative drugs, and for the future exploitation of strategies to reduce drug toxicity by targeting the microbiome.

Panax quinquefolium saponins protect against cisplatin evoked intestinal injury via ROS-mediated multiple mechanisms

BACKGROUND

Cisplatin is one of the most common chemotherapeutic drugs. Cisplatin-induced toxicity gives rise to gastrointestinal cell damage, subsequent diarrhea and vomiting, leading to the discontinuation of its clinical application in long-term cancer chemotherapy. Panax quinquefolium L., also known as American ginseng, has many pharmacological activities such as improving immunity, anti-tumor, anti-radiation and blood sugar lowering.

PURPOSE

Previously, our laboratory reported that American ginseng berry extract could alleviate chemotherapeutic agents-induced renal damage caused by cisplatin. Hence, this study further explored the protective effect of P. quinquefolium saponins (PQS) on cisplatin-induced intestinal injury in mice and the possible molecular mechanisms.

METHODS

Biochemical markers, levels of inflammatory factors, histopathological staining and western blotting were used to analyze intestinal injury based on various molecular mechanisms.

RESULTS

We demonstrated the destruction of the intestinal barrier caused by cisplatin exposure by detecting the activity of diamine oxidase (DAO) and the expression of tight junction proteins zonula occludens-1 (ZO-1) and occludin. Meanwhile, cisplatin exposure changed SOD and MDA levels in the small intestine, causing oxidative damage to the intestinal mucosa. The inflammation associated-intestinal damage was further explored by the measurement of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and analysis of nuclear factor-kappa B (NF-κB) inflammatory pathway protein expression. Moreover, apoptotic cells labeled with TUNEL staining-positive cells and activated caspase family proteins suggest that cisplatin induces intestinal apoptosis. Interestingly, PQS pretreatment significantly reversed these situations.

CONCLUSION

These evidences clearly suggest that PQS can alleviate cisplatin-induced intestinal damage by inhibiting oxidative stress, reducing the occurrence of inflammation and apoptosis, and improving intestinal barrier function.

Structural, Functional, and Metabolic Alterations in Human Cerebrovascular Endothelial Cells during Toxoplasma gondii Infection and Amelioration by Verapamil In Vitro

Toxoplasma gondii (T. gondii), the causative agent of toxoplasmosis, is a frequent cause of brain infection. Despite its known ability to invade the brain, there is still a dire need to better understand the mechanisms by which this parasite interacts with and crosses the blood–brain barrier (BBB). The present study revealed structural and functional changes associated with infection and replication of T. gondii within human brain microvascular endothelial cells (BMECs) in vitro. T. gondii proliferated within the BMECs and disrupted the integrity of the cerebrovascular barrier through diminishing the cellular viability, disruption of the intercellular junctions and increasing permeability of the BMEC monolayer, as well as altering lipid homeostasis. Proton nuclear magnetic resonance (¹H NMR)-based metabolomics combined with multivariate data analysis revealed profiles that can be attributed to infection and variations in the amounts of certain metabolites (e.g., amino acids, fatty acids) in the extracts of infected compared to control cells. Notably, treatment with the Ca²⁺ channel blocker verapamil rescued BMEC barrier integrity and restricted intracellular replication of the tachyzoites regardless of the time of treatment application (i.e., prior to infection, early- and late-infection). This study provides new insights into the structural and functional changes that accompany T. gondii infection of the BMECs, and sheds light upon the ability of verapamil to inhibit the parasite proliferation and to ameliorate the adverse effects caused by T. gondii infection.

Leucovorin ameliorated methotrexate induced intestinal toxicity via modulation of the gut microbiota

Methotrexate (MTX) is a widely used therapeutic agent for the treatment of cancer and autoimmune diseases. However, its efficacy is often limited by adverse effects, such as intestinal toxicity. Although treatment with leucovorin (LV) is the most common method to reduce the toxic effects of MTX, it may also compromise the therapeutic effects of MTX. The gut microbiome has been reported to be associated with the intestinal toxicity of MTX. In this study, the intestinal damage of MTX was ameliorated by treatment with LV. Moreover, the population, diversity, and principal components of the gut microbiota in MTX-treated mice were restored by treatment with LV. The only element of the gut microbiota that was significantly changed after treatment with LV was Bifidobacterium, and supplementation with Bifidobacterium longum ameliorated MTX-induced intestinal damage. In conclusion, our results suggest that the balance and the composition of gut microbiota have an important role in the LV-mediated protection against MTX-induced intestinal toxicity. This work provides foundation of data in support of a new potential mechanism for the prevention of MTX-induced intestinal toxicity.

Paeonol Attenuates Methotrexate-Induced Cardiac Toxicity in Rats by Inhibiting Oxidative Stress and Suppressing TLR4-Induced NF-κB Inflammatory Pathway

Methotrexate (MTX) is a commonly used chemotherapeutic agent. Oxidative stress and inflammation have been proved in the development of MTX toxicity. Paeonol is a natural phenolic compound with various pharmacological activities including antioxidant and anti-inflammatory properties. The aim of the present study was to evaluate the protective effect of paeonol against MTX-induced cardiac toxicity in rats and to evaluate the various mechanisms that underlie this effect. Paeonol (100 mg/kg) was administered orally for 10 days. MTX cardiac toxicity was induced at the end of the fifth day of the experiment, with or without paeonol pretreatment. MTX-induced cardiac damage is evidenced by a distortion in the normal cardiac histological structure, with significant oxidative and nitrosative stress shown as a significant increase in NADPH oxidase-2, malondialdehyde, and nitric oxide levels along with a decrease in reduced glutathione concentration and superoxide dismutase activity compared to the control group. MTX-induced inflammatory effects are evidenced by the increased cardiac toll-like receptor 4 (TLR4) mRNA expression and protein level as well as increased cardiac tumor necrosis factor- (TNF-) α and interleukin- (IL-) 6 levels along with increased nuclear factor- (NF-) κB/p65 immunostaining. MTX increased apoptosis as shown by the upregulation of cardiac caspase 3 immunostaining. Paeonol was able to correct the oxidative and nitrosative stress as well as the inflammatory and apoptotic parameters and restore the normal histological structure compared to MTX alone. In conclusion, paeonol has a protective effect against MTX-induced cardiac toxicity through inhibiting oxidative and nitrosative stress and suppressing the TLR4/NF-κB/TNF-α/IL-6 inflammatory pathway, as well as causing an associated reduction in the proapoptotic marker, caspase 3.

Targeting strategies for chemotherapy-induced peripheral neuropathy: does gut microbiota play a role?

Chemotherapy-induced peripheral neuropathy (CIPN) is a progressive, often irreversible condition that produces severe neurological deficits. Emerging data suggest that chemotherapy also exerts detrimental effects on gut microbiota composition and intestinal permeability, contributing to dysbiosis and inflammation. Compared with other complications associated with chemotherapy, such as diarrhoea and mucositis, CIPN is of particular concern because it is the most common reason for terminating or suspending treatment. However, specific and effective curative treatment strategies are lacking. In this review, we provide an update on current preclinical and clinical understandings about the role of gut microbiota in CIPN. The gut microbiota serves as an intersection between the microbiome-gut-brain and the neuroimmune-endocrine axis, forming a complex network that can directly or indirectly affect key components involved in the manifestations of CIPN. Herein, we discuss several potential mechanisms within the context of the networks and summarize alterations in gut microbiome induced by chemotherapeutic drugs, providing great potential for researchers to target pathways associated with the gut microbiome and overcome CIPN.

Role of toll-like receptor 4 (TLR4)-mediated interleukin-6 (IL-6) production in chemotherapy-induced mucositis

Despite significant advances in our ability to treat cancer, cytotoxic chemotherapy continues to be the mainstay treatment for many solid tumours. Chemotherapy is commonly associated with a raft of largely manageable adverse events; however, gastrointestinal (GI) toxicity (also termed mucositis) remains a significant challenge with little in the way of preventative and therapeutic options. The inability to manage GI complications likely reflects our incomplete understanding of its aetiology and the idiosyncrasies of each chemotherapeutic agent. This review highlights aims to provide a narrative for the involvement of Toll-like receptor (TLR4) in the development of chemotherapy-induced GI mucositis, an already emerging theme within this field. Particular focus will be placed upon the signalling interaction between TLR4 and interleukin (IL)-6. This parallels recent preclinical findings showing that TLR4 knockout mice, which are protected from developing severe GI mucositis, completely lack an IL-6 response. As such, we suggest that this signalling pathway presents as a novel mechanism with potential for therapeutic intervention.

Rhubarb Monomers Protect Intestinal Mucosal Barrier in Sepsis via Junction Proteins

Background:

Leakage of the intestinal mucosal barrier may cause translocation of bacteria, then leading to multiorgan failure. This study hypothesized that rhubarb monomers might protect the gut mucosal barrier in sepsis through junction proteins.

Methods:

Healthy male Sprague-Dawley rats (weighing 230–250 g) under anesthesia and sedation were subjected to cecal ligation and perforation (CLP). After surgical preparation, rats were randomly assigned to eight groups (n = 6 or 8 each group): sham group (Group A: normal saline gavage); sepsis group (Group B: normal saline gavage); Group C (intraperitoneally, dexamethasone 0.5 mg/kg) immediately after CLP surgery; and rhubarb monomer (100 mg/kg in normal saline)-treated groups (Group D: rhein; Group E: emodin; Group F: 3,8-dihydroxy-1-methyl-anthraquinone-2-carboxylic acid; Group G: 1-O-caffeoyl-2-(4-hydroxy-O-cinnamoyl)-D-glucose; and Group H: daucosterol linoleate). Animals were sacrificed after 24 h. Intestinal histology, lactulose, mannitol concentrations were measured, and zonula occludens (ZO)-1, occludin and claudin-5 transcription (polymerase chain reaction), translation (by Western blot analysis), and expression (by immunohistochemistry) were also measured.

Results:

Intestinal histology revealed injury to intestinal mucosal villi induced by sepsis in Group B, compared with Group A. Compared with Group A (0.17 ± 0.41), the pathological scores in Groups B (2.83 ± 0.41, P < 0.001), C (1.83 ± 0.41, P < 0.001), D (2.00 ± 0.63, P < 0.001), E (1.83 ± 0.41, P < 0.001), F (1.83 ± 0.75, P < 0.001), G (2.17 ± 0.41, P < 0.001), and H (1.83 ± 0.41, P < 0.001) were significantly increased. Lactulose/mannitol (L/M) ratio in Group B (0.046 ± 0.003) was significantly higher than in Group A (0.013 ± 0.001, P < 0.001) while L/M ratios in Groups C (0.028 ± 0.002, P < 0.001), D (0.029 ± 0.003, P < 0.001), E (0.026 ± 0.003, P < 0.001), F (0.027 ± 0.003, P < 0.001), G (0.030 ± 0.005, P < 0.001), and H (0.026 ± 0.002, P < 0.001) were significantly lower than that in Group B. ZO-1, occludin and claudin-5 transcription, translation, and expression in Group B were significantly lower than that in Group A (P < 0.001), but they were significantly higher in Groups C, D, E, F, G, and H than those in Group B (P < 0.05).

Conclusion:

Rhubarb monomer treatment ameliorated mucosal damage in sepsis via enhanced transcription, translation, and expression of junction proteins.

Animal models of chemotherapy-induced mucositis: translational relevance and challenges

Chemotherapy for cancer patients induces damaging tissue reactions along the epithelium of the gastrointestinal tract (GIT). This chemotherapy-induced mucositis (CIM) is a serious side effect of cytotoxic drugs, and several animal models of CIM have been developed, mainly in rodents and piglets, to help understand the progression of CIM and how to prevent it. Animal models allow highly controlled experimental conditions, detailed organ (e.g., GIT) insights, standardized, clinically relevant treatment regimens, and discovery of new biomarkers. Still, surprisingly few results from animal models have been translated into clinical CIM management and treatments. The results obtained from specific animal models can be difficult to translate to the diverse range of CIM manifestations in patients, which vary according to the antineoplastic drugs, dose, underlying (cancer) disease, and patient characteristics (e.g., age, genetics, and body constitution). Another factor that hinders the direct use of results from animals is inadequate collaboration between basic science and clinical science in relation to CIM. Here, we briefly describe CIM pathophysiology, particularly the basic knowledge that has been obtained from CIM animal models. These model studies have indicated potential new preventive and ameliorating interventions, including supplementation with natural bioactive diets (e.g., milk fractions, colostrum, and plant extracts), nutrients (e.g., polyunsaturated fatty acids, short-chain fatty acids, and glutamine), and growth factor peptides (e.g., transforming growth factor and glucagon-like peptide-2), as well as manipulations of the gut microbiota (e.g., prebiotics, probiotics, and antibiotics). Rodent CIM models allow well-controlled, in-depth studies of animals with or without tumors while pig models more easily make clinically relevant treatment regimens possible. In synergy, animal models of CIM provide the basic physiological understanding and the new ideas for treatment that are required to make competent decisions in clinical practice.

Toll-Like Receptor 4 Reduces Occludin and Zonula Occludens 1 to Increase Retinal Permeability Both in vitro and in vivo

We reported that β-adrenergic receptors regulate toll-like receptor 4 (TLR4) signaling in the retina of diabetic mice and in retinal endothelial cells (REC) and Müller cells. We hypothesized that TLR4 regulates retinal permeability both in vitro and in vivo in the retinal vasculature. We used REC cultured in normal and high-glucose conditions and TLR4 siRNA treatments for cell culture studies of permeability and protein analyses of tumor necrosis factor α, occludin, and zonula occludens 1 (ZO-1). We used endothelial cell (EC)-specific Cre-Lox TLR4 knockout mice to study retinal permeability and neuronal and vascular changes following exposure to ocular ischemia/reperfusion (I/R) used as a retinal stressor. We found that the loss of TLR4 in the EC led to the reduced permeability following I/R and fewer degenerate capillaries. Retinal permeability was increased in REC grown in high-glucose conditions but was inhibited by TLR4 siRNA treatment. High-glucose culture conditions significantly reduced occludin and ZO-1 levels in REC, and TLR4 siRNA treatment restored levels to baseline. In conclusion, these studies demonstrate that TLR4 in EC strongly regulates retinal permeability and neuronal and vascular changes following exposure to stressors such as I/R.

Tumor Necrosis Factor-Alpha Inhibitor Etanercept Does Not Alter Methotrexate-Induced Gastrointestinal Mucositis in Rats

OBJECTIVES

Gastrointestinal (GI) mucositis is a severe adverse effect of chemotherapy and radiotherapy. Proinflammatory cytokines are thought to play an important role in the pathophysiology of GI mucositis. We aimed to determine the effect of the tumor necrosis factor-alpha (TNF-α) inhibitor etanercept on the severity of mucositis in a previously established methotrexate (MTX)-induced GI mucositis rat model.

METHODS

Male Wistar rats received 60 mg/kg MTX on day 0 intravenously. Rats were treated daily with either etanercept (TNF-α inhibitor) 5 mg/kg or NaCl 0.9% subcutaneously from day -3 till day 3. Control rats received NaCl 0.9% intravenously and etanercept subcutaneously. The severity of mucositis was determined by intake, bodyweight, plasma citrulline, and by a function test (absorption of an oral glucose bolus). On day 4 and day 10 rats were terminated. Villus length, crypt length, intestinal myeloperoxidase, and plasma etanercept levels were determined.

RESULTS

The administration of MTX induced mucositis in all rats. Etanercept did not cause a change in the degree of mucositis. Bodyweight, intake, and glucose levels were not altered by etanercept; villus length was comparable; and there was no difference in myeloperoxidase and citrulline level. Etanercept levels in plasma were significantly increased in the etanercept rats (P < 0.05).

CONCLUSIONS

TNF-α inhibitor etanercept did not alter the severity of mucositis in the rat, suggesting that targeting only the inflammatory pathway of TNF-α is not effective for decreasing the severity of GI mucositis induced by high-dose MTX. Etanercept alone is not useful for the treatment of MTX-induced GI mucositis.

Effects of Ex Vivo Infection with ETEC on Jejunal Barrier Properties and Cytokine Expression in Probiotic-Supplemented Pigs

BACKGROUND AND AIM

Enterotoxigenic Escherichia coli (ETEC) strains are involved in piglet post-weaning diarrhea. Prophylactic measures including probiotics have been examined in infection experiments with live piglets. In the present study, we have tested whether the early effects of ETEC infection can also be evoked and studied in a model in which ETEC is added to whole mucosal tissues ex vivo, and whether this response can be modulated by prior supplementation of the piglets with probiotics.

METHODS

Jejunal barrier and transport properties of Enterococcus faecium-supplemented or control piglets were assessed in Ussing chambers. Part of the epithelia was challenged with an ETEC strain at the mucosal side. Fluxes of fluorescein as a marker of paracellular permeability, and the expression of selected tight junction (TJ) proteins and of proinflammatory cytokines were measured.

RESULTS

The addition of ETEC ex vivo induced an increase in transepithelial resistance peaking in the first 2 h with a concomitant reduction in fluorescein fluxes, indicating tightening effects on barrier function. The response of short-circuit current after stimulation with PGE₂ or glucose was reduced in epithelia treated with ETEC. ETEC induced a decrease in the TJ protein claudin-4 in the control diet group after 280 min and an increase in the mRNA expression of the proinflammatory cytokines interleukin-8 and TNF-α in both groups after 180 min.

CONCLUSIONS

The addition of ETEC ex vivo affected barrier function and transport properties of the jejunal tissues and enhanced cytokine expression. The differences in claudin-4 expression in the jejunum might indicate a beneficial effect of E. faecium prefeeding.

Chemotherapeutic treatment reduces circulating levels of surfactant protein-D in children with acute lymphoblastic leukemia

BACKGROUND

Surfactant protein D (SP-D) is a host defense molecule of the innate immune system that enhances pathogen clearance and modulates inflammatory responses. We hypothesized that circulating SP-D levels are associated with chemotherapy-induced mucositis and infectious morbidity in children with acute lymphoblastic leukemia (ALL).

PROCEDURE

In a prospective study, 43 children receiving treatment for ALL were monitored for mucosal toxicity from diagnosis through the induction phase of treatment. Serial blood draws were taken to determine the levels of SP-D, interleukin-6 (IL-6), C-reactive protein, and white blood cells. Data on fever, antibiotics, and bacteremia were collected. Baseline levels of circulating SP-D were compared with healthy controls.

RESULTS

Baseline values of circulating SP-D were similar to levels in healthy controls (median: 829 ng/ml vs. 657 ng/ml, respectively, P > 0.05). After initiation of chemotherapy, a significant reduction in SP-D levels was observed at all time points: 704 ng/ml at day 8, 413 ng/ml at day 15, 395 ng/ml at day 22, and 520 ng/ml at day 29 (all, P < 0.05). No significant associations between SP-D values, the occurrence of mucosal toxicity, or infectious morbidity were observed. However, loss of circulating SP-D from days 8 to 15 was associated with more systemic inflammation, and lower SP-D values at day 15 were associated with elevated intestinal mucositis scores (P < 0.05).

CONCLUSIONS

The current study supports the hypothesis that the detrimental effect of chemotherapy on patients' immune functions includes decreased circulating levels of innate mucosal molecules such as SP-D, potentially aggravating mucosal and systemic inflammatory responses.

Doxorubicin-Induced Gut Toxicity in Piglets Fed Bovine Milk and Colostrum

OBJECTIVE

Chemotherapy-induced intestinal toxicity is a common adverse effect of cancer treatment. We hypothesized that a milk diet containing bovine colostrum (BC) would reduce intestinal toxicity in doxorubicin-treated piglets.

METHODS

"Study 1" investigated intestinal parameters 9 days after a single dose of doxorubicin (1 × 75 mg/m) in piglets fed bovine milk enriched with whey protein (BM). In "study 2," responses to doxorubicin treatment were investigated in piglets receiving either 7 BC feedings per day (Only-BC, n = 13), 4 BC feedings (High-BC, n = 13), 2 BC feedings (Low-BC, n = 14), or no BC (only BM, n = 13).

RESULTS

Doxorubicin treatment induced clinical signs of intestinal toxicity with diarrhea and weight loss, relative to controls (P < 0.05). White blood cells, hexose absorptive function, plasma citrulline, weights of intestine, colon, and spleen were reduced, whereas gut permeability and plasma C-reactive protein levels were increased (all P < 0.05). Limited or no effects were observed for digestive enzymes, proinflammatory cytokines, or tight-junction proteins in the intestine. Increasing BC supplementation to doxorubicin-treated piglets (study 2) had no consistent effects on plasma C-reactive protein and citrulline levels, intestinal morphology, digestive enzymes, permeability, or proinflammatory cytokines. Only-BC pigs, however, had lower diarrhea severity toward the end of the experiment (P < 0.05 vs BM) and across the BC groups, intestinal toxicity was reduced (P < 0.01).

CONCLUSIONS

Doxorubicin-treated piglets are relevant for studying chemotherapy-induced gut toxicity. Colostrum supplementation had limited effects on doxorubicin-induced toxicity in milk-fed piglets suggesting that colostrum and a bovine milk diet enriched with whey protein provided similar protection of the developing intestine from chemotherapy-induced toxicity.

Preventing and Managing Toxicities of High-Dose Methotrexate

: High-dose methotrexate (HDMTX), defined as a dose higher than 500 mg/m2, is used to treat a range of adult and childhood cancers. Although HDMTX is safely administered to most patients, it can cause significant toxicity, including acute kidney injury (AKI) in 2%-12% of patients. Nephrotoxicity results from crystallization of methotrexate in the renal tubular lumen, leading to tubular toxicity. AKI and other toxicities of high-dose methotrexate can lead to significant morbidity, treatment delays, and diminished renal function. Risk factors for methotrexate-associated toxicity include a history of renal dysfunction, volume depletion, acidic urine, and drug interactions. Renal toxicity leads to impaired methotrexate clearance and prolonged exposure to toxic concentrations, which further worsen renal function and exacerbate nonrenal adverse events, including myelosuppression, mucositis, dermatologic toxicity, and hepatotoxicity. Serum creatinine, urine output, and serum methotrexate concentration are monitored to assess renal clearance, with concurrent hydration, urinary alkalinization, and leucovorin rescue to prevent and mitigate AKI and subsequent toxicity. When delayed methotrexate excretion or AKI occurs despite preventive strategies, increased hydration, high-dose leucovorin, and glucarpidase are usually sufficient to allow renal recovery without the need for dialysis. Prompt recognition and effective treatment of AKI and associated toxicities mitigate further toxicity, facilitate renal recovery, and permit patients to receive other chemotherapy or resume HDMTX therapy when additional courses are indicated.

IMPLICATIONS FOR PRACTICE

High-dose methotrexate (HDMTX), defined as a dose higher than 500 mg/m2, is used for a range of cancers. Although HDMTX is safely administered to most patients, it can cause significant toxicity, including acute kidney injury (AKI), attributable to crystallization of methotrexate in the renal tubular lumen, leading to tubular toxicity. When AKI occurs despite preventive strategies, increased hydration, high-dose leucovorin, and glucarpidase allow renal recovery without the need for dialysis. This article, based on a review of the current associated literature, provides comprehensive recommendations for prevention of toxicity and, when necessary, detailed treatment guidance to mitigate AKI and subsequent toxicity.

Irinotecan-induced mucositis: the interactions and potential role of GLP-2 analogues

PURPOSE

A common side effect of irinotecan administration is gastrointestinal mucositis, often manifesting as severe diarrhoea. The damage to the structure and function of the gastrointestinal tract caused by this cytotoxic agent is debilitating and often leads to alterations in patients' regimens, hospitalisation or stoppage of treatment. The purpose of this review is to identify mechanisms of irinotecan-induced intestinal damage and a potential role for GLP-2 analogues for intervention.

METHODS

This is a review of current literature on irinotecan-induced mucositis and GLP-2 analogues mechanisms of action.

RESULTS

Recent studies have found alterations that appear to be crucial in the development of severe intestinal mucositis, including early apoptosis, alterations in proliferation and cell survival pathways, as well as induction of inflammatory cascades. Several studies have indicated a possible role for glucagon-like peptide-2 analogues in treating this toxicity, due to its proven intestinotrophic, anti-apoptotic and anti-inflammatory effects in other models of gastrointestinal disease.

CONCLUSION

This review provides evidence as to why and how this treatment may improve mucositis through the possible molecular crosstalk that may be occurring in models of severe intestinal mucositis.

A novel in vitro platform for the study of SN38-induced mucosal damage and the development of Toll-like receptor 4-targeted therapeutic options

Tight junction and epithelial barrier disruption is a common trait of many gastrointestinal pathologies, including chemotherapy-induced gut toxicity. Currently, there are no validated in vitro models suitable for the study of chemotherapy-induced mucosal damage that allow paralleled functional and structural analyses of tight junction integrity. We therefore aimed to determine if a transparent, polyester membrane insert supports a polarized T84 monolayer with the phenotypically normal tight junctions. T84 cells (passage 5-15) were seeded into either 0.6 cm(2), 0.4 µm pore mixed-cellulose transwell hanging inserts or 1.12 cm(2), 0.4 µm pore polyester transwell inserts at varying densities. Transepithelial electrical resistance was measured daily to assess barrier formation. Immunofluoresence for key tight junction proteins (occludin, zonular occludens-1, claudin-1) and transmission electron microscopy were performed to assess tight junction integrity, organelle distribution, and polarity. Reverse transcription-polymerase chain reaction was performed to determine expression of toll-like receptor 4 (TLR4). Liquid chromatography was also conducted to assess SN38 degradation in this model. Polyester membrane inserts support a polarized T84 phenotype with functional tight junctions in vitro. Transmission electron microscopy indicated polarity, with apico-laterally located tight junctions. Immunofluorescence showed membranous staining for all tight junction proteins. No internalization was evident. T84 cells expressed TLR4, although this was significantly lower than levels seen in HT29 cells (P = .0377). SN38 underwent more rapid degradation in the presence of cells (-76.04 ± 1.86%) compared to blank membrane (-48.39 ± 4.01%), indicating metabolic processes. Polyester membrane inserts provide a novel platform for paralleled functional and structural analysis of tight junction integrity in T84 monolayers. T84 cells exhibit the unique ability to metabolize SN38 as well as expressing TLR4, making this an excellent platform to study clinically relevant therapeutic interventions for SN38-induced mucosal damage by targeting TLR4.

Effect ofToxoplasma gondiiinfection on the junctional complex of retinal pigment epithelial cells

Ocular toxoplasmosis is the most frequent cause of uveitis, leading to partial or total loss of vision, with the retina the main affected structure. The cells of the retinal pigment epithelium (RPE) play an important role in the physiology of the retina and formation of the blood–retinal barrier. Several pathogens induce barrier dysfunction by altering tight junction (TJ) integrity. Here, we analysed the effect of infection byToxoplasma gondiion TJ integrity in ARPE-19 cells. Loss of TJ integrity was demonstrated inT. gondii-infected ARPE-19 cells, causing increase in paracellular permeability and disturbance of the barrier function of the RPE. Confocal microscopy also revealed alteration in the TJ protein occludin induced byT. gondiiinfection. Disruption of junctional complex was also evidenced by scanning and transmission electron microscopy. Cell–cell contact loss was noticed in the early stages of infection byT. gondiiwith the visualization of small to moderate intercellular spaces. Large gaps were mostly observed with the progression of the infection. Thus, our data suggest that the alterations induced byT. gondiiin the structural organization of the RPE may contribute to retinal injury evidenced by ocular toxoplasmosis.

The effects of lycopene on intestinal injury due to methotrexate in rats

OBJECTIVE

The aim of this study was to investigate the effects of lycopene (Lyc) on methotrexate (Mtx)-induced intestinal damage in rats.

METHOD

Twenty-eight male Sprague Dawley rats were divided into four equal groups: control, Mtx, Lyc, and Mtx-L.

CONTROL GROUP

Rats were given only the vehicle. Lyc group: Rats were given Lyc (10 mg/kg) with corn oil by oral gavage for 10 days. Mtx group: Rats were injected intraperitoneally with a single dose of 20 mg/kg of Mtx and given corn oil by oral gavage. Mtx-L group: Rats were treated with Lyc (10 mg/kg) for 10 days after a single dose of Mtx (20 mg/kg). All of the rats were euthanized using terminal anesthesia, and the intestinal tissues were removed for histological examination and for pro-inflammatory cytokine measurement (tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β)), total oxidative status (TOS), total antioxidant capacity (TAC), and oxidative stress index (OSI).

RESULTS

Mtx administration increased histopathological damage and increased TNF-α, IL-1β, TOS, TAC, and OSI levels in the small intestine tissues. Lyc therapy applied to the Mtx-L group provided significant improvement in all parameters of histopathological damage to the small intestine and significantly reduced the levels of IL-1β, TOS, and OSI in the intestinal tissues.

CONCLUSIONS

The results of this study indicate that Lyc might be useful for protecting intestinal damage induced by Mtx in rats by reducing the increased oxidative stress and pro-inflammatory cytokine (IL-1β) levels.

Chemotherapy Modulates Intestinal Immune Gene Expression Including Surfactant Protein-D and Deleted in Malignant Brain Tumors 1 in Piglets

Background: Information about chemotherapy-induced intestinal gene expression may provide insight into the mechanisms underlying gut toxicity and help identify biomarkers and targets for intervention. Methods: We analyzed jejunal tissue from piglets subjected to two different, clinically relevant chemotherapy regimens: (1) busulfan plus cyclophosphamide (BUCY) and (2) doxorubicin (DOX). Results: Gene expression analysis identified 1,328 differentially expressed genes in the BUCY piglets and 594 in the DOX piglets, compared to controls. Similar changes in expression were found for 137 genes across the BUCY and DOX piglets. Selected genes of potential biological significance with a similar change in expression across the treatments were controlled by real-time polymerase chain reaction. Key innate defense molecules, including surfactant protein-D and deleted in malignant brain tumors 1, were among the upregulated genes for both treatments. Conclusion: In the developing intestine, chemotherapy increases the expression of genes related to innate immune functions involved in surveillance, protection, and homeostasis of mucosal surfaces.

Anthocyanins as inflammatory modulators and the role of the gut microbiota

The health benefits of consuming fruits that are rich in polyphenols, especially anthocyanins, have been the focus of recent in vitro and in vivo investigations. Thus, greater attention is being directed to the reduction of the inflammatory process associated with the intestinal microbiota and the mechanism underlying these effects because the microbiota has been closely associated with the metabolism of these compounds in the gastrointestinal tract. Further interest lies in the ability of these metabolites to modulate the growth of specific intestinal bacteria. Thus, this review examines studies involving the action of the anthocyanins that are present in many fruits and their effect in the modulating the inflammatory process associated with the interaction between the host and the gut microbiota. The findings of both in vitro and in vivo studies suggest a potential antiinflammatory effect of these compounds, which seem to inhibit activation of the signaling pathway mediated by the transcription factor NFκB. This effect is associated with modulation of a beneficial gut microbiota, particularly an increase in Bifidobacterium strains.

Claudin switching: Physiological plasticity of the Tight Junction

Tight Junctions (TJs) are multi-molecular complexes in epithelial tissues that regulate paracellular permeability. Within the TJ complex, claudins proteins span the paracellular space to form a seal between adjacent cells. This seal allows regulated passage of ions, fluids, and solutes, contingent upon the complement of claudins expressed. With as many as 27 claudins in the human genome, the TJ seal is complex indeed. This review focuses on changes in claudin expression within the epithelial cells of the gastrointestinal tract, where claudin differentiation results in several physiologically distinct TJs within the lifetime of the cell. We also review mechanistic studies revealing that TJs are highly dynamic, with the potential to undergo molecular remodeling while structurally intact. Therefore, physiologic Tight Junction plasticity involves both the adaptability of claudin expression and gene specific retention in the TJ; a process we term claudin switching.

Dark Agouti rat model of chemotherapy-induced mucositis: establishment and current state of the art

Mucositis is a major oncological problem. The entire gastrointestinal and genitourinary tract and also other mucosal surfaces can be affected in recipients of radiotherapy, and/or chemotherapy. Major progress has been made in recent years in understanding the mechanisms of oral and small intestinal mucositis, which appears to be more prominent than colonic damage. This progress is largely due to the development of representative laboratory animal models of mucositis. This review focuses on the development and establishment of the Dark Agouti rat mammary adenocarcinoma model by the Mucositis Research Group of the University of Adelaide over the past 20 years to characterize the mechanisms underlying methotrexate-, 5-fluorouracil-, and irinotecan-induced mucositis. It also aims to summarize the results from studies using different animal model systems to identify new molecular and cellular markers of mucositis.

Increased gut permeability and bacterial translocation after chronic chlorpyrifos exposure in rats

The epithelium's barrier function is crucial for maintaining homeostasis and preventing the passage of food antigens and luminal bacteria. This function is essentially subserved by tight junctions (TJs), multiprotein complexes located in the most apical part of the lateral membrane. Some gastrointestinal disease states are associated with elevated intestinal permeability to macromolecules. In a study on rats, we determined the influence of chronic, daily ingestion of chlorpyrifos (CPF, a pesticide that crosses the placental barrier) during pre- and postnatal periods on intestinal permeability and TJ characteristics in the pups. Fluorescein isothiocyanate (FITC)-dextran was used as a marker of paracellular transport and mucosal barrier dysfunction. Pups were gavaged with FITC-dextran solution and blood samples were collected every 30 min for 400 min and analyzed spectrofluorimetrically. At sacrifice, different intestinal segments were resected and prepared for analysis of the transcripts (qPCR) and localization (using immunofluorescence) of ZO-1, occludin and claudins (scaffolding proteins that have a role in the constitution of TJs). In rats that had been exposed to CPF in utero and after birth, we observed a progressive increase in FITC-dextran passage across the epithelial barrier from 210 to 325 min at day 21 after birth (weaning) but not at day 60 (adulthood). At both ages, there were significant changes in intestinal TJ gene expression, with downregulation of ZO-1 and occludin and upregulation of claudins 1 and 4. In some intestinal segments, there were changes in the cellular localization of ZO-1 and claudin 4 immunostaining. Lastly, bacterial translocation to the spleen was also observed. The presence of CPF residues in food may disturb epithelial homeostasis in rats. Changes in TJ protein expression and localization may be involved in gut barrier dysfunction in this model. Uncontrolled passage of macromolecules and bacteria across the intestinal epithelium may be a risk factor for digestive inflammatory diseases.

Methotrexate induces production of IL-1 and IL-6 in the monocytic cell line U937

Introduction

Methotrexate (MTX) has been for decades a standard treatment in a wide range of conditions, from malignancies to rheumatoid arthritis (RA). Despite this long experience, the mechanisms of action of MTX remain incompletely understood. Reported immunologic effects of MTX include induction of increased production of some cytokines, an effect that seems to be at odds with the generally anti-inflammatory effects of this drug in diseases like RA. To further elucidate these immune activities, we examined effects of MTX on the human monocytic cell line U937.

Methods

The U937 cell line was treated in vitro with pharmacologic-range concentrations of MTX and effects on production of interleukin (IL)-1, IL-6 and TNF alpha were measured. Changes in gene expression for IL-1 and IL-6 and specificities in the Jun-N-terminal kinase (JNK) signaling pathway including JNK 1, JNK2, JUN and FOS were also determined. The contribution of NF-kB, folate and adenosine pathways to the observed effects was determined by adding appropriate inhibitors to the MTX cultures.

Results

MTX mediated a dose-dependent increase in IL-1 and IL-6 in U937 cells, as measured by secreted proteins and levels of gene expression. The increased cytokine expression was inhibited by addition of parthenolide and folinic acid, but not by caffeine and theophylline, suggesting that NF-kB and folates, but not adenosine, were involved in mediating the observed effects. When U937 cells were cultured with MTX, upregulated expression of JUN and FOS, but not JNK 1 or 2, also was observed.

Conclusions

MTX induces expression of proinflammatory cytokines in U937 monocytic cells. These effects might mediate the known toxicities of MTX including pneumonitis, mucositis and decreased bone mineral density.

TLR4/PKC-mediated tight junction modulation: a clinical marker of chemotherapy-induced gut toxicity?

Chemotherapy-induced gut toxicity is a major clinical and economic burden to oncology practice. The mechanisms responsible for its development are ill defined, hampering the development of therapeutic interventions. In light of newly published research foci and clinical practice guidelines in supportive care in cancer, there has been renewed interest in the role tight junctions play in the pathobiology of chemotherapy-induced gut toxicity. Several preclinical studies have identified molecular defects in intestinal tight junctions following chemotherapy. Despite these findings, the mechanisms responsible for chemotherapy-induced tight junction disruption remain unclear. Recent research has highlighted roles for toll-like receptor 4 and protein kinase C signalling in the regulation of tight junctions. This critical review therefore aims to provide evidence linking toll-like receptor 4 expression, protein kinase C activation and tight junction disruption and their relationship to clinical toxicity.

Mitochondrial dysfunction and respiratory chain defects in a rodent model of methotrexate-induced enteritis

The efficacy of methotrexate (MTX), a widely used chemotherapeutic drug, is limited by its gastrointestinal toxicity and the mechanism of which is not clear. The present study investigates the possible role of mitochondrial damage in MTX-induced enteritis. Small intestinal injury was induced in Wistar rats by the administration of 7 mg kg(-1) body wt. MTX intraperitoneally for 3 consecutive days. MTX administration resulted in severe small intestinal injury and extensive damage to enterocyte mitochondria. Respiratory control ratio, the single most useful and reliable test of mitochondrial function, and 3-(4,5-dimethylthiazol-2-yll)-2,5-diphenyltetrazolium bromide reduction, a measure of cell viability were significantly reduced in all the fractions of MTX-treated rat enterocytes. A massive decrease (nearly 70%) in the activities of complexes II and IV was also observed. The results of the present study suggest that MTX-induced damage to enterocyte mitochondria may play a critical role in enteritis. MTX-induced alteration in mitochondrial structure may cause its dysfunction and decreases the activities of the electron chain complexes. MTX-induced mitochondrial damage can result in reduced adenosine triphosphate synthesis, thereby interfering with nutrient absorption and enterocyte renewal. This derangement may contribute to malabsorption of nutrients, diarrhea, and weight loss seen in patients on MTX chemotherapy.