Darunavir alleviates irinotecan-induced intestinal toxicity in Vivo

Mechanisms and emerging strategies for irinotecan-induced diarrhea

Irinotecan (also known as CPT-11) is a topoisomerase I inhibitor first approved for clinical use as an anticancer agent in 1996. Over the past more than two decades, it has been widely used for combination regimens to treat various malignancies, especially in gastrointestinal and lung cancers. However, severe dose-limiting toxicities, especially gastrointestinal toxicity such as late-onset diarrhea, were frequently observed in irinotecan-based therapy, thus largely limiting the clinical application of this agent. Current knowledge regarding the pathogenesis of irinotecan-induced diarrhea is characterized by the complicated metabolism of irinotecan to its active metabolite SN-38 and inactive metabolite SN-38G. A series of enzymes and transporters were involved in these metabolic processes, including UGT1A1 and CYP3A4. Genetic polymorphisms of these metabolizing enzymes were significantly associated with the occurrence of irinotecan-induced diarrhea. Recent discoveries and progress made on the detailed mechanisms enable the identification of potential biomarkers for predicting diarrhea and as such guiding the proper patient selection with a better range of tolerant dosages. In this review, we introduce the metabolic process of irinotecan and describe the pathogenic mechanisms underlying irinotecan-induced diarrhea. Based on the mechanisms, we further outline the potential biomarkers for predicting the severity of diarrhea. Finally, based on the current experimental evidence in preclinical and clinical studies, we discuss and prospect the current and emerging strategies for the prevention of irinotecan-induced diarrhea.

Discovery of novel carboxylesterase 2 inhibitors for the treatment of delayed diarrhea and ulcerative colitis

Human carboxylesterase 2 (hCES2) is an enzyme that metabolizes irinotecan to SN-38, a toxic metabolite considered a significant source of side effects (lethal delayed diarrhea). The hCES2 inhibitors could block the hydrolysis of irinotecan in the intestine and thus reduce the exposure of intestinal SN-38, which may alleviate irinotecan-associated diarrhea. However, existing hCES2 inhibitors (except loperamide) are not used in clinical applications due to lack of validity or acceptable safety. Therefore, developing more effective and safer drugs for treating delayed diarrhea is urgently needed. This study identified a lead compound 1 with a novel scaffold by high-throughput screening in our in-house library. After a comprehensive structure-activity relationship study, the optimal compound 24 was discovered as an efficient and highly selective hCES2 inhibitor (hCES2: IC50 = 6.72 μM; hCES1: IC50 > 100 μM). Further enzyme kinetics study indicated that compound 24 is a reversible inhibitor of hCES2 with competitive inhibition mode (Ki = 6.28 μM). The cell experiments showed that compound 24 could reduce the level of hCES2 in living cells (IC50 = 6.54 μM). The modeling study suggested that compound 24 fitted very well with the binding pocket of hCES2 by forming multiple interactions. Notably, compound 24 can effectively treat irinotecan-induced delayed diarrhea and DSS-induced ulcerative colitis, and its safety has also been verified in subtoxic studies. Based on the overall pharmacological and preliminary safety profiles, compound 24 is worthy of further evaluation as a novel agent for irinotecan-induced delayed diarrhea.

Investigation of the Possible Protective Effect of N-Acetylcysteine (NAC) against Irinotecan (CPT-11)-Induced Toxicity in Rats

Irinotecan (CPT-11) is a chemotherapeutic agent involved in the treatment regimens for several malignancies such as colorectal cancer. N-acetylcysteine (NAC) is a strong antioxidant and anti-inflammatory agent used in the treatment of several diseases related to oxidative stress and inflammation. This study aimed at investigating whether NAC provides protection against hepatorenal and gastrointestinal tissue damage induced by CPT-11. Thirty-two Wistar albino rats were divided into four groups as control, NAC, CPT-11, and CPT-11+NAC. Following the experimental period, blood, and tissue samples (liver, kidney, stomach, and small intestine) were collected, and biochemical indicators, together with pro-inflammatory cytokines (TNF-α and IL-1β), matrix metalloproteinases (MMPs), malondialdehyde (MDA), glutathione peroxidase (GPx) and superoxide dismutase (SOD) levels were evaluated. Both the biochemical indicators and the pro-inflammatory cytokines, MMP, and MDA levels increased in animals treated with CPT-11, while SOD and GPx activities decreased. Histopathological evaluation revealed structural damage in all examined tissues. With NAC administration, significant improvements were observed, both biochemically and histologically. In conclusion, the results of the present study suggest that NAC treatment together with CPT-11 may have a beneficial effect on reducing CPT-11 toxicity in rats, by modulating inflammation and the oxidant-antioxidant balance. These results strongly promote further investigative studies.

Selenium-enriched Bifidobacterium longum DD98 attenuates irinotecan-induced intestinal and hepatic toxicity in vitro and in vivo

Irinotecan (CPT-11) is a camptothecin chemotherapy drug largely used in treating cancers. However, its strong adverse effects, such as gastrointestinal and hepatic toxicities, tend to reduce the patients' life qualities and to limit the clinical use of CPT-11. The protective roles of selenium (Se) and probiotics against CPT-11-induced toxicity have been widely reported. However, the application of Se-enriched probiotics in the adjuvant therapy of CPT-11 has not been well explored. The purpose of this study is to evaluate the in-vitro and in-vivo effects of Se-enriched Bifidobacterium longum DD98 (Se-B. longum DD98) as a chemotherapy preventive agent on alleviating intestinal and hepatic toxicities induced by CPT-11 chemotherapy. The results showed that Se-B. longum DD98 positively regulated the aberrant cell viability and oxidative stress induced by CPT-11 both in human normal liver (L-02) and rat small intestinal epithelial (IEC-6) cell lines. In vivo experiment revealed that Se-B. longum DD98 significantly attenuated intestinal and hepatic toxicities by ameliorating symptoms such as body weight loss and diarrhea, and by improving the biochemical indicators of hepatotoxicity and oxidative stress. Furthermore, we discovered that the protective effects of Se-B. longum DD98 based largely upon decreasing the pro-inflammatory cytokines IL-1β and IL-18 and enhancing the expression of tight-junction proteins occludin and ZO-1, as well as restoring the composition and diversity of gut microbiota. Results suggested that Se-B. longum DD98 effectively protected livers and intestines against the CPT-11-induced damages, and therefore, could be considered as a promising adjuvant therapeutic agent with CPT-11 for the cancer treatment.

Involvement of SIRT1 in amelioration of schistosomiasis-induced hepatic fibrosis by genistein

Previous study revealed that genistein alleviate the extent of hepatic fibrosis in schistosomiasis-infected mice, however, the potential mechanism is still incomplete. Present study was, therefore, carried out to investigate the underlying mechanism of ameliorating schistosomiasis-induced hepatic fibrosis by genistein. α-smooth muscle actin (α-SMA) expression, as a critical fibrotic marker, was markedly upregulated in Schistosoma japonicum (S. japonicum) egg-induced liver fibrosis, and gradually inhibited by genistein administration in infected mice. Contrary to the changes of α-SMA expression, hepatic SIRT1 expression and activity was greatly inhibited in mice upon S. japonicum infection, and the repression was reversed in liver tissues after receiving 25 mg/kg genistein. 50 mg/kg genistein treatment gave rise to the higher SIRT1 expression and activity than that of the control group. In hepatic stellate cells (HSCs), genistein (5, 10, 20 μM) treatment resulted in the increases of SIRT1 expression and activity in concentration-dependent manner. Moreover, to mimic the fibrogenesis in vivo, macrophage was treated with soluble egg antigen (SEA) to obtain macrophage-conditioned medium (MφCM), which was used to stimulate HSCs. Intriguingly, SIRT1 overexpression decreased fibrosis associated gene expression in HSCs exposed to MφCM or not. Additionally, MφCM gave rise to high levels of α-SMA and p-Smad3 and the increments were reversed upon genistein treatment in HSCs. Furthermore, EX527, SIRT1 specific inhibitor, abrogated the inhibitory effects of genistein on HSCs activation. Together, the results support the notion that the strong elevation of SIRT1 expression and activity may represent a potential mechanism of protection against schistosomiasis-induced hepatic fibrosis by genistein.

Tryptophan Pathway-Targeted Metabolomics Study on the Mechanism and Intervention of Cisplatin-Induced Acute Kidney Injury in Rats

Cisplatin is a chemotherapeutic agent widely employed in the treatment of various solid tumors. However, its use is often restricted by acute kidney injury (AKI) which is the dose-limiting adverse effect of cisplatin. While numerous studies aiming to alleviate the AKI have been conducted, there are no effective remedies in clinical practice. In this paper, a targeted metabolomics study was performed to reveal the potential relationship between tryptophan metabolism and cisplatin-induced AKI. A chemical derivatization integrated liquid chromatography coupled tandem mass spectrometry (LC-MS/MS) approach was utilized to quantify 29 metabolites in the tryptophan pathway in rat kidney medulla and cortex after cisplatin administration. Results showed that tryptophan metabolism was remarkably disturbed both in the medulla and cortex after cisplatin administration. We also found that the tryptophan pathway in the medulla was more sensitive to cisplatin exposure compared with the cortex. Among these metabolites, indoxyl sulfate was focused for further study because it accumulated most significantly in the kidney cortex and medulla in a dose-dependent manner. A function verification study proved that chlormethiazole, a widely used CYP2E1 inhibitor, could reduce the production of indoxyl sulfate in the liver and attenuate cisplatin-induced AKI in rats. In conclusion, our study depicted the tryptophan pathway in cisplatin-induced AKI for the first time and demonstrated tryptophan metabolism is closely associated with the renal toxicity caused by cisplatin, which can be of great use for the discovery of renal toxicity attenuating remedies.

Entropy-driven binding of gut bacterial β-glucuronidase inhibitors ameliorates irinotecan-induced toxicity

Irinotecan inhibits cell proliferation and thus is used for the primary treatment of colorectal cancer. Metabolism of irinotecan involves incorporation of β-glucuronic acid to facilitate excretion. During transit of the glucuronidated product through the gastrointestinal tract, an induced upregulation of gut microbial β-glucuronidase (GUS) activity may cause severe diarrhea and thus force many patients to stop treatment. We herein report the development of uronic isofagomine (UIFG) derivatives that act as general, potent inhibitors of bacterial GUSs, especially those of Escherichia coli and Clostridium perfringens. The best inhibitor, C6-nonyl UIFG, is 23,300-fold more selective for E. coli GUS than for human GUS (Ki = 0.0045 and 105 μM, respectively). Structural evidence indicated that the loss of coordinated water molecules, with the consequent increase in entropy, contributes to the high affinity and selectivity for bacterial GUSs. The inhibitors also effectively reduced irinotecan-induced diarrhea in mice without damaging intestinal epithelial cells.

The hidden role of NLRP3 inflammasome in obesity-related COVID-19 exacerbations: Lessons for drug repurposing

COVID-19, the illness caused by SARS-CoV-2, has a wide-ranging clinical spectrum that, in the worst-case scenario, involves a rapid progression to severe acute respiratory syndrome and death. Epidemiological data show that obesity and diabetes are among the main risk factors associated with high morbidity and mortality. The increased susceptibility to SARS-CoV-2 infection documented in obesity-related metabolic derangements argues for initial defects in defence mechanisms, most likely due to an elevated systemic metabolic inflammation ("metaflammation"). The NLRP3 inflammasome is a master regulator of metaflammation and has a pivotal role in the pathophysiology of either obesity or diabetes. Here, we discuss the most recent findings suggesting contribution of NLRP3 inflammasome to the increase in complications in COVID-19 patients with diabesity. We also review current pharmacological strategies for COVID-19, focusing on treatments whose efficacy could be due, at least in part, to interference with the activation of the NLRP3 inflammasome. LINKED ARTICLES: This article is part of a themed issue on The Pharmacology of COVID-19. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.21/issuetoc.

Genistein protects against acetaminophen-induced liver toxicity through augmentation of SIRT1 with induction of Nrf2 signalling

Previous studies suggest that genistein protects liver from acetaminophen (APAP)-induced injury, however, the detailed mechanism of the process is still incompletely. Therefore, present study was to investigate the potential mechanism of the genistein mediated protection against APAP-induced hepatotoxicity. As shown, supplementation with 150 mg/kg genistein greatly alleviated the increase in serum alanine aminotransferase (ALT) activity, aspartate aminotransferase (AST) activity, hepatic malondialdehyde (MDA) contents, and reversed the decrease in hepatic GSH levels in response to overdose APAP. At the same time, hepatic SIRT1 protein and activity were markedly upregulated in mouse receiving genistein. However, the amelioration was almost abolished by the knockdown of hepatic SIRT1 expression using lentivirus carrying specific shRNA targeting SIRT1. These results were further validated by histopathology examination. Moreover, depletion of hepatic SIRT1 prevented the accumulation of Nrf2 in nucleus and the upregulation of the antioxidant gene expression in the presence of genistein and/or APAP. Concomitantly, the induced mRNA expression of UDP-glucuronosyltransferases (UGTs) by genistein was largely dependent on the SIRT1 expression and activity. Together, our results support the notion that the strong elevation of SIRT1 expression and activity may represent a potential mechanism of protection against APAP-induced liver injury by genistein.

Irinotecan: 25 years of cancer treatment

Twenty-five years ago, the cytotoxic drug irinotecan (IRT) was first approved in Japan for the treatment of cancer. For more than two decades, the IRT prodrug has largely contributed to the treatment of solid tumors worldwide. Nowadays, this camptothecin derivative targeting topoisomerase 1 remains largely used in combination regimen, like FOLFIRI and FOLFIRINOX, to treat metastatic or advanced solid tumors, such as colon, gastric and pancreatic cancers and others. This review highlights recent discoveries in the field of IRT and its derivatives, including analogues of the active metabolite SN38 (such as FL118), the recently approved liposomal form Nal-IRI and SN38-based immuno-conjugates currently in development (such as sacituzumab govitecan). New information about the IRT mechanism of action are presented, including the discovery of a new protein target, the single-stranded DNA-binding protein FUBP1. Significant progress has been made also to better understand and manage the main limiting toxicities of IRT, chiefly neutropenia and diarrhea. The role of drug-induced inflammation and dysbiosis is underlined and strategies to limit the intestinal toxicity of IRT are discussed (use of β-glucuronidase inhibitors, plant extracts, probiotics). The detailed knowledge of the metabolism of IRT has enabled the identification of potential biomarkers to guide patient selection and to limit drug-induced toxicities, but no robust IRT-specific therapeutic biomarker has been approved yet. IRT is a versatile chemotherapeutic agent which combines well with a variety of anticancer drugs. It offers a large range of drug combinations with cytotoxic agents, targeted products and immuno-active biotherapeutics, to treat a variety of advanced solid carcinoma, sarcoma and cancers with progressive central nervous system diseases. A quarter of century after its first launch, IRT remains an essential anticancer drug, largely prescribed, useful to many patients and scientifically inspiring.

Traditional Chinese medicine Gegen Qinlian decoction ameliorates irinotecan chemotherapy-induced gut toxicity in mice

BACKGROUND

Gegen Qinlian decoction (GQT), is a classic traditional Chinese medicine formula chronicled in Shang Han Lun, and is widely used to treat diarrhea and inflammation symptoms in various gastrointestinal disorders. Although it has been found to inhibit delayed-onset mice diarrhea resulted from irinotecan (CPT-11) administration in preliminary experiments, the underlying mechanisms and chemical components remain elusive.

METHODS

The effective fraction of GQT by macroporous resin elution was obtained and screened using a diarrhea mouse model induced by CPT-11 and quantified by UPLC analysis. The protective effect of GQT extract towards alleviating diarrhea in mice following CPT-11 administration was further investigated. The levels of inflammatory cytokines and intestinal tight junction related proteins in colonic tissues were determined. The inhibitory effect of GQT extract against hCE2 was evaluated by a fluorescence-based method. Lastly, the synergistic effect of GQT extract combined with CPT-11 against tumor growth in a colorectal tumor mouse model, induced by HT-29 colon cancer cells xenograft subcutaneously, was investigated.

RESULTS

The obtained GQT extract, which profoundly ameliorated the gut toxicity induced by CPT-11, contained puerarin, liquiritin, berberine, and baicalin of 27.2 mg/g, 4.6 mg/g, 491.4 mg/g, and 304.2 mg/g, respectively. After 5 days of administration of GQT extract to mice with diarrhea induced by CPT-11, aberrantly elevated levels of pro-inflammatory cytokines, including IL-1β, COX-2, ICAM-1, and TNF-α, were significantly decreased. Meanwhile, GQT extract also exhibited a remarkable anti-oxidative stress effect, involving activating the Keap1/Nrf2 pathway, and up-regulating the intestinal barrier function by enhancing the expression of tight junction proteins ZO-1, HO-1, and occludin. Additionally, a potent inhibitory effect of GQT extract against hCE2 was observedin vitro, with its IC₅₀ value of 0.187 mg/ml, suggesting alleviating activity on hCE2-mediated severe diarrhea in patients suffered from CPT-11. Moreover, GQT extract was shown to improve inhibition of the colonic tumor growth synergistically with CPT-11.

CONCLUSION

The present study indicates that GQT extract can ameliorate CPT-11 induced gut toxicity in mice and improve CPT-11 efficacy in colorectal cancer treatment.