Ischemic colitis with type I interferons used in the treatment of hepatitis C and multiple sclerosis: an evaluation from the food and drug administration adverse event reporting system and review of the literature

Drug-Induced Colitis

Drug-induced colitis encompasses a wide spectrum of colon disorders that can manifest microscopically or macroscopically. Patients present with new-onset colitis or exacerbations of inflammatory bowel diseases; in some cases, colitis resolves with discontinuation of medication. Mucosal injury can be focal or extensive, involving the entire colonic mucosa, and sometimes involves other parts of the gastrointestinal tract. It has been a challenge to determine the proportion of new-onset colitis caused by medication and there are few data on the overall prevalence. We review the drugs that have been linked with development of drug-induced colitis and strategies for physicians who believe their patients have this disorder-usually discontinuation of the drug believed to cause colitis and treatment with steroids or immune-modulating therapies. Physicians must be aware of medications that can cause colitis.

Stimulator of interferon genes (STING) activation exacerbates experimental colitis in mice

Detection of cytoplasmic DNA by the host’s innate immune system is essential for microbial and endogenous pathogen recognition. In mammalian cells, an important sensor is the stimulator of interferon genes (STING) protein, which upon activation by bacterially-derived cyclic dinucleotides (cDNs) or cytosolic dsDNA (dsDNA), triggers type I interferons and pro-inflammatory cytokine production. Given the abundance of bacterially-derived cDNs in the gut, we determined whether STING deletion, or stimulation, acts to modulate the severity of intestinal inflammation in the dextran sodium sulphate (DSS) model of colitis. DSS was administered to Tmem173^gt (STING-mutant) mice and to wild-type mice co-treated with DSS and a STING agonist. Colitis severity was markedly reduced in the DSS-treated Tmem173^gt mice and greatly exacerbated in wild-type mice co-treated with the STING agonist. STING expression levels were also assessed in colonic tissues, murine bone marrow derived macrophages (BMDMs), and human THP-1 cells. M1 and M2 polarized THP-1 and murine BMDMs were also stimulated with STING agonists and ligands to assess their responses. STING expression was increased in both murine and human M1 polarized macrophages and a STING agonist repolarized M2 macrophages towards an M1-like subtype. Our results suggest that STING is involved in the host’s response to acutely-induced colitis.

Ischemic Colitis as a Complication of Medication Use: An Analysis of the Federal Adverse Event Reporting System

BACKGROUND

More than one decade ago, rising cases of ischemic colitis (IC) prompted the Federal Drug Administration to revoke alosetron's approval as treatment of irritable bowel syndrome (IBS). The aim of this study was to identify medical therapies associated with development of IC.

METHODS

The Federal Adverse Event Reporting System was queried for the time between January 2004 and September 2015. We identified reports listing IC as treatment complication and extracted suspected causative and concomitantly administered drugs, indications for their use and outcomes.

RESULTS

After eliminating duplicates, we found 2811 cases of IC (68.4 % women; 59.4 ± 0.4 years). Patients with IBS accounted for 3.9 % of the cases, mostly attributed to tegaserod or alosetron. Chemotherapeutic and immunosuppressive drugs, sex hormones, and anticoagulants were the most commonly suspected causes. Bisphosphonates, nonsteroidal anti-inflammatory drugs, antipsychotics, triptans, interferon therapy, and laxative use prior to colonoscopy were among the more commonly listed treatments. In 8 %, the adverse event contributed to the patient's death with male sex and older age predicting fatal outcomes.

CONCLUSION

Beyond confirming known risks of IC, the results identified several potential culprits of ischemic colitis. This information may not only explain the development of this serious adverse event, but could also guide treatment decisions, cautioning healthcare providers when considering these agents in persons with known risk factors or other drugs that may increase their risk of IC.

Colon Ischemia: An Update for Clinicians

Colon ischemia (CI) is an underrecognized entity associated with high morbidity and mortality. Establishing the diagnosis and initiating appropriate and timely treatment is critical for improving outcomes. Colon ischemia is a disease spectrum that requires a full understanding for recognition and treatment. This review outlines the full spectrum of CI management from initial presentation to medical and surgical treatment.

Systematic Analysis of Adverse Event Reports for Sex Differences in Adverse Drug Events

Increasing evidence has shown that sex differences exist in Adverse Drug Events (ADEs). Identifying those sex differences in ADEs could reduce the experience of ADEs for patients and could be conducive to the development of personalized medicine. In this study, we analyzed a normalized US Food and Drug Administration Adverse Event Reporting System (FAERS). Chi-squared test was conducted to discover which treatment regimens or drugs had sex differences in adverse events. Moreover, reporting odds ratio (ROR) and P value were calculated to quantify the signals of sex differences for specific drug-event combinations. Logistic regression was applied to remove the confounding effect from the baseline sex difference of the events. We detected among 668 drugs of the most frequent 20 treatment regimens in the United States, 307 drugs have sex differences in ADEs. In addition, we identified 736 unique drug-event combinations with significant sex differences. After removing the confounding effect from the baseline sex difference of the events, there are 266 combinations remained. Drug labels or previous studies verified some of them while others warrant further investigation.

Noncanonical Effects of IRF9 in Intestinal Inflammation: More than Type I and Type III Interferons

The interferon (IFN)-stimulated gene factor 3 (ISGF3) transcription factor with its Stat1, Stat2, and interferon regulatory factor 9 (IRF9) subunits is employed for transcriptional responses downstream of receptors for type I interferons (IFN-I) that include IFN-α and IFN-β and type III interferons (IFN-III), also called IFN-λ. Here, we show in a murine model of dextran sodium sulfate (DSS)-induced colitis that IRF9 deficiency protects animals, whereas the combined loss of IFN-I and IFN-III receptors worsens their condition. We explain the different phenotypes by demonstrating a function of IRF9 in a noncanonical transcriptional complex with Stat1, apart from IFN-I and IFN-III signaling. Together, Stat1 and IRF9 produce a proinflammatory activity that overrides the benefits of the IFN-III response on intestinal epithelial cells. Our results further suggest that the CXCL10 chemokine gene is an important mediator of this proinflammatory activity. We thus establish IFN-λ as a potentially anticolitogenic cytokine and propose an important role for IRF9 as a component of noncanonical Stat complexes in the development of colitis.

Type I interferons have opposing effects during the emergence and recovery phases of colitis

The contribution of the innate immune system to inflammatory bowel disease (IBD) is under intensive investigation. Research in animal models has demonstrated that type I interferons (IFN-Is) protect from IBD. In contrast, studies of patients with IBD have produced conflicting results concerning the therapeutic potential of IFN-Is. Here, we present data suggesting that IFN-Is play dual roles as regulators of intestinal inflammation in dextran sodium sulfate (DSS)-treated C57BL/6 mice. Though IFN-Is reduced acute intestinal damage and the abundance of colitis-associated intestinal bacteria caused by treatment with a high dose of DSS, they also inhibited the resolution of inflammation after DSS treatment. IFN-Is played an anti-inflammatory role by suppressing the release of IL-1β from the colon MHC class II(+) cells. Consistently, IL-1 receptor blockade reduced the severity of inflammation in IFN-I receptor-deficient mice and myeloid cell-restricted ablation of the IFN-I receptor was detrimental. The proinflammatory role of IFN-Is during recovery from DSS treatment was caused by IFN-I-dependent cell apoptosis as well as an increase in chemokine production and infiltrating inflammatory monocytes and neutrophils. Thus, IFN-Is play opposing roles in specific phases of intestinal injury and inflammation, which may be important for guiding treatment strategies in patients.

The colon: from banal to brilliant

The colon serves as the habitat for trillions of microbes, which it must maintain, regulate, and sequester. This is managed by what is termed the mucosal barrier. The mucosal barrier separates the gut flora from the host tissues; regulates the absorption of water, electrolytes, minerals, and vitamins; and facilitates host-flora interactions. Colonic homeostasis depends on a complex interaction between the microflora and the mucosal epithelium, immune system, vasculature, stroma, and nervous system. Disruptions in the colonic microenvironment such as changes in microbial composition, epithelial cell function/proliferation/differentiation, mucus production/makeup, immune function, diet, motility, or blood flow may have substantial local and systemic consequences. Understanding the complex activities of the colon in health and disease is important in drug development, as xenobiotics can impact all segments of the colon. Direct and indirect effects of pharmaceuticals on intestinal function can produce adverse findings in laboratory animals and humans and can negatively impact drug development. This review will discuss normal colon homeostasis with examples, where applicable, of xenobiotics that disrupt normal function.