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Azathioprine Has a Deleterious Effect on the Bone Health of Mice with DSS-Induced Inflammatory Bowel Disease.

ABSTRACT: Patients with inflammatory bowel disease (IBD) often present poor bone health and are 40% more at risk of bone fracture. Studies have implicated autophagy in IBD pathology and drugs used to treat IBD stimulate autophagy in varying degrees, however, their effect on the skeleton is currently unknown. Here, we have utilised the dextran sulphate sodium (DSS) model of colitis in mice to examine the effects of the thiopurine drug azathioprine on the skeleton. Ten-week-old male mice (n = 6/group) received 3.0% DSS in their drinking water for four days, followed by a 14-day recovery period. Mice were treated with 10 mg/kg/day azathioprine or vehicle control. Histopathological analysis of the colon from DSS mice revealed significant increases in scores for inflammation severity, extent, and crypt damage (p < 0.05). Azathioprine provided partial protection to the colon, as reflected by a lack of significant difference in crypt damage and tissue regeneration with DSS treatment. MicroCT of vehicle-treated DSS mice revealed azathioprine treatment had a significant detrimental effect on the trabecular bone microarchitecture, independent of DSS treatment. Specifically, significant decreases were observed in bone volume/tissue volume (p < 0.01), and trabecular number (p < 0.05), with a concurrent significant increase in trabecular pattern factor (p < 0.01). Immunohistochemical labelling for LC3 revealed azathioprine to induce autophagy in the bone marrow. Together these data suggest that azathioprine treatment may have a deleterious effect on IBD patients who may already be at increased risk of osteoporotic bone fractures and thus will inform on future treatment strategies for patient stratification.

SUBMITTER: Morgan S

PROVIDER: S-EPMC6929096 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Individuals with inflammatory bowel disease (IBD) often present with poor bone health. The development of targeted therapies for this bone loss requires a fuller understanding of the underlying cellular mechanisms. Although bone loss in IBD is multifactorial, the altered sensitivity and secretion of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) in IBD is understood to be a critical contributing mechanism. The expression of suppressor of cytokine signaling 2 (SOCS2), a well-established negative regulator of GH signaling, is stimulated by proinflammatory cytokines. Therefore, it is likely that SOCS2 expression represents a critical mediator through which proinflammatory cytokines inhibit GH/IGF-1 signaling and decrease bone quality in IBD. Using the dextran sodium sulfate (DSS) model of colitis, we reveal that endogenously elevated GH function in the Socs2-/- mouse protects the skeleton from osteopenia. Micro-computed tomography assessment of DSS-treated wild-type (WT) mice revealed a worsened trabecular architecture compared to control mice. Specifically, DSS-treated WT mice had significantly decreased bone volume, trabecular thickness and trabecular number, and a resulting increase in trabecular separation. In comparison, the trabecular bone of Socs2-deficient mice was partially protected from the adverse effects of DSS. The reduction in a number of parameters, including bone volume, was less, and no changes were observed in trabecular thickness or separation. This protected phenotype was unlikely to be a consequence of improved mucosal health in the DSS-treated Socs2-/- mice but rather a result of unregulated GH signaling directly on bone. These studies indicate that the absence of SOCS2 is protective against bone loss typical of IBD. This study also provides an improved understanding of the relative effects of GH/IGF-1 signaling on bone health in experimental colitis, information that is essential before these drugs are explored as bone protective agents in children and adults with IBD.

Project description:Liver disorder often occurs in patients with inflammatory bowel disease (IBD); however, the changes in IBD-induced liver disorder at the intrinsic molecular level (chiefly metabolites) and therapeutic targets are still poorly characterized. First, a refined and translationally relevant model of DSS chronic colitis in C57BL/6 mice was established, and cecropin A and antibiotics were used as interventions. We found that the levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 in the liver tissues of mice were highly increased in the context of DSS treatment but were lowered by cecropin A and antibiotics. Subsequently, an untargeted metabolomics analysis was performed by UPLC-Orbitrap-MS/MS to reveal the metabolic profile and attempt to find the potential therapeutic targets of the liver disorders that occur in IBD. Notably, 133 metabolites were identified by an integrated database. Metabolism network and pathway analyses demonstrated that the metabolic disturbance of the liver in IBD mice was mainly enriched in bile acid metabolism, arachidonic acid metabolism, amino acid metabolism, and steroid hormone biosynthesis, while those disturbances were regulated or reversed through cecropin A and antibiotic treatment. Furthermore, the top 20 metabolites, such as glutathione, maltose, arachidonic acid, and thiamine, were screened as biomarkers via one-way analysis of variance (one-way ANOVA, p < 0.05) coupled with variable importance for project values (VIP >1) of orthogonal partial least-squares discriminant analysis (OPLS-DA), which could be upregulated or downregulated with the cecropin A and antibiotics treatment. Spearman correlation analysis showed that the majority of the biomarkers have a significant correlation with cytokines (TNF-α, IL-1β, IL-6, and IL-10), indicating that those biomarkers may act as potential targets to interact directly or indirectly with cecropin A and antibiotics to affect liver inflammation. Collectively, our results extend the understanding of the molecular alteration of liver disorders occurring in IBD and offer an opportunity for discovering potential therapeutic targets in the IBD process.

Project description:Methylthioadenosine (MTA) is a precursor of the methionine salvage pathway and has been shown to have anti-inflammatory properties in various models of acute and chronic inflammation. However, the anti-inflammatory properties of MTA in models of intestinal inflammation are not defined. We hypothesized that orally administered MTA would be bioavailable and reduce morbidity associated with experimental colitis. We examined clinical, histological, and molecular markers of disease in mice provided oral MTA before (preventative) or after (therapy) the induction of colitis with 3% dextran sulfate sodium (DSS). We found a reduction in disease activity, weight loss, myeloperoxidase activity, and histological damage in mice given preventative MTA compared with DSS alone. We also found that equivalent supplementation with methionine could not reproduce the anti-inflammatory effects of MTA, and that MTA had no detectable adverse effects in control or DSS mice. Expression microarray analysis of colonic tissue showed several dominant pathways related to inflammatory cytokines/chemokines and extracellular matrix remodeling were upregulation by DSS and suppressed in MTA-supplemented mice. MTA is rapidly absorbed in the gastrointestinal tract and disseminated throughout the body, based on a time course analysis of an oral bolus of MTA. This effect is transient, with MTA levels falling to near baseline within 90 min in most organs. Moreover, MTA did not lead to increased blood or tissue methionine levels, suggesting that its effects are specific. However, MTA provided limited therapeutic benefit when administered after the onset of colitis. Our results show that oral MTA supplementation is a safe and effective strategy to prevent inflammation and tissue injury associated with DSS colitis in mice. Additional studies in chronic inflammatory models are necessary to determine if MTA is a safe and beneficial option for the maintenance of remission in human inflammatory bowel disease.

Project description:IntroductionAzathioprine-induced pancreatitis is an idiosyncratic and unpredictable response, occurring in up to 7% of azathioprine-exposed patients with inflammatory bowel disease (IBD). The haplotype HLADQA1-HLADRB1*07:01A>C is strongly associated with azathioprine-induced pancreatitis in IBD. We aimed to evaluate whether pretreatment HLADQA1-HLADRB1*07:01A>C screening will reduce the risk of azathioprine-induced pancreatitis.MethodsParticipants with IBD were screened for HLADQA1-HLADRB1*07:01A>C, and participants with a variant genotype were excluded from azathioprine treatment. Wild-type participants were started on azathioprine and followed for 3 months. The incidence of pancreatitis was compared with unscreened historical controls.ResultsHLADQA1-HLADRB1*07:01A>C screening resulted in an 11-fold reduction in the incidence of azathioprine-induced pancreatitis (n = 1/328 or 0.30% vs n = 13/373 or 3.4%). In propensity score-matched cohorts (age and sex), HLA DQA1-HLADRB1*07:01A>C screening was significantly associated with a reduction in the incidence of AZA-induced pancreatitis independent of weight, glucocorticoid exposure, and smoking status (adjusted odds ratio = 0.075, 95% confidence interval = 0.01-0.58, P = 0.01). Up to 45% (n = 271/599) of participants were excluded from azathioprine therapy based on the haplotype in the HLADQA1-HLADRB1*07:01A>C-screened cohort.DiscussionHLADQA1-HLADRB1*07:01A>C screening reduced the risk of azathioprine-induced pancreatitis; however, using this strategy to guide the use of azathioprine therapy in IBD may eliminate a large proportion of patients from being eligible for treatment with azathioprine. In regions where there is access to other IBD therapies, and given the short-term and long-term toxicities associated with azathioprine, HLADQA1-HLADRB1*07:01A>C-screening may be a clinically relevant strategy for enhancing the safe use of azathioprine in IBD. In addition, cost-effectiveness analyses are needed to further solidify the utility of HLADQA1-HLADRB1*07:01A>C screening in IBD populations.

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Azathioprine Has a Deleterious Effect on the Bone Health of Mice with DSS-Induced Inflammatory Bowel Disease.

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