Iron status, anemia, and plasma erythropoietin levels in acute and chronic mouse models of colitis

Silicone cryogel skeletons enhance the survival and mechanical integrity of hydrogel-encapsulated cell therapies

The transplantation of engineered cells that secrete therapeutic proteins presents a promising method for addressing a range of chronic diseases. However, hydrogels used to encase and protect non-autologous cells from immune rejection often suffer from poor mechanical properties, insufficient oxygenation, and fibrotic encapsulation. Here, we introduce a composite encapsulation system comprising an oxygen-permeable silicone cryogel skeleton, a hydrogel matrix, and a fibrosis-resistant polymer coating. Cryogel skeletons enhance the fracture toughness of conventional alginate hydrogels by 23-fold and oxygen diffusion by 2.8-fold, effectively mitigating both implant fracture and hypoxia of encapsulated cells. Composite implants containing xenogeneic cells engineered to secrete erythropoietin significantly outperform unsupported alginate implants in therapeutic delivery over 8 weeks in immunocompetent mice. By improving mechanical resiliency and sustaining denser cell populations, silicone cryogel skeletons enable more durable and miniaturized therapeutic implants.

P2X1 ion channel deficiency causes massive bleeding in inflamed intestine and increases thrombosis

BACKGROUND

Intestinal inflammation is associated with bleeding and thrombosis, two processes that may involve both platelets and neutrophils. However, the mechanisms and the respective contribution of these cells to intestinal bleeding and extra-intestinal thrombosis remain largely unknown.

OBJECTIVE

Our study aimed at investigating the mechanisms underlying the maintenance of vascular integrity and thrombosis in intestinal inflammation.

METHODS

We used a mouse model of acute colitis induced by oral administration of dextran sodium sulfate (DSS) for 7 days. Bleeding was assessed after depletion of platelets, neutrophils, or glycoprotein VI (GPVI); treatment with aspirin or clopidogrel; or in P2X1-deficient mice. Extra-intestinal thrombosis was analyzed using a laser-induced injury model of thrombosis in cremaster muscle arterioles.

RESULTS

Platelet depletion or P2X1 deficiency led to macrocytic regenerative anemia due to intestinal hemorrhage. In contrast, GPVI, P2Y12, and thromboxane A2 were dispensable. Platelet P-selectin expression and regulated on activation, normal T-cell expressed and secreted (RANTES) plasma levels were lower in DSS-treated P2X1-deficient mice as compared to wild-type mice, indicative of a platelet secretion defect. Circulating neutrophils had a more activated phenotype, and neutrophil infiltration in the colon was increased. P2X1-deficient mice also had elevated plasma granulocyte-colony stimulating factor (G-CSF) levels. Neutrophil depletion limited blood loss in these mice, whereas exogenous administration of G-CSF in colitic wild-type mice caused macrocytic anemia. Anemic colitic P2X1-deficient mice formed atypical neutrophil- and fibrin-rich, and platelet-poor thrombi upon arteriolar endothelial injury.

CONCLUSIONS

Platelets and P2X1 ion channels are mandatory to preserve vascular integrity in inflamed intestine. Upon P2X1 deficiency, neutrophils contribute to bleeding and they may also be responsible for enhanced thrombosis.

Autophagy induction by rapamycin ameliorates experimental colitis and improves intestinal epithelial barrier function in IL-10 knockout mice

BACKGROUND

An impairment of the intestinal barrier function is one of the major characteristics of Crohn's disease (CD). This study aimed to evaluate the impact of autophagy induction by rapamycin on the intestinal epithelial barrier function in CD model mice.

METHODS

IL-10 knockout (IL-10 KO) mice were used as the human CD models in this study. All the mice were randomly assigned into four groups, (a) wild-type (WT) group; (b) IL-10 KO group; (c) IL-10 KO + rapamycin group and (d) IL-10 KO + 3-methyladenine (3-MA), containing 6 mice in each group. The disease activity index (DAI), histology, pro-inflammatory cytokines and chemotactic factors in colon tissues, intestinal and colonic permeability, distributions and expressions of tight junction (TJ) proteins, epithelial apoptosis of mice in four groups were evaluated and compared.

RESULTS

Autophagy induction by rapamycin treatment ameliorated DAI and histological colitis, decreased pro-inflammatory cytokines (TNF-α, IFN-γ and IL-17) and chemotactic factors (CXCL-1 and CXCL-2), decreased intestinal and colonic permeability, improved the distribution and expression of TJ proteins in IL-10 KO mice.

CONCLUSION

Autophagy induction by rapamycin significantly improved intestinal barrier function and protected IL-10 KO mice from the experimental chronic colitis.

Management of Iron Deficiency Anaemia in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a group of chronic relapsing inflammatory disorders affecting the large and small intestine, with a rising worldwide incidence and prevalence. Anaemia is the most common extraintestinal manifestation of IBD, correlating with disease activity, and tending to relapse even after successful therapy. Iron deficiency is the most common cause; however, it often manifests in combination with anaemia of inflammation. As such, multiple parameters are used for the diagnosis of iron deficiency anaemia in IBD. Timely recognition and selection of appropriate therapy leads to an improvement in the quality of life and prevention of potential sequelae. Oral iron can be effective under specific circumstances; however, as luminal iron changes microbiota and bacterial metabolism, oral administration should be avoided. Intravenous iron is preferred as it bypasses the sites of inflammation. Nevertheless, the optimization of IBD treatment should occur simultaneously, as this improves both patient condition and response to iron therapy. Herein, we discuss the screening, diagnosis, selection of therapy, and follow-up for iron deficiency anaemia in IBD.

Risk factors for poor outcome in community-onset Clostridium difficile infection

Background

A substantial portion of Clostridium difficile infection (CDI) cases occur in communities, and community-onset CDI (CO-CDI) can lead to serious complications including mortality. This study aimed to identify the risk factors for a poor outcome in CO-CDI.

Methods

We performed a retrospective review of all inpatients with CDI, in a 1300-bed tertiary-care hospital in Korea, from 2008 through 2015. CO-CDI was defined as CDI occurring within 48 h of admission. Poor outcome was defined as follows: 1) all-cause 30-day mortality, 2) in-hospital mortality, or 3) surgery due to CDI.

Results

Of a total 1256 CDIs occurring over 8 years, 152 (12.1%) cases were classified as CO-CDI and 23 (15.1%) had a poor outcome, including 22 (14.5%) cases of mortality and 2 (1.3%) cases of surgery. Patients with a poor outcome had a higher mean age than those without a poor outcome (75.8 vs. 69.6 years, p = 0.03). The proportion of men and prior proton pump inhibitor (PPI) use were significantly higher in the poor outcome group (65.2% vs. 41.9%, p = 0.04; 39.1% vs. 17.6%, p = 0.02, respectively). Multivariate binary logistic model showed that PPI use and anemia (hemoglobin < 10 g/dL) at presentation were significantly associated with a poor outcome (adjusted odds ratio [aOR], 3.76; 95% confidence interval [95CI], 1.26-11.21, aOR, 4.67; 95CI, 1.52-14.34, respectively).

Conclusions

Clinicians should not only be aware of the possibility of CDI in the community setting but also pay more attention to PPI-using elderly patients with anemia in consideration of a poor outcome.

Red Blood Cell Function and Dysfunction: Redox Regulation, Nitric Oxide Metabolism, Anemia

SIGNIFICANCE

Recent clinical evidence identified anemia to be correlated with severe complications of cardiovascular disease (CVD) such as bleeding, thromboembolic events, stroke, hypertension, arrhythmias, and inflammation, particularly in elderly patients. The underlying mechanisms of these complications are largely unidentified. Recent Advances: Previously, red blood cells (RBCs) were considered exclusively as transporters of oxygen and nutrients to the tissues. More recent experimental evidence indicates that RBCs are important interorgan communication systems with additional functions, including participation in control of systemic nitric oxide metabolism, redox regulation, blood rheology, and viscosity. In this article, we aim to revise and discuss the potential impact of these noncanonical functions of RBCs and their dysfunction in the cardiovascular system and in anemia.

CRITICAL ISSUES

The mechanistic links between changes of RBC functional properties and cardiovascular complications related to anemia have not been untangled so far.

FUTURE DIRECTIONS

To allow a better understanding of the complications associated with anemia in CVD, basic and translational science studies should be focused on identifying the role of noncanonical functions of RBCs in the cardiovascular system and on defining intrinsic and/or systemic dysfunction of RBCs in anemia and its relationship to CVD both in animal models and clinical settings. Antioxid. Redox Signal. 26, 718-742.

Helicobacter pylori Infection Induces Anemia, Depletes Serum Iron Storage, and Alters Local Iron-Related and Adult Brain Gene Expression in Male INS-GAS Mice

Iron deficiency anemia (IDA) affects > 500 million people worldwide, and is linked to impaired cognitive development and function in children. Helicobacter pylori, a class 1 carcinogen, infects about half of the world’s population, thus creating a high likelihood of overlapping risk. This study determined the effect of H. pylori infection on iron homeostasis in INS-GAS mice. Two replicates of INS-GAS/FVB male mice (n = 9-12/group) were dosed with H. pylori (Hp) strain SS1 or sham dosed at 6–9 weeks of age, and were necropsied at 27–29 weeks of age. Hematologic and serum iron parameters were evaluated, as was gene expression in gastric and brain tissues. Serum ferritin was lower in Hp SS1-infected mice than uninfected mice (p < 0.0001). Infected mice had a lower red blood cell count (p<0.0001), hematocrit (p < 0.001), and hemoglobin concentration (p <0.0001) than uninfected mice. Relative expression of gastric hepcidin antimicrobial peptide (Hamp) was downregulated in mice infected with Hp SS1 compared to sham-dosed controls (p<0.001). Expression of bone morphogenic protein 4 (Bmp4), a growth factor upstream of hepcidin, was downregulated in gastric tissue of Hp SS1-infected mice (p<0.001). Hp SS1-infected mice had downregulated brain expression of tyrosine hydroxylase (Th) (p = 0.02). Expression of iron-responsive genes involved in myelination (myelin basic protein (Mbp) and proteolipid protein 2 (Plp2)) was downregulated in infected mice (p = 0.001 and p = 0.02). Expression of synaptic plasticity markers (brain derived neurotrophic factor 3 (Bdnf3), Psd95 (a membrane associated guanylate kinase), and insulin-like growth factor 1 (Igf1)) was also downregulated in Hp SS1-infected mice (p = 0.09, p = 0.04, p = 0.02 respectively). Infection of male INS-GAS mice with Hp SS1, without concurrent dietary iron deficiency, depleted serum ferritin, deregulated gastric and hepatic expression of iron regulatory genes, and altered iron-dependent neural processes. The use of Hp SS1-infected INS-GAS mice will be an appropriate animal model for further study of the effects of concurrent H. pylori infection and anemia on iron homeostasis and adult iron-dependent brain gene expression.

DHA protects against experimental colitis in IL-10-deficient mice associated with the modulation of intestinal epithelial barrier function

A defect in the intestinal barrier is one of the characteristics of Crohn's disease (CD). The tight junction (TJ) changes and death of epithelial cells caused by intestinal inflammation play an important role in the development of CD. DHA, a long-chain PUFA, has been shown to be helpful in treating inflammatory bowel disease in experimental models by inhibiting the NF-κB pathway. The present study aimed at investigating the specific effect of DHA on the intestinal barrier function in IL-10-deficient mice. IL-10-deficient mice (IL-10(-/-)) at 16 weeks of age with established colitis were treated with DHA (i.g. 35.5 mg/kg per d) for 2 weeks. The severity of their colitis, levels of pro-inflammatory cytokines, epithelial gene expression, the distributions of TJ proteins (occludin and zona occludens (ZO)-1), and epithelial apoptosis in the proximal colon were measured at the end of the experiment. DHA treatment attenuated the established colitis and was associated with reduced infiltration of inflammatory cells in the colonic mucosa, lower mean histological scores and decreased levels of pro-inflammatory cytokines (IL-17, TNF-α and interferon-γ). Moreover, enhanced barrier function was observed in the DHA-treated mice that resulted from attenuated colonic permeability, rescued expression and corrected distributions of occludin and ZO-1. The results of the present study indicate that DHA therapy may ameliorate experimental colitis in IL-10(-/-) mice by improving the intestinal epithelial barrier function.

Chronic restraint stress after injury and shock is associated with persistent anemia despite prolonged elevation in erythropoietin levels

BACKGROUND

Following severe traumatic injury, critically ill patients have a prolonged hypercatacholamine state that is associated with bone marrow (BM) dysfunction and persistent anemia. However, current animal models of injury and shock result in a transient anemia. Daily restraint stress (chronic stress [CS]) has been shown to increase catecholamines. We hypothesize that adding CS following injury or injury and shock in rats will prolong the hypercatecholaminemia and prolong the initial anemia, despite elevated erythropoietin (EPO) levels.

METHODS

Male Sprague-Dawley rats (n = 6-8 per group) underwent lung contusion (LC) or combined LC/hemorrhagic shock (LCHS) followed by 6 days of CS. CS consisted of a 2-hour restraint period interrupted with repositioning and alarms every 30 minutes. At 7 days, urine was assessed for norepinephrine (NE) levels, blood for EPO and hemoglobin (Hgb), and BM for erythroid progenitor growth.

RESULTS

Animals undergoing LC or combined LCHS predictably recovered by Day 7; urine NE, EPO, and Hgb levels were normal. The addition of CS to LC and LCHS models was associated with a significant elevation in NE on Day 6. The addition of CS to LC led to a persistent 20% to 25% decrease in the growth of BM hematopoietic progenitor cells. These findings were further exaggerated when CS was added following LCHS, resulting in a 20%q to 40% reduction in BM erythroid progenitor colony growth and a 20% decrease in Hgb when compared with LCHS alone.

CONCLUSION

Exposing injured animals to CS results in prolonged elevation of NE and EPO, which is associated with worsening BM erythroid function and persistent anemia. Chronic restraint stress following injury and shock provides a clinically relevant model to further evaluate persistent injury-associated anemia seen in critically ill trauma patients. Furthermore, alleviating CS after severe injury is a potential therapeutic target to improve BM dysfunction and anemia.

Anti-mouse CD52 monoclonal antibody ameliorates intestinal epithelial barrier function in interleukin-10 knockout mice with spontaneous chronic colitis

Intestinal inflammation causes tight junction changes and death of epithelial cells, and plays an important role in the development of Crohn's disease (CD). CD52 monoclonal antibody (CD52 mAb) directly targets the cell surface CD52 and is effective in depleting mature lymphocytes by cytolytic effects in vivo, leading to long-lasting changes in adaptive immunity. The aim of this study was to investigate the therapeutic effect of CD52 mAb on epithelial barrier function in animal models of IBD. Interleukin-10 knockout mice (IL-10(-/-) ) of 16 weeks with established colitis were treated with CD52 mAb once a week for 2 weeks. Severity of colitis, CD4(+) lymphocytes and cytokines in the lamina propria, epithelial expression of tight junction proteins, morphology of tight junctions, tumour necrosis factor-α (TNF-α)/TNF receptor 2 (TNFR2) mRNA expression, myosin light chain kinase (MLCK) expression and activity, as well as epithelial apoptosis in proximal colon were measured at the end of the experiment. CD52 mAb treatment effectively attenuated colitis associated with decreased lamina propria CD4(+) lymphocytes and interferon-γ/IL-17 responses in colonic mucosa in IL-10(-/-) mice. After CD52 mAb treatment, attenuation of colonic permeability, increased epithelial expression and correct localization of tight junction proteins (occludin and zona occludens protein-1), as well as ameliorated tight junction morphology were observed in IL-10(-/-) mice. CD52 mAb treatment also effectively suppressed the epithelial apoptosis, mucosa TNF-α mRNA expression, epithelial expression of long MLCK, TNFR2 and phosphorylation of MLC. Our results indicated that anti-CD52 therapy may inhibit TNF-α/TNFR2-mediated epithelial apoptosis and MLCK-dependent tight junction permeability by depleting activated T cells in the gut mucosa.

Celastrol ameliorates experimental colitis in IL-10 deficient mice via the up-regulation of autophagy

BACKGROUND

Celastrol had been proved effective in the treatment for IBD, probably with the modulation of oxidative stress, inflammatory cytokines and intestinal homeostasis. This study was aimed to investigate whether celastrol could ameliorate the inflammation of IL-10 deficient mice, a murine model of Crohn's disease (CD) with the induction of autophagy.

MATERIAL AND METHODS

The mice included were divided into four groups, ##WT group, IL-10(-/-) group, Cel group and Control group (celastrol+3-Methyladenine). Celastrol (2 mg/kg) treatment by gavage was administered to mice daily over one week. 3-Methyladenine (autophagy inhibitors) was administered at a dose of 30 mg/kg by intraperitoneal injection. The histological evaluation of the colon, tissue myeloperoxidase (MPO), and colon inflammation of mice in the four groups was evaluated and compared. Furthermore, the PI3K/Akt/mTOR pathway and the status of autophagy in intestine affected by celastrol were also assessed.

RESULTS

The one-week administration of celastrol ameliorated established colitis in IL-10 deficient mice, associated with a reduction of marked histological inflammation, a decreased colon MPO concentration and suppression of colonic proinflammatory cytokine. Furthermore, the decreased neutrophil infiltration in proximal colon and improvement of inflammation in the Cel group was much more obvious than that in the Control group. The Western blotting analysis of the PI3K/Akt/mTOR pathway and autophagy showed that celastrol treatment up-regulated the autophagy of colon tissue by suppressing the PI3K/Akt/mTOR signaling pathway.

CONCLUSIONS

Celastrol ameliorates experimental colitis in IL-10 deficient mice via the up-regulation of autophagy by suppressing the PI3K/Akt/mTOR signaling pathway.

Anemia and retinal function in a mouse model of acute colitis

Individuals with inflammatory bowel diseases (IBD) have an elevated risk of ocular inflammation. Both the anterior and posterior eye can be affected by IBD, although posterior eye dysfunction is more likely to go undetected. Little investigative attention has been directed toward the mechanisms of ocular dysfunction with IBD; however, given the prevalence of anemia in IBD and the effects of anemia on the retina, we examined the association between retinal function (electroretinography, ERG) and the anemia induced by experimental IBD, and we tested for a potential retinal benefit of acutely attenuating anemia (via red blood cell (RBC) infusion). Colitis was induced in mice in a model involving drinking water ingestion of dextran sodium sulfate (DSS), with untreated drinking water administered to controls. A subset of the DSS mice was infused with RBCs to attenuate the severity of the anemia induced by DSS. ERG signals (a-waves, b-waves, and oscillatory potential amplitudes and implicit times) were compared between the three groups of mice to evaluate retinal function. ERG amplitudes were significantly decreased in DSS mice compared to controls, with the amplitudes demonstrating a positive correlation with hematocrit, that is, the lowest ERG amplitudes were found with the most severe cases of anemia. An acute infusion of RBCs into DSS mice provided an improvement in the oscillatory potential implicit times, but no significant improvements in other ERG parameters. Despite the association between anemia and ERG signals in DSS-induced colitis, acute RBC infusion may only partially attenuate the associated retinal dysfunction.

Anti-mouse CD52 monoclonal antibody ameliorates iron-deficient anaemia in IL-10 knockout mice

Approximately 50 % of patients with inflammatory bowel disease (IBD) suffer from anaemia, with Fe deficiency being the most common cause. CD52 monoclonal antibody (mAb) targets the cell surface CD52 and is effective in depleting lymphocytes through cytolytic effects in vivo. The aim of the present study was to investigate the therapeutic effect of anti-mouse CD52 mAb on Fe-deficient anaemia in IBD. IL-10 knockout mice (IL-10− / −) of 12 weeks with established colitis were treated with anti-mouse CD52 mAb once per week for 2 weeks. Severity of colitis, blood T lymphocytes, blood Hb, haematocrit, plasma erythropoietin (EPO), serum Fe concentration, transferrin saturation, splenic Fe stores, expression of liver hepcidin mRNA, Western blotting of the phosphorylated form of Smad1/5/8 and total Smad1 were measured at the end of the experiment. IL-10− / − mice treated with CD52 mAb showed a reduction in the percentage of CD4+ and CD4+CD45+ T cells in blood and weight loss typically associated with colonic inflammation, serum levels of EPO, the expression of liver hepcidin mRNA and total Smad1 protein, while they showed an increase in Hb concentrations, haematocrit, levels of serum Fe, transferrin saturation and splenic Fe stores. The present results indicated that anti-CD52 therapy may ameliorate Fe-deficient anaemia by reducing colonic inflammation. These findings may open novel horizons in the treatment of patients with IBD by resetting of immunological homeostasis in the gut by depleting the activated T cells in the gut mucosa.

Ocular dysfunction in a mouse model of chronic gut inflammation

BACKGROUND

Ocular disease is known widely to occur in a subset of patients experiencing inflammatory bowel diseases. Although this extraintestinal manifestation has been recognized for a number of years, the pathogenetic mechanisms responsible for this distant organ inflammatory response are unknown.

METHODS

In the current study, we used a T-cell transfer model of chronic colitis in mice in which we quantified colonic inflammation, ocular function (electroretinography), ocular blood flow (intravital microscopy of the retina), intraocular pressure, and retinal hypoxia.

RESULTS

Ocular function in colitic mice was significantly impaired, with decreases in retinal b-wave amplitudes and oscillatory potentials. Moreover, retinal a waves and oscillatory potentials were delayed. Retinal blood flow was significantly reduced in the colitic mice, and this decrease in perfusion coupled with significant decreases in hematocrit would decrease oxygen delivery to the eye. Accordingly, mice with severe colitis showed increased levels of immunostaining for the hypoxia-dependent probe pimonidazole. Finally, intraocular pressures were found to be reduced in the colitic mice.

CONCLUSIONS

Ocular disease occurs in a mouse model of chronic colitis, with retinal dysfunction seeming to be related to insufficient perfusion and oxygen delivery.

Decreased retinal blood flow in experimental colitis; improvement by eye drop administration of losartan

Patients with inflammatory bowel disease suffer not only from gut inflammation, but also from extraintestinal manifestations of the disease, including ocular pathology. The mechanisms causing ocular inflammation in these patients are unknown. The purpose of the current study was to investigate the possible vascular changes occurring in the retina using a mouse model of acute colitis, that is, ingestion of dextran sodium sulfate (DSS). Intravital microscopy of anesthetized mice revealed that DSS caused a significant 30-40% decrease in retinal red blood cell velocities, and a 45% decrease in total retinal blood flow, but no changes in intraocular pressure. To determine whether the decreases in retinal perfusion could be inhibited by an angiotensin II receptor antagonist, losartan was administered by eye drops in a subset of the mice prior to the intravital microscopy measurements. Topical losartan was able to largely attenuate the altered hemodynamics induced by DSS. We conclude that angiotensin II might be a possible target for reducing the vascular changes occurring distantly in the eye during colitis.

Platelet abnormalities during colonic inflammation

Patients with inflammatory bowel disease are susceptible to microvascular thrombosis and thromboembolism. The increased incidence of thrombosis is accompanied by enhanced coagulation and abnormalities in platelet function. Clinical studies have revealed thrombocytosis, alterations in platelet activation, enhanced platelet-leukocyte interactions, and elevated plasma levels of prothrombotic cytokines. This study was directed toward determining whether the thrombocytosis, altered platelet functions, and enhanced platelet-leukocyte interactions observed in patients with inflammatory bowel disease can be recapitulated in the dextran sodium sulfate and T-cell transfer models of murine colonic inflammation. Flow cytometry was used to characterize platelet function in heparin-anticoagulated whole blood of control mice and in mice with colonic inflammation. Platelets were identified by characteristic light scattering and membrane expression of CD41. Thiazole orange labeling was used to differentiate between immature and mature platelets. Platelet activation was monitored using the expression of an activation epitope of GPIIb/IIIa integrin. The combination of CD41, CD45.2, Gr-1, F4/80, and isotype control antibodies was used to detect and quantify aggregates of leukocytes, neutrophils, and monocytes with platelets. Our results indicated that colonic inflammation is associated with thrombocytosis, leukocytosis, and the appearance of immature platelets. An increased number of circulating activated platelets was detected in colitic mice, along with the formation of aggregates of leukocytes (PLA), neutrophils (PNA), and monocytes (PMA) with platelets. Selectin blockade with fucoidin inhibited dextran sodium sulfate-induced PLA formation. The findings of this study indicate that many features of the altered platelet function detected in human inflammatory bowel disease can be reproduced in animal models of colonic inflammation.