Leukocyte - Cerebral Endothelial Cell Interactions in the Brain Lead to Anxiety-like Behaviour in Experimental Colitis

BACKGROUNDBehavioral comorbidities, such as anxiety and depression, are a prominent feature of IBD. The signals from the inflamed gut that cause changes in the brain leading to these behavioral comorbidities remain to be fully elucidated. We tested the hypothesis that enhanced leukocyte - cerebral endothelial cell interactions in experimental colitis initiate neuroimmune activation leading to anxiety-like behaviour.METHODSMale and female mice treated with dextran sodium sulfate were studied at the peak of acute colitis. Circulating leukocyte populations were determined using flow cytometry. Leukocyte - cerebral endothelial cell interactions were examined using intravital microscopy in mice treated with anti-integrin antibodies. Brain cytokine and chemokines were assessed using a multiplex assay in animals treated with anti-α4β7 integrin. Anxiety-like behavior was assessed using an elevated plus maze in animals after treatment with an intracerebroventricular injection of interleukin 1 receptor antagonist. RESULTSThe proportion of classical monocytes expressing α4β7 integrin was increased in peripheral blood of mice with colitis. An increase in the number of rolling and adherent leukocytes on cerebral endothelial cells was observed, the majority of which were neutrophils. Treatment with anti-α4β7 integrin significantly reduced the number of rolling leukocytes. After anti-Ly6C treatment to deplete monocytes, the number of rolling and adhering neutrophils were significantly reduced in mice with colitis. Interleukin-1β levels were elevated in the brain and treatment with anti-α4β7 significantly reduced them. Enhanced anxiety-like behaviour in mice with colitis was reversed by treatment with interleukin 1 receptor antagonist. CONCLUSIONSα4β7 integrin expressing monocytes direct the recruitment of neutrophils to the brain vasculature, leading to elevated cytokine levels that mediate anxiety-like behaviour in experimental colitis.

Towards a Treatment for Neuroinflammation in Epilepsy: Interleukin-1 Receptor Antagonist, Anakinra, as a Potential Treatment in Intractable Epilepsy

Febrile Infection-Related Epilepsy Syndrome (FIRES) is a unique catastrophic epilepsy syndrome, and the development of drug-resistant epilepsy (DRE) is inevitable. Recently, anakinra, an interleukin-1 receptor antagonist (IL-1RA), has been increasingly used to treat DRE due to its potent anticonvulsant activity. We here summarized its effects in 38 patients (32 patients with FIRES and six with DRE). Of the 22 patients with FIRES, 16 (73%) had at least short-term seizure control 1 week after starting anakinra, while the remaining six suspected anakinra-refractory cases were male and had poor prognoses. Due to the small sample size, an explanation for anakinra refractoriness was not evident. In all DRE patients, seizures disappeared or improved, and cognitive function improved in five of the six patients following treatment. Patients showed no serious side effects, although drug reactions with eosinophilia and systemic symptoms, cytopenia, and infections were observed. Thus, anakinra has led to a marked improvement in some cases, and functional deficiency of IL-1RA was indicated, supporting a direct mechanism for its therapeutic effect. This review first discusses the effectiveness of anakinra for intractable epileptic syndromes. Anakinra could become a new tool for intractable epilepsy treatment. However, it does not currently have a solid evidence base.

Changes in expression of NLRP3 inflamasome and IL-1β in the development of oxazolone-induced colitis in rats and on the background of administration of simvastatin and interleukin-1β receptor antagonist

The aim. To study the expression of mRNA of the NLRP3 inflammasome and proinflammatory cytokine IL-1β in the inflamed colon of rats with experimental oxazolone-induced colitis and against the background of the introduction of simvastatin and antagonist of interleukin-1 receptors. Materials and methods. Experiments were carried out on male Wistar rats aged 8 months (body mass 120–150 g). Tissue samples were obtained from rats with experimental oxazolone-induced colitis (n = 20), rats with oxazolone-induced colitis treated with simvastatin (n = 20); rats with oxazolone-induced colitis treated with interleukin-1 receptor antagonist (n = 20) and control animals (n = 10). Clinical signs of colitis were evaluated by the clinical index of disease activity on the following parameters: weight loss, stool consistency and animal behavior. For macroscopic assessment of the development of colitis areas of inflammation and ulceration were investigated. For histological evaluation of lesions, sections of the intestine were stained with hematoxylin and eosin and cellular inflammatory infiltrates, epithelial hyperplasia, ulceration and loss of intestinal glands were studied. IL-1β and NLRP3 inflammasome mRNA expression was analyzed by real-time reverse transcriptase-polymerase chain reaction. Results. Animals treated with oxazolone rapidly developed colitis marked by weight loss and diarrhea peaking by day 2 after oxazolone administration and leading to death of 40 % of the rats by day 4. The histological observation showed inflammatory cell infiltration, including polymorphonuclear leukocytes and multiple erosive lesions in the large intestine. We determined that the expression level of the proinflammatory cytokine IL-1β is increased in colon samples of rats with oxazolone-induced colitis. IL-1β expression is increased 3.5‐fold in inflamed colon compared to uninflamed tissue. Administration of simvastatin and an interleukin-1 receptor antagonist to rats with oxazolone-induced colitis resulted in a 30 % and 2-fold decrease expression of IL-1β in colon samples. In addition, we examined NLRP3 expression in these tissues. RT‐PCR analysis demonstrates a 71‐fold increased expression of NLRP3 mRNA expression in colon samples tested. Administration of simvastatin and an interleukin-1 receptor antagonist to rats with oxazolone-induced colitis resulted in a 2.5- to 3.0-fold decrease expression of NLRP3 mRNA in colon samples. Conclusions. IL-1β and NLRP3 mRNA expression levels were elevated in the inflamed colon of rats with experimental oxazolone-induced colitis. Administration of simvastatin and an interleukin-1 receptor antagonist against the background of colitis caused a decrease in the expression levels of IL-1β and NLRP3 mRNA in the tissues of the intestine. Detection of abnormal expression of IL-1β and NLRP3 mRNA could provide insights into pathogenesis of Crohn's disease, and may help to identify future potential targets for therapeutic strategies in people with inflammatory bowel disease.