Background: IL10 is an immune-regulatory cytokine that plays an important role in the maintenance of intestinal homeostasis. Loss-of-function mutations in IL10, IL10RA or IL10RB cause severe intestinal inflammation and is refractory to conventional immunosuppressive medications. We have recently shown that IL1β is highly upregulated in IL10R deficiency and blocking IL1 attenuated colitis in an IL10R-deficient mouse model. Thus, we elected to treat one patient with medical-refractory severe inflammatory bowel disease secondary to IL10RA mutation with anakinra, an IL1 receptor antagonist to evaluate its potential as the bridge to the allogeneic hematopoietic stem cell transplantation.
Methods: The intestinal inflammation was evaluated by endoscopy and histology. Lamina propria mononuclear cells (LPMC) were isolated from both biopsy terminal ileum samples pre-and post-anakinra treatment of the IL10R-deficient patient and surgical terminal ileum samples of Crohn's disease (CD) patients by mechanically disassociation and enzyme digestion. Peripheral blood mononuclear cells were isolated by Ficoll-Pague density gradient centrifugation. For flow cytometry analysis, lymphocytes were stimulated with 200ng/ml PMA, 1μg/ml Ionomycin and 1×Monensin for 4.5 hours, stained with antibodies (anti-Human Lineage Cocktail 3 or anti-CD3, anti-CD45/CD56/CD117/CD127/NKp44/IL22/IL17A and IFNγ).
Results: Anakinra therapy led to marked clinical, endoscopic, and histological improvement within a few weeks for the IL10R deficient patient. The frequency of IL22-producing lymphocytes among Lineage (+) CD45 (+) LPMC greatly increased from 2.17% pre-anakinra to 50.9% post-anakinra. Analysis of an additional ileal biopsy 3 months later demonstrated that the number further increased to 53.9%. Additionally, we detected a trend towards reduction of the IL22-producing lymphocytes (p=0.07) among Lineage (+) CD45 (+) LPMC in the inflamed tissue (2.89%, n=9) compared to unaffected tissue (5.75%, n=3) of those CD patients. Furthermore, we observed a significant increase in blood-borne TH22 and TH17 cells, both single producers and IL22/IFNγ, IL17A/IFNγ double producers, in the patient, as well as in CD subjects.
Conclusions: Herein, we present a case of a patient with severe IBD due to an IL10RA mutation whose intestine showed signs of mucosal healing accompanied by increased frequency of IL22-producing lymphocytes in the lamina propria of the terminal ileum after anakinra treatment. The increase in IL22, which promoted tissue repair, might have had an important role in the recovery of this patient and suggests an additional important mechanistic mode of action of anakinra in the gut.