A JAK1 Selective Kinase Inhibitor and Tofacitinib Affect Macrophage Activation and Function.

BACKGROUND: Janus kinases (JAKs) mediate cytokine signaling involved in inflammatory bowel disease. The pan-JAK inhibitor tofacitinib has shown efficacy in the treatment of ulcerative colitis. However, concerns regarding adverse events due to their wide spectrum inhibition fueled efforts to develop selective JAK inhibitors. Given the crucial role of myeloid cells in intestinal immune homeostasis, we evaluated the effect of pan-JAK and selective JAK inhibitors on pro- and anti-inflammatory macrophage polarization and function (M1/M2) and in experimental colitis. METHODS: Murine bone marrow-derived macrophages or human monocytes were treated using JAK1 and JAK3 selective inhibitors (JAK1i;JAK3i) and tofacitinib and were evaluated by transcriptional, functional, and metabolic analyses. In vivo, oral administration of JAK1i and tofacitinib (10 or 30 mg/kg) was tested in both acute and acute rescue dextran sodium sulfate (DSS) colitis. RESULTS: Both tofacitinib and JAK1i but not JAK3i effectively inhibited STAT1 phosphorylation and interferon gamma-induced transcripts in M1 polarized macrophages. Strikingly, transcriptional profiling suggested a switch from M1 to M2 type macrophages, which was supported by increased protein expression of M2-associated markers. In addition, both inhibitors enhanced oxidative phosphorylation rates. In vivo, JAK1i and tofacitinib did not protect mice from acute DSS-induced colitis but ameliorated recovery from weight loss and disease activity during acute rescue DSS-induced colitis at the highest dose. CONCLUSION: JAK1i and tofacitinib but not JAK3i induce phenotypical and functional characteristics of anti-inflammatory macrophages, suggesting JAK1 as the main effector pathway for tofacitinib in these cells. In vivo, JAK1i and tofacitinib modestly affect acute rescue DSS-induced colitis.

The Future of Janus Kinase Inhibitors in Inflammatory Bowel Disease.

Inflammatory bowel diseases, such as ulcerative colitis and Crohn's disease, are disabling conditions characterised by chronic, relapsing inflammation of the gastrointestinal tract. Current treatments are not universally effective or, in the case of therapeutic antibodies, are hampered by immune responses. Janus kinase inhibitors are orally delivered small molecules that target cytokine signalling by preventing phosphorylation of Janus kinases associated with the cytokine receptor. Subsequently, phosphorylation of signal transducers and activators of transcription that relay Janus kinase signalling and transcription of cytokines in the nucleus will be diminished. Key cytokines in the pathogenesis of inflammatory bowel diseases are targeted by Janus kinase inhibitors. Several Janus kinase inhibitors are in development for the treatment of inflammatory bowel diseases. Tofacitinib, inhibiting signalling via all Janus kinase family members, was effective in phase 2 and 3 trials in moderate-severe ulcerative colitis. GSK2586184, a Janus kinase 1 selective inhibitor, induced clinical and endoscopic response in ulcerative colitis; however, the study was discontinued at an early stage due to liver toxicity observed in systemic lupus patients receiving the drug. Filgotinib, a Janus kinase 1 selective inhibitor investigated in treatment of Crohn's disease, was superior to placebo. As adverse events associated with the broad immunological effect of these agents have been reported, the future application of these drugs is potentially limited. We will discuss the treatment efficacy of Janus kinase inhibition in inflammatory bowel diseases, how current Janus kinase inhibitors available target immune responses relevant in inflammatory bowel disease, and whether more specific kinase inhibition could be effective.

Delivery of healthy babies after natalizumab use for multiple sclerosis: a report of two cases.

BACKGROUND: In current literature, no data on safety in pregnancy for new drugs in the treatment of multiple sclerosis (MS) like natalizumab (Tysabri®), a humanized monoclonal antibody against α4 integrins, are yet available. In the management of MS, natalizumab is the first monoclonal antibody approved to the market. METHODS: We describe the pregnancy and outcome in two women with MS using natalizumab. The first patient used it in the periconceptional period, and the second patient used it in both the periconceptional period and throughout gestation. RESULTS: The antenatal course of the first patient was complicated by an exacerbation of MS. The second patient did not experience MS relapses during pregnancy, while still using natalizumab. The newborns did not show any abnormalities postnatal and at 6 weeks' follow-up. CONCLUSIONS: This is the first detailed report on pregnancy and delivery of two babies after maternal treatment of MS with natalizumab. From the small number of cases on the usage of natalizumab during pregnancy in literature, we cannot conclude whether the use of natalizumab is safe, and long-term effects are not known. Further research is needed to establish the exact effects on pregnancy and intrauterine development as well as the long-term effects. Prenatal counseling with thorough explanation of the risks and careful decision making is advisable.