"Small" Intestinal Immunopathology Plays a "Big" Role in Lethal Cytokine Release Syndrome, and Its Modulation by Interferon-γ, IL-17A, and a Janus Kinase Inhibitor

Chimeric antigen receptor T cell (CART) therapy, administration of certain T cell-agonistic antibodies, immune check point inhibitors, coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome–coronavirus 2 (SARS-CoV-2) and Toxic shock syndrome (TSS) caused by streptococcal as well as staphylococcal superantigens share one common complication, that is T cell-driven cytokine release syndrome (CRS) accompanied by multiple organ dysfunction (MOD). It is not understood whether the failure of a particular organ contributes more significantly to the severity of CRS. Also not known is whether a specific cytokine or signaling pathway plays a more pathogenic role in precipitating MOD compared to others. As a result, there is no specific treatment available to date for CRS, and it is managed only symptomatically to support the deteriorating organ functions and maintain the blood pressure. Therefore, we used the superantigen-induced CRS model in HLA-DR3 transgenic mice, that closely mimics human CRS, to delineate the immunopathogenesis of CRS as well as to validate a novel treatment for CRS. Using this model, we demonstrate that (i) CRS is characterized by a rapid rise in systemic levels of several Th1/Th2/Th17/Th22 type cytokines within a few hours, followed by a quick decline. (ii) Even though multiple organs are affected, small intestinal immunopathology is the major contributor to mortality in CRS. (iii) IFN-γ deficiency significantly protected from lethal CRS by attenuating small bowel pathology, whereas IL-17A deficiency significantly increased mortality by augmenting small bowel pathology. (iv) RNA sequencing of small intestinal tissues indicated that IFN-γ-STAT1-driven inflammatory pathways combined with enhanced expression of pro-apoptotic molecules as well as extracellular matrix degradation contributed to small bowel pathology in CRS. These pathways were further enhanced by IL-17A deficiency and significantly down-regulated in mice lacking IFN-γ. (v) Ruxolitinib, a selective JAK-1/2 inhibitor, attenuated SAg-induced T cell activation, cytokine production, and small bowel pathology, thereby completely protecting from lethal CRS in both WT and IL-17A deficient HLA-DR3 mice. Overall, IFN-γ-JAK-STAT-driven pathways contribute to lethal small intestinal immunopathology in T cell-driven CRS.

Ruxolitinib, a selective JAK1/2 inhibitor, for the treatment of serious diseases caused by Staphylococcus aureus superantigens

Staphylococcal superantigens (SSAgs), produced by Staphylococcus aureus, non-specifically activate 30–50% of all CD4+ and CD8+ T cells expressing certain T cell receptor (TCR) Vb gene families. SSAg-activated T cells rapidly produce large quantities of cytokines and chemokines resulting in a systemic inflammatory response syndrome (SIRS), which culminates in multi organ failure (MOF) and ultimately death. Through this process, SSAgs play a significant role in the immunopathogenesis of pneumonia, sepsis, and toxic shock syndrome. Because most cytokines produced during SIRS act through the Janus Kinase (JAK) signaling pathway, we hypothesized that therapeutics inhibiting JAK functions would attenuate SIRS, MOF, and lower mortality caused by SSAgs. We tested ruxolitinib (RUXO), an FDA-approved selective JAK 1/2 inhibitor. Several in vitro and in vivo studies were performed using HLA-DR3 transgenic mice because SSAgs bind to HLA class II molecules with higher affinity. In vitro, at 100, 10, and 1 mm concentrations, RUXO significantly inhibited SSAg-induced upregulation of CD25 and CD69 on both CD4+ and CD8+ T cell subsets as well as SSAg-induced production of IL-2, IL-17, and IFN-g in a dose-dependent manner at 24 and 48 hours. For in vivo studies, mice (5–6 per group) were gavaged with RUXO (100 mg/kg) or vehicle, twice daily on days −1, 0 and 1, challenged with SSAg (20 mg/mouse, i.p) on day 0 and euthanized on day 2. SSAg-induced SIRS, thymocyte deletion, upregulation of activation markers (CD69 and CD25), and immunopathology were significantly attenuated in RUXO-treated mice compared to vehicle-treated mice. Overall, JAK inhibitors such as ruxolitinib can be used as an adjunct to treat serious diseases caused by SSAg.

[Synoviorthesis of the knee joint with 32P-chromic phosphate (author's transl)]

32P-CrPO4 in colloid form has been used for radiosynoviorthesis. There were no acute or subacute side reactions observed. The therapy results were equal to those following 90Y colloid application: 60% very good to good results after 6 months. The substance can be kept on stock since it has a relatively long shelf-life. The cost reduction and the simplification of treatment planning have proved to be the most important advantages of 32P-CrPO4.

Die Synoviorthese des Kniegelenkes mit 32P-Chromphosphat

32P-CrPO4 in kolloidaler Form wurde für die Radiosynoviorthese des Kniegelenks verwendet. Akute bis subakute Nebenwirkungen wurden nicht beobachtet. Die Behandlungsergebnisse waren denen nach 90Y-Kolloid-Gabe gleichwertig: 60 % sehr gute bis gute Erfolge nach 6 Monaten. Die Substanz kann auf Vorrat gehalten werden. Die Kosten-sparenden Effekte und die Vereinfachung in der Therapieplanung werden als die wichtigsten Vorzüge des 32P-CrPO4 herausgestellt.