Th17 cell differentiation and pathogenicity depend on metabolic reprogramming inducing shifts toward glycolysis. Here, we show that the pyruvate kinase M2 (PKM2), a glycolytic enzyme required for cancer cell proliferation and tumor progression, is a key factor mediating Th17 cell differentiation and autoimmune inflammation. We found that PKM2 is highly expressed throughout the differentiation of Th17 cells in vitro and during experimental autoimmune encephalomyelitis (EAE) development. Strikingly, PKM2 is not required for the metabolic reprogramming and proliferative capacity of Th17 cells. However, T cell–specific PKM2 deletion impairs Th17 cell differentiation and ameliorates symptoms of EAE by decreasing Th17 cell–mediated inflammation and demyelination. Mechanistically, PKM2 translocates into the nucleus and interacts with STAT3, enhancing its activation and thereby increasing Th17 cell differentiation. Thus, PKM2 acts as a critical nonmetabolic regulator that fine-tunes Th17 cell differentiation and function in autoimmune-mediated inflammation.

Background Few data exist on the degree of interstitial myocardial fibrosis in patients with classical low-flow, low-gradient aortic stenosis (LFLG-AS) and its association with left ventricular flow reserve (FR) on dobutamine stress echocardiography. This study sought to evaluate the diffuse interstitial fibrosis measured by T1 mapping cardiac magnetic resonance technique in LFLG-AS patients with and without FR. Methods Prospective study including 65 consecutive patients (41 LFLG-AS [mean age, 67.1±8.4 years; 83% men] and 24 high-gradient aortic stenosis used as controls) undergoing dobutamine stress echocardiography to assess FR and cardiac magnetic resonance to determine the extracellular volume (ECV) fraction of the myocardium, indexed ECV (iECV) to body surface area and late gadolinium enhancement. Results Interstitial myocardial fibrosis measured by iECV was higher in patients with LFLG-AS with and without FR as compared with high-gradient aortic stenosis (35.25±9.75 versus 32.93±11.00 versus 21.19±6.47 mL/m 2 , respectively; P <0.001). However, both ECV and iECV levels were similar between LFLG-AS patients with and without FR ( P =0.950 and P =0.701, respectively). Also, FR did not correlate significantly with ECV (r=−0.16, P =0.31) or iECV (r=0.11, P =0.51). Late gadolinium enhancement mass was also similar in patients with versus without FR but lower in high-gradient aortic stenosis (13.3±10.2 versus 10.5±7.5 versus 4.8±5.9 g, respectively; P =0.018). Conclusions Patients with LFLG-AS have higher ECV, iECV, and late gadolinium enhancement mass compared with high-gradient aortic stenosis. Moreover, among patients with LFLG-AS, the degree of myocardial fibrosis was similar in patients with versus those without FR. These findings suggest that diffuse myocardial fibrosis may not be the main factor responsible for the absence of FR in LFLG-AS patients.

Background Although literature demonstrates that an increase in both the number and suppressive function of CD4+FOXP3+T regulatory cells (Tregs) during sepsis contributes to an immunosuppressed state, little is known about the identity of these cells. Methods Using the sepsis mouse model of cecal ligation and puncture (CLP), we analysed the frequency and molecular signature of the TIGIT + and TIGIT- Tregs subsets by flow cytometry and qPCR. Additionally, ST2-/- and STAT6-/- mice were submitted to CLP or rIL-33 treatment to investigate the mechanism through which TIGIT+Tregs differentiate during sepsis. Results Sepsis was marked by the sustained expansion of the highly suppressive TIGIT +Tregs subset, which expresses Helios, Neuropilin-1, and high levels of Tnfrsf18 and Pdcd1 at 15d after CLP. The increase of the TIGIT +Tregs was accompanied by higher susceptibility to nosocomial bacteria challenge, suggesting its involvement with post-sepsis immunosuppression. Mechanistically, we found that the ST2 deletion abrogated the expansion of the TIGIT+Treg subset during sepsis. Furthermore, the treatment with rIL-33 resulted in the expansion of TIGIT+Tregs depending on the STAT6 and M2 macrophages. Conclusions These findings demonstrated that only the TIGIT+Tregs remain stably expanded at the late phase of sepsis. Moreover, the expansion of TIGIT +Tregs is dependent on the IL-33/ST2/STAT6/M2 macrophages axis.

Medulloblastoma (MB) is the most common malignant brain tumor occurring in children, and although high long-term survival rates have been reached with current therapeutic protocols, several neurological injuries are still observed among survivors. It has been shown that the development of MB is highly dependent on the microenvironment surrounding it and that the CXCL12 chemokine and its receptor, CXCR4 and the Sonic Hedgehog (SHH) pathway are crucial for cerebellar development, coordinating proliferation and migration of embryonic cells and malfunctions in these axes can lead to MB development. Indeed, the concomitant overactivation of these axes was suggested to define a new MB molecular subgroup. New molecules are being studied, aiming to inhibit either CXCR4 or the SHH pathways and have been tested in preclinical settings for the treatment of cancers. The use of these molecules could improve MB treatment and save patients from aggressive surgery, chemotherapy and radiotherapy regimens, which are responsible for severe neurological consequences. This review aims to summarize current data about the experimental inhibition of CXCR4 and SHH pathways in MB and its potential implications in treatment of this cancer.

No abstract