Plasma CXCL9 elevations correlate with chronic GVHD diagnosis.

There are no validated biomarkers for chronic GVHD (cGVHD). We used a protein microarray and subsequent sequential enzyme-linked immunosorbent assay to compare 17 patients with treatment-refractory de novo-onset cGVHD and 18 time-matched control patients without acute or chronic GVHD to identify 5 candidate proteins that distinguished cGVHD from no cGVHD: CXCL9, IL2Rα, elafin, CD13, and BAFF. We then assessed the discriminatory value of each protein individually and in composite panels in a validation cohort (n = 109). CXCL9 was found to have the highest discriminatory value with an area under the receiver operating characteristic curve of 0.83 (95% confidence interval, 0.74-0.91). CXCL9 plasma concentrations above the median were associated with a higher frequency of cGVHD even after adjustment for other factors related to developing cGVHD including age, diagnosis, donor source, and degree of HLA matching (71% vs 20%; P < .001). A separate validation cohort from a different transplant center (n = 211) confirmed that CXCL9 plasma concentrations above the median were associated with more frequent newly diagnosed cGVHD after adjusting for the aforementioned factors (84% vs 60%; P = .001). Our results confirm that CXCL9 is elevated in patients with newly diagnosed cGVHD.

Notch signaling regulates T cell accumulation and function in the central nervous system during experimental autoimmune encephalomyelitis.

Systemic inhibition of Notch signaling was previously shown to attenuate experimental autoimmune encephalomyelitis (EAE), a disease model of multiple sclerosis in mice. Different studies attributed these effects to decreased T-bet and IFN-γ expression, enhanced regulatory T cell function, reduced T cell chemotaxis to the CNS, or impaired Th9 cell differentiation. Interpretation of these heterogeneous findings is difficult because past experimental strategies did not ensure complete Notch inhibition in T cells and because many cell populations could be affected by systemic Notch blockade. To resolve the role of Notch in T cells during EAE, we used the pan-Notch inhibitor dominant-negative form of Mastermind-like 1 (DNMAML), as well as several complementary loss-of-function approaches specifically in myelin-reactive T cells. Notch inhibition in T cells profoundly decreased EAE incidence and severity. Notch-deprived myelin-reactive T cells had preserved activation and effector differentiation in secondary lymphoid tissues. However, Notch-deprived T cells failed to accumulate in the CNS after immunization. Parking wild-type and DNMAML T cells together in bone marrow chimeras increased accumulation of Notch-deprived T cells in the CNS after immunization but did not prevent EAE, indicating the absence of dominant suppression by DNMAML T cells. Analysis of CNS-infiltrating DNMAML T cells revealed markedly defective IL-17A and IFN-γ production, despite preserved T-bet expression. Collectively, our findings capture the profound overall effects of Notch signaling in myelin-reactive T cells and demonstrate that Notch controls the accumulation and pathogenic functions of CD4(+) T cells within their target organ but not in lymphoid tissues during EAE.