The immune checkpoint blockade (ICB) immunotherapy has prolonged overall survival for cancer patients but the response rates are low. The resistance to ICB is likely due to compensatory upregulation of additional immune inhibitory molecules. In this study, we first systematically examined Tim-3 expression in immune cells in mouse tumors and found that Tim-3 was specifically up-regulated in a large number of Treg, conventional CD4 + , CD8 + T cells, dendritic cell 1 (DC1), and macrophage 1 (M1) in the tumor microenvironment (TME). Interestingly, Tim-3 + T cells in the TME were phenotypically effector but not "exhausted" T cells because Tim-3 + PD-1 + CD8 + T cells had a higher number of mitochondria, greater levels of glycolysis, and higher tumorspecific cytolytic activities compared to Tim-3 − PD-1 − CD8 + T cells. The combination treatment with Tim-3 and PD-1 mAbs resulted in a synergistic antitumor activity but also increased the expression of Lag-3 and GITR in TIL, demonstrating cross-regulation between multiple checkpoint molecules. Furthermore, we found that the antitumor efficacy with triple combination of Tim-3, PD-1, and Lag3 mAbs was much greater than any two antibodies. Mechanistically, we demonstrated that simultaneous targeting of Tim-3, PD-1, and Lag-3 cooperatively increased the levels of granzyme B and tumor-specific cytolytic activities of CD8 + TIL. Our data indicate that multiple checkpoint molecules are coordinately upregulated to inhibit the function of hyperactivated T cells in the TME and requirement for the simultaneous blockade of PD-1, Tim-3 and Lag3 for cancer treatment.

Rheumatoid arthritis (RA) is characterized by chronic synovial inflammation and subsequent joint destruction. Previous studies have confirmed that Th17 cells play a critical role in the pathogenesis of RA. MicroRNA (miR)-301a-3p is a regulatory factor for Th17 cells differentiation that contributes to the pathogenesis of autoimmune diseases. The purposes of this study were to identify the alteration of Th17 cells and analyze the correlation between the expression of the miR-301a-3p and the proportion of Th17 cells in RA patients. The results showed that the frequency of Th17 cells and the expression of transcription factors (RORγt and STAT3) significantly increased in the peripheral blood mononuclear cells (PBMCs) from RA patients, and the associated proinflammatory cytokines were also upregulated. We also observed that the expression of protein inhibitor of activated STAT3 (PIAS3), the main cellular inhibitor of STAT3, was attenuated in RA patients and negatively correlated with the percentage of Th17 cells in RA. Interestingly, miR-301a-3p, an inhibitor of PIAS3 expression, was overexpressed in the PBMCs from RA patients and positively correlated with the frequency of Th17 cells in patients with RA. Taken together, these data indicated that miR-301a-3p and Th17 cells were augmented in peripheral blood, which may play an important role in the process of RA.

Graves’ disease is an autoimmune disease of the thyroid gland mediated by T cells. CD28, a member of costimulatory molecules, plays a pivotal role in regulating T-cell responses. Plasma-soluble CD28 is one form of CD28 in peripheral blood. To investigate the concentrations of soluble CD28 in patients with Graves’ disease, we used a sensitive dual monoclonal antibody sandwich enzyme-linked immunosorbent assay (ELISA) to detect the soluble form of CD28. Our results suggested that mean concentrations of soluble CD28 in plasma of patients with Graves’ disease were 1.79 ±1.52 ng/ml, and levels of soluble CD28 in healthy subjects were only 0.83 ±1.35 ng/ml. Concentrations of soluble CD28 detected in patients with Graves’ disease were significantly higher than those of healthy subjects (p < 0.01). Moreover, there was a significant positive correlation between the concentrations of soluble CD28 in plasma and levels of FT3 (r = 0.663), FT4 (r = 0.624) and TRAb (r = 0.728) in serum, but a negative correlation was found between sCD28 levels and TSH (r = –0.726). Through in vitro experiments we observed that engagement of soluble CD28 protein and B7-1/B7-2 molecules expressed on dendritic cells could exert the secretion of cytokine IL-6, which may promote the production of autoantibody and aggravate Graves’ disease. Therefore, aberrant elevation of plasma-soluble CD28 in patients with Graves’ disease may reflect the dysregulation of immune system, and may serve as a useful biomarker in Graves’ disease diagnosis.