Tolerogenic dendritic cells induced the enrichment of CD4+Foxp3+ regulatory T cells via TGF-ß in mesenteric lymph nodes of murine LPS-induced tolerance model.

Endotoxin tolerance is an important state for the prevention of lethal infection and inflammatory response, which is closely associated with the participation of innate immune cells. Moreover, mesenteric lymph nodes (MLNs)-resident immune cells, such as CD4+Foxp3+ regulatory T (Treg) cells and dendritic cells, play important roles in the maintenance of peripheral immune tolerance. However, the potential roles of these cells in MLNs in the development of endotoxin tolerance remain largely unknown. Recent research work showed that CD4+Foxp3+ Treg cells contributed to the development of endotoxin tolerance. Here, we further analyzed the possible change on CD4+Foxp3+Tregs population in MLNs in murine LPS-induced endotoxin tolerance model. Our data showed that the proportion and absolute number of CD4+Foxp3+Tregs, expressing altered levels of CTLA4 and GITR, significantly increased in MLNs of murine LPS-induced tolerance model. Moreover, the expression level of TGF-ß in MLNs also increased obviously. Furthermore, TGF-ß blockade could obviously reduce the proportion and absolute number of CD4+Foxp3+Tregs in MLNs and subsequently impair the protection effect against LPS rechallenge. Of note, we found that tolerogenic dendritic cell (Tol-DC), expressing lower levels of MHC-II and CD86 molecules, dominantly secreted TGF-ß in MLNs in murine LPS-induced tolerance model. In all, our data provided an unknown phenomenon that the total cell number of CD4+Foxp3+Tregs significantly increased in MLNs in endotoxin tolerance, which was related to MLN-resident TGF-ß secreting CD11c+DCs, providing a new fundamental basis for the understanding on the potential roles of MLN-resident immune cells in the development of endotoxin tolerance.

[Effects of glucocorticoids on the expression of GTIR and apoptosis of the CD4(+)CD25(+)CD127(dim/-) T cells in patients with systemic lupus erythematosus].

OBJECTIVE: To investigate the expression of glucocorticoid-induced tumor necrosis factor receptor (GITR) and apoptosis of CD4(+)CD25(+)CD127(dim/-) T cells of the patients with systemic lupus erythematosus (SLE),and to analyze its clinical value. METHODS: A total of 28 patients with a diagnosis of SLE according to the American College of Rheumatology (ACR) 1997 criteria were included in the study. The SLE patients were divided into active group (SLEDAI≥10) and inactive group (SLEDAI<10) according to the SLE disease activity index (SLEDAI). Active group included 15 patients and inactive group 13 patients. Clinical and laboratory data of the patients with SLE were recorded. In this study 12 normal volunteers without history of autoimmune diseases were also included. Peripheral blood CD4(+)CD25(+)CD127(dim/-) T cells were isolated by magnetic beads sorting. We classified them into two subgroups: the blank group and the therapeutic dose group (dexamethasone dose was 5×10(-2) mg/L and the peripheral blood CD4(+)CD25(+)CD127(dim/-) T cells with dexamethasone were cultured for 48 hours). The expressions of GITR and Annexin V were analyzed by flow cytometry before and after the culture. The correlations between GITR levels, apoptosis rates of these subsets and the clinic, laboratory parameters of SLE were analyzed. RESULTS: GITR levels and apoptosis rates in the patients with SLE were significantly higher than those in the normal control group (P=0.016; P=0.049). The expression levels of GITR on Treg cells between the blank group and the therapeutic dose group were found be of no significant difference in the patients with SLE (P>0.05), but in the normal group, the expression levels of GITR in the therapeutic dose group were higher than those in the blank group (P=0.034). After adding dexamethasone, the apoptosis rates of Treg cells were decreased in the patients with SLE, the difference was statistically significant (P=0.033); But in the normal control group, the apoptosis rate of Treg cells was higher in the therapeutic dose group than in the blank group (P=0.012). The expression levels of GITR on Treg cells were significantly positively correlated with SLEDAI, but were correlated negatively with the C3. CONCLUSION: The GITR is pathologically expressed on Treg cells in SLE, which may be used as an immunological index of SLE disease activity; Glucocorticoids may regulate immune abnormalities in patients with SLE by inhibiting the apoptosis of Treg cells.

Second- and third-generation drugs for immuno-oncology treatment-The more the better?

Recent success in cancer immunotherapy (anti-CTLA-4, anti-PD1/PD-L1) has confirmed the hypothesis that the immune system can control many cancers across various histologies, in some cases producing durable responses in a way not seen with many small-molecule drugs. However, only less than 25% of all patients do respond to immuno-oncology drugs and several resistance mechanisms have been identified (e.g. T-cell exhaustion, overexpression of caspase-8 and ß-catenin, PD-1/PD-L1 gene amplification, MHC-I/II mutations). To improve response rates and to overcome resistance, novel second- and third-generation immuno-oncology drugs are currently evaluated in ongoing phase I/II trials (either alone or in combination) including novel inhibitory compounds (e.g. TIM-3, VISTA, LAG-3, IDO, KIR) and newly developed co-stimulatory antibodies (e.g. CD40, GITR, OX40, CD137, ICOS). It is important to note that co-stimulatory agents strikingly differ in their proposed mechanism of action compared with monoclonal antibodies that accomplish immune activation by blocking negative checkpoint molecules such as CTLA-4 or PD-1/PD-1 or others. Indeed, the prospect of combining agonistic with antagonistic agents is enticing and represents a real immunologic opportunity to 'step on the gas' while 'cutting the brakes', although this strategy as a novel cancer therapy has not been universally endorsed so far. Concerns include the prospect of triggering cytokine-release syndromes, autoimmune reactions and hyper immune stimulation leading to activation-induced cell death or tolerance, however, toxicity has not been a major issue in the clinical trials reported so far. Although initial phase I/II clinical trials of agonistic and novel antagonistic drugs have shown highly promising results in the absence of disabling toxicity, both in single-agent studies and in combination with chemotherapy or other immune system targeting drugs; however, numerous questions remain about dose, schedule, route of administration and formulation as well as identifying the appropriate patient populations. In our view, with such a wealth of potential mechanisms of action and with the ability to fine-tune monoclonal antibody structure and function to suit particular requirements, the second and third wave of immuno-oncology drugs are likely to provide rapid advances with new combinations of novel immunotherapy (especially co-stimulatory antibodies). Here, we will review the mechanisms of action and the clinical data of these new antibodies and discuss the major issues facing this rapidly evolving field.