The combination of gene hyperamplification and PD-L1 expression as a biomarker for the clinical benefit of tislelizumab in gastric/gastroesophageal junction adenocarcinoma.

BACKGROUND: In solid tumor Phase 1/2 trials (NCT02407990; NCT04068519), tislelizumab demonstrated clinical benefit, including in advanced gastroesophageal adenocarcinoma (GEA). However, the majority of patients with GEA did not respond, highlighting the need to understand mechanisms of resistance and identify predictive biomarkers for response. METHODS: All tislelizumab-treated patients with GEA from the Phase 1/2 trials were included (N = 105). Programmed death-ligand 1 (PD-L1) expression (Tumor Area Positivity [TAP] ≥ 5%), interferon gamma (IFNγ)-related gene signature, gene expression profile, tumor mutational burden (TMB), and gene hyperamplification (HA) were analyzed for correlation with tislelizumab. RESULTS: A moderate association was observed between PD-L1 TAP ≥ 5%, IFNγ gene signature, TMB-high and efficacy. A potential correlation between hyperamplification (HA +) and worse outcomes with programmed cell death protein 1 (PD-1) inhibition was identified. Hyperamplified genes were mainly enriched in cancer progression pathways, including cell cycle and RTK-RAS-PI3K pathways. Joint PD-L1 TAP ≥ 5% and lack of hyperamplification showed the most favorable benefit with an objective response rate of 29.4%, and median progression-free survival and overall survival of 4.1 and 14.7 months, respectively. Tumors with TAP ≥ 5% and HA - had inflamed immune signatures with increased immune cell infiltration, enhanced anti-tumor cytotoxic activity and antigen presentation signatures. Findings were validated in two independent gastric and gastrointestinal cancer cohorts treated with immune checkpoint inhibitors. CONCLUSIONS: In GEA, PD-L1 positivity, IFNγ-related gene signature and TMB-high status were positively associated with tislelizumab clinical benefit, whereas HA was associated with worse clinical outcomes. Combining PD-L1 positivity and HA - may help identify patients more likely to benefit from PD-1 blockade.

Foxp1 Negatively Regulates T Follicular Helper Cell Differentiation and Germinal Center Responses by Controlling Cell Migration and CTLA-4.

T follicular helper (Tfh) cells play an essential role in the formation of germinal centers (GC) and generation of high-affinity Abs. The homing of activated CD4+ T cells into B cell follicles and the involvement of key costimulatory and coinhibitory molecules are critical in controlling both the initiation and the magnitude of GC responses. Meanwhile, studies have shown that a high number of single clone B cells leads to intraclonal competition, which inhibits the generation of high-affinity Abs. Our previous work has shown that transcription factor Foxp1 is a critical negative regulator of Tfh cell differentiation. In this study, we report that the deletion of Foxp1 leads to a high proportion of activated CD4+ T cells homing into B cell follicles with faster kinetics, resulting in earlier GC formation. In addition, we show that Foxp1-deficient Tfh cells restore the generation of high-affinity Abs when cotransferred with high numbers of single clone B cells. We find that Foxp1 regulates the expression levels of cytotoxic T lymphocyte-associated Ag-4 (CTLA-4) in activated CD4+ T cells and that Ctla4 is a direct Foxp1 target. Finally, we demonstrate that CTLA-4 expression on conventional CD4+ T cells plays a cell-intrinsic role in Tfh cell differentiation in vivo, and CTLA-4 blockade helps abolish the intraclonal competition of B cells in generating high-affinity Abs.

Regulation of Metabolism Across Different Subsets of T Cells in Cancer.

T cells play a critical role to defend against tumor and maintain immune homeostasis. The diverse functions of T cells require precise regulation of metabolic pathways. Recent studies reveal that metabolic changes are tightly linked to the activation and function of T cells. Given the importance of these cells in tumor progression, it is important to understand how the tumor microenvironment regulates metabolism of T cells and how the metabolic reprogramming of T cells affects tumor growth. Here, we review new findings and discuss how metabolic reprogramming of different types of T cells affects the immune response in tumors.

Poly(ADP-ribosyl)ation of FOXP3 Protein Mediated by PARP-1 Protein Regulates the Function of Regulatory T Cells.

Poly(ADP-ribose) polymerase 1 (PARP-1) is an ADP-ribosylating enzyme participating in diverse cellular functions. The roles of PARP-1 in the immune system, however, have not been well understood. Here we find that PARP-1 interacts with FOXP3 and induces its poly(ADP-ribosyl)ation. By using PARP-1 inhibitors, we show that reduced poly(ADP-ribosyl)ation of FOXP3 results in not only FOXP3 stabilization and increased FOXP3 downstream genes but also enhanced suppressive function of regulatory T cells. Our results suggest that PARP-1 negatively regulates the suppressive function of Treg cells at the posttranslational level via FOXP3 poly(ADP-ribosyl)ation. This finding has implications for developing PARP-1 inhibitors as potential agents for the prevention and treatment of autoimmune diseases.

DNMT1 cooperates with MBD4 to inhibit the expression of Glucocorticoid-induced TNFR-related protein in human T cells.

Glucocorticoid-induced TNFR-related protein (GITR) is constitutively expressed in T regulatory (Treg) cells and regulates their suppressive function. We identified two methylated CpG islands in the Gitr locus. Using a ChIP assay, we demonstrate that both DNMT1 and methyl-CpG-binding domain Protein 4 (MBD4) bind to the Gitr promoter. Moreover, knockdown of DNMT1 decreases the binding activity of MBD4. We observed much higher levels of both DNMT1 and MBD4 in human CD4+ CD25- conventional T (Tconv) cells. Moreover, co-overexpression of DNMT1 and MBD4 in Treg cells significantly inhibits GITR expression and impairs their suppressive activity. Our results reveal a novel molecular mechanism by which MBD4 inhibits GITR expression in a DNMT1-dependent manner.

Cimetidine down-regulates stability of Foxp3 protein via Stub1 in Treg cells.

Foxp3-expressing Treg cells have been well documented to provide immune regulation by promoting immune tolerance and suppressing immune over-reaction. Cimetidine (CIM), used to inhibit stomach acid secretion, has been reported to promote immune responses and suppress Treg cell function in several studies. However, the underlying mechanism is unknown. To investigate CIM effects on the suppressive function of Treg and Foxp3, here we used CIM to stimulate human CD4+CD25+ Treg cells and Jurkat T cells and evaluated changes of Foxp3 expression and stability. Our data showed that CIM leads to a reduction of Foxp3 via E3 ligase Stub1-mediated proteosomal degradation, which is dependent on an activated PI3K-AKT-mTOR pathway. Thus, CIM affects the suppressive function of Treg cells by destabilizing their Foxp3 expression.

IL-17A Exacerbates Fibrosis by Promoting the Proinflammatory and Profibrotic Function of Orbital Fibroblasts in TAO.

CONTEXT: The development of thyroid-associated ophthalmopathy (TAO) is associated with self-immune dysfunction. Recent findings in TAO and Graves' disease indicate that IL-17A may also be involved in the autoimmunity of TAO. OBJECTIVE: We sought to investigate the pathogenic function of IL-17A-producing T cells in TAO. DESIGN/SETTING/PARTICIPANTS: Blood samples and orbital fibroblasts (OFs) were collected from TAO patients and healthy subjects. MAIN OUTCOME MEASURES: Flow cytometry, real-time PCR, cytokine-specific ELISA, and Western blotting were performed. RESULTS: Here, we showed a significantly higher proportion of IL-17A-producing T cells in TAO patients and the recruitment of both CD4(+) and CD8(+) T cells in TAO orbits. TAO orbital tissues expressed more IL-17A receptor, IL-17A, and its related cytokines, with severe fibrotic change compared with normal controls. Furthermore, we validated that IL-17A could enhance the proinflammatory function of OFs and stimulate the production of extracellular matrix proteins in OFs but not eyelid fibroblasts. The mechanisms involved in this enhancement mainly relied on MAPK activation. Finally, we observed that the deubiquitinase inhibitor vialinin A could down-regulate retinoic acid receptor-related orphan receptor-γt expression and decrease IL-17A level in TAO patients. CONCLUSION: Our observations illustrate the potential pathogenic role of IL-17A-producing T cells in the inflammatory response and fibrosis of TAO. The effect of vialinin A on the reduction of retinoic acid receptor-related orphan receptor-γt level implicates its potential role as a novel therapeutic agent for TAO and other autoimmune disorders in the future.

Kaempferol enhances the suppressive function of Treg cells by inhibiting FOXP3 phosphorylation.

Kaempferol is a natural flavonoid found in many vegetables and fruits. Epidemiologic studies have described that Kaempferol intake could reduce risk of cancer, especially lung, gastric, pancreatic and ovarian cancers. Recent studies have shown that Kaempferol could also be beneficial to the body to defend against inflammation, and infection by bacteria and viruses; however, the molecular mechanism of its immunoregulatory function remains largely unknown. Through screening a small molecule library of traditional Chinese medicine (TCM), we identified that Kaempferol could enhance the suppressive function of regulatory T cells (Tregs). Kaempferol was found to increase FOXP3 expression level in Treg cells and prevent pathological symptoms of collagen-induced arthritis in a rat animal model. Kaempferol could also reduce PIM1-mediated FOXP3 phosphorylation at S422. Our study reveals a molecular mechanism that underlies the anti-inflammatory action of Kaempferol for the prevention and treatment of inflammatory diseases such as rheumatoid arthritis, systemic lupus erythematosus, and ankylosing spondylitis.

Ubiquitination signals critical to regulatory T cell development and function.

Protein ubiquitination has emerged as a crucial modulator of the immune system, participating in the control of T cell differentiation, intracellular signal transduction and the induction of immune tolerance. CD4(+)CD25(+)FOXP3(+) regulatory T cells are a unique subset of cells that mediate central and peripheral immune tolerance. In this review, we highlight our current understanding of the molecular mechanisms and signaling pathways that modulate protein ubiquitination in Treg cells, and how ubiquitination determines Treg cell development and function. Understanding how FOXP3 activity is regulated by ubiquitination and deubiquitination under molecular level will promote regulatory T cell therapy for treating inflammation in autoimmune disease, infection, transplantation and cancer.

[Measurement of exhaled nitric oxide in healthy Chinese].

OBJECTIVE: To obtain the normal values of nitric oxide (NO) exhaled through nose and mouth in healthy Chinese adults by measuring exhaled NO and analyzing the influencing factors. METHODS: Eighty healthy Chinese adults were recruited, including 20 males and 60 females. The age ranged from 18 to 44 years old. Chemiluminescence analyzer (NIOX) was used to obtain the values of exhaled NO through nose and mouth. The relativity between NO and gender, age, height, body mass index, time, ambient NO were analyzed with Multiple linear regression and correlation. RESULTS: Exhaled NO values were (17+/-8)x10(-9) and correlated significantly with height. Regression equation: Y (exhaled nitric oxide)=-58.524+0.457X (height, cm), t=-2.985, P<0.01. Transnasal NO values were (819+/-211)x10(-9) and correlated significantly with age and gender. Regression equation: Y (nasal nitric oxide)=760.245+9.417X1(age)-111.222X2(gender), t=5.188, P<0.01. CONCLUSIONS: Exhaled NO normal values were 17x10(-9) and Transnasal NO normal values were 819x10(-9). Exhaled NO correlated positively with height. Transnasal NO correlated positively with age and negatively with gender.