CD45Rb-low effector T cells require IL-4 to induce IL-10 in FoxP3 Tregs and to protect mice from inflammation

IL-10-Directed Cancer Immunotherapy: Preclinical Advances, Clinical Insights, and Future Perspectives

Interleukin-10 (IL-10) is a dimeric cytokine encoded by the IL-10 gene on chromosome 1 [...].

Intestinal Tr1 Cells Confer Protection against Colitis in the Absence of Foxp3+ Regulatory T Cell-Derived IL-10

The intestinal mucosa is continually exposed to diverse microbial and dietary Ags, requiring coordinated efforts by specialized populations of regulatory T cells (Tregs) to maintain homeostasis. Suppressive mechanisms used by intestinal Tregs include the secretion of anti-inflammatory cytokines such as IL-10 and TGF-β. Defects in IL-10 signaling are associated with severe infantile enterocolitis in humans, and mice deficient in IL-10 or its receptors develop spontaneous colitis. To determine the requirement of Foxp3+ Treg-specific IL-10 for protection against colitis, we generated Foxp3-specific IL-10 knockout (KO) mice (IL-10 conditional KO [cKO] mice). Colonic Foxp3+ Tregs isolated from IL-10cKO mice showed impaired ex vivo suppressive function, although IL-10cKO mice maintained normal body weights and developed only mild inflammation over 30 wk of age (in contrast to severe colitis in global IL-10KO mice). Protection from colitis in IL-10cKO mice was associated with an expanded population of IL-10-producing type 1 Tregs (Tr1, CD4+Foxp3-) in the colonic lamina propria that produced more IL-10 on a per-cell basis compared with wild-type intestinal Tr1 cells. Collectively, our findings reveal a role for Tr1 cells in the gut, as they expand to fill a tolerogenic niche in conditions of suboptimal Foxp3+ Treg-mediated suppression and provide functional protection against experimental colitis.

The Mechanisms of Effector Th Cell Responses Contribute to Treg Cell Function: New Insights into Pathogenesis and Therapy of Asthma

CD4 ⁺ helper T (Th) cell subsets are critically involved in the pathogenesis of asthma. Naive Th cells differentiate into different subsets under the stimulation of different sets of cytokines, and the differentiation process is dominantly driven by lineage specific transcription factors, such as T-bet (Th1), GATA3 (Th2), RORγt (Th17) and Foxp3 (Treg). The differentiation mechanisms driven by these transcription factors are mutually exclusive, resulting in functional inhibition of these Th subsets to each other, particularly prominent between effector Th cells and Treg cells, such as Th2 versus Treg cells and Th17 versus Treg cells. Being of significance in maintaining immune homeostasis, the balance between effector Th cell response and Treg cell immunosuppression provides an immunological theoretical basis for us to understand the immunopathological mechanism and develop the therapy strategies of asthma. However, recent studies have found that certain factors involved in effector Th cells response, such as cytokines and master transcription factors (IL-12 and T-bet of Th1, IL-4 and GATA3 of Th2, IL-6 and RORγt of Th17), not only contribute to immune response of effector Th cells, but also promote the development and function of Treg cells, therefore bridging the interplay between effector Th cell immune responses and Treg cell immunosuppression. Although we have an abundant knowledge concerning the role of these cytokines and transcription factors in effector Th cell responses, our understanding on their role in Treg cell development and function is scattered thus need to be summarized. This review summarized the role of these cytokines and transcription factors involved in effector Th cell responses in the development and function of Treg cells, in the hope of providing new insights of understanding the immunopathological mechanism and seeking potential therapy strategies of asthma.

Antigen presenting cell response to polysaccharide A is characterized by the generation of anti-inflammatory macrophages

Polysaccharide A (PSA) is the immunodominant capsular carbohydrate from the gram negative commensal microbe Bacteroides fragilis that has shown remarkable potency in ameliorating many rodent models of inflammatory disease by eliciting downstream suppressive CD4+ T cells. PSA is composed of a zwitterionic repeating unit that allows it to be processed by antigen presenting cells (APCs) and presented by MHCII in a glycosylation-dependent manner. While previous work has uncovered much about the interactions between MHCII and PSA, as well as the downstream T cell response, little is known about how PSA affects the phenotype of MHCII+ APCs, including macrophages. Here, we utilized an unbiased systems approach consisting of RNAseq transcriptomics, high-throughput flow cytometry, Luminex analysis and targeted validation experiments to characterize the impact of PSA-mediated stimulation of splenic MHCII+ cells. The data revealed that PSA potently elicited the upregulation of an alternatively activated M2 macrophage transcriptomic and cell surface signature. Cell-type-specific validation experiments further demonstrated that PSA-exposed bone marrow-derived macrophages (BMDMs) induced cell surface and intracellular markers associated with M2 macrophages compared with conventional peptide ovalbumin (ova)-exposed BMDMs. In contrast to macrophages, we also found that CD11c+ dendritic cells (DCs) upregulated the pro-T cell activation costimulatory molecule CD86 following PSA stimulation. Consistent with the divergent BMDM and DC changes, PSA-exposed DCs elicited an antigen-experienced T cell phenotype in co-cultures, whereas macrophages did not. These findings collectively demonstrate that the PSA-induced immune response is characterized by both T cell stimulation via presentation by DCs, and a previously unrecognized anti-inflammatory polarization of macrophages.

Integration of IL-2 and IL-4 signals coordinates divergent regulatory T cell responses and drives therapeutic efficacy

Cells exist within complex milieus of communicating factors, such as cytokines, that combine to generate context-specific responses, yet nearly all knowledge about the function of each cytokine and the signaling propagated downstream of their recognition is based on the response to individual cytokines. Here, we found that regulatory T cells (Tregs) integrate concurrent signaling initiated by IL-2 and IL-4 to generate a response divergent from the sum of the two pathways in isolation. IL-4 stimulation of STAT6 phosphorylation was blocked by IL-2, while IL-2 and IL-4 synergized to enhance STAT5 phosphorylation, IL-10 production, and the selective proliferation of IL-10-producing Tregs, leading to increased inhibition of conventional T cell activation and the reversal of asthma and multiple sclerosis in mice. These data define a mechanism of combinatorial cytokine signaling and lay the foundation upon which to better understand the origins of cytokine pleiotropy while informing improved the clinical use of cytokines.

Characterization of Polysaccharide A Response Reveals Interferon Responsive Gene Signature and Immunomodulatory Marker Expression

Polysaccharide A (PSA), a capsular carbohydrate from the commensal gut bacteria Bacteroides fragilis, has been shown to possess both potent T cell-dependent pro- and anti-inflammatory properties. PSA is able to induce abscess and adhesion formation in sepsis models, but can also inhibit asthma, inflammatory bowel disease (IBD) and experimental autoimmune encephalomyelitis (EAE) through MHCII-dependent activation of CD4+ T cells. Yet, despite decades of study, the ability of PSA to balance both these pro- and anti-inflammatory responses remains poorly understood. Here, we utilized an unbiased systems immunology approach consisting of RNAseq transcriptomics, high-throughput flow cytometry, and Luminex analysis to characterize the full impact of PSA-mediated stimulation of CD4+ T cells. We found that exposure to PSA resulted in the upregulation and secretion of IFNγ, TNFα, IL-6, and CXCL10, consistent with an interferon responsive gene (IRG) signature. Importantly, PSA stimulation also led to expression of immune checkpoint markers Lag3, Tim3, and, especially, PD1, which were also enriched and sustained in the gut associated lymphoid tissue of PSA-exposed mice. Taken together, PSA responding cells display an unusual mixture of pro-inflammatory cytokines and anti-inflammatory surface receptors, consistent with the ability to both cause and inhibit inflammatory disease.

Molecular Markers of Regulatory T Cells in Cancer Immunotherapy with Special Focus on Acute Myeloid Leukemia (AML) - A Systematic Review

The next-generation immunotherapy can only be effective if researchers have an in-depth understanding of the function and regulation of Treg cells in antitumor immunity combined with the discovery of new immunity targets. This can enhance clinical efficacy of future and novel therapies and reduces any adverse reactions arising from the latter. This review discusses tumor treatment strategies using regulatory T (Treg) cell therapy in a Tumor Microenvironment (TME). It also discusses factors affecting TME instability as well as relevant treatments to prevent future immune disorders. It is prognosticated that PD-1 inhibitors are risky and their adverse effects should be taken into account when they are administered to treat Acute Myeloid Leukemia (AML), lung adenocarcinoma, and prostate adenocarcinoma. In contrast, Treg molecular markers FoxP3 and CD25 analyzed here have stronger expression in almost all kinds of cancers compared with normal people. However, CD25 inhibitors are more effective compared to FoxP3 inhibitors, especially in combination with TGF-β blockade, in predicting patient survival. According to the data obtained from the Cancer Genome Atlas, we then concentrate on AML immunotherapy and discuss different therapeutic strategies including anti-CD25/IL-2, anti-CTLA-4, anti-IDO, antityrosine kinase receptor, and anti-PI3K therapies and highlight the recent advances and clinical achievements in AML immunotherapy. In order to prognosticate the risk and adverse effects of key target inhibitors (namely against CTLA-4, FoxP3, CD25, and PD-1), we finally analyzed and compared the Cancer Genome Atlas derived from ten common cancers. This review shows that Treg cells are strongly increased in AML and the comparative review of key markers shows that Tregbased immunotherapy is not effective for all kinds of cancer. Therefore, blocking CD25(+)FoxP3(+) Treg cells is suggested in AML more than other kinds of cancer; meanwhile, Treg markers studied in other cancers have also great lessons for AML immunotherapy.

Wogonin Suppresses IL-10 Production in B Cells via STAT3 and ERK Signaling Pathway

Wogonin (5,7-dihydroxy-8-methoxyflavone) is an ingredient of the extracts from Scutellaria baicalensis, which has documented a wide spectrum of anti-inflammatory and antitumor activities, including inhibiting regulatory T cells, regulating effector T cell functions, and mediating macrophage immunity. However, the potential effect of Wogonin on B cells has not been fully understood. Here, our results showed that Wogonin inhibited IL-10 secretion in B cells. When purified B cells were activated by lipopolysaccharide (LPS) in vitro, the amount of IL-10 production in supernatant was decreased by Wogonin significantly. The protective role of B cells on dextran sulfate sodium- (DSS-) induced colitis was alleviated after exposure to Wogonin. Furthermore, administration of Wogonin on LPS-treated B cells suppressed phosphorylation of STAT3 and ERK, but not AKT. Interestingly, among those IL-10 signaling-associated transcription factors, mRNA and protein levels of Hif-1α were specifically decreased by Wogonin. Overall, our study indicates that Wogonin suppresses potentially IL-10 production in B cells via inhibition of the STAT3 and ERK signaling pathway as well as inhibition of mRNA and protein levels of the transcription factor Hif-1α. These results provide novel and potential molecular targets of Wogonin in B cells and help us further understand its mechanism of action, which could potentially improve its clinical application in the future.

Disruption of hepatocyte Sialylation drives a T cell-dependent pro-inflammatory immune tone

Through the catalysis of α2,6-linked sialylation, the enzyme ST6Gal1 is thought to play key roles in immune cell communication and homeostasis. Of particular importance, glycans with terminal α2,6-sialic acids are known to negatively regulate B cell receptor signaling and are associated with an immunosuppressive tumor microenvironment that promotes T cell anergy, suggesting that α2,6-sialic acids are a key immune inhibitory signal. Consistent with this model, mice harboring a hepatocyte-specific ablation of ST6Gal1 (H-cKO) develop a progressive and severe non-alcoholic fatty liver disease characterized by steatohepatitis. Using this H-cKO mouse, we have further discovered that loss of hepatocyte α2,6-sialylation not only increases the inflammatory state of the local tissue microenvironment, but also systemic T cell-dependent immune responses. H-cKO mice responded normally to innate and passively induced inflammation, but showed significantly increased morbidity in T cell-dependent house dust mite-antigen (HDM)-induced asthma and myelin oligodendrocyte glycoprotein (MOG) peptide-induced experimental autoimmune encephalomyelitis (EAE). We further discovered that H-cKO mice have a profound shift toward effector/memory T cells even among unchallenged mice, and that macrophages from both the liver and spleen expressed the inhibitory and α2,6-sialic acid-specific glycan binding molecule CD22. These findings align with previously reported pro-inflammatory changes in liver macrophages, and support a model in which the liver microenvironment sets a systemic immune tone that is regulated by tissue α2,6-sialylation and mediated by liver macrophages and systemic T cells.

Th1, Th2, and Th17 cytokines in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the breakdown of immune tolerance leading to excessive inflammation and tissue damage. Imbalance in the levels of cytokines represents one of the multifactorial causes of SLE pathogenesis and it contributes to disease severity. Deregulated levels of T helper type 1 (Th1), type 2 (Th2), and type 17 (Th17) cytokines have been associated with autoimmune inflammation. Growing evidence has shown deregulated levels of Th1, Th2, and Th17 cytokines in SLE patients compared to healthy controls associated with disease activity and severity. In this review, we describe and discuss the levels of Th1, Th2, and Th17 cytokines in SLE patients, and clinical trials involving Th1, Th2, and Th17 cytokines in SLE patients. In particular, with the exception of IL-2, IL-4, and TGF-β1, the levels of Th1, Th2, and Th17 cytokines are increased in SLE patients associated with disease severity. Current phase II or III studies involve therapeutic antibodies targeting IFN-α and type I IFN receptor, while low-dose IL-2 therapy is assessed in phase II clinical trials.