Pro-inflammatory human Th17 cells selectively express P-glycoprotein and are refractory to glucocorticoids

Transcriptional profile of tuberculosis antigen-specific T cells reveals novel multifunctional features

In latent tuberculosis infection (LTBI) spread of the bacteria is contained by a persistent immune response, which includes CD4(+) T cells as important contributors. In this study we show that TB-specific CD4(+) T cells have a characteristic chemokine expression signature (CCR6(+)CXCR3(+)CCR4(-)), and that the overall number of these cells is significantly increased in LTBI donors compared with healthy subjects. We have comprehensively characterized the transcriptional signature of CCR6(+)CXCR3(+)CCR4(-) cells and found significant differences to conventional Th1, Th17, and Th2 cells, but no major changes between healthy and LTBI donors. CCR6(+)CXCR3(+)CCR4(-) cells display lineage-specific signatures of both Th1 and Th17 cells, but also have a unique gene expression program, including genes associated with susceptibility to TB, enhanced T cell activation, enhanced cell survival, and induction of a cytotoxic program akin to CTL cells. Overall, the gene expression signature of CCR6(+)CXCR3(+)CCR4(-) cells reveals characteristics important for controlling latent TB infections.

TH17 cells in human recurrent pregnancy loss and pre-eclampsia

T helper 17 (TH17) cells have been identified as a new lineage of helper T cells and have been shown to be important in host defense against extracellular infectious agents, autoimmune disease and chronic inflammatory diseases. Recently, TH17 cells have also been shown to participate in successful pregnancy, as well as in the pathogenesis of diseases of pregnancy, such as recurrent spontaneous abortion (RSA) and pre-eclampsia (PE). Here, we review our current knowledge of TH17 cells in human RSA and PE. We also discuss how the local uterine microenvironment affects the differentiation of TH17 cells and the mechanisms that regulate TH17 cells during pregnancy. Research into TH17 cells will not only advance our understanding of TH17-related pregnancy complications, but will also facilitate the design of novel therapies for reproductive diseases.

IL-1β promotes the differentiation of polyfunctional human CCR6+CXCR3+ Th1/17 cells that are specific for pathogenic and commensal microbes

In humans, Th1/17 cells, identified by coexpression of the chemokine receptors CCR6 and CXCR3, are proposed to be highly pathogenic in several autoimmune disorders due in part to their expression of the proinflammatory cytokines IL-17, IFN-γ, and GM-CSF. However, their developmental requirements, relationship with "classic" Th17 and Th1 cells and physiological role in normal immune responses are not well understood. In this study, we examined CCR6+ CXCR3+ Th1/17 cells from healthy individuals and found that ex vivo these cells produced the effector cytokines IL-17, IL-22, and IFN-γ in all possible combinations and were highly responsive to both IL-12 and IL-23. Moreover, although the Ag specificity of CCR6+ CXCR3+ Th1/17 cells showed substantial overlap with that of Th1 and Th17 cells, this population was enriched in cells recognizing certain extracellular bacteria and expressing the intestinal homing receptor integrin β7. Finally, we identified IL-1β as a key cytokine that renders Th17 cells sensitive to IL-12, and both cytokines together potently induced the differentiation of cells that produce IL-17, IFN-γ, and GM-CSF. Therefore, interfering with IL-1β and IL-12 signaling in Th17 cells during inflammation may be a promising therapeutic approach to reduce their differentiation into "pathogenic" CCR6+ CXCR3+ Th1/17 cells in patients with autoimmune diseases.

The role of the IL-22/IL-22R1 axis in cancer

Interleukin-22 (IL-22) is an IL-10 family cytokine produced by T cells and innate lymphoid cells. The IL-22 signaling pathway orchestrates mucosal immune defense and tissue regeneration through pleiotropic effects including pro-survival signaling, cell migration, dysplasia and angiogenesis. While these functions can prevent initial establishment of tumors, they can also be hijacked by aggressive cancers to enhance tumor growth and metastasis. Thus, the role of the IL-22/IL-22R1 axis in cancer is complex and context-specific. Evidence of IL-22 involvement manifests as dysregulation of IL-22 expression and signaling in patients with many common cancers including those of the gut, skin, lung and liver. Unlike other cancer-associated cytokines, IL-22 has restricted tissue specificity as its unique receptor IL-22R1 is exclusively expressed on epithelial and tissue cells, but not immune cells. This makes it an attractive target for therapy as there is potential achieve anti-tumor immunity with fewer side effects. This review summarizes current findings on functions of IL-22 in association with general mechanisms for tumorigenesis as well as specific contributions to particular cancers, and ponders how best to approach further research in the field.

Leishmania braziliensis amastigotes stimulate production of IL-1β, IL-6, IL-10 and TGF-β by peripheral blood mononuclear cells from nonendemic area healthy residents

Leishmania (Viannia) braziliensis causes cutaneous and mucosal leishmaniasis in several countries in Latin America. In mammals, the parasites live as amastigotes, interacting with host immune cells and stimulating cytokine production that will drive the type of the specific immune responses. Generation of Th17 lymphocytes is associated with tissue destruction and depends on IL-1β, IL-6, TGF-β and IL-23 production, whereas IL-10 and TGF-β are associated with tissue protection. Here, we evaluate whether amastigotes stimulate peripheral blood mononuclear cells (PBMCs) from healthy donors to produce the major cytokines responsible for the generation of Th17. Seven L. (V.) braziliensis isolates from patients with different clinical forms of leishmaniasis were expanded in interferon-γ knockout mice to obtain amastigotes and in culture to get promastigotes. The parasites were used to stimulate PBMCs from healthy donors, and cytokine production was evaluated by ELISA or qPCR. Amastigotes and promastigotes induced IL-10 production in PBMCs; however, only amastigotes induced IL-1β, IL-6 and TGF-β. These data demonstrate for the first time that L. (V.) braziliensis amastigotes directly stimulate production of a unique pattern of cytokines that could contribute to the generation of Th17.

Autoimmune and autoinflammatory mechanisms in uveitis

The eye, as currently viewed, is neither immunologically ignorant nor sequestered from the systemic environment. The eye utilises distinct immunoregulatory mechanisms to preserve tissue and cellular function in the face of immune-mediated insult; clinically, inflammation following such an insult is termed uveitis. The intra-ocular inflammation in uveitis may be clinically obvious as a result of infection (e.g. toxoplasma, herpes), but in the main infection, if any, remains covert. We now recognise that healthy tissues including the retina have regulatory mechanisms imparted by control of myeloid cells through receptors (e.g. CD200R) and soluble inhibitory factors (e.g. alpha-MSH), regulation of the blood retinal barrier, and active immune surveillance. Once homoeostasis has been disrupted and inflammation ensues, the mechanisms to regulate inflammation, including T cell apoptosis, generation of T_reg cells, and myeloid cell suppression in situ, are less successful. Why inflammation becomes persistent remains unknown, but extrapolating from animal models, possibilities include differential trafficking of T cells from the retina, residency of CD8⁺ T cells, and alterations of myeloid cell phenotype and function. Translating lessons learned from animal models to humans has been helped by system biology approaches and informatics, which suggest that diseased animals and people share similar changes in T cell phenotypes and monocyte function to date. Together the data infer a possible cryptic infectious drive in uveitis that unlocks and drives persistent autoimmune responses, or promotes further innate immune responses. Thus there may be many mechanisms in common with those observed in autoinflammatory disorders.

Reprogramming antitumor immunity

Regenerative medicine holds great promise in replacing tissues and organs lost to degenerative disease and injury. Application of the principles of cellular reprogramming for the treatment of cancer, however, is not well established. Here, we present an overview of cellular reprogramming techniques used in regenerative medicine, and within this context, envision how the scope of regenerative medicine may be expanded to treat metastatic cancer by revitalizing an exhausted and senescent immune system.

P-glycoprotein and drug resistance in systemic autoimmune diseases

Autoimmune diseases such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and psoriatic arthritis (PsA) are chronic inflammatory disorders of unknown etiology characterized by a wide range of abnormalities of the immune system that may compromise the function of several organs, such as kidney, heart, joints, brain and skin. Corticosteroids (CCS), synthetic and biologic immunosuppressive agents have demonstrated the capacity to improve the course of autoimmune diseases. However, a significant number of patients do not respond or develop resistance to these therapies over time. P-glycoprotein (P-gp) is a transmembrane protein that pumps several drugs out of the cell, including CCS and immunosuppressants; thus, its over-expression or hyper-function has been proposed as a possible mechanism of drug resistance in patients with autoimmune disorders. Recently, different authors have demonstrated that P-gp inhibitors, such as cyclosporine A (CsA) and its analogue Tacrolimus, are able to reduce P-gp expression and or function in SLE, RA and PsA patients. These observations suggest that P-gp antagonists could be adopted to revert drug resistance and improve disease outcome. The complex inter-relationship among drug resistance, P-gp expression and autoimmunity still remains elusive.