Plasticity is the differentiated state of CD4 T cells

The Plasticity of Immune Cell Response Complicates Dissecting the Underlying Pathology of Multiple Sclerosis

Multiple sclerosis (MS) is a neurodegenerative autoimmune disease characterized by the destruction of the myelin sheath of the neuronal axon in the central nervous system. Many risk factors, including environmental, epigenetic, genetic, and lifestyle factors, are responsible for the development of MS. It has long been thought that only adaptive immune cells, especially autoreactive T cells, are responsible for the pathophysiology; however, recent evidence has indicated that innate immune cells are also highly involved in disease initiation and progression. Here, we compile the available data regarding the role immune cells play in MS, drawn from both human and animal research. While T and B lymphocytes, chiefly enhance MS pathology, regulatory T cells (Tregs) may serve a more protective role, as can B cells, depending on context and location. Cells chiefly involved in innate immunity, including macrophages, microglia, astrocytes, dendritic cells, natural killer (NK) cells, eosinophils, and mast cells, play varied roles. In addition, there is evidence regarding the involvement of innate-like immune cells, such as γδ T cells, NKT cells, MAIT cells, and innate-like B cells as crucial contributors to MS pathophysiology. It is unclear which of these cell subsets are involved in the onset or progression of disease or in protective mechanisms due to their plastic nature, which can change their properties and functions depending on microenvironmental exposure and the response of neural networks in damage control. This highlights the need for a multipronged approach, combining stringently designed clinical data with carefully controlled in vitro and in vivo research findings, to identify the underlying mechanisms so that more effective therapeutics can be developed.

Poly-functional T helper cells in human tonsillar mononuclear cells

Tonsils are important lymphoid organs in which B cells and T cells complete their maturation and identify cells that are infected by pathogens. However, the functions of T cells in human tonsils remain unclear, especially the characteristics of polyfunctional CD4+ T helper cells. In this study, we used multi-color flow cytometry to analyze the expression or co-expression of effector cytokines in CD4+ T cells from tonsillar tissues. We have demonstrated that tonsillar CD4+ T cell can express various Th effector cytokines after short-term polyclonal stimulation, and that cytokine-producing CD4+ T cells were CD45RO+ T cells. In addition, we analyzed the co-expression of two or more kinds of cytokines at the level of a single cell. The results showed that tonsillar CD4+ T cells exhibited polyfunctionality by co-expressing two to five kinds of cytokines in the same time. These data furnished a basic theory for further understanding the differentiation of polyfunctional Th cells in human tonsils and their functions in resisting invasive microorganisms.

Crotoxin Isolated from Crotalus durissus terrificus Venom Modulates the Functional Activity of Dendritic Cells via Formyl Peptide Receptors

The Crotalus durissus terrificus rattlesnake venom, its main toxin, crotoxin (CTX), and its crotapotin (CA) and phospholipase A₂ (CB) subunits modulate the immune system. Formyl peptide receptors (FPRs) and lipoxin A₄ (LXA₄) are involved in CTX's effect on macrophages and neutrophils. Dendritic cells (DCs) are plasticity cells involved in the induction of adaptive immunity and tolerance maintenance. Therefore, we evaluated the effect of CTX, CA or CB on the maturation of DCs derived from murine bone marrow (BM). According to data, CTX and CB-but not CA-induced an increase of MHC-II, but not costimulatory molecules on DCs. Furthermore, CTX and CB inhibited the expression of costimulatory and MHC-II molecules, secretion of proinflammatory cytokines and NF-κBp65 and p38/ERK1/2-MAPK signaling pathways by LPS-incubated DCs. Differently, CTX and CB induced IL-10, PGE₂ and LXA₄ secretion in LPS-incubated DCs. Lower proliferation and IL-2 secretion were verified in coculture of CD3⁺ cells and DCs incubated with LPS plus CTX or CB compared with LPS-incubated DCs. The effect of CTX and CB on DCs was abolished in cultures incubated with a FPRs antagonist. Hence, CTX and CB exert a modulation on functional activity of DCs; we also checked the involvement the FPR family on cell activities.

Characteristics of Schistosoma japonicum infection induced IFN-γ and IL-4 co-expressing plasticity Th cells

Schistosoma japonicum infection can induce granulomatous inflammation and cause tissue damage in the mouse liver. The cytokine secretion profile of T helper (Th) cells depends on both the nature of the activating stimulus and the local microenvironment (e.g. cytokines and other soluble factors). In the present study, we found an accumulation of large numbers of IFN-γ(+)  IL-4(+)  CD4(+) T cells in mouse livers. This IFN-γ(+)  IL-4(+) cell population increased from 0·68 ± 0·57% in uninfected mice to 7·05 ± 3·0% by week 4 following infection and to 9·6 ± 5·28% by week 6, before decreasing to 6·3 ± 5·9% by week 8 in CD4 T cells. Moreover, IFN-γ(+)  IL-4(+) Th cells were also found in mouse spleen and mesenteric lymph nodes 6 weeks after infection. The majority of the IFN-γ(+)  IL-4(+) Th cells were thought to be related to a state of immune activation, and some were memory T cells. Moreover, we found that these S. japonicum infection-induced IFN-γ(+)  IL-4(+) cells could express interleukin-2 (IL-2), IL-9, IL-17 and high IL-10 levels at 6 weeks after S. japonicum infection. Taken together, our data suggest the existence of a population of IFN-γ(+)  IL-4(+) plasticity effector/memory Th cells following S. japonicum infection in C57BL/6 mice.

IL-12 induced the generation of IL-21- and IFN-γ-co-expressing poly-functional CD4+ T cells from human naive CD4+ T cells

Interleukine-12 is critical for the differentiation of Th1 cells and can improve the development of Th1 cells with Tfh cell features in mouse model. Human effector CD4(+) T cells also exhibit poly-functionality by co-expressing IL-21 and IFN-γ. However, the effects of IL-12 on regulating generation of human IL-21- and IFN-γ-expressing CD4(+) T cells are still incompletely understood. Our studies found that IL-12 but not IL-21 could induce the differentiation of human naive CD4(+) T cells into multi-cytokine expressing CD4(+) T cells in vitro, which co-expressed IL-21 and IFN-γ with or without IL-2 and TNF-α. At early stage of differentiation, addition of excess exogenous IFN-γ could increase the generation of IL-21- and IFN-γ-expressing CD4(+) T cells, furthermore, anti-IFN-γ depressed the percentage of poly-functional CD4(+) T cells. Phenotypically, IL-21(+)IFN-γ(+)CD4(+) T cells exhibited more characteristic features about both of Th1 and Tfh cells than IL-21 or IFN-γ single-expressing CD4(+) T cells. Mechamistically, IL-12 modulated the differentiation of IL-21(+)IFN-γ(+)CD4(+) T cells from naive CD4(+) T cells via the pathways of STAT-1/4, T-bet and BCL(-)6. Different from naive CD4(+) T cells, IL-12 increasing the generation of IL-21(+)IFN-γ(+)CD4(+) T cells from memory CD4(+) T cells was only involved in STAT-4 pathway but not STAT-1. Poly-functional CD4(+) T cells were contributed to generation and progress of varies diseases and our studies provide basic theoretics for the designs of vaccine and therapies of diseases.

Dendritic cells treated with crude Plasmodium berghei extracts acquire immune-modulatory properties and suppress the development of autoimmune neuroinflammation

Dendritic cells (DCs) are professional antigen-presenting cells specifically targeted during Plasmodium infection. Upon infection, DCs show impaired antigen presentation and T-cell activation abilities. In this study, we aimed to evaluate whether cellular extracts obtained from Plasmodium berghei-infected erythrocytes (PbX) modulate DCs phenotypically and functionally and the potential therapeutic usage of PbX-modulated DCs in the control of experimental autoimmune encephalomyelitis (EAE, the mouse model for human multiple sclerosis). We found that PbX-treated DCs have impaired maturation and stimulated the generation of regulatory T cells when cultured with naive T lymphocytes in vitro. When adoptively transferred to C57BL/6 mice the EAE severity was reduced. Disease amelioration correlated with a diminished infiltration of cytokine-producing T cells in the central nervous system as well as the suppression of encephalitogenic T cells. Our study shows that extracts obtained from P. berghei-infected erythrocytes modulate DCs towards an immunosuppressive phenotype. In addition, the adoptive transfer of PbX-modulated DCs was able to ameliorate EAE development through the suppression of specific cellular immune responses towards neuro-antigens. To our knowledge, this is the first study to present evidence that DCs treated with P. berghei extracts are able to control autoimmune neuroinflammation.