Characterizations of CD4-1, CD4-2 and CD8β T cell subpopulations in peripheral blood leucocytes,spleen and head kidney of Japanese flounder (Paralichthys olivaceus)

In the previous study, antibodies against CD3 molecule have been produced and were used in labeling T cells in Japanese flounder (Paralichthys olivaceus). In this paper, CD4⁺ and CD8⁺ lymphocytes subpopulations in peripheral blood leucocytes (PBL), spleen and head kidney of flounder were investigated. The flounder CD4-1, CD4-2 and CD8β recombinant proteins and their antibodies (Abs) were produced, then the cross-reactivity of the Abs to CD4-1, CD4-2 and CD8β was detected by Western blotting, respectively, and the reactions of Abs to PBL were analyzed by immunofluorescence staining (IFS) and flow cytometry (FCM). CD4-1⁺/CD3⁺, CD4-2⁺/CD3⁺, and CD8β⁺/CD3⁺ lymphocytes in PBL, spleen and head kidney were observed by double IFS, then their proportions were analyzed using two-color FCM, respectively. Further, CD4-1/CD8β, CD4-2/CD8β, or CD4-1/CD4-2 lymphocytes were analyzed using double-IFS and two-color FCM. Finally, CD4-1⁺, CD4-2⁺, and CD8β⁺ lymphocytes in spleen and head kidney were observed by immunohistochemistry. The results showed that the Abs were specific for CD4-1, CD4-2 and CD8β molecules, respectively. The proportions of CD4-1⁺/CD3⁺, CD4-2⁺/CD3⁺, and CD8β⁺/CD3⁺ lymphocytes were 6.7 ± 2.0%, 8.6 ± 2.8%, 2.1 ± 1.3% in PBL; 13.6 ± 3.6%, 15.6 ± 5.2%, 2.8 ± 1.4% in spleen; 20.0 ± 4.6%, 20.5 ± 4.6%, 3.2 ± 1.5% in head kidney, respectively. Most CD4⁺ and CD8⁺ cell subpopulations belonged to CD3⁺ cells; there were no cross-reactivity between CD4⁺ and CD8⁺ cells. CD4-1⁺/CD4-2⁻, CD4-1⁻/CD4-2⁺, and CD4-1⁺/CD4-2⁺ cells presented different proportions in PBL, spleen and head kidney, among them, CD4-1⁺/CD4-2⁺ cell is the majority of CD4T cell subpopulation.     

Aberrant NKG2D expression with IL-17 production of CD4+ T subsets in patients with type 2 diabetes

Type 2 diabetes (T2D) is a systemic inflammatory disease. Although the natural killer group 2, member D (NKG2D) receptor, was not expressed normally on CD4+ T cells, the aberrant expression was found in pathological conditions such as in auto-immune diseases. However, the involvement of NKG2D in pathogenesis of T2D is unclear. We hypothesize that there is an inflammatory CD4+ T cell subpopulation expressing NKG2D and producing interleukin (IL)-17 in T2D. NKG2D expression on CD4+ T cells and their subsets were analyzed by multi-color staining using flow cytometry. Lymphocytes were activated by phorbol-12-myristate-13-acetate (PMA) and ionomycin, and were stained for intracellular IL-17. To investigate the mechanism of IL-17 production, patients’ lymphocytes were stimulated using specific anti-T cell receptor (TCR) alone, anti-NKG2D alone or a combination of the two antibodies. CD4+ T cells and particularly, CD4 + CD28^null T subset of T2D patients were highly expressed NKG2D and more prevalent compared to non-diabetic individuals (ND) (P = 0.039 and P = 0.022, respectively). Significantly higher percentages of CD4 + CD28^nullNKG2D + T cells of patients produced IL-17 when compared to those of ND (P = 0.024) and were positively correlated with the level of glycated hemoglobin A1c (HbA1c) (R² = 0.386, P = 0.041). Additionally, this cell population could be stimulated by specific monoclonal anti-NKG2D to produce IL-17. In conclusion, CD4 + CD28^nullNKG2D+ T cells were expanded in T2D, especially in patients with poor glycemic control. NKG2D may be one of the surrogate co-stimulatory receptors leading to irregular inflammatory function producing IL-17. An IL-17 producing CD4 + CD28^nullNKG2D + T cells may potentially be involved in pathogenesis and drive severity of the disease with the glycemic dependence. This particular cell type could be targeted for prognostic or therapeutic purposes.     

Preterm cord blood CD4+ T cells exhibit increased IL-6 production in chorioamnionitis and decreased CD4+ T cells in bronchopulmonary dysplasia

BackgroundChorioamnionitis (CA) is associated with premature delivery and bronchopulmonary dysplasia (BPD). We hypothesize that preterm infants exposed to CA have reduced suppressive regulatory T cells (Treg) and increased non-regulatory T cell pro-inflammatory cytokines, increasing risk for BPD.ObjectiveTo evaluate cord blood CD4⁺ T cell regulatory phenotype and pro-inflammatory cytokine production in CA and BPD groups.Study designCord blood mononuclear cells from infants (GA ⩽32 weeks), with or without placental histological evidence of CA (hChorio), were analyzed by flow cytometry. Clinical information was collected by retrospective chart review. Numbers of putative Treg (CD4⁺FoxP3⁺CD25⁺CD127Dim), CD4⁺ non-Tregs, and CD4⁺ T cell intracellular cytokine content following in vitro stimulation were compared with CA status and oxygen requirement at 36 weeks postmenstrual age.ResultAbsolute Treg numbers were not different in CA and non-CA exposed samples. However, the infants who developed BPD had a significant decrease in Treg and non-regulatory T cell numbers. Greater IL-6 production was observed in hCA group.ConclusionA pro-inflammatory CD4⁺ T cell status is noted in CA and BPD but the later disease is also associated with decrease in Tregs, suggesting that the development of BPD is marked by distinct inflammatory changes from those of CA exposed infants.     

AT1 receptor-mediated angiotensin II activation and chemotaxis of T lymphocytes

Angiotensin II (Ang II), a central renin–angiotensin system (RAS) effector molecule, and its receptors, AT₁ and AT₂, have been shown to be involved in the inflammatory aspects of different diseases, however the cellular mechanisms underlying the regulation of immunity are not fully understood. In this work, using spleen-derived CD4⁺ and CD8⁺ T lymphocytes activated in vitro, we tested the influence of Ang II on different aspects of the T cell function, such as activation and adhesion/transmigration through endothelial basal membrane proteins. The addition of 10⁻⁸ M Ang II did not change any of the parameters evaluated. However, 10⁻⁶ M losartan, an AT₁ receptor antagonist: (i) reduced the percentage of CD25⁺ and CD69⁺ cells of both subsets; (ii) inhibited adhesion of these cells to fibronectin or laminin by 53% or 76%, respectively and (iii) significantly reduced transmigration through fibronectin or laminin by 57% or 43%, respectively. In addition, 10⁻⁶ M captopril, an angiotensin-converting enzyme inhibitor had similar effects to Ang II, however its effects were reverted by exogenous Ang II (10⁻⁸ M). None of these responses was modified by 10⁻⁷ M PD123319, an AT₂ antagonist. These data reinforce the notion of endogenous production of Ang II by T cells, which is important for T cell activation, and adhesion/transmigration induced on interaction with basal membrane proteins, possibly involving AT₁ receptor activation. Moreover, AT₁ receptor expression is 10-fold higher in activated T lymphocytes compared with naive cells, but AT₂ receptor expression did not change after T cell receptor triggering.     

High expression of OX40 (CD134) and 4-1BB (CD137) molecules on CD4+CD25high cells in children with type 1 diabetes

PurposeDespite the rapidly rising incidence of diabetes in children, with the highest rise in children < 5 years of age, data on mechanisms that trigger severe beta-cells damage are limited. The aim of the study was to assess the frequency of OX40 (CD134) or 4-1BB (CD137) positive cells in the peripheral blood of children with newly diagnosed type 1 diabetes (T1D) in comparison to healthy controls.Material/methodsThe study included 33 children (mean age 7.3 ± 5.4 years) with newly diagnosed T1D and 39 age-matched healthy controls. Separate analysis was performed in children < 5 years. Flow cytometric analysis was performed using the following markers: CD4, CD25, CD137, and CD134. Fasting C-peptide level was assessed as well.ResultsThe frequency of CD4⁺CD25^highOX40⁺ was higher in T1D children than in controls (median value 3.58% vs. 1.1%, respectively; p = 0.003). Moreover, T1D children had higher frequency of CD4⁺CD25^high4-1BB⁺ cells than healthy subjects (median value 5.76% vs. 3.74%, respectively; p = 0.037). A significant correlation was noted between the age of diabetic children and the C-peptide level (r = 0.54, 95% CI [0.19–0.77], p = 0.004). In comparison with age-matched controls, children < 5 years had higher frequency of CD4⁺CD25^highOX40⁺ (p = 0.004) and CD4⁺CD25^high4-1BB⁺ cells (p = 0.079).ConclusionsOur study showed higher frequency of both OX40 and 4-1BB positive cells in T1D children in comparison to controls. It seems that observed differences might be more pronounced in children < 5 years of age than in older subjects. Further clinical studies are needed to determine the age-related differences in the immune system, in the pathogenesis of T1D.     

Neem leaf glycoprotein promotes dual generation of central and effector memory CD8+ T cells against sarcoma antigen vaccine to induce protective anti-tumor immunity

We have previously shown that Neem Leaf Glycoprotein (NLGP) mediates sustained tumor protection by activating host immune response. Now we report that adjuvant help from NLGP predominantly generates CD44⁺CD62L^highCCR7^high central memory (TCM; in lymph node) and CD44⁺CD62L^lowCCR7^low effector memory (TEM; in spleen) CD8⁺ T cells of Swiss mice after vaccination with sarcoma antigen (SarAg). Generated TCM and TEM participated either to replenish memory cell pool for sustained disease free states or in rapid tumor eradication respectively. TCM generated after SarAg + NLGP vaccination underwent significant proliferation and IL-2 secretion following SarAg re-stimulation. Furthermore, SarAg + NLGP vaccination helps in greater survival of the memory precursor effector cells at the peak of the effector response and their maintenance as mature memory cells, in comparison to single modality treatment. Such response is corroborated with the reduced phosphorylation of FOXO in the cytosol and increased KLF2 in the nucleus associated with enhanced CD62L, CCR7 expression of lymph node-resident CD8⁺ T cells. However, spleen-resident CD8⁺ T memory cells show superior efficacy for immediate memory-to-effector cell conversion. The data support in all aspects that SarAg + NLGP demonstrate superiority than SarAg vaccination alone that benefits the host by rapid effector functions whenever required, whereas, central-memory cells are thought to replenish the memory cell pool for ultimate sustained disease free survival till 60 days following post-vaccination tumor inoculation.     

Defective integration of activating signals derived from the T cell receptor (TCR) and costimulatory molecules in both CD4+ and CD8+ T lymphocytes of common variable immunodeficiency (CVID) patients

CVID is characterized by hypogammaglobulinaemia and impaired antibody production. Previous studies demonstrated defects at the T cell level. In the present study the response of purified CD4⁺ and CD8⁺ T lymphocytes to stimulation with anti-TCR monoclonal antibody (the first signal) in combination with anti-CD4 or anti-CD8, anti-CD2 and anti-CD28 MoAbs (the costimulatory signals) was investigated. Both CD4⁺ and CD8⁺ T cells from the patients showed significantly reduced IL-2 release following stimulation via TCR and costimulation via CD4 or CD8 and CD2, respectively. However, normal IL-2 production following TCR plus phorbol myristate acetate (PMA) costimulation and normal expression of an early activation marker, CD69, after TCR + CD28 stimulation indicated that TCR was able to transduce a signal. Furthermore, both IL-2 and IL-4 release were impaired in CD4⁺ lymphocytes following TCR + CD28 stimulation. In addition, stimulation via TCR + CD28 resulted in significantly decreased expression of CD40 ligand in the patients. These results suggest that the integration of activating signals derived from the TCR and costimulatory molecules is defective in CVID patients; the defect is not confined to costimulation via a single molecule, or restricted to cells producing Thl-type cytokines such as IL-2, and is expressed in both CD4⁺ and CD8⁺T cell subsets.     

Identification of a CD4+ T cell line with Treg-like activity

Regulatory T cells (Tregs) suppress adaptive immunity and inflammation. Although they play a role in suppressing anti-tumor responses, development of therapeutics that target Tregs is limited by their low abundance, heterogeneity, and lack of specific cell surface markers. We isolated human PBMC-derived CD4⁺ CD25^high Foxp3⁺ Tregs and demonstrate they suppress stimulated CD4⁺ PBMCs in a cell contact-dependent manner. Because it is not possible to functionally characterize cells after intracellular Foxp3 staining, we identified a human T cell line, MoT, as a model of human Foxp3⁺ Tregs. Unlike Jurkat T cells, MoT cells share common surface markers consistent with human PBMC-derived Tregs such as: CD4, CD25, GITR, LAG-3, PD-L1, CCR4. PBMC-derived Tregs and MoT cells, but not Jurkat cells, inhibited proliferation of human CD4⁺ PBMCs in a ratio-dependent manner. Transwell membrane separation prevented suppression of stimulated CD4⁺ PBMC proliferation by MoT cells and Tregs, suggesting cell–cell contact is required for suppressive activity. Blocking antibodies against PD-L1, LAG-3, GITR, CCR4, HLA-DR, or CTLA-4 did not reverse the suppressive activity. We show that human PBMC-derived Tregs and MoT cells suppress stimulated CD4⁺ PBMCs in a cell contact-dependent manner, suggesting that a Foxp3⁺ Treg population suppresses immune responses by an uncharacterized cell contact-dependent mechanism.     

Synergistic antitumor effect of chemotactic-prostate tumor-associated antigen gene-modified tumor cell vaccine and anti-CTLA-4 mAb in murine tumor model

In this study, we demonstrate that an effective immune response against prostate tumors in mouse tumor model can be elicited using a strategy that combines CTLA-4 blockade and pSLC-3P-Fc-modified tumor cell vaccine (named B16F10-SLC-3P-Fc). Treatment of B16F10-3P-bearing mice resulted in a significant reduction in tumor incidence as assessed 2 months after treatment. In vivo Ab depletion confirmed that the antitumor effect was primarily CD8⁺ T cells and CD4⁺ T lymphocytes were required for the induction of CD8⁺ CTL response in B16F10-SLC-3P-Fc + anti-CTLA-4 mAb-immunized mice. Moreover, mice that were cured of an established tumor were protected against a rechallenge with the same tumor for at least 4 months, suggesting the generation of memory responses. Adoptive transfer experiments further indicate that antitumor reactivity can be transferred to naïve mice by splenocytes. These findings demonstrate that this combinatorial treatment can elicit a potent anti-tumor immune response and suggest potential of this approach for treatment of prostate cancer.     

Analysis of T cell receptor Vβ diversity in peripheral CD4+ and CD8+ T lymphocytes in patients with autoimmune thyroid diseases

Autoimmune thyroid diseases are characterized by intrathyroidal infiltration of CD4⁺ and CD8⁺ T lymphocytes reactive to self‐thyroid antigens. Early studies analysing T cell receptor (TCR) Vα gene usage have shown oligoclonal expansion of intrathyroidal T lymphocytes but not peripheral blood T cells. However, TCR Vβ diversity of the isolated CD4⁺ and CD8⁺ T cell compartments in the peripheral blood has not been characterized fully in these patients. We performed complementarity‐determining region 3 (CDR3) spectratyping as well as flow cytometric analysis for the TCR Vβ repertoire in peripheral CD4⁺ and CD8⁺ T cells from 13 patients with Graves' disease and 17 patients with Hashimoto's thyroiditis. Polyclonal TCR Vβ repertoire was demonstrated by flow cytometry in both diseases. In contrast, CDR3 spectratyping showed significantly higher skewing of TCR Vβ in peripheral CD8⁺ T cells but not CD4⁺ T cells among patients with Hashimoto's thyroiditis compared with healthy adults. We found trends towards a more skewed CDR3 size distribution in those patients having disease longer than 5 years and requiring thyroid hormone replacement. Patients with Graves' disease exhibited no skewing both in CD4⁺ and CD8⁺ T cells. These findings indicate that clonal expansion of CD8⁺ T cells in Hashimoto's thyroiditis can be detected in peripheral blood and may support the role of CD8⁺ T cells in cell‐mediated autoimmune attacks on the thyroid gland in Hashimoto's thyroiditis.     

Increase in FOXP3+ Regulatory T Cells in GVHD Skin Biopsies Is Associated with Lower Disease Severity and Treatment Response

In animal models, CD4⁺/CD25⁺ T-regulatory cells (Tregs) have been reported to prevent/delay the onset of graft-versus-host disease (GVHD). Recently, an insufficient upregulation of Tregs was found in target organ (intestinal) biopsies from patients with GVHD. We have analyzed by immunohistochemistry the number of CD3⁺ T lymphocytes and FOXP3⁺ Tregs in skin biopsies from (1) recipients of allogeneic hematopoietic stem cell transplantation (HSCT, n = 26), (2) nontransplanted patients diagnosed with cutaneous drug reaction (n = 12), and (3) healthy donors (n = 10). Infiltrating CD3⁺ cells were significantly higher in both transplanted patients showing acute GVHD (aGVHD) and drug reaction when compared to healthy donors and patients without GVHD. Tregs number in aGVHD was higher than in patients without GVHD or healthy subjects and lower than in drug reaction. Interestingly, the number of infiltrating FOXP3⁺ Tregs was significantly higher in patients responding to GVHD treatment and with a low GVHD grade. Increase in FOXP3⁺ Tregs in GVHD skin biopsies correlates with less severe GVHD and is associated with response to GVHD treatment. Larger studies are required to confirm that evaluation of Tregs in minimally invasive skin biopsies assists the diagnosis and prognosis of GVHD patients.     

In vivo anti-inflammatory activities of novel cytokine IL-38 in Murphy Roths Large (MRL)/lpr mice

The newly named interleukin (IL)-36 subfamily member IL-38 has been shown to exert anti-inflammatory activity. However, the in vivo immunomodulatory activity of IL-38 was poorly investigated in systemic lupus erythematosus (SLE). We have investigated the expression of CD4⁺IL-17⁺ Th17, CD4⁺IFN-γ⁺ Th1 and CD3⁺CD4⁻CD8⁻ double negative (DN) T cells and the related immunopathological mechanisms in female MRL/lpr mice model of spontaneous lupus-like disease, with or without IL-38 treatment. Intravenous administration of murine recombinant IL-38 into MRL/lpr mice can ameliorate the lupus-like clinical symptoms including proteinuria, leukocyteuria and skin lesions. A remission of histopathology characteristics of skin and nephritis was also observed upon IL-38 treatment. Accordingly, IL-38 receptor was expressed on the cell surface of both CD4⁺ Th and CD19⁺ B lymphocytes. The splenic Th17 and DN T lymphocytes, the average mRNA level of epigenetically regulated gene expression of Th17 cells, and serum concentrations of IL-17 and IL-22 were significantly decreased upon the treatment of IL-38 (all p < 0.05). The in vivo results suggest that IL-38 can ameliorate skin inflammation and nephritis in SLE mice probably via suppressing the formation of inflammatory cytokines such as IL-17 and IL-22, and pathogenic DN T cells. These findings may provide a biochemical basis for further investigation of the therapeutic mechanisms of IL-38 for the treatment of autoimmune-mediated inflammation.     

A specific immune tolerance toward offspring cells is to exist after the mother lymphocyte infusion

PurposeTo examine immune tolerance between maternal lymphocytes and offspring tissue after a donor lymphocyte infusion.MethodsMouse models were established by mating female BALB/c mice with male C57BL mice. Splenic lymphocytes from donors of different genetic backgrounds were labeled with carboxyfluorescein succinimidyl ester (CFSE), and 1 × 10⁷ of the labeled cells were intravenously injected into a recipient. At 6 h, 24 h, 72 h and 120 h after the infusion, mononuclear cells in recipient spleen, liver, thymus, lymph nodes, and peripheral blood were collected. CFSE+, CFSE-, CD3+, CD8+, CD4+, CD19+, NK1.1+, CD25+, and CD127+ lymphocytes in those samples were analyzed by flow cytometry. The distribution of donor T cells, B cells, NK cells, helper T cells, cytotoxic T cells, and recipient regulatory T cells in the tissues were then analyzed.ResultsMaternal lymphocytes were more likely to survive in offspring. At 120 h after infusion, the percentages of maternal cells in the offspring were 0.52 ± 0.11% in lymph nodes, 0.97 ± 0.04% in peripheral blood, and 0.97 ± 0.11% in the spleen. Few donor cells, if any, were detected in these tissues at 120 h after aunt to child, father to child, and unrelated allogeneic infusions were performed. The subtype proportion of donor lymphocytes changed significantly in the recipient tissues. Recipient Treg cells increased in the mother to child group, but not in the aunt to child, father to child, and unrelated allogeneic groups, suggesting a decreased cellular immune response to allogeneic cells in the mother to child group. At 120 h after the infusion, no donor cells were detected in the recipient livers and thymuses of all groups, implying that donor cells were barely able to colonize in the liver and thymus.ConclusionSpecific immune tolerance to maternal lymphocytes exists in offspring. An infusion of maternal donor lymphocytes may produce a relatively persistent effect of adoptive immunotherapy with reduced side-effects.     

Characterization of CD4/CD8+ αβ and Vγ2Vδ2+ T cells in HIV-negative individuals with different Mycobacterium tuberculosis infection statuses

BackgroundThe immune responses of T cell subsets among patients with different Mycobacterium tuberculosis (M.tb) infection statuses [i.e., active tuberculosis (ATB), latent tuberculosis infection (LTBI) and non-infection (healthy control, HC)] have not been fully elucidated in HIV-negative individuals. Specifically, data are limiting in high tuberculosis epidemic regions in China. To investigate the distributions and functions of T cell subsets (i.e., CD3+, CD4+, CD8+ αβ and Vγ2Vδ2+ T cells) in HIV-negative subjects with different M.tb infection statuses, we conducted a case-control study that enrolled 125 participants, including ATB patients (n = 46), LTBI subjects (n = 34), and HC (n = 45).ResultsAn IFN-γ release assay (IGRA) was employed to screen LTBI subjects. Whole blood cell surface staining and flow cytometry were used to detect phenotypic distributions of T cells in the peripheral blood mononuclear cells (PBMCs) and tuberculous pleural fluid mononuclear cells (PFMCs). PPD and the phosphorylated antigen HMBPP were employed as stimulators for the detection of M.tb antigen-specific T cell functions via intracellular cytokine staining (ICS). The absolute numbers of T cell subsets, including CD3+ CD4+, CD3+ CD8+ αβ and Vγ2Vδ2+ T cells, were significantly reduced in active tuberculosis compared with latent tuberculosis or the healthy controls. Importantly, PPD-specific CD3+ CD4+ and CD3+ CD8+ αβ T cells and HMBPP-specific Vγ2Vδ2+ T cells in ATB patients were also significantly reduced compared to the LTBI/HC subjects (P < 0.05). In contrast, the proportion of CD4+ T cells in PFMCs was higher compared to PBMCs, while CD8+ and Vγ2Vδ2+ T cells in PFMCs were lower compared to PBMCs (all P < 0.05). PPD-specific CD4+ T cells predominated among CD3+ T cells in PFMCs.ConclusionsCellular immune responses are impaired in ATB patients. Antigen-specific CD4+ T cell may migrate from the periphery to the lesion site, where they exert anti-tuberculosis functions.     

High-throughput sequencing reveals restricted TCR Vβ usage and public TCRβ clonotypes among pancreatic lymph node memory CD4+ T cells and their involvement in autoimmune diabetes

Islet-reactive memory CD4⁺ T cells are an essential feature of type 1 diabetes (T1D) as they are involved in both spontaneous disease and in its recurrence after islet transplantation. Expansion and enrichment of memory T cells have also been shown in the peripheral blood of diabetic patients. Here, using high-throughput sequencing, we investigated the clonal diversity of the TCRβ repertoire of memory CD4⁺ T cells in the pancreatic lymph nodes (PaLN) of non-obese diabetic (NOD) mice and examined their clonal overlap with islet-infiltrating memory CD4 T cells. Both prediabetic and diabetic NOD mice exhibited a restricted TCRβ repertoire dominated by clones expressing TRBV13-2, TRBV13-1 or TRBV5 gene segments. There is a limited degree of TCRβ overlap between the memory CD4 repertoire of PaLN and pancreas as well as between the prediabetic and diabetic group. However, public TCRβ clonotypes were identified across several individual animals, some of them with sequences similar to the TCRs from the islet-reactive T cells suggesting their antigen-driven expansion. Moreover, the majority of the public clonotypes expressed TRBV13-2 (Vβ8.2) gene segment. Nasal vaccination with an immunodominat peptide derived from the TCR Vβ8.2 chain led to protection from diabetes, suggesting a critical role for Vβ8.2⁺ CD4⁺ memory T cells in T1D. These results suggest that memory CD4⁺ T cells bearing limited dominant TRBV genes contribute to the autoimmune diabetes and can be potentially targeted for intervention in diabetes. Furthermore, our results have important implications for the identification of public T cell clonotypes as potential novel targets for immune manipulation in human T1D.     

The stimulation of CD8+ T cells by dendritic cells pulsed with polyketal microparticles containing ion-paired protein antigen and poly(inosinic acid)–poly(cytidylic acid)

New adjuvants and delivery strategies are needed to optimize the ability of protein-based vaccines to elicit CD8⁺ T cell responses. We have developed a model vaccine formulation containing ovalbumin (OVA) and the double-stranded RNA analog poly(inosinic acid)–poly(cytidylic acid) (poly(I:C)), a TLR3 agonist. OVA and poly(I:C) were each ion-paired to cetyltrimethylammonium bromide (CTAB) to produce hydrophobic complexes, which were co-encapsulated in pH-sensitive polyketal (PK3) microparticles (1–3 μm) using a single emulsion method. Loading levels ranged from 13.6 to 18.8 μg/mg OVA and 4.8 to 10.3 μg/mg poly(I:C). Murine splenic dendritic cells (DCs) pulsed with PK3-OVA–poly(I:C) microparticles, at antigen doses of 0.01 and 0.1 μg/mL, induced a higher percentage of IFNγ-producing CD8⁺ T cells than DCs treated with PK3-OVA particles or soluble OVA/poly(I:C). A higher antigen dose (1 μg/mL) was less effective, which can be attributed to CTAB toxicity. At the lowest antigen dose (0.01 μg/mL), PK3-OVA–poly(I:C) microparticles also enhanced TNF-α and IL-2 production in CD8⁺ T cells. These data demonstrate the potential of polyketal microparticles in formulating effective CD8⁺ T cell-inducing vaccines comprising protein antigens and dsRNA adjuvants.     

Th17 and regulatory T lymphocytes in primary biliary cirrhosis and systemic sclerosis as models of autoimmune fibrotic diseases

Fibrotic autoimmune diseases are characterized by an inflammatory process in which fibrogenic cytokines, such as TGFβ and IL6, have a major role. Interestingly, these cytokines are also involved in the generation and function of both an effector T lymphocyte subpopulation, the Th17 cells, and the regulatory T lymphocytes (Treg). These evidences raised the hypothesis that an unbalanced equilibrium induced by the overproduction of the fibrogenic cytokines may have pathogenic relevance in fibrotic autoimmune diseases.On this basis, this review analyzes the available data concerning Th17 and Treg generation and function in two representative fibrotic autoimmune diseases, primary biliary cirrhosis (PBC) and systemic sclerosis (SSc), as models for organ-specific and systemic diseases, respectively.With regard to the Th17 cells, their expansion was found to be a common feature associated with a relative contraction of Th1 immune responses. Concerning to the regulatory T cell compartment, quantitative and qualitative alterations were observed in both diseases. However, while PBC patients showed defects only in the CD8 + Treg subset, SSc patients demonstrated abnormalities regarding to both the CD4 + CD25 + and the CD8 + Treg subpopulations. Hence, the CD8 + Treg subset seems to be the most involved in the pathogenic cascade leading to fibrotic disease onset and maintenance.Collectively, the reviewed data support the concept that altered homeostasis between effector and regulatory T cell circuits is present in fibrotic autoimmune diseases and that the major factors responsible for such disequilibrium are Th17 cells in the effector arm and CD8 + Treg in the regulatory arm.     

The tyrosine kinase inhibitor tyrphostin AG126 reduces activation of inflammatory cells and increases Foxp3+ regulatory T cells during pathogenesis of rheumatoid arthritis

Protein tyrosine kinases are key mediators of the signal transduction cascades that control expression of many genes involved in the induction of inflammation caused by arthritis. Here we investigate the effect of the tyrosine kinase inhibitor tyrphostin AG126 on a mouse model of adjuvant-induced arthritis (AIA). We report that when given at 5 mg/kg i.p. every 48 h from days 0–21, AG126 exerts potent anti-arthritic effects. Further, we investigated the role of AG126 on the key mediators of arthritic inflammation, namely, edema, arthritic score, presence of immunophenotypes including Foxp3⁺, CD4⁺Foxp3⁺, and CD25⁺Foxp3⁺ T regulatory (Treg) cells, as well as pro- and anti-inflammatory mediators. AG126 treatment significantly attenuated the severity of AIA and caused a substantial reduction in the percentage of CD2⁺, CD3⁺, CD4⁺, CD8⁺, CD23⁺, CD80⁺, CD86⁺ CD122⁺, CD195⁺, TCRβ⁺, and GITR⁺ cells in whole blood. Moreover, administration of AG126 under arthritis-inducing conditions resulted in suppression of IL-17A⁺, IFN-γ⁺, CD4⁺ and CD25⁺ populations while causing an increase in the Foxp3⁺, CD4⁺Foxp3⁺, and CD25⁺Foxp3⁺ Treg populations in the spleen. In addition, RT-PCR analysis revealed increased expression of CD4, CD8, IL-17A, IFN-γ, TNF-α, and NF-κB p65 mRNAs and decreased IL-4 mRNA in the arthritic control (AC) mice, while treatment of animals with AG126 reversed these effects. Western blot analysis confirmed the decreased expression of IL-17, GITR, NF-κB p65 proteins and increased Foxp3 and IL-4 proteins following AG126 treatment of knee tissue. Thus, our findings provide new evidence that inhibition of protein tyrosine kinase activity decreases the progression of arthritis.     

Immune system development during early childhood in tropical Latin America: evidence for the age-dependent down regulation of the innate immune response

The immune response that develops in early childhood underlies the development of inflammatory diseases such as asthma and there are few data from tropical Latin America (LA). This study investigated the effects of age on the development of immunity during the first 5 years of life by comparing innate and adaptive immune responses in Ecuadorian children aged 6–9 months, 22–26 months, and 48–60 months. Percentages of naïve CD4+ T cells declined with age while those of memory CD4⁺ and CD8⁺ T cells increased indicating active development of the immune system throughout the first five years. Young infants had greater innate immune responses to TLR agonists compared to older children while regulatory responses including SEB-induced IL-10 and percentages of FoxP3⁺ T-regulatory cells decreased with age. Enhanced innate immunity in early life may be important for host defense against pathogens but may increase the risk of immunopathology.