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Variants in STAT4 are associated with systemic lupus erythematosus (SLE) and other autoimmune diseases. How disease-associated variants affect STAT4 expression, in particular in CD4 T cells where STAT4 plays an essential role, is unknown.We compared Th1 differentiation between naïve CD4 T cells from healthy donors (HD) homozygous for the risk (R/R) or non-risk (NR/NR) alleles. We analyzed epigenetic marks in STAT4 and evaluated the relevance of its third intron. We assessed the consequences of Stat4 overexpression in vivo. We analyzed the effects of the STAT4 genotype in patients with lupus nephritis.Naïve CD4 T cells from NR/NR HD, downregulated STAT4 in response to IL-12. In contrast, cells from R/R HD maintained high levels. R/R cells exhibited higher abundance of transcriptionally active STAT4 and increased IFN-γ production. Accordingly, R/R HD exhibited a stronger induction of local active enhancer marks. Genetic editing confirmed the presence of a negative regulatory region in the STAT4 third intron, where most of the SLE-associated STAT4 SNPs are located. In vivo forced expression demonstrated that increases in Stat4 levels in T cells enhanced glomerulonephritis. Accordingly, the R/R genotype was associated with suboptimal response to treatment and with worse clinical outcomes in patients with proliferative lupus nephritis.The SLE-associated STAT4 haplotype is associated with abnormal IL-12-mediated STAT4 transcriptional regulation. Carriers of the risk variant exhibit exaggerated CD4 pro-inflammatory capacities that, in the context of SLE, contribute to a more severe disease. R/R patients may benefit from blockade of the IL-12-STAT4 pathway. This article is protected by copyright. All rights reserved.

Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, the causative agent of coronavirus disease 2019 (COVID-19), may lead to severe systemic inflammatory response, pulmonary damage, and even acute respiratory distress syndrome (ARDS). This in turn may result in respiratory failure and in death. Experimentally, acetylcholine (ACh) modulates the acute inflammatory response, a neuro-immune mechanism known as the inflammatory reflex. Recent clinical evidence suggest that electrical and chemical stimulation of the inflammatory reflex may reduce the burden of inflammation in chronic inflammatory diseases. Pyridostigmine (PDG), an ACh-esterase inhibitor (i-ACh-e), increases the half-life of endogenous ACh, therefore mimicking the inflammatory reflex. This clinical trial is aimed at evaluating if add-on of PDG leads to a decrease of invasive mechanical ventilation and death among patients with severe COVID-19. Methods A parallel-group, multicenter, randomized, double-blinded, placebo-controlled, phase 2/3 clinical trial to test the efficacy of pyridostigmine bromide 60 mg/day P.O. to reduce the need for invasive mechanical ventilation and mortality in hospitalized patients with severe COVID-19. Discussion This study will provide preliminary evidence of whether or not -by decreasing systemic inflammation- add-on PDG can improve clinical outcomes in patients with severe COVID-19. Trial registration ClinicalTrials.gov NCT04343963 (registered on April 14, 2020).

The cellular origin of CD4− CD8− (double negative, DNT) TCR-α/β+ T cells remains unknown. Available evidence indicates that they may derive from CD8+ T cells, but most published data have been obtained using cells that bear an invariant transgenic T cell receptor that recognizes an Ag that is not present in normal mice. Here, we have used complementary fate mapping and adoptive transfer experiments to identify the cellular lineage of origin of DNT cells in wild-type mice with a polyclonal T cell repertoire. We show that TCR-α/β+ DNT cells can be traced back to CD8+ and CD4+CD8+ double positive cells in the thymus. We also demonstrate that polyclonal DNT cells generated in secondary lymphoid organs proliferate upon adoptive transfer and can regain CD8 expression in lymphopenic environment. These results demonstrate the cellular origin of DNT cells and provide a conceptual framework to understand their presence in pathological circumstances.

Adaptive immune responses rely on the proliferation of T lymphocytes able to recognize and eliminate pathogens. The magnitude and duration of the expansion of activated T cell clones are finely regulated to minimize immunopathology and avoid autoimmunity. In patients with rheumatic autoimmune diseases, such as systemic lupus erythematosus and rheumatoid arthritis, activated lymphocytes survive and exert effector functions for prolonged periods, defying the mechanisms that normally curb their capacities during acute and chronic infections. Here, we review the molecular mechanisms that limit the duration of immune responses in health and discuss the factors that alter such regulation in the setting of systemic lupus erythematosus and rheumatoid arthritis. We highlight defects that could contribute to the development and progression of autoimmune disease and describe how chronic inflammation can alter the regulation of activated lymphocyte survival, promoting its perpetuation. These concepts might contribute to the understanding of the mechanisms that underlie the chronicity of inflammation in the context of autoimmunity.

Systemic autoimmune diseases are complex clinical conditions that arise in genetically predisposed individuals as a result of the interplay between their immune system and their environment. In this perspective, we briefly discuss our current understanding of the pathogenesis of autoimmunity and indicate four research avenues whose exploration will bring us closer to resolving fundamental questions that remain unanswered in this enigmatic field.

COVID-19 can range from asymptomatic to life-threatening. Early identification of patients who will develop severe disease is crucial. A number of scores and indexes have been developed to predict severity. However, most rely on measurements not readily available. We evaluated hematological and biochemical markers taken on admission and determined how predictive they were of development of critical illness or death. We observed that higher values of readily available tests, including neutrophil:lymphocyte ratio; derived neutrophil index; and troponin I were associated with a higher risk of death or critical care admission (P

Background: Regulatory CD4+ T cells (Tregs) exhibit functional alterations in patients with multiple sclerosis (MS). Transforming growth factor (TGF)-β is a key regulator of Treg development and function. Objective: The objective of this study is to determine whether the expression of functionally relevant TGF-β-regulated molecules is altered in Tregs from patients with MS. Methods: Expression of nine Treg markers was analyzed by multi-color flow cytometry in CD4+ T cells and Treg subpopulations of 31 untreated MS patients and age- and sex-matched healthy donors (HDs). Correlations between Treg marker expression and clinical variables were sought. Results: Expression of the transcription factor Helios, which defines thymic-derived Tregs, was decreased in this Treg subpopulation. The frequency of peripherally generated Tregs was increased in patients with MS, particularly in patients with progressive MS. Low frequencies of thymic-derived Tregs were associated with magnetic resonance imaging (MRI) lesion-burden and a high relapse rate. Four surface markers associated with TGF-β signaling (ABCA1, BTLA, DNAM-1, and GARP) were differentially expressed on Tregs from patients with MS and HDs. Expression levels of CD73, CD103, ABCA1, and PAR2 showed strong correlations with disease severity. Conclusion: We have identified novel markers abnormally expressed on Tregs from patients with MS that could detect patients with severe disease.

Activation of self-reactive CD8+ T cells induces a peripheral tolerance mechanism that involves loss of CD8 expression. Because genetic deficiency of Fas and Fasl causes the accumulation of double-negative (DN; CD3+ TCR-αβ+ CD4- CD8-) T cells that have been proposed to derive from CD8+ cells, we decided to explore the role of Fas and FasL in self-antigen-induced CD8 downregulation. To this end, we quantified Fas and FasL induction by different stimuli and analyzed the effects of Fas/FasL deficiency during a protective immune response and after exposure to self-antigens. Our data describes how Fas and FasL upregulation differs depending on the setting of CD8 T cell activation and demonstrates that Fas/FasL signaling maintains CD8 expression during repetitive antigen stimulation and following self-antigen encounter. Together, our results reveal an unexpected role of Fas/FasL signaling and offer a new insight into the role of these molecules in the regulation of immune tolerance.

OBJECTIVES: Genistein promotes fatty acid oxidation, improves glucose tolerance and increases energy expenditure. These effects are associated with AMPK phosphorylation in skeletal muscle. However, the molecular mechanism by which genistein activates the signaling pathway to activate AMPK phosphorylation is not yet known. Several target proteins have been suggested, one o them is GPR30, but it has not been studied. Thus, the aim of this study was to determine if AMPK phosphorylation by genistein is activated by GPR30. METHODS: To determine if GPR30 is involved in the mechanism that promotes AMPK phosphorylation we used C2C12 GPR30 KD (knock down) myotubes obtained by transduction with a shRNA, and also GPR30 −/− primary myotubes. AMPK phosphorylation was determined via western blot in the presence of genistein after 1 hour in both cultures. Furthermore, in order to establish in vivo if the beneficial effects of genistein were associated to GPR30, C57BL/6 mice (wild type WT) and GPR30 −/− mice were fed with both control and high fat sucrose diets (HFSD) containing genistein for 2 months. During two months of treatment, weight gain, food consumption, and body composition were measured as well as a glucose tolerance test (GTT), indirect calorimetry and AMPK phosphorylation by western blot in skeletal muscle of all of groups. RESULTS: Genistein at concentrations of 0.3,1,3 and 10µM increased AMPK phosphorylation in GPR30 KD, and GPR30 −/− primary myotubes, indicating that GPR30 is not directly involved in AMPK phosphorylation by genistein in an in vitro model. The in vivo study showed that the effect of genistein in GPR30 −/− mice on weight gain, body composition, GTT and indirect calorimetry was similar compared to wild type mice. The mice that consumed a HFSD with genistein gained less weight and less body fat, regardless of genotype (WT or GPR30 −/−). Similar effects were observed in the glucose tolerance test, oxygen exchange coefficient and oxygen consumption. Wild type and GPR30 −/− mice that consumed genistein had a better glucose tolerance than those that did not consume genistein. CONCLUSIONS: This study showed that GPR30 its not directly involved in promoting AMPK phosphorylation by genistein. In addition, genistein reduced weight gain, increased glucose tolerance and increased oxygen consumption even in the absence of GPR30. FUNDING SOURCES: INCMNSZ.

Protein phosphatase 2A (PP2A), a serine/threonine phosphatase, has been shown to control T cell function. We found that in vitro–activated B cells and B cells from various lupus-prone mice and patients with systemic lupus erythematosus display increased PP2A activity. To understand the contribution of PP2A to B cell function, we generated a Cd19(Cre)Ppp2r1a(fl/fl) (flox/flox) mouse which lacks functional PP2A only in B cells. Flox/flox mice displayed reduced spontaneous germinal center formation and decreased responses to T cell-dependent and T-independent antigens, while their B cells responded poorly in vitro to stimulation with an anti-CD40 antibody or CpG in the presence of IL-4. Transcriptome and metabolome studies revealed altered nicotinamide adenine dinucleotide (NAD) and purine/pyrimidine metabolism and increased expression of purine nucleoside phosphorylase in PP2A-deficient B cells. Our results demonstrate that PP2A is required for optimal B cell function and may contribute to increased B cell activity in systemic autoimmunity.

Chronic inflammation causes target organ damage in patients with systemic autoimmune diseases. The factors that allow this protracted response are poorly understood. We analyzed the transcriptional regulation of PPP2R2B (B55β), a molecule necessary for the termination of the immune response, in patients with autoimmune diseases. Altered expression of B55β conditioned resistance to cytokine withdrawal–induced death (CWID) in patients with autoimmune diseases. The impaired upregulation of B55β was caused by inflammation-driven hypermethylation of specific cytosines located within a regulatory element of PPP2R2B preventing CCCTC-binding factor binding. This phenotype could be induced in healthy T cells by exposure to TNF-α. Our results reveal a gene whose expression is affected by an acquired defect, through an epigenetic mechanism, in the setting of systemic autoimmunity. Because failure to remove activated T cells through CWID could contribute to autoimmune pathology, this mechanism illustrates a vicious cycle through which autoimmune inflammation contributes to its own perpetuation.

How T cells integrate environmental cues into signals that limit the magnitude and length of immune responses is poorly understood. Here, we provide data that demonstrate that B55β, a regulatory subunit of protein phosphatase 2A, represents a molecular link between cytokine concentration and apoptosis in activated CD8(+) T cells. Through the modulation of AKT, B55β induced the expression of the proapoptotic molecule Hrk in response to cytokine withdrawal. Accordingly, B55β and Hrk were both required for in vivo and in vitro contraction of activated CD8(+) lymphocytes. We show that this process plays a role during clonal contraction, establishment of immune memory, and preservation of peripheral tolerance. This regulatory pathway may represent an unexplored opportunity to end unwanted immune responses or to promote immune memory.

CD8 T cells can kill malignant cells in an antigen-specific manner. However, anti-tumoral responses are usually limited by suppressive factors that curb the effector responses of tumor-infiltrating CD8 T cells. Therapeutic strategies to overcome intra-tumoral T cell suppression, for example immune checkpoint inhibition, have been clinically effective in patients with cancer. Here, we provide data that demonstrates that GK-1, a peptide derived from the parasite Taenia crassiceps, promotes an anti-melanoma CD8 T cell response with heightened effector characteristics that leads to an increased amount of tumor-infiltrating CD44+ IFN-γ-producing CD8 T cells. The response induced by GK-1 was associated with a reduction in the expression of PD-1 and PD-L1 on tumor-infiltrating CD8 and dendritic cells, respectively, effects that led to a dramatic decrease in tumor burden. Our results suggest that the immunomodulatory properties of GK-1 may promote a CD8 T cell response that may be therapeutically useful in the setting of cancer.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease linked to profound defects in the function and phenotype of T lymphocytes. Here, we describe abnormal signaling pathways that have been documented in T cells from patients with SLE and discuss how they impact gene expression and immune function, in order to understand how they contribute to disease development and progression.

TCR-αβ(+) double negative (DN) T cells (CD3(+) TCR-αβ(+) CD4(-) CD8(-) NK1.1(-) CD49b(-) ) represent a minor heterogeneous population in healthy humans and mice. These cells have been ascribed pro-inflammatory and regulatory capacities and are known to expand during the course of several autoimmune diseases. Importantly, previous studies have shown that self-reactive CD8(+) T cells become DN after activation by self-antigens, suggesting that self-reactive T cells may exist within the DN T-cell population. Here, we demonstrate that programmed cell death 1 (PD-1) expression in unmanipulated mice identifies a subset of DN T cells with expression of activation-associated markers and a phenotype that strongly suggests they are derived from self-reactive CD8(+) cells. We also found that, within DN T cells, the PD-1(+) subset generates the majority of pro-inflammatory cytokines. Finally, using a TCR-activation reporter mouse (Nur77-GFP), we confirmed that in the steady-state PD-1(+) DN T cells engage endogenous antigens in healthy mice. In conclusion, we provide evidence that indicates that the PD-1(+) fraction of DN T cells represents self-reactive cells.

Purpose of review The aim of this review is to discuss recent developments in our understanding of how systemic lupus erythematosus (SLE)-associated genes contribute to autoimmunity. Recent findings Gene-function studies have revealed mechanisms through which SLE-associated alleles of IFIH1, TNFAIP3, IRF5, and PRDM1 likely contribute to the development of autoimmunity. Novel research has identified Mac-1 (encoded by ITGAM), CaMK4, and iRhom2 as plausible therapeutic targets in lupus nephritis. Summary The work discussed in this review has broad implications for our understanding of the pathogenesis of SLE and for the development of novel therapeutic strategies.

TCR-αβ+ double-negative (DN; CD4−CD8−) T cells represent a poorly understood cellular subset suggested to contribute to the pathogenesis of the autoimmune disease systemic lupus erythematosus. DN T cells have been proposed to derive from CD8+ cells. However, the conditions that govern the loss of CD8 expression after Ag encounter are unknown. In this study, we tracked the fate of CD8 T cells from transgenic TCR mice exposed to their cognate Ags as self or in the context of infection. We demonstrate that CD8 T cells lose CD8 expression and become DN only when cognate Ag is sensed as self. This process is restricted to tissues where the Ag is present. We also show that DN T cells derived from self-reactive CD8 cells express the inhibitory molecules PD-1 and Helios. These molecules identify a subset of DN T cells in normal mice. A similar population expands when CD8 T cells from repertoires enriched in self-reactive cells (Aire-deficient) are transferred into cognate hosts. Collectively, our data suggest that a subset of DN T cells, identified by the expression of PD-1 and Helios, represent self-reactive cells. Our results provide an explanation for the origin of DN T cells and introduce CD8 loss as a process associated with self-Ag encounter.

Disease heterogeneity remains a major challenge for the understanding of systemic lupus erythematosus (SLE). Recent work has revealed the important role of nonimmune factors in the development of end-organ damage involvement, shifting the current paradigm that views SLE as a disease inflicted by a disturbed immune system on passive target organs. Here, we discuss the pathogenesis of lupus nephritis in a comprehensive manner, by incorporating the role that target organs play by withstanding and modulating the local inflammatory response. Moreover, we consider the effects that genetic variants exert on immune and nonimmune cells in order to shape the phenotype of the disease in each affected individual.

Binding of programmed death-1 (PD-1) with its ligands (PD-L1/2) transmits a co-inhibitory signal in activated T-cells that promotes T-cell exhaustion, leading to tumor immune evasion. The efficacy of antibodies targeting PD-1 and PD-L1 has led to a paradigm shift in lung cancer treatment but the prognostic and predictive value of tumor PD-L1 expression remains controversial. Evaluating PD-1, PD-L1/2 expression in peripheral blood cells may serve as a potential biomarker for prognosis and response to therapy. In this prospective observational study, plasma cytokine levels and PD-1, PD-L1 and PD-L2 expression was evaluated in circulating CD3+, CD3+CD4+ and CD3+CD8+ cells from 70 treatment-naive patients with advanced NSCLC (Stage IIIB and IV) and from 10 healthy donors. The primary objective was to assess OS according to PD-1, PD-L1, PD-L2 expression status on PBMCs and lymphocyte subsets. Our results indicate that the percentage of PD-L1+CD3+, PD-L1+CD3+CD8+ PD-L2+PBMCs, PD-L2+CD3+, PD-L2+CD3+CD4+ cells was higher in patients than in healthy donors. Survival was decreased among patients with a high percentage of either PD-1+PBMCs, PD-1+CD3+, PD-L1+CD3+, PD-L1+CD3+CD8+, PD-L2+CD3+, PD-L2+CD3+CD4+, or PD-L2+CD3+CD8+ cells. IL-2 and TNF-α showed the strongest association with PD-L1 and PD-L2 expression on specific subsets of T-lymphocytes. Our findings suggest that increased PD-1/PD-L1/PDL-2 expression in PBMCs, particularly in T-cells, may be an additional mechanism leading to tumor escape from immune control. This study is registered with ClinicalTrials.gov, number NCT02758314.

The immune-regulatory cytokine IL-10 plays a central role during innate and adaptive immune responses. IL-10 is elevated in the serum and tissues of patients with systemic lupus erythematosus (SLE), an autoimmune disorder characterized by autoantibody production, immune-complex formation, and altered cytokine expression. Because of its B cell-promoting effects, IL-10 may contribute to autoantibody production and tissue damage in SLE. We aimed to determine molecular events governing T cell-derived IL-10 expression in health and disease. We link reduced DNA methylation of the IL10 gene with increased recruitment of Stat family transcription factors. Stat3 and Stat5 recruitment to the IL10 promoter and an intronic enhancer regulate gene expression. Both Stat3 and Stat5 mediate trans-activation and epigenetic remodeling of IL10 through their interaction with the histone acetyltransferase p300. In T cells from SLE patients, activation of Stat3 is increased, resulting in enhanced recruitment to regulatory regions and competitive replacement of Stat5, subsequently promoting IL-10 expression. A complete understanding of the molecular events governing cytokine expression will provide new treatment options in autoimmune disorders, including SLE. The observation that altered activation of Stat3 influences IL-10 expression in T cells from SLE patients offers molecular targets in the search for novel target-directed treatment options.

TCR-αβ(+)CD3(+)CD4(-)CD8(-) "double negative" T cells are expanded in the peripheral blood of patients with systemic lupus erythematosus (SLE) and lupus-prone mice. Double negative T cells have been claimed to derive from CD8(+) cells that down-regulate CD8 co-receptors and acquire a distinct effector phenotype that includes the expression of proinflammatory cytokines. This, along with the fact that double negative T cells have been documented in inflamed organs, suggests that they may contribute to disease expression and tissue damage. We recently linked the transcription factor cAMP responsive element modulator (CREM) α, which is expressed at increased levels in T cells from SLE patients and lupus prone MRL/lpr mice, with trans-repression of a region syntenic to the murine CD8b promoter. However, the exact molecular mechanisms that result in a stable silencing of both CD8A and CD8B genes remain elusive. Here, we demonstrate that CREMα orchestrates epigenetic remodeling of the CD8 cluster through the recruitment of DNA methyltransferase (DNMT) 3a and histone methyltransferase G9a. Thus, we propose that CREMα is essential for the expansion of double negative T cells in SLE. CREMα blockade may have therapeutic value in autoimmune disorders with DN T cell expansion.

Cytotoxic T Lymphocyte Antigen-4 (CTLA-4) is a costimulatory receptor in the immunoglobulin superfamily closely related to CD28 and ICOS, and binds to CD80 and CD86 (1;2). Expression of CTLA-4 is constitutive on regulatory T cells (3) and induced following activation on effector T cells (1). It exerts an essential inhibitory role and its absence causes an early and lethal autoimmune disease in mice (4). The CTLA4 gene is highly conserved (76% homology between human and mouse) (5). It is comprised of 4 exons: exon 1 codes for the signal peptide; exon 2 for the ligand-binding domain; exon 3 for the transmembrane region; exon 4 for the intra-cytoplasmic tail (Figure 1A) (6). Human peripheral blood lymphocytes express 3 isoforms of CTLA-4 produced by alternative splicing: full length CTLA-4 (flCTLA-4; all four exons), soluble CTLA-4 (exons 1, 2, and 4), and a short variant that lacks both the ligand-binding domain and the transmembrane domain (1/4 CTLA-4) (6). Allelic variations and single nucleotide polymorphisms in the CTLA4 gene have been associated to several human autoimmune diseases including autoimmune thyroid disease (6), rheumatoid arthritis (7) and systemic lupus erythematosus (SLE) (8;9). Interestingly, the polymorphisms associated with autoimmune disease affect CTLA4 splicing and thus the relative expression of each variant isoform (6). How the differential expression of CTLA-4 isoforms impacts susceptibility to autoimmune disease is not yet clear. Figure 1 The 1/4 CTLA-4 splice variant codes for a secreted protein The 1/4 CTLA-4 isoform lacks the CD80/86-binding domain and the transmembrane portion and thus its function remains unclear. Forced expression of the 1/4 CTLA-4 isoform in T cells was shown to induce spontaneous autoimmune disease and facilitate the development of experimental allergic encephalomyelitis in C57BL/6 mice through an unknown mechanism (10). Here we demonstrate that in lupus-prone mice increased expression of 1/4 CTLA-4 accelerates autoimmunity, exacerbates disease pathology, and causes early mortality.

Human neurocysticercosis (NC) is caused by Taenia solium larvae lodged in the central nervous system. Most cases occur with no, or mild, neurological symptoms. However, in some patients, neuroinflammation is exacerbated, leading to severe forms of the disease. Considering the critical role of regulatory T cells (Tregs) in balancing inflammation in chronic diseases, their participation in restraining the inflammatory response in NC was explored in the present study. The frequency of Tregs and their relationship with the level of the proliferative response, the level of activated lymphocytes, and the cytokines expressed were determined in severe NC patients compared with those from healthy donors. Significantly increased peripheral Tregs (CD4(+)CD25(high) and CD4(+)CD25(high)FoxP3(+), CD4(+)CD25(high)CTLA4(+), and CD4(+)CD25(high) IL10(+)) and a significant decrease in activated (CD38(+) and CD69(+)) T cells were observed in 19 NC patients versus 10 healthy subjects. Significantly increased Tregs in NC are accompanied by a depressed specific, and non-specific, lymphocyte proliferative response, and they negatively correlate with activated CD4(+)CD69(+) lymphocytes. Treg frequencies were also determined in cerebral spinal fluid for 8 of the 19 NC patients. A positive significant correlation between peripheral and local Tregs was observed. Here, we report for the first time data that support the possible contribution of local and systemic Tregs in limiting neuroinflammation in NC.

The aim of this study was to determine whether the abundance of regulatory T cells (Tregs) (CD4+CD25high) affects thede novodevelopment of anti-HLA donor-specific antibodies (DSAs) in kidney transplant recipients (KTRs).Methods. Unsensitized (PRA ≤ 10%, no DSA) adult primary KTRs who received a living (83%) or deceased (17%) KT in our Institution during 2004/2005 were included. DSA testing was performed monthly, and Tregs were quantified by flow cytometry every 3 months, during the 1st year after KT. All patients received triple drug immunosuppressive therapy (CNI + MMF or AZA + PDN); 83% received anti-CD25.Results. 53 KTRs were included; 32% developed DSA during the 1st year after KT. Significantly lower 7-year graft survival was observed in those who developed DSA. No difference was observed in Treg numbers up to 9 months after KT, between DSA positive and negative. However, at 12 months after KT, DSA-negative patients had significantly higher numbers of Treg.Conclusions. Early development of DSA was not associated to variations in Treg abundance. The differences in Treg numbers observed at the late time point may reflect better immune acceptance of the graft and may be associated to long-term effects. Additional inhibitory mechanisms participating earlier in DSA development after KT deserve to be sought.

Systemic lupus erythematosus (SLE) is an autoimmune disease associated with chronic immune activation and tissue damage. Organ damage in SLE results from the deposition of immune complexes and the infiltration of activated T cells into susceptible organs. Cytokines are intimately involved in every step of the SLE pathogenesis. Defective immune regulation and uncontrolled lymphocyte activation, as well as increased antigen presenting cell maturation are all influenced by cytokines. Moreover, expansion of local immune responses as well as tissue infiltration by pathogenic cells is instigated by cytokines. In this review, we describe the main cytokine abnormalities reported in SLE and discuss the mechanisms that drive their aberrant production as well as the pathogenic pathways that their presence promotes.

Objective Systemic lupus erythematosus (SLE) is a chronic inflammatory disease associated with aberrant immune cell function. Treatment involves the use of indiscriminate immunosuppression, which results in significant side effects. SLE T cells express high levels of calcium/calmodulin-dependent protein kinase type IV (CaMKIV), which translocates to the nucleus upon engagement of the T cell receptor–CD3 complex and accounts for abnormal T cell function. The purpose of this study was to determine whether inhibition of CaMKIV would improve disease pathology. Methods We treated MRL/lpr mice with KN-93, a CaMKIV inhibitor, starting at week 8 or week 12 of age and continuing through week 16 and evaluated skin lesions, proteinuria, kidney histopathology, proinflammatory cytokine production, and costimulatory molecule expression. We also determined the effect of silencing of CAMK4 on interferon-γ (IFNγ) expression by human SLE T cells. Results CaMKIV inhibition in MRL/lpr mice resulted in significant suppression of nephritis and skin disease, decreased expression of the costimulatory molecules CD86 and CD80 on B cells, and suppression of IFNγ and tumor necrosis factor α production. In human SLE T cells, silencing of CAMK4 resulted in suppression of IFNγ production. Conclusion We conclude that suppression of CaMKIV mitigates disease development in lupus-prone mice by suppressing cytokine production and costimulatory molecule expression. Specific silencing of CAMK4 in human T cells results in similar suppression of IFNγ production. Our data justify the development of small-molecule CaMKIV inhibitors for the treatment of patients with SLE.

T cells contribute to the initiation and perpetuation of autoimmunity in systemic lupus erythematosus (SLE), and seem to be directly involved in the development of related organ pathology. Defects associated with CD8(+) and T-regulatory (T(REG)) cell function manifest in parallel with the expanded CD3(+)CD4(-)CD8(-) T cell lineage. The cytokine expression pattern is uniquely characterized by decreased expression of interleukin (IL)-2 and increased production of IL-17 and related cytokines. Therapeutic approaches that limit the cognate interaction between T cells and B cells, prevent inappropriate tissue homing and restore T(REG) cell function and the normal cytokine milieu have been entertained. Biochemical characterization of SLE T cells has revealed distinct early and late signaling aberrations, and has enabled the identification of novel molecular targets that can be corrected with small molecules, and biomarkers that may foretell disease activity and predict organ damage.

Objective To quantify the expression of CD44 and variant isoforms CD44v3 and CD44v6 on T cells from patients with systemic lupus erythematosus (SLE), and to assess correlations of the level of expression of these molecules with disease manifestations. Methods Information on clinical and demographic characteristics was collected, and blood samples were obtained from 72 patients with SLE and 32 healthy control subjects matched to the patients by sex, race, and age. Expression of CD44 and variants CD44v3 and v6 on T cell subsets was determined by flow cytometry, and Pearson's correlations of their expression levels with clinical variables, SLE Disease Activity Index (SLEDAI) scores, and presence of lupus nephritis were determined. Wilcoxon's rank sum tests and conditional multivariable regression analyses were applied to identify differences in the expression of CD44 between patients with SLE and healthy controls. Results Expression of CD44 was higher on CD4+ and CD8+ T cells from SLE patients compared with controls (P ≤ 0.03). Expression of CD44v3 and CD44v6 was also higher on total T cells and CD4+ and CD8+ T cells from SLE patients compared with controls (P ≤ 0.03). Cell surface levels of CD44v3 on total T cells, CD4+ T cells, and CD8+ T cells as well as cell surface expression of CD44v6 on total T cells and CD4+ T cells were correlated with the SLEDAI score (P < 0.05). The presence of lupus nephritis was associated with the expression of CD44v6 on total T cells, CD4+ T cells, and CD4−CD8− T cells (P < 0.05). Positivity for anti–double-stranded DNA antibodies was associated with the expression levels of CD44v6 on T cells (P < 0.05). Conclusion These results indicate that expression levels of CD44v3 and CD44v6 on T cells may represent useful biomarkers of SLE activity.

Systemic lupus erythematosus (SLE) is an autoimmune disease that predominantly affects women and presents with manifestations derived from the involvement of multiple organs including the kidneys, joints, nervous system, and hematopoietic organs. Immune system aberrations, as well as heritable, hormonal, and environmental factors interplay in the expression of organ damage. Recent contributions from different fields have developed our understanding of SLE and reshaped current pathogenic models. Here, we review novel information that deals with 1) genes associated with disease expression, 2) immune cell molecular abnormalities that lead to autoimmune pathology, 3) the role of hormones and sex chromosomes in the development of disease, 4) environmental and epigenetic factors thought to contribute to the expression of SLE. Finally, we emphasize molecular defects intimately associated with the disease process of SLE that represent ideal therapeutic targets and disease biomarkers.

IL-17 is a cytokine with powerful proinflammatory activity. Production of IL-17 is abnormally increased in patients with systemic lupus erythematosus (SLE), a multiorgan chronic autoimmune disease. In patients with SLE,CD3+CD4−CD8−(double negative) T cells are an important source of IL-17. IL-17 produced by double negative and CD4 T cells participates in the pathogenesis of the disease. IL-17-producing T cells are present in the kidneys of patients with lupus nephritis. IL-17 increased production in patients with SLE can amplify the immune response by increasing target organ inflammation and damage and by augmenting the production of antibodies by B cells.

IL-2 plays a key role in setting the balance between immunity and tolerance. This cytokine has a dual role as the regulator of the two main phases of the immune response (proliferative and suppressive). Likewise, activation induced cell death and the induction and maintenance of regulatory T cells are the tolerance mechanisms regulated by IL-2, which convey the link between IL-2 abnormalities and the development of autoimmune disorders, such as systemic lupus erythematosus (SLE). Particularly, in SLE murine models and in humans, deficiency in IL-2 synthesis and activity has been proven. Diverse signaling pathways abnormalities (TCR, NF-kappaBeta, NF-AT) have been involved in the IL-2 transcriptional dysregulation displayed by T cells from SLE patients, and its functional relevance as part of the physiopathogenic scheme has been shown. Aberrant expression and activity of multiple IL-2 transcriptional factors, such as c-fos, and predominantly, CREM and CREB have been involved in this immune dysregulation. Diverse alterations in signaling kinases and phosphatases (PKA, PP2A, CAMKIV) and the modulation by epigenetic mechanisms have been related to the altered CREM/pCREB index. The synergic effect of multiple abnormalities in the transcriptional factors previously mentioned has been shown to be of functional relevance in lupus.