T Helper Cells: The Modulators of Inflammation in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic neurodegenerative disease characterized by the progressive loss of axonal myelin in several areas of the central nervous system (CNS) that is responsible for clinical symptoms such as muscle spasms, optic neuritis, and paralysis. The progress made in more than one decade of research in animal models of MS for clarifying the pathophysiology of MS disease validated the concept that MS is an autoimmune inflammatory disorder caused by the recruitment in the CNS of self-reactive lymphocytes, mainly CD4+ T cells. Indeed, high levels of T helper (Th) cells and related cytokines and chemokines have been found in CNS lesions and in cerebrospinal fluid (CSF) of MS patients, thus contributing to the breakdown of the blood-brain barrier (BBB), the activation of resident astrocytes and microglia, and finally the outcome of neuroinflammation. To date, several types of Th cells have been discovered and designated according to the secreted lineage-defining cytokines. Interestingly, Th1, Th17, Th1-like Th17, Th9, and Th22 have been associated with MS. In this review, we discuss the role and interplay of different Th cell subpopulations and their lineage-defining cytokines in modulating the inflammatory responses in MS and the approved as well as the novel therapeutic approaches targeting T lymphocytes in the treatment of the disease

A non-conserved amino acid variant regulates differential signalling between human and mouse CD28

CD28 superagonistic antibodies (CD28SAb) can preferentially activate and expand immunosuppressive regulatory T cells (Treg) in mice. However, pre-clinical trials assessing CD28SAbs for the therapy of autoimmune diseases reveal severe systemic inflammatory response syndrome in humans, thereby implying the existence of distinct signalling abilities between human and mouse CD28. Here, we show that a single amino acid variant within the C-terminal proline-rich motif of human and mouse CD28 (P212 in human vs. A210 in mouse) regulates CD28-induced NF-κB activation and pro-inflammatory cytokine gene expression. Moreover, this Y209APP212 sequence in humans is crucial for the association of CD28 with the Nck adaptor protein for actin cytoskeleton reorganisation events necessary for CD28 autonomous signalling. This study thus unveils different outcomes between human and mouse CD28 signalling to underscore the importance of species difference when transferring results from preclinical models to the bedside

CD28 Individual Signaling Up-regulates Human IL-17A Expression by Promoting the Recruitment of RelA/NF-κB and STAT3 Transcription Factors on the Proximal Promoter

CD28 is an important co-stimulatory receptor for T lymphocytes that, in humans, delivers TCR-independent signal leading to the up-regulation of pro-inflammatory cytokines. We have recently reported that CD28 autonomous signaling induces the expression of IL-17A in peripheral CD4+ T lymphocytes from healthy donors, multiple sclerosis, and type 1 diabetes patients. Due to the relevance of IL-17A in the pathophysiology of several inflammatory and autoimmune diseases, we characterized the mechanisms and signaling mediators responsible for CD28-induced IL-17A expression. Here we show that CD28-mediated up-regulation of IL-17A gene expression depends on RelA/NF-κB and IL-6-associated STAT3 transcriptions factors. In particular, we found that CD28-activated RelA/NF-κB induces the expression of IL-6 that, in a positive feedback loop, mediates the activation and nuclear translocation of tyrosine phosphorylated STAT3 (pSTAT3). pSTAT3 in turn cooperates with RelA/NF-κB by binding specific sequences within the proximal promoter of human IL-17A gene, thus inducing its expression. Finally, by using specific inhibitory drugs, we also identified class 1A phosphatidylinositol 3-kinase (PI3K) as a critical upstream regulator of CD28-mediated RelA/NF-κB and STAT3 recruitments and trans-activation of IL-17A promoter. Our findings reveal a novel mechanism by which human CD28 may amplify IL-17A expression in human T lymphocytes and provide biological bases for immunotherapeutic approaches targeting CD28-associated class 1A PI3K to dampen IL-17A-mediated inflammatory response in autoimmune/inflammatory disorders

Staphylococcal enterotoxin B (SEB) activates TCR- and CD28-mediated inflammatory signals in the absence of MHC class II molecules

The inflammatory activity of staphylococcal enterotoxin B (SEB) relies on its capacity to trigger polyclonal T‐cell activation by binding both T‐cell receptor (TCR) and costimulatory receptor CD28 on T cells and MHC class II and B7 molecules on antigen presenting cells (APC). Previous studies highlighted that SEB may bind TCR and CD28 molecules independently of MHC class II, yet the relative contribution of these interactions to the pro‐inflammatory function of SEB remained unclear. Here, we show that binding to MHC class II is dispensable for the inflammatory activity of SEB, whereas binding to TCR, CD28 and B7 molecules is pivotal, in both human primary T cells and Jurkat T cell lines. In particular, our finding is that binding of SEB to B7 molecules suffices to trigger both TCR‐ and CD28‐mediated inflammatory signalling. We also provide evidence that, by strengthening the interaction between CD28 and B7, SEB favours the recruitment of the TCR into the immunological synapse, thus inducing lethal inflammatory signallin

CD28 individual signaling up-regulates IL-22 expression and IL-22-mediated effector functions in human T lymphocytes

IL‐22 is a member of the IL‐10 cytokine family involved in host protection against extracellular pathogens, by promoting epithelial cell regeneration and barrier functions. Dysregulation of IL‐22 production has also frequently been observed in acute respiratory distress syndrome (ARDS) and several chronic inflammatory and autoimmune diseases. We have previously described that human CD28, a crucial co‐stimulatory receptor necessary for full T cell activation, is also able to act as a TCR independent signalling receptor and to induce the expression of IL‐17A and inflammatory cytokines related to Th17 cells, which together with Th22 cells represent the main cellular source of IL‐22. Here we characterized the role of CD28 autonomous signalling in regulating IL‐22 expression in human CD4+ T cells. We show that CD28 stimulation in the absence of TCR strongly up‐regulates IL‐22 gene expression and secretion. As recently observed for IL‐17A, we also found that CD28‐mediated regulation of IL‐22 transcription requires the cooperative activities of both IL‐6‐activated STAT3 and RelA/NF‐κ transcription factors. CD28‐mediated IL‐22 production also promotes the barrier functions of epithelial cells by inducing mucin and metalloproteases expression. Finally, by using specific inhibitory drugs, we also identified CD28‐associated class 1A phosphatidylinositol 3‐kinase (PI3K) as a pivotal mediator of CD28‐mediated IL‐22 expression and IL‐ 22‐dependent epithelial cell barrier functions

CD28 autonomous signaling orchestrates IL-22 expression and IL-22-regulated epithelial barrier functions in human T lymphocytes

IL-22 is a member of the IL-10 cytokine family involved in host protection against extracellular pathogens, by promoting epithelial cell regeneration and barrier functions. Dysregulation of IL-22 production has also frequently been observed in acute respiratory distress syndrome (ARDS) and several chronic inflammatory and autoimmune diseases. We have previously described that human CD28, a crucial co-stimulatory receptor necessary for full T cell activation, is also able to act as a TCR independent signaling receptor and to induce the expression of IL-17A and inflammatory cytokines related to Th17 cells, which together with Th22 cells represent the main cellular source of IL-22. Here we characterized the role of CD28 autonomous signaling in regulating IL-22 expression in human CD4+ T cells. We show that CD28 stimulation in the absence of TCR strongly up-regulates IL-22 gene expression and secretion. As recently observed for IL-17A, we also found that CD28-mediated regulation of IL-22 transcription requires the cooperative activities of both IL-6-activated STAT3 and RelA/NF-κB transcription factors. CD28-mediated IL-22 production also promotes the barrier functions of epithelial cells by inducing mucin and metalloproteases expression. Finally, by using specific inhibitory drugs, we also identified CD28-associated class 1A phosphatidylinositol 3-kinase (PI3K) as a pivotal mediator of CD28-mediated IL-22 expression and IL-22–dependent epithelial cell barrier functions

High feasibility and antileukemic efficacy of fludarabine, cytarabine, and idarubicin (FLAI) induction followed by risk-oriented consolidation: A critical review of a 10-year, single-center experience in younger, non M3 AML patients

About 105 consecutive acute myeloid leukemia (AML) patients treated with the same induction-consolidation program between 2004 and 2013 were retrospectively analyzed. Median age was 47 years. The first induction course included fludarabine (Flu) and high-dose cytarabine (Ara-C) plus idarubicin (Ida), with or without gemtuzumab-ozogamicin (GO) 3 mg/m2 (FLAI-5). Patients achieving complete remission (CR) received a second course without fludarabine but with higher dose of idarubicin. Patients not achieving CR received an intensified second course. Patients not scheduled for early allogeneic bone marrow transplantation (HSCT) where planned to receive at least two courses of consolidation therapy with Ara-C. Our double induction strategy significantly differs from described fludarabine-containing regimens, as patients achieving CR receive a second course without fludarabine, to avoid excess toxicity, and Ara-C consolidation is administrated at the reduced cumulative dose of 8 g/m2 per cycle. Toxicity is a major concern in fludarabine containing induction, including the recent Medical Research Council AML15 fludarabine, cytarabine, idaraubicin and G-CSF (FLAG-Ida) arm, and, despite higher anti-leukemic efficacy, only a minority of patients is able to complete the full planned program. In this article, we show that our therapeutic program is generally well tolerated, as most patients were able to receive subsequent therapy at full dose and in a timely manner, with a 30-day mortality of 4.8%. The omission of fludarabine in the second course did not reduce efficacy, as a CR rate of 83% was achieved and 3-year disease-free survival and overall survival (OS) were 49.6% and 50.9%, respectively. Our experience shows that FLAI-5/Ara-C + Ida double induction followed by risk-oriented consolidation therapy can result in good overall outcome with acceptable toxicity. Am. J. Hematol. 91:755\u2013762, 2016. \ua9 2016 Wiley Periodicals, Inc

CD28 between tolerance and autoimmunity: The side effects of animal models [version 1; referees: 2 approved]

Regulation of immune responses is critical for ensuring pathogen clearance and for preventing reaction against self-antigens. Failure or breakdown of immunological tolerance results in autoimmunity. CD28 is an important co-stimulatory receptor expressed on T cells that, upon specific ligand binding, delivers signals essential for full T-cell activation and for the development and homeostasis of suppressive regulatory T cells. Many in vivo mouse models have been used for understanding the role of CD28 in the maintenance of immune homeostasis, thus leading to the development of CD28 signaling modulators that have been approved for the treatment of some autoimmune diseases. Despite all of this progress, a deeper understanding of the differences between the mouse and human receptor is required to allow a safe translation of pre-clinical studies in efficient therapies. In this review, we discuss the role of CD28 in tolerance and autoimmunity and the clinical efficacy of drugs that block or enhance CD28 signaling, by highlighting the success and failure of pre-clinical studies, when translated to humans

A simple cytofluorimetric score may optimize testing for biallelic CEBPA mutations in patients with acute myeloid leukemia

Acute myeloid leukemia with biallelic mutation of CEBPA (CEBPA-dm AML) is a distinct good prognosis entity recognized by WHO 2016 classification. However, testing for CEBPA mutation is challenging, due to the intrinsic characteristics of the mutation itself. Indeed, molecular analysis cannot be performed with NGS technique and requires Sanger sequencing. The association of recurrent mutations or translocations with specific immunophenotypic patterns has been already reported in other AML subtypes. The aim of this study was the development of a specific cytofluorimetric score (CEBPA-dm score), in order to distinguish patients who are unlikely to harbor the mutation. To this end, the correlation of CEBPA-dm score with the presence of the mutation was analyzed in 50 consecutive AML patients with normal karyotype and without NPM1 mutation (that is mutually exclusive with CEBPA mutation). One point each was assigned for expression of HLA DR, CD7, CD13, CD15, CD33, CD34 and one point for lack of expression of CD14. OS was not influenced by sex, age and CEBPA-dm score. Multivariate OS analysis showed that CEBPA-dm (p < 0.02) and FLT3-ITD (p < 0.01) were the strongest independent predictors of OS. With a high negative predictive value (100%), CEBPA-dm score < 6 was able to identify patients who are unlikely to have the mutation. Therefore, the application of this simple score might optimize the use of expensive and time-consuming diagnostic and prognostic assessment in the baseline work up of AML patients