Postmortem Ultrastructural Analysis of the Retina from COVID-19 Deceased Patients.

PURPOSE: COVID-19 (coronavirus disease 2019) is an infectious disease caused by SARS-CoV-2, first reported in 2019 in Wuhan, China. Among the common complications is a pro-inflammatory and hypercoagulative response that compromises the vasculature among various organs. METHODS: In this report, we present the postmortem retinal findings of five patients observed by means of optical microscopy and transmission and scanning electron microscopy techniques. RESULTS: Clinical manifestations such as retinal hemorrhages and exacerbated inflammatory infiltrate, altered ultra structure with swollen mitochondria and pyknotic cells in both layers of the retina were observed in all analyzed eyes. CONCLUSION: Our data point to the fragility of this tissue in cases of severe COVID-19.

Hypoglycemia post bariatric surgery: drugs with different mechanisms of action to treat a unique disorder

ABSTRACT Postprandial hypoglycemia (PPH) is a complex and multifactorial complication of bariatric surgery (BS). PPH may cause severe symptoms or be asymptomatic. The treatment of this condition requires dietary changes, but severe cases require drug therapy. The number of therapeutic options is limited and are often associated with adverse side effects. Different classes of drugs have been used and tested, but the resolution of PPH remains a challenge for physicians and patients. In this review, we gathered articles on PPH after BS from PubMed searches (2001 to 2022) and focused on the main drugs tested for the treatment of this condition, such as acarbose, somatostatin analogues, type 2 sodium-glucose cotransporter inhibitors, calcium channel blockers, and liraglutide. Avexitide and glucagon pump are two new therapeutic options that have been recently tested. For the search, the terms "postbariatric hypoglycemia," "bariatric surgery," and "late dumping syndrome" were used. PPH after BS is a frequent condition that should always be evaluated after BS. Treatment should be individualized and the available therapeutic options may be useful based on the condition's pathophysiology.

Hypoglycemia post bariatric surgery: drugs with different mechanisms of action to treat a unique disorder.

Postprandial hypoglycemia (PPH) is a complex and multifactorial complication of bariatric surgery (BS). PPH may cause severe symptoms or be asymptomatic. The treatment of this condition requires dietary changes, but severe cases require drug therapy. The number of therapeutic options is limited and are often associated with adverse side effects. Different classes of drugs have been used and tested, but the resolution of PPH remains a challenge for physicians and patients. In this review, we gathered articles on PPH after BS from PubMed searches (2001 to 2022) and focused on the main drugs tested for the treatment of this condition, such as acarbose, somatostatin analogues, type 2 sodium-glucose cotransporter inhibitors, calcium channel blockers, and liraglutide. Avexitide and glucagon pump are two new therapeutic options that have been recently tested. For the search, the terms "postbariatric hypoglycemia," "bariatric surgery," and "late dumping syndrome" were used. PPH after BS is a frequent condition that should always be evaluated after BS. Treatment should be individualized and the available therapeutic options may be useful based on the condition's pathophysiology.

Terapia Notch, uma estratégia no tratamento do zumbido / Notch Therapy, a strategy in the treatment of tinnitus

Contexto: A Terapia Notch surgiu como estratégia promissora no controle do zumbido tonal. Trata-se de estratégia que utiliza a plasticidade neural para inibir as frequências laterais àquela do zumbido, equilibrando sinapses excitatórias e inibitórias e, por conseguinte, reduzindo a percepção e incômodo do zumbido. Objetivo: Avaliar a efetividade da Terapia Notch no controle do zumbido tonal. Material e métodos: Trata-se de sinopse baseada em evidências. Procedeu-se à busca por estudos que associavam zumbido e Terapia Notch em quatro bases eletrônicas de dados: Cochrane - Central de Registros de Ensaios Clínicos - CENTRAL (2022), PubMed (1966-2022), Portal BVS (1982-2022) e Embase (1974- 2022). Dois pesquisadores independentemente extraíram os dados e avaliaram a qualidade dos estudos para a síntese. O desfecho primário de análise envolveu a melhora clínica do zumbido. Resultados: Foram encontradas 538 referências. Seis estudos foram incluídos (n = 233 participantes). Discussão: A literatura apresenta poucos estudos clínicos de avaliação da terapia Notch para zumbido. Trata-se de ensaios clínicos com amostragem reduzida e heterogeneidade alta. Embora o nível de evidência seja ainda muito limitado, todos esses estudos concluem que a terapia Notch pode ser efetiva no controle do zumbido tonal. Conclusões: A terapia Notch pode trazer benefícios no controle do zumbido tonal, mas novos ensaios clínicos de qualidade e bom delineamento são necessários para maior robustez da evidência.

Novel Functions of Integrins as Receptors of CD154: Their Role in Inflammation and Apoptosis.

CD154, an inflammatory mediator also known as CD40 ligand, has been identified as a novel binding partner for some members of the integrin family. The αIIbß3, specifically expressed on platelets, was the first integrin to be described as a receptor for CD154 after CD40. Its interaction with soluble CD154 (sCD154) highly contributes to thrombus formation and stability. Identifying αIIbß3 opened the door for investigating other integrins as partners of CD154. The αMß2 expressed on myeloid cells was shown capable of binding CD154 and contributing as such to cell activation, adhesion, and release of proinflammatory mediators. In parallel, α5ß1 communicates with sCD154, inducing pro-inflammatory responses. Additional pathogenic effects involving apoptosis-preventing functions were exhibited by the CD154-α5ß1 dyad in T cells, conferring a role for such interaction in the survival of malignant cells, as well as the persistence of autoreactive T cells. More recently, CD154 receptors integrated two new integrin members, αvß3 and α4ß1, with little known as to their biological significance in this context. This article provides an overview of the novel role of integrins as receptors of CD154 and as critical players in pro-inflammatory and apoptotic responses.

SGLT2 Inhibition with Empagliflozin as a Possible Therapeutic Option for Postprandial Hypoglycemia After Bariatric Surgery.

PURPOSE: Since SGLT2 inhibitors may reduce postprandial hyperglycemia, this study aimed to evaluated whether empagliflozin might be useful in the treatment of postprandial hypoglycemia (PPH) postbariatric surgery (BS). PATIENTS AND METHODS: Fourteen patients who underwent BS, nine without type 2 diabetes and five with diabetes before surgery and in remission after surgery, were included. Seven of them presented symptoms of PPH (hypoglycemic group; HG) and seven were asymptomatic (nonhypoglycemic group (NHG)). A meal tolerance test was performed before and after administration of a daily dose of empagliflozin (EMPA) 25 mg for 3 days. Plasma glucose and serum insulin levels were measured. RESULTS: In HG, compared with NHG, in the basal test, the area under the curve (AUC) of plasma glucose levels (AUCgly) was smaller (158.3 ± 25.3 vs 276.6 ± 79.2 mg h dL-1; p = 0.001) while the AUC of insulin levels (AUCins) did not differ, leading to a higher AUCins/AUCgly ratio (0.79 ± 0.46 vs 0.38 ± 0.20; p = 0.055) and a lower HOMA-IR (0.92 ± 0.22 vs 1.75 ± 0.77; p = 0.030). The HG after EMPA, but not the NHG, showed significant increases in glycemia leading to greater AUCgly (158.0 ± 25.3 to 197.2 ± 51.6 mg h dL-1; p = 0.043) without significant changes in AUCins. HOMA-IR increased only in the HG (0.92 ± 0.20 vs 1.61 ± 0.30; p = 0.025) and, when both groups were analyzed together, both before and post EMPA, a significant correlation was found between HOMA-IR and AUCgly values (r = 0.594; p = 0.002). CONCLUSION: Our results suggest that empagliflozin increased glycemic levels in patients with PPH possibly through increases in hepatic glucose production.

Retinal autofluorescence findings after COVID-19.

The main purpose of this study was to investigate the presence of retinal autofluorescence findings in COVID-19 patients. Observational study conducted in São Paulo in 2020. Demographic, medical history, and concomitant events, as well as medications used, hospitalization details, and laboratory test results, were obtained. Patients underwent eye examination and multimodal imaging, including color, red-free, autofluorescence fundus photography and optical coherence tomography. Eighteen patients had autofluorescence findings (6 females; average age 54 years, range 31 to 86 years; 26 eyes). Hyper-autofluorescence findings were present in 6 patients, Hypo-autofluorescence in 14 patients, and 6 patients had mixed pattern lesions. Retinal autofluorescence abnormalities were present in COVID-19 patients and may be secondary to primary or secondary changes caused by the SARS-CoV-2.

Monoclonal Antibody Targeting the CD154 Cleavage Site Inhibits CD40-Dependent and -Independent Cleavage of CD154 from the Cell Surface.

In addition to the membrane-bound molecule, soluble CD154 (sCD154) is also detected at high levels in the medium of activated T cells and platelets and in the serum of patients suffering from different inflammatory diseases. This sCD154 is the result of cleavage of the full-length molecule between the glutamic acid residue at position 112 (E112) and methionine at position 113 (M113) and can be derived from the intracellular milieu and from cleavage of cell surface molecules. We have recently reported that substitution of both E112 and M113 by alanine inhibits intracellular and CD40-induced membrane cleavage of CD154 and procures to CD154 an increased biological function as compared with cleavable CD154. Thus, in this study, and in the aim of developing tools inhibiting cleavage of CD154 from the cell surface, we generated a panel of anti-human CD154 mAbs. One of the derived mAbs that did not alter the binding of sCD154 to CD40, named in this study Clone 8 mAb, totally lost its binding activity against cells expressing CD154 mutated at its E112 and M113 residues. Treatment with Clone 8 mAb was shown to completely abolish CD40-dependent and -independent cleavage of CD154 from the cell surface. Our study is highlighting the development and characterization of an innovative therapeutic tool capable of inhibiting the release/cleavage of CD154 from cells and thus maintaining its availability on the cell surface and the high probably of increasing its potency as an activator of CD40-induced responses.

COVID-19 Retinal Findings in Patients Admitted to Intensive Care Units and Wards.

The main purpose of this study was to investigate ocular clinical findings in patients with confirmed COVID-19 infection, of various levels of disease severity, who required mechanical ventilation and admission to intensive care units or specialized wards. Longitudinal, observational study conducted from March 2020 to June 2020. Color fundus and red-free photography were performed in both eyes following pupillary dilation. 104 participants were recruited from 2 different centers: 60 (58%) from the Hospital Municipal de Barueri intensive care unit (ICU) and 44 (42%) from specialized wards for patients with COVID-19 at the Hospital São Paulo. 21.9% presented with eye lesions, in 3% these lesions were vision compromising. Our results have shown similar rate of intraocular lesions in patients in both the ward or intensive care unit, regardless of medication use, including anticoagulant drugs.

CD154 Resistant to Cleavage from Intracellular Milieu and Cell Surface Induces More Potent CD40-Mediated Responses.

In addition to the membrane-bound form, CD154 also exists as a soluble molecule originating from an intracellular and membrane cleavage. We have previously shown that CD154 cleavage from T cell surface is mediated by CD40 and involves the action of ADAM10/ADAM17 enzymes. In the aim of defining the importance of CD154 maintained on cell surface, we generated a CD154 mutated at the cleavage site. Our data show that the double mutation of E112 and M113 residues of CD154 abolishes its spontaneous release and the CD40-mediated cleavage from cell surface but does not affect its binding to CD40. We also demonstrated that both the release of CD154 from the intracellular milieu and its CD40-mediated cleavage from cell surface are highly dependent on ADAM10/ADAM17 enzymes. The CD154-EM mutant was shown capable of inducing a more prominent apoptotic response in susceptible B cell lines than the wild-type (WT) form of the molecule. In addition, human B cells cultured in the presence of the CD154-EM mutant exhibited upregulated proliferative responses compared with the CD154-WT. The CD154-EM mutant was also shown to trigger differentiation of human B cells, reflected by an increased Ig production, more significantly than CD154-WT. Thus, our data strongly suggest that cleavage-resistant CD154 is a more prominent stimulant than the cleavable form of the molecule. Therefore, a maintained expression of CD154 on cell membrane and a disturbed cleavage of the molecule could be a mechanism by which CD154 is involved in some pathological conditions and should be revisited.

CD154 inhibits death of T cells via a Cis interaction with the α5ß1 integrin.

CD154 plays a major role in the pathogenesis of several autoimmune and inflammatory diseases. In addition to CD40, soluble CD154 (sCD154) binds to other receptors namely αIIbß3, αMß2, α5ß1 and αvß3 integrins. We have previously reported that binding of sCD154 to α5ß1 integrin expressed on several human T cell lines is capable of inhibiting Fas-induced cell death. In the current study, we show that such effect of the sCD154/α5ß1 interaction is not restricted to the cell death response induced by Fas but could also be exhibited toward other death signals such as TRAIL and TNF- α. We also demonstrate that sCD154 is capable of inhibiting Fas-mediated death of human activated T cells, more importantly of CD4+ than CD8+ T ones. Our data also show that membrane-bound CD154 and α5ß1 integrin expressed on the surface of distinct cells failed to influence cell death responses. However, when membrane-bound CD154 and α5ß1 are expressed on the surface of same cell, their interaction was capable of down regulating cell death. CD154 was shown to co-localize with the α5ß1 integrin on the surface of these cells. These data strongly suggest a cis-type of interaction between CD154 and α5ß1 when both are expressed on the same cell surface, rather than a trans-interaction which usually implicates the ligand and its receptor each expressed on the surface of a distinct cell. Taken together, these findings add to the list of roles through which CD154 is contributing to the pathogenesis of autoimmune-inflammatory diseases, i.e. by protecting T cells from death and enhancing their survival.

Aspirin Reduces the Potentiating Effect of CD40L on Platelet Aggregation via Inhibition of Myosin Light Chain.

Background Antiplatelet therapy with aspirin (acetylsalicylic acid [ASA]) is less efficient in some coronary patients, which increases their risk of developing thrombosis. Elevated blood levels of thromboinflammatory mediators, like soluble CD40L (sCD40L), may explain such variabilities. We hypothesized that in the presence of elevated levels of sCD40L, the efficacy of ASA may vary and aimed to determine the effects of ASA on CD40L signaling and aggregation of platelets. Methods and Results The effects of ASA on CD40L-treated human platelets, in response to suboptimal concentrations of collagen or thrombin, were assessed at levels of aggregation, thromboxane A2 secretion, and phosphorylation of p38 mitogen-activated protein kinase, nuclear factor kappa B, transforming growth factor-ß-activated kinase 1, and myosin light chain. sCD40L significantly elevated thromboxane A2 secretion in platelets in response to suboptimal doses of collagen and thrombin, which was reversed by ASA. ASA did not inhibit the phosphorylation of p38 mitogen-activated protein kinase, nuclear factor kappa B, and transforming growth factor-ß-activated kinase 1, with sCD40L stimulation alone or with platelet agonists. sCD40L potentiated platelet aggregation, an effect completely reversed and partially reduced by ASA in response to a suboptimal dose of collagen and thrombin, respectively. The effects of ASA in sCD40L-treated platelets with collagen were related to inhibition of platelet shape change and myosin light chain phosphorylation. Conclusions ASA does not affect platelet sCD40L signaling but prevents its effect on thromboxane A2 secretion and platelet aggregation in response to collagen, via a mechanism implying inhibition of myosin light chain. Targeting the sCD40L axis in platelets may have a therapeutic potential in patients with elevated levels of sCD40L and who are nonresponsive or less responsive to ASA.

Beta1 integrin blockade overcomes doxorubicin resistance in human T-cell acute lymphoblastic leukemia.

Growing evidence indicates that cell adhesion to extracellular matrix (ECM) plays an important role in cancer chemoresistance. Leukemic T cells express several adhesion receptors of the ß1 integrin subfamily with which they interact with ECM. However, the role of ß1 integrins in chemoresistance of T-cell acute lymphoblastic leukemia (T-ALL) is still ill defined. In this study, we demonstrate that interactions of human T-ALL cell lines and primary blasts with three-dimensional matrices including Matrigel and collagen type I gel promote their resistance to doxorubicin via ß1 integrin. The blockade of ß1 integrin with a specific neutralizing antibody sensitized xenografted CEM leukemic cells to doxorubicin, diminished the leukemic burden in the bone marrow and resulted in the extension of animal survival. Mechanistically, Matrigel/ß1 integrin interaction enhanced T-ALL chemoresistance by promoting doxorubicin efflux through the activation of the ABCC1 drug transporter. Finally, our findings showed that Matrigel/ß1 interaction enhanced doxorubicin efflux and chemoresistance by activating the FAK-related proline-rich tyrosine kinase 2 (PYK2) as both PYK2 inhibitor and siRNA diminished the effect of Matrigel. Collectively, these results support the role of ß1 integrin in T-ALL chemoresistance and suggest that the ß1 integrin pathway can constitute a therapeutic target to avoid chemoresistance and relapsed-disease in human T-ALL.

CD40L Priming of Platelets via NF-κB Activation is CD40- and TAK1-Dependent.

Background CD40 ligand (CD40L) is a thromboinflammatory molecule that predicts cardiovascular events. CD40L is a strong activator of nuclear factor kappa B (NF-κB) in platelets that primes and enhances platelet activation in response to thrombotic stimuli. In addition to its classical receptor CD40, CD40L binds αIIbß3, α5ß1, and αMß2 in various cell types. However, the function of the different CD40L receptors on platelets remains unexplored. The present study aims to identify the receptors of CD40L, involved in platelet NF-κB activation, their downstream signaling and their implication in platelet aggregation. Methods and Results We showed that platelets express CD40, αIIbß3, and α5ß1 and release CD40L in response to sCD40L stimulation. sCD40L alone dose-dependently induced platelet NF-κB activation; this effect was absent in CD40-/- mouse platelets and inhibited by the CD40 blockade, but was unaffected by the αIIbß3 or α5ß1 blockade in human platelets. sCD40L/CD40 axis activates transforming growth factor-ß-activated kinase 1 upstream of NF-κB. In functional studies, sCD40L alone did not affect platelet aggregation but potentiated the aggregation response in the presence of suboptimal doses of thrombin; this effect was abolished by CD40, transforming growth factor-ß-activated kinase 1, and NF-κB inhibitors. Conclusions CD40L primes platelets via signaling pathways involving CD40/transforming growth factor-ß-activated kinase 1/NF-κB, which predisposes platelets to enhanced activation and aggregation in response to thrombotic stimuli.

Corrigendum: Semaphorin 4C: A Novel Component of B-Cell Polarization in Th2-Driven Immune Responses.

[This corrects the article on p. 558 in vol. 7, PMID: 28003812.].

Peripherally Generated Foxp3+ Regulatory T Cells Mediate the Immunomodulatory Effects of IVIg in Allergic Airways Disease.

IVIg is widely used as an immunomodulatory therapy. We have recently demonstrated that IVIg protects against airway hyperresponsiveness (AHR) and inflammation in mouse models of allergic airways disease (AAD), associated with induction of Foxp3+ regulatory T cells (Treg). Using mice carrying a DTR/EGFP transgene under the control of the Foxp3 promoter (DEREG mice), we demonstrate in this study that IVIg generates a de novo population of peripheral Treg (pTreg) in the absence of endogenous Treg. IVIg-generated pTreg were sufficient for inhibition of OVA-induced AHR in an Ag-driven murine model of AAD. In the absence of endogenous Treg, IVIg failed to confer protection against AHR and airway inflammation. Adoptive transfer of purified IVIg-generated pTreg prior to Ag challenge effectively prevented airway inflammation and AHR in an Ag-specific manner. Microarray gene expression profiling of IVIg-generated pTreg revealed upregulation of genes associated with cell cycle, chromatin, cytoskeleton/motility, immunity, and apoptosis. These data demonstrate the importance of Treg in regulating AAD and show that IVIg-generated pTreg are necessary and sufficient for inhibition of allergen-induced AAD. The ability of IVIg to generate pure populations of highly Ag-specific pTreg represents a new avenue to study pTreg, the cross-talk between humoral and cellular immunity, and regulation of the inflammatory response to Ags.

Constitutively active Stat5b signaling confers tolerogenic functions to dendritic cells of NOD mice and halts diabetes progression.

Defects in dendritic cells (DCs) development and function lead to autoimmune disorders. Autoimmune diabetes in humans and NOD mice results from a breakdown of self-tolerance, ending in T cell-mediated ß-cell destruction. DCs dysfunction in NOD mice results in part from a defect in the JAK-STAT5 signaling pathway associated with the idd4 susceptibility locus. The involvement of Stat5b in DCs tolerogenic functions remains unknown. We have generated transgenic mice (NOD.CD11cStat5b-CA) expressing a constitutively active form of the Stat5b gene (Stat5b-CA) under control of CD11c promoter. All NOD.CD11cStat5b-CA mice were protected against diabetes. Protection was associated with an increased in the pool and suppressive function of Tregs, a promotion of Th2 and Tc2 immune response and a decreased percentage of CD8+ T cells. Splenic DCs of NOD.CD11cStat5b-CA mice acquired a mature phenotype, promoted and induced better conversion of CD4+CD25-Foxp3- T cells into Tregs (CD4+CD25+Foxp3+ T cells) than DCs of NOD mice. Stat5b-CA.DC-educated CD4+CD25- T cells delayed diabetes onset whereas Stat5b-CA.DC-educated Tregs blocked ongoing diabetes in 8-10 weeks old NOD recipient mice. Importantly, injection of Stat5b.CA.DC to 8-10-week old NOD mice halted diabetes progression and educated their splenocytes to loose their diabetogenic potential when transferred to NOD.SCID mice. Our work is the first to report that an active form of Stat5b restored DCs tolerogenic functions that re-educated Tregs to re-establish and to sustain long-term protective immune response against diabetes in NOD mice.

Semaphorin 4C: A Novel Component of B-Cell Polarization in Th2-Driven Immune Responses.

BACKGROUND: Semaphorins are important molecules in embryonic development and multiple semaphorins have been identified as having key roles in immune regulation. To date, there is little known about Semaphorin 4C (Sema4C) in immune biology. We report for the first time that Sema4C is inducible in human and murine B-cells and may be important for normal B-cell development. METHODS: Human tonsillar B-cells were studied following activation via anti-CD40 antibodies in the presence or absence of representative Th1, Th2, and regulatory cytokines. Murine B-cells from WT and Sema4C-/- mice were similarly stimulated. B-cell phenotyping in WT and Sema4C mutant mice was performed by flow cytometry and lymphoid architecture was studied by immunohistochemistry. Sema4C expression and synapse formation were analyzed by confocal microscopy. RESULTS: Gene array studies performed on human tonsillar B-cells stimulated to produce IgE revealed that Sema4C was among the top genes expressed at 24 h, and the only semaphorin to be increased under Th2 conditions. Validation studies demonstrated that human and murine B-cells expressed Sema4C under similar conditions. Sema4C-/- mice had impaired maturation of B-cell follicles in spleens and associated decreases in follicular and marginal zone B-cells as well as impaired IgG and IgA production. In keeping with a potential role in maturation of B-cells, Sema4C was expressed predominantly on CD27+ human B-cells. Within 72 h of B-cell activation, Sema4C was localized to one pole in a synapse-like structure, in association with F-actin, B-cell receptor, and Plexin-B2. Cell polarization was impaired in Sema4C-/- mice. CONCLUSION: We have identified a novel immune semaphorin induced in human and murine B-cells under Th2 conditions. Sema4C appears to be a marker for human memory B-cells. It may be important for B-cell polarization and for the formation of normal splenic follicles.

The Interaction of CD154 with the α5ß1 Integrin Inhibits Fas-Induced T Cell Death.

CD154, a critical regulator of the immune response, is usually associated with chronic inflammatory, autoimmune diseases as well as malignant disorders. In addition to its classical receptor CD40, CD154 is capable of binding other receptors, members of the integrin family, the αIIbß3, αMß2 and α5ß1. Given the role attributed to integrins and particularly the ß1 integrins in inhibiting apoptotic events in normal as well as malignant T cells, we were highly interested in investigating the role of the CD154/α5ß1 interaction in promoting survival of malignant T cells contributing as such to tumor development and/or propagation. To support our hypothesis, we first show that soluble CD154 binds to the T-cell acute lymphoblastic leukemia cell line, Jurkat E6.1 in a α5ß1-dependent manner. Binding of soluble CD154 to α5ß1 integrin of Jurkat cells leads to the activation of key survival proteins, including the p38 and ERK1/2 mitogen-activated protein kinases (MAPKs), phosphoinositide 3 kinase (PI-3K), and Akt. Interestingly, soluble CD154 significantly inhibits Fas-mediated apoptosis in T cell leukemia-lymphoma cell lines, Jurkat E6.1 and HUT78 cells, an important hallmark of T cell survival during malignancy progression. These anti-apoptotic effects were mainly mediated by the activation of the PI-3K/Akt pathway but also involved the p38 and the ERK1/2 MAPKs cascades. Our data also demonstrated that the CD154-triggered inhibition of the Fas-mediated cell death response was dependent on a suppression of caspase-8 cleavage, but independent of de novo protein synthesis or alterations in Fas expression on cell surface. Together, our results highlight the impact of the CD154/α5ß1 interaction in T cell function/survival and identify novel targets for the treatment of malignant disorders, particularly of T cell origin.

Ochratoxin A mediates MAPK activation, modulates IL-2 and TNF-α mRNA expression and induces apoptosis by mitochondria-dependent and mitochondria-independent pathways in human H9 T cells.

Ochratoxin A (OTA) is a natural fungal secondary metabolite that contaminates food and animal feed. Human exposure and involvement of this mycotoxin in several pathologies have been demonstrated worldwide. We investigated OTA immunotoxicity on H9 cells, a human cutaneous CD4+ T lymphoma cell line. Cells were treated with 0, 1, 5, 10, and 20 µM OTA for up to 24 hr. Western blotting revealed increased phosphorylation of all three major mitogen-activated protein kinases (extracellular signal-regulated kinase, c-Jun amino-terminal kinase, p38). OTA triggered mitochondrial transmembrane potential loss and caspase-3 activation. The 24-hr OTA treatment caused marked changes in cell morphology and DNA fragmentation, suggesting the occurrence of apoptotic events that involved a mitochondria-dependent pathway. Moreover, OTA triggered significant modulation of survivin, interleukin 2 (IL-2) and tumor necrosis factor α (TNF-α): mRNA expression of survivin and IL-2 were decreased, while TNF-α was increased. OTA also caused caspase-8 activation in a time-dependent manner, which evokes the death receptor pathway activation; we suspect that this occurred via the autocrine pro-apoptotic effect of TNF-α on H9 cells.