Neutralization Of TNF-α Research Articles

Abstract 17228: Rassf1A Inhibits Akt Activation in Cardiac Fibroblasts and Protects Against Ischemia Reperfusion Injury in the Heart

Our previous work demonstrated Rassf1A to be a critical mediator of Mst1 activation, the chief component of the mammalian Hippo pathway, in heart failure. In the setting of ischemia/reperfusion (I/R) injury, Mst1 is robustly activated and promotes injury in the heart; however, its regulation remains unclear. Using genetically modified mice in which expression of Rassf1A is altered in a cell type-specific manner, we demonstrate that systemic deletion of rassf1a -/- (KO) does not alter infarct size (36±4% vs 33±3%) or cardiac myocyte apoptosis (1.7±0.2% vs 2.1±0.4%) following I/R versus WT. Conversely, mice harboring deletion of rassf1a in cardiac myocytes ( rassf1a flox/flox αMHC-Cre, CKO) have smaller infarcts (23±2 vs 38±3%, p<0.05) and less apoptosis (0.9±0.2 vs 2.0±0.2%, p<0.05) after I/R. Importantly, attenuation of Mst1 activation in ventricular homogenates was observed in both deletion models, implicating Rassf1A as a positive regulator of Mst1 during I/R. Langendorff global I/R injury yielded similar results - no protection in KO, yet significant protection in CKO hearts versus control mice, suggesting that native cardiac cells are sufficient to mediate this response. Using isolated cardiac fibroblast cultures we determined that Rassf1A negatively regulates activation of Akt in response to oxidative stress. Further, knockdown of endogenous Rassf1A causes increased NF-κB activity, a response mediated by Akt. A candidate molecule screen found exaggerated TNF-α expression in non-myocytes of KO hearts compared to WT (4.8±0.7fold, p<0.05), whereas TNF-α expression was attenuated in CKO hearts (reduced 65±8% vs control, p<0.05). Finally, WT and KO mice were administered TNF-α neutralizing antibody or control IgG and subjected to I/R. KO hearts treated with TNF-α Ab, but not IgG, had reduced infarcts (19±4% vs 34±5%, p<0.05), but no significant reduction in infarct size was observed in WT mice given TNF-α Ab. Taken together these data suggest that TNF-α blockade prevents the deleterious consequences of Rassf1A deletion in non-myocytes while unmasking the protective effect of Rassf1A deletion in cardiac myocytes following I/R. Further, these results demonstrate the importance of non-myocytes in modulating cardiac myocyte survival and I/R injury

Fusion of HSA influences TNF-α neutralizing activity of shTNFRs

Soluble human tumor necrosis factor receptors (shTNFRI and shTNFRII) are antagonists of tumor necrosis factor-α (TNF-α) and are under clinical investigation as therapy for autoimmune diseases and transplant rejection. However, shTNFRI and shTNFRII are limited for clinical usage because of their short half-lives in vivo. Recombinant TNF-α receptors (infliximab and etanercept) are used in treatment of rheumatoid arthritis and Crohn's disease but are also being tested for a number of other autoimmune diseases. Human serum albumin (HSA) has been used to construct long-acting fusion proteins. Here, we report the effect of fusion of HSA with shTNFRI and with shTNFRII on shTNFR's neutralizing activity against TNF-α. HSA fusion proteins were separately expressed in Pichia pastoris. Purified recombinant shTNFRI-HSA, HSA-shTNFRI and HSA-shTNFRII could block the cytolytic activity of TNF-α in L929 cells, and the fusion at N-terminus of shTNFRI could result in larger degree of activity decline than that at the C-terminus. Activity of three fusion proteins was much weaker than etanercept, which demonstrated that fusion of HSA significantly influenced TNF-α neutralizing activity of shTNFRs. Compared with Fc fragment, HSA fusion technology may therefore not be an ideal strategy in development of long-acting shTNFRs protein drugs.

AZD9773, a novel anti-TNFα immune Fab in development for severe sepsis and septic shock: demonstration of safety and efficacy in a murine CLP sepsis model

TNFα is thought to play a central role in the pathogenesis of sepsis and septic shock. AZD9773 is an ovine polyclonal anti-human TNFα immune Fab comprising TNFα-directed and nonspecific Fab populations. AZD9773 potency and pharmacokinetic attributes such as a shorter half-life distinguish it from anti-TNF monoclonal antibodies, which have been assessed previously in clinical sepsis models. Here we explore the preclinical safety/efficacy of AZD9773 in a mouse cecal ligation puncture (CLP) model. There are currently no reports of anti-TNF agent efficacy in mouse CLP; rather, TNFα neutralization is associated with minimal/no effect or increased mouse mortality. As AZD9773 is differentiated from other anti-TNFα agents based on neutralizing potency and pharmacokinetic attributes, we studied both the safety and efficacy of this product in mouse CLP models.

Tumor Necrosis Factor-α and Muc2 Mucin Play Major Roles in Disease Onset and Progression in Dextran Sodium Sulphate-Induced Colitis

The sequential events and the inflammatory mediators that characterize disease onset and progression of ulcerative colitis (UC) are not well known. In this study, we evaluated the early pathologic events in the pathogenesis of colonic ulcers in rats treated with dextran sodium sulfate (DSS). Following a lag phase, day 5 of DSS treatment was found clinically most critical as disease activity index (DAI) exhibited an exponential rise with severe weight loss and rectal bleeding. Surprisingly, on days 1-2, colonic TNF-α expression (70-80-fold) and tissue protein (50-fold) were increased, whereas IL-1β only increased on days 7-9 (60-90-fold). Days 3-6 of DSS treatment were characterized by a prominent down regulation in the expression of regulatory cytokines (40-fold for IL-10 and TGFβ) and mucin genes (15-18 fold for Muc2 and Muc3) concomitant with depletion of goblet cell and adherent mucin. Remarkably, treatment with TNF-α neutralizing antibody markedly altered DSS injury with reduced DAI, restoration of the adherent and goblet cell mucin and IL-1β and mucin gene expression. We conclude that early onset colitis is dependent on TNF-α that preceded depletion of adherent and goblet cell mucin prior to epithelial cell damage and these biomarkers can be used as therapeutic targets for UC.

Abstract A4: Hodgkin and Reed-Sternberg cells secrete soluble factors to modulate endothelial cell-T cell interactions in classical Hodgkin lymphoma

Abstract Introduction: Classical Hodgkin lymphoma (CHL) is characterized by the presence of a minority of malignant Hodgkin and Reed-Sternberg cells (H-RS cells) surrounded by an abundant mixed inflammatory infiltrate that includes CD4+ T helper 2 cells, regulatory T cells and CD8+ cytotoxic T cells. The mechanisms exploited by HRS cells to influence T cell recruitment into the involved lymph nodes are still unknown. Objective: The aim of this study is to elucidate whether H-RS cells can induce endothelial cell activation to modulate T cell recruitment in CHL. Procedures: Fresh cell culture supernatant (C/S) from the H-RS cell line, KM-H2, was used to stimulate endothelial cells (EC) in-vitro. Controls were EC incubated in medium alone; or with 10ng/ml TNF-α Up-regulation of adhesion molecule expression was assessed by ELISA and FACS. Using the transwell migration system and the parallel plate flow chamber apparatus respectivel, the ability of these stimulated EC to support T cell interactions in-vitro was assessed under static and defined flow conditions. Signaling pathways involved in C/S induced EC activation were examined by western blotting. Results: KM-H2 C/S-stimulated EC up-regulate ICAM-1, VCAM-1 and E-selectin to levels comparable to those of TNF-α-stimulated EC. Both C/S-stimulated EC and TNF-α stimulated-EC support naïve and memory T-cell interactions under defined flow conditions. Furthermore, both CD4+ naïve and memory T cell demonstrated enhanced transmigration across C/S-stimulated EC monolayers in response to SDF-1α, as compared to TNF-α-stimulated or unstimulated EC. The activation of EC by KM-H2 C/S is dependent on the NFkB pathway. Blocking of p65 nuclear translocation by the specific IκBα phosphorylation inhibitor (BAY11-8075) abrogated the stimulatory effect of C/S on EC. Phosphorylation of ERK, p38 and JNK were also detected in the KM-H2 C/S stimulated EC. Intracytoplasmic expression of TNF-α was detected in KM-H2 cells. The bioactivity assay showed that the TNF-α sensitive cell line, L929 is sensitive to KM-H2 C/S. However, treatment of cells with TNF-α neutralizing antibody did not effectively prevent L929 cell death, nor inhibit the stimulatory effect of KM-H2 C/S on EC. Conclusion: Our data suggest that the malignant Hodgkin and Reed-Sternberg cells secrete soluble mediators that modulate endothelial cell function and influence recruitment of T cells into the cHL lesion. While the C/S induced EC activation is dependent on the NFkB pathway, our data suggest that the dominant mediator involved is not TNF-α. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr A4.

Infections in patients with rheumatoid arthritis receiving anti-cytokine therapy: biological mechanisms and clinical aspects

Different animal studies show that several proinflammatory cytokines are essential for natural resistance to specific infections, particularly versus intracellular organisms. However, uncontrolled overproduction of some proinflammatory cytokines, in diseases such as rheumatoid arthritis, can be just as dangerous to the host as the absence of the same cytokines. Reduction in the production and/or activities of proinflammatory cytokines in rheumatoid arthritis remains a therapeutic objective for many patients. The tumour necrosis factor-alpha (TNF-alpha) blockers infliximab, etanercept and adalimumab and the recombinant interleukin 1 (IL-1) receptor antagonist anakinra are effective in patients with active rheumatoid arthritis. However, there is a growing body of clinical evidence that neutralization of TNF-alpha is associated with an increased risk of opportunistic infections, including mycobacterial diseases. Blockade of IL-1 activity with the IL-1 receptor antagonist (IL-1Ra) appears, at present, to be relatively safe. Postmarketing experience and pharmacovigilance programs are necessary to determine the overall safety profile of the new agents. At this time, treating physicians must weigh carefully the benefits of biologics against their safety, particularly in patients at risk of infection.

Macrophage‐induced expression and release of matrix metalloproteinase 1 and 3 by human preadipocytes is mediated by IL‐1β via activation of MAPK signaling

Obesity is associated with a chronic low-grade inflammation and increased macrophage infiltration in adipose tissue. Matrix metalloproteinases (MMPs) are involved in adipose tissue remodeling and inflammatory responses in obesity. This study investigated whether macrophage-derived factors modulate expression and secretion of MMP1 and MMP3 in human preadipocytes. The potential mediators and signaling pathways were also explored. MMP1 and MMP3 were primarily expressed and secreted by preadipocytes and dramatically reduced post-differentiation. Preadipocytes were incubated with RPMI 1640 medium (control) or THP-1 macrophage-conditioned (MC) medium (25% and 100%) for 24 h. MC medium markedly increased mRNA levels of MMP1 (up to 122-fold) and MMP3 (up to 59-fold), as well as protein release of MMP1 (up to 378-fold) and MMP3 (up to 10-fold) in a dose-dependent manner. Treatment with IL-1β or TNFα, the major products of macrophages, also induced MMP1 and MMP3 secretion by preadipocytes. Neutralizing IL-1β abolished the induction of MMP1 and MMP3 in preadipocytes by MC medium while the effects of TNFα neutralization were modest. Furthermore, MC medium or IL-1β led to the phosphorylation of p38, ERK and JNK MAPKs. Inhibition of p38, ERK and JNK reversed the stimulatory effects of MC or IL-1β on MMP1 and MMP3 production. MC medium and IL-1β also activated NF-κB p65 whereas reduced IκBα protein expression in preadipocytes. These results suggest that macrophage accumulation in adipose tissue has a central role in stimulating MMP1 and MMP3 production by preadipocytes, and this is partially mediated by IL-1β via activation of the MAPK and NF-κB signaling pathways.

Effects of mycobacterial infection on proliferation of hematopoietic precursor cells

Bacterial infection can affect hematopoietic precursor cells in bone marrow, because the infected tissues produce various cytokines and chemokines. Little is known about hematopoietic precursor cells, including hematopoietic stem cells and their progenitors, during mycobacterial infection. Here, we showed that mycobacterial infections result in the expansion of not only the lin-c-kit+sca-1+ (LKS+) cell population, but also granulocyte–monocyte progenitor cells in a chronic murine tuberculosis model. Interestingly, stimulation of LKS+ cells with attenuated Mycobacterium tuberculosis H37Ra culture filtrate (RaCF) was significantly stronger than that by virulent H37Rv culture filtrate (RvCF). Lower TNF-α and IL-6 levels were observed in RvCF-stimulated bone marrow cells. Neutralization of TNF-α or IL-6 in RaCF-stimulated bone marrow cells markedly suppressed LKS+ cell clonal expansion. Additionally, numbers of LKS+ cells were lower in TLR2 −/− and MyD88 −/− mice after mycobacterial infection. Taken together, LKS+ cell proliferation related to mycobacterial virulence may be related to the secretion of TNF-α and IL-6 associated with TLR signaling. Expansion of hematopoietic progenitor cells may, therefore, play an important role during mycobacterial infection.

Does functional MRI convincingly explain the fast effect of TNF-α blockade?

Hess et al. (1) recently reported that nociceptive stimuli-activated brain areas, revealed by functional MRI (fMRI), were significantly reduced within 24 h after an infusion of a monoclonal antibody to TNF-α in their patients with rheumatoid arthritis (RA). Together with evidence from accompanying animal experiments, the authors concluded that neutralization of TNF-α could rapidly inhibit pain responses in the CNS. Although the investigation represented an important attempt to understand fully the fast therapeutical effect of TNF-α blockade, the conclusion should be accepted with caution. In my opinion, two major concerns with fMRI experiments in the patients need to be adequately addressed.

Infliximab alleviates inflammation and ex vivo airway hyperreactivity in asthmatic E3 rats

Tumor necrosis factor-α (TNF-α) has been implicated in the pathogenesis of asthma, and neutralization of TNF-α is an effective therapy for inflammatory diseases. The present study tested the idea that a TNF-α antibody, infliximab, may be useful in the management of asthma. E3 rats were immunized with ovalbumin (OVA)/alum and received infliximab intra-peritoneally. Two weeks later, OVA-PBS was instilled intranasally daily for 7 days. Bronchoalveolar lavage fluids (BALFs), serum and lung homogenates were collected for analysis of cells and inflammatory mediators. Contractile responses of lobar-bronchus segments to agonists were functionally tested. Pulmonary tissues were investigated using histological examination. The results showed that the sensitized 'model E3 rats' exhibited an increase in the total amount of inflammatory cells, primarily eosinophils, in BALF and pulmonary tissue, as well as epithelial damage. Serum levels of IgE increased and so did the levels of nitric oxide, inducible nitric oxide synthase, TNF-α and IL-4, IL-5 and IL-13 in lung homogenate and serum. Furthermore, the contractile responses in bronchi induced by endothelin-1, sarafotoxin 6c and bradykinin increased and isoprenaline-induced relaxations decreased. All these changes induced by the sensitization procedure were reduced by the infliximab treatment. The results suggest that infliximab prevents the development of local airway inflammation and antagonizes changes of the bronchial smooth muscle receptor phenotype, thereby blocking the development of airway smooth muscle hyperreactivity of asthmatic rats.

P65/RelA-Ser529 NF-κB subunit phosphorylation induces autophagic astroglial death (Clasmatodendrosis) following status epilepticus.

Clasmatodendrosis is an irreversible astroglial degenerative change, which includes extensive swelling and vacuolization of cell bodies and disintegrated and beaded processes. This study was designed to elucidate whether clasmatodendrosis may be one of the autophagy-related degeneration of astrocytes. In this study, clasmatodendritic astrocytes were observed only in the stratum radiatum in the CA1 region. Vacuoles in clasmatodendritic astrocytes showed LAMP-1 immunoreactivity. In addition, both LC3-II and Beclin-1 expression were detected in most of clasmatodendritic astrocytes as well as a few non-vacuolized astrocytes. Clasmatodendritic astrocytes also showed p65/RelA-Ser529 phosphorylation in the nuclei. The neutralization of TNF-α by sTNFp55R infusion reduced clasmatodendritic astrocytes with nuclear p65/RelA-Ser529 phosphorylation. Therefore, these findings suggest that clasmatodendrosis may be autophagic astroglial death in response to epileptic seizures through TNF-α-mediated p65/RelA-Ser529 phosphorylation.

Response of human natural killer cells to monocyte-derived dendritic cells infected with dengue virus (67.10)

Abstract Natural Killer (NK) cells are involved in innate responses triggered early during viral infections. However, the factors that regulate the response of primary human NK cells to primary human cells infected with dengue virus (DV) remain poorly characterized. In this study, we demonstrate that naïve NK cells co-cultured with DV-infected monocyte-derived dendritic cells (DCs) produce IFN-γ, upregulate cell surface CD107a, and lyse DV-infected DCs. Type I interferons and TNF-α produced by the DV-infected DCs were crucial for this IFN-γ response, since blocking IFNAR combined with neutralization of TNF-α completely abolished the IFN-γ response in these co-cultures. Cytokines previously reported to play important roles in NK cell activation, e.g. IL-12, IL-15, IL-18, IL-21, and IL-27, were not produced in significant amounts by DV-infected DCs. Transwell experiments suggested that membrane-bound ligands were also important for NK cell recognition of DV-infected DCs. However, we failed to detect the upregulation of ligands for NKG2D or DNAM-1 on DV-infected DCs. Ligands for the natural cytotoxicity receptors were determined not to contribute to the IFN-γ response. In summary, our results have uncovered a previously unappreciated role for the synergy between type I interferons and TNF-α in triggering the anti-dengue response of naïve human NK cells.

Anti-TNF-α Antibody (Infliximab) Therapy Supports the Recovery of eNOS and VEGFR2 Protein Expression in Endothelial Cells

The aim of this study is to investigate the effect of sera obtained from patients of Crohn's disease treated by anti-TNF-alpha antibody (Infliximab) on the expression of endothelial nitric oxide synthase (eNOS) and vascular endothelial growth factor receptor-2 (VEGFR2) protein in human umbilical vein endothelial cells (HUVEC) cultured in vitro. HUVEC was cultured in the presence of sera derived from patients before and after treatment, or from healthy individuals. Effects of sera on the expression of eNOS and VEGFR2 were monitored by determination of mRNA and protein levels using real time quantitative PCR and Western blot analysis, respectively. The serum of Crohn's patients contained elevated levels of TNF-alpha (34±1.80 pg/mL), which resulted in a decrease in the protein level of eNOS in HUVEC with a simultaneous induction of VEGFR2. Infliximab treatment normalized the expression level of these proteins by decreasing TNF-alpha level, particularly in those cases when clinical healing was also recorded, and it also conferred restitution of the level of angiogenic cytokines. Results suggest that altered angiogenesis possibly contributes to the initiation and perpetuation of inflammatory processes in inflammatory bowel disease (IBD). Endothelial dysfunction, a selective feature of Crohn's disease is beneficially affected by intravascular TNF-alpha neutralization.

Renal tubular fluid shear stress promotes endothelial cell activation

Modified urinary fluid shear stress (FSS) induced by variations of urinary fluid flow and composition is observed in early phases of most kidney diseases. In this study, we hypothesized that changes in urinary FSS represent a tubular aggression that contributes to the development of inflammation, a key event in progression of nephropathies. Human renal tubular cells (HK-2) were exposed to FSS for 30min at 0.01Pa. Treatment of human endothelial cells (HMEC-1) with the resulting conditioned medium (FSS-CM) increased C-C chemokine ligand 2 (CCL2) and tumor necrosis factor (TNF)-α protein secretion, increased endothelial vascular adhesion molecule-1 (VCAM-1) mRNA expression and stimulated adhesion of human (THP-1) monocytes to the endothelial monolayer. These effects were TNF-α dependent as they were abolished by neutralization of TNF-α. Interestingly, the origin of TNF-α was not epithelial, but resulted from autocrine endothelial production. However, in contrast to short term FSS, long term FSS (5h) induced the release of the key inflammatory proteins CCL2 and TNF-α directly from tubular cells. In conclusion, these results suggest for the first time that urinary FSS can contribute to the inflammatory state involved in initiation/perpetuation of renal diseases.

Blocking TNF-α by combination of TNF-α- and TNFR-binding cyclic peptide ameliorates the severity of TNBS-induced colitis in rats

Tumor necrosis factor alpha (TNF-α) has been implicated in the pathogenesis of Crohn's disease. TNF antagonists are effectively used to treat these patients, although the efficiency of different antagonists varies. In the present study we combined TNF-α binding cyclic peptide (TBCP) and TNFR1 binding cyclic peptide (TRBCP) to treat TNBS-induced colitis in rats for one week. The symptoms of colitis including bloody diarrhea, rectal prolapse, and a profound and sustained weight loss were significantly ameliorated and the colon inflammatory damage, both macroscopic and histological scores, MPO activity, and NO production were markedly decreased in rats by neutralization of TNF-α and blocking TNFR1, as compared with those in rats treated with irrelevant peptide or normal saline (P<0.05). The transcripts of IL-1β and IL-8, and the protein expression of TNF-α in rats treated with both TBCP and TRBCP were also down-regulated (P<0.05), while these proinflammatory cytokines remained unchanged in rats treated with irrelevant peptide or normal saline. These findings suggest that the combination of TNF-α- and TNFR1-binding peptide effectively improves the symptoms of TNBS-induced colitis and alleviates colonic pathological damages in rats. This combination may be a potent candidate for clinical treatment of the inflammatory bowel disease.

Humanization and Characterization of an Anti-Human TNF-α Murine Monoclonal Antibody

A murine monoclonal antibody, m357, showing the highly neutralizing activities for human tumor necrosis factor (TNF-α) was chosen to be humanized by a variable domain resurfacing approach. The non-conserved surface residues in the framework regions of both the heavy and light chain variable regions were identified via a molecular modeling of m357 built by computer-assisted homology modeling. By replacing these critical surface residues with the human counterparts, a humanized version, h357, was generated. The humanized h357 IgG1 was then stably expressed in a mammalian cell line and the purified antibody maintained the high antigen binding affinity as compared with the parental m357 based on a soluble TNF-α neutralization bioassay. Furthermore, h357 IgG1 possesses the ability to mediate antibody-dependent cell-mediated cytotoxicity and complement dependent cytotoxicity upon binding to cells bearing the transmembrane form of TNF-α. In a mouse model of collagen antibody-induced arthritis, h357 IgG significantly inhibited disease progression by intra-peritoneal injection of 50 µg/mouse once-daily for 9 consecutive days. These results provided a basis for the development of h357 IgG as therapeutic use.

Blockade of TNF-α rapidly inhibits pain responses in the central nervous system

There has been a consistent gap in understanding how TNF-α neutralization affects the disease state of arthritis patients so rapidly, considering that joint inflammation in rheumatoid arthritis is a chronic condition with structural changes. We thus hypothesized that neutralization of TNF-α acts through the CNS before directly affecting joint inflammation. Through use of functional MRI (fMRI), we demonstrate that within 24 h after neutralization of TNF-α, nociceptive CNS activity in the thalamus and somatosensoric cortex, but also the activation of the limbic system, is blocked. Brain areas showing blood-oxygen level-dependent signals, a validated method to assess neuronal activity elicited by pain, were significantly reduced as early as 24 h after an infusion of a monoclonal antibody to TNF-α. In contrast, clinical and laboratory markers of inflammation, such as joint swelling and acute phase reactants, were not affected by anti-TNF-α at these early time points. Moreover, arthritic mice overexpressing human TNF-α showed an altered pain behavior and a more intensive, widespread, and prolonged brain activity upon nociceptive stimuli compared with wild-type mice. Similar to humans, these changes, as well as the rewiring of CNS activity resulting in tight clustering in the thalamus, were rapidly reversed after neutralization of TNF-α. These results suggest that neutralization of TNF-α affects nociceptive brain activity in the context of arthritis, long before it achieves anti-inflammatory effects in the joints.

Translational Research Efforts in Biomarkers and Biology of Early Transplant-Related Complications

In the time since the first allogeneic hematopoietic stem cell transplantation (HSCT) was performed over 40 years ago, this life-saving procedure has been used increasingly for patients with hematologic, metabolic, and malignant diseases. Despite major advances in our understanding of the immunologic processes (both beneficial and injurious) that are associated with HSCT and improvements in supportive and critical care medicine, successful outcomes are still limited by several serious complications. As such, the establishment of effective therapeutic strategies for these complications will be crucial as increasing numbers of high-risk transplants are performed each year. The development of such approaches is fundamentally dependent upon a basic understanding of pathophysiologic mechanisms of disease and also on our ability to successfully translate these insights back to the bedside. This brief review will highlight breakthroughs in translational research endeavors that have paved the way for the development of novel strategies intended to change the standard of care and optimize outcomes for patients in whom allogeneic HSCT offers the only hope for a cure.

TNFR1 delivers pro‐survival signals that are required for limiting TNFR2‐dependent activation‐induced cell death (AICD) in CD8+ T cells

Members of the TNF and TNF receptor (TNFR) superfamily play important roles in the maintenance of homeostasis of the immune system. Furthermore, several members of the TNFR family participate in T-cell activation and sustaining T-cell responses. We have shown that TNFR2 regulates T-cell activation by lowering the activation threshold and providing costimulatory signaling. Furthermore, activated TNFR2(-/-) CD8(+) T cells are highly resistant to activation-induced cell death (AICD). Here, we showed that using anti-TNFR2 antibodies to block TNFR2 on activated WT CD8(+) T cells rendered them resistant to AICD. This resistance of activated TNFR2(-/-) CD8(+) T cells to AICD correlated with the accumulation of TNF receptor-associated factor 2 (TRAF2). Overexpression of TRAF2 by retroviral transfection and knockdown of TRAF2 by small interfering RNA also support this conclusion. Furthermore, neutralizing TNF-α reduced TRAF2 accumulation in activated TNFR2(-/-) CD8(+) T cells and increased their susceptibility to AICD. AICD-resistant TNFR2(-/-) CD8(+) T cells expressed elevated levels of phosphorylated IκBα and higher DNA-binding activity of the p65 NK-κB subunit and neutralization of TNF-α blocked this increase. Therefore, in activated TNFR2(-/-) CD8(+) T cells, TNFR1 functions as a survival receptor by utilizing high intracellular levels of TRAF2 to promote IκBα phosphorylation and NF-κB activation.

TNF-α and IL-1β mediate Japanese encephalitis virus-induced RANTES gene expression in astrocytes

Infection with Japanese encephalitis virus (JEV) causes neuroinfection and neuroinflammation characterized by profound neuronal destruction/dysfunction, concomitant microgliosis/astrogliosis, and production of various molecules that initiate the recruitment of immune cells to the sites of infection. Previously, we reported that glial cells expressed RANTES (regulated upon activation, normal T cell expressed and secreted) with chemotactic activity in response to JEV infection. In this study, we further demonstrated that JEV-infected microglia had an additional activity in regulating RANTES production. Both astrocytes and microglia responded to JEV infection by releasing RANTES through a process likely related to viral replication. Independent of infectious virus, supernatants of JEV-infected microglia, but not JEV-infected astrocytes, caused additional RANTES production from astrocytes. Antibody neutralization studies suggested the potential involvement of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) in mediating additional RANTES production. Treatment of astrocyte cultures with TNF-α and IL-1β caused activation of several signaling molecules and transcription factors crucial to RANTES gene expression, including reactive oxygen species, extracellular signal-regulated kinase, NF-κB, and NF-IL6, increased RANTES gene promoter activity, and provoked RANTES production. As with RANTES, neutralization of bioactive TNF-α and IL-1β caused an attenuation of chemotactic activity from supernatants of mixed glia containing astrocytes and microglia during the course of JEV infection. In conclusion, TNF-α and IL-1β produced by JEV-infected microglia might trigger another mechanism which induces a secondary wave of RANTES gene expression by activating astrocytes. The released RANTES from glial cells might play a role in the recruitment of immune cells during JEV infection.