CD40 and OX40 ligand are differentially regulated on asthmatic airway smooth muscle

T cell and airway smooth muscle interaction: a key driver of asthmatic airway inflammation and remodeling

Cross talk between T cells and airway smooth muscle (ASM) may play a role in modulating asthmatic airway inflammation and remodeling. Infiltrating T cells have been observed within the ASM bundles of asthmatics, and a wide range of direct and indirect interactions between T cells and ASM has been demonstrated using various in vitro and in vivo model systems. Contact-dependent mechanisms such as ligation and activation of cellular adhesion and costimulatory molecules, as well as the formation of lymphocyte-derived membrane conduits, facilitate the adhesion, bidirectional communication, and transfer of materials between T and ASM cells. T cell-derived cytokines, particularly of the Th1, Th2, and Th17 subsets, modulate the secretome, proliferation, and contractility of ASM cells. This review summarizes the mechanisms governing T cell-ASM cross talk in the context of asthma. Understanding the underlying mechanistic basis is important for directing future research and developing therapeutic interventions targeted toward this complex interaction.

CD4+ T cell-derived IFN-γ and LIGHT synergistically upregulate chemokine production from airway smooth muscle cells

Airway smooth muscle (ASM) remodeling in asthmatic airways may contribute to persistent airflow limitation and airway hyperresponsiveness. CD4+ T cells infiltrate the ASM layer where they may induce a proliferative and secretory ASM cell phenotype. We studied the interaction between activated CD4+ T cells and ASM cells in co-culture in vitro and investigated the effects of CD4+ T cells on chemokine production by ASM cells. CD4+ T cells induced marked upregulation of C-X-C motif chemokine ligands (CXCL) 9, 10, and 11 in ASM cells. Blockade of the IFN-γ receptor on ASM cells prevented this upregulation. Furthermore, T cell-derived IFN-γ and LIGHT (lymphotoxin, exhibits inducible expression and competes with HSV glycoprotein D for binding to herpesvirus entry mediator, a receptor expressed on T lymphocytes) synergize in a dose-dependent manner to coordinately enhance CXCL9, 10, and 11 expression. The synergistic property of LIGHT was mediated exclusively through the lymphotoxin-β receptor (LTBR), but not herpes virus entry mediator (HVEM). Disruption of LTBR signaling in ASM cells reduced CXCL9, 10, and 11 production and ASM cell-mediated CD4+ T cell chemotaxis. We conclude that the LIGHT-LTBR signaling axis acts together with IFN-γ to regulate chemokines that mediate lymphocyte infiltration in asthmatics.

OX40L Inhibition Suppresses KLH‐driven Immune Responses in Healthy Volunteers: A Randomized Controlled Trial Demonstrating Proof‐of‐Pharmacology for KY1005

The safety, tolerability, immunogenicity, and pharmacokinetic (PK) profile of an anti‐OX40L monoclonal antibody (KY1005, currently amlitelimab) were evaluated. Pharmacodynamic (PD) effects were explored using keyhole limpet hemocyanin (KLH) and tetanus toxoid (TT) immunizations. Sixty‐four healthy male subjects (26.5 ± 6.0 years) were randomized to single doses of 0.006, 0.018, or 0.05 mg/kg, or multiple doses of 0.15, 0.45, 1.35, 4, or 12 mg/kg KY1005, or placebo (6:2). Serum KY1005 concentrations were measured. Antibody responses upon KLH and TT immunizations and skin response upon intradermal KLH administration were performed. PD data were analyzed using repeated measures analysis of covariances (ANCOVAs) and post hoc exposure‐response modeling. No serious adverse events occurred and all adverse events were temporary and of mild or moderate severity. A nonlinear increase in mean serum KY1005 concentrations was observed (median time to maximum concentration (T_max) ~ 4 hours, geometric mean terminal half‐life (t½) ~ 24 days). Cutaneous blood perfusion (estimated difference (ED) −13.4 arbitrary unit (AU), 95% confidence interval (CI) −23.0 AU to −3.8 AU) and erythema quantified as average redness (ED −0.23 AU, 95% CI −0.35 AU to −0.11 AU) decreased after KY1005 treatment at doses of 0.45 mg/kg and above. Exposure‐response analysis displayed a statistically significant treatment effect on anti‐KLH antibody titers (IgG maximum effect (E_max) −0.58 AU, 95% CI −1.10 AU to −0.06 AU) and skin response (erythema E_max −0.20 AU, 95% CI −0.29 AU to −0.11 AU). Administration of KY1005 demonstrated an acceptable safety and tolerability profile and PK analyses displayed a nonlinear profile of KY1005. Despite the observed variability, skin challenge response after KY1005 treatment indicated pharmacological activity of KY1005. Therefore, KY1005 shows potential as a novel pharmacological treatment in immune‐mediated disorders.

Immune Checkpoints: Novel Therapeutic Targets to Attenuate Sepsis-Induced Immunosuppression

Sepsis is a leading cause of death in intensive care units and survivors develop prolonged immunosuppression and a high incidence of recurrent infections. No definitive therapy exists to treat sepsis and physicians rely on supportive care including antibiotics, intravenous fluids, and vasopressors. With the rising incidence of antibiotic resistant microbes, it is becoming increasingly critical to discover novel therapeutics. Sepsis-induced leukocyte dysfunction and immunosuppression is recognized as an important contributor towards increased morbidity and mortality. Pre-clinical and clinical studies show that specific cell surface inhibitory immune checkpoint receptors and ligands including PD-1, PD-L1, CTLA4, BTLA, TIM3, OX40, and 2B4 play important roles in the pathophysiology of sepsis by mediating a fine balance between host immune competency and immunosuppression. Pre-clinical studies targeting the inhibitory effects of these immune checkpoints have demonstrated reversal of leukocyte dysfunction and improved host resistance of infection. Measurement of immune checkpoint expression on peripheral blood leukocytes may serve as a means of stratifying patients to direct individualized therapy. This review focuses on advances in our understanding of the role of immune checkpoints in the host response to infections, and the potential clinical application of therapeutics targeting the inhibitory immune checkpoint pathways for the management of septic patients.

Effect of Blocking the OX40/OX40L Signaling Pathway by siRNA Interference on Animal Experimental Study of Allergic Rhinitis

BACKGROUND

The identification of new approaches and intervention targets for the treatment of AR is urgently needed. We aimed to investigate the effect of blocking the OX40/OX40L signaling pathway by small interfering RNA (siRNA) on ovalbumin (OVA)-induced AR in a mouse model.

METHODS

After establishment of the AR model, the mice were interfered by siRNA-OX40L (experimental group), siRNA-C (negative control group), or PBS (control group). Nose scratching, sneezing and nasal discharge were observed. OX40L mRNA and protein and the IL-5, TNF-α, regulatory T cell (Treg) -specific marker Foxp3, and eosinophil (EOS) levels were analyzed.

RESULTS

The numbers of nose scratching and sneezing were significantly lower in the siRNA-OX40L-treated group (p <0.05). After the intervention of siRNA-OX40L, OX40L mRNA and protein levels were significantly inhibited (p <0.05), but the Foxp3 level was significantly increased in the experimental group (p <0.05). The IL-5 and TNF-α levels were significantly lower in the experimental group (p <0.05), and the reduction was more evident for the Th2-type cytokine IL-5 than for the Th1-type cytokine TNF-α. Few or no EOSs were found in the nasal mucosal epithelium of the experimental group (p <0.05), whereas EOS infiltration was significant in the other two groups.

CONCLUSIONS

Blockage of the OX40/OX40L signaling pathway with siRNA-OX40L interference can inhibit allergic reactions and relieve allergic symptoms in AR mice. The underlying mechanism may be related to correcting Th2 immune deviation, inducing immune tolerance, and promoting Treg production.

The immunobiology of CD27 and OX40 and their potential as targets for cancer immunotherapy

In recent years, monoclonal antibodies (mAbs) able to reinvigorate antitumor T-cell immunity have heralded a paradigm shift in cancer treatment. The most high profile of these mAbs block the inhibitory checkpoint receptors PD-1 and CTLA-4 and have improved life expectancy for patients across a range of tumor types. However, it is becoming increasingly clear that failure of some patients to respond to checkpoint inhibition is attributable to inadequate T-cell priming. For full T-cell activation, 2 signals must be received, and ligands providing the second of these signals, termed costimulation, are often lacking in tumors. Members of the TNF receptor superfamily (TNFRSF) are key costimulators of T cells during infection, and there has been an increasing interest in harnessing these receptors to augment tumor immunity. We here review the immunobiology of 2 particularly promising TNFRSF target receptors, CD27 and OX40, and their respective ligands, CD70 and OX40L, focusing on their role within a tumor setting. We describe the influence of CD27 and OX40 on human T cells based on in vitro studies and on the phenotypes of several recently described individuals exhibiting natural deficiencies in CD27/CD70 and OX40. Finally, we review key literature describing progress in elucidating the efficacy and mode of action of OX40- and CD27-targeting mAbs in preclinical models and provide an overview of current clinical trials targeting these promising receptor/ligand pairings in cancer.

OX40, OX40L and Autoimmunity: a Comprehensive Review

The tumour necrosis factor receptor OX40 (CD134) is activated by its cognate ligand OX40L (CD134L, CD252) and functions as a T cell co-stimulatory molecule. OX40-OX40L interactions have been proposed as a potential therapeutic target for treating autoimmunity. OX40 is expressed on activated T cells, and in the mouse at rest on regulatory T cells (Treg). OX40L is found on antigen-presenting cells, activated T cells and others including lymphoid tissue inducer cells, some endothelia and mast cells. Expression of both molecules is increased after antigen presentation occurs and also in response to multiple other pro-inflammatory factors including CD28 ligation, CD40L ligation and interferon-gamma signaling. Their interactions promote T cell survival, promote an effector T cell phenotype, promote T cell memory, tend to reduce regulatory function, increase effector cytokine production and enhance cell mobility. In some circumstances, OX40 agonism may be associated with increased tolerance, although timing with respect to antigenic stimulus is important. Further, recent work has suggested that OX40L blockade may be more effective than OX40 blockade in reducing autoimmunity. This article reviews the expression of OX40 and OX40L in health, the effects of their interactions and insights from their under- or over-expression. We then review OX40 and OX40L expression in human autoimmune disease, identified associations of variations in their genes (TNFRSF4 and TNFSF4, respectively) with autoimmunity, and data from animal models of human diseases. A rationale for blocking OX40-OX40L interaction in human autoimmunity is then presented along with commentary on the one trial of OX40L blockade in human disease conducted to date. Finally, we discuss potential problems with clinical use of OX40-OX40L directed pharmacotherapy.

CD38 and airway hyper-responsiveness: studies on human airway smooth muscle cells and mouse models

Asthma is an inflammatory disease in which altered calcium regulation, contractility, and airway smooth muscle (ASM) proliferation contribute to airway hyper-responsiveness and airway wall remodeling. The enzymatic activity of CD38, a cell-surface protein expressed in human ASM cells, generates calcium mobilizing second messenger molecules such as cyclic ADP-ribose. CD38 expression in human ASM cells is augmented by cytokines (e.g., TNF-α) that requires the activation of MAP kinases and the transcription factors, NF-κB and AP-1, and is post-transcriptionally regulated by miR-140-3p and miR-708 by binding to 3' Untranslated Region of CD38 as well as by modulating the activation of signaling mechanisms involved in its regulation. Mice deficient in Cd38 exhibit reduced airway responsiveness to inhaled methacholine relative to the response in wild-type mice. Intranasal challenge of Cd38-deficient mice with TNF-α or IL-13, or the environmental fungus Alternaria alternata, causes significantly attenuated methacholine responsiveness compared with wild-type mice, with comparable airway inflammation. Reciprocal bone marrow transfer studies revealed partial restoration of airway hyper-responsiveness to inhaled methacholine in the Cd38-deficient mice. These studies provide evidence for CD38 involvement in the development of airway hyper-responsiveness; a hallmark feature of asthma. Future studies aimed at drug discovery and delivery targeting CD38 expression and (or) activity are warranted.

Airway smooth muscle in asthma: just a target for bronchodilation?

Airway smooth muscle (ASM) has long been recognized as the main cell type responsible for bronchial hyperresponsiveness. It has, thus, been considered as a target for bronchodilation. In asthma, however, there is a complex relationship between ASM and inflammatory cells, such as mast cells and T lymphocytes. Moreover, the increased ASM mass in asthmatic airways is one of the key features of airway remodeling. This article aims to review the main concepts about the 3 possible roles of ASM in asthma: (1) contractile tone, (2) inflammatory response, and (3) remodeling.

OX40 ligand fusion protein delivered simultaneously with the BCG vaccine provides superior protection against murine Mycobacterium tuberculosis infection

Mycobacterium tuberculosis infection claims approximately 2 million lives per year, and improved efficacy of the BCG vaccine remains a World Health Organization priority. Successful vaccination against M. tuberculosis requires the induction and maintenance of T cells. Targeting molecules that promote T-cell survival may therefore provide an alternative strategy to classic adjuvants. We show that the interaction between T-cell-expressed OX40 and OX40L on antigen-presenting cells is critical for effective immunity to BCG. However, because OX40L is lost rapidly from antigen-presenting cells following BCG vaccination, maintenance of OX40-expressing vaccine-activated T cells may not be optimal. Delivering an OX40L:Ig fusion protein simultaneously with BCG provided superior immunity to intravenous and aerosol M. tuberculosis challenge even 6 months after vaccination, an effect that depends on natural killer 1.1(+) cells. Attenuated vaccines may therefore lack sufficient innate stimulation to maintain vaccine-specific T cells, which can be replaced by reagents binding inducible T-cell costimulators.

Th1 cytokine-induced syndecan-4 shedding by airway smooth muscle cells is dependent on mitogen-activated protein kinases

In asthma, airway smooth muscle (ASM) chemokine secretion can induce mast cell recruitment into the airways. The functions of the mast cell chemoattractant CXCL10, and other chemokines, are regulated by binding to heparan sulphates such as syndecan-4. This study is the first demonstration that airway smooth muscle cells (ASMC) from people with and without asthma express and shed syndecan-4 under basal conditions. Syndecan-4 shedding was enhanced by stimulation for 24 h with the Th1 cytokines interleukin-1β (IL-1β) or tumor necrosis factor-α (TNF-α), but not interferon-γ (IFNγ), nor the Th2 cytokines IL-4 and IL-13. ASMC stimulation with IL-1β, TNF-α, and IFNγ (cytomix) induced the highest level of syndecan-4 shedding. Nonasthmatic and asthmatic ASM cell-associated syndecan-4 protein expression was also increased by TNF-α or cytomix at 4-8 h, with the highest levels detected in cytomix-stimulated asthmatic cells. Cell-associated syndecan-4 levels were decreased by 24 h, whereas shedding remained elevated at 24 h, consistent with newly synthesized syndecan-4 being shed. Inhibition of ASMC matrix metalloproteinase-2 did not prevent syndecan-4 shedding, whereas inhibition of ERK MAPK activation reduced shedding from cytomix-stimulated ASMC. Although ERK inhibition had no effect on syndecan-4 mRNA levels stimulated by cytomix, it did cause an increase in cell-associated syndecan-4 levels, consistent with the shedding being inhibited. In conclusion, ASMC produce and shed syndecan-4 and although this is increased by the Th1 cytokines, the MAPK ERK only regulates shedding. ASMC syndecan-4 production during Th1 inflammatory conditions may regulate chemokine activity and mast cell recruitment to the ASM in asthma.

The pivotal role of airway smooth muscle in asthma pathophysiology

Asthma is characterized by the association of airway hyperresponsiveness (AHR), inflammation, and remodelling. The aim of the present article is to review the pivotal role of airway smooth muscle (ASM) in the pathophysiology of asthma. ASM is the main effector of AHR. The mechanisms of AHR in asthma may involve a larger release of contractile mediators and/or a lower release of relaxant mediators, an improved ASM cell excitation/contraction coupling, and/or an alteration in the contraction/load coupling. Beyond its contractile function, ASM is also involved in bronchial inflammation and remodelling. Whereas ASM is a target of the inflammatory process, it can also display proinflammatory and immunomodulatory functions, through its synthetic properties and the expression of a wide range of cell surface molecules. ASM remodelling represents a key feature of asthmatic bronchial remodelling. ASM also plays a role in promoting complementary airway structural alterations, in particular by its synthetic function.

Differential induction of CD38 expression by TNF-{alpha} in asthmatic airway smooth muscle cells

The ADP-ribosyl cyclase activity of CD38, a membrane protein expressed in human airway smooth muscle (ASM) cells, generates cyclic ADP-ribose (cADPR), a Ca²(+)-mobilizing agent. cADPR-mediated Ca²(+) responses to agonists are augmented in human ASM cells by TNF-α. CD38-deficient mice fail to develop airway hyperresponsiveness following intranasal TNF-α or IL-13 challenge, suggesting a role in asthma. The role of CD38 in human asthma remains unknown. We hypothesized that CD38 expression will be elevated in ASM cells from asthmatic donors (ASMA cells). CD38 mRNA and ADP-ribosyl cyclase activity were measured in cells maintained in growth-arrested conditions and exposed to vehicle or TNF-α (10-40 ng/ml). TNF-α-induced induction of CD38 expression was greater in ASMA than in ASM cells from nonasthmatic donors (ASMNA). In four of the six donors, basal and TNF-α-induced ERK and p38 MAPK activation were higher in ASMA than ASMNA cells. JNK MAPK activation was lower in ASMA than ASMNA cells. Nuclear NF-κB (p50 subunit) and phosphorylated c-Jun were comparable in cells from both groups, although nuclear c-Fos (part of the AP-1 complex) levels were lower in ASMA than ASMNA cells. NF-κB or AP-1 binding to their consensus sequences was comparable in ASMNA and ASMA cells, as are the decay kinetics of CD38 mRNA. The findings suggest that the differential induction of CD38 by TNF-α in ASMA cells is due to increased transcriptional regulation involving ERK and p38 MAPK activation and is independent of changes in NF-κB or AP-1 activation. The findings suggest a potential role for CD38 in the pathophysiology of asthma.

Rhinovirus-induced exacerbations of asthma: How is the {beta}2-adrenoceptor implicated?

Rhinovirus (RV) infections are the major cause of asthma exacerbations in children and adults. Under normal circumstances, asthmatic airway obstruction improves spontaneously or characteristically briskly in response to inhaled beta(2)-adrenergic receptor (beta(2)AR) agonists. During virus-associated exacerbations, an impaired response to beta(2)AR agonists is observed; the reason for this is not known. The objective of this study was to determine the effect of RV infection on airway smooth muscle beta(2)AR function. The human cell line Beas-2B and primary human bronchial epithelial cells (HBECs) were infected with RV (multiplicity of infection = 1). After 1 or 5 days for primary and Beas-2B cells, respectively, cell culture supernatants were harvested, UV-irradiated to inactivate RV, and applied to human airway smooth muscle cells for 3 days to assess modifications of beta(2)AR function. RV conditioned medium from Beas-2B and HBECs decreased beta(2)AR agonist-induced cAMP by 50 and 65%, respectively (n = 5; P < 0.05). When cAMP was induced independently of the beta(2)AR using forskolin, no impairment was found. Using flow cytometry, we demonstrated that this decrease was likely the result of beta(2)AR desensitization because membrane but not total cell receptor beta(2)AR was decreased. Pretreatment of HBECs and Beas-2B cells but not human airway smooth muscle cells with the corticosteroids dexamethasone or fluticasone abolished virus-mediated beta(2)AR loss of function. This study shows that epithelial infection with RV induces a decrease of beta(2)AR function on airway smooth muscle cells, potentially explaining the clinical observation of loss of beta(2)AR agonist function during RV-induced asthma exacerbations.