Targeting MAP3K19 prevents human lung myofibroblast activation both in vitro and in a humanized SCID model of idiopathic pulmonary fibrosis.

Idiopathic Pulmonary Fibrosis (IPF) is a disease with a devastating prognosis characterized by unrelenting lung scarring. Aberrant activation of lung fibroblasts is a key feature of this disease, yet the key pathways responsible for this are poorly understood. Mitogen-activated protein kinase, kinase, kinase- 19 (MAP3K19) was recently shown to be upregulated in IPF and this MAPK has a key role in target gene transcription in the TGF-ß pathway. Herein, we further investigate the role of MAP3K19 in cultured normal and IPF fibroblasts and in a humanized SCID mouse model of IPF employing both short interfering (si) RNA and novel small-molecule inhibitors directed at this kinase. Targeting MAP3K19 had significant inhibitory effects on the expression of both alpha smooth muscle actin and extracellular matrix in cultured human IPF fibroblasts. Quantitative protein and biochemical assays, as well as histological analysis, showed that MAP3K19 was required for the development of lung fibrosis in SCID mice humanized with IPF lung fibroblasts. MAP3K19 was required for IPF myofibroblast differentiation, and targeting its activity attenuated the profibrotic activity of these cells both in vitro and in an adoptive transfer SCID model of pulmonary fibrosis.

MAP3K19 Is Overexpressed in COPD and Is a Central Mediator of Cigarette Smoke-Induced Pulmonary Inflammation and Lower Airway Destruction.

Chronic obstructive pulmonary disease (COPD) is characterized by persistent airflow limitation and lung inflammation resulting in a progressive decline in lung function whose principle cause is cigarette smoke. MAP3K19 is a novel kinase expressed predominantly by alveolar and interstitial macrophages and bronchial epithelial cells in the lung. We found that MAP3K19 mRNA was overexpressed in a limited sampling of lung tissue from COPD patients, and a closer examination found it to be overexpressed in bronchoalveolar macrophages from COPD patients, as well as the bronchial epithelium and inflammatory cells in the lamina propria. We further found MAP3K19 to be induced in various cell lines upon environmental stress, such as cigarette smoke, oxidative and osmotic stress. Exogenous expression of MAP3K19 in cells caused an upregulation of transcriptionally active NF-κB, and secretion of the chemokines CXCL-8, CCL-20 and CCL-7. Inhibition of MAP3K19 activity by siRNA or small molecular weight inhibitors caused a decrease in cigarette smoke-induced inflammation in various murine models, which included a decrease in pulmonary neutrophilia and KC levels. In a chronic cigarette smoke model, inhibition of MAP3K19 significantly attenuated emphysematous changes in airway parenchyma. Finally, in a viral exacerbation model, mice exposed to cigarette smoke and influenza A virus showed a decrease in pulmonary neutrophilia, pro-inflammatory cytokines and viral load upon inhibition of MAP3K19. Collectively, these results suggest that inhibition of MAP3K19 may represent a novel strategy to target COPD that promises to have a potential therapeutic benefit for patients.

MAP3K19 Is a Novel Regulator of TGF-ß Signaling That Impacts Bleomycin-Induced Lung Injury and Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a progressive, debilitating disease for which two medications, pirfenidone and nintedanib, have only recently been approved for treatment. The cytokine TGF-ß has been shown to be a central mediator in the disease process. We investigated the role of a novel kinase, MAP3K19, upregulated in IPF tissue, in TGF-ß-induced signal transduction and in bleomycin-induced pulmonary fibrosis. MAP3K19 has a very limited tissue expression, restricted primarily to the lungs and trachea. In pulmonary tissue, expression was predominantly localized to alveolar and interstitial macrophages, bronchial epithelial cells and type II pneumocytes of the epithelium. MAP3K19 was also found to be overexpressed in bronchoalveolar lavage macrophages from IPF patients compared to normal patients. Treatment of A549 or THP-1 cells with either MAP3K19 siRNA or a highly potent and specific inhibitor reduced phospho-Smad2 & 3 nuclear translocation following TGF-ß stimulation. TGF-ß-induced gene transcription was also strongly inhibited by both the MAP3K19 inhibitor and nintedanib, whereas pirfenidone had a much less pronounced effect. In combination, the MAP3K19 inhibitor appeared to act synergistically with either pirfenidone or nintedanib, at the level of target gene transcription or protein production. Finally, in an animal model of IPF, inhibition of MAP3K19 strongly attenuated bleomycin-induced pulmonary fibrosis when administered either prophylactically ortherapeutically. In summary, these results strongly suggest that inhibition of MAP3K19 may have a beneficial therapeutic effect in the treatment of IPF and represents a novel strategy to target this disease.

Murine bone marrow-derived mast cells express chemoattractant receptor-homologous molecule expressed on T-helper class 2 cells (CRTh2).

Mast cells are bone marrow-derived effector cells that can initiate inflammatory responses to infectious organisms or allergens by releasing a multitude of pro-inflammatory factors including prostaglandin (PG) D(2). We demonstrate that primary murine bone marrow-derived mast cells (BMMCs) express the PGD(2) receptor; chemoattractant receptor-homologous molecule expressed on T(h) class 2 cells (CRT(h)2). Activation of CRT(h)2 on BMMC by PGD(2) or the CRT(h)2-specific agonist, 13,14-dihydro-15-keto-prostaglandin D(2) (DK-PGD(2)), resulted in signaling response including Ca(2+) mobilization and phosphorylation of the p42/p44 extracellular signal-regulated kinases (ERKs) kinases. Phosphorylation of the ERKs could be blocked by pertussis toxin, as well as a small molecule antagonist of CRT(h)2, Compound A. Activation of CRT(h)2 on BMMC also resulted in the up-regulation of CD23 and CD30 on the cell surface, as well as CD62L shedding. Finally, PGD(2) and DK-PGD(2) induced the migration of BMMC in vitro and in vivo in response to an intra-dermal DK-PGD(2) injection. Both these processes were inhibited by the CRT(h)2 antagonist. These results raise the possibility that the functional consequences of the PGD(2)-CRT(h)2 interaction on mast cells may be relevant in allergic inflammation.

A small molecule CRTH2 antagonist inhibits FITC-induced allergic cutaneous inflammation.

A FITC-induced allergic contact hypersensitivity model was used to investigate the role that the prostaglandin D(2) receptor-chemoattractant receptor-homologous molecule expressed on T(h)2 cells (CRTH2) plays in modulating cutaneous inflammation. Our results show that inhibition of CRTH2, achieved via administration of a potent, small molecule antagonist, Compound A (Cmpd A), effectively blocked edema formation and greatly reduced the inflammatory infiltrate and skin pathology observed in drug vehicle-treated animals. Gene expression analysis revealed that Cmpd A administration down-regulated the transcription of a wide range of pro-inflammatory mediators. This correlated with decreases in cytokine and chemokine protein levels, notably IL-4, IL-1beta, tumor necrosis factor-alpha, transforming growth factor-beta, GRO-alpha, MIP-2 and thymic stromal lymphopoietin (TSLP) in FITC-challenged ears. The administration of an anti-TSLP-neutralizing antibody was only partially effective in lowering the FITC-induced inflammatory infiltrate and cytokine production compared with the CRTH2 antagonist. Taken together, these data suggest that blockade of CRTH2 inhibits multiple pathways leading to cutaneous inflammation in this model. This suggests that CRTH2 antagonism may be a viable route for therapeutic intervention in allergic skin diseases, such as atopic dermatitis.

Antagonism of CRTH2 ameliorates chronic epicutaneous sensitization-induced inflammation by multiple mechanisms.

Prostaglandin D(2) (PGD(2)) and its receptor chemoattractant receptor homologous molecule expressed on T(h)2 cells (CRTH2) have been implicated in the pathogenesis of numerous allergic diseases. We investigated the role of PGD(2) and CRTH2 in allergic cutaneous inflammation by using a highly potent and specific antagonist of CRTH2. Administration of this antagonist ameliorated cutaneous inflammation caused by either repeated epicutaneous ovalbumin or FITC sensitization. Gene expression and ELISA analysis revealed that there was reduced pro-inflammatory cytokine mRNA or protein produced. Importantly, the CRTH2 antagonist reduced total IgE, as well as antigen-specific IgE, IgG1 and IgG2a antibody levels. This reduction in antibody production correlated to reduced cytokines produced by splenocytes following in vitro antigen challenge. An examination of skin CD11c(+) dendritic cells (DC) showed that in mice treated with the CRTH2 antagonist, there was a decrease in the number of these cells that migrated to the draining lymph nodes in response to FITC application to the skin. Additionally, naive CD4(+) T lymphocytes co-cultured with skin-derived DC from CRTH2 antagonist-treated mice showed a reduced ability to produce a number of cytokines compared with DC from vehicle-treated mice. Collectively, these findings suggest that CRTH2 has a pivotal role in mediating the inflammation and the underlying immune response following epicutaneous sensitization.

CRTH2 antagonism significantly ameliorates airway hyperreactivity and downregulates inflammation-induced genes in a mouse model of airway inflammation.

Prostaglandin D(2), the ligand for the G protein-coupled receptors DP1 and CRTH2, has been implicated in the pathogenesis of the allergic response in diseases such as asthma, rhinitis, and atopic dermatitis. This prostanoid also fulfills a number of physiological, anti-inflammatory roles through its receptor DP1. We investigated the role of PGD(2) and CRTH2 in allergic pulmonary inflammation by using a highly potent and specific antagonist of CRTH2. Administration of this antagonist ameliorated inflammation caused by either acute or subchronic sensitization using the cockroach egg antigen. Gene expression and ELISA analysis revealed that there was reduced proinflammatory cytokine mRNA or protein produced, as well as a wide array of genes associated with the Th2-type proinflammatory response. Importantly, the CRTH2 antagonist reduced antigen-specific IgE, IgG1, and IgG2a antibody levels as well as decreased mucus deposition and leukocyte infiltration in the large airways. Collectively, these findings suggest that the PGD(2)-CRTH2 activation axis has a pivotal role in mediating the inflammation and the underlying immune response in a T cell-driven model of allergic airway inflammation.

Cutting edge: serotonin is a chemotactic factor for eosinophils and functions additively with eotaxin.

Elevated levels of serotonin (5-hydroxytryptamine, 5-HT) are observed in the serum of asthmatics. Herein, we demonstrate that 5-HT functions independently as an eosinophil chemoattractant that acts additively with eotaxin. 5-HT2A receptor antagonists (including MDL-100907 and cyproheptadine (CYP)) were found to inhibit 5-HT-induced, but not eotaxin-induced migration. Intravital microscopy studies revealed that eosinophils roll in response to 5-HT in venules under conditions of physiological shear stress, which could be blocked by pretreating eosinophils with CYP. OVA-induced pulmonary eosinophilia in wild-type mice was significantly inhibited using CYP alone and maximally in combination with a CCR3 receptor antagonist. Interestingly, OVA-induced pulmonary eosinophilia in eotaxin-knockout (Eot-/-) mice was inhibited by treatment with the 5-HT2A but not CCR3 receptor antagonist. These results suggest that 5-HT is a potent eosinophil-active chemoattractant that can function additively with eotaxin and a dual CCR3/5-HT2A receptor antagonist may be more effective in blocking allergen-induced eosinophil recruitment.

Chemokine receptor binding and signal transduction in native cells of the central nervous system.

Chemokine receptors belong to the superfamily of seven-transmembrane-spanning, G-protein-coupled receptors, and their expression by central nervous system cells is clearly documented. As this gene family has become the target of novel therapeutic development, the analysis of these receptors requires radioligand binding techniques as well as methods that entail assessing receptor stimulation of signal transduction pathways. Herein, we describe specific protocols for measuring radiolabeled chemokine binding to their cognate receptors on cultured glial cells as well as to receptors expressed in heterologous cell systems. Multiple downstream signaling pathways, including intracellular calcium influx and receptor-dependent kinase activation, are associated with chemokine receptor stimulation. Protocols for measuring these signaling events in chemokine-receptor-expressing cells are also presented.

Immunological characterization and therapeutic activity of an altered-peptide ligand, NBI-6024, based on the immunodominant type 1 diabetes autoantigen insulin B-chain (9-23) peptide.

The nonobese diabetic (NOD) mouse is a good model for human type 1 diabetes, which is characterized by autoreactive T-cell-mediated destruction of insulin-producing islet beta-cells of the pancreas. The 9-23 amino acid region of the insulin B-chain [B((9-23))] is an immunodominant T-cell target antigen in the NOD mouse that plays a critical role in the disease process. By testing a series of B((9-23)) peptide analogs with single or double alanine substitutions, we identified a set of altered peptide ligands (APLs) capable of inhibiting B((9-23))-induced proliferative responses of NOD pathogenic T-cell clones. These APLs were unable to induce proliferation of these clones. However, vaccinations with the APLs induced strong cellular responses, as measured by in vitro lymphocyte proliferation and Th2 cytokine production (i.e., interleukin [IL]-4 and IL-10, but not gamma-interferon [IFN-gamma]). These responses were cross-reactive with the native antigen, B((9-23)), suggesting that the APL-induced Th2 responses may provide protection by controlling endogenous B((9-23))-specific Th1 (i.e., IFN-gamma-producing) pathogenic responses. One of these APLs that contained alanine substitutions at residues 16 and 19 (16Y-->A, 19C-->A; NBI-6024) was further characterized for its therapeutic activity because it consistently induced T-cell responses (e.g., T-cell lines and clones) that were of the Th2 type and that were cross-reactive with B((9-23)). Subcutaneous injections of NBI-6024 to NOD mice administered either before or after the onset of disease substantially delayed the onset and reduced the incidence of diabetes. This study is the first to report therapeutic activity of an APL derived from an islet beta-cell-specific antigen in type 1 diabetes.

Regulation of murine macrophage proinflammatory and anti-inflammatory cytokines by ligands for peroxisome proliferator-activated receptor-gamma: counter-regulatory activity by IFN-gamma.

The prostaglandin, 15-deoxy Delta(12,14)-prostaglandin J2 (15d-PGJ2)(1), and thiazolidinediones are ligands for the nuclear receptor, peroxisome proliferator-activated receptor (PPAR)-gamma, which mediates anti-inflammatory activity by suppressing murine macrophage (Mphi) production of the inflammatory mediator, nitric oxide (NO). Here, we elucidated this anti-inflammatory activity further by investigating whether PPAR-gamma ligands regulated a panel of proinflammatory and anti-inflammatory cytokines produced by primary inflammatory murine Mphi (thioglycollate-elicited peritoneal exudate Mphi; PEM). Thiazolidinediones and 15d-PGJ2 suppressed lipopolysaccharide (LPS)-induced PEM production of NO and IL-12(p40) to a greater extent than IL-6 and TNF-alpha production. Whereas 15d-PGJ2 showed the greatest extent of suppression of proinflammatory mediator production, the thiazolidinedione, BRL49653, was the most potent compound studied. Surprisingly, treatment with the Mphi-activation cytokine, IFN-gamma, prevented PPAR-gamma ligands from suppressing the proinflammatory cytokines completely and reduced their suppression of NO production substantially, demonstrating that activation conditions affect PPAR-gamma-mediated, anti-inflammatory activity. Western analysis demonstrated that the antagonistic activity of IFN-gamma did not involve modulation of PPAR-gamma expression but showed that IFN-gamma interfered with PPAR-gamma ligand regulation of p42/p44 MAP kinase activation and the cytosolic disappearance of NF-kappaB upon LPS stimulation. Finally, we showed that PPAR-gamma ligands did not substantially modulate production of the anti-inflammatory cytokine, IL-10, and that antibody-mediated neutralization of IL-10 did not prevent the ligands from suppressing proinflammatory mediator production. In contrast to studies with noninflammatory human monocytes and Mphi, our results demonstrate that primary murine inflammatory Mphi are extremely sensitive to the anti-inflammatory activity of PPAR-gamma ligands. These results suggest that drugs such as thiazolidinediones may be most effective in suppressing Mphi activity early (i.e., in the absence of lymphocyte-derived IFN-gamma) in the inflammatory process.