Modulation of the IL-33/IL-13 Axis in Obesity by IL-13Rα2.

In obesity, IL-13 overcomes insulin resistance by promoting anti-inflammatory macrophage differentiation in adipose tissue. Endogenous IL-13 levels can be modulated by the IL-13 decoy receptor, IL-13Rα2, which inactivates and depletes the cytokine. In this study, we show that IL-13Rα2 is markedly elevated in adipose tissues of obese mice. Mice deficient in IL-13Rα2 had high expression of IL-13 response markers in adipose tissue, consistent with increased IL-13 activity at baseline. Moreover, exposure to the type 2 cytokine-inducing alarmin, IL-33, enhanced serum and tissue IL-13 concentrations and elevated tissue eosinophils, macrophages, and type 2 innate lymphoid cells. IL-33 also reduced body weight, fat mass, and fasting blood glucose levels. Strikingly, however, the IL-33-induced protection was greater in IL-13Rα2-deficient mice compared with wild-type littermates, and these changes were largely attenuated in mice lacking IL-13. Although IL-33 administration improved the metabolic profile in the context of a high fat diet, it also resulted in diarrhea and perianal irritation, which was enhanced in the IL-13Rα2-deficient mice. Weight loss in this group was associated with reduced food intake, which was likely related to the gastrointestinal effects. These findings outline both potentially advantageous and deleterious effects of a type 2-skewed immune response under conditions of metabolic stress, and identify IL-13Rα2 as a critical checkpoint in adipose tissues that limits the protective effects of the IL-33/IL-13 axis in obesity.

Therapeutic activity of an interleukin-4/interleukin-13 dual antagonist on oxazolone-induced colitis in mice.

Interleukin-4 (IL-4) and IL-13 are critical drivers of immune activation and inflammation in ulcerative colitis, asthma and other diseases. Because these cytokines may have redundant function, dual targeting holds promise for achieving greater efficacy. We have recently described a bifunctional therapeutic targeting IL-4 and IL-13 developed on a novel protein scaffold, generated by combining specific binding domains in an optimal configuration using appropriate linker regions. In the current study, the bifunctional IL-4/IL-13 antagonist was evaluated in the murine oxazolone-induced colitis model, which produces disease with features of ulcerative colitis. The bifunctional IL-4/IL-13 antagonist reduced body weight loss throughout the 7-day course of the model, and ameliorated the increased colon weight and decreased colon length that accompany disease. Colon tissue gene expression was modulated in accordance with the treatment effect. Concentrations of serum amyloid P were elevated in proportion to disease severity, making it an effective biomarker. Serum concentrations of the bifunctional IL-4/IL-13 antagonist were inversely proportional to disease severity, colon tissue expression of pro-inflammatory genes, and serum amyloid P concentration. Taken together, these results define a panel of biomarkers signifying engagement of the IL-4/IL-13 pathway, confirm the T helper type 2 nature of disease in this model, and demonstrate the effectiveness of dual cytokine blockade.

An IL-4/IL-13 dual antagonist reduces lung inflammation, airway hyperresponsiveness, and IgE production in mice.

IL-4 and IL-13 comprise promising targets for therapeutic interventions in asthma and other Th2-associated diseases, but agents targeting either IL-4 or IL-13 alone have shown limited efficacy in human clinical studies. Because these cytokines may involve redundant function, dual targeting holds promise for achieving greater efficacy. We describe a bifunctional therapeutic targeting IL-4 and IL-13, developed by a combination of specific binding domains. IL-4-targeted and IL-13-targeted single chain variable fragments were joined in an optimal configuration, using appropriate linker regions on a novel protein scaffold. The bifunctional IL-4/IL-13 antagonist displayed high affinity for both cytokines. It was a potent and efficient neutralizer of both murine IL-4 and murine IL-13 bioactivity in cytokine-responsive Ba/F3 cells, and exhibited a half-life of approximately 4.7 days in mice. In a murine model of ovalbumin-induced ear swelling, the bifunctional molecule blocked both the IL-4/IL-13-dependent early-phase response and the IL-4-dependent late-phase response. In the ovalbumin-induced lung inflammation model, the bifunctional IL-4/IL-13 antagonist reduced the IL-4-dependent rise in serum IgE titers, and reduced IL-13-dependent airway hyperresponsiveness, lung inflammation, mucin gene expression, and serum chitinase responses. Taken together, these findings demonstrate the effective dual blockade of IL-4 and IL-13 with a single agent, which resulted in the modulation of a more extensive range of endpoints than could be achieved by targeting either cytokine alone.

Discovery of a Series of Pyrimidine Carboxamides as Inhibitors of Vanin-1.

A diaryl ketone series was identified as vanin-1 inhibitors from a high-throughput screening campaign. While this novel scaffold provided valuable probe 2 that was used to build target confidence, concerns over the ketone moiety led to the replacement of this group. The successful replacement of this moiety was achieved with pyrimidine carboxamides derived from cyclic secondary amines that were extensively characterized using biophysical and crystallographic methods as competitive inhibitors of vanin-1. Through optimization of potency and physicochemical and ADME properties, and guided by co-crystal structures with vanin-1, 3 was identified with a suitable profile for advancement into preclinical development.

Mast cell-dependent contraction of human airway smooth muscle cell-containing collagen gels: influence of cytokines, matrix metalloproteases, and serine proteases.

In asthma, mast cells infiltrate the airway smooth muscle cell layer and secrete proinflammatory and profibrotic agents that contribute to airway remodeling. To study the effects of mast cell activation on smooth muscle cell-dependent matrix contraction, we developed coculture systems of human airway smooth muscle cells (HASM) with primary human mast cells derived from circulating progenitors or with the HMC-1 human mast cell line. Activation of primary human mast cells by IgE receptor cross-linking or activation of HMC-1 cells with C5a stimulated contraction of HASM-embedded collagen gels. Contractile activity could be transferred with conditioned medium from activated mast cells, implicating involvement of soluble factors. Cytokines and proteases are among the agents released by activated mast cells that may promote a contractile response. Both IL-13 and IL-6 enhanced contraction in this model and the activity of IL-13 was ablated under conditions leading to expression of the inhibitory receptor IL-13Ralpha2 on HASM. In addition to cytokines, matrix metalloproteinases (MMPs), and serine proteases induced matrix contraction. Inhibitor studies suggested that, although IL-13 could contribute to contraction driven by mast cell activation, MMPs were critical mediators of the response. Both MMP-1 and MMP-2 were strongly expressed in this system. Serine proteases also contributed to contraction induced by mast cell-activating agents and IL-13, most likely by mediating the proteolytic activation of MMPs. Hypercontractility is a hallmark of smooth muscle cells in the asthmatic lung. Our findings define novel mechanisms whereby mast cells may modulate HASM-driven contractile responses.

Optimization of 5-vinylaryl-3-pyridinecarbonitriles as PKCtheta inhibitors.

Analog 8, a 3-pyridinecarbonitrile with an (E)-2-[6-[(4-methylpiperazin-1-yl)methyl]pyridin-2-yl]vinyl group at C-5, had an IC(50) value of 1.1 nM for the inhibition of PKCtheta and potently blocked the production of IL-2 in both stimulated murine T cells (IC(50)=34 nM) and human whole blood (IC(50)=500 nM).

C-5 Substituted heteroaryl 3-pyridinecarbonitriles as PKCtheta inhibitors: Part I.

We earlier reported that 3-pyridinecarbonitriiles with a 4-methylindolyl-5-amino group at C-4 and a phenyl group at C-5 were inhibitors of PKCtheta. Keeping the group at C-4 of the pyridine core constant, we varied the water solubilizing group on the phenyl ring at C-5 and then replaced the C-5 phenyl ring with several monocyclic heteroaryl rings, including furan, thiophene and pyridine. Analog 6e with a 4-methylindol-5-ylamino group at C-4 and a 5-[(4-methylpiperazin-1-yl)methyl]-2-furyl group C-5 had an IC50 value of 4.5 nM for the inhibition of PKCtheta.

Synthesis and PKCtheta inhibitory activity of a series of 4-indolylamino-5-phenyl-3-pyridinecarbonitriles.

A series of 4-indolylamino-5-phenyl-3-pyridinecarbonitrile inhibitors of PKCtheta were synthesized as potential anti-inflammatory agents. The effects of specific substitution on the 5-phenyl moiety and variations of the positional isomers of the 4-indolylamino substituent were explored. This study led to the discovery of compound 12d, which had an IC(50) value of 18nM for the inhibition of PKCtheta.

Optimization of 5-phenyl-3-pyridinecarbonitriles as PKCtheta inhibitors.

The key intermediate, 4-chloro-5-iodo-3-pyridinecarbonitrile, allowed for ready optimization of the PKCtheta inhibitory activity of a series of 3-pyridinecarbonitriles. Analog 13b with a 4-methylindol-5-ylamino group at C-4 and a 4-(2-(4-methylpiperazin-1-yl)ethoxy)phenyl group at C-5 had an IC(50) value of 7.4nM for the inhibition of PKCtheta.

First generation 5-vinyl-3-pyridinecarbonitrile PKCtheta inhibitors.

A series of 5-vinyl-3-pyridinecarbonitriles were synthesized and evaluated as PKCtheta inhibitors. The systematic optimization of 4-[(4-methyl-1H-indol-5-yl)amino]-5-[(E)-2-phenylvinyl]-3-pyridinecarbonitrile 3 resulted in the identification of compound 23e as a potent PKCtheta inhibitor with good selectivity over PKCdelta.

C-5 substituted heteroaryl-3-pyridinecarbonitriles as PKCtheta inhibitors: part II.

We previously reported that a 3-pyridinecarbonitrile analog with a furan substituent at C-5 and a 4-methylindol-5-ylamino substituent at C-4, 1, was a potent inhibitor of PKCtheta (IC50=4.5 nM). Replacement of the C-5 furan ring of 1 with bicyclic heteroaryl rings, led to compounds with significantly improved potency against PKCtheta. Analog 6b with a 4-methylindol-5-ylamino group at C-4 and a 5-[(4-methylpiperazin-1-yl)methyl]-1-benzofuran-2-yl group at C-5 had an IC50 value of 0.28 nM for the inhibition of PKCtheta.

5-Vinyl-3-pyridinecarbonitrile inhibitors of PKCtheta: optimization of enzymatic and functional activity.

PKCtheta is a serine/threonine kinase involved in the regulation of IL2 production in T cells. It has recently become an attractive therapeutic target for a variety of immunological disorders. We describe the optimization of the enzymatic and cellular potency of a series of 5-vinyl-3-pyridinecarbonitrile inhibitors of PKCtheta. A binding model was developed that explains much of the SAR observed for this series, including the enzymatic potency observed for 19. An analysis of functional potency against various physiochemical parameters suggests that cellular potency is correlated with LogD(7.4), but not with cLogP, PAMPA permeability, or TPSA.

Identification, characterization and initial hit-to-lead optimization of a series of 4-arylamino-3-pyridinecarbonitrile as protein kinase C theta (PKCtheta) inhibitors.

The protein kinase C (PKC) family of serine/threonine kinases is implicated in a wide variety of cellular processes. The PKC theta (PKCtheta) isoform is involved in TCR signal transduction and T cell activation and regulates T cell mediated diseases, including lung inflammation and airway hyperresponsiveness. Thus inhibition of PKCtheta enzyme activity by a small molecule represents an attractive strategy for the treatment of asthma. A PKCtheta high-throughput screening (HTS) campaign led to the identification of 4-(3-bromophenylamino)-5-(3,4-dimethoxyphenyl)-3-pyridinecarbonitrile 4a, a low microM ATP competitive PKCtheta inhibitor. Structure based hit-to-lead optimization led to the identification of 5-(3,4-dimethoxyphenyl)-4-(1H-indol-5-ylamino)-3-pyridinecarbonitrile 4p, a 70 nM PKCtheta inhibitor. Compound 4p was selective for inhibition of novel PKC isoforms over a panel of 21 serine/threonine, tyrosine, and phosphoinositol kinases, in addition to the conventional and atypical PKCs, PKCbeta, and PKCzeta, respectively. Compound 4p also inhibited IL-2 production in antiCD3/anti-CD28 activated T cells enriched from splenocytes.