A selective p38 alpha mitogen-activated protein kinase inhibitor reverses cartilage and bone destruction in mice with collagen-induced arthritis

Destruction of cartilage and bone is a poorly managed hallmark of human rheumatoid arthritis (RA). p38 Mitogen-activated protein kinase (MAPK) has been shown to regulate key proinflammatory pathways in RA, including tumor necrosis factor alpha, interleukin (IL)-1beta, and cyclooxygenase-2, as well as the process of osteoclast differentiation. Therefore, we evaluated whether a p38alpha MAPK inhibitor, indole-5-carboxamide (SD-282), could modulate cartilage and bone destruction in a mouse model of RA induced with bovine type II collagen [collagen-induced arthritis (CIA)]. In mice with early disease, SD-282 treatment significantly improved clinical severity scores, reduced bone and cartilage loss, and reduced mRNA levels of proinflammatory genes in paw tissue, including IL-1beta, IL-6, and cyclooxygenase-2. Notably, SD-282 treatment of mice with advanced disease resulted in significant improvement in clinical severity scoring and paw swelling, a reversal in bone and cartilage destruction as assessed by histology, bone volume fraction and thickness, and three-dimensional image analysis. These changes were accompanied by reduced osteoclast number and lowered levels of serum cartilage oligomeric matrix protein, a marker of cartilage breakdown. Thus, in a model of experimental arthritis associated with significant osteolysis, p38alpha MAPK inhibition not only attenuates disease progression but also reverses cartilage and bone destruction in mice with advanced CIA disease.     

FR167653, a p38 mitogen-activated protein kinase inhibitor, prevents Helicobacter pylori-induced gastritis in Mongolian gerbils

FR167653 was discovered as a cytokine production inhibitor, but its target molecule has remained unclear. We examined the effect of FR167653 on activities of purified protein kinases. FR167653 dose dependently inhibited p38alpha mitogen-activated protein kinase activity without affecting the activities of other kinases. FR167653 had no effect on cyclooxygenase (COX)-1 or COX-2 activities, whereas SB203580 inhibited them. FR167653 suppressed endogenous p38 kinase activity in interleukin-1-stimulated NRK-F cells. These results indicate that FR167653 is a p38 kinase-selective inhibitor without affecting COX activity. To evaluate the role of p38 kinase in Helicobacter pylori gastritis, we therefore examined the effect of FR167653 on H. pylori-induced gastritis in Mongolian gerbils. H. pylori infection activated p38 kinase in the gastric mucosa and caused neutrophil infiltration from 2 and 3 weeks of infection, respectively. At 4 weeks, severe mucosal inflammation with erosive injury was observed. When FR167653 was administered to H. pylori-infected gerbils from 2 weeks, both neutrophil infiltration and mucosal injury at 4 weeks were significantly prevented. FR167653 markedly reduced the H. pylori-induced increase in endogenous p38 kinase activity in the gastric mucosa, and also significantly inhibited neutrophil chemokine production. In contrast, the drug did not affect H. pylori colonization or acid secretion. FR167653 did not cause any pathological change in the gastric mucosa of normal animals. These results indicate that p38 kinase plays a crucial role in H. pylori-induced gastritis in Mongolian gerbils.     

p38丝裂素活化蛋白激酶与周期性张应力介导牙周膜成纤维细胞的增殖

背景:体内环境的复杂多变,使得在体外研究机械应力对细胞的作用存在着一定难度。目的:探讨p38丝裂素活化蛋白激酶信号通路在周期性张应力对人牙周膜成纤维细胞增殖中所产生的影响及其机制。方法:构建人牙周膜成纤维细胞体外培养-力学刺激模型,利用多通道细胞牵张应力加载系统,分别对细胞加以1,6,12,24h的周期性张应力,不加力组作为对照组,并在对照组和加力12h组分别加入p38丝裂素活化蛋白激酶特异性抑制剂SB203580。细胞计数试剂8检测细胞增殖情况;RT-PCR检测细胞和增殖细胞核抗原的表达。结果与结论:加力1h时细胞增殖得到促进,6h时继续上升,12h时达到高峰,24h增殖受到抑制;SB203580可抑制细胞增殖和增殖细胞核抗原mRNA的表达。说明在一定时间范围内,周期性张应力可促进人牙周膜成纤维细胞增殖,但随时间延长,增殖受到抑制;p38丝裂素活化蛋白激酶信号通路在周期性张应力介导的人牙周膜成纤维细胞增殖中发挥重要作用。     

Selective activation and functional significance of p38alpha mitogen-activated protein kinase in lipopolysaccharide-stimulated neutrophils

Activation of leukocytes by proinflammatory stimuli selectively initiates intracellular signal transduction via sequential phosphorylation of kinases. Lipopolysaccharide (LPS) stimulation of human neutrophils is known to result in activation of p38 mitogen-activated protein kinase (MAPk); however, the upstream activator(s) of p38 MAPk is unknown, and consequences of p38 MAPk activation remain largely undefined. We investigated the MAPk kinase (MKK) that activates p38 MAPk in response to LPS, the p38 MAPk isoforms that are activated as part of this pathway, and the functional responses affected by p38 MAPk activation. Although MKK3, MKK4, and MKK6 all activated p38 MAPk in experimental models, only MKK3 was found to activate recombinant p38 MAPk in LPS-treated neutrophils. Of p38 MAPk isoforms studied, only p38alpha and p38delta were detected in neutrophils. LPS stimulation selectively activated p38alpha. Specific inhibitors of p38alpha MAPk blocked LPS-induced adhesion, nuclear factor-kappa B (NF-kappaB) activation, and synthesis of tumor necrosis factor-alpha (TNF-alpha). Inhibition of p38alpha MAPk resulted in a transient decrease in TNF-alpha mRNA accumulation but persistent loss of TNF-alpha synthesis. These findings support a pathway by which LPS stimulation of neutrophils results in activation of MKK3, which in turn activates p38alpha MAPk, ultimately regulating adhesion, NF-kappaB activation, enhanced gene expression of TNF-alpha, and regulation of TNF-alpha synthesis.     

p38 mitogen-activated protein kinase inhibitors--mechanisms and therapeutic potentials.

The pyridinylimidazole compounds, exemplified by SB 203580, originally were prepared as inflammatory cytokine synthesis inhibitors. Subsequently, the compounds were found to be selective inhibitors for p38 mitogen-activated protein kinase (MAPK), a member of the MAPK family. SB 203580 inhibits the catalytic activity of p38 MAPK by competitive binding in the ATP pocket. Four homologues of p38 MAPK have been identified to date, and interestingly, their biochemical properties and their respective sensitivities to the inhibitors are distinct. X-ray crystallographic analysis of p38-inhibitor complexes reinforces the observations made from site-directed mutagenesis studies, thereby providing a molecular basis for understanding the kinase selectivity of these inhibitors. The p38 MAPK inhibitors are efficacious in several disease models, including inflammation, arthritis and other joint diseases, septic shock, and myocardial injury.     

RWJ 67657, a potent, orally active inhibitor of p38 mitogen-activated protein kinase.

Tumor necrosis factor-alpha (TNF-alpha), a cytokine secreted by activated monocytes/macrophages and T lymphocytes, has been implicated in several disease states, including rheumatoid arthritis, inflammatory bowel disease, septic shock, and osteoporosis. Monocyte/macrophage production of TNF-alpha is dependent on the mitogen-activated protein kinase p38. RWJ 67657 (4-[4-(4-fluorophenyl)-1-(3-phenylpropyl)-5-(4-pyridinyl)-1H-imidazol -2-yl]-3-butyn-1-ol) inhibited the release of TNF-alpha by lipopolysaccharide (a monocyte stimulus)-treated human peripheral blood mononuclear cells with an IC(50) of 3 nM, as well as the release of TNF-alpha from peripheral blood mononuclear cells treated with the superantigen staphylococcal enterotoxin B (a T cell stimulus), with an IC(50) value of 13 nM. This compound was approximately 10-fold more potent than the literature standard p38 kinase inhibitor SB 203580 in all p38 dependent in vitro systems tested. RWJ 67657 inhibited the enzymatic activity of recombinant p38alpha and beta, but not gamma or delta, in vitro and had no significant activity against a variety of other enzymes. In contrast, SB 203580 significantly inhibited the tyrosine kinases p56 lck and c-src (IC(50) = 5 microM). RWJ 67657 did not inhibit T cell production of interleukin-2 or interferon-gamma and did not inhibit T cell proliferation in response to mitogens. RWJ 67657 inhibited TNF-alpha production in lipopolysaccharide-injected mice (87% inhibition at 50 mg/kg) and in rats (91% inhibition at 25 mg/kg) after oral administration. Based on these favorable biological properties, RWJ 67657 may have use as a treatment for inflammatory diseases.     

Pamapimod, a novel p38 mitogen-activated protein kinase inhibitor: preclinical analysis of efficacy and selectivity

P38alpha is a protein kinase that regulates the expression of inflammatory cytokines, suggesting a role in the pathogenesis of diseases such as rheumatoid arthritis (RA) or systemic lupus erythematosus. Here, we describe the preclinical pharmacology of pamapimod, a novel p38 mitogen-activated protein kinase inhibitor. Pamapimod inhibited p38alpha and p38beta enzymatic activity, with IC(50) values of 0.014 +/- 0.002 and 0.48 +/- 0.04 microM, respectively. There was no activity against p38delta or p38gamma isoforms. When profiled across 350 kinases, pamapimod bound only to four kinases in addition to p38. Cellular potency was assessed using phosphorylation of heat shock protein-27 and c-Jun as selective readouts for p38 and c-Jun NH(2)-terminal kinase (JNK), respectively. Pamapimod inhibited p38 (IC(50), 0.06 microM), but inhibition of JNK was not detected. Pamapimod also inhibited lipopolysaccharide (LPS)-stimulated tumor necrosis factor (TNF) alpha production by monocytes, interleukin (IL)-1beta production in human whole blood, and spontaneous TNFalpha production by synovial explants from RA patients. LPS- and TNFalpha-stimulated production of TNFalpha and IL-6 in rodents also was inhibited by pamapimod. In murine collagen-induced arthritis, pamapimod reduced clinical signs of inflammation and bone loss at 50 mg/kg or greater. In a rat model of hyperalgesia, pamapimod increased tolerance to pressure in a dose-dependent manner, suggesting an important role of p38 in pain associated with inflammation. Finally, an analog of pamapimod that has equivalent potency and selectivity inhibited renal disease in lupus-prone MRL/lpr mice. Our study demonstrates that pamapimod is a potent, selective inhibitor of p38alpha with the ability to inhibit the signs and symptoms of RA and other autoimmune diseases.     

参与骨关节炎的P38丝裂原活化蛋白激酶信号转导通路

背景：p38丝裂原活化蛋白激酶信号转导通路属于丝裂原活化蛋白激酶家族成员,在骨关节炎的发生发展中发挥重要作用。目的：对骨关节炎病理进程中 p38丝裂原活化蛋白激酶信号转导通路相关作用机制的研究进展进行综述。方法：由第一作者用计算机检索中国期刊全文数据库和 PubMed 数据库,检索词分别为“p38丝裂原活化蛋白激酶信号通路、骨关节炎、关节软骨、软骨细胞”和“p38MAPK signal transduction pathway, osteoarthritis, Articular cartilage,Chondrocyte”。从 p38丝裂原活化蛋白激酶信号通路简介,p38丝裂原活化蛋白激酶在骨关节炎中的作用,p38丝裂原活化蛋白激酶阻断剂在骨关节炎中的应用3方面进行总结。共检索到可应用文献90篇,按纳入标准对文献进行筛选,共纳入46篇文章。结果与结论：p38丝裂原活化蛋白激酶信号通路与软骨细胞的肥大化和钙化、软骨细胞的凋亡、软骨基质金属蛋白酶的合成、软骨炎性细胞因子的产生等有密切关系,对骨关节炎的发生发展有重要影响。p38丝裂原活化蛋白激酶通过多种复杂的机制参与骨关节炎的形成和发展,对其起到极其重要的作用,因此阻断 p38丝裂原活化蛋白激酶信号通路可能成为骨关节炎治疗的新靶点。     

达格列净通过p38丝裂原活化蛋白激酶抑制高糖诱导的人肾小球足细胞损伤

目的 探讨达格列净通过p38丝裂原活化蛋白激酶（p38 MAPK）信号通路对D-葡萄糖诱导的人肾小球足细胞凋亡、自噬、炎症反应及氧化损伤的影响。方法 体外培养人肾小球足细胞（HGPCs），分为对照组（5 mmol/L D-葡萄糖）、D-葡萄糖组（30 mmol/L D-葡萄糖）、达格列净组（30 mmol/L D-葡萄糖＋50 μmol/L达格列净）、抑制剂组（30 mmol/L D-葡萄糖＋10 μmol/L p38 MAPK通路抑制剂SB 203580）、达格列净＋抑制剂组（30 mmol/L D-葡萄糖＋50 μmol/L达格列净＋10 μmol/L SB 203580）和达格列净＋激活剂组（30 mmol/L D-葡萄糖＋50 μmol/L达格列净＋10 μmol/L p38 MAPK通路激活剂C16-PAF）。对照组与D-葡萄糖组用D-葡萄糖干预24 h；其他组D-葡萄糖干预24 h后相应药物继续干预 24 h。采用细胞计数试剂盒-8（CCK-8）检测细胞活力；采用Hoechst 33258染色法检测细胞凋亡率；采用ELISA检测白细胞介素（IL）-1β、IL-6、肿瘤坏死因子α（TNF-α）、丙二醇（MDA）和超氧化物歧化酶（SOD）的表达水平；采用实时荧光定量PCR（RT-qPCR）检测酵母ATG6同源物（Beclin-1）、微管相关蛋白1轻链3 Ⅱ（LC3 Ⅱ）mRNA表达水平；采用Western印迹法检测Beclin-1、LC3 Ⅱ、p53、p38 MAPK及p-p38 MAPK蛋白表达。结果 与对照组相比，D-葡萄糖组细胞活力降低（P＜0.05），达格列净组细胞活力升高（P＜0.05），细胞凋亡率，IL-1β、IL-6、TNF-α、MDA、Beclin-1、LC3 ⅡmRNA和蛋白、p53和p-p38 MAPK蛋白水平升高（P＜0.05），SOD水平降低（P＜0.05）。与D-葡萄糖组相比，达格列净组和抑制剂组细胞凋亡率、IL-1β、IL-6、TNF-α、MDA、Beclin-1、LC3 ⅡmRNA和蛋白、p53和p-p38 MAPK蛋白水平降低（P＜0.05），SOD水平升高（P＜0.05）。与达格列净组相比，达格列净＋抑制剂组细胞凋亡率、IL-1β、IL-6、TNF-α、MDA、Beclin-1、LC3 Ⅱ mRNA和蛋白、p53和p-p38 MAPK蛋白水平进一步降低（P＜0.05），SOD水平进一步升高（P＜0.05）；达格列净＋激活剂组与达格列净＋抑制剂组变化趋势相反，与达格列净组差异有统计学意义（P＜0.05）。结论 达格列净可抑制高糖诱导的人HGPCs的凋亡、自噬、炎症反应及氧化损伤，其作用机制可能与抑制p38 MAPK通路信号转导相关。     

Glucose or diabetes activates p38 mitogen-activated protein kinase via different pathways

Hyperglycemia can cause vascular dysfunctions by multiple factors including hyperosmolarity, oxidant formation, and protein kinase C (PKC) activation. We have characterized the effect of hyperglycemia on p38 mitogen-activated protein (p38) kinase activation, which can be induced by oxidants, hyperosmolarity, and proinflammatory cytokines, leading to apoptosis, cell growth, and gene regulation. Glucose at 16.5 mM increased p38 kinase activity in a time-dependent manner compared with 5.5 mM in rat aortic smooth muscle cells (SMC). Mannitol activated p38 kinase only at or greater than 22 mM. High glucose levels and a PKC agonist activated p38 kinase, and a PKC inhibitor, GF109203X, prevented its activation. However, p38 kinase activation by mannitol or tumor necrosis factor-α was not inhibited by GF109203X. Changes in PKC isoform distribution after exposure to 16.5 mM glucose in SMC suggested that both PKC-β2 and PKC-δ isoforms were increased. Activities of p38 kinase in PKC-δ– but not PKC-β1–overexpressed SMC were increased compared with control cells. Activation of p38 kinase was also observed and characterized in various vascular cells in culture and aorta from diabetic rats. Thus, moderate hyperglycemia can activate p38 kinase by a PKC-δ isoform–dependent pathway, but glucose at extremely elevated levels can also activate p38 kinase by hyperosmolarity via a PKC-independent pathway.     

p38 mitogen-activated protein kinase targets the production of proinflammatory endothelial microparticles

Summary.  Background: Endothelial microparticles (EMPs) are irregularly shaped membrane fragments shed into the circulation in patients with vascular diseases, and may themselves act to enhance the endothelial response to inflammation. On the basis of the importance of p38 mitogen-activated protein kinase (MAPK) in endothelial responses to inflammatory stimuli, we sought to define the role of p38 in EMP generation and function. Methods: Microparticle generation from cultures of human aortic endothelial cells (hAECs) treated with tumor necrosis factor-α (TNF-α) and p38 inhibition was quantified via multiple modalities. The response of target endothelial cells was assessed by treatment of cells with EMPs generated under various conditions. Results: Inhibition of p38 in hAECs, using pharmacologic agents, resulted in a 50% reduction of TNF-α-induced EMPs. Importantly, suppression of microparticles was specific to p38 MAPK pathways. EMPs triggered by TNF-α activation induced an approximately four-fold increase in soluble intercellular adhesion molecule-1 (sICAM-1) release from targeted cells. However, inhibition of p38 MAPK in the targeted cell prior to EMP treatment did not alter the sICAM1 response. Conclusions: Our findings implicate p38 MAPK signaling as significant and selective in the formation and maturation of EMPs. EMPs elicited a proinflammatory response from targeted hAECs that was dependent on the conditions under which EMPs were generated. However, our results imply a unidirectional model in which p38 MAPK is critical at the source of microparticle formation, but not the target cell response to EMPs. These findings indicate a novel mechanism by which p38 inhibition may offer therapeutic benefit in vivo via direct inhibition of EMP formation .     

Suppression of phosphorylation of extracellular-signal-regulated kinase and p38 mitogen-activated protein kinase in polymorphonuclear leukocytes by the proton pump inhibitor lansoprazole

Lansoprazole (LPZ) is a proton pump inhibitor that suppresses gastric secretion and exerts anti-inflammatory effects on immune cells. Recently, LPZ has been used for the treatment of peptic ulcer and gastritis, which can be caused by Helicobacter pylori, due to its potent acid-suppressive effects. We focused the aim to the anti-inflammatory effects on the over-activation of neutrophils, and investigated the effects of LPZ on the signal transduction of the mitogen-activated protein kinase (MAPK) family. LPZ slightly phosphorylated p38 MAPK of neutrophils at a concentration of 10 μg/ml, but did not phosphorylate extracellular-signal regulated kinase (ERK) 1/2. Pretreatment of neutrophils with (1–5 μg/ml) LPZ strongly attenuated the phorbol-12-myristate-13-acetate-stimulated phosphorylation of ERK1/2, and LPZ slightly suppressed the lipopolysaccharide (LPS)- and N-formylmethionylleucylphenylalanine-stimulated phosphorylation of p38. ERK1/2 produces the mitochondrial anti-apoptotic proteins, and the signaling pathway from LPS and N-formylmethionylleucylphenylalanine to p38 is the main pathway for reactive oxygen species production. The mechanism of anti-inflammatory effect of LPZ on hyper-activated neutrophils is suggested to be the suppression of signal transduction of ERK1/2 and p38 MAPK.     

Selective inhibitor of p38 mitogen-activated protein kinase inhibits lipopolysaccharide-induced interleukin-8 expression in human pulmonary vascular endothelial cells

Adult respiratory distress syndrome (ARDS) characterized by permeability edema is observed in severe insults such as bacteremia sepsis. Interleukin (IL)-8, which chemoattracts and activates neutrophils, has been suggested to play an important role in the production of ARDS. Therefore, the inhibition of IL-8 production is an important strategy for the treatment of ARDS. Recent studies have revealed the role of p38 mitogen-activated protein (MAP) kinase in cytokine expression and the inhibition by a selective inhibitor of p38 MAP kinase activity of cytokine expression in a variety of cell types. However, little is known about the role of p38 MAP kinase in lipopolysaccharide (LPS)-induced IL-8 expression in pulmonary vascular endothelial cells and the effect of a selective p38 MAP kinase inhibitor on it. In the present study, we therefore attempted to clarify these issues. The results showed that LPS induced p38 MAP kinase phosphorylation and activity, and SB 203580 as a selective inhibitor of p38 MAP kinase activity inhibited p38 MAP kinase activity and IL-8 expression in LPS-stimulated pulmonary vascular endothelial cells. These results indicate that p38 MAP kinase regulates LPS-induced IL-8 expression in pulmonary vascular endothelial cells. Although it is currently not known whether SB 203580 is capable of producing beneficial effects on ARDS, a strategy of inhibiting p38 MAP kinase activity by a selective p38 MAP kinase inhibitor may apply to the therapy for ARDS.     

Role of p38 mitogen-activated protein kinase in lung injury after burn trauma

This study was undertaken to evaluate the effect of SB203580, a specific p38 mitogen-activated protein (MAP) kinase inhibitor, on burn-induced lung injury as well as the release of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta in rats to characterize the role of p38 MAP kinase in lung injury after burn trauma. Sprague-Dawley rats were divided into three groups: 1) sham group, or rats who underwent sham burn; 2) control group, or rats given third-degree burns over 30% total body surface area (TBSA) and lactated Ringer solution for resuscitation; and 3) SB203580 group, or rats given burn injury and lactated Ringers solution with SB203580 inside for resuscitation. Pulmonary injury was assessed at 24 h by pulmonary capillary permeability determined with fluorescein isothiocyanate-labeled albumin and lung histologic analysis. TNF-alpha and IL-1beta protein in bronchoalveolar lavage fluid and serum were measured by enzyme-linked immunosorbent assay and p38 MAP kinase was activity determined in lung by Western blot analysis. These studies showed that significant activation of p38 MAP kinase at 24 h postburn compared with control. Burn trauma resulted in increased pulmonary capillary leakage permeability, elevated levels of TNF-alpha and IL-1beta in bronchoalveolar lavage fluid and serum, and worsened histologic condition. SB203580 inhibited the activation of p38 MAP kinase, reduced the levels of TNF-alpha and IL-1beta, and prevented burn-mediated lung injury. These data suggest that p38 MAP kinase activation is one important aspect of the signaling event that may mediate the release of TNF-alpha and IL-1beta and contributes to burn-induced lung injury.     

Inhibition of p38 mitogen-activated protein kinase provides neuroprotection in cerebral focal ischemia

Mitogen-activated protein kinases (MAPKs) are involved in many cellular processes. The stress-activated MAPK, p38, has been linked to inflammatory cytokine production and cell death following cellular stress. Here, we demonstrate focal ischemic stroke-induced p38 enzyme activation (i.e., phosphorylation) in the brain. The second generation p38 MAPK inhibitor SB 239063 was identified to exhibit increased kinase selectivity and improved cellular and in vivo activity profiles, and thus was selected for evaluation in two rat models of permanent focal ischemic stroke. SB 239063 was administered orally pre- and post-stroke and intravenously post-stroke. Plasma concentration levels were achieved in excess of those that effectively inhibit p38 activity. In both moderate and severe stroke, SB 239063 reduced infarct size by 28-41%, and neurological deficits by 25-35%. In addition, neuroprotective plasma concentrations of SB 239063 that reduced p38 activity following stroke also reduced the stroke-induced expression of IL-1beta and TNFalpha (i.e., cytokines known to contribute to stroke-induced brain injury). SB 239063 also provided direct protection of cultured brain tissue to in vitro ischemia. This robust SB 239063-induced neuroprotection emphasizes a significant opportunity for targeting MAPK pathways in ischemic stroke injury, and also suggests that p38 inhibition be evaluated for protective effects in other experimental models of nervous system injury and neurodegeneration.     

p38alpha-selective mitogen-activated protein kinase inhibitor SD-282 reduces inflammation in a subchronic model of tobacco smoke-induced airway inflammation

Chronic obstructive pulmonary disease (COPD) is characterized by pulmonary inflammation, which is relatively insensitive to inhaled corticosteroids. The extent of the pulmonary inflammation in COPD correlates with disease severity, and it is thought to play a significant role in disease progression. We have evaluated a selective p38alpha-selective mitogen-activated protein kinase (MAPK) inhibitor, indole-5-carboxamide (ATP-competitive inhibitor of p38 kinase) (SD-282), in an 11-day model of tobacco smoke (TS)-induced pulmonary inflammation in A/J mice, by using dexamethasone as a reference steroid. Two oral treatment paradigms were evaluated in this TS model: prophylactic with daily pretreatment before each daily exposure, and therapeutic with daily treatment for 6 days commencing after 5 days of smoke exposure. Bronchoalveolar lavage and histological evaluation of lung sections taken after exposure to TS revealed an inflammatory response composed of increased numbers of macrophages and neutrophils and enhanced mucin staining. Phospho-p38 staining in macrophages and type II epithelial cells after TS exposure was also observed. Given prophylactically or therapeutically, dexamethasone failed to inhibit any of the TS-induced inflammatory changes. By contrast, SD-282 inhibited TS-induced increases in macrophages and neutrophils. Furthermore, SD 282 reduced TS-induced increases in cyclooxygenase-2 and interleukin-6 levels, and phospho-p38 expression in the lungs. In conclusion, SD-282 markedly reduced TS-induced inflammatory responses when given prophylactically or therapeutically whereas dexamethasone was ineffective. This is the first evidence that a p38alpha-selective MAPK inhibitor can exert pulmonary anti-inflammatory activity in a TS exposure model when given in a therapeutic mode, establishing the potential of p38 MAPK inhibitors as a therapy for COPD.