Genetic Ablation of CXCR2 Protects against Cigarette Smoke-Induced Lung Inflammation and Injury

Abstract

Antagonism of CXCR2 receptors, predominately located on neutrophils and critical for their immunomodulatory activity, is an attractive pharmacological therapeutic approach aimed at reducing the potentially damaging effects of heightened neutrophil influx into the lung. The role CXCR2 in lung inflammation in response to cigarette smoke (CS) inhalation using the mutant mouse approach is not known. We hypothesized that genetic ablation of CXCR2 would protect mice against CS-induced inflammation and DNA damage response. We used CXCR2−/− deficient/mutant (knock-out, KO) mice, and assessed the changes in critical lung inflammatory NF-κB-driven chemokines released from the parenchyma of CS-exposed mice. The extent of tissue damage was assessed by the number of DNA damaging γH2AX positive cells. CXCR2 KO mice exhibited protection from heightened levels of neutrophils measured in BALF taken from mice exposed to CS. IL-8 (KC mouse) levels in the BALF from CS-exposed CXCR2 KO were elevated compared to WT. IL-6 levels in BALF were refractory to increase by CS in CXCR2 KO mice. There were no significant changes to MIP-2, MCP-1, or IL-1β. Total levels of NF-κB were maintained at lower levels in CS-exposed CXCR2 KO mice compared to WT mice exposed to CS. Finally, CXCR2 KO mice were protected from lung cells positive for DNA damage response and senescence marker γH2AX. CXCR2 KO mice are protected from heightened inflammatory response mediated by increased neutrophil response as a result of acute 3 day CS exposure. This is also associated with changes in pro-inflammatory chemokines and reduced incursion of γH2AX indicating CXCR2 deficient mice are protected from lung injury. Thus, CXCR2 may be a pharmacological target in setting of inflammation and DNA damage in the pathogenesis of COPD.

Therapeutic blockade of CXCR2 rapidly clears inflammation in arthritis and atopic dermatitis models: demonstration with surrogate and humanized antibodies

“…54 Several previous inflammatory disease model studies showed that blocking or eliminating CXCR2 + cells is highly effective in reducing excessive leukocyte recruitment to inflammation sites. 18,19 Remarkably, Ly6C + macrophage numbers were higher in the inflamed joints. These cells are most likely recently accumulated to the joints in response to inflammation and are derived from circulating Ly6C + monocytes.…”

“…16,17 Several inflammatory disease model studies showed that blocking or eliminating CXCR2 + cells is highly effective in reducing excessive leukocyte recruitment to the sites of inflammation. 18,19 The role of this receptor in regulating neutrophil recruitment is now better established using CXCR2 knockout strategies. 10 Indeed, CXCR2-deficient mice show impaired neutrophil recruitment into the peritoneal cavity, 20 lung, 21 and the skin.…”

Role of inflammatory cells in airway remodeling in COPD

“… 37 Further studies demonstrated that knockout of CXCR2, a receptor of IL-8, protected mice from cigarette smoke-induced lung inflammation and DNA damage in COPD pathogenesis. 38 …”

Porcine CXCR1/2 antagonist CXCL8(3–72)G31P inhibits lung inflammation in LPS-challenged mice

“…CXCL8 has been considered as an essential chemokine for neutrophil activation and recruitment. Blocking the binding of CXCL8 to its receptors, CXCR1/2, can effectively limit neutrophils recruitment and slow down inflammatory response 34,35 . In this study, the relationship between CXCR1/2 and swine pneumonia were determined using Real-Time PCR and immunohistochemical staining.…”