Kristin J. Carpenter

CCR1 and CC Chemokine Ligand 5 Interactions Exacerbate Innate Immune Responses during Sepsis

CCR1 has previously been shown to play important roles in leukocyte trafficking, pathogen clearance, and the type 1/type 2 cytokine balance, although very little is known about its role in the host response during sepsis. In a cecal ligation and puncture model of septic peritonitis, CCR1-deficient (CCR1−/−) mice were significantly protected from the lethal effects of sepsis when compared with wild-type (WT) controls. The peritoneal and systemic cytokine profile in CCR1−/− mice was characterized by a robust, but short-lived and regulated antibacterial response. CCR1 expression was not required for leukocyte recruitment, suggesting critical differences extant in the activation of WT and CCR1−/− resident or recruited peritoneal cells during sepsis. Peritoneal macrophages isolated from naive CCR1−/− mice clearly demonstrated enhanced cytokine/chemokine generation and antibacterial responses compared with similarly treated WT macrophages. CCR1 and CCL5 interactions markedly altered the inflammatory response in vivo and in vitro. Administration of CCL5 increased sepsis-induced lethality in WT mice, whereas neutralization of CCL5 improved survival. CCL5 acted in a CCR1-dependent manner to augment production of IFN-γ and MIP-2 to damaging levels. These data illustrate that the interaction between CCR1 and CCL5 modulates the innate immune response during sepsis, and both represent potential targets for therapeutic intervention.

Human Pulmonary Fibroblasts Exhibit Altered Interleukin-4 and Interleukin-13 Receptor Subunit Expression in Idiopathic Interstitial Pneumonia

Abnormal proliferation of pulmonary fibroblasts is a prominent feature of chronic pulmonary fibrotic diseases such as idiopathic interstitial pneumonia (IIP), but it is not presently clear how this proliferative response by lung fibroblasts can be therapeutically modulated. In the present study, we examined whether it was possible to selectively target primary human pulmonary fibroblasts grown out of surgical lung biopsies (SLBs) from IIP patients based on their expression of interleukin-4 receptor (IL-4R) and IL-13R subunits. Pulmonary fibroblast lines cultured from patients with the severest form of IIP, namely usual interstitial pneumonia, exhibited the greatest gene and protein expression of IL-4Ralpha, IL-13Ralpha1, and IL-13Ralpha2 compared with primary pulmonary fibroblast lines grown from other IIP SLBs and normal SLBs. When exposed to increasing concentrations of a chimeric protein comprised of human IL-13 and a truncated version of Pseudomonas exotoxin (IL13-PE), the proliferation of primary usual interstitial pneumonia fibroblasts was inhibited to a much greater extent compared with fibroblast lines from nonspecific interstitial pneumonia and respiratory bronchiolitis/interstitial lung disease patient groups. Fibroblasts from normal patients exhibited minimal susceptibility to the cytotoxic effect of IL13-PE. IL13-PE-mediated targeting of IIP fibroblasts was dependent on their expression of IL-4Ralpha and IL-13Ralpha2. Thus, these data suggest that the abnormal proliferative properties of human lung fibroblasts from certain IIP patient groups can be modulated in a manner that is dependent on the IL-4 and IL-13 receptor subunit expression by these cells.

Aspergillus and asthma – any link?

The innate immune and acquired immune responses are not separate, parallel systems but form interdependent components of a single integrated immune response. This is nicely highlighted by an expanding database demonstrating that the innate immune response provides the acquired immune response with information about the origin of the antigen and the type of response required via pattern recognition receptors (PRRs). Aspergillus is among a growing list of allergens that can aggravate asthmatic responses. Significant pulmonary pathology is associated with Aspergillus-induced allergic and asthmatic lung disease characterized by increased Th2 cytokine generation, IgE and IgG, eosinophilia, airway hyper-responsiveness and airway remodeling. Experimental data from a model of chronic fungal asthma demonstrate that thymus associated and regulated chemokine (TARC/CCL17) and macrophage derived chemokine (MDC/CCL22), working via CCR4, directly impair the innate anti-fungal immune response, thereby promoting the maintenance of acquired Th2-mediated asthmatic disease. Both chemokines appear to accomplish this by regulating the expression of PRRs such as toll like receptors (TLRs) and triggering receptor expressed on myeloid cells (TREM-1) by immune cells. Thus, the link between Aspergillus and asthma appears to reside in the magnitude and appropriateness of the host innate immune response, and ongoing research is revealing promising targets for therapy.

Focal interstitial CC chemokine receptor 7 (CCR7) expression in idiopathic interstitial pneumonia

Background/Aims: Idiopathic interstitial pneumonias (IIPs) are a diverse grouping of chronic pulmonary diseases characterised by varying degrees of pulmonary fibrosis. The triggers of the fibroproliferative process in IIP remain enigmatic but recent attention has been directed towards chemokine involvement in this process. Methods: The expression of two chemokine receptors, CCR7 and CXCR4, and their respective ligands, CCL19, CCL21, and CXCL12, were examined in surgical lung biopsies (SLBs) from patients with IIP. Transcript and protein expression of these receptors and their ligands was compared with that detected in histologically normal margin SLBs. Results: CCR7 and CXCR4 were detected by gene array and real time polymerase chain reaction analysis and CCR7, but not CXCR4, expression was significantly raised in usual interstitial pneumonia (UIP) relative to biopsies from patients diagnosed with non-specific interstitial pneumonia (NSIP) or respiratory bronchiolitis/interstitial lung disease (RBILD). CCR7 protein was expressed in interstitial areas of all upper and lower lobe UIP SLBs analysed. CCR7 expression was present in 50% of NSIP SLBs, and CCR7 was restricted to blood vessels and mononuclear cells in 75% of RBILD SLBs. Immune cell specific CXCR4 expression was seen in IIP and normal margin biopsies. CCR7 positive areas in UIP biopsies were concomitantly positive for CD45 (the leucocyte common antigen) but CCR7 positive areas in all IIP SLBs lacked the haemopoietic stem cell antigen CD34, collagen 1, and α smooth muscle actin. Conclusion: This molecular and immunohistochemical analysis showed that IIPs are associated with abnormal CCR7 transcript and protein expression.

Immunosuppressive Effects of CCL17 on Pulmonary Antifungal Responses during Pulmonary Invasive Aspergillosis

ABSTRACT Aspergillus fumigatus-sensitized CCR4-deficient (CCR4−/−) mice exhibit an accelerated clearance of conidia during fungal asthma. In the present study, we examined the roles of CCL17 and CCL22, two CCR4 ligands, during pulmonary invasive aspergillosis in neutropenic mice. Kaplan-Meier survival curve analysis revealed that wild-type C57BL/6 (CCR4+/+) mice were significantly protected from the lethal effects of Aspergillus compared with their wild-type controls following systemic neutralization with anti-CCL17 but not anti-CCL22 antibodies. Systemic neutralization of CCL17 significantly increased whole-lung CCL2 levels. Mouse survival and histological analysis revealed that the receptor mediating the deleterious effects of CCL17 was CCR4 since mice genetically deficit in CCR4 (CCR4−/−) did not develop invasive aspergillosis. Enzyme-linked immunosorbent assay analysis of whole-lung samples at day 2 after conidial challenge in neutrophil-depleted CCR4−/− and CCR4+/+ mice revealed that whole-lung IL-12 levels were significantly increased in the CCR4−/− group compared with the wild-type group. Also at day 2 after conidial challenge, significantly greater numbers of CD11c+ F4/80+ and CD11c+/CD86+ but fewer CD3/NK1.1+ cells were present in the lungs of CCR4−/− mice compared with their wild-type counterparts. Thus, CCL17-CCR4 interactions dramatically impair the pulmonary antifungal response against A. fumigatus in neutropenic mice.

Triggering receptor expressed on myeloid cells-1 (TREM-1) modulates immune responses to aspergillus fumigatus during fungal asthma in mice

Triggering receptor expressed on myeloid cells-1 (TREM-1) expression is increased during pulmonary fungal infection suggesting that this receptor might be involved in anti-fungal immune responses. To address the role of TREM-1 in a murine model of fungal allergic airway disease, A. fumigatus-sensitized CBA/J mice received by intratracheal injection a mixture of live A. fumigatus conidia and one of a control adenovirus vector (Ad70), an adenovirus containing a gene encoding for the extracellular domain of mouse TREM-1 and the Fc portion of human IgG (AdTREM-1Ig; a soluble inhibitor of TREM-1 function), or an adenovirus containing mouse DAP12 (AdDAP12; DAP12 is an intracellular adaptor protein required for TREM-1 signaling), and examined at various days after challenge. Whole lung TREM-1 levels peaked at day 3 whereas circulating TREM-1 levels peaked at day 30 in this fungal asthma model. AdTREM-1Ig-treated mice exhibited significantly higher airway hyperresponsiveness following methacholine challenge compared with Ad70- and AdDAP12-treated mice. Whole lung analysis of AdTREM-1Ig treated mice revealed markedly higher amounts of fungal material compared with the other groups. ELISA analysis of whole lung and bronchoalveolar lavage samples indicated that several pro-allergic cytokine and chemokines including CCL17 and CCL22 were significantly increased in the AdTREM-1Ig group compared with the other groups. Finally, Pam3Cys and soluble Aspergillus antigens induced TREM-1 transcript expression in macrophages in a TLR2 dependent manner. In conclusion, TREM-1 modulates the immune response directed against A. fumigatus during experimental fungal asthma.

Therapeutic targeting of CCR1 attenuates established chronic fungal asthma in mice

1 CC chemokine receptor 1 (CCR1) represents a promising target in chronic airway inflammation and remodeling due to fungus‐associated allergic asthma. 2 The present study addressed the therapeutic effect of a nonpeptide CCR1 antagonist, BX‐471, in a model of chronic fungal asthma induced by Aspergillus fumigatus conidia. 3 BX‐471 treatment of isolated macrophages inhibited CCL22 and TNF‐α and promoted IL‐10 release. BX‐471 also increased toll like receptor‐9 (TLR9) and decreased TLR2 and TLR6 expression in these cells. 4 When administered daily by intraperitoneal injection, from days 15 to 30 after the initiation of chronic fungal asthma, BX‐471 (3, 10, or 30 mg kg−1) dose‐dependently reduced airway inflammation, hyper‐responsiveness, and remodeling at day 30 after conidia challenge. The maximal therapeutic effect was observed at the 10 mg kg−1 dose. 5 In summary, the therapeutic administration of BX‐471 significantly attenuated experimental fungal asthma via its effects on both innate and adaptive immune processes.

Intrapulmonary, Adenovirus-Mediated Overexpression of KARAP/DAP12 Enhances Fungal Clearance during Invasive Aspergillosis

ABSTRACT Herein, we report that the intrapulmonary delivery of an adenovirus vector expressing KARAP/DAP12, an adaptor protein expressed in granulocytes and mononuclear cells, enhanced fungal clearance during experimental invasive pulmonary aspergillosis in neutropenic mice.