Possible involvement of CCL1-CCR8 interaction in lymphocytic recruitment in IgG4-related sclerosing cholangitis.

BACKGROUND & AIMS: IgG4-related sclerosing cholangitis and type 1 autoimmune pancreatitis (IgG4-SC/AIP) are characterized by massive lymphoplasmacytic infiltration including Th2 and regulatory T cells (Tregs). This study was conducted to address which chemotactic factors are involved in this condition. METHODS: Chemokine expression profiles in tissue were examined in IgG4-SC/AIP (n=17), classical primary sclerosing cholangitis (IgG4(low) PSC, n=17), PSC with elevated serum/tissue IgG4 levels (IgG4(high) PSC, n=5), and primary biliary cirrhosis (n=7). We focused on five chemotactic factors/receptors (CCL1-CCR8, CCL17/CCL22-CCR4), given that CCR4 and CCR8 are predominantly expressed in both Th2 and Tregs. RESULTS: In conjunction with higher expression levels of IL-4 and IL-10, expression values of CCL1 and CCR8 transcripts were significantly higher in IgG4-SC/AIP than in IgG4(low) PSC (p=0.002) and IgG4(high) PSC (p=0.023). CCL1 and CCR8 were also overexpressed in IgG4(high) PSC than in IgG4(low) PSC (p=0.023). No difference was seen for CCL17, CCL22, and CCR4. In situ hybridization revealed CCL1 to be predominantly expressed in the pancreatic duct epithelium, peribiliary glands, and vascular endothelial cells including the ones involved in obliterative phlebitis in IgG4-SC/AIP, in contrast to IgG4(high) PSC where this chemotactic factor was positive in several infiltrating lymphocytes. These CCL1-expressing sites were infiltrated by CCR8(+) lymphocytes. On immunohistochemistry, GATA3(+) Th2 lymphocytes and FOXP3(+) Tregs were significantly larger in number in IgG4-SC/AIP, with the GATA3(+)/T-bet(+) cell ratio to be shifted in favour of Th2 in periductal and perivascular areas. CONCLUSIONS: CCL1-CCR8 interaction may play a critical role in lymphocytic recruitment in IgG4-SC/AIP, leading to duct-centred inflammation and obliterative phlebitis.

CCL-1 in the spinal cord contributes to neuropathic pain induced by nerve injury.

Cytokines such as interleukins are known to be involved in the development of neuropathic pain through activation of neuroglia. However, the role of chemokine (C-C motif) ligand 1 (CCL-1), a well-characterized chemokine secreted by activated T cells, in the nociceptive transmission remains unclear. We found that CCL-1 was upregulated in the spinal dorsal horn after partial sciatic nerve ligation. Therefore, we examined actions of recombinant CCL-1 on behavioural pain score, synaptic transmission, glial cell function and cytokine production in the spinal dorsal horn. Here we show that CCL-1 is one of the key mediators involved in the development of neuropathic pain. Expression of CCL-1 mRNA was mainly detected in the ipsilateral dorsal root ganglion, and the expression of specific CCL-1 receptor CCR-8 was upregulated in the superficial dorsal horn. Increased expression of CCR-8 was observed not only in neurons but also in microglia and astrocytes in the ipsilateral side. Recombinant CCL-1 injected intrathecally (i.t.) to naive mice induced allodynia, which was prevented by the supplemental addition of N-methyl-D-aspartate (NMDA) receptor antagonist, MK-801. Patch-clamp recordings from spinal cord slices revealed that application of CCL-1 transiently enhanced excitatory synaptic transmission in the substantia gelatinosa (lamina II). In the long term, i.t. injection of CCL-1 induced phosphorylation of NMDA receptor subunit, NR1 and NR2B, in the spinal cord. Injection of CCL-1 also upregulated mRNA level of glial cell markers and proinflammatory cytokines (IL-1ß, TNF-α and IL-6). The tactile allodynia induced by nerve ligation was attenuated by prophylactic and chronic administration of neutralizing antibody against CCL-1 and by knocking down of CCR-8. Our results indicate that CCL-1 is one of the key molecules in pathogenesis, and CCL-1/CCR-8 signaling system can be a potential target for drug development in the treatment for neuropathic pain.

Restraint stress alters neutrophil and macrophage phenotypes during wound healing.

Previous studies reported that stress delays wound healing, impairs bacterial clearance, and elevates the risk for opportunistic infection. Neutrophils and macrophages are responsible for the removal of bacteria present at the wound site. The appropriate recruitment and functions of these cells are necessary for efficient bacterial clearance. In our current study we found that restraint stress induced an excessive recruitment of neutrophils extending the inflammatory phase of healing, and the gene expression of neutrophil attracting chemokines MIP-2 and KC. However, restraint stress did not affect macrophage infiltration. Stress decreased the phagocytic abilities of phagocytic cells ex vivo, yet it did not affect superoxide production. The cell surface expression of adhesion molecules CD11b and TLR4 were decreased in peripheral blood monocytes in stressed mice. The phenotype of macrophages present at the wound site was also altered. Gene expression of markers of pro-inflammatory classically activated macrophages, CXCL10 and CCL5, were down-regulated; as were markers associated with wound healing macrophages, CCL22, IGF-1, RELMα; and the regulatory macrophage marker, chemokine CCL1. Restraint stress also induced up-regulation of IL10 gene expression. In summary, our study has shown that restraint stress suppresses the phenotype shift of the macrophage population, as compared to the changes observed during normal wound healing, while the number of macrophages remains constant. We also observed a general suppression of chemokine gene expression. Modulation of the macrophage phenotype could provide a new therapeutic approach in the treatment of wounds under stress conditions in the clinical setting.

CCL1 released from M2b macrophages is essentially required for the maintenance of their properties.

Patients with 10-30 days postburn injury are greatly susceptible to infections. M1M (IL-10(-)IL-12(+) M) are essential cells in host antibacterial innate immunity against MRSA infections. However, these effector cells are not easily generated in hosts who are carriers of M2bM (IL-12(-)IL-10(+)CCL1(+)LIGHT(+) M). M2bM are inhibitory on M1M generation. In this study, the antibacterial resistance of mice, 10-30 days postburn injury against MRSA infection, was improved by the modulation of M2bM activities. Unburned mice inoculated with M preparations from mice, 10-30 days after burn injury, were susceptible to MRSA infection, whereas unburned mice, inoculated with M preparations from the same mice that were previously treated with CCL1 antisense ODN, were resistant to the infection. M2bM, isolated from Day 15 burn mice, lost their M2bM properties 3 days after cultivation under frequent medium changes, whereas their M2bM properties remained in the same cultures supplemented with rCCL1. In cultures, M preparations from Day 15 burn mice treated with CCL1 antisense ODN did not produce CCL1 and did convert to M1M after heat-killed MRSA stimulation. Also, Day 15 burn mice treated with the ODN became resistant against MRSA infection. These results indicate that CCL1 released from M2bM is essentially required for the maintenance of their properties. The increased susceptibility of mice, 10-30 days after burn injury to MRSA infection, may be controlled through the intervention of CCL1 production by M2bM appearing in association with severe burn injuries.

Selective deregulation in chemokine signaling pathways of CD4+CD25(hi)CD127(lo)/(-) regulatory T cells in human allergic asthma.

BACKGROUND: CD4+CD25(hi)CD127(lo)/(-) regulatory T cells have been suggested to be critical regulators of inflammatory processes in allergic asthma. Recent studies reported a selective decrease in the frequency of regulatory T cells in the bronchoalveolar lavage fluid of allergic asthmatic (AA) subjects, prompting the possibility of defective recruitment of these cells to the airway in response to chemokines produced during asthmatic inflammation. OBJECTIVES: This study aimed to characterize the chemotactic profile of circulating regulatory T cells in AA subjects in response to chemokines abundantly produced in airway inflammation, such as CCL1, CCL17, and CCL22. METHODS: The study was performed in a cohort of 26 AA, 16 healthy control, and 16 non-AA subjects. We used chemotaxis assays to evaluate cell migration, flow cytometry to examine chemokine receptor expression, and phospho-ELISA to study consequent signaling pathways in regulatory T cells. RESULTS: Regulatory T cells, but not CD4+CD25(-)T cells, from AA subjects showed decreased chemotactic responses, specifically to CCL1, in comparison with their healthy control and non-AA counterparts. Decreased CCL1-mediated chemotaxis in AA regulatory T cells was associated with decreased phosphorylation of protein kinase B (AKT), a protein involved in chemokine intracellular signaling. Furthermore, the decreased chemotactic response to CCL1 in AA regulatory T cells significantly correlated with asthma severity and decreased pulmonary function in AA subjects. CONCLUSIONS: These results provide the first evidence of dysfunction in the chemokine signaling pathway in AA regulatory T cells.

IL-12 produced by dendritic cells augments CD8+ T cell activation through the production of the chemokines CCL1 and CCL17.

IL-12 family members are an important link between innate and adaptive immunity. IL-12 drives Th1 responses by augmenting IFN-gamma production, which is key for clearance of intracellular pathogens. IL-23 promotes the development of IL-17-producing CD4(+) T cells that participate in the control of extracellular pathogens and the induction of autoimmunity. However, recent studies have shown that these cytokines can modulate lymphocyte migration and cellular interactions. Therefore, we sought to determine the individual roles of IL-12 and IL-23 in naive CD8(+) T cell activation by addressing their ability to influence IFN-gamma production and cellular interaction dynamics during priming by Listeria monocytogenes-infected dendritic cells (DC). We found that IL-12 was the major cytokine influencing the level of IFN-gamma production by CD8(+) T cells while IL-23 had little effect on this response. In addition, we observed that IL-12 promoted longer duration conjugation events between CD8(+) T cells and DC. This enhanced cognate interaction time correlated with increased production of the chemokines CCL1 and CCL17 by WT but not IL-12-deficient DC. Neutralization of both chemokines resulted in reduced interaction time and IFN-gamma production, demonstrating their importance in priming naive CD8(+) T cells. Our study demonstrates a novel mechanism through which IL-12 augments naive CD8(+) T cell activation by facilitating chemokine production, thus promoting more stable cognate interactions during priming.