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.

CC chemokine receptor 8 potentiates donor Treg survival and is critical for the prevention of murine graft-versus-host disease.

The infusion of donor regulatory T cells (Tregs) has been used to prevent acute graft-versus-host disease (GVHD) in mice and has shown promise in phase 1 clinical trials. Previous work suggested that early Treg migration into lymphoid tissue was important for GVHD prevention. However, it is unclear how and where Tregs function longitudinally to affect GVHD. To better understand their mechanism of action, we studied 2 Treg-associated chemokine receptors in murine stem cell transplant models. CC chemokine receptor (CCR) 4 was dispensable for donor Treg function in the transplant setting. Donor Tregs lacking CCR8 (CCR8(-/-)), however, were severely impaired in their ability to prevent lethal GVHD because of increased cell death. By itself, CCR8 stimulation was unable to rescue Tregs from apoptosis. Instead, CCR8 potentiated Treg survival by promoting critical interactions with dendritic cells. In vivo, donor bone marrow-derived CD11c(+) antigen-presenting cells (APCs) were important for promoting donor Treg maintenance after transplant. In contrast, host CD11c(+) APCs appeared to be dispensable for early activation and expansion of donor Tregs. Collectively, our data indicate that a sustained donor Treg presence is critical for their beneficial properties, and that their survival depends on CCR8 and donor but not host CD11c(+) APCs.

Hepatic macrophage migration and differentiation critical for liver fibrosis is mediated by the chemokine receptor C-C motif chemokine receptor 8 in mice.

UNLABELLED: Chemokines critically control the infiltration of immune cells upon liver injury, thereby promoting hepatic inflammation and fibrosis. The chemokine receptor CCR8 can affect trafficking of monocytes/macrophages, monocyte-derived dendritic cells (DCs) and T-helper cell (Th) subsets, but its role in liver diseases is currently unknown. To investigate the functional role of CCR8 in liver diseases, ccr8(-/-) and wild-type (WT) mice were subjected to chronic experimental injury models of carbon tetrachloride (CCl(4) ) administration and surgical bile duct ligation (BDL). CCR8 was strongly up-regulated in the injured liver. Ccr8(-/-) mice displayed attenuated liver damage (e.g., ALT, histology, and TUNEL) compared to WT mice and were also protected from liver fibrosis in two independent injury models. Flow cytometry revealed reduced infiltrates of liver macrophages, neutrophils and natural killer cells, whereas hepatic CD4(+) T cells increased. The main CCR8-expressing cells in the liver were hepatic macrophages, and CCR8 was functionally necessary for CCL1-directed migration of inflammatory but not for nonclassical monocytes into the liver. Moreover, the phenotype of liver macrophages from injured ccr8(-/-) animals was altered with increased expression of DC markers and enhanced expression of T-cell-attracting chemokine macrophage inflammatory protein 1-alpha (MIP-1α/CCL3). Correspondingly, hepatic CD4(+) T cells showed increased Th1 polarization and reduced Th2 cells in CCR8-deficient animals. Liver fibrosis progression, but also subsequent T-cell alterations, could be restored by adoptively transferring CCR8-expressing monocytes/macrophages into ccr8(-/-) mice during experimental injury. CONCLUSIONS: CCR8 critically mediates hepatic macrophage recruitment upon injury, which subsequently shapes the inflammatory response in the injured liver, affecting macrophage/DC and Th differentiation. CCR8 deficiency protects the liver against injury, ameliorating initial inflammatory responses and hepatic fibrogenesis. Inhibition of CCR8 or its ligand, CCL1, might represent a successful therapeutic target to limit liver inflammation and fibrosis progression.

Short communication: evidence of HIV type 1 clade C env clones containing low V3 loop charge obtained from an AIDS patient in India that uses CXCR6 and CCR8 for entry in addition to CCR5.

Abstract HIV-1 clade C is the major subtype circulating in India and preferentially uses CCR5 during the entire disease course. We have recently shown that env clones from an Indian patient; NARI-VB105 uses multiple coreceptors for entry and was presented with an unusual V3 loop sequence giving rise to high net V3 loop positive charges. Here we show that env clones belonging to subtype C obtained from an AIDS patient, NARI-VB52, use CXCR6 and CCR8 in addition to CCR5 for entry. However, unlike the NARI-105 patient, the env clones contained a low V3 loop net charge of +3 with a conserved GPGQ motif typical of CCR5 using subtype C strains, indicating that residues outside the V3 loop contributed to extended coreceptor use in this particular patient.

Coreceptor usage by HIV-1 and HIV-2 primary isolates: the relevance of CCR8 chemokine receptor as an alternative coreceptor.

The human immunodeficiency virus replication cycle begins by sequential interactions between viral envelope glycoproteins with CD4 molecule and a member of the seven-transmembrane, G-protein-coupled, receptors' family (coreceptor). In this report we focused on the contribution of CCR8 as alternative coreceptor for HIV-1 and HIV-2 isolates. We found that this coreceptor was efficiently used not only by HIV-2 but particularly by HIV-1 isolates. We demonstrate that CXCR4 usage, either alone or together with CCR5 and/or CCR8, was more frequently observed in HIV-1 than in HIV-2 isolates. Directly related to this is the finding that the non-usage of CXCR4 is significantly more common in HIV-2 isolates; both features could be associated with the slower disease progression generally observed in HIV-2 infected patients. The ability of some viral isolates to use alternative coreceptors besides CCR5 and CXCR4 could further impact on the efficacy of entry inhibitor therapy and possibly also in HIV pathogenesis.