Regulatory T Cells Exhibit Distinct Features in Human Breast Cancer.

Regulatory T (Treg) cells reside in lymphoid organs and barrier tissues where they control different types of inflammatory responses. Treg cells are also found in human cancers, and studies in animal models suggest that they contribute to cancer progression. However, properties of human intratumoral Treg cells and those present in corresponding normal tissue remain largely unknown. Here, we analyzed features of Treg cells in untreated human breast carcinomas, normal mammary gland, and peripheral blood. Tumor-resident Treg cells were potently suppressive and their gene-expression pattern resembled that of normal breast tissue, but not of activated peripheral blood Treg cells. Nevertheless, a number of cytokine and chemokine receptor genes, most notably CCR8, were upregulated in tumor-resident Treg cells in comparison to normal tissue-resident ones. Our studies suggest that targeting CCR8 for the depletion of tumor-resident Treg cells might represent a promising immunotherapeutic approach for the treatment of breast cancer.

CCR8 regulates contact hypersensitivity by restricting cutaneous dendritic cell migration to the draining lymph nodes.

Allergic contact dermatitis (ACD) is a typical occupational disease in industrialized countries. Although various cytokines and chemokines are suggested to be involved in the pathogenesis of ACD, the roles of these molecules remain to be elucidated. CC chemokine receptor 8 (CCR8) is one such molecule, of which expression is up-regulated in inflammatory sites of ACD patients. In this study, we found that Ccr8(-/-) mice developed severer contact hypersensitivity (CHS) responses to 2,4-dinitrofluorobenzene, a murine model of ACD, compared with wild-type mice. T cells from Ccr8(-/-) mice showed enhanced proliferative recall responses and Th1 and Th17 cell populations were expanded in these mice. However, CHS responses were similar between SCID mice adoptively transferred with Ccr8(-/-) and wild-type T cells, suggesting that CCR8 in T cells is not responsible for the exacerbation of CHS. Notably, skin-resident dendritic cells (DCs), such as Langerhans cells and dermal DCs, and inflammatory DCs were highly accumulated in lymph nodes (LNs) of Ccr8(-/-) mice after sensitization. Consistent with this, Ccr8(-/-) antigen-presenting cells readily migrated from the skin to the draining LNs after sensitization. These observations suggest that CCR8 negatively regulates migration of cutaneous DCs from the skin to the draining LNs in CHS by keeping these cells in the skin.

Antagonism of chemokine receptor CCR8 is ineffective in a primate model of asthma.

BACKGROUND: Expression of the T-cell-associated chemokine receptor CCR8 and its ligand CCL1 have been demonstrated to be elevated in patients with asthma. CCR8 deficiency or inhibition in models of allergic airway disease in mice resulted in conflicting data. OBJECTIVE: To investigate the effects of a selective small molecule CCR8 inhibitor (ML604086) in a primate model of asthma. METHODS: ML604086 and vehicle were administered by intravenous infusion to 12 cynomolgus monkeys during airway challenge with Ascaris suum. Samples were collected throughout the study to measure pharmacokinetics (PK) and systemic CCR8 inhibition, as well as inflammation, T helper 2 (Th2) cytokines and mucus in bronchoalveolar lavage (BAL). Airway resistance and compliance were measured before and after allergen challenge, and in response to increasing concentrations of methacholine. RESULTS: ML604086 inhibited CCL1 binding to CCR8 on circulating T-cells>98% throughout the duration of the study. However, CCR8 inhibition had no significant effect on allergen-induced BAL eosinophilia and the induction of the Th2 cytokines IL-4, IL-5, IL-13 and mucus levels in BAL. Changes in airway resistance and compliance induced by allergen provocation and increasing concentrations of methacholine were also not affected by ML604086. CONCLUSIONS: These results clearly demonstrate a dispensable role for CCR8 in ameliorating allergic airway disease in atopic primates, and suggest that strategies other than CCR8 antagonism should be considered for the treatment of asthma.

Orally bioavailable allosteric CCR8 antagonists inhibit dendritic cell, T cell and eosinophil migration.

The chemokine receptor CCR8 is associated with asthma. Herein, we describe that both mature and immature dendritic cells (DC) express CCR8, whereas only mature DC migrate towards CCL1. Moreover, transient LPS challenge significantly down-regulates CCR8 expression hence attenuating CCL1 chemotaxis. To inhibit CCR8 pathophysiology, we recently developed a novel series of small molecule CCR8 antagonists containing a diazaspiroundecane scaffold, which had micromolar potency. However, these first generation antagonists had high lipophilicity that endowed the compounds with poor physicochemical properties, and were thus not suitable for further development. By introducing polar bicyclic groups on the N-benzyl substituent and building in further polar interactions on the amide group we now show second generation diazospiroundecane antagonists with significantly improved overall properties. Potency is substantially improved from micromolar to nanomolar potency in CCR8 binding and inhibition of chemotaxis in human primary T cells, DC and in an eosinophil cell line. In addition to high potency, the most attractive antagonist, AZ084 showed excellent selectivity, high metabolic stability in vitro and an attractive in vivo PK profile with a long half-life in rat. Interestingly, in ligand saturation experiments and in wash-off experiments, CCL1 was shown to have two binding sites to CCR8 with K(d) at 1.2/68pM respectively, and on-off rates of 0.004 and 0.0035/0.02pMmin, respectively. The lead antagonist, AZ084, appears to act as an allosteric inhibitor with a K(i) at 0.9nM. Taken together, we herein report a novel oral allosteric CCR8 antagonist with predicted low once-daily dosing capable of potent inhibition of both human T cell and DC functions.

Expression of CCR8 is increased in asthma.

BACKGROUND: Chemokines and their receptors could play key roles in the recruitment of T cells to the asthmatic lung. CCR8 is preferentially expressed on T-helper type 2 cells, and is thought to play a role in the pathogenesis of human asthma. OBJECTIVE: Determine the expression of CCR8 on T cells in blood, bronchoalveolar lavage (BAL) and bronchial mucosa from asthmatics and normal subjects. METHODS: CCR8 expression in blood and BAL from asthma and normal subjects was studied using flow cytometry. CCR8 expression on IFN-gamma+ and IL-4+/IL-13+ blood and BAL T cells was studied following stimulation with Phorbol-Myristate-Acetate and Calcium Ionophore. Paraffin-embedded bronchial biopsies were used to study CCR8 in bronchial epithelium. RESULTS: The percentage of CD3+ cells expressing CCR8 in the blood was higher in asthmatics (4.7+/-0.4%) compared with normal subjects (3.0+/-0.4%; P<0.01). There was an approximately sixfold enrichment of CCR8 on IL-4+/IL-13+ cells compared with IFN-gamma+ T cells (P<0.001) in both asthmatic and normal subjects in both blood and BAL. Significantly more BAL T cells expressed CCR8 in asthmatic (8.6+/-0.8%) compared with normal subjects (3.9+/-0.7%) (P<0.01). In paired blood-BAL samples from asthmatics, significantly more CCR8+CD3+ T cells were present in BAL (9.0+/-0.9%) than in blood (5.6+/-0.9%; P<0.05). There were more CCR8-positive cells in bronchial biopsies from asthmatic (93+/-11 cells/mm2) compared with normal subjects (30+/-16 cells/mm2) (P<0.05). The ligand CCL1 was increased in the BAL of asthmatics compared with normal subjects (35+/-6 vs. 12.9+/-7 pg/mL; P<0.05). CONCLUSION: There may be a role for CCR8 in the recruitment of T cells to the lung in asthmatics.