Host absence of CCR5 potentiates dendritic cell vaccination

Single-cell RNA sequencing uncovers heterogeneous transcriptional signatures in tumor-infiltrated dendritic cells in prostate cancer

Prostate cancer (PCa) is one of the two solid malignancies in which a higher T cell infiltration in the tumor microenvironment (TME) corresponds with a worse prognosis for the tumor. The inability of T cells to eliminate tumor cells despite an increase in their number reinforces the possibility of impaired antigen presentation. In this study, we investigated the TME at single-cell resolution to understand the molecular function and communication of dendritic cells (DCs) (as professional antigen-presenting cells). According to our data, tumor cells stimulate the migration of immature DCs to the tumor site by inducing inflammatory chemokines. Many signaling pathways such as TNF-α/NF-κB, IL2/STAT5, and E2F up-regulated after DCs enter the tumor location. In addition, some molecules such as GPR34 and SLCO2B1 decreased on the surface of DCs. The analysis of molecular and signaling alterations in DCs revealed some suppression mechanisms of tumors, such as removing mature DCs, reducing the DC's survival, inducing anergy or exhaustion in the effector T cells, and enhancing the differentiation of T cells to Th2 and T_regs. In addition, we investigated the cellular and molecular communication between DCs and macrophages in the tumor site and found three molecular pairs including CCR5/CCL5, CD52/SIGLEC10, and HLA-DPB1/TNFSF13B. These molecular pairs are involved in the migration of immature DCs to the TME and disrupt the antigen-presenting function of DCs. Furthermore, we presented new therapeutic targets by the construction of a gene co-expression network. These data increase our knowledge of the heterogeneity and the role of DCs in PCa TME.

Evaluating the Association between CCR5delta32 Polymorphism (rs333) and the Risk of Breast Cancer in a Cohort of Iranian Population

Background

CC chemokine receptor 5 (CCR5) is introduced as an immune response modulator. The activity of CCR5 influences breast tumour development in a p53-dependent manner. This study aimed to investigate the frequency of CCR5delta32 and its association with the risk of breast cancer in 1038 blood samples in North East of Iran.

Methods

In this case-control study, we genotyped 570 control samples and 468 breast cancer patients by a gel electrophoresis-based gap-polymerase chain reaction (gap-PCR) method Mashhad, Iran. The data were analyzed using the SPSS software.

Results

Of 570 controls included, 542 (95.09%) had CCR5delta32 ^{wild/wild (W/W)} genotype, 28 samples (4.91%) had CCR5delta32 ^{wild/deletion (W/D)} genotype and none of them were CCR5delta32 ^{deletion/deletion (D/D)} genotype (0%). While 428 samples of patients (91.45%) had CCR5delta32 ^W/W genotype, 40 samples (8.55%) had CCR5delta32 ^W/D and CCR5delta32 ^D/D homozygous was nil (0%) amongst cases. All samples were in the Hardy-Weinberg equilibrium (P>0.05). According to the allele frequency, D allele, as a risky allele, in the cases was more than the control samples (0.0427 vs 0.0245, respectively) (P=0.0206). Hence, W/D genotype may confer a risk effect (OR=1.77, CI: 1.09-2.90; P=0.0206) compared with WW genotype between case and control groups.

Conclusion

There is a statistically significant association between CCR5W/D and breast cancer risk. CCR5 may be regarded as a target for the prevention of breast cancer in certain conditions such as interaction with p53 variants, which remains to be further investigated.

Extended CCR5 Blockade for Graft-versus-Host Disease Prophylaxis Improves Outcomes of Reduced-Intensity Unrelated Donor Hematopoietic Cell Transplantation: A Phase II Clinical Trial

Graft-versus-host disease (GVHD) remains the most common treatment-related complication after allogeneic hematopoietic cell transplantation (allo-HCT). Lymphocyte migration plays a critical role in the pathogenesis of GVHD. A previous phase I/II trial demonstrated that CCR5 blockade with maraviroc in the first 30days after allo-HCT resulted in a low incidence of early acute GVHD, primarily in visceral organs, but with no impact on late acute or chronic GVHD. We conducted a phase II trial to examine the efficacy of an extended course of maraviroc, administered through post-transplantation day +90 in addition to standard prophylaxis in 37 recipients of reduced-intensity-conditioned unrelated donor allo-HCT performed to treat hematologic malignancies. Extended maraviroc treatment was safe and feasible. The primary study endpoint, day +180 rate of grade II-IV acute GVHD, was 22 ± 7%, liver GVHD was not observed, and gut GVHD was uncommon. The day +180 rate of grade III-IV acute GVHD was 5 ± 4%. The 1-year rate of moderate to severe chronic GVHD was 8 ± 5% and that of disease relapse was 30 ± 8%. Overall survival at 1 year was 70 ± 8%. Compared with the previously studied short course of maraviroc, the extended course resulted in a significantly higher GVHD-free, relapse-free survival (adjusted hazard ratio [HR], .45; 95% confidence interval [CI], .25 to .82; P = .009) and overall survival (adjusted HR, .48; 95% CI, .24 to .96; P = .037). A combined analysis of both trials showed that high maraviroc trough concentrations on the day of hematopoietic cell infusion were associated with lower rates of acute GVHD. An extended course of maraviroc after reduced-intensity-conditioned unrelated donor allo-HCT is safe and effective in preventing acute and chronic GVHD and is associated with favorable survival.

Ethyl carbamate: An emerging food and environmental toxicant

Ethyl carbamate (EC), a chemical substance widely present in fermented food products and alcoholic beverages, has been classified as a Group 2A carcinogen by the International Agency for Research on Cancer (IARC). New evidence indicates that long-term exposure to EC may cause neurological disorders. Formation of EC in food and its metabolism have therefore been studied extensively and analytical methods for EC in various food matrices have been established. Due to the potential threat of EC to human health, mitigation strategies for EC in food products by physical, chemical, enzymatic, and genetic engineering methods have been developed. Natural products are suggested to provide protection against EC-induced toxicity through the modulation of oxidative stress. This review summarizes knowledge on the formation and metabolism of EC, detection of EC in food products, toxic effects of EC on various organs, and mitigation strategies including prevention of EC-induced tumorigenesis and genotoxicity by natural products.

CCR5 in recruitment and activation of myeloid-derived suppressor cells in melanoma

Malignant melanoma is characterized by the development of chronic inflammation in the tumor microenvironment, leading to the accumulation of myeloid-derived suppressor cells (MDSCs). Using ret transgenic mouse melanoma model, we found a significant migration of MDSCs expressing C-C chemokine receptor (CCR)5 into primary tumors and metastatic lymph nodes, which was correlated with tumor progression. An increased CCR5 expression on MDSCs was associated with elevated concentrations of CCR5 ligands in melanoma microenvironment. In vitro experiments showed that the upregulation of CCR5 expression on CD11b+Gr1+ immature myeloid cells was induced by CCR5 ligands, IL-6, GM-CSF, and other inflammatory factors. Furthermore, CCR5+ MDSCs infiltrating melanoma lesions displayed a stronger immunosuppressive pattern than their CCR5- counterparts. Targeting CCR5/CCR5 ligand signaling via a fusion protein mCCR5-Ig, which selectively binds and neutralizes all three CCR5 ligands, increased the survival of tumor-bearing mice. This was associated with a reduced migration and immunosuppressive potential of tumor MDSCs. In melanoma patients, circulating CCR5+ MDSCs were increased as compared to healthy donors. Like in melanoma-bearing mice, we observed an enrichment of these cells and CCR5 ligands in tumors as compared to the peripheral blood. Our findings define a critical role for CCR5 not only in the recruitment but also in the activation of MDSCs in tumor lesions, suggesting that novel strategies of melanoma treatment could be based on blocking CCR5/CCR5 ligand interactions.

Possible Impact of 190G > A CCR2 and Δ32 CCR5 Mutations on Decrease of the HBV Vaccine Immunogenicity-A Preliminary Report

Background: Chemokine genetic variations are involved in infectious diseases such as hepatitis B virus (HBV). Several allelic variants might, in theory, affect the outcome of vaccination. Objectives: This study was carried out to examine the associations of Δ32 CCR5 and 190G > A CCR2 polymorphisms with a response to a primary course of three HBV vaccinations. Methods: Between December 2014 and December 2016, patients from three randomly selected primary care clinics in the West Pomeranian region (Poland), 1 month after receiving the third dose of HBV vaccine, were enrolled. Enzyme-linked immunosorbent assay (ELISA) system version 3.0 was used to detect anti-HBs and anti-HBc totals. The identification of polymorphisms were performed by a polymerase chain reaction technique using a single primer extension assay. Genotype distributions of responders versus non-responders to HBV vaccination were compared on the basis of anti-HBs level. Results: In 149 patients (mean age 60 years) the mean anti-HBs level was 652.2 ± 425.9 mIU/mL (range: 0–1111.0 mIU/mL). There were 14.1% (n = 21) non-responders to the HBV vaccine (anti-HBs < 10.0 mIU/mL). The wild type/Δ32 genotype of CCR5 gene was found in 18.1% participants, and 1.3% were Δ32/Δ32 homozygotes. The frequency of allele A of the CCR2 gene was 11.1%. Lower anti-HBs levels in Δ32/Δ32 homozygotes were observed (Me = 61 mIU/mL vs. Me = 660.2 mIU/mL; p = 0.048). As age was found to be a correlate to the anti-HBs titer (r = −0.218, p = 0.0075; 95% CI: −0.366–−0.059)—an analysis of a co-variance was performed which found a statistically significant (p = 0.04) difference in anti-HBs titres between Δ32/Δ32 homozygotes and other CCR5 genotypes. The association between anti-HBs titres and CCR2 genotypes was not statistically significant. Conclusions: Our study—which is a preliminary report that suggest this topic deserves further observation with larger sample sizes, different ethnicities, and other single nucleotide poly-morphisms (SNPs)—suggests the possible involvement of CCR5 polymorphism in impairing the immunologic response to HBV vaccination, predominantly in relation to the passage of time.

CCR5 Polymorphism as a Protective Factor for Hepatocellular Carcinoma in Hepatitis B Virus-Infected Iranian Patients

The CC chemokine receptor 5 (CCR5) delta 32 allele results in a nonfunctional form of the chemokine receptor and has been implicated in a variety of immune-mediated diseases. CCR5Δ32 may also predispose one to chronic liver disease or be linked with resistance to HBV infection. This study was undertaken to investigate any association between CCR5 polymorphism with resistance to hepatitis B or susceptibility to HBV infection. A total of 812 Iranian individuals were enrolled into two groups: HBV infected cases (n=357), who were HBsAg-positive, and healthy controls (n=455). We assessed polymorphisms in the CCR5 gene using specific CCR5 oligonucleotide primers surrounding the breakpoint deletion. Genotype distributions of the HBV infected cases and healthy controls were determined and compared. The CCR5/CCR5 (WW) and CCR5/CCR5Δ32 (W/D) genotypes were found in (98%) and (2%) of HBV infected cases, respectively. The CCR5 Δ32/Δ32genotype was not found in HBV infected cases. Genotype distributions of CCR5 in healthy controls were W/W genotype in (87.3%), W/D genotype in (11.2%) and D/D genotype in (1.5%). Heterozygosity for CCR5/CCR5Δ32 (W/D) in healthy controls was greater than in HBV infected cases (11.2% vs 2%, p < 0.001). W/D and D/D genotypes were more prominent in healthy controls than in HBV infected cases. This study provides evidence that the CCR5Δ32 polymorphism may have a protective effect in resistance to HBV infection at least in the Iranian population.

Downregulation of CCR5 inhibits the proliferation and invasion of cervical cancer cells and is regulated by microRNA-107

Cervical cancer is among the most prevalent forms of cancer worldwide. C-C chemokine receptor type 5 (CCR5) is hypothesized to be a key functional protein involved in tumorigenesis. However, the role of CCR5 in cervical cancer remains unclear. Reverse transcription-quantitative polymerase chain reaction and western blot analysis were used to evaluate the mRNA and protein expression levels of CCR5 in human cervical carcinoma tissues. Furthermore, a small interfering RNA was employed to knockdown CCR5 in HeLa and C33A cells. MTT, colony formation and Transwell assays were performed to determine the effects of this knockdown on cell viability, proliferation and invasion. In addition, micro RNA (miR)-107 was identified as a potential candidate regulator of CCR5 using miR prediction algorithms, and the effects of miR-107 and its antisense miR on CCR5 mRNA expression were determined. The results of the present study indicated that CCR5 is overexpressed in human cervical cancer tissues compared with adjacent normal tissues, and its downregulation inhibits cervical cancer cell growth and proliferation. Furthermore, the downregulation of CCR5 appears to suppress cervical cancer cell invasion. Finally, the tumor suppressor miR-107 was able to directly target CCR5 and inhibit its expression. These results suggest that the upregulation of CCR5, which is inhibited by miR-107, may play a carcinogenic role in cervical cancer and could provide a novel therapeutic target in the future.

B-1 cells promote immunosurveillance against murine melanoma in host absence of CCR5: new perspective in autologous vaccination therapy

Autologous vaccination with tumor-primed dendritic cells increases immune response against tumor, which seems to be improved in host absence of CCR5. Because B-1 lymphocytes modulate the activity of different immune cells, we decided to study their influence in the resistance against murine B16F10 melanoma in a CCR5 deprived environment. Adoptive transfer of peritoneal B-1 CCR5(+/+) lymphocytes to CCR5(-/-) animals inhibited the establishment of lung metastasis and melanoma cell growth, in comparison to saline-treated CCR5(-/-) mice. In loco cell analysis demonstrated that the adoptive transfer of B-1 CCR5(+/+) lymphocytes to CCR5 deficient host was associated with a more intense influx of T CD8(+) to tumor site, indicating that the presence of CCR5(+/+) B-1 cells in the tumor environment induces the migration of T CD8 CCR5(-/-) cells to the implantation site. To corroborate this idea, CCR5(-/-) mice were injected with non B-1 peritoneal cells from wild type (WT) mice before B16F10 inoculation. In this regimen, CCR5(-/-) mice were not protected from tumor growth reinforcing the idea that, in host absence of CCR5, B-1 cells are essential to confer tumor resistance. This work indicates that, in the host absence of CCR5, naive B-1 cells may activate CD8T lymphocytes thereby promoting tumor resistance. Our results strongly suggest that autologous vaccination with B-1 lymphocytes in combination with CCR5 antagonists can be an alternative approach to tumor therapy.

Gene therapy with beta-defensin 2 induces antitumor immunity and enhances local antitumor effects

Beta-defensins, small antimicrobial peptides, are involved in host immune responses to tumors. In this study, we used beta-defensin 2 (BD2) to explore the possible role of beta-defensins in cancer gene therapy. A recombinant plasmid expressing a secretable form of BD2 was constructed. The biological activities of BD2 in immature dendritic cells (iDCs) were tested in vitro and in vivo. The antitumor effects were investigated in three established tumor models. The secreted BD2 was detected and exhibited chemotactic activity in iDCs both in vitro and in vivo. Recruitment and activation of iDCs in tumor niches resulted in significant tumor growth inhibition. Adoptive transfer of splenocytes and depletion of immune cell subsets revealed that CD8(+) T lymphocyte responses mediated the increased tumor inhibition. Furthermore, we also found that chemotactic and maturation-inducing activities in iDCs in tumor milieu contributed to enhanced local antitumor effects. Our study indicates that gene therapy with BD2 can mediate specific antitumor immunity and augment local antitumor effects. Our study also suggested that beta-defensins may merit further exploration for cancer immunotherapy as promising immunogenes.

Role of chemokines and chemokine receptors in shaping the effector phase of the antitumor immune response

Immune system-mediated eradication of neoplastic cells requires induction of a strong long-lasting antitumor T-cell response. However, generation of tumor-specific effector T cells does not necessarily result in tumor clearance. CTL must first be able to migrate to the tumor site, infiltrate the tumor tissue, and interact with the target to finally trigger effector functions indispensable for tumor destruction. Chemokines are involved in circulation, homing, retention, and activation of immunocompetent cells. Although some of them are known to contribute to tumor growth and metastasis, others are responsible for changes in the tumor microenvironment that lead to extensive infiltration of lymphocytes, resulting in tumor eradication. Given their chemoattractive and activating properties, a role for chemokines in the development of the effector phase of the antitumor immune response has been suggested. Here, we emphasize the role of the chemokine-chemokine receptor network at multiple levels of the T-cell-mediated antitumor immune response. The identification of chemokine-dependent molecular mechanisms implicated in tumor-specific CTL trafficking, retention, and regulation of their in situ effector functions may offer new perspectives for development of innovative immunotherapeutic approaches to cancer treatment.

Tumor-infiltrating monocytic myeloid-derived suppressor cells mediate CCR5-dependent recruitment of regulatory T cells favoring tumor growth

Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population of myeloid cells in cancer patients and tumor-bearing mice that potently inhibits T cell responses. During tumor progression, MDSCs accumulate in several organs, including the tumor tissue. So far, tumor-infiltrating MDSC subpopulations remain poorly explored. In this study, we performed global gene expression profiling of mouse tumor-infiltrating granulocytic and monocytic (MO-MDSC) subsets compared with MDSCs from peripheral blood. RMA-S lymphoma-infiltrating MO-MDSCs not only produced high levels of NO and arginase-1, but also greatly increased levels of chemokines comprising the CCR5 ligands CCL3, CCL4, and CCL5. MO-MDSCs isolated from B16 melanoma and from skin tumor-bearing ret transgenic mice also expressed high levels of CCL3, CCL4, and CCL5. Expression of CCR5 was preferentially detected on regulatory T cells (Tregs). Accordingly, tumor-infiltrating MO-MDSCs directly attracted high numbers of Tregs via CCR5 in vitro. Intratumoral injection of CCL4 or CCL5 increased tumor-infiltrating Tregs, and deficiency of CCR5 led to their profound decrease. Moreover, in CCR5-deficient mice, RMA-S and B16 tumor growth was delayed emphasizing the importance of CCR5 in the control of antitumor immune responses. Overall, our data demonstrate that chemokines secreted by tumor-infiltrating MO-MDSCs recruit high numbers of Tregs revealing a novel suppressive role of MDSCs with potential clinical implications for the development of cancer immunotherapies.

Deficiency of C-C chemokine receptor 5 suppresses tumor development via inactivation of NF-κB and upregulation of IL-1Ra in melanoma model

To evaluate the relevance of C-C chemokine receptor type 5 (CCR5) expression and tumor development, we compared melanoma growth in CCR5 knockout (CCR5^−/−) mice and wild type (CCR5^+/+) mice. CCR5^−/− mice showed reduced tumor volume, tumor weight, and increased survival rate when compared to CCR5^+/+ mice. We investigated the activation of NF-κB since it is an implicated transcription factor in the regulation of genes involving cell growth, apoptosis, and tumor growth. Significant inhibition of DNA binding activity of NF-κB, and translocation of p50 and p65 into the nucleus through the inhibition of phosphorylation of IκB was found in the melanoma tissues of CCR5^−/− mice compared to melanoma tissues of CCR5^+/+ mice. NF-κB target apoptotic protein expression, such as cleaved caspase-3, cleaved PARP, and Bax, was elevated, whereas the survival protein expression levels, such as Bcl-2, C-IAP1, was decreased in the melanoma tissues of CCR5^−/− mice. Interestingly, we found that the level of IL-1Ra, a tumor growth suppressive cytokine, was significantly elevated in tumor tissue and spleen of CCR5^−/− mice compared to the level in CCR5^+/+ mice. Moreover, infiltration of CD8⁺ cytotoxic T cell and CD57⁺ natural killer cells was significantly increased in melanoma tumor and spleen tissue of CCR5^−/− mice compared to that of CCR5^+/+ mice. Therefore, these results showed that CCR5 deficiency caused apoptotic cell death of melanoma through inhibition of NF-κB and upregulation of IL-1Ra.

The immunosuppressive tumor environment is the major impediment to successful therapeutic vaccination in Neu transgenic mice

We earlier showed that therapeutic vaccination of FVB/N mice with alphaviral replicon particles expressing rat neuET-VRP induced regression of established neu-expressing tumors. In this study, we evaluated the efficacy of neuET-VRPs in a tolerant mouse model using mice with transgenic expression of neu. Using the same approach that induced regression of 70 mm(2) tumors in FVB/N mice, we were unable to inhibit tumor growth in tolerant neu-N mice, despite showing neu-specific B-cell and T-cell responses post vaccination. As neu-N mice have a limited T-cell repertoire specific to neu, we hypothesized that the absence of these T cells led to differences in the vaccine response. However, transfer of neu-specific T cells from vaccinated FVB/N mice was not effective in inducing tumor regression, as these cells did not proliferate in the tumor-draining lymph node. Vaccination given with low-dose cyclophosphamide to deplete regulatory T cells delayed tumor growth but did not result in tumor regression. Finally, we showed that T cells given with vaccination were effective in inhibiting tumor growth, if administered with approaches to deplete myeloid-derived suppressor cells. Our data show that both central deletion of lymphocytes and peripheral immunosuppressive mechanisms are present in neu-N mice. However, the major impediment to successful vaccination is the peripheral tumor-induced immune suppression.

Disruption of CCR5-dependent homing of regulatory T cells inhibits tumor growth in a murine model of pancreatic cancer

Tumors evade immune destruction by actively inducing immune tolerance through the recruitment of CD4(+)CD25(+)Foxp3(+) regulatory T cells (Treg). We have previously described increased prevalence of these cells in pancreatic adenocarcinoma, but it remains unclear what mechanisms are involved in recruiting Tregs into the tumor microenvironment. Here, we postulated that chemokines might direct Treg homing to tumor. We show, in both human pancreatic adenocarcinoma and a murine pancreatic tumor model (Pan02), that tumor cells produce increased levels of ligands for the CCR5 chemokine receptor and, reciprocally, that CD4(+) Foxp3(+) Tregs, compared with CD4(+) Foxp3(-) effector T cells, preferentially express CCR5. When CCR5/CCL5 signaling is disrupted, either by reducing CCL5 production by tumor cells or by systemic administration of a CCR5 inhibitor (N,N-dimethyl-N-{{4-{[2-(4-methylphenyl)-6,7-dihydro-5H-benzocyclohepten-8-yl]carbonyl}amino}}benzyl]-N,N-dimethyl-N- {{{4-{{{[2-(4-methylphenyl)-6,7-dihydro-5H-benzocycloheptan-8-yl]carbonyl}amino}}benzyl}}}tetrahydro-2H-pyran-4-aminiumchloride; TAK-779), Treg migration to tumors is reduced and tumors are smaller than in control mice. Thus, this study demonstrates the importance of Tregs in immune evasion by tumors, how blockade of Treg migration might inhibit tumor growth, and, specifically in pancreatic adenocarcinoma, the role of CCR5 in the homing of tumor-associated Tregs. Selective targeting of CCR5/CCL5 signaling may represent a novel immunomodulatory strategy for the treatment of cancer.

Alphaviral vector-transduced dendritic cells are successful therapeutic vaccines against neu-overexpressing tumors in wild-type mice

While dendritic cell (DC) vaccines can protect hosts from tumor challenge, their ability to effectively inhibit the growth of established tumors remains indeterminate. Previously, we have shown that human DCs transduced with Venezuelan equine encephalitis virus replicon particles (VRPs) were potent stimulators of antigen-specific T cells in vitro. Therefore, we investigated the ability of VRP-transduced DCs (VRP-DCs) to induce therapeutic immunity in vivo against tumors overexpressing the neu oncoprotein. Transduction of murine DCs with VRPs resulted in high-level transgene expression, DC maturation and secretion of proinflammatory cytokines. Vaccination with VRP-DCs expressing a truncated neu oncoprotein induced robust neu-specific CD8(+) T cell and anti-neu IgG responses. Furthermore, a single vaccination with VRP-DCs induced the regression of large established tumors in wild-type mice. Interestingly, depletion of CD4(+), but not CD8(+), T cells completely abrogated inhibition of tumor growth following vaccination. Taken together, our results demonstrate that VRP-DC vaccines induce potent immunity against established tumors, and emphasize the importance of the generation of both CD4(+) T cell and B cell responses for efficient tumor inhibition. These findings provide the rationale for future evaluation of VRP-DC vaccines in the clinical setting.

Profiles of chemokine receptors in melanocytic lesions: de novo expression of CXCR6 in melanoma

Selective expression of certain chemokine receptors by melanoma cells and the presence of their ligands in tissues might govern organ site-specific metastasis. Because the expression profile of chemokine receptors in tissues of melanocytic origin is unknown, we performed a comprehensive study on melanocytic tissue samples investigating the expression of 18 chemokine receptors at the mRNA level by real-time polymerase chain reaction, using a semiquantitative approach, and of 3 chemokine receptors (CXCR6, CCR9, and XCR1) at the protein level. We report on the de novo expression of CXCR6 in primary melanomas and melanoma metastases, but absence in melanoma cell lines and congenital nevi. CXCR4 and CCR1 were the only 2 chemokine receptors that were consistently expressed in melanocytes, melanoma cell lines, primary, and metastatic melanoma; CCR1 expression increased significantly over progression. CCR9 and XCR1 transcripts were found in melanocytic lesions, and expression was confirmed by immunohistochemistry. Transcripts for CCR10 were not found in any of the lesions, but in some melanoma cell lines. Expression of CCR7 was observed in primary melanomas and some metastases. CCR5 was exclusively expressed in primary melanomas and some cutaneous metastases. Results revealed a restricted and differential pattern of chemokine receptor expression in melanoma tissue, which varies substantially from the expression profile of melanoma cell lines and warrants functional studies on some receptors.

Clinical utilization of chemokines to combat cancer: the double-edged sword

Chemokines are a small group of related chemo-attractant peptides that play an essential role in the homeostatic maintenance of the immune system. They control the recruitment of cells needed for the induction and activation of innate and adaptive immune responses. However, tumors also utilize chemokines to actively progress and evade immunosurveillance. In fact, chemokines are involved directly or indirectly in almost every aspect of tumorigenesis. They mediate survival and metastatic spread of tumors, promote new blood vessel formation (neovascularization) and induce an immunosuppressive microenvironment via recruitment of immunosuppressive cells. As a result, a number of therapeutic strategies have been proposed to target almost every step of the chemokine/chemokine receptor involvement in tumors. Yet, despite occasional success stories, most of them appear to be ineffective or impractical, presumably due to 'nonspecific' harm of cells needed for the elimination of tumor escapees and maintenance of immunological memory. The strategy would only be effective if it also promoted antitumor adaptive immune responses capable of combating a residual disease and tumor relapse.

Genetic protection against hepatitis B virus conferred by CCR5Delta32: Evidence that CCR5 contributes to viral persistence

Recovery from acute hepatitis B virus (HBV) infection requires a broad, vigorous T-cell response, which is enhanced in mice when chemokine receptor 5 (CCR5) is missing. To test the hypothesis that production of a nonfunctional CCR5 (CCR5Delta32 [a functionally null allele containing a 32-bp deletion]) increases the likelihood of recovery from hepatitis B in humans, we studied 526 persons from three cohorts in which one person with HBV persistence was matched to two persons who recovered from an HBV infection. Recovery or persistence was determined prior to availability of lamivudine. We determined genotypes for CCR5Delta32 and for polymorphisms in the CCR5 promoter and in coding regions of the neighboring genes, chemokine receptor 2 (CCR2) and chemokine receptor-like 2 (CCRL2). Allele and haplotype frequencies were compared among the 190 persons with viral recovery and the 336 with persistence by use of conditional logistic regression. CCR5Delta32 reduced the risk of developing a persistent HBV infection by nearly half (odds ratio [OR], 0.53; 95% confidence interval [CI], 0.33 to 0.83; P = 0.006). This association was virtually identical in persons with and without a concomitant human immunodeficiency virus infection. Of the nine individuals who were homozygous for the deletion, eight recovered from infection (OR, 0.25; 95% CI, 0.03 to 1.99; P = 0.19). None of the other neighboring polymorphisms examined were associated with HBV outcome. These data demonstrate a protective effect of CCR5Delta32 in recovery from an HBV infection, provide genetic epidemiological evidence for a role of CCR5 in the immune response to HBV, and suggest a potential therapeutic treatment for patients persistently infected with HBV.

Critical role for CCR5 in the function of donor CD4+CD25+ regulatory T cells during acute graft-versus-host disease

CD4+CD25+ regulatory T cells (T(regs)) have been shown to inhibit graft-versus-host disease (GVHD) in murine models, and this suppression was mediated by T(regs) expressing the lymphoid homing molecule l-selectin. Here, we demonstrate that T(regs) lacking expression of the chemokine receptor CCR5 were far less effective in preventing lethality from GVHD. Survival of irradiated recipient animals given transplants supplemented with CCR5-/- T(regs) was significantly decreased, and GVHD scores were enhanced compared with animals receiving wild-type (WT) T(regs). CCR5-/- T(regs) were functional in suppressing T-cell proliferation in vitro and ex vivo. However, although the accumulation of T(regs) within lymphoid tissues during the first week after transplantation was not dependent on CCR5, the lack of function of CCR5-/- T(regs) correlated with impaired accumulation of these cells in the liver, lung, spleen, and mesenteric lymph node, more than one week after transplantation. These data are the first to definitively demonstrate a requirement for CCR5 in T(reg) function, and indicate that in addition to their previously defined role in inhibiting effector T-cell expansion in lymphoid tissues during GVHD, later recruitment of T(regs) to both lymphoid tissues and GVHD target organs is important in their ability to prolong survival after allogeneic bone marrow transplantation.

C-C chemokine receptor 5 on stromal cells promotes pulmonary metastasis

We have shown that mice that express the C-C chemokine receptor 5 (CCR5) have enhanced local tumor growth and an impaired response to vaccine therapy compared with CCR5 knockout (CCR5(-/-)) mice. Here, we extend these observations to evaluate the function of CCR5 in pulmonary metastasis and the mechanism underlying the diminished tumor growth in CCR5(-/-) mice. Lung metastases were counted in wild-type (WT) and CCR5(-/-) mice following the injection of 1 x 10(6) B16-F10 melanoma cells. These results were compared with those from syngeneic bone marrow chimeric mice formed by the transfer of WT bone marrow into irradiated CCR5(-/-) and CCR5(-/-) marrow into irradiated WT mice. Intact CCR5(-/-) mice developed fewer metastases than WT mice (40.2 versus 70.6; P < 0.05). Bone marrow chimeras formed by the transfer of WT bone marrow into CCR5(-/-) hosts had fewer metastases than WT hosts injected with knockout marrow (46.6 versus 98.6; P < 0.01). Adoptive transfer of CCR5-expressing leukocytes also failed to promote metastasis in CCR5(-/-) mice. However, the i.v. transfer of WT pulmonary stromal cells into CCR5(-/-) mice increased the number of metastases compared with transfer of CCR5(-/-) stromal cells (102.8 versus 26.0; P < 0.05). These results show for the first time that CCR5 expression on stromal and not hematopoietic cells contributes to tumor metastasis. Therefore, recently developed CCR5 inhibitors may have a novel benefit in cancer therapy.

Donor T-cell production of RANTES significantly contributes to the development of idiopathic pneumonia syndrome after allogeneic stem cell transplantation

Idiopathic pneumonia syndrome (IPS) is a major cause of mortality following allogeneic stem cell transplantation (allo-SCT). Clinical and experimental data support a role for conditioning-induced inflammation and alloreactive T-cell responses in IPS pathophysiology, but the mechanisms by which donor leukocytes are ultimately recruited to the lung are not fully understood. RANTES is a chemokine ligand that is up-regulated during inflammation and promotes the recruitment of T cells and macrophages to sites of tissue damage. Using a lethally irradiated murine SCT model (B6 --> B6D2F1), we evaluated the role of donor leukocyte-derived RANTES in the development of IPS. Pulmonary mRNA and protein levels of RANTES were significantly elevated in allo-SCT recipients compared to syngeneic controls and were associated with enhanced mRNA expression of CCR5 and CCR1 and with inflammatory cell infiltration into the lung. Allo-SCT with RANTES-/- donor cells significantly decreased IPS and improved survival. Combinations of allogeneic wild-type or RANTES-/- bone marrow with wild-type or RANTES-/- T cells demonstrated that the expression of RANTES by donor T cells was critical to the development of lung injury after SCT. These data reveal that donor T cells can help regulate leukocyte recruitment to the lung after allo-SCT and provide a possible mechanism through which inflammation engendered by SCT conditioning regimens is linked to allo-specific T-cell responses during the development of IPS.

An absence of CCR5 on donor cells results in acceleration of acute graft-vs-host disease

OBJECTIVE

Chemokines have been postulated to play a role in the pathogenesis of graft-vs-host disease (GVHD) after allogeneic hematopoietic transplantation. Recent reports have indicated that the absence of donor expression of CCR5 on T cells ameliorates GVHD in models using no conditioning of the recipient. We therefore assessed the role of CCR5 on donor cells in models where intensive conditioning of the recipient occurs, thus more appropriately mirroring the clinical experience.

METHODS

Lethally irradiated mice received allogeneic bone marrow transplants. Recipients were given full MHC-mismatched donor bone marrow and splenocytes from CCR5 knockout (KO) mice vs wild-type (WT) control donors.

RESULTS

Recipients of CCR5 KO donor cells succumbed to acute GVHD at an accelerated rate compared to mice receiving WT cells. Donor CD8+ T cells expanded to a significantly greater extent in recipients of CCR5 KO vs WT control cells. T cells recovered from recipients of CCR5 KO cells produced more IFN-gamma and TNF-alpha and proliferated to a T-cell mitogen at a significantly greater level then T cells from recipients of WT cells, indicating that CCR5 plays a role in downregulating donor alloreactive CD8+ T-cell expansion. Histological assessment of the mice indicated pathological lesions in the kidneys and a greater degree of liver pathological changes in mice that received CCR5 KO donor grafts.

CONCLUSIONS

These results indicate that the role of CCR5 in allogeneic bone marrow transplants and GVHD is more complex than initially thought. In a murine transplant model with intensive conditioning, the overall effect of absent CCR5 expression on donor cells results in greater GVHD and donor T-cell expansion.