T regulatory cells (Treg) avert autoimmunity, but their increased levels in melanoma confer a poor prognosis. To explore the basis for Treg accumulation in melanoma, we evaluated chemokine expression in patients. A 5-fold increase was documented in the Treg chemoattractants CCL22 and CCL1 in melanoma-affected skin versus unaffected skin, as accompanied by infiltrating FoxP3+ T cells. In parallel, there was an approximately two-fold enhancement in expression of CCR4 in circulating Treg but not T effector cells. We hypothesized that redirecting Treg away from tumors might suppress autoimmune side effects caused by immune checkpoint therapeutics now used widely in the clinic. In assessing this hypothesis, we observed a marked increase in skin Treg in mice vaccinated with Ccl22, with repetitive vaccination sufficient to limit Treg accumulation and melanoma growth in the lungs of animals challenged by tumor cell injection, whether using a prevention or treatment protocol design. The observed change in Treg accumulation in this setting could not be explained by Treg conversion. Overall, our findings offered a preclinical proof of concept for the potential use of CCL22 delivered by local injection as a strategy to enhance the efficacious response to immune checkpoint therapy while suppressing its autoimmune side effects. Cancer Res; 76(21); 6230-40. ©2016 AACR.

BACKGROUND

Asthma is characterized by chronic inflammation of the airways with significant changes in leucocyte trafficking, cellular activation and tissue remodelling. Brain-derived neurotrophic factor (BDNF) has been involved with asthma and allergic diseases but its role as a severity marker in paediatric asthma has not been clinically assessed.

OBJECTIVE

To evaluate plasma BDNF and inflammatory markers in order to address their relationships with disease severity in children (6-15 years) with controlled persistent asthma.

METHODS

Children with persistent asthma were selected and lung function and skin prick tests were performed in all patients. Plasma BDNF levels and various inflammatory markers (CCL3, CCL11, CCL22, CCL24, CXCL8, CXCL9, CXCL10, soluble TNF receptors) were assessed by ELISAs.

RESULTS

Subjects with moderate and severe asthma had higher BDNF levels than mild asthma and controls (P<0.001). The chemokines studied and soluble TNF receptors did not differ between the studied groups.

CONCLUSIONS

Our results indicate BDNF as a potential biomarker for clinical severity in children with asthma.

CC Chemokine ligand 22 (Ccl22) is a selective, high affinity ligand at the CC chemokine receptor 4 (Ccr4). We have identified cDNAs encoding both ligand and receptor of the Ccl22-Ccr4 pair in cDNA libraries of the anterior hypothalamus/pre-optic area (AH/POA) by PCR. The AH/POA is the key brain region where endogenous pyrogens have been shown to act on warm sensitive neurons to affect thermogenesis in brown adipose tissue (BAT) and other thermogenically responsive tissues. We show that functional Ccr4 receptors are present in the AH/POA neurons as injection of Ccl22 into the POA but not to other hypothalamic nuclei induces an increase in core body temperature as measured by radiotelemetry. Indomethacin (5 mg/kg s.c) pre-treatment markedly reduced the hyperthermia evoked by POA injection of Ccl22 (10 ng/0.5 ul) and thus suggests that this hyperthermia is mediated through cyclooxygenase activation and thus likely through the formation and action of the pyrogen prostaglandin E2. The temperature elevation involves a decrease in the respiratory exchange ratio and increased activation of the brown adipose tissue as demonstrated by ¹⁸F-FDG-PET imaging. We describe a novel role to the ligand Ccl22 and its receptor Ccr4 in the anterior hypothalamus in temperature regulation that depends on the synthesis of the endogenous pyrogen, prostaglandin E2.

Ribavirin has proven to be a key component of hepatitis C therapies both involving IFNs and new direct-acting antivirals. The hepatitis C virus-mediated interference with intrahepatic immunity by cleavage of mitochondrial antiviral signaling protein (MAVS) and T cell protein tyrosine phosphatase (TCPTP) suggests an avenue for compounds that may counteract these effects. We therefore studied the effects of ribavirin, with or without inhibition of the nonstructural (NS)3/4A protease, on intrahepatic immunity. The intrahepatic immunity of wild-type and NS3/4A-transgenic mice was determined by Western blot, ELISA, flow cytometry, and survival analysis. Various MAVS or TCPTP constructs were injected hydrodynamically to study their relevance. Ribavirin pretreatment was performed in mice expressing a functional or inhibited NS3/4A protease to analyze its effect on NS3/4A-mediated changes. Intrahepatic NS3/4A expression made mice resistant to TNF-α-induced liver damage and caused an alteration of the intrahepatic cytokine (IFN-γ and IL-10) and chemokine (CCL3, CCL17, CCL22, CXCL9, and CXCL11) profiles toward an anti-inflammatory state. Consistent with this, the number of intrahepatic Th1 cells and IFN-γ(+) T cells in NS3/4A-transgenic mice decreased, whereas the amount of Th2 cells increased. These effects could be reversed by injection of uncleavable TCPTP but not uncleavable MAVS and were absent in a mouse expressing a nonfunctional NS3/4A protease. Importantly, the NS3/4A-mediated effects were reversed by ribavirin treatment. Thus, cleavage of TCPTP by NS3/4A induces a shift of the intrahepatic immune response toward a nonantiviral Th2-dominated immunity. These effects are reversed by ribavirin, supporting that ribavirin complements the effects of direct-acting antivirals as an immunomodulatory compound.

In tumor microenvironment, macrophages as a polarized M2 population promote tumor progression via releasing multiple cytokines and chemokines. A brown seaweed fucose-rich polysaccharide, fucoidan has antitumor activity and immune modulation through affecting tumor cells and lymphocytes. Here, we focused on the effect of fucoidan on macrophages especially M2 subtype. Our results demonstrated that fucoidan down-regulated partial cytokines and chemokines, especially a M2-type chemokine CCL22. Furthermore, fucoidan inhibited tumor cells migration and CD4+ T lymphocytes, especially Treg cells, recruitment induced by M2 macrophages conditioned medium through suppression of CCL22. Mechanismly, fucoidan inhibited CCL22 via suppressing p65-NF-κB phosphorylation and nuclear translocation. In addition, p38-MAPK and PI3K-AKT also affected the expression of CCL22 through differential modulation of NF-κB transcriptional activity. Taken together, we reveal an interesting result that fucoidan can inhibit tumor cell migration and lymphocytes recruitment by suppressing CCL22 in M2 macrophages via NF-κB-dependent transcription, which may be a novel and promising mechanism for tumor immunotherapy.

The expression of chemokines is critical in leukocyte recruitment and inflammation, but the regulatory mechanisms involved remain incompletely defined. While endocrine disrupter chemicals (EDCs) are known to be ubiquitous in the environment and often associated with altered inflammatory response, their potential impact on chemokine expression in monocytes is at present unknown. To this end, the effects of EDCs on the expression of Th1- and Th2-related chemokines in a human monocytic cell line, THP-1, were investigated. THP-1 cells were pre-treated with varying concentrations of EDCs (nonylphenol and 4-octylphenol) with or without the addition of an estrogen receptor (ER) antagonist, ICI 182,780 and then stimulated by lipopolysaccharide (LPS). The levels of chemokines, CXCL10/ IFN-alpha-inducible protein 10 (IP-10, a Th1 chemokine) and monocyte-derived chemokine (MDC)/CCL22, a Th2 chemokine) were measured by ELISA. EDC-mediated signaling events and histone modifications were examined by the use of Western blotting and chromatin immunoprecipitation (ChIP) assay. Nonylphenol and 4-octylphenol were able to suppress LPS-induced MDC and IP-10 expression. This suppressive effect was not reversed by the addition of ICI 182,780. Nonylphenol and 4-octylphenol reduced LPS-induced activation of MAPK signaling pathway, MKK1/2 and ERK, concomitant with decreased levels of LPS-induced acetylated histone 4 (H4) at the IP-10 and MDC gene loci. Nonylphenol and 4-octylphenol suppressed LPS-induced MDC expression in monocytes via, at least in part, the MKK1/2-ERK MAPK pathway and histone H4 acetylation, but not the estrogen receptor.

CC chemokine ligand 17 (CCL17/thymus and activation-regulated chemokine: TARC) and CCL22 (macrophage-derived chemokine: MDC) selectively bind to CC chemokine receptor 4 (CCR4). The CCR4 system is considered to be responsible for the pathology of allergic diseases such as atopic dermatitis. To find and develop potential medicines against allergic diseases, we screened an in-house library to search for compounds having a profile as a CCR4 antagonist. From among the screening hits, we focused on 3-{2-[(2R)-2-phenyl-4-(4-pyridin-4-ylbenzyl)morpholin-2-yl]ethyl}quinazoline-2,4(1H,3H)-dione (named RS-1154), which had been newly synthesized in our laboratory. This compound inhibited the binding of [(125)I]CCL17 to human CCR4-expressing CHO cells with an IC(50) value of 27.7 nM and moreover inhibited CCL17-induced migration of DO11.10 mice-derived T helper 2 cells with an IC(50) value of 1.5 nM in vitro. We then examined the effect of RS-1154 in an ovalbumin-induced ear swelling assay. The ear thickness was decreased by intravenous administration of anti-CCL17 or anti-CCL22 antibodies, suggesting that the CCR4 system is involved in the ear swelling. Though partially, the oral administration of RS-1154 also significantly ameliorated the ear swelling at the doses of 30 and 100 mg/kg. Furthermore, the serum level of interleukin-4 decreased after the administration of RS-1154. In this study, we succeeded in obtaining a newly-synthesized compound, RS-1154, which has a potential to inhibit the chemotaxis of T helper 2 cells in vitro and to ameliorate ovalbumin-induced ear swelling in vivo. These results raise the possibility that RS-1154 or one of derivatives might become a therapeutic agent for atopic dermatitis patients.

Filarial infection in humans is initiated when a mosquito deposits third-stage parasite larvae (L3) in the skin. Langerhans cells (LCs) and dermal dendritic cells (DDCs) are the first cells that the parasite encounters, and L3s must evade these highly effective antigen-presenting cells to establish infection. To assess LC and DDC responses to L3 in human skin, we employed three models of increasing physiologic relevance: in vitro-generated LCs, epidermal blister explants and full-thickness human skin sections. In vitro-generated LCs expressed TLR1-10 and robustly produced IL-6 and TNF-α in response to PolyI:C, but pre-exposure to L3s did not alter inflammatory cytokine production or TLR expression. L3s did not modulate expression of LC markers CDH1, CD207, or CD1a, or the regulatory products TSLP or IDO in epidermal explants or in vitro-generated LC. LC, CD14+ DDC, CD1c+ DC and CD141+ DC from human skin sections were analysed by flow cytometry. While PolyI:C potently induced CCL22 production in LC, CD1c+ DC, and CD141+ DC, and IL-10 production in LC, L3s did not modulate the numbers of or cytokine production by any skin DC subset. L3s broadly failed to activate or modulate LCs or DDCs, suggesting filarial larvae expertly evade APC detection in human skin.

The effects of the amino acid copolymers used in the therapy of experimental autoimmune encephalomyelitis, poly(Y,E,A,K)(n) (Copaxone(®)) and poly(Y,F,A,K)(n), on murine myeloid cells have been investigated. After administration of these copolymers to mice, increases in several splenic myeloid cell populations were observed, including CD11b(+) CD11c(+) dendritic cells. The latter were the major splenic cell type that secreted CCL22 (macrophage-derived chemokine) on stimulation with amino acid copolymers. CCL22 secretion was also stimulated from bone marrow-derived dendritic cells (BMDC) generated with GM-CSF in much larger amounts than from bone marrow-derived macrophages generated with M-CSF. Moreover, CCL22 secretion could also be obtained using BMDC generated from two different types of MHC II(-/-) mice, indicating that an innate immune receptor is involved. Finally, incubation of these BMDC or splenic dendritic cells with naive CD4(+) CD25(-) T cells resulted in formation of CD4(+) CD25(HI) Foxp3 T cells (~25% of which were Foxp3(+)). The number of these regulatory cells was doubled by pretreatment of BMDC with amino acid copolymers.

OBJECTIVE

Chemokines play essential role not only in controlling leukocyte function and trafficking but also in the angiogenesis and modulation of inflammatory responses.

METHODS

A novel array-based enzyme-linked immunosorbent assay was used to quantitate peritoneal fluid chemokines of 25 infertile women with endometriosis and 18 controls. For our preliminary studies we chose mini-array containing nine different chemokines: MDC/CCL22, TARC/CCL17, MCP-1/CCL2, RANTES/CCL5, MIP-1alpha/CCL3, -1beta/CCL4, -1delta/CCL15, -3alpha/CCL20, and -3beta/CCL19.

RESULTS

We found significantly higher MIP-3beta/CCL19 (P = 0.0036) concentrations in peritoneal fluid of women with endometriosis as compared to patients with primary infertility without any signs of disease.

CONCLUSIONS

Our preliminary results suggest that MIP-3beta/ /CCL19 might play a role in the pathogenesis of endometriosis but its precise role remains to be established. Novel types of screening methods based on high-throughput technologies offer great opportunities to study immunobiology of endometriosis. It will hopefully provide new possibilities for discovery of new markers and potential drug targets.

Myeloid and plasmacytoid dendritic cells (MDC, PDC) play a key role in the initiation of immune responses. We found a reduction of both DC subsets in 42 patients with chronic lymphocytic leukaemia (CLL) at diagnosis (P<0.0001 and 0.0001 vs. controls, respectively), likely related to the high secretion of CCL22 and CXCL12 (P=0.04 and 0.008 vs. controls, respectively) by leukaemic cells. However, CD14+ monocytes from CLL patients could give rise to functional IL-12p70-secreting monocyte-derived DCs, capable of inducing a type 1 polarization immunostimulatory profile. These monocyte-derived DCs from CLL patients efficiently migrate in response to CCL19/MIP-3beta chemokine, suggesting that functional autologous DCs can be generated for immunotherapeutic purposes to circumvent DC defects in CLL.

A series of CC chemokine receptor-4 (CCR4) antagonists were examined in a previous report in an attempt to improve metabolic stability in human liver microsomes. In this study, the cycloheptylamine moiety of N-cycloheptyl-6,7-dimethoxy-2-(4-pyrrolidin-1-ylpiperidin-1-yl)quinazolin-4-amine 1 was replaced with the p-chloroaniline moiety, and the resulting compound, N-(4-chlorophenyl)-6,7-dimethoxy-2-(4-pyrrolidin-1-ylpiperidin-1-yl)quinazolin-4-amine (8c), retained its potency ([(35)S]GTPgammaS-binding inhibition and CCL22-induced chemotaxis in humans/mice). Based on the structure-activity relationships (SAR), a homology model was constructed for CCR4 to explain the binding mode of 8c. Overall, there was good agreement between the docking pose of the CCR4 homology model and the human [(35)S]GTPgammaS assay results. Administration of 8c in a murine model of acute dermatitis showed anti-inflammatory activity (oxazolone-induced contact hypersensitivity test).

CCR4 is highly expressed on Th2 cells. CCR4 ligands include CCL22 and CCL17. Chemokine-like factor 1 can also mediate chemotaxis via CCR4. We designed and synthetized novel CCR4 antagonists, which were piperazinyl pyridine derivatives, for disrupting the interaction between three ligands and CCR4. We also determined whether these novel CCR4 antagonists could alleviate allergic asthma in a mouse. For identifying the potent compounds in vitro, we used chemotaxis inhibition and competition binding assays induced by CCL22, CCL17 and one of CKLF1's C-terminal peptides, C27. We found compound 8a which showed excellent potency in blocking the interaction of CCR4 and its three ligands. For studying the specificity of compounds, we chose chemotaxis inhibition assays with different receptors and ligands. We found compound 8a had excellent receptor specificity and exerted few influence on the interaction of other receptors and their ligands. In the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, compound 8a had no obvious cytotoxicity till the higher concentration (16 μM). For determining the potency of compounds in blocking the interaction of CCR4 in vivo, we used the ovalbumin induced allergic asthma model in mice. Our study demonstrated that CCR4 blockaded by compound 8a effectively attenuated airway hyperresponsiveness, airway eosinophilia and Th2 cytokines.

BACKGROUND

Thymus- and activation-regulated chemokine (TARC) and macrophage-derived chemokine (MDC) are accepted to be important molecules in the development and maintenance of allergic diseases. Although several types of histamine H(1) receptor antagonist (antihistamine) have been developed and used for the treatment of allergic diseases, the influence of antihistamines on TARC and MDC production is not well understood.

OBJECTIVE

The present study was undertaken to examine the influence of antihistamines on TARC and MDC production from CD14+ cells after antigenic stimulation in vitro.

METHODS

CD14+ cells prepared from patients with pollinosis to Japanese cedar pollen were stimulated with specific allergen extracted from Japanese cedar pollen (Cry j 1) in the presence of azelastine (AZE), ketotifen (KET), fexofenadine (FEX) and oxatomide (OXA) for 6 days. TARC and MDC levels in culture supernatants were examined by ELISA. We also examined the influence of FEX on TARC and MDC mRNA expression, phosphorylation of mitogen-activated protein kinases (MAPKs) and transcription factor activation in CD14+ cells after Cry j 1 stimulation.

RESULTS

FEX at 250 ng/ml, which is almost equal to therapeutic blood levels, caused a significant inhibition of TARC and MDC production.However, AZE, OXA and KET required higher concentrations than their therapeutic blood levels to suppress production of these factors. FEX at 250 ng/ml also suppressed NF-κB activation, phosphorylation of p38 MAPK and extracellular signal-regulated kinases 1 and 2 and expression of mRNA for TARC and MDC.

CONCLUSIONS

These results suggest that antihistamines, especially FEX, suppress CC chemokine production from CD14+ cells through interference with antigen-mediated signaling and result in favorable modification of allergic disease states or conditions.

Regulatory T cells (Tregs) have been shown to regulate the immune response and to control the defense against infection in periapical lesions, but the underlying mechanisms by which Tregs are recruited to these lesions remain unknown. Here we demonstrate that expression of the gene encoding CCL22 (also known as macrophage-derived chemokine), the major chemoattractant that recruits Tregs, is upregulated in periapical tissue during the progression of experimental periapical lesions; this upregulation positively correlated with the number of Tregs that accumulated in the lesions. In terms of mechanism, we determined that lipopolysaccharide (LPS) up-regulates Ccl22 expression in macrophages by suppressing miR-34a. These findings suggest that the LPS-miR-34a-CCL22 axis may contribute to the recruitment of Tregs in periapical lesions, providing a potential therapeutic target for controlling this disease.

This systematic review aimed to: (a) generate a descriptive synthesis of preclinical studies assessing the therapeutic potential of regulatory T lymphocytes (Tregs) to arrest periodontitis, (b) evaluate the methodological heterogeneity of the reviewed animal studies and (c) assess the risk of bias (RoB) of the included studies. The electronic search for animal studies included the MEDLINE, EMBASE, Web of Science and LILACS databases. In addition, a manual search assessed the high-ranked scientific journals in "periodontics/immunology" and the references listed in the included studies. There were no language, year or publication status restrictions. Two independent reviewers selected and extracted the data, and Cohen's Kappa coefficient was calculated to determine the inter-examiner agreement. The Systematic Review Center for Laboratory Animal Experimentation's (SYRCLE) tool was used to assess the RoB. A total of 21 of the 425 studies obtained from the database search were included. Treg function was mainly described in Porphyromonas gingivalis-induced periodontitis (57.1%) in mice (76.2%), where Treg suppression was strongly related to disease progression and Treg induction was strongly related to immuno-inflammatory response reduction. Of those 21 studies, eight included eight animal experiments using three distinct therapeutic approaches, including: P. gingivalis-driven immunization (n = 3), retinoic acid inoculation (n = 2) and anti-inflammatory molecules in polymeric carriers (n = 3), which could modulate the Treg activity through cytokine production (interleukin-10 and transforming growth factor-β1), CC-chemokine- and CC-chemokine receptor-mediated chemoattraction (CCL22 and CCR4) or Th17-associated receptor activator of nuclear factor κB ligand (RANKL) downregulation. However, the studies with animal experiments did not specify the randomization sequences and housing conditions that were used, and therefore, 42.11% of the entries were rated as unclear RoB. Distinct therapeutic strategies involving Tregs could potentially suppress the immuno-inflammatory response and restore alveolar bone homeostasis during periodontitis. Nevertheless, important methodological variability, poor reporting of treatment effect estimates and unclear RoB suggest using caution when assessing the results of these studies.

CCR4 is a major chemokine receptor expressed by Treg cells and Th17 cells. While Treg cells are known to suppress antitumor immunity, Th17 cells have recently been shown to enhance the induction of antitumor cytotoxic T lymphocytes. Here, CCR4-deficient mice displayed enhanced tumor growth upon intradermal inoculation of B16-F10 melanoma cells. In CCR4-deficient mice, while IFN-γ+CD8+ effector T cells were decreased in tumor sites, IFN-γ+CD8+ T cells and Th17 cells were decreased in regional lymph nodes. In wild-type mice, CD4+IL-17A+ cells, which were identified as CCR4+CD44+ memory Th17, were found to be clustered around dendritic cells expressing MDC/CCL22, a ligand for CCR4, in regional lymph nodes. Compound 22, a CCR4 antagonist, also enhanced tumor growth and decreased Th17 cells in regional lymph nodes in tumor-bearing mice treated with Dacarbazine. In contrast, CCR6 deficiency did not affect the tumor growth and the numbers of Th17 cells in regional lymph nodes. These findings indicate that CCR4 is critically involved in regional lymph node DC-Th17 cell interactions that are necessary for Th17 cell-mediated induction of antitumor CD8+ effector T cells in mice bearing B16 melanoma.

Wound healing is a well-coordinated process that involves inflammatory mediators and cellular responses; however, if any disturbances are present during this process, tissue repair is impaired. Chronic wounds are one of the serious long-term complications associated with diabetes mellitus (DM). The chemokine receptor CCR4 and its respective ligands, CCL17 and CCL22, are involved in regulatory T cell (Treg) recruitment and activation in inflamed skin; however, the role of Treg in wounds is still not clear. Our aim was to investigate the role of CCR4 and Treg in cutaneous wound healing in diabetic mice. Alloxan-induced diabetic wild- type mice (diabetic) developed wounds that were difficult to heal, differently from CCR4-/- diabetic mice (CCR4-/- diabetic), and also from anti-CCL17/22 or anti-CD25 injected diabetic mice that presented with accelerated wound healing and less Treg in the wound bed. Consequently, CCR4-/- diabetic mice also presented with alteration on T cells population in the wound and draining lymph nodes; on the 14th day, these mice also displayed an increase of collagen fiber deposition. Still, cytokine levels were decreased in the wounds of CCR4-/- diabetic mice on the 2nd day. Our data suggest that the receptor CCR4 and Treg negatively affect wound healing in diabetic mice.

We investigated the effects of a topically applied extract of the heartwood of Broussonetia kazinoki Sieb (B. kazinoki) on atopic dermatitis (AD)-like skin lesions induced by an extract of the house-dust mite Dermatophagoides farina in NC/Nga mice. We found that topically applied B. kazinoki extract suppressed the histological manifestations of AD-like skin lesions, and decreased the levels of plasma immunoglobulin E (IgE) and interleukin-4 (IL-4) in the mice. Moreover, B. kazinoki inhibited the induction of thymus-and-activation-regulated chemokine (TARC/CCL17), macrophage-derived chemokine (MDC/CCL22), and regulated-on-activation-normal T cell-expressed-and-secreted chemokine (RANTES/CCL5) in HaCaT cells activated by tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). In conclusion, our results suggest that B. kazinoki extract has therapeutic advantages in the treatment of AD.

BACKGROUND

Pattern recognition receptors are attractive targets for vaccine adjuvants, and polymorphisms of the innate receptor NOD1 have been associated with allergic asthma.

OBJECTIVE

To elucidate whether NOD1 agonist may favor allergic asthma in humans through activation of dendritic cells, and to evaluate the mechanisms involved using an in vivo model.

METHODS

NOD1-primed dendritic cells from allergic and nonallergic donors were characterized in vitro on their phenotype, cytokine secretion, and Th2 polarizing ability. The in vivo relevance was examined in experimental allergic asthma, and the mechanisms were assessed using transfer of NOD1-conditioned dendritic cells from wild-type or CCL17-deficient mice.

RESULTS

NOD1 priming of human dendritic cells promoted a Th2 polarization profile that involved the production of CCL17 and CCL22 in nonallergic subjects but only CCL17 in allergic patients, without requiring allergen costimulation. Moreover, NOD1-primed dendritic cells from allergic donors exhibited enhanced maturation that led to abnormal CCL22 and IL-10 secretion compared with nonallergic donors. In mice, systemic NOD1 ligation exacerbated allergen-induced experimental asthma by amplifying CCL17-mediated Th2 responses in the lung. NOD1-mediated sensitization of purified murine dendritic cells enhanced production of CCL17 and CCL22, but not of thymic stromal lymphopoietin and IL-33, in vitro. Consistently, adoptive transfer of NOD1-conditioned dendritic cells exacerbated the Th2 pulmonary response in a CCL17-dependent manner in vivo.

CONCLUSIONS

Data from this study unveil a deleterious role of NOD1 in allergic asthma through direct induction of CCL17 by dendritic cells, arguing for a need to address vaccine formulation safety issues related to allergy.

Development, course of disease and prognosis of hepatocellular carcinomas (HCC) are strongly influenced by the immune system. Immunosuppressive regulatory T cells (Treg) have been shown to negatively impact disease progression and survival. To further understand the mechanisms of Treg attraction to HCC lesions, this study provides an analysis of Treg attracting chemokines in human HCC tissues. We analysed the expression of the Treg attracting chemokines CCL1 and CCL22 as well as the infiltration of FoxP3+ Treg and CD8+ T cells in paraffin-embedded tissue sections of 62 HCC patients. Expression of both chemokines was detected in 47 of 62 tissue slides. Chemokine expression was generally higher in tumour stroma and peritumoural liver tissue than in the tumour tissue itself. CD8+ T cells and FoxP3+ Treg were found at high levels in many tumour tissues. Intratumoural infiltration of Treg positively correlated with CCL22 levels in peritumoural liver tissue. In contrast, no correlation of Treg numbers and expression of CCL1 was detected. In summary, we describe here that the chemokines CCL1 and CCL22 are expressed in HCC tissues and, to a higher extent, in the stroma and peritumoural liver tissue. CCL22 may contribute to Treg recruitment and immunosuppression, whereas the role of CCL1 remains to be defined. It will be interesting to investigate the potential of these chemokines as drug targets for cancer therapy.

Inflammation often induces regeneration to repair the tissue damage. However, chronic inflammation can transform temporary hyperplasia into a fertile ground for tumorigenesis. Here, we demonstrate that the microRNA miR-34a acts as a central safeguard to protect the inflammatory stem cell niche and reparative regeneration. Although playing little role in regular homeostasis, miR-34a deficiency leads to colon tumorigenesis after Citrobacter rodentium infection. miR-34a targets both immune and epithelial cells to restrain inflammation-induced stem cell proliferation. miR-34a targets Interleukin six receptor (IL-6R) and Interleukin 23 receptor (IL-23R) to suppress T helper 17 (Th17) cell differentiation and expansion, targets chemokine CCL22 to hinder Th17 cell recruitment to the colon epithelium, and targets an orphan receptor Interleukin 17 receptor D (IL-17RD) to inhibit IL-17-induced stem cell proliferation. Our study highlights the importance of microRNAs in protecting the stem cell niche during inflammation despite their lack of function in regular tissue homeostasis.

Allergic asthma is a complex inflammatory disease that leads to significant healthcare costs and reduction in quality of life. Although many cell types are implicated in the pathogenesis of asthma, CD4+ T-helper cell type 2 (Th2) cells are centrally involved. We previously reported that the asthma phenotype is virtually absent in ovalbumin-sensitized and -challenged mice that lack global expression of β-arrestin (β-arr)-2 and that CD4+ T cells from these mice displayed significantly reduced CCL22-mediated chemotaxis. Because CCL22-mediated activation of CCR4 plays a role in Th2 cell regulation in asthmatic inflammation, we hypothesized that CCR4-mediated migration of CD4+ Th2 cells to the lung in asthma may use β-arr-dependent signaling. To test this hypothesis, we assessed the effect of various signaling inhibitors on CCL22-induced chemotaxis using in vitro-polarized primary CD4+ Th2 cells from β-arr2-knockout and wild-type mice. Our results show, for the first time, that CCL22-induced, CCR4-mediated Th2 cell chemotaxis is dependent, in part, on a β-arr2-dependent signaling pathway. In addition, we show that this chemotactic signaling mechanism involves activation of P-p38 and Rho-associated protein kinase. These findings point to a proinflammatory role for β-arr2-dependent signaling and support β-arr2 as a novel therapeutic target in asthma.