Mesenchymal stromal cells (MSCs) tend to infiltrate into tumors and form a major component of the tumor microenvironment. Our previous work demonstrated that tumor necrosis factor α (TNFα)-activated MSCs significantly promoted tumor growth. However, the role of TNFα-treated MSCs in tumor metastasis remains elusive. Employing a lung metastasis model of murine breast cancer, we found that TNFα-activated MSCs strikingly enhanced tumor metastasis compared with normal MSCs. We analyzed the chemokine profiles and found that the expression of CCL5, CCR2 and CXCR2 ligands were enhanced in TNFα-activated MSCs. Using genetic or pharmacological strategies to inhibit CCL5 or CCR2, we demonstrated that CCL5 and CCR2 ligands were indispensable in supporting TNFα-activated MSCs to promote tumor metastasis. Analysis of immune cells revealed that CXCR2 ligands (CXCL1, CXCL 2 and CXCL5) expressed by TNFα-activated MSCs efficiently recruited CXCR2+ neutrophils into tumor. These neutrophils were responsible for the pro-metastatic effect of MSCs since inhibition of this chemotaxis abolished increased neutrophil recruitment and tumor metastasis. The interaction between neutrophils and tumor cells resulted in markedly elevated metastasis-related genes by tumor cells, including CXCR4, CXCR7, MMP12, MMP13, IL-6 and TGFβ. Importantly, in IL8high human breast cancer samples, we also observed similar alterations of gene expression. Collectively, our findings demonstrate that TNFα-activated MSCs promote tumor metastasis via CXCR2+ neutrophil recruitment.

Sensitization to fungi, such as the mold Aspergillus fumigatus, is increasingly becoming linked with asthma severity. We have previously shown that lung responses generated via the β-glucan receptor Dectin-1 are required for lung defense during acute, invasive A. fumigatus infection. Unexpectedly, in an allergic model of chronic lung exposure to live A. fumigatus conidia, β-glucan recognition via Dectin-1 led to the induction of multiple proallergic (Muc5ac, Clca3, CCL17, CCL22, and IL-33) and proinflammatory (IL-1β and CXCL1) mediators that compromised lung function. Attenuated proallergic and proinflammatory responses in the absence of Dectin-1 were not associated with changes in Ido (IDO), Il12p35/Ebi3 (IL-35), IL-10, or TGF-β levels. Assessment of Th responses demonstrated that purified lung CD4(+) T cells produced IL-4, IL-13, IFN-γ, and IL-17A, but not IL-22, in a Dectin-1-dependent manner. In contrast, we observed robust, Dectin-1-dependent IL-22 production by unfractionated lung digest cells. Intriguingly, the absence of IL-22 alone mimicked the attenuated proallergic and proinflammatory responses observed in the absence of Dectin-1, suggesting that Dectin-1-mediated IL-22 production potentiated responses that led to decrements in lung function. To this end, neutralization of IL-22 improved lung function in normal mice. Collectively, these results indicate that the β-glucan receptor Dectin-1 contributes to lung inflammation and immunopathology associated with persistent fungal exposure via the production of IL-22.

BACKGROUND

The early inflammatory response during reperfusion of cardiac allografts is initiated by the infiltration of polymorphonuclear leukocytes (PMNs) into the graft. The impact of early PMN infiltration on allograft rejection compared with long-term graft survival remains poorly understood.

RESULTS

We tested the role of CXCR2, the receptor for 2 PMN attractant chemokines, KC/CXCL1 and MIP-2/CXCL2, on intragraft inflammation and vascularized cardiac allograft rejection in a murine model. Compared with allografts retrieved from control recipients, both PMN infiltration and intragraft proinflammatory cytokine expression were significantly attenuated in allografts from CXCR2-antisera-treated wild-type or from CXCR2(-/-) recipients. Adoptive transfer of alloantigen-primed T cells rapidly infiltrated and rejected allografts in control recipients, but T-cell infiltration was significantly decreased in recipients depleted of PMNs at transplantation. The influence of early PMN-mediated inflammation on the therapeutic efficacy of costimulatory blockade to prevent allograft rejection was tested. Short-term treatment of recipients with anti-CD154 mAb or CTLA-4 Ig induced modest prolongation of cardiac allograft survival. However, CD154 mAb or CTLA-4 Ig treatment, combined with either peritransplantation PMN depletion or antibodies specific for KC/CXCL1 plus MIP-2/CXCL2, prolonged cardiac allograft survival beyond 100 days.

CONCLUSIONS

Results suggest that strategies attenuating PMN-mediated tissue damage during reperfusion significantly improve the efficacy of short-term costimulatory blockade to prevent T-cell-mediated rejection of cardiac allografts.

CXCL5, a member of the CXC family of chemokines, contributes to neutrophil recruitment during lung inflammation, but its regulation is poorly understood. Because the T cell-derived cytokine IL-17A enhances host defense by triggering production of chemokines, particularly in combination with TNF-α, we hypothesized that IL-17A would enhance TNF-α-induced expression of CXCL5. Intratracheal coadministration of IL-17A and TNF-α in mice induced production of CXCL1, CXCL2, and CXCL5, which was associated with increased neutrophil influx in the lung at 8 and 24 h. The synergistic effects of TNF-α and IL17A were greatly attenuated in Cxcl5(-/-) mice at 24 h, but not 8 h, after exposure, a time when CXCL5 expression was at its peak in wild-type mice. Bone marrow chimeras produced using Cxcl5(-/-) donors and recipients demonstrated that lung-resident cells were the source of CXCL5. Using differentiated alveolar epithelial type II (ATII) cells derived from human fetal lung, we found that IL-17A enhanced TNF-α-induced CXCL5 transcription and stabilized TNF-α-induced CXCL5 transcripts. Whereas expression of CXCL5 required activation of NF-κB, IL-17A did not increase TNF-α-induced NF-κB activation. Apical costimulation of IL-17A and TNF-α provoked apical secretion of CXCL5 by human ATII cells in a transwell system, whereas basolateral costimulation led to both apical and basolateral secretion of CXCL5. The observation that human ATII cells secrete CXCL5 in a polarized fashion may represent a mechanism to recruit neutrophils in host defense in a fashion that discriminates the site of initial injury.

IL-17 (IL-17A) has emerged as a key mediator of protection against extracellular microbes, but this cytokine also drives pathology in various autoimmune diseases. Overwhelming data in both humans and mice reveal a clear and surprisingly specific role for IL-17 in protection against the fungus Candida albicans, a commensal microbe of the human oral cavity, gastrointestinal tract, and reproductive mucosa. The IL-17 pathway regulates antifungal immunity through upregulation of proinflammatory cytokines, including IL-6, neutrophil-recruiting chemokines (e.g., CXCL1 and CXCL5), and antimicrobial peptides (e.g., defensins), which act in concert to limit fungal overgrowth. This review focuses on diseases caused by C. albicans, the role of IL-17-mediated immunity in candidiasis, and the implications for clinical therapies for both autoimmune conditions and fungal infections.

Interleukin 17 (IL-17) is important in infection and autoimmunity; how it signals remains poorly understood. In this study, we identified the ubiquitin-specific protease USP25 as a negative regulator of IL-17-mediated signaling and inflammation. Overexpression of USP25 inhibited IL-17-triggered signaling, whereas USP25 deficiency resulted in more phosphorylation of the inhibitor IκBα and kinase Jnk and higher expression of chemokines and cytokines, as well as a prolonged half-life for chemokine CXCL1-encoding mRNA after treatment with IL-17. Consistent with that, Usp25(-/-) mice showed greater sensitivity to IL-17-dependent inflammation and autoimmunity in vivo. Mechanistically, stimulation with IL-17 induced the association of USP25 with the adaptors TRAF5 and TRAF6, and USP25 induced removal of Lys63-linked ubiquitination in TRAF5 and TRAF6 mediated by the adaptor Act1. Thus, our results demonstrate that USP25 is a deubiquitinating enzyme (DUB) that negatively regulates IL-17-triggered signaling.

OBJECTIVE

Chlorogenic acid, which belongs to the polyphenols, is an anti-oxidant and anti-obesity agent. In this study, we investigated the role of chlorogenic acid in inflammation.

METHODS

Anti-inflammatory effects of chlorogenic acid were examined in lipopolysaccharide (LPS)-stimulated murine RAW 264.7 macrophages and BV2 microglial cells. We observed the level of various inflammation markers such as nitric oxide (NO), inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and chemokine (C-X-C motif) ligand 1 (CXCL1) under LPS treatment with or without chlorogenic acid. To clarify the specific effect of chlorogenic acid, we evaluated the adhesion activity of macrophages and ninjurin1 (Ninj1) expression level in macrophages. Finally, we confirmed the activation of the nuclear factor-κB (NF-κB) signaling pathway, which is one of the most important transcription factors in the inflammatory process.

RESULTS

Chlorogenic acid significantly inhibited not only NO production but also the expression of COX-2 and iNOS, without any cytotoxicity. Chlorogenic acid also attenuated pro-inflammatory cytokines (including IL-1β and TNF-α) and other inflammation-related markers such as IL-6 in a dose-dependent manner. Additionally, endotoxin-induced adhesion of macrophages and the expression level of ninjurin1 (Ninj1) were decreased by chlorogenic acid. Finally, chlorogenic acid inhibited the nuclear translocation of NF-κB.

CONCLUSIONS

Chlorogenic acid may be beneficial for the prevention and treatment of anti-inflammatory diseases.

Macrophage inflammatory protein-3alpha (MIP-3alpha)/CCL20 and MIP-3beta/CCL19 are members of the CC chemokine subfamily which exert their effects through specific receptors, CCR6 and CCR7, respectively. Previously, we have reported that human neutrophils have the capacity to produce a number of chemokines, including IL-8/CXCL8, GROalpha/<em>CXCL1</em>, IP-10/<em>CXCL1</em>0, and MIG/CXCL9. Herein, we show that neutrophils also have the ability to express and release MIP-3alpha/CCL20 and MIP-3beta/CCL19 when cultured with either LPS or TNF-alpha. We also report that MIP-3alpha/CCL20 and MIP-3beta/CCL19 production by LPS-stimulated neutrophils is negatively modulated by IL-10. Remarkably, we found that supernatants harvested from stimulated neutrophils not only induced chemotaxis of both immature and mature dendritic cells (DC), but also triggered rapid integrin-dependent adhesion of CCR6- and CCR7-expressing lymphocytes to purified VCAM-1 and ICAM-1, respectively. Importantly, both chemotaxis and rapid integrin-dependent adhesion were dramatically suppressed by anti-MIP-3alpha/CCL20 and anti-MIP-3beta/CCL19 neutralizing antibodies, indicating that MIP-3alpha/CCL20 and MIP-3beta/CCL19 present in the supernatants were both biologically active. As these chemokines are primarily chemotactic for DC and specific lymphocyte subsets, the ability of neutrophils to produce MIP-3alpha/CCL20 and MIP-3beta/CCL19 might be significant in orchestrating the recruitment of these cell types to the inflamed sites and therefore in contributing to the regulation of the immune response.

We report that IL-17 significantly increases the secretion of CXCL1 and CXCL5 from mammary carcinoma cells, which is downregulated by TGF-β through the type II TGF-β receptor (TβRII). Carcinoma cells with conditional knockout of TβRII (Tgfbr2(KO)) have enhanced sensitivity to IL-17a in the stimulation of chemokine secretion. During polyoma middle T (PyMT) induced tumor progression, levels of Th17 inducing cytokines TGF-β, IL-6, IL-23 were increased in PyMT/Tgfbr2(KO) tumors, which was associated with an increased number of Th17 cells. IL-17 increased the suppressive function of MDSCs on T cells through the upregulation of Arg, IDO, and COX2. Treatment of PyMT/Tgfbr2(KO) mice with anti-IL-17 Ab decreased carcinoma growth and metastatic burden. Analysis of human breast cancer transcriptome databases showed a strong association between IL-17 gene expression and poor outcome in lymph node positive, estrogen receptor negative or luminal B subtypes suggesting potential therapeutic approaches.

IL-23/IL-17-induced neutrophil recruitment plays a pivotal role in rheumatoid arthritis (RA). However, the mechanism of the neutrophil recruitment is obscure. Here we report that prostaglandin enhances the IL-23/IL-17-induced neutrophil migration in a murine model of RA by inhibiting IL-12 and IFN gamma production. Methylated BSA (mBSA) and IL-23-induced neutrophil migration was inhibited by anti-IL-23 and anti-IL-17 antibodies, COX inhibitors, IL-12, or IFNgamma but was enhanced by prostaglandin E(2) (PGE(2)). IL-23-induced IL-17 production was increased by PGE(2) and suppressed by COX-inhibition or IL-12. Furthermore, COX inhibition failed to reduce IL-23-induced neutrophil migration in IL-12- or IFNgamma-deficient mice. IL-17-induced neutrophil migration was not affected by COX inhibitors, IL-12, or IFNgamma but was inhibited by MK886 (a leukotriene synthesis inhibitor), anti-TNFalpha, anti-CXCL1, and anti-CXCL5 antibodies and by repertaxin (a CXCR1/2 antagonist). These treatments all inhibited mBSA- or IL-23-induced neutrophil migration. IL-17 induced neutrophil chemotaxis through a CXC chemokines-dependent pathway. Our results suggest that prostaglandin plays an important role in IL-23-induced neutrophil migration in arthritis by enhancing IL-17 synthesis and by inhibiting IL-12 and IFNgamma production. We thus provide a mechanism for the pathogenic role of the IL-23/IL-17 axis in RA and also suggest an additional mechanism of action for nonsteroidal anti-inflammatory drugs.

Members of the IL-17 cytokine family play an important role in protection against pathogens through the induction of different effector mechanisms. We determined that IL-17A, IL-17E and IL-17F are produced during the acute phase of T. cruzi infection. Using IL-17RA knockout (KO) mice, we demonstrate that IL-17RA, the common receptor subunit for many IL-17 family members, is required for host resistance during T. cruzi infection. Furthermore, infected IL-17RA KO mice that lack of response to several IL-17 cytokines showed amplified inflammatory responses with exuberant IFN-γ and TNF production that promoted hepatic damage and mortality. Absence of IL-17RA during T. cruzi infection resulted in reduced CXCL1 and CXCL2 expression in spleen and liver and limited neutrophil recruitment. T. cruzi-stimulated neutrophils secreted IL-10 and showed an IL-10-dependent suppressive phenotype in vitro inhibiting T-cell proliferation and IFN-γ production. Specific depletion of Ly-6G+ neutrophils in vivo during T. cruzi infection raised parasitemia and serum IFN-γ concentration and resulted in increased liver pathology in WT mice and overwhelming wasting disease in IL-17RA KO mice. Adoptively transferred neutrophils were unable to migrate to tissues and to restore resistant phenotype in infected IL-17RA KO mice but migrated to spleen and liver of infected WT mice and downregulated IFN-γ production and increased survival in an IL-10 dependent manner. Our results underscore the role of IL-17RA in the modulation of IFN-γ-mediated inflammatory responses during infections and uncover a previously unrecognized regulatory mechanism that involves the IL-17RA-mediated recruitment of suppressive IL-10-producing neutrophils.

Cancer is a life-threatening disease world-wide and colorectal cancer is the second common cause of cancer mortality. The interaction between tumor cells and stromal cells plays a crucial role in tumor initiation and progression and is partially mediated by chemokines. Chemokines predominantly participate in the chemoattraction of leukocytes to inflammatory sites. Nowadays, it is clear that CXC chemokines and their receptors (CXCR) may also modulate tumor behavior by several important mechanisms: regulation of angiogenesis, activation of a tumor-specific immune response by attracting leukocytes, stimulation of tumor cell proliferation and metastasis. Here, we review the expression and complex roles of CXC chemokines (<em>CXCL1</em> to <em>CXCL1</em>6) and their receptors (CXCR1 to CXCR6) in colorectal cancer. Overall, increased expression levels of CXC chemokines correlate with poor prognosis.

OBJECTIVE

To evaluate the efficacy of epigallocatechin-3-gallate (EGCG), a potent antiinflammatory molecule, in regulating interleukin-1beta (IL-1beta)-induced production of the chemokines RANTES (CCL5), monocyte chemoattractant protein 1 (MCP-1/CCL2), epithelial neutrophil-activating peptide 78 (ENA-78/CXCL5), growth-regulated oncogene alpha (GROalpha/CXCL1), and matrix metalloproteinase 2 (MMP-2) activity in rheumatoid arthritis (RA) synovial fibroblasts.

METHODS

Fibroblasts obtained from RA synovium were grown, and conditioned medium was obtained. Cell viability was determined by MTT assay. RANTES, MCP-1, ENA-78, and GROalpha produced in culture supernatants were measured by enzyme-linked immunosorbent assay. MMP-2 activity was analyzed by gelatin zymography. Western blotting was used to study the phosphorylation of protein kinase C (PKC) isoforms and nuclear translocation of NF-kappaB.

RESULTS

EGCG was nontoxic to RA synovial fibroblasts. Treatment with EGCG at 10 microM or 20 microM significantly inhibited IL-1beta-induced ENA-78, RANTES, and GROalpha, but not MCP-1 production in a concentration-dependent manner. EGCG at 50 microM caused a complete block of IL-1beta-induced production of RANTES, ENA-78, and GROalpha, and reduced production of MCP-1 by 48% (P < 0.05). Zymography showed that EGCG blocked constitutive, IL-1beta-induced, and chemokine-mediated MMP-2 activity. Evaluation of signaling events revealed that EGCG preferentially blocked the phosphorylation of PKCdelta and inhibited the activation and nuclear translocation of NF-kappaB in IL-1beta-treated RA synovial fibroblasts.

CONCLUSIONS

These results suggest that EGCG may be of potential therapeutic value in inhibiting joint destruction in RA.

General interest in the biological functions of IFN type I in Mycobacterium tuberculosis (Mtb) infection increased after the recent identification of a distinct IFN gene expression signature in tuberculosis (TB) patients. Here, we demonstrate that TB-susceptible mice lacking the receptor for IFN I (IFNAR1) were protected from death upon aerogenic infection with Mtb. Using this experimental model to mimic primary progressive pulmonary TB, we dissected the immune processes affected by IFN I. IFNAR1 signaling did not affect T-cell responses, but markedly altered migration of inflammatory monocytes and neutrophils to the lung. This process was orchestrated by IFNAR1 expressed on both immune and tissue-resident radioresistant cells. IFNAR1-driven TB susceptibility was initiated by augmented Mtb replication and in situ death events, along with CXCL5/CXCL1-driven accumulation of neutrophils in alveoli, followed by the discrete compartmentalization of Mtb in lung phagocytes. Early depletion of neutrophils rescued TB-susceptible mice to levels observed in mice lacking IFNAR1. We conclude that IFN I alters early innate events at the site of Mtb invasion leading to fatal immunopathology. These data furnish a mechanistic explanation for the detrimental role of IFN I in pulmonary TB and form a basis for understanding the complex roles of IFN I in chronic inflammation.

Human rhinovirus (RV) infection is responsible for the majority of virus-induced asthma exacerbations. Using a mouse model of human RV infection, we sought to determine the requirement of CXCR2, the receptor for ELR-positive CXC chemokines, for RV-induced airway neutrophilia and hyperresponsiveness. Wild-type and CXCR2(-/-) mice were inoculated intranasally with RV1B or sham HeLa cell supernatant. Following RV1B infection, CXCR2(-/-) mice showed reduced airway and lung neutrophils and cholinergic responsiveness compared with wild-type mice. Similar results were obtained in mice treated with neutralizing Ab to Ly6G, a neutrophil-depleting Ab. Lungs from RV-infected, CXCR2(-/-) mice showed significantly reduced production of TNF-alpha, MIP-2/CXCL2, and KC/CXCL1 and lower expression of MUC5B compared with RV-treated wild-type mice. The requirement of TNF-alpha for RV1B-induced airway responses was tested using TNFR1(-/-) mice. TNFR1(-/-) animals displayed reduced airway responsiveness to RV1B, even when exogenous MIP-2 was added to the airways. We conclude that CXCR2 is required for RV-induced neutrophilic airway inflammation and that neutrophil TNF-alpha release is required for airway hyperresponsiveness.

We previously demonstrated that exposure to febrile-range hyperthermia (FRH) accelerates pathogen clearance and increases survival in murine experimental Klebsiella pneumoniae peritonitis. However, FRH accelerates lethal lung injury in a mouse model of pulmonary oxygen toxicity, suggesting that the lung may be particularly susceptible to injurious effects of FRH. In the present study, we tested the hypothesis that, in contrast with the salutary effect of FRH in Gram-negative peritonitis, FRH would be detrimental in multilobar Gram-negative pneumonia. Using a conscious, temperature-clamped mouse model and intratracheal inoculation with K. pneumoniae Caroli strain, we showed that FRH tended to reduce survival despite reducing the 3 day-postinoculation pulmonary pathogen burden by 400-fold. We showed that antibiotic treatment rescued the euthermic mice, but did not reduce lethality in the FRH mice. Using an intratracheal bacterial endotoxin LPS challenge model, we found that the reduced survival in FRH-treated mice was accompanied by increased pulmonary vascular endothelial injury, enhanced pulmonary accumulation of neutrophils, increased levels of IL-1beta, MIP-2/CXCL213, GM-CSF, and KC/CXCL1 in the bronchoalveolar lavage fluid, and bronchiolar epithelial necrosis. These results suggest that FRH enhances innate host defense against infection, in part, by augmenting polymorphonuclear cell delivery to the site of infection. The ultimate effect of FRH is determined by the balance between accelerated pathogen clearance and collateral tissue injury, which is determined, in part, by the site of infection.

OBJECTIVE

Host-microbial interactions are central in health and disease. Monosodium urate monohydrate (MSU) crystals cause gout by activating the NLRP3 inflammasome, leading to interleukin-1β (IL-1β) production and neutrophil recruitment. This study was undertaken to investigate the relevance of gut microbiota, acetate, and the metabolite-sensing receptor GPR43 in regulating inflammation in a murine model of gout.

METHODS

Gout was induced by the injection of MSU crystals into the knee joints of mice. Macrophages from the various animals were stimulated to determine inflammasome activation and production of reactive oxygen species (ROS).

RESULTS

Injection of MSU crystals caused joint inflammation, as seen by neutrophil influx, hypernociception, and production of IL-1β and CXCL1. These parameters were greatly decreased in germ-free mice, mice treated with antibiotics, and GPR-43-deficient mice. Recolonization or administration of acetate to germ-free mice restored inflammation in response to injection of MSU crystals. In vitro, macrophages produced ROS and assembled the inflammasome when stimulated with MSU. Macrophages from germ-free animals produced little ROS, and there was little inflammasome assembly. Similar results were observed in macrophages from GPR-43-deficient mice. Treatment of germ-free mice with acetate restored in vitro responsiveness of macrophages to MSU crystals.

CONCLUSIONS

In the absence of microbiota, there is decreased production of short-chain fatty acids that are necessary for adequate inflammasome assembly and IL-1β production in a manner that is at least partially dependent on GPR43. These results clearly show that the commensal microbiota shapes the host's ability to respond to an inflammasome-dependent acute inflammatory stimulus outside the gut.

IL-22 is made by a unique set of innate and adaptive immune cells, including the recently identified noncytolytic NK, lymphoid tissue-inducer, Th17, and Th22 cells. The direct effects of IL-22 are restricted to nonhematopoietic cells, its receptor expressed on the surface of only epithelial cells and some fibroblasts in various organs, including parenchymal tissue of the gut, lung, skin, and liver. Despite this cellular restriction on IL-22 activity, we demonstrate that IL-22 induces effects on systemic biochemical, cellular, and physiological parameters. By utilizing adenoviral-mediated delivery of IL-22 and systemic administration of IL-22 protein, we observed that IL-22 modulates factors involved in coagulation, including fibrinogen levels and platelet numbers, and cellular constituents of blood, such as neutrophil and RBC counts. Furthermore, we observed that IL-22 induces thymic atrophy, body weight loss, and renal proximal tubule metabolic activity. These cellular and physiological parameters are indicative of a systemic inflammatory state. We observed that IL-22 induces biochemical changes in the liver including induction of fibrinogen, CXCL1, and serum amyloid A that likely contribute to the reported cellular and physiological effects of IL-22. Based on these findings, we propose that downstream of its expression and impact in local tissue inflammation, circulating IL-22 can further induce changes in systemic physiology that is indicative of an acute-phase response.

Interleukin-17 (IL-17) induces the production of granulocyte colony-stimulating factor (G-CSF) and chemokines such as CXCL1 and CXCL2 and is a cytokine that acts as an inflammation mediator. During infection, IL-17 is needed to eliminate extracellular bacteria and fungi, by inducing antimicrobial peptides such as defensin. This cytokine also plays an important role in chronic inflammation that occurs during the pathogenesis of autoimmune diseases and allergies such as human rheumatoid arthritis (RA) for which a mouse model of collagen-induced arthritis (CIA) is available. In autoimmune diseases such as RA and multiple sclerosis (MS), IL-17 is produced by helper T (Th) cells that are stimulated by IL-1β and IL-6 derived from phagocytes such as macrophages and from tissue cells. IL-17 contributes to various lesions that are produced by Th17 cells, one subset of helper T cells, and by γδ T cells and innate lymphoid cells. It strongly contributes to autoimmune diseases that are accompanied by chronic inflammation. Thus, a functional understanding of Th17 cells is extremely important. In this review, we highlight the roles of cytokines that promote the development and maintenance of pathogenic Th17 cells in autoimmune diseases.

OBJECTIVE

Chemokines orchestrate neutrophil recruitment to inflammatory foci. In the present study, we evaluated the participation of three chemokines, KC/CXCL1, MIP-2/CXCL2 and LIX/CXCL5, which are ligands for chemokine receptor 2 (CXCR2), in mediating neutrophil recruitment in immune inflammation induced by antigen in immunized mice.

METHODS

Neutrophil recruitment was assessed in immunized mice challenged with methylated bovine serum albumin, KC/CXCL1, LIX/CXCL5 or tumour necrosis factor (TNF)-alpha. Cytokine and chemokine levels were determined in peritoneal exudates and in supernatants of macrophages and mast cells by elisa. CXCR2 and intercellular adhesion molecule 1 (ICAM-1) expression was determined using immunohistochemistry and confocal microscopy.

RESULTS

Antigen challenge induced dose- and time-dependent neutrophil recruitment and production of KC/CXCL1, LIX/CXCL5 and TNF-alpha, but not MIP-2/CXCL2, in peritoneal exudates. Neutrophil recruitment was inhibited by treatment with reparixin (CXCR1/2 antagonist), anti-KC/CXCL1, anti-LIX/CXCL5 or anti-TNF-alpha antibodies and in tumour necrosis factor receptor 1-deficient mice. Intraperitoneal injection of KC/CXCL1 and LIX/CXCL5 induced dose- and time-dependent neutrophil recruitment and TNF-alpha production, which were inhibited by reparixin or anti-TNF-alpha treatment. Macrophages and mast cells expressed CXCR2 receptors. Increased macrophage numbers enhanced, while cromolyn sodium (mast cell stabilizer) diminished, LIX/CXCL5-induced neutrophil recruitment. Macrophages and mast cells from immunized mice produced TNF-alpha upon LIX/CXCL5 stimulation. Methylated bovine serum albumin induced expression of ICAM-1 on mesenteric vascular endothelium, which was inhibited by anti-TNF-alpha or anti-LIX/CXCL5.

CONCLUSIONS

Following antigen challenge, CXCR2 ligands are produced and act on macrophages and mast cells triggering the production of TNF-alpha, which synergistically contribute to neutrophil recruitment through induction of the expression of ICAM-1.

The arterial vessel wall response to a variety of injuries consists in structural changes, which can result in luminal narrowing and aggravation of the underlying disease. This arterial remodeling is characterized by neointima formation and medial thickening, inflammatory cell recruitment and endothelial dysfunction. Chemokines and the corresponding receptors have been shown to participate at every step of the remodeling process. The monocyte chemotactic protein (MCP)-1/CC motif receptor 2 (CCR2) axis induces monocyte infiltration of the injured vessel wall and can stimulate proliferation of smooth muscle cells (SMCs) in models of restenosis, cardiac allograft vasculopathy (CAV), pulmonary hypertension, and systemic hypertension. In contrast, stromal cell-derived factor (SDF)-1 alpha and its receptor CXC motif receptor 4 (CXCR4) are centrally involved in the neointimal recruitment of SMC progenitor cells (SPCs), presumably in response to SMC apoptosis, in restenosis and CAV. The RANTES (Regulated upon activation, normally T-cell expressed, and presumably secreted) receptors CC motif receptor 1 (CCR1) and CC motif receptor 5 (CCR5) affect intimal monocyte infiltration and neointimal growth, which could be due to the deposition of platelet-derived RANTES on activated endothelial cells. Fractalkine is expressed on neointimal SMCs and thus mediates the arrest of monocytes. Interestingly, reendothelialization of injured vessels appears to primarily depend on CXC motif ligand 1 (CXCL1). These chemokine effects form a complex network, which operates in all mechanisms of vascular remodeling. The detailed understanding of the function of the chemokine network in the remodeling process may allow specific disease intervention.

BACKGROUND

Although the clinical attributes of severe asthma in children have been well described, the differentiating features of the lower airway inflammatory response are less understood.

OBJECTIVE

We sought to discriminate severe from moderate asthma in children by applying linear discriminant analysis, a supervised method of high-dimensional data reduction, to cytokines and chemokines measured in the bronchoalveolar lavage (BAL) fluid and alveolar macrophage (AM) lysate.

METHODS

Bronchoalveolar lavage fluid was available from 53 children with asthma (severe asthma, n = 31) undergoing bronchoscopy for clinical indications and 30 nonsmoking adults. Twenty-three cytokines and chemokines were measured by using bead-based multiplex assays. Linear discriminant analyses of the BAL fluid and AM analytes were performed to develop predictive models of severe asthma in children.

RESULTS

Although univariate analysis of single analytes did not differentiate severe from moderate asthma in children, linear discriminant analyses allowed for near complete separation of the moderate and severe asthmatic groups. Significant correlations were also noted between several of the AM and BAL analytes measured. In the BAL fluid, IL-13 and IL-6 differentiated subjects with asthma from controls, whereas growth-related oncogene (CXCL1), RANTES (CCL5), IL-12, IFN-gamma, and IL-10 best characterized severe versus moderate asthma in children. In the AM lysate, IL-6 was the strongest discriminator of all the groups.

CONCLUSIONS

Severe asthma in children is characterized by a distinct airway molecular phenotype that does not have a clear T(H)1 or T(H)2 pattern. Improved classification of children with severe asthma may assist with the development of targeted therapeutics for this group of children who are difficult to treat.

Although some signs of inflammation have been reported previously in patients with myalgic encephalomyelitis or chronic fatigue syndrome (ME/CFS), the data are limited and contradictory. High-throughput methods now allow us to interrogate the human immune system for multiple markers of inflammation at a scale that was not previously possible. To determine whether a signature of serum cytokines could be associated with ME/CFS and correlated with disease severity and fatigue duration, cytokines of 192 ME/CFS patients and 392 healthy controls were measured using a 51-multiplex array on a Luminex system. Each cytokine's preprocessed data were regressed on ME/CFS severity plus covariates for age, sex, race, and an assay property of newly discovered importance: nonspecific binding. On average, TGF-β was elevated (P = 0.0052) and resistin was lower (P = 0.0052) in patients compared with controls. Seventeen cytokines had a statistically significant upward linear trend that correlated with ME/CFS severity: CCL11 (Eotaxin-1), <em>CXCL1</em> (GROα), <em>CXCL1</em>0 (IP-10), IFN-γ, IL-4, IL-5, IL-7, IL-12p70, IL-13, IL-17F, leptin, G-CSF, GM-CSF, LIF, NGF, SCF, and TGF-α. Of the 17 cytokines that correlated with severity, 13 are proinflammatory, likely contributing to many of the symptoms experienced by patients and establishing a strong immune system component of the disease. Only CXCL9 (MIG) inversely correlated with fatigue duration.

Emerging evidence suggests that the primary tumor influences the development of supportive metastatic microenvironments, referred to as premetastatic niches, in certain distant organs before arrival of metastatic cells. However, the mechanisms underlying the contributions of the primary tumor to premetastatic niche formation are not fully understood. Here, we demonstrate that colorectal carcinoma cells secrete VEGFA, which stimulates tumor-associated macrophages to produce CXCL1 in the primary tumor. Elevation of CXCL1 in premetastatic liver tissue recruited CXCR2-positive myeloid-derived suppressor cells (MDSC) to form a premetastatic niche that ultimately promoted liver metastases. Importantly, premetastatic liver-infiltrating MDSCs induced tumor cell survival without involvement of innate or adaptive immune responses. Our study provides the first evidence that primary malignant cell-secreted VEGFA stimulates tumor-associated macrophages to produce CXCL1, which recruits CXCR2-positive MDSCs to form a premetastatic niche to promote liver metastases. Our findings not only shed light on how the tumor microenvironment contributes to premetastatic niche formation at distant sites, but they also provide comprehensive insights into how MDSCs are recruited to other organs where they contribute to metastatic spread of disease. Moreover, our work also provides a rationale for development of CXCR2 antagonists to inhibit or prevent metastatic spread of disease. Cancer Res; 77(13); 3655-65. ©2017 AACR.