Inconsequential role for chemerin-like receptor 1 in the manifestation of ozone-induced lung pathophysiology in male mice

We executed this study to determine if chemerin-like receptor 1 (CMKLR1), a Gi/o protein-coupled receptor expressed by leukocytes and non-leukocytes, contributes to the development of phenotypic features of non-atopic asthma, including airway hyperresponsiveness (AHR) to acetyl-β-methylcholine chloride, lung hyperpermeability, airway epithelial cell desquamation, and lung inflammation. Accordingly, we quantified sequelae of non-atopic asthma in wild-type mice and mice incapable of expressing CMKLR1 (CMKLR1-deficient mice) following cessation of acute inhalation exposure to either filtered room air (air) or ozone (O3), a criteria pollutant and non-atopic asthma stimulus. Following exposure to air, lung elastic recoil and airway responsiveness were greater while the quantity of adiponectin, a multi-functional adipocytokine, in bronchoalveolar lavage (BAL) fluid was lower in CMKLR1-deficient as compared to wild-type mice. Regardless of genotype, exposure to O3 caused AHR, lung hyperpermeability, airway epithelial cell desquamation, and lung inflammation. Nevertheless, except for minimal genotype-related effects on lung hyperpermeability and BAL adiponectin, we observed no other genotype-related differences following O3 exposure. In summary, we demonstrate that CMKLR1 limits the severity of innate airway responsiveness and lung elastic recoil but has a nominal effect on lung pathophysiology induced by acute exposure to O3.

Effects of nicotine on microRNA-124 expression in bile duct ligation-induced liver fibrosis in rats

BACKGROUND

Nicotine, the main compound of smoking may exert its effects by changing the expression of microRNAs (miRNAs). This study was conducted to further investigate the molecular mechanisms of miRNA-dependent effects of nicotine in an animal model of liver fibrosis.

METHODS

The bile duct ligation (BDL) approach was used to create a model of liver fibrosis. Twenty-four male Wistar rats were used in the study. The effects of nicotine administration on miRNA-124 expression, as well as alpha-smooth muscle actin (liver fibrosis marker) and chemokine ligand 2 (an inflammatory chemokine), were investigated using RT-qPCR. In addition, the mRNA and protein expression of signal transducer and activator of transcription 3 (STAT-3; as a potential target for miRNA-124) were investigated by RT-qPCR and immunofluorescence, respectively. Liver enzyme activity levels were measured using a colorimetric assay. In addition, the effects of nicotine on the process of liver fibrosis were investigated with histological studies.

RESULTS

The development of liver fibrosis in BDL rats and nicotine administration led to a decrease in miRNA-124 expression. The decrease in the expression is accompanied by the increase in the expression of fibrotic and proinflammatory genes. Also, an increase in STAT-3 mRNA and protein expression was observed in the fibrotic rats that received nicotine. In addition, the significant increase in bilirubin and liver enzymes in fibrotic rats worsens with nicotine administration. The results of histological studies also confirm these results.

CONCLUSION

Considering that miRNA-124 is an anti-inflammatory miRNA, it can be concluded that the decrease in its expression due to nicotine exposure leads to an increase in inflammatory processes and subsequently to an increase in liver fibrosis.

Tumor-associated macrophage (TAM)-secreted CCL22 confers cisplatin resistance of esophageal squamous cell carcinoma (ESCC) cells via regulating the activity of diacylglycerol kinase α (DGKα)/NOX4 axis

Tumor-associated macrophages (TAMs) are often associated with chemoresistance and resultant poor clinical outcome in solid tumors. Here, we demonstrated that TAMs-released chemokine-C-C motif chemokine 22 (CCL22) in esophageal squamous cell carcinoma (ESCC) stroma was tightly correlated with the chemoresistance of ESCC patients. TAMs-secreted CCL22 was able to block the growth inhibitory and apoptosis-promoting effects of cisplatin on ESCC cells. Mechanistically, CCL22 stimulated intratumoral diacylglycerol kinase α (DGKα) to produce phosphatidic acid (PA), which suppressed the activity of NADPH oxidase 4 (NOX4) and then blocked the overproduction of intratumoral reactive species oxygen (ROS) induced by cisplatin. CCL22 activated DGKα/nuclear factor-κB (NF-κB) axis to upregulate the level of several members of ATP binding cassette (ABC) transporter superfamily, including ABC sub-family G member 4 (ABCG4), ABC sub-family A member 3 (ABCA3), and ABC sub-family A member 5 (ABCA5), to lower the intratumoral concentration of cisplatin. Consequently, these processes induced the cisplatin resistance in ESCC cells. In xenografted models, targeting DGKα with 5'-cholesterol-conjugated small-interfering (si) RNA enhanced the chemosensitivity of cisplatin in ESCC treatment, especially in the context of TAMs. Our data establish the correlation between the TAMs-induced intratumoral metabolic product/ROS axis and chemotherapy efficacy in ESCC treatment and reveal relevant molecular mechanisms.

The inhibitory effect of DIF-3 on polyinosinic-polycytidylic acid-induced innate immunity activation in human cerebral microvascular endothelial cells

For the treatment and prevention of autoinflammatory diseases, it is essential to develop the drug, regulating the innate immune system. Although differentiation-inducing factor (DIF) derivatives, extracted from the cellular slime mold, Dictyostelium discoideum, exhibit immunomodulatory effects, their effects on the regulation of innate immunity in brain are unknown. In this study, we used the human cerebral microvascular endothelial cell line, hCMEC/D3, to investigate the effects of DIF derivatives on the generation of C-X-C motif chemokine (CXCL) 10 and interferon (IFN)-β induced by polyinosinic-polycytidylic acid (poly IC). DIF-3 (1-10 μM), but not DIF-1 and DIF-2, dose-dependently inhibited the biosynthesis of not only CXCL10 but also CXCL16 and C-C motif chemokine 2 induced by poly IC. DIF-3 also strongly decreased IFN-β mRNA expression and protein release from the cells induced by poly IC through the prohibition of p65, a subtype of NF-ĸB, not interferon regulatory transcription factor 3 phosphorylation. In the docking simulation study, we confirmed that DIF-3 had a high affinity to p65. These results suggest that DIF-3 regulates the innate immune system by inhibiting TLR3/IFN-β signaling axis through the NF-ĸB phosphorylation inhibition.

Lactobacillus rhamnosus dampens cytokine and chemokine secretion from primary human nasal epithelial cells infected with rhinovirus

AIMS

To investigate the effect of Lactobacillus rhamnosus on viral replication and cellular response to human rhinovirus (HRV) infection, including the secretion of antiviral and inflammatory mediators from well-differentiated nasal epithelial cells (WD-NECs).

METHODS AND RESULTS

The WD-NECs from healthy adult donors (N = 6) were cultured in vitro, exposed to different strains of L. rhamnosus (D3189, D3160, or LB21), and infected with HRV (RV-A16) after 24 h. Survival and adherence capacity of L. rhamnosus in a NEC environment were confirmed using CFSE-labelled isolates, immunofluorescent staining, and confocal microscopy. Shed virus and viral replication were quantified using TCID50 assays and RT-qPCR, respectively. Cytotoxicity was measured by lactate dehydrogenase (LDH) activity. Pro-inflammatory mediators were measured by multiplex immunoassay, and interferon (IFN)-λ1/3 was measured using a standard ELISA kit. Lactobacillus rhamnosus was able to adhere to and colonize WD-NECs prior to the RV-A16 infection. Lactobacillus rhamnosus did not affect shed RV-A16, viral replication, RV-A16-induced IFN-λ1/3 production, or LDH release. Pre-exposure to L. rhamnosus, particularly D3189, reduced the secretion of RV-A16-induced pro-inflammatory mediators by WD-NECs.

CONCLUSIONS

These findings demonstrate that L. rhamnosus differentially modulates RV-A16-induced innate inflammatory immune responses in primary NECs from healthy adults.

Chemokine N-terminal-derived peptides differentially regulate signaling by the receptors CCR1 and CCR5

Inflammatory chemokines are often elevated in disease settings, where the largest group of CC-chemokines are the macrophage inflammatory proteins (MIP), which are promiscuous for the receptors CCR1 and CCR5. MIP chemokines, such as CCL3 and CCL5 are processed at the N terminus, which influences signaling in a highly diverse manner. Here, we investigate the signaling capacity of peptides corresponding to truncated N termini. These 3-10-residue peptides displayed weak potency but, surprisingly, retained their signaling on CCR1. In contrast, none of the peptides generated a signal on CCR5, but a CCL3-derived tetrapeptide was a positive modulator boosting the signal of several chemokine variants on CCR5. In conclusion, chemokine N termini can be mimicked to produce small CCR1-selective agonists, as well as CCR5-selective modulators.

Aconite aqueous extract inhibits the growth of hepatocellular carcinoma through CCL2-dependent enhancement of natural killer cell infiltration

OBJECTIVE

Aconite is a traditional Chinese herbal medicine that has been found to inhibit the development of liver cancer; however, its exact molecular mechanisms in this process remain unclear. This study explores how aconite aqueous extract (AAE) inhibits hepatocellular carcinoma (HCC).

METHODS

An in vivo mouse model of subcutaneous liver cancer was established. After AAE treatment, immunohistochemistry (IHC) was used to determine the effect of AAE on natural killer (NK) cells. Subsequently, C57BL/6 mice were used to establish the subcutaneous tumor model, and a group of these mice were treated with anti-PK163 antibody to remove NK cells, which was verified by flow cytometry and IHC. The effect of AAE on the proliferation of HCC cells in vitro was determined using cell counting kit-8. The effect of AAE on chemokine production in HCC cells was measured using real-time quantitative polymerase chain reaction and an enzyme-linked immunosorbent assay. The effect of AAE on the migration of NK cells was determined using a transwell assay. Finally, the molecular mechanism was investigated using the Western blotting method.

RESULTS

We demonstrated that the ability of AAE to induce overexpression of the cytokine C-C motif chemokine ligand 2 (CCL2) in HCC cells is fundamental to the infiltration of NK cells into the tumor bed. Mechanistically, we found that the upregulation of CCL2 was achieved by the activation of c-Jun N-terminal kinase but not extracellular regulated protein kinase or p38.

CONCLUSION

Our findings suggest that AAE can be used as an effective immune adjuvant to enhance antitumor immunity by increasing NK cell infiltration into tumors, which could help to improve the efficacy of HCC treatments. Please cite this article as: Yang KD, Zhang X, Shao MC, Wang LN. Aconite aqueous extract inhibits the growth of hepatocellular carcinoma through CCL2-dependent enhancement of natural killer cell infiltration. J Integr Med. 2023; 21(6): 575-583.

Tumor-Derived CCL5 Recruits Cancer-Associated Fibroblasts and Promotes Tumor Cell Proliferation in Esophageal Squamous Cell Carcinoma

Cancer-associated fibroblasts (CAF) can promote tumor growth, metastasis, and therapeutic resistance in esophageal squamous cell carcinoma (ESCC), but the mechanisms of action remain elusive. Our objective was to identify secreted factor(s) that mediate the communication between CAFs and ESCC tumor cells with the aim of identifying potential druggable targets. Through unbiased cytokine arrays, we have identified CC motif chemokine ligand 5 (CCL5) as a secreted factor that is increased upon co-culture of ESCC cells and CAFs, which we replicated in esophageal adenocarcinoma (EAC) with CAFs. Loss of tumor-cell-derived CCL5 reduces ESCC cell proliferation in vitro and in vivo and we propose this is mediated, in part, by a reduction in ERK1/2 signaling. Loss of tumor-derived CCL5 reduces the percentage of CAFs recruited to xenograft tumors in vivo. CCL5 is a ligand for the CC motif receptor 5 (CCR5), for which a clinically approved inhibitor exists, namely Maraviroc. Maraviroc treatment reduced tumor volume, CAF recruitment, and ERK1/2 signaling in vivo, thus, mimicking the effects observed with genetic loss of CCL5. High CCL5 or CCR5 expression is associated with worse prognosis in low-grade esophageal carcinomas.

IMPLICATIONS

These data highlight the role of CCL5 in tumorigenesis and the therapeutic potential of targeting the CCL5-CCR5 axis in ESCC.

Thymoquinone Inhibition of Chemokines in TNF-α-Induced Inflammatory and Metastatic Effects in Triple-Negative Breast Cancer Cells

The lack of identifiable molecular targets or biomarkers hinders the development of treatment options in triple-negative breast cancer (TNBC). However, natural products offer a promising alternative by targeting inflammatory chemokines in the tumor microenvironment (TME). Chemokines are crucial in promoting breast cancer growth and metastasis and correlate to the altered inflammatory process. In the present study, we evaluated the anti-inflammatory and antimetastatic effects of the natural product thymoquinone (TQ) on TNF-α-stimulated TNBC cells (MDA-MB-231 and MDA-MB-468) to study the cytotoxic, antiproliferative, anticolony, antimigratory, and antichemokine effects using enzyme-linked immunosorbent assays, quantitative real-time reverse transcription-polymerase chain reactions, and Western blots were used in sequence to validate the microarray results further. Four downregulated inflammatory cytokines were identified, CCL2 and CCL20 in MDA-MB-468 cells and CCL3 and CCL4 in MDA-MB-231 cells. Furthermore, when TNF-α-stimulated MDA-MB-231 cells were compared with MDA-MB-468 cells, the two cells were sensitive to TQ's antichemokine and antimetastatic effect in preventing cell migration. It was concluded from this investigation that genetically different cell lines may respond to TQ differently, as TQ targets CCL3 and CCL4 in MDA-MB-231 cells and CCL2 and CCL20 in MDA-MB-468 cells. Therefore, the results indicate that TQ may be recommended as a component of the therapeutic strategy for TNBC treatment. These outcomes stem from the compound's capacity to suppress the chemokine. Even though these findings support the usage of TQ as part of a therapy strategy for TNBC associated with the identified chemokine dysregulations, additional in vivo studies are needed to confirm these in vitro results.

Tumor microenvironment signaling and therapeutics in cancer progression

Tumor development and metastasis are facilitated by the complex interactions between cancer cells and their microenvironment, which comprises stromal cells and extracellular matrix (ECM) components, among other factors. Stromal cells can adopt new phenotypes to promote tumor cell invasion. A deep understanding of the signaling pathways involved in cell-to-cell and cell-to-ECM interactions is needed to design effective intervention strategies that might interrupt these interactions. In this review, we describe the tumor microenvironment (TME) components and associated therapeutics. We discuss the clinical advances in the prevalent and newly discovered signaling pathways in the TME, the immune checkpoints and immunosuppressive chemokines, and currently used inhibitors targeting these pathways. These include both intrinsic and non-autonomous tumor cell signaling pathways in the TME: protein kinase C (PKC) signaling, Notch, and transforming growth factor (TGF-β) signaling, Endoplasmic Reticulum (ER) stress response, lactate signaling, Metabolic reprogramming, cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) and Siglec signaling pathways. We also discuss the recent advances in Programmed Cell Death Protein 1 (PD-1), Cytotoxic T-Lymphocyte Associated Protein 4 (CTLA4), T-cell immunoglobulin mucin-3 (TIM-3) and Lymphocyte Activating Gene 3 (LAG3) immune checkpoint inhibitors along with the C-C chemokine receptor 4 (CCR4)- C-C class chemokines 22 (CCL22)/ and 17 (CCL17), C-C chemokine receptor type 2 (CCR2)- chemokine (C-C motif) ligand 2 (CCL2), C-C chemokine receptor type 5 (CCR5)- chemokine (C-C motif) ligand 3 (CCL3) chemokine signaling axis in the TME. In addition, this review provides a holistic understanding of the TME as we discuss the three-dimensional and microfluidic models of the TME, which are believed to recapitulate the original characteristics of the patient tumor and hence may be used as a platform to study new mechanisms and screen for various anti-cancer therapies. We further discuss the systemic influences of gut microbiota in TME reprogramming and treatment response. Overall, this review provides a comprehensive analysis of the diverse and most critical signaling pathways in the TME, highlighting the associated newest and critical preclinical and clinical studies along with their underlying biology. We highlight the importance of the most recent technologies of microfluidics and lab-on-chip models for TME research and also present an overview of extrinsic factors, such as the inhabitant human microbiome, which have the potential to modulate TME biology and drug responses.

Wound healing by transplantation of mesenchymal stromal cells loaded on polyethylene terephthalate scaffold: Implications for skin injury treatment

BACKGROUND

Several clinical studies have shown that cellular therapy based on mesenchymal stromal cells (MSCs) transplantation may accelerate wound healing. One major challenge is the delivery system used for MSCs transplantation. In this work, we evaluated the capacity of a scaffold based on polyethylene terephthalate (PET) to maintain the viability and biological functions of MSCs, in vitro. We examined the capacity of MSCs loaded on PET (MSCs/PET) to induce wound healing in an experimental model of full-thickness wound.

METHODS

Human MSCs were seeded and cultured on PET membranes at 37 °C for 48 h. Adhesion, viability, proliferation, migration, multipotential differentiation and chemokine production were evaluated in cultures of MSCs/PET. The possible therapeutic effect of MSCs/PET on the re-epithelialization of full thickness wounds was examined at day 3 post-wounding in C57BL/6 mice. Histological and immunohistochemical (IH) studies were performed to evaluate wound re-epithelialization and the presence of epithelial progenitor cells (EPC). As controls, wounds without treatment or treated with PET were established.

RESULTS

We observed MSCs adhered to PET membranes and maintained their viability, proliferation and migration. They preserved their multipotential capacity of differentiation and ability of chemokine production. MSCs/PET implants promoted an accelerated wound re-epithelialization, after three days post-wounding. It was associated with the presence of EPC Lgr6⁺ and K6⁺.

DISCUSSION

Our results show that MSCs/PET implants induce a rapid re-epithelialization of deep- and full-thickness wounds. MSCs/PET implants constitute a potential clinical therapy for treating cutaneous wounds.

Trichosanthin Promotes Anti-Tumor Immunity through Mediating Chemokines and Granzyme B Secretion in Hepatocellular Carcinoma

Trichosanthin (TCS) is a type I ribosome-inactivating protein extracted from the tuberous root of the plant Trichosanthes. TCS shows promising potential in clinical drug abortion, anti-tumor and immunological regulation. However, the molecular mechanisms of its anti-tumor and immune regulation properties are still not well discovered. In the present study, we investigated the anti-tumor activity of TCS in hepatocellular carcinoma (HCC), both in vitro and in vivo. Both HCC cell lines and xenograft tumor tissues showed considerable growth inhibition after they were treated with TCS. TCS provoked caspase-mediated apoptosis in HCC cells and xenograft tumor tissues. The recruitment of CD8⁺ T cells to HCC tissues and the expression of chemokines, CCL2 and CCL22, were promoted upon TCS treatment. In addition, TCS induced an upregulation of Granzyme B (GrzB), TNF-α and IFN-γ in HCC tissues, which are the major cytotoxic mediators produced by T cells. Furthermore, TCS also resulted in an increase of mannose-6-phosphate receptor (M6PR), the major receptor of GrzB, in HCC tissues. In summary, these results suggest that TCS perhaps increases T-cell immunity via promoting the secretion of chemokines and accelerating the entry of GrzB to HCC cells, which highlights the potential role of TCS in anti-tumor immunotherapy.

On-Chip Organoid Formation to Study CXCR4/CXCL-12 Chemokine Microenvironment Responses for Renal Cancer Drug Testing

Organoid models have gained importance in recent years in determining the toxic effects of drugs in cancer studies. Organoid designs with the same standardized size and cellular structures are desired for drug tests. The field of microfluidics offers numerous advantages to enable well-controlled and contamination-free biomedical research. In this study, simple and low-cost microfluidic devices were designed and fabricated to develop an organoid model for drug testing for renal cancers. Caki human renal cancer cells and mesenchymal stem cells isolated from human umbilical cord were placed into alginate hydrogels. The microfluidic system was implemented to form size-controllable organoids within alginate hydrogels. Alginate capsules of uniform sizes formed in the microfluidic system were kept in cell culture for 21 days, and their organoid development was studied with calcein staining. Cisplatin was used as a standard chemotherapeutic, and organoid sphere structures were examined as a function of time with an MTT assay. HIF-1α, CXCR4 and CXCL-12 chemokine protein, and CXCR4 and CXCL-12 gene levels were tested in organoids and cisplatin responses. In conclusion, it was found that the standard renal cancer organoids made on a lab-on-a-chip system can be used to measure drug effects and tumor microenvironment responses.

Emerging role of chemokines in small cell lung cancer: Road signs for metastasis, heterogeneity, and immune response

Small cell lung cancer (SCLC) is a recalcitrant, relatively immune-cold, and deadly subtype of lung cancer. SCLC has been viewed as a single or homogenous disease that includes deletion or inactivation of the two major tumor suppressor genes (TP53 and RB1) as a key hallmark. However, recent sightings suggest the complexity of SCLC tumors that comprises highly dynamic multiple subtypes contributing to high intratumor heterogeneity. Furthermore, the absence of targeted therapies, the understudied tumor immune microenvironment (TIME), and subtype plasticity are also responsible for therapy resistance. Secretory chemokines play a crucial role in immunomodulation by trafficking immune cells to the tumors. Chemokines and cytokines modulate the anti-tumor immune response and wield a pro-/anti-tumorigenic effect on SCLC cells after binding to cognate receptors. In this review, we summarize and highlight recent findings that establish the role of chemokines in SCLC growth and metastasis, and sophisticated intratumor heterogeneity. We also discuss the chemokine networks that are putative targets or modulators for augmenting the anti-tumor immune responses in targeted or chemo-/immuno-therapeutic strategies, and how these combinations may be utilized to conquer SCLC.

Cadmium exposure induces pyroptosis in testicular tissue by increasing oxidative stress and activating the AIM2 inflammasome pathway

High doses of cadmium (Cd) cause irreversible injury to the reproductive system, especially testicular tissue. Studies have shown that pyroptosis is involved in Cd-induced tissue damage, but whether pyroptosis is involved in damage to testicular tissue following Cd exposure remains unclear. To investigate the mechanism of pyroptosis in testicular injury induced by Cd exposure, we used 8-week-old male C57BL/6J mice subjected to consecutive 7 days of intraperitoneal injection of cadmium chloride (CdCl₂) at concentrations of 0, 1.0 and 3.0 mg/kg. The results indicated that 3.0 mg/kg CdCl₂ significantly decreased serum testosterone levels, sperm concentration and sperm motility, while increased LDH and IL-1β levels. Testicular HE staining indicated that Cd exposure damaged the interstitial cells and increased the atypical residual bodies. Fluorescence results indicated that 3.0 mg/kg CdCl₂ increased ROS levels, DNA damage, and the number of TUNEL-positive seminiferous tubule cells in testicular tissue. Transcriptome analysis showed that Cd exposure mainly induced inflammatory and chemokine signaling pathways in testicular tissue, with upregulated mRNA levels of Aim2, and reduced mRNA levels of Nlrp3. Further analysis showed that 3.0 mg/kg CdCl₂ increased the expression of testicular HO-1, SOD2, γH2AX and PARP-1, as well as the pyroptosis-related factors GSDMD, GSDME, Caspase-1, ASC and IL-1β. In conclusion, our results provide a possible mechanism by which Cd exposure activates the AIM2 pathway by increasing oxidative stress injury to induce pyroptosis in testicular tissue. This provides a new perspective on testicular damage caused by Cd exposure.

Inhibition of human macrophage activation via pregnane neurosteroid interactions with toll-like receptors: Sex differences and structural requirements

We recently discovered that (3α,5α)3-hydroxypregnan-20-one (allopregnanolone) inhibits pro-inflammatory toll-like receptor (TLR) activation and cytokine/chemokine production in mouse macrophage RAW264.7 cells. The present studies evaluate neurosteroid actions upon TLR activation in human macrophages from male and female healthy donors. Buffy coat leukocytes were obtained from donors at the New York Blood Center (http://nybloodcenter.org/), and peripheral blood mononuclear cells were isolated and cultured to achieve macrophage differentiation. TLR4 and TLR7 were activated by lipopolysaccharide (LPS) or imiquimod in the presence/absence of allopregnanolone or related neurosteroids and pro-inflammatory markers were detected by ELISA or western blotting. Cultured human monocyte-derived-macrophages exhibited typical morphology, a mixed immune profile of both inflammatory and anti-inflammatory markers, with no sex difference at baseline. Allopregnanolone inhibited TLR4 activation in male and female donors, preventing LPS-induced elevations of TNF-α, MCP-1, pCREB and pSTAT1. In contrast, 3α,5α-THDOC and SGE-516 inhibited the TLR4 pathway activation in female, but not male donors. Allopregnanolone completely inhibited TLR7 activation by imiquimod, blocking IL-1-β, IL-6, pSTAT1 and pIRF7 elevations in females only. 3α,5α-THDOC and SGE-516 partially inhibited TLR7 activation, only in female donors. The results indicate that allopregnanolone inhibits TLR4 and TLR7 activation in cultured human macrophages resulting in diminished cytokine/chemokine production. Allopregnanolone inhibition of TLR4 activation was found in males and females, but inhibition of TLR7 signals exhibited specificity for female donors. 3α,5α-THDOC and SGE-516 inhibited TLR4 and TLR7 pathways only in females. These studies demonstrate anti-inflammatory effects of allopregnanolone in human macrophages for the first time and suggest that inhibition of pro-inflammatory cytokines/chemokines may contribute to its therapeutic actions.

Phloretin Protects Bovine Rumen Epithelial Cells from LPS-Induced Injury

Lipopolysaccharide (LPS) is an endotoxin that induces immune and inflammatory responses in the rumen epithelium of dairy cows. It is well-known that flavonoid phloretin (PT) exhibits anti-oxidative, anti-inflammatory and antibacterial activity. The aim of this research was to explore whether PT could decrease LPS-induced damage to bovine rumen epithelial cells (BRECs) and its molecular mechanisms of potential protective efficacy. BRECs were pretreated with PT for 2 h and then stimulated with LPS for the assessment of various response indicators. The results showed that 100 µM PT had no significant effect on the viability of 10 µg/mL LPS-induced BRECs, and this dose was used in follow-up studies. The results showed that PT pre-relieved the decline in LPS-induced antioxidant indicators (T-AOC and GSH-PX). PT pretreatment resulted in decreased interleukin-1β (IL-1β), IL-6, IL-8, tumor necrosis factor-α (TNF-α) and chemokines (CCL2, CCL5, CCL20) expression. The underlying mechanisms explored reveal that PT may contribute to inflammatory responses by regulating Toll-like receptor 4 (TLR4), nuclear transcription factor-κB p65 (NF-κB p65), and ERK1/2 (p42/44) signaling pathways. Moreover, further studies found that LPS-induced BRECs showed decreased expression of claudin-related genes (ZO-1, Occludin); these were attenuated by pretreatment with PT. These results suggest that PT enhances the antioxidant properties of BRECs during inflammation, reduces gene expression of pro-inflammatory cytokines and chemokines, and enhances barrier function. Overall, the results suggest that PT (at least in vitro) offers some protective effect against LPS-induced ruminal epithelial inflammation. Further in vivo studies should be conducted to identify strategies for the prevention and amelioration of short acute rumen acidosis (SARA) in dairy cows using PT.

Chemerin-9 stimulates migration in rat cardiac fibroblasts in vitro

Since chemerin is an adipocytokine whose concentration in blood increases in the subjects with various cardiac diseases, chemerin may be involved in pathogenesis of cardiac diseases. In the present study, we examined the effects of chemerin-9, an active fragment of chemerin, on functions of cardiac fibroblasts, which are involved in pathophysiology of cardiac diseases. Primary cardiac fibroblasts were enzymatically isolated from adult male Wistar rats. Migration of cardiac fibroblasts was measured by a Boyden chamber assay and a scratch assay. Phosphorylation of Akt and extracellular signal-regulated kinase (ERK) was measured by Western blotting. Reactive oxygen species (ROS) production was measured by 2',7'-dichlorodihydrofluoresein staining. Chemerin-9 significantly stimulated migration in cardiac fibroblasts. Chemerin-9 significantly stimulated phosphorylation of Akt and ERK as well as ROS production. An Akt pathway inhibitor, LY294002, an ERK pathway inhibitor, PD98059, an antagonist of chemokine-like receptor 1 (CMKLR1), 2-(α-Napththoyl) ethyltrimethylammonium iodide, or an antioxidant, N-acetyl-L-cysteine prevented the migration induced by chemerin-9. In summary, we for the first time revealed that chemerin-9 stimulates migration perhaps through the ROS-dependent activation of Akt and ERK via CMKLR1 in cardiac fibroblasts. It is proposed that chemerin plays a role in the pathogenesis of cardiac diseases.

Neuroprotective Effects of Chemerin on a Mouse Stroke Model: Behavioral and Molecular Dimensions

The present study was conducted to investigate the effects of different doses of recombinant human Chemerin (rhChemerin) on brain damage, spatial memory, blood-brain barrier (BBB) disruption and cellular and molecular mechanisms in a mouse stroke model. The mouse stroke model was developed by blocking the middle cerebral artery for 1 h and performing reperfusion for 23 h. Immediately, one and three hours after the stroke, 200, 400 and 800 ng/mouse of intranasal rhChemerin was administered. Neuronal and BBB damage, spatial memory and neurological performance were examined 24 h after the stroke. Western blotting and immunofluorescence were utilized to determine the effects of rhChemerin on the expressions of nuclear factor kappa B (NF-κB), pro-inflammatory cytokines such as TNF-α and IL-1β, anti-inflammatory cytokines such as IL-10 and TGF-β and vascular endothelial growth factor (VEGF). Administering 400 and 800 ng/mouse of rhChemerin in the mice immediately and one hour after ischemia minimized the infarct size, BBB opening, spatial memory and neurological impairment (P < 0.001). Furthermore, 800 ng/mouse of rhChemerin significantly diminished terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive (apoptotic) cells, suppressed the expressions of NF-kB, TNF-α and IL-1β and upregulated IL-10 and VEGF in the cortex and hippocampus of the mice. The present findings showed that rhChemerin administered immediately and one hour after stroke alleviates neuronal and BBB injures and improves spatial memory. These effects of rhChemerin may be mediated by inhibiting inflammatory pathways and apoptotic machinery.

Chemerin impairs food intake and body weight in chicken: Focus on hypothalamic neuropeptides gene expression and AMPK signaling pathway

Unlike mammals, the role of adipokines and more particularly of chemerin in the regulation of food intake is totally unknown in avian species. Here we investigated the effect of chemerin on the food and water consumption and on the body weight in chicken. We studied the effects on the plasma glucose and insulin concentrations and the hypothalamic neuropeptides and AMPK signaling pathway. Female broiler chickens were intraperitoneally injected, daily for 13 days with either vehicle (saline; n = 25) or chemerin (8 μg/kg; n = 25 and 16 μg/kg; n = 25). Food and water intakes were recorded 24 h after each administration. Overnight fasted animals were sacrificed at day 13 (D13), 24 h after the last injection and hypothalamus and left cerebral hemispheres were collected. Chemerin and its receptors protein levels were determined by western-blot. Gene expression of neuropeptide Y (Npy), agouti-related peptide (Agrp), corticotrophin releasing hormone (Crh), pro-opiomelanocortin (Pomc), cocaine and amphetamine-regulated transcript (Cart) and Taste 1 Receptor Member 1 (Tas1r1) were evaluated by RT-qPCR. In chicken, we found that the protein amount of chemerin, CCRL2 and GPR1 was similar in left cerebral hemisphere and hypothalamus whereas CMKLR1 was higher in hypothalamus. Chemerin administration (8 and 16 μg/kg) decreased both food intake and body weight compared to vehicle without affecting water intake and the size or volume of different brain subdivisions as determined by magnetic resonance imaging. It also increased plasma insulin levels whereas glucose levels were decreased. These data were associated with an increase in Npy and Agrp expressions and a decrease in Crh, Tas1r1 mRNA expression within the hypothalamus. Furthermore, chemerin decreased hypothalamic CMKLR1 protein expression and AMPK activation. Taken together, these results support that chemerin could be a peripheral appetite-regulating signal through modulation of hypothalamic peptides expression in chicken.

Functional Assessment of Intestinal Permeability and Neutrophil Transepithelial Migration in Mice using a Standardized Intestinal Loop Model

The intestinal mucosa is lined by a single layer of epithelial cells that forms a dynamic barrier allowing paracellular transport of nutrients and water while preventing passage of luminal bacteria and exogenous substances. A breach of this layer results in increased permeability to luminal contents and recruitment of immune cells, both of which are hallmarks of pathologic states in the gut including inflammatory bowel disease (IBD). Mechanisms regulating epithelial barrier function and transepithelial migration (TEpM) of polymorphonuclear neutrophils (PMN) are incompletely understood due to the lack of experimental in vivo methods allowing quantitative analyses. Here, we describe a robust murine experimental model that employs an exteriorized intestinal segment of either ileum or proximal colon. The exteriorized intestinal loop (iLoop) is fully vascularized and offers physiological advantages over ex vivo chamber-based approaches commonly used to study permeability and PMN migration across epithelial cell monolayers. We demonstrate two applications of this model in detail: (1) quantitative measurement of intestinal permeability through detection of fluorescence-labeled dextrans in serum after intraluminal injection, (2) quantitative assessment of migrated PMN across the intestinal epithelium into the gut lumen after intraluminal introduction of chemoattractants. We demonstrate feasibility of this model and provide results utilizing the iLoop in mice lacking the epithelial tight junction-associated protein JAM-A compared to controls. JAM-A has been shown to regulate epithelial barrier function as well as PMN TEpM during inflammatory responses. Our results using the iLoop confirm previous studies and highlight the importance of JAM-A in regulation of intestinal permeability and PMN TEpM in vivo during homeostasis and disease. The iLoop model provides a highly standardized method for reproducible in vivo studies of intestinal homeostasis and inflammation and will significantly enhance understanding of intestinal barrier function and mucosal inflammation in diseases such as IBD.

Modulatory effect of chemokines on porcine endometrial stromal and endothelial cells

The endometrium undergoes cyclical changes during the estrous cycle and pregnancy. These alterations are controlled by various factors, including cytokines. The present study aimed to screen the effect of several chemokines (CCL2, CCL4, CCL5, CCL8, CXCL2, CXCL8, CXCL9, CXCL10, and CXCL12) on endometrial stromal and endothelial cells. Real-time PCR analysis revealed mRNA expression of all examined chemokines and their receptors in primary stromal cells and undetectable levels of CXCL9, CXCL10, and CXCR3 in endothelial cells. Immunocytochemical staining showed variable distribution of chemokine receptors in stromal and endothelial cells. All examined chemokines enhanced stromal cell proliferation, and CCL2 and CXCL12 also increased the migratory potential of these cells. The evaluation of a possible indirect effect of chemokines on angiogenesis and lymphangiogenesis demonstrated that CXCL12 may potentially negatively affect lymphatic vessel creation. Downregulation of VEGFC mRNA and protein expression was noticed after CXCL12 stimulation. Among all examined chemokines, CCL4 and CCL8 positively affected the proliferation and migration of endothelial cells. The number of capillary-like structures was significantly reduced after CXCL8, CXCL10, and CXCL12 stimulation. In conclusion, among all examined chemokines, CCL2 is thought to act as the modulator of stromal cell functions, whereas CCL4 and CCL8 are suggested to be potent factors directly stimulating blood vessel creation.

The TIPE Molecular Pilot That Directs Lymphocyte Migration in Health and Inflammation

Lymphocytes are some of the most motile cells of vertebrates, constantly navigating through various organ systems. Their specific positioning in the body is delicately controlled by site-specific directional cues such as chemokines. While it has long been suspected that an intrinsic molecular pilot, akin to a ship's pilot, guides lymphocyte navigation, the nature of this pilot is unknown. Here we show that the TIPE (TNF-α-induced protein 8-like) family of proteins pilot lymphocytes by steering them toward chemokines. TIPE proteins are carriers of lipid second messengers. They mediate chemokine-induced local generation of phosphoinositide second messengers, but inhibit global activation of the small GTPase Rac. TIPE-deficient T lymphocytes are completely pilot-less: they are unable to migrate toward chemokines despite their normal ability to move randomly. As a consequence, TIPE-deficient mice have a marked defect in positioning their T lymphocytes to various tissues, both at the steady-state and during inflammation. Thus, TIPE proteins pilot lymphocytes during migration and may be targeted for the treatment of lymphocyte-related disorders.

HCT-116 colorectal cancer cells secrete chemokines which induce chemoattraction and intracellular calcium mobilization in NK92 cells

We recently reported that pretreatment of IL-2 activated human natural killer (NK) cells with the drugs dimethyl fumarate (DMF) and monomethyl fumarate (MMF) upregulated the expression of surface chemokine receptor CCR10. Ligands for CCR10, namely CCL27 and CCL28, induced the chemotaxis of these cells. Here, we performed a bioinformatics analysis to see which chemokines might be expressed by the human HCT-116 colorectal cancer cells. We observed that, in addition to CCL27 and CCL28, HCT-116 colorectal cancer cells profoundly express CXCL16 which binds CXCR6. Consequently, NK92 cells were treated with DMF and MMF for 24 h to investigate in vitro chemotaxis towards CXCL16, CCL27, and CCL28. Furthermore, supernatants collected from HCT-116 cells after 24 or 48 h incubation induced the chemotaxis of NK92 cells. Similar to their effects on human IL-2-activated NK cells, MMF and DMF enhanced the expression of CCR10 and CXCR6 in NK92 cells. Neutralizing anti-CXCL16 or anti-CCL28 inhibited the chemotactic effects of 24 and 48 supernatants, whereas anti-CCL27 only inhibited the 48 h supernatant activity, suggesting that 24 h supernatant contains CXCL16 and CCL28, whereas HCT-116 secretes all three chemokines after 48 h in vitro cultures. CXCL16, CCL27, and CCL28, as well as the supernatants collected from HCT-116, induced the mobilization of (Ca)2+ in NK92 cells. Cross-desensitization experiments confirmed the results of the chemotaxis experiments. Finally, incubation of NK92 cells with HCT-116 induced the lysis of the tumor cells. In summary, these results might have important implications in directing the anti-tumor effectors NK cells towards tumor growth sites.

Influence of Chemokine N-Terminal Modification on Biased Agonism at the Chemokine Receptor CCR1

Leukocyte migration, a hallmark of the inflammatory response, is stimulated by the interactions between chemokines, which are expressed in injured or infected tissues, and chemokine receptors, which are G protein-coupled receptors (GPCRs) expressed in the leukocyte plasma membrane. One mechanism for the regulation of chemokine receptor signaling is biased agonism, the ability of different chemokine ligands to preferentially activate different intracellular signaling pathways via the same receptor. To identify features of chemokines that give rise to biased agonism, we studied the activation of the receptor CCR1 by the chemokines CCL7, CCL8, and CCL15(Δ26). We found that, compared to CCL15(Δ26), CCL7 and CCL8 exhibited biased agonism towards cAMP inhibition and away from β-Arrestin 2 recruitment. Moreover, N-terminal substitution of the CCL15(Δ26) N-terminus with that of CCL7 resulted in a chimera with similar biased agonism to CCL7. Similarly, N-terminal truncation of CCL15(Δ26) also resulted in signaling bias between cAMP inhibition and β-Arrestin 2 recruitment signals. These results show that the interactions of the chemokine N-terminal region with the receptor transmembrane region play a key role in selecting receptor conformations coupled to specific signaling pathways.

Chemokines Modulate Immune Surveillance in Tumorigenesis, Metastasis, and Response to Immunotherapy

Chemokines are small secreted proteins that orchestrate migration and positioning of immune cells within the tissues. Chemokines are essential for the function of the immune system. Accumulating evidence suggest that chemokines play important roles in tumor microenvironment. In this review we discuss an association of chemokine expression and activity within the tumor microenvironment with cancer outcome. We summarize regulation of immune cell recruitment into the tumor by chemokine-chemokine receptor interactions and describe evidence implicating chemokines in promotion of the "inflamed" immune-cell enriched tumor microenvironment. We review both tumor-promoting function of chemokines, such as regulation of tumor metastasis, and beneficial chemokine roles, including stimulation of anti-tumor immunity and response to immunotherapy. Finally, we discuss the therapeutic strategies target tumor-promoting chemokines or induce/deliver beneficial chemokines within the tumor focusing on pre-clinical studies and clinical trials going forward. The goal of this review is to provide insight into comprehensive role of chemokines and their receptors in tumor pathobiology and treatment.

Chemerin promotes angiogenesis in vivo

Chemerin acts as a chemotactic factor for leukocyte populations expressing the G protein-coupled receptor CMKLR1 (ChemR23). It is also an adipocytokine involved in obesity and metabolic syndromes. Previous studies have demonstrated that chemerin promotes angiogenesis in vitro, although the precise mechanism has not been elucidated. In this study, we have investigated whether chemerin regulates angiogenic processes and validated the associated mechanisms. In this study, chemerin stimulated angiogenesis in mice, which was demonstrated using Matrigel plug implantation assay, mouse corneal models of angiogenesis, and ex vivo rat aortic ring assay. To explore the mechanisms by which chemerin induced angiogenesis, we examined the effects of chemerin in human umbilical vein endothelium cells (HUVECs). Chemerin stimulated the differentiation of HUVECs into capillary-like structures, promoted the proliferation of HUVECs, and functioned as a chemoattractant in migration assays. Chemerin induced the phosphorylation of Akt and p42/44 extracellular signal-regulated kinase (ERK) in HUVECs and chemerin promotes angiogenesis via Akt and ERK. SiRNA against the chemerin receptor CMKLR1 but not that against another chemerin receptor, CCRL2, completely inhibited the chemerin-induced migration and angiogenesis of HUVECs, which indicates that chemerin promotes the migration and angiogenic activities of HUVECs mainly through CMKLR1.

The N-terminal polypeptide derived from vMIP-II exerts its anti-tumor activity in human breast cancer by regulating lncRNA SPRY4-IT1

Accumulating evidence demonstrates that long non-coding RNA (lncRNA) sprouty4-intron transcript 1 (lncRNA SPRY4-IT1) plays a vital role in the development of breast cancer. However, the underlying mechanism has not been eventually illuminated. We aimed to explore the biological activity of lncRNA SPRY4-IT1 in breast cancer cells and whether N-terminal polypeptide derived from viral macrophage inflammatory protein II (NT21MP) could exert its anti-tumor effect by regulating lncRNA SPRY4-IT1 and its target gene SKA2 Real-time RT-PCR, Western blotting, wound healing, and invasion assays were used to achieve this goal. We found that lncRNA SPRY4-IT1 was highly expressed in breast cancer cells. Moreover, NT21MP markedly inhibited biological effects of breast cancer cells by regulating lncRNA SPRY4-IT1, which was partially achieved through SKA2. Our findings suggested that lncRNA SPRY4-IT1 could serve as a novel biomarker by NT21MP for breast cancer.

Broad-Spectrum Inhibition of the CC-Chemokine Class Improves Wound Healing and Wound Angiogenesis

Angiogenesis is involved in the inflammation and proliferation stages of wound healing, to bring inflammatory cells to the wound and provide a microvascular network to maintain new tissue formation. An excess of inflammation, however, leads to prolonged wound healing and scar formation, often resulting in unfavourable outcomes such as amputation. CC-chemokines play key roles in the promotion of inflammation and inflammatory-driven angiogenesis. Therefore, inhibition of the CC-chemokine class may improve wound healing. We aimed to determine if the broad-spectrum CC-chemokine inhibitor “35K” could accelerate wound healing in vivo in mice. In a murine wound healing model, 35K protein or phosphate buffered saline (PBS, control) were added topically daily to wounds. Cohorts of mice were assessed in the early stages (four days post-wounding) and in the later stages of wound repair (10 and 21 days post-wounding). Topical application of the 35K protein inhibited CC-chemokine expression (CCL5, CCL2) in wounds and caused enhanced blood flow recovery and wound closure in early-mid stage wounds. In addition, 35K promoted neovascularisation in the early stages of wound repair. Furthermore, 35K treated wounds had significantly lower expression of the p65 subunit of NF-κB, a key inflammatory transcription factor, and augmented wound expression of the pro-angiogenic and pro-repair cytokine TGF-β. These findings show that broad-spectrum CC-chemokine inhibition may be beneficial for the promotion of wound healing.

Dynamic change in natural killer cell type in the human ocular mucosa in situ as means of immune evasion by adenovirus infection

The most severe form of virus-induced inflammation at the ocular surface is epidemic keratoconjunctivitis (EKC), often caused by group D human adenoviruses (HAdVs). We investigated the dynamics and mechanisms of changes in natural killer (NK) cell types in the human ocular mucosal surface in situ over the course of infection. In the acute phase of infection, the mature CD56(dim)NK cells that comprise a major subpopulation in the normal human conjunctiva are replaced by CD56(bright)NK cells recruited to the ocular surface by chemokines produced by the infected epithelium, and NKG2A-expressing CD56(dim) and CD56(bright) NK cells become the major subpopulations in severe inflammation. These NK cells attracted to the mucosal surface are however incapable of mounting a strong antiviral response because of upregulation of the inhibitory ligand human leukocyte antigen-E (HLA-E) on infected epithelium. Furthermore, group D HAdVs downregulate ligands for activating NK cell receptors, thus rendering even the mature NKG2A(-)NK cells unresponsive, an immune-escape mechanism distinct from other adenoviruses. Our findings imply that the EKC-causing group D HAdVs utilize these multiple pathways to inhibit antiviral NK cell responses in the initial stages of the infection.

Wiskott-Aldrich Syndrome Interacting Protein Deficiency Uncovers the Role of the Co-receptor CD19 as a Generic Hub for PI3 Kinase Signaling in B Cells

Humans with Wiskott-Aldrich syndrome display a progressive immunological disorder associated with compromised Wiskott-Aldrich Syndrome Interacting Protein (WIP) function. Mice deficient in WIP recapitulate such an immunodeficiency that has been attributed to T cell dysfunction; however, any contribution of B cells is as yet undefined. Here we have shown that WIP deficiency resulted in defects in B cell homing, chemotaxis, survival, and differentiation, ultimately leading to diminished germinal center formation and antibody production. Furthermore, in the absence of WIP, several receptors, namely the BCR, BAFFR, CXCR4, CXCR5, CD40, and TLR4, were impaired in promoting CD19 co-receptor activation and subsequent PI3 kinase (PI3K) signaling. The underlying mechanism was due to a distortion in the actin and tetraspanin networks that lead to altered CD19 cell surface dynamics. In conclusion, our findings suggest that, by regulating the cortical actin cytoskeleton, WIP influences the function of CD19 as a general hub for PI3K signaling.

Chemerin inhibition of myogenesis and induction of adipogenesis in C2C12 myoblasts

Chemerin is an adipocyte-secreted adipokine that regulates the differentiation and metabolism of adipose through auto-/paracrine signaling. Its function in the differentiation of multipotent myoblast cells has thus far received little attention. In this study, C2C12 myoblast cells were cultured in the medium with Chemerin, and the differentiation potential of C2C12 myoblasts was analyzed. The results showed that Chemerin increased ROS levels and TG content of C2C12 cells. At the same time, the mRNA expressions and protein concentrations of the adipogenic factors PPARγ, C/EBPα and UCP1 were up-regulated, while the muscle specific transcription factors MyoD, Myogenin and MyHC were decreased in cultured C2C12 cells. In conclusion, the adipokine Chemerin promoted the adipogenic differentiation potential and altered the fate of myoblast cells from myogenesis to adipogenesis, which contributed in part to the up-regulated adipocyte genes. Our study reveals the importance of functional Chemerin signaling in adipogenesis and in directing the differentiation of multipotent myoblast cells.

Oral supplementation of diabetic mice with propolis restores the proliferation capacity and chemotaxis of B and T lymphocytes towards CCL21 and CXCL12 by modulating the lipid profile, the pro-inflammatory cytokine levels and oxidative stress

BACKGROUND

Type 1 diabetes mellitus (T1D) is a chronic autoimmune disease caused by the selective destruction of pancreatic β cells, followed by hyperglycemia, oxidative stress and the subsequent extensive impairment of immune cell functions, a phenomenon responsible for the development of chronic diabetic complications. Propolis, a natural bee product that is extensively used in foods and beverages, significantly benefits human health. Specifically, propolis exerts antioxidant, anti-inflammatory and analgesic effects that may improve diabetic complications. To further elucidate the potential benefits of propolis, the present study investigated the effect of dietary supplementation with propolis on the plasma cytokine profiles, free radical levels, lipid profile and lymphocyte proliferation and chemotaxis in a streptozotocin (STZ)-induced type I diabetic mouse model.

METHODS

Thirty male mice were equally distributed into 3 experimental groups: group 1, non-diabetic control mice; group 2, diabetic mice; and group 3, diabetic mice supplemented daily with an ethanol-soluble derivative of propolis (100 mg/kg body weight) for 1 month.

RESULTS

First, the induction of diabetes in mice was associated with hyperglycemia and significant decreases in the insulin level and the lymphocyte count. In this context, diabetic mice exhibited severe diabetic complications, as demonstrated by a significant decrease in the levels of IL-2, IL-4 and IL-7, prolonged elevation of the levels of pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) and reactive oxygen species (ROS) and altered lipid profiles compared with control non-diabetic mice. Moreover, antigen stimulation of B and T lymphocytes markedly reduced the proliferative capacity and chemotaxis of these cells towards CCL21 and CXCL12 in diabetic mice compared with control mice. Interestingly, compared with diabetes induction alone, treatment of diabetic mice with propolis significantly restored the plasma cytokine and ROS levels and the lipid profile to nearly normal levels. Most importantly, compared with untreated diabetic mice, diabetic mice treated with propolis exhibited significantly enhanced lymphocyte proliferation and chemotaxis towards CCL21 and CXCL12.

CONCLUSION

Our findings reveal the potential immuno-modulatory effects of propolis, which acts as a natural antioxidant to enhance the function of immune cells during diabetes.

[Chemerin induces insulin resistance in C2C12 cells through nuclear factor-κB pathway-mediated inflammatory reaction]

OBJECTIVE

To explore the insulin resistance-inducing effect of chemerin on murine C2C12 myoblasts and the underlying molecular mechanism.

METHODS

Following 24-hour treatment with various concentrations of chemerin (0, 10, 100) ng/mL and 30-minute insulin stimulation in C2C12 cells, the glucose uptake was evaluated using a fluorescence microplate reader. ELISA was used to detect the levels of interleukin-6 (IL-6), IL-8 and tumor necrosis factor α (TNF-α) in culture fluid. In addition, the expression of nuclear factor κB (NF-κB) was determined by Western blotting. The underlying mechanism involved in chemerin-induced insulin resistance was evaluated with the precondition of NF-κB blocker pyrrolidine dithiocarbamate (PDTC).

RESULTS

Chemerin inhibited the glucose uptake of C2C12 cells in a dose-dependent manner, concomitant with the increases of IL-6, IL-8, TNF-α levels. Furthermore, chemerin stimulation improved the expression of NF-κB. However, pretreatment with NF-κB blocker PDTC significantly abated the inhibitory effect of chemerin on glucose uptake, and also obviously decreased the levels of IL-6, IL-8 and TNF-α induced by chemerin.

CONCLUSION

Chemerin might induce insulin resistance in C2C12 cells through NF-κB pathway-mediated inflammatory reaction.

Human Tfh and Tfr cells: identification and assessment of their migration potential

The ability of follicular T cells to migrate into B-cell follicles is central for them to participate in germinal center responses. The chemokine receptor CXCR5 is expressed by both Tfh and Tfr cells and is the defining marker for follicular T cells. In addition, Tfh and Tfr cells express additional chemokine receptors to enable them to interact with B cells and other cell types. CXCR5(+) Tfh and Tfr cells are divided into CCR7(+) perifollicular cells and CCR7(-) follicular cells. Most of the CXCR5(+) CCR7(-) Tfh cells reside in germinal centers and are called GC T cells. The methods to identify human Tfh and Tfr cell subsets based on chemokine receptors and other antigens and assess their migration potential are provided in this article.

Interference with glycosaminoglycan-chemokine interactions with a probe to alter leukocyte recruitment and inflammation in vivo

In vivo leukocyte recruitment is not fully understood and may result from interactions of chemokines with glycosaminoglycans/GAGs. We previously showed that chlorite-oxidized oxyamylose/COAM binds the neutrophil chemokine GCP-2/CXCL6. Here, mouse chemokine binding by COAM was studied systematically and binding affinities of chemokines to COAM versus GAGs were compared. COAM and heparan sulphate bound the mouse CXC chemokines KC/CXCL1, MIP-2/CXCL2, IP-10/CXCL10 and I-TAC/CXCL11 and the CC chemokine RANTES/CCL5 with affinities in the nanomolar range, whereas no binding interactions were observed for mouse MCP-1/CCL2, MIP-1α/CCL3 and MIP-1β/CCL4. The affinities of COAM-interacting chemokines were similar to or higher than those observed for heparan sulphate. Although COAM did not display chemotactic activity by itself, its co-administration with mouse GCP-2/CXCL6 and MIP-2/CXCL2 or its binding of endogenous chemokines resulted in fast and cooperative peritoneal neutrophil recruitment and in extravasation into the cremaster muscle invivo. These local GAG mimetic features by COAM within tissues superseded systemic effects and were sufficient and applicable to reduce LPS-induced liver-specific neutrophil recruitment and activation. COAM mimics glycosaminoglycans and is a nontoxic probe for the study of leukocyte recruitment and inflammation invivo.

Controlled intramyocardial release of engineered chemokines by biodegradable hydrogels as a treatment approach of myocardial infarction

Myocardial infarction (MI) induces a complex inflammatory immune response, followed by the remodelling of the heart muscle and scar formation. The rapid regeneration of the blood vessel network system by the attraction of hematopoietic stem cells is beneficial for heart function. Despite the important role of chemokines in these processes, their use in clinical practice has so far been limited by their limited availability over a long time-span in vivo. Here, a method is presented to increase physiological availability of chemokines at the site of injury over a defined time-span and simultaneously control their release using biodegradable hydrogels. Two different biodegradable hydrogels were implemented, a fast degradable hydrogel (FDH) for delivering Met-CCL5 over 24 hrs and a slow degradable hydrogel (SDH) for a gradual release of protease-resistant CXCL12 (S4V) over 4 weeks. We demonstrate that the time-controlled release using Met-CCL5-FDH and CXCL12 (S4V)-SDH suppressed initial neutrophil infiltration, promoted neovascularization and reduced apoptosis in the infarcted myocardium. Thus, we were able to significantly preserve the cardiac function after MI. This study demonstrates that time-controlled, biopolymer-mediated delivery of chemokines represents a novel and feasible strategy to support the endogenous reparatory mechanisms after MI and may compliment cell-based therapies.

Coactosin-like 1 antagonizes cofilin to promote lamellipodial protrusion at the immune synapse

Actin depolymerizing factor-homology (ADF-H) family proteins regulate actin filament dynamics at multiple cellular locations. Herein, we have investigated the function of the ADF-H family member coactosin-like 1 (COTL1) in the regulation of actin dynamics at the T cell immune synapse (IS). We initially identified COTL1 in a genetic screen to identify novel regulators of T cell activation, and subsequently found that it associates with F-actin and localizes at the IS in response to TCR+CD28 stimulation. Live cell microscopy showed that depletion of COTL1 protein impaired T cell spreading in response to TCR ligation and abrogated lamellipodial protrusion at the T cell – B cell contact site, producing only a band of F-actin. Significantly, re-expression of wild type COTL1, but not a mutant deficient in F-actin binding could rescue these defects. In addition, COTL1 depletion reduced T cell migration. In vitro studies showed that COTL1 and cofilin compete with each other for binding to F-actin, and COTL1 protects F-actin from cofilin-mediated depolymerization. While depletion of cofilin enhanced F-actin assembly and lamellipodial protrusion at the IS, concurrent depletion of both COTL1 and cofilin restored lamellipodia formation. Taken together, our results suggest that COTL1 regulates lamellipodia dynamics in part by protecting F-actin from cofilin-mediated disassembly.

The viral KSHV chemokine vMIP-II inhibits the migration of Naive and activated human NK cells by antagonizing two distinct chemokine receptors

Natural killer (NK) cells are innate immune cells able to rapidly kill virus-infected and tumor cells. Two NK cell populations are found in the blood; the majority (90%) expresses the CD16 receptor and also express the CD56 protein in intermediate levels (CD56^Dim CD16^Pos) while the remaining 10% are CD16 negative and express CD56 in high levels (CD56^Bright CD16^Neg). NK cells also reside in some tissues and traffic to various infected organs through the usage of different chemokines and chemokine receptors. Kaposi's sarcoma-associated herpesvirus (KSHV) is a human virus that has developed numerous sophisticated and versatile strategies to escape the attack of immune cells such as NK cells. Here, we investigate whether the KSHV derived cytokine (vIL-6) and chemokines (vMIP-I, vMIP-II, vMIP-III) affect NK cell activity. Using transwell migration assays, KSHV infected cells, as well as fusion and recombinant proteins, we show that out of the four cytokine/chemokines encoded by KSHV, vMIP-II is the only one that binds to the majority of NK cells, affecting their migration. We demonstrate that vMIP-II binds to two different receptors, CX3CR1 and CCR5, expressed by naïve CD56^Dim CD16^Pos NK cells and activated NK cells, respectively. Furthermore, we show that the binding of vMIP-II to CX3CR1 and CCR5 blocks the binding of the natural ligands of these receptors, Fractalkine (Fck) and RANTES, respectively. Finally, we show that vMIP-II inhibits the migration of naïve and activated NK cells towards Fck and RANTES. Thus, we present here a novel mechanism in which KSHV uses a unique protein that antagonizes the activity of two distinct chemokine receptors to inhibit the migration of naïve and activated NK cells.

NK cells belong to the innate immune system, able to rapidly kill tumors and various pathogens. They reside in the blood and in various tissues and traffic to different infected organs through the usage of different chemokines and chemokine receptors. KSHV is a master of immune evasion, and around a quarter of the KSHV encoded genes are dedicated to interfere with immune cell recognition. Here, we investigate the role played by the KSHV derived cytokine and chemokines (vIL-6, vMIP-I, vMIP-II, vMIP-III) in modulating NK cell activity. We show that vMIP-II binds and inhibits the activity of two different receptors, CX3CR1 and CCR5, expressed by naïve NK cells and by activated NK cells, respectively. Thus, we demonstrate here a novel mechanism in which KSHV uses a unique protein that antagonizes the activity of two distinct chemokine receptors to inhibit the migration of naïve and activated NK cells.

The effect of erythropoietin on autologous stem cell-mediated bone regeneration

Mesenchymal stem cells (MSCs) although used for bone tissue engineering are limited by the requirement of isolation and culture prior to transplantation. Our recent studies have shown that biomaterial implants can be engineered to facilitate the recruitment of MSCs. In this study, we explore the ability of these implants to direct the recruitment and the differentiation of MSCs in the setting of a bone defect. We initially determined that both stromal derived factor-1alpha (SDF-1α) and erythropoietin (Epo) prompted different degrees of MSC recruitment. Additionally, we found that Epo and bone morphogenetic protein-2 (BMP-2), but not SDF-1α, triggered the osteogenic differentiation of MSCs in vitro. We then investigated the possibility of directing autologous MSC-mediated bone regeneration using a murine calvaria model. Consistent with our in vitro observations, Epo-releasing scaffolds were found to be more potent in bridging the defect than BMP-2 loaded scaffolds, as determined by computed tomography (CT) scanning, fluorescent imaging and histological analyses. These results demonstrate the tremendous potential, directing the recruitment and differentiation of autologous MSCs has in the field of tissue regeneration.

Recruitment of Th1 effector cells in human tuberculosis: hierarchy of chemokine receptor(s) and their ligands

Selective recruitment of IFN-γ biased Th1 effector cells at the pathologic site(s) determines the local immunity of tuberculosis (TB). We observed the enrichment of CXCR3, CCR5 and CD11a(high) T cells in the peripheral blood, pleural fluid and bronchoalveolar lavage of TB pleural effusion (TB-PE) and miliary tuberculosis (MTB) patients respectively. CXCR3(+)CCR5(+) T cells were significantly high at the local disease site(s) in both the forms of TB and their frequency was highest among activated lymphocytes in TB-PE. Interestingly, all CCR5(+) cells were invariably positive for CXCR3 but all CXCR3(+) cells did not co-express CCR5 in pleural fluid whereas the situation was reverse in bronchoalveolar lavage. These CXCR3(+)CCR5(+) cells dominantly produced IFN-γ in response to Mycobacterium tuberculosis antigen. In vitro chemotaxis assay indicates dominant role of RANTES and IP-10 in the selective recruitment of CXCR3(+)CCR5(+)cells at the tubercular pathologic sites.

Human chemokines as antimicrobial peptides with direct parasiticidal effect on Leishmania mexicana in vitro

Chemokines and chemokine receptor-mediated effects are important mediators of the immunological response and cure in human leishmaniasis. However, in addition to their signalling properties for leukocytes, many chemokines have also been shown to act directly as antimicrobial peptides on bacteria and fungi. We screened ten human chemokines (CXCL2, CXCL6, CXCL8, CXCL9, CXCL10, CCL2, CCL3, CCL20, CCL27, CCL28) for antimicrobial effects on the promastigote form of the protozoan parasite Leishmania mexicana, and observed direct parasiticidal effects of several, CCL28 being the most potent. Damage to the plasma membrane integrity could be visualised by entrance of propidium iodide, as measured with flow cytometry, and by scanning electron microscopy, which showed morphological changes and aggregation of cells. The findings were in concordance with parasiticidal activity, measured by decreased mitochondrial activity in an MTT-assay. This is the first report of direct antimicrobial activity by chemokines on parasites. This component of immunity against Leishmania parasites identified here warrants further investigation that might lead to new insight in the mechanisms of human infection and/or new therapeutic approaches.

CCR1 blockade reduces tumor burden and osteolysis in vivo in a mouse model of myeloma bone disease

The chemokine CCL3/MIP-1α is a risk factor in the outcome of multiple myeloma (MM), particularly in the development of osteolytic bone disease. This chemokine, highly overexpressed by MM cells, can signal mainly through 2 receptors, CCR1 and CCR5, only 1 of which (CCR1) is responsive to CCL3 in human and mouse osteoclast precursors. CCR1 activation leads to the formation of osteolytic lesions and facilitates tumor growth. Here we show that formation of mature osteoclasts is blocked by the highly potent and selective CCR1 antagonist CCX721, an analog of the clinical compound CCX354. We also show that doses of CCX721 selected to completely inhibit CCR1 produce a profound decrease in tumor burden and osteolytic damage in the murine 5TGM1 model of MM bone disease. Similar effects were observed when the antagonist was used prophylactically or therapeutically, with comparable efficacy to that of zoledronic acid. 5TGM1 cells were shown to express minimal levels of CCR1 while secreting high levels of CCL3, suggesting that the therapeutic effects of CCX721 result from CCR1 inhibition on non-MM cells, most likely osteoclasts and osteoclast precursors. These results provide a strong rationale for further development of CCR1 antagonists for the treatment of MM and associated osteolytic bone disease.

Contractile activity of human skeletal muscle cells prevents insulin resistance by inhibiting pro-inflammatory signalling pathways

AIMS/HYPOTHESIS

Obesity is closely associated with muscle insulin resistance and is a major risk factor for the pathogenesis of type 2 diabetes. Regular physical activity not only prevents obesity, but also considerably improves insulin sensitivity and skeletal muscle metabolism. We sought to establish and characterise an in vitro model of human skeletal muscle contraction, with a view to directly studying the signalling pathways and mechanisms that are involved in the beneficial effects of muscle activity.

METHODS

Contracting human skeletal muscle cell cultures were established by applying electrical pulse stimulation. To induce insulin resistance, skeletal muscle cells were incubated with human adipocyte-derived conditioned medium, monocyte chemotactic protein (MCP)-1 and chemerin.

RESULTS

Similarly to in exercising skeletal muscle in vivo, electrical pulse stimulation induced contractile activity in human skeletal muscle cells, combined with the formation of sarcomeres, activation of AMP-activated protein kinase (AMPK) and increased IL-6 secretion. Insulin-stimulated glucose uptake was substantially elevated in contracting cells compared with control. The incubation of skeletal muscle cells with adipocyte-conditioned media, chemerin and MCP-1 significantly reduced the insulin-stimulated phosphorylation of Akt. This effect was abrogated by concomitant pulse stimulation of the cells. Additionally, pro-inflammatory signalling by adipocyte-derived factors was completely prevented by electrical pulse stimulation of the myotubes.

CONCLUSIONS/INTERPRETATION

We showed that the effects of electrical pulse stimulation on skeletal muscle cells were similar to the effect of exercise on skeletal muscle in vivo in terms of enhanced AMPK activation and IL-6 secretion. In our model, muscle contractile activity eliminates insulin resistance by blocking pro-inflammatory signalling pathways. This novel model therefore provides a unique tool for investigating the molecular mechanisms that mediate the beneficial effects of muscle contraction.

[Inhibitory effect of CMTM5 on xenografted human prostatic cancer in nude mice]

OBJECTIVE

To investigate the inhibitory effect of CKLF-like MARVEL transmembrane domain containing 5 (CMTM5) on xenografted human prostatic cancer in nude mice and its action mechanism.

METHODS

We established a model of xenografted prostatic cancer by inoculating PC-3 cells subcutaneously into nude mice, and 3 weeks later injected CMTM5 adenovirus locally into the tumor followed by daily observation of the tumor volume and body weight of the experimental animals. All the rats were killed 2 weeks after CMTM5 injection and the tumor tissue harvested for detection of the inhibitory effect of CMTM5 on the expressions of VEGF and NF-kappaB proteins by immunohistochemistry.

RESULTS

The tumor volume was significantly smaller and body weight of the CMTM5-treated mice were (573.39 +/- 175.24) mm3 and (0.55 +/- 0.11) g, respectively, significantly decreased as compared with those of the controls ([1482.50 +/- 327.86] mm3 and [1.31 +/- 0.29] g) (P = 0.03 and P = 0.027). Immunohistochemistry showed that the expressions of VEGF and NF-kappaB were obviously down-regulated in the CMTM5 group in comparison with the control group.

CONCLUSION

CMTM5 suppresses the growth of prostate cancer by down-regulating the expressions of VEGF and NF-kappaB.

Chemokines influence the migration and fate of neural precursor cells from the young adult and middle-aged rat subventricular zone

We have previously demonstrated a role for the chemokines MCP-1, MIP-1α and GRO-α in directing subventricular zone (SVZ)-derived neural precursor cell migration towards the site of cell death in the adult rodent brain. However the influence of chemokines such as MCP-1, MIP-1α and GRO-α on the differentiation of adult neural precursor cells has not previously been investigated. Further, as the majority of neurological disorders and injuries occur during ageing, it is important to investigate the effect of chemokines on adult neural precursor cell cultures obtained from the ageing brain. This study therefore examined the effect of MCP-1, MIP-1α and GRO-α on SVZ-derived neural precursor cell differentiation in vitro, and assessed whether precursor cells from the middle-aged rat brain (13 months old) follow the same migratory and differential profile as neural precursor cells obtained from the young adult rat brain (2 months old). We observed that each of the chemokines examined generated differing effects in regards to neuronal or glial differentiation. Further, both MIP-1α and GRO-α increased total cell number, suggesting an effect on precursor cell proliferation and/or survival. In agreement with cultures obtained from young adult brains, SVZ-derived neural precursor cells cultured from the middle-aged brain exhibited chemotactic migration in response to a concentration gradient. These results indicate that the chemokines MCP-1, MIP-1α and GRO-α can influence both the migration and fate choice of SVZ-derived neural precursor cells, as well as promoting cell viability. While a response to each of these chemokines is maintained in the middle-aged brain, a distinct age-related alteration in differential fate can be identified.

Mesenchymal stem cells exhibit firm adhesion, crawling, spreading and transmigration across aortic endothelial cells: effects of chemokines and shear

Mesenchymal stem cells (MSCs) have anti-inflammatory and immunosuppressive properties and may be useful in the therapy of diseases such as arteriosclerosis. MSCs have some ability to traffic into inflamed tissues, however to exploit this therapeutically their migratory mechanisms need to be elucidated. This study examines the interaction of murine MSCs (mMSCs) with, and their migration across, murine aortic endothelial cells (MAECs), and the effects of chemokines and shear stress. The interaction of mMSCs with MAECs was examined under physiological flow conditions. mMSCs showed lack of interaction with MAECs under continuous flow. However, when the flow was stopped (for 10min) and then started, mMSCs adhered and crawled on the endothelial surface, extending fine microvillous processes (filopodia). They then spread extending pseudopodia in multiple directions. CXCL9 significantly enhanced the percentage of mMSCs adhering, crawling and spreading and shear forces markedly stimulated crawling and spreading. CXCL9, CXCL16, CCL20 and CCL25 significantly enhanced transendothelial migration across MAECs. The transmigrated mMSCs had down-regulated receptors CXCR3, CXCR6, CCR6 and CCR9. This study furthers the knowledge of MSC transendothelial migration and the effects of chemokines and shear stress which is of relevance to inflammatory diseases such as arteriosclerosis.

Effects of vaspin, chemerin and omentin-1 on feeding behavior and hypothalamic peptide gene expression in the rat

Visceral adipose tissue-derived serpin (vaspin) improves glucose tolerance and insulin sensitivity in diet-induced obese mice. Chemerin may increase insulin sensitivity in adipose tissue and seems to be associated with several key aspects of metabolic syndrome. Decreased levels of omentin-1 are associated with increasing obesity and insulin resistance. Our study aimed to investigate the effects of vaspin, chemerin and omentin-1 acute administration on feeding and hypothalamic gene expression of peptides which play a key role in feeding regulation. 35 rats were injected into the arcuate nucleus (ARC) of the hypothalamus with either saline (n=8), vaspin (1μg/kg; n=9), chemerin (8μg/kg; n=9), or omentin-1 (8μg/kg; n=9). Food intake in the following 24h was recorded, thereafter rats were sacrificed. Total RNA was extracted from hypothalami and reverse transcribed to evaluate hypothalamic gene expression of agouti-related peptide (AgRP), neuropeptide Y (NPY), orexin-A, cocaine- and amphetamine-regulated transcript (CART), corticotrophin releasing hormone (CRH) and proopiomelanocortin (POMC), by real-time reverse transcription polymerase chain reaction. Compared to vehicle, vaspin injection significantly decreased feeding, while chemerin and omentin-1 had no effect in the tested dose. Vaspin treatment significantly decreased NPY and increased POMC gene expression. Chemerin treatment led to a significant increase of both AgRP and POMC gene expression. Omentin-1 treatment did not modify gene expression of the investigated peptides. Therefore, vaspin is an adipokine triggering anorectic pathways in the hypothalamus, where reduction of NPY and increase of POMC mRNA levels mediate feeding inhibition. Chemerin and omentin-1 have no effect on feeding in the tested dose.

Sciatic nerve injury induces functional pro-nociceptive chemokine receptors in bladder-associated primary afferent neurons in the rat

Visceral sensory afferents during disease or following injury often produce vague, diffuse body sensations, and pain referred to somatic targets. Alternatively, injury due to trauma or disease of somatic nerve targets can also lead to referred pain in visceral targets via a somatovisceral reflex. Both phenomenons are thought to be due to convergence of visceral and somatic afferents within the spinal cord. To investigate a potential peripheral influence for referred pain in visceral targets following somatic nerve injury, we examined whether a sciatic nerve injury known to produce hindpaw tactile hyperalgesia alters the frequency of micturition and the sensitivity of bladder-associated sensory neurons to pro-nociceptive chemokines. Adult female Sprague-Dawley rats received injections of cholera toxin B subunit conjugated to 555 into urinary bladder wall to retrogradely label visceral primary afferent neurons. After 7 days, the right sciatic nerve of these animals was subjected to a lysophosphatidylcholine (LPC)-induced focal demyelination injury. Pre- and post-injury tactile sensitivity in the hind paw and micturition frequency were assayed. Animals were allowed to survive for 14-28 days. Lumbosacral and lumbar dorsal root ganglia (DRG) ipsilateral to the nerve injury were acutely dissociated from sham and nerve injured animals. Bladder wall-associated sensory neurons identified via the retrograde marker were assayed for fluxes in intracellular calcium following administration of pro-nociceptive chemokines. The assayed chemokines included monocyte chemoattractant protein-1 (MCP1/CCL2) and stromal cell derived factor-1 alpha (SDF1/CXCL12). LPC nerve injured animals exhibited tactile hyperalgesia and increased micturition frequency for at least 28 days. Focal demyelination of the sciatic nerve also increased the number of injured L₄L₅ and non-injured L₆-S₂ bladder-associated sensory neurons that responded to MCP1 and SDF1 when compared with sensory neurons derived from uninjured naïve and sham-injured control animals. Taken together, these data suggest that some visceral hypersensitivity states may have a somatic origin. More importantly, nociceptive somatovisceral sensation may be mediated by upregulation of chemokine signaling in visceral sensory neurons.