Effects of CC, CXC, C, and CX3C chemokines on proliferation of myeloid progenitor cells, and insights into SDF-1-induced chemotaxis of progenitors

Follicular fluid exosomes inhibit BDNF expression and promote the secretion of chemokines in granulosa cells by delivering miR-10b-5p

Ovulation is an inflammatory response. Before ovulation, follicle cells release chemokines to recruit immune cells and promote ovulation. The objective of this study was to investigate whether follicular fluid exosomes promote chemokine secretion by granulosa cells (GCs). Porcine follicular fluid exosomes and follicular GCs were isolated in vitro. GCs were treated with follicular fluid exosomes in vitro and the differential gene expression profiles of the exosome-treated and control groups were obtained by transcriptome sequencing. The results showed that, when compared to the controls, the expression of the chemokines CCL2 and CXCL8 was significantly increased, whereas the expression of brain-derived neurotrophic factor (BDNF) was significantly decreased. The miRNA expression profiles in follicular fluid exosomes were obtained by microRNA sequencing. The results showed that exosomes carried many microRNAs, and that miR-10b-5p carried by exosomes could promote the secretion of CCL2 and CXCL8 by targeting BDNF. In conclusion, the present study demonstrates that exosomes promote the secretion of CCL2 and CXCL8 by granulosa cells through the miR-10b-5p/BDNF axis to promote ovulation.

Simulated microgravity affects stroma-dependent ex vivo myelopoiesis

Microgravity is known negatively affect physiology of living beings, including hematopoiesis. Dysregulation of hematopoietic cells and supporting stroma relationships in bone marrow niche may be in charge. We compared the efficacy of ex vivo expansion of hematopoietic stem and progenitor cells (HSPCs) in presence of native or osteocommitted MSCs under simulated microgravity (Smg) using Random Positioning Machine (RPM). In comparison with 1 g, a decrease of MSC-associated HSPCs and an increase of floating HSPCs was observed after 7 days of Smg exposure. Among floating HSPCs, primitive progenitors were presented by late CD34⁺/133^-. Total CFUs as well as erythroid (BFU-E) and granulocytic (CFU-G) numbers were lower. MSC-associated primitive HSPCs demonstrated increased proportion of late CD34⁺/133^- in expense of early CD34^-/133⁺. Osteo-MSCs preferentially supported late primitive CD34⁺ and more committed HSPCs as followed from increase of CFUs, and CD235a⁺ erythroid progenitors. Under Smg, an increased VEGF, eotaxin, and GRO-a levels, and a decrease in RANTES were found in the osteo-MSC-HSPC co-cultures. IL-6,-8, -13, G-CSF, GRO-a, MCP-3, MIP-1b, VEGF increased in co-culture with osteo-MSCs vs intact MSCs. Based on the findings, the misbalance between primitive/committed HSPCs and a decrease in hematopoiesis-supportive activity of osteocommitted cells are supposed to underline hematopoietic disorders during space flights.

Chemokine CCL18 Promotes Phagocytosis Through Its Receptor CCR8 Rather than PITPNM3 in Human Microglial Cells

CCL18 is a CC chemokine that exhibits diverse functions through interaction with various cell subsets with both proinflammatory anti-inflammatory properties through its receptors CCR8 (CC chemokine receptor 8) and PITPNM3 (phosphatidylinositol transfer protein 3). However, the function of CCL18 in microglia remains unclear. In this study, we show that CCL18 did not change the expression of the inflammatory factors, interleukin (IL)-1β, IL-6, tumor necrosis factor alpha (TNF-α), or inducible nitric oxide synthase (iNOS), but significantly induced expression of the macrophage markers, MRC-1 and ARG-1 M2, in a human microglial clone 3 cell line (HMC3). Phagocytosis by HMC3 cells was significantly enhanced in the presence of CCL18, indicated by uptake of amyloid-β and dextran. CCR8 and PITPNM3 were both expressed on HMC3 cells, but selective knockdown of CCR8 and PITPNM3 showed that only the former played a dominant role in phagocytosis of HMC3 through the nuclear factor kappa B (NF-κB)/Src signaling pathway. Our results suggest that CCL18 could have anti-inflammatory activity and activate the phagocytic function of microglia, which is involved in neural development, homeostasis, and repair mechanisms.

CXCL15/Lungkine has suppressive activity on proliferation and expansion of multi-potential, erythroid, granulocyte and macrophage progenitors in S-phase specific manner

Cytokines/chemokines regulate hematopoiesis, most having multiple cell actions. Numerous but not all chemokine family members act as negative regulators of hematopoietic progenitor cell (HPC) proliferation, but very little is known about such effects of the chemokine, CXCL15/Lungkine. We found that CXCL15/Lungkine-/- mice have greatly increased cycling of multi cytokine-stimulated bone marrow and spleen hematopoietic progenitor cells (HPCs: CFU-GM, BFU-E, and CFU-GEMM) and CXCL15 is expressed in many bone marrow progenitor and other cell types. This suggests that CXCL15/Lungkine acts as a negative regulator of the cell cycling of these HPCs in vivo. Recombinant murine CXCL15/Lungkine, decreased numbers of functional HPCs during cytokine-enhanced ex-vivo culture of lineage negative mouse bone marrow cells. Moreover, CXCL15/Lungkine, through S-Phase specific actions, was able to suppress in vitro colony formation of normal wildtype mouse bone marrow CFU-GM, CFU-G, CFU-M, BFU-E, and CFU-GEMM. This clearly identifies the negative regulatory activity of CXCL15/Lungkine on proliferation of multiple types of mouse HPCs.

A humanized monoclonal antibody against the endothelial chemokine CCL21 for the diagnosis and treatment of inflammatory bowel disease

Chemokines are small proteins that promote leukocyte migration during development, infection, and inflammation. We and others isolated the unique chemokine CCL21, a potent chemo-attractant for naïve T-cells, naïve B-cells, and immature dendritic cells. CCL21 has a 37 amino acid carboxy terminal extension that is distinct from the rest of the chemokine family, which is thought to anchor it to venule endothelium where the amino terminus can interact with its cognate receptor, CCR7. We and others have reported that venule endothelium expressing CCL21 plays a crucial role in attracting naïve immune cells to sites of antigen presentation. In this study we generated a series of monoclonal antibodies to the amino terminus of CCL21 in an attempt to generate an antibody that blocked the interaction of CCL21 with its receptor CCR7. We found one humanized clone that blocked naïve T-cell migration towards CCL21, while memory effector T-cells were less affected. Using this monoclonal antibody, we also demonstrated that CCL21 is expressed in the mucosal venule endothelium of the large majority of inflammatory bowel diseases (IBD), including Crohn's disease, ulcerative colitis, and also in celiac disease. This expression correlated with active IBD in 5 of 6 cases, whereas none of 6 normal bowel biopsies had CCL21 expression. This study raises the possibility that this monoclonal antibody could be used to diagnose initial or recurrent of IBD. Significantly, this antibody could also be used for therapeutic intervention in IBD by selectively interfering with recruitment of naïve immune effector cells to sites of antigen presentation, without harming overall memory immunity.

Recent Trends in Multipotent Human Mesenchymal Stem/Stromal Cells: Learning from History and Advancing Clinical Applications

Early cell biology reports demonstrated the presence of cells with stem-like properties in bone marrow, with both hematopoietic and mesenchymal lineages. Over the years, various investigations have purified and characterized mesenchymal stromal/stem cells (MSCs) from different human tissues as cells with multilineage differentiation potential under the appropriate conditions. Due to their appealing characteristics and versatile potentials, MSCs are leveraged in many applications in medicine such as oncology, bioprinting, and as recent as therapeutics discovery and innovation for COVID-19. To date, studies indicate that MSCs have varied differentiation capabilities into different cell types, and demonstrate immunomodulating and anti-inflammatory properties. Different microenvironments or niche for MSCs and their resulting heterogeneity may influence attendant cellular behavior and differentiation capacity. The potential clinical applications of MSCs and exosomes derived from these cells have led to an avalanche of research reports on their properties and hundreds of clinical trials being undertaken. There is ample reason to think, as discussed in this expert review that the future looks bright and promising for MSC research, with many clinical trials under way to ascertain their clinical utility. This review provides a synthesis of the latest advances and trends in MSC research to allow for broad and critically informed use of MSCs. Early observations of the presence of these cells in the bone marrow and their remarkable differentiation capabilities and immunomodulation are also presented.

The immunosuppressive and pro-tumor functions of CCL18 at the tumor microenvironment

Chemokines are essential mediators of immune cell trafficking. In a tumor microenvironment context, chemotactic cytokines are known to regulate the migration, positioning and interaction of different cell subsets with both anti- and pro-tumor functions. Additionally, chemokines have critical roles regarding non-immune cells, highlighting their importance in tumor growth and progression. CCL18 is a primate-specific chemokine produced by macrophages and dendritic cells. This chemokine presents both constitutive and inducible expression. It is mainly associated with a tolerogenic response and involved in maintaining homeostasis of the immune system under physiological conditions. Recently, CCL18 has been noticed as an important component of the complex chemokine system involved in the biology of tumors. This chemokine induces T regulatory cell differentiation and recruitment to the tumor milieu, with subsequent induction of a pro-tumor (M2-like) macrophage phenotype. CCL18 is also directly involved in cancer cell-invasion, migration, epithelial-to-mesenchymal transition and angiogenesis stimulation, pinpointing an important role in the promotion of cancer progression. Interestingly, this chemokine is highly expressed in tumor tissues, particularly at the invasive front of more advanced stages (e.g. colorectal cancer), and high levels are detected in the serum of patients, correlating with poor prognosis. Despite the promising role of CCL18 as a biomarker and/or therapeutic target to hamper disease progression, its pleiotropic functions in a context of cancer are still poorly explored. The scarce knowledge concerning the receptors for this chemokine, together with the insufficient insight on the downstream signaling pathways, have impaired the selection of this molecule as an immediate target for translational research. In this Review, we will discuss recent findings concerning the role of CCL18 in cancer, integrate recently disclosed molecular mechanisms and compile data from current clinical studies.

HbF Levels in Sickle Cell Disease Are Associated with Proportion of Circulating Hematopoietic Stem and Progenitor Cells and CC-Chemokines

The concentration of circulating hematopoietic stem and progenitor cells has not been studied longitudinally. Here, we report that the proportions of Lin-CD34+38- hematopoietic multipotent cells (HMCs) and of Lin-CD34+CD38+ hematopoietic progenitors cells (HPCs) are highly variable between individuals but stable over long periods of time, in both healthy individuals and sickle cell disease (SCD) patients. This suggests that these proportions are regulated by genetic polymorphisms or by epigenetic mechanisms. We also report that in SCD patients treated with hydroxyurea, the proportions of circulating HMCs and HPCs show a strong positive and negative correlation with fetal hemoglobin (HbF) levels, respectively. Titration of 65 cytokines revealed that the plasma concentration of chemokines CCL2, CCL11, CCL17, CCL24, CCL27, and PDGF-BB were highly correlated with the proportion of HMCs and HPCs and that a subset of these cytokines were also correlated with HbF levels. A linear model based on four of these chemokines could explain 80% of the variability in the proportion of circulating HMCs between individuals. The proportion of circulating HMCs and HPCs and the concentration of these chemokines might therefore become useful biomarkers for HbF response to HU in SCD patients. Such markers might become increasingly clinically relevant, as alternative treatment modalities for SCD are becoming available.

Platelets Boost Recruitment of CD133+ Bone Marrow Stem Cells to Endothelium and the Rodent Liver-The Role of P-Selectin/PSGL-1 Interactions

We previously demonstrated that clinical administration of mobilized CD133⁺ bone marrow stem cells (BMSC) accelerates hepatic regeneration. Here, we investigated the potential of platelets to modulate CD133⁺BMSC homing to hepatic endothelial cells and sequestration to warm ischemic livers. Modulatory effects of platelets on the adhesion of CD133⁺BMSC to human and mouse liver-sinusoidal- and micro- endothelial cells (EC) respectively were evaluated in in vitro co-culture systems. CD133⁺BMSC adhesion to all types of EC were increased in the presence of platelets under shear stress. This platelet effect was mostly diminished by antagonization of P-selectin and its ligand P-Selectin-Glyco-Ligand-1 (PSGL-1). Inhibition of PECAM-1 as well as SDF-1 receptor CXCR4 had no such effect. In a model of the isolated reperfused rat liver subsequent to warm ischemia, the co-infusion of platelets augmented CD133⁺BMSC homing to the injured liver with heightened transmigration towards the extra sinusoidal space when compared to perfusion conditions without platelets. Extravascular co-localization of CD133⁺BMSC with hepatocytes was confirmed by confocal microscopy. We demonstrated an enhancing effect of platelets on CD133⁺BMSC homing to and transmigrating along hepatic EC putatively depending on PSGL-1 and P-selectin. Our insights suggest a new mechanism of platelets to augment stem cell dependent hepatic repair.

IL-17D: A Less Studied Cytokine of IL-17 Family

The interleukin-17 (IL-17) family is a relatively new family of cytokines consisting of 6 related factors (IL-17A-IL-17F), while the receptor family consists of 5 members: IL-17RA-IL-17RE. IL-17A is the prototype member of this family, which is also the signature cytokine of T helper 17 (Th17) cells. Th17 cells are involved in the development of autoimmune disease, inflammation, and tumors. Although IL-17D is similar to IL-17A in its ability to induce inflammatory cytokine production, there are fewer studies on IL-17D. Recently, the role of IL-17D in tumors and infections has attracted our attention. Some knowledge of function of IL-17D has been gained by studies using nonmammalian species. In this review, we introduce the structural characteristics, expression patterns, and biological characteristics of IL-17D along with its potential function in the pathogenesis of disease.

Discovery of CCL18 antagonist blocking breast cancer metastasis

Our previous studies have proved that CCL18 is the most secreted chemokine in breast cancer microenvironment by tumor associated macrophages (TAMs). CCL18 promotes breast cancer invasiveness by binding to its cognate receptor PITPNM3 and activating the downstream signaling pathways. The high level of CCL18 in serum or tumor stroma is associated with tumor metastasis and poor patients overall survival. In this study, we identify an effective small molecular compound (SMC) to antagonize the effect of CCL18. We screen more than 1000 SMCs from Sun Yat-sen University SMC library and select 15 top scored SMCs by using computer-aided virtual screening based on the structure of CCL18. Then in vitro cell migration assay narrows down the selected 15 SMCs to the most effective SMC-21598. We find 10 µM SMC-21598 significantly inhibits CCL18-induced breast cancer cells adherence, invasiveness, and migration. Our further surface plasmon resonance (SPR), fluorescence spectroscopy and isothermal titration calorimetry (ITC) assays reveal that SMC-21598 binds tightly to CCL18, which blocks the binding of CCL18 with its receptor PITPNM3. The in vivo animal experiments show that SMC-21598 doesn't significantly affect xenografts growth, but inhibits lung metastasis. Our study provides a potential lead compound to antagonize CCL18 function. It would be of great significance to develop SMC drugs to ameliorate breast cancer metastasis and prolong patients' survival.

Membrane-anchored CCL20 augments HIV Env-specific mucosal immune responses

Background

Induction of broad immune responses at mucosal site remains a primary goal for most vaccines against mucosal pathogens. Abundance of evidence indicates that the co-delivery of mucosal adjuvants, including cytokines, is necessary to induce effective mucosal immunity. In the present study, we set out to evaluate the role of a chemokine, CCL20, as an effective mucosal adjuvant for HIV vaccine.

Methods

To evaluate the role of CCL20 as a potent adjuvant for HIV vaccine, we examined its effects on antigen-specific antibody responses, level of antibody-secreting cells, cytokine production and intestinal homing of plasma cells in vaccine immunized mice.

Results

CCL20-incorporated VLP administered by mucosal route (intranasal (n = 10, p = 0.0085) or intravaginal (n = 10, p = 0.0091)) showed much higher potency in inducing Env-specific IgA antibody response than those administered by intramuscular route (n = 10). For intranasal administration, the HIV Env-specific IFN-γ(751 pg/ml), IL-4 (566 pg/ml), IL-5 (811 pg/ml) production and IgA-secreting plasma cells (62 IgA-secreting plasma cells/10⁶ cells) in mucosal lamina propria were significantly augmented in CCL20-incorporated VLP immunized mice as compared to those immunized with Env only VLPs (p = 0.0332, 0.0398, 0.033, 0.0302 for IFN-γ, IL-4, IL-5, and IgA-secreting plasma cells, respectively).

Further, anti-CCL20 mAb partially suppressed homing of Env-specific IgA ASCs into small intestine in mice immunized with CCL20-incorporated VLP by intranasal (62 decreased to 16 IgA- secreting plasma cells/10⁶ cells, p = 0.0341) or intravaginal (52 decreased to 13 IgA- secreting plasma cells/10⁶ cells, p = 0.0332) routes.

Conclusion

Our data indicated that the VLP-incorporated CCL20 can enhance HIV Env-specific immune responses in mice, especially those occurring in the mucosal sites. We also found that i.m. prime followed by mucosal boost is critical and required for CCL20 to exert its full function as an effective mucosal adjuvant. Therefore, co-incorporation of CCL20 into Env VLPs when combined with mucosal administration could represent a novel and promising HIV vaccine candidate.

Effects of Mesenchymal Stem Cell Derivatives on Hematopoiesis and Hematopoietic Stem Cells

Hematopoiesis is a balance among quiescence, self-renewal, proliferation, and differentiation, which is believed to be firmly adjusted through interactions between hematopoietic stem and progenitor cells (HSPCs) with the microenvironment. This microenvironment is derived from a common progenitor of mesenchymal origin and its signals should be capable of regulating the cellular memory of transcriptional situation and lead to an exchange of stem cell genes expression. Mesenchymal stem cells (MSCs) have self-renewal and differentiation capacity into tissues of mesodermal origin, and these cells can support hematopoiesis through release various molecules that play a crucial role in migration, homing, self-renewal, proliferation, and differentiation of HSPCs. Studies on the effects of MSCs on HSPC differentiation can develop modern solutions in the treatment of patients with hematologic disorders for more effective Bone Marrow (BM) transplantation in the near future. However, considerable challenges remain on realization of how paracrine mechanisms of MSCs act on the target tissues, and how to design a therapeutic regimen with various paracrine factors in order to achieve optimal results for tissue conservation and regeneration. The aim of this review is to characterize and consider the related aspects of the ability of MSCs secretome in protection of hematopoiesis.

Modulation of Hematopoietic Chemokine Effects In Vitro and In Vivo by DPP-4/CD26

Dipeptidyl peptidase 4 (DPP4)/CD26 truncates certain proteins, and this posttranslational modification can influence their activity. Truncated (T) colony-stimulating factors (CSFs) are decreased in potency for stimulating proliferation of hematopoietic progenitor cells (HPCs). T-CXCL12, a modified chemokine, is inactive as an HPC chemotactic, survival, and enhancing factor for replating or ex-vivo expansion of HPCs. Moreover, T-CSFs and T-CXCL12 specifically downmodulates the positively acting effects of their own full-length molecule. Other chemokines have DPP4 truncation sites. In the present study, we evaluated effects of DPP4 inhibition (by Diprotin A) or gene deletion of HPC on chemokine inhibition of multicytokine-stimulated HPC, and on chemokine-enhancing effects on single CSF-stimulated HPC proliferation, as well as effects of DPP4 treatment of a number of chemokines. Myelosuppressive effects of chemokines with, but not without, a DPP4 truncation site were greatly enhanced in inhibitory potency by pretreating target bone marrow (BM) cells with Diprotin A, or by assaying their activity on dpp4/cd26(-/-) BM cells. DPP4 treatment of myelosuppressive chemokines containing a DPP4 truncation site produced a nonmyelosuppressive molecule, but one which had the capacity to block suppression by that unmodified chemokine both in vitro and in vivo. Additionally, DPP4 treatment ablated the single cytokine-stimulated HPC-enhancing activity of CCL3/MIP-1α and CCL4/MIP-1β, and blocked the enhancing activity of each unmodified molecule, in vitro and in vivo. These results highlight the functional posttranslational modulating effects of DPP4 on chemokine activities, and information offering additional biological insight into chemokine regulation of hematopoiesis.

Multiplex Analysis of Serum Cytokines in Humans with Hantavirus Pulmonary Syndrome

Hantavirus pulmonary syndrome (HPS) is an acute zoonotic disease transmitted primarily through inhalation of virus-contaminated aerosols. Hantavirus infection of endothelial cells leads to increased vascular permeability without a visible cytopathic effect. For this reason, it has been suggested that the pathogenesis of HPS is indirect with immune responses, such as cytokine production, playing a dominant role. In order to investigate their potential contribution to HPS pathogenesis, we analyzed the serum of hantavirus-infected subjects and healthy controls for 68 different cytokines, chemokines, angiogenic, and growth factors. Our analysis identified differential expression of cytokines that promote tissue migration of mononuclear cells including T lymphocytes, natural killer cells, and dendritic cells. Additionally, we observed a significant upregulation of cytokines known to regulate leukocyte migration and subsequent repair of lung tissue, as well as cytokines known to increase endothelial monolayer permeability and facilitate leukocyte transendothelial migration. Conversely, we observed a downregulation of cytokines associated with platelet numbers and function, consistent with the thrombocytopenia observed in subjects with HPS. This study corroborates clinical findings and extends our current knowledge regarding immunological and laboratory findings in subjects with HPS.

In situ hematopoiesis: a regulator of TH2 cytokine-mediated immunity and inflammation at mucosal surfaces

Hematopoiesis refers to the development of blood cells in the body through the differentiation of pluripotent stem cells. Although hematopoiesis is a multifocal process during embryonic development, under homeostatic conditions it occurs exclusively within the bone marrow. There, a limited number of hematopoietic stem cells differentiate into a rapidly proliferating population of lineage-restricted progenitors that serve to replenish circulating blood cells. However, emerging reports now suggest that under inflammatory conditions, alterations in hematopoiesis that occur outside of the bone marrow appear to constitute a conserved mechanism of innate immunity. Moreover, recent reports have identified previously unappreciated pathways that regulate the egress of hematopoietic progenitor cells from the bone marrow, alter their activation status, and skew their developmental potential. These studies suggest that progenitor cells contribute to inflammatory response by undergoing in situ hematopoiesis (ISH). In this review, we highlight the differences between homeostatic hematopoiesis, which occurs in the bone marrow, and ISH, which occurs at mucosal surfaces. Further, we highlight factors produced at local sites of inflammation that regulate hematopoietic progenitor cell responses and the development of TH2 cytokine-mediated inflammation. Finally, we discuss the therapeutic potential of targeting ISH in preventing the development of inflammation at mucosal sites.

Mesenchymal stem cells markedly suppress inflammatory bone destruction in rats with adjuvant-induced arthritis

Mesenchymal stem cells (MSCs) have potential to differentiate into multiple cell lineages. Recently, it was shown that MSCs also have anti-inflammatory and immunomodulatory functions. In this report, we investigated the regulatory function of MSCs in the development of inflammatory bone destruction in rats with adjuvant-induced arthritis (AA rats). MSCs were isolated from rat bone marrow tissues, expanded in the presence of basic FGF, and intraperitoneally injected into AA rats. MSC administration significantly suppressed inflammatory parameters: swelling score, swelling width, and thickness of hind paw. Radiographic evaluation indicated that MSC significantly suppressed bone destruction. Histological analysis showed that administration of MSCs markedly suppressed osteoclastogenesis in AA rats. To further delineate their effects on osteoclastogenesis, MSCs were added to in vitro bone marrow cultures undergoing osteoclastogenesis. MSCs significantly suppressed osteoclastogenesis in this system. Chemokine receptor expression in MSCs was assessed by RT-PCR, and a chemotactic assay was performed using a transwell culture system. MSCs showed significant chemotaxis to MIP-1α (CCL3) and SDF-1α (CXCL12), chemokines preferentially expressed in the area of inflammatory bone destruction. Furthermore, MSCs expressed IL-10 and osteoprotegerin, cytokines that suppress osteoclastogenesis. These data suggest that recruitment of MSC to the area of bone destruction in AA rats could suppress inflammatory bone destruction and raise the possibility that MSCs may have potential for the treatment of inflammatory bone destruction in arthritis.

Pathomechanisms: homeostatic chemokines in health, tissue regeneration, and progressive diseases

Homeostatic chemokines control stem and progenitor cell migration and activation during vasculogenesis and organ development. They orchestrate hematopoietic stem cell (HSC) homing to their bone marrow niches and direct immature lymphocytes to a series of maturation sites within lymphoid organs. Along these lines, homeostatic chemokines regulate the niches of peripheral committed progenitor cell populations for tissue renewal. These biological functions support neovascularization and wound healing, including the recruitment of endothelial and other progenitor cells from the bone marrow. Here, we summarize the roles of homeostatic chemokines, their signaling receptors, and atypical decoy receptors during homeostasis and tissue regeneration in order to better understand their pathogenic roles in disease, for example, in diabetes complications, cancer, autoimmunity, epithelial hyperplasia, or hypertrophic scarring and fibrosis.

HGF and SDF-1-mediated mobilization of CD133+ BMSC for hepatic regeneration following extensive liver resection

BACKGROUND

The molecular mechanisms of haematopoietic stem cells (HSC) mobilization and homing to the liver after partial hepatectomy (PH) remain largely unexplored.

METHODS

Functional liver volume loss and regain was determined by computerized tomography (CT) volumetry in 30 patients following PH. Peripheral HSC mobilization was investigated by fluorescence-activated cell sorting (FACS) analyses and cytokine enzyme-linked immunosorbent assay assays. Migration of purified HSC towards hepatic growth factor (HGF) and stroma-derived factor-1 (SDF-1) gradients was tested in vitro. Mice after 70% PH were examined for HSC mobilization by FACS and cytokine mRNA expression in the liver. FACS-sorted HSC were administered after PH and hepatocyte proliferation was evaluated by immunohistochemical staining for Ki67.

RESULTS

Impaired liver function was noted after extended hepatic resection when compared to smaller resections. Patients with large liver resections were characterized by significantly higher levels of peripheral HSC which were positively correlated with the extent of resected liver volume and its regain after 3 weeks. Increased plasma levels of HGF, SDF-1 and insulin like growth factor (IGF-1) were evident within the first 6 hours post resection. Migration assays of human HSC in vitro showed a specific target-demonstrated migration towards recombinant HGF and SDF-1 gradients in a concentration and specific receptor (c-Met and CXCR4) dependent manner. The evaluation of peripheral human alpha foetoprotein expression demonstrated pronounced stemness following increased CD133(+) HSC in the course of liver regeneration following PH. Our human data were further validated in a murine model of PH and furthermore demonstrated increased hepatocyte proliferation subsequent to CD133(+) HSC treatment.

CONCLUSION

HGF and SDF-1 are required for effective HSC mobilization and homing to the liver after hepatic resection. These findings have significant implications for potential therapeutic strategies targeting chemotactant modulation and stem cell mobilization for liver protection and regeneration.

Opposite effects of two trichothecene mycotoxins, deoxynivalenol and nivalenol, on the levels of macrophage inflammatory protein (MIP)-1α and MIP-1β in HL60 cells

To elucidate the mechanisms underlying the toxicities of the trichothecene mycotoxins deoxynivalenol and nivalenol, their effects on the secretion of anti-hematopoietic chemokines, macrophage inflammatory protein-1α (MIP-1α) and MIP-1β in human promyelocytic leukemia cell line HL60 were investigated. Exposure to deoxynivalenol for 24h significantly induced the secretion of chemokines. The induction of these chemokines may account for the leukopenia after exposure to trichothecene mycotoxins. Treatment with nivalenol decreased the secretion of these chemokines. Our finding that deoxynivalenol induces the secretion of these chemokines, whereas nivalenol has the opposite effect, clearly indicates that the toxicity mechanisms of deoxynivalenol and nivalenol differ.

Activated expression of the chemokine Mig after chemotherapy contributes to chemotherapy-induced bone marrow suppression and lethal toxicity

Alterations in gene expression after chemotherapy may potentially help to identify mediators that induce suppression or regeneration in bone marrow. This paper reports our observation that the expression of the chemokine monokine induced by IFN-γ (Mig) and its receptor CXCR3 was significantly activated in mice after treatment with the chemotherapeutic agent 5-fluorouracil (5-FU). The neutralization of antibodies against the activated Mig increased the survival rate and accelerated BM recovery after chemotherapy. In addition, elevation of Mig plasma levels after 5-FU treatment corresponded with increased mortality. The cell cycle-inhibiting effect of the prophylactic administration of Mig protected hematopoietic progenitor cells (HPCs) from 1-β-d-arabinofuranosylcytosine in spleen colony assays and enhanced the irradiated recipients' survival. In CXCR3(-/-) mice, Mig did not propagate BM suppression, indicating that the suppressive effect of Mig is dependent on CXCR3. On the one hand, Mig stimulated p70 S6K and Erk1/2 pathways in mesenchymal stroma cells, inhibiting mesenchymal stroma cell-dependent HPC expansion. Moreover, Mig suppressed the STAT5 pathway in HPCs, inhibiting leukocyte differentiation. Our results strongly suggest that Mig contributes to the acute lethal toxicity arising from 5-FU administration. Neutralization of Mig may offer new strategies to alleviate BM toxicity with potentially dramatic implications for chemotherapy.

Tumor microenvironment modifications induced by soluble VEGF receptor expression in a rat liver metastasis model

Vascular endothelial growth factor is a potent pro-angiogenic growth factor which is also known to alter tumor microenvironment by inhibiting dendritic cell differentiation and promoting accumulation of myeloid-derived suppressor cells. In the present study, we analyzed the modifications induced by intratumoral expression of sFLT-1, a soluble VEGF receptor, in a rat metastatic colon carcinoma model. We generated colon cancer cell lines stably expressing sFLT-1 or a mock construct. Human umbilical vein endothelial cells cultured with conditioned medium from sFLT-1-expressing tumor cells exhibit a significantly decreased survival, demonstrating the functionality of the secreted sFLT-1. Invivo, sFLT-1 expression induced a 30% decrease in microvessel density in 15-day old experimental liver metastasis from colon carcinoma. Tumor growth was inhibited by 63% and 52% in left and right liver lobes respectively within 25days. In these tumors, sFLT-1 expression was associated with a decreased myeloid cell infiltration and a modification in the expression of several cytokines/chemokines. Altogether, these results suggest that VEGF trapping by sFLT-1 intratumoral expression results in reduced vascularization, tumor growth inhibition and modification of immune tumor microenvironment.

Hemopoietic progenitors: the role of eosinophil/basophil progenitors in allergic airway inflammation

Progenitor cells play important roles in the physiology and homeostasis of the overall hemopoietic system. The majority of hemopoietic activity takes place in the bone marrow, under the influence of resident marrow stromal cells, accessory cells, and/or their products. This constitutes the complex network of the hemopoietic inductive microenvironment, which is crucial for providing signals necessary for the maintenance of populations of progenitors at varying stages of lineage commitment. Accumulation of eosinophils and basophils in tissues is characteristic of allergic inflammation. A large body of evidence now exists which confirms that these tissue inflammatory events are coincident with relevant changes in progenitors; it has thus been hypothesized that the observed changes in mature cell numbers occur directly or indirectly as a result of differentiation of lineage-committed eosinophil/basophil, and perhaps other, progenitor cells. Differentiation and maturation of hemopoietic cells have traditionally been thought to be restricted to the bone marrow microenvironment. More recently, evidence has accumulated to suggest that some hemopoietic cells present in allergic tissue may be recruited from the bone marrow, traffic through the peripheral circulation and into tissues to participate in the ongoing inflammatory process at these distal sites. The clinical administration of monotherapy with topical corticosteroids, oral cysteinyl leukotriene antagonists and cytokine antagonists such as antibodies to interleukin-5, suggest that suppression of hemopoietic contributions to allergic inflammation may be necessary for full control of allergic inflammation and disease manifestations. In addition to progenitors being targets of therapy, they may well determine how and whether allergic inflammation is generated in early life, thus serving as biomarkers of disease.

Pretreatment with lornoxicam, a cyclooxygenase inhibitor, relieves postoperative immuno-suppression after total abdominal hysterectomy

Total abdominal hysterectomy (TAH) is most commonly performed for benign lesions and malignant diseases of the uterus. Postoperative immuno-suppression caused by TAH has become a serious clinical problem, due to the high incidence of infectious complications after this operation. Lornoxicam (LOR) is a member of non-steroidal anti-inflammatory drugs and a cyclooxygenase inhibitor. In this study, 45 patients undergoing TAH for uterine myoma were enrolled and given intravenous injection of normal saline (untreated patients) or LOR (8 or 16 mg) preoperatively (15 patients/group). We studied the effects of LOR on postoperative immuno-suppression by determining the serum levels of three cytokines, RANTES, monocyte chemotactic protein-1 (MCP-1), and stromal cell-derived factor 1alpha (SDF-1alpha). MCP-1 and RANTES are involved in the pathophysiology of acute and chronic inflammatory processes, and SDF-1alpha is considered as an inflammatory chemoattractant. Following TAH, the serum levels of RANTES were reduced in the untreated patients, but were significantly higher in the patients treated with LOR. In addition, the levels of MCP-1 and SDF-1alpha were significantly elevated in the untreated patients, but were significantly lower in the patients treated with LOR. Furthermore, preoperative treatment with LOR 16 mg could regulate the serum levels of these three chemokines more effectively, compared to that with LOR 8 mg. In conclusion, preoperatively intravenous injection of LOR may effectively restrain the decreased serum levels of RANTES and the increased expression of MCP-1 and SDF-1alpha in TAH patients. LOR may help to maintain the stability of immune function of TAH patients.

CXCR4 induction in hematopoietic progenitor cells from Fanca(-/-), -c(-/-), and -d2(-/-) mice

OBJECTIVE

Bone marrow failure is a near-universal occurrence in patients with Fanconi anemia (FA) and is thought to result from exhaustion of the hematopoietic stem cell (HSC) pool. Retrovirus-mediated expression of the deficient protein corrects this phenotype and makes FA a candidate disease for HSC-directed gene therapy. However, inherent repopulation deficits and stem cell attrition during conventional transduction culture prevent therapeutic chimerism.

MATERIALS AND METHODS

We previously reported rapid transduction protocols to limit stem cell losses after ex vivo culture. Here we describe a complementary strategy intended to improve repopulation through upregulation of chemokine receptor (CXCR) 4, a principal factor in hematopoietic homing.

RESULTS

Using murine models with transgenic disruption of Fanca, -c, and -d2, we found that c-kit(+) and sca-1(+) progenitor cells express levels of CXCR4 comparable with those of wild-type littermates. Lineage-depleted progenitor populations rapidly upregulated CXCR4 transcript and protein in response to cytokine stimulation or hypoxia, regardless of genotype. Hypoxia conditioning of lineage-depleted Fancc(-/-) progenitors also reduced oxidative stress, improved in vitro migration and led to improved chimerism in myeloablated recipients after transplantation.

CONCLUSION

These studies provide evidence that CXCR4 regulation in progenitor cells from transgenic mice representing multiple FA genotypes is intact and that modulation of homing offers a potential strategy to offset the FA HSC repopulation deficiency.

MCP-1, RANTES, and SDF-1 polymorphisms in Mexican patients with systemic lupus erythematosus

Chemokines and cytokines play an important role in the inflammatory development and progression of autoimmune diseases. The aim of the present study was to evaluate the role of MCP-1, SDF-1, and RANTES polymorphisms as susceptibility markers for systemic lupus erythematosus (SLE) in a group of Mexican patients. MCP-1-2518, SDF-1 G801A, and RANTES-28 polymorphisms were determined in 242 patients with SLE and 220 ethnically matched healthy controls by the polymerase chain reaction-restriction fragment length polymorphism technique. The differences between patients and healthy controls were evaluated by chi(2), Fisher's exact test, and Woolf method for odds ratio. A moderately increased frequency of MCP-1-2518 A allele (p = 0.033, pC = NS) and AA genotype (p = 0.017, pC = NS) existed in SLE patients compared with healthy controls. There was a relationship between polymorphisms and some clinical and laboratory characteristics. SLE patients with and without antiphospholipid syndrome demonstrated different distribution of SDF-1 G801A genotype frequencies. On the other hand, patients with leukopenia, anti-dsDNA, and antiphospholipid autoantibodies demonstrated different MCP-1-2518 genotype distribution compared with patients without these features. Our results suggest that MCP-1 polymorphism is moderately associated with the genetic susceptibility to SLE in Mexican individuals. The polymorphisms could be related to specific clinical and laboratory characteristics in these patients.

Expression pattern and cellular sources of chemokines in primary central nervous system lymphoma

The expression pattern of a subset of chemokines and their corresponding receptors was investigated in primary central nervous system lymphomas (PCNSL). The tumor cells consistently expressed CXCR4, CXCL12, CXCR5, and CXCL13, both at mRNA and protein levels. Cerebral endothelial cells were positive for CXCL12 and CXCL13, while reactive astrocytes and microglial cells expressed CXCL12, CCR5, and CCR6. Inflammatory T cells in PCNSL were characterized by CCR5 and CCR6 positivity. Taken together, our data indicate a cell type-specific repertoire of chemokine and chemokine receptor expression in PCNSL suggesting that chemokine-mediated interactions facilitate crossing of the blood-brain barrier as well as intracerebral dissemination of PCNSL cells. In addition, chemokines expressed by tumor cells may contribute to induction of reactive glial changes and influence the composition of inflammatory infiltrates in PCNSL. Therefore, cell type specific expression of distinct chemokine profiles likely plays a role in the pathogenesis of PCNSL and may contribute to their characteristic histological appearance.

Re-evaluation of the chicken MIP family of chemokines and their receptors suggests that CCL5 is the prototypic MIP family chemokine, and that different species have developed different repertoires of both the CC chemokines and their receptors

Analysis of the chicken genome has shown that the chicken has a different repertoire of chemokines and chemokine receptors to those of mammals and other species. In this study, we report the sequencing and analysis of a bacterial artificial chromosome containing the entire chicken MIP family CC chemokine cluster. The gene duplication and divergence events that have taken place in mammals do not appear to have occurred as extensively in the avian lineage, as chickens possess fewer MIP family chemokine genes than humans or mice. We previously proposed that the four chicken MIP family members be named chicken (ch) CCLi1-4, according to their position on chicken chromosome 19, until such time as further analysis could determine if any of them were direct orthologues of mammalian MIP family members. Our analysis herein, combined with that of others, suggests that chCCLi4 is the orthologue of mammalian CCL5, and that chCCLi3 (K203) may be an orthologue of human CCL16. The other two chemokines do not have obvious orthologues, and thus we propose that they should still be called chCCLi1 and chCCLi2, until their biological function is further characterised. A similar pattern applies to the MIP family chemokine receptors, with only three receptor genes present at the relevant locus in the chicken genome, compared to four in man and mouse (CCR1, CCR2, CCR3 and CCR5). Of the three chicken receptor genes, only two look likely to be receptors for the MIP family chemokines, the third grouping with human, mouse and chicken CCR8 in phylogenetic analysis. The two chicken MIP CC receptors (CCRs) are not direct orthologues of the mammalian MIP CCRs.

Synergistic inhibition in vivo of bone marrow myeloid progenitors by myelosuppressive chemokines and chemokine-accelerated recovery of progenitors after treatment of mice with Ara-C

OBJECTIVE

Selected chemokines suppress proliferation of hematopoietic progenitor cells (HPCs) in vitro; some of these have demonstrated inhibition of myelopoiesis in vivo. Because myelosuppressive chemokines synergize in vitro with other myelosuppressive chemokines, we sought to determine whether additional chemokines active in vitro were myelosuppressive in vivo and whether combinations of myelosuppressive chemokines synergized in vivo to dampen myelopoiesis. We also evaluated three chemokines in vivo for myeloprotection against Ara-C-induced decreases in HPCs.

METHODS

C3H/HeJ mice were used for analysis of in vivo influence of chemokines, with the end points being effects on absolute numbers and cycling status of HPCs.

RESULTS

When used alone, CCL2, CCL3, CCL19, CCL20, CXCL4, CXCL5, CXCL8, CXCL9, and XCL1 caused dose-dependent significant decreases in absolute numbers and cycling status of HPCs in vivo. The following combinations of two chemokines resulted in in vivo myelosuppression at concentrations much lower than that induced by each chemokine alone: CCL3 plus either CXCL8 or CXCL4, CXCL8 plus CXCL4, CCL2 plus either CCL20 or CXCL9, CCL20 plus CXCL9, CXCL5 plus either XCL1 or CCL19, XCL1 plus CCL19, and CCL3 plus CCL19. Also, mice injected with CXCL8, CXCL4, or the chimeric CXCL8/CXCL4 protein CXCL8M1 manifested accelerated recovery of absolute numbers of HPCs in response to the toxic effects of Ara-C administration.

CONCLUSIONS

A number of chemokines shown previously to manifest inhibitory effects in vitro for proliferation of HPCs are now demonstrated to also induce myelosuppression in vivo. Moreover, combinations of low dosages of two myelosuppressive chemokines when administered together demonstrate synergistic suppression in vivo. Additionally, chemokines, including a CXCL8M1 chimeric protein previously shown to manifest enhanced suppression of HPC proliferation in vitro and in vivo, accelerate HPC recovery after treatment of mice with Ara-C. These results may be of use for future clinical utility of chemokines in a myelosuppressive/myeloprotective setting.

Cytokines produced by cultured human umbilical cord blood (HUCB) cells: Implications for brain repair

The potential therapeutic benefits from human umbilical cord blood (HUCB) cells for the treatment of injuries, diseases, and neurodegeneration are becoming increasingly recognized. The transplantation or infusion of cord blood cells in various animal models, such as ischemia/stroke, traumatic brain injury, myocardial infarction, Parkinson's disease, and amyotropic lateral sclerosis, has resulted in amelioration of behavioral deficits, and with some diseases, a prolonged lifespan decreased neuropathology. Previously, we reported the migration of HUCB cells to ischemic brain supernatant (tissue extracts) is time-dependent, and the expression of specific chemokines responds to this migration pattern. The mechanism(s) responsible for these effects are unknown. The expression of cytokines and chemokines produced by HUCB cells (under various culturing conditions) was investigated in this study. IL-8, MCP-1, and IL-1alpha were consistently expressed by the HUCB mononuclear cells regardless of the culture condition. These results provide insights to factors that may be partially responsible for the functional improvements seen in the animal models of injury investigating the therapeutic use of HUCB cells.

Progenitor cells in liver regeneration: molecular responses controlling their activation and expansion

Although normally quiescent, the adult mammalian liver possesses a great capacity to regenerate after different types of injuries in order to restore the lost liver mass and ensure maintenance of the multiple liver functions. Major players in the regeneration process are mature residual cells, including hepatocytes, cholangiocytes and stromal cells. However, if the regenerative capacity of mature cells is impaired by liver-damaging agents, hepatic progenitor cells are activated and expand into the liver parenchyma. Upon transit amplification, the progenitor cells may generate new hepatocytes and biliary cells to restore liver homeostasis. In recent years, hepatic progenitor cells have been the subject of increasing interest due to their therapeutic potential in numerous liver diseases as alternative or supportive/complementary tools to liver transplantation. While the first investigations on hepatic progenitor cells have focused on their origin and phenotypic characterization, recent attention has focused on the influence of the hepatic microenvironment on their activation and proliferation. This microenvironment comprises the extracellular matrix, epithelial and non-epithelial resident liver cells, and recruited inflammatory cells as well as the variety of growth-modulating molecules produced and/or harboured by these elements. The cellular and molecular responses to different regenerative stimuli seem to depend on the injury inflicted and consequently on the molecular microenvironment created in the liver by a certain insult. This review will focus on molecular responses controlling activation and expansion of the hepatic progenitor cell niche, emphasizing similarities and differences in the microenvironments orchestrating regeneration by recruitment of progenitor cell populations or by replication of mature cells.

Identification and Characterization of U83A Viral Chemokine, a Broad and Potent β-Chemokine Agonist for Human CCRs with Unique Selectivity and Inhibition by Spliced Isoform

Leukotropic human herpesvirus 6 (HHV-6) establishes a persistent infection associated with inflammatory diseases and encodes chemokines that could chemoattract leukocytes for infection or inflammation. HHV-6 variant A encodes a distant chemokine homolog, U83A, and a polymorphism promoting a secreted form was identified. U83A and three N-terminal modifications were expressed and purified, and activities were compared with a spliced truncated isoform, U83A-Npep. U83A efficiently and potently induced calcium mobilization in cells expressing single human CCR1, CCR4, CCR6, or CCR8, with EC50 values <10 nM. U83A also induced chemotaxis of Th2-like leukemic cells expressing CCR4 and CCR8. High-affinity binding, 0.4 nM, was demonstrated to CCR1 and CCR5 on monocytic/macrophage cells, and pretreatment with U83A or modified forms could block responses for endogenous ligands. U83A-Npep acted only as antagonist, efficiently blocking binding of CCL3 to CCR1 or CCR5 on differentiated monocytic/macrophage leukemic cells. Furthermore, CCL3 induction of calcium signaling via CCR1 and CCL1 induced chemotaxis via CCR8 in primary human leukocytes was inhibited. Thus, this blocking by the early expressed U83A-Npep could mediate immune evasion before finishing the replicative cycle. However, late in infection, when full-length U83A is made, chemoattraction of CCR1-, CCR4-, CCR5-, CCR6-, and CCR8-bearing monocytic/macrophage, dendritic, and T lymphocyte cells can facilitate dissemination via lytic and latent infection of these cells. This has further implications for neuroinflammatory diseases such as multiple sclerosis, where both cells bearing CCR1/CCR5 plus their ligands, as well as HHV-6A, have been linked. Applications also discussed include novel vaccines/immunotherapeutics for cancer and HIV as well as anti-inflammatories.

Synergy in cytokine and chemokine networks amplifies the inflammatory response

The inflammatory response is a highly co-ordinated process involving multiple factors acting in a complex network as stimulators or inhibitors. Upon infection, the sequential release of exogenous agents (e.g. bacterial and viral products) and induction of endogenous mediators (e.g. cytokines and chemokines) contribute to the recruitment of circulating leukocytes to the inflamed tissue. Microbial products trigger multiple cell types to release cytokines, which in turn are potent inducers of chemokines. Primary cytokines act as endogenous activators of the immune response, whereas inducible chemokines act as secondary mediators to attract leukocytes. Interaction between exogenous and endogenous mediators thus enhances the inflammatory response. In this review, the synergistic interaction between cytokines to induce chemokine production and the molecular mechanisms of the cooperation amongst co-induced chemokines to further increase leukocyte recruitment to the site of inflammation are discussed.

Human bone marrow stromal cells express a distinct set of biologically functional chemokine receptors

Stromal cells isolated from bone marrow (BMSCs), often referred to as mesenchymal stem cells, are currently under investigation for a variety of therapeutic applications. However, limited data are available regarding receptors that can influence their homing to and positioning within the bone marrow. In the present study, we found that second passage BMSCs express a unique set of chemokine receptors: three CC chemokine receptors (CCR1, CCR7, and CCR9) and three CXC chemokine receptors (CXCR4, CXCR5, and CXCR6). BMSCs cultured in serum-free medium secrete several chemokine ligands (CCL2, CCL4, CCL5, CCL20, CXCL12, CXCL8, and CX3CL1). The surface-expressed chemokine receptors were functional by several criteria. Stimulation of BMSCs with chemokine ligands triggers phosphorylation of the mitogen-activated protein kinase (e.g., extracellular signal-related kinase [ERK]-1 and ERK-2) and focal adhesion kinase signaling pathways. In addition, CXCL12 selectively activates signal transducer and activator of transcription (STAT)-5 whereas CCL5 activates STAT-1. In cell biologic assays, all of the chemokines tested stimulate chemotaxis of BMSCs, and CXCL12 induces cytoskeleton F-actin polymerization. Studies of culture-expanded BMSCs, for example, 12-16 passages, indicate loss of surface expression of all chemokine receptors and lack of chemotactic response to chemokines. The loss in chemokine receptor expression is accompanied by a decrease in expression of adhesion molecules (ICAM-1, ICAM-2, and vascular cell adhesion molecule 1) and CD157, while expression of CD90 and CD105 is maintained. The change in BMSC phenotype is associated with slowing of cell growth and increased spontaneous apoptosis. These findings suggest that several chemokine axes may operate in BMSC biology and may be important parameters in the validation of cultured BMSCs intended for cell therapy.

A310 helical turn is essential for the proliferation-inhibiting properties of macrophage inflammatory protein-1 alpha (CCL3)

Despite possessing marked structural similarities, the chemokines macrophage inflammatory protein-1alpha (MIP-1alpha; CCL3) and RANTES (CCL5) display differential activity in hematopoietic progenitor-cell-inhibitory assays, with MIP-1alpha being active and RANTES inactive in this context. We have sought to identify the key structural determinants of this property of MIP-1alpha. This has involved constructing MIP-1alpha/RANTES chimeras by swapping structural domains between the 2 proteins. Results indicate that, in contrast to other chemokine functions, neither the N nor the C termini are key determinants of inhibitory activity. The motif that appears to be most important for this activity lies between the second and fourth cysteines of MIP-1alpha and further domain swap analysis has narrowed this down to the 3 10 helical turn preceding the first beta-strand in MIP-1alpha. More detailed analysis has highlighted the role played by a specific dipeptide motif in the proliferation-inhibitory activity of chemokines. The involvement of the 3 10 helical-turn motif in chemokine function is unprecedented and this study therefore identifies a novel, functionally essential motif within chemokines. In addition, this study further attests to the alternative mechanisms of action used by MIP-1alpha in inhibition of hematopoietic progenitor-cell proliferation and regulation of leukocyte migration.

Stroke-induced Migration of Human Umbilical Cord Blood Cells: Time Course and Cytokines

The therapeutic window for treatment of individuals after stroke is narrow, regardless of the treatment regime; extension of this window would provide a major therapeutic advance. In prior reports, we demonstrated significant improvements in the behavioral defects of rats that received human umbilical cord blood (HUCB) cells 24 h after a middle cerebral arterial occlusion. These effects paralleled the recruitment of these cells to the site of tissue damage. While the administration of HUCB cells 24 h after stroke was effective, the optimal time to administer these cells after stroke has not been established. Here, we investigated the migration of HUCB cells to ischemic tissue extracts. After ischemic assault, brain tissue was homogenized, and the supernatants were assayed for their ability to attract HUCB mononuclear cells as well as for levels of several cytokines. We demonstrate increased migratory activity of HUCB cells toward the extracts harvested at 24-72 h after stroke. The extracts possessed increased levels of certain cytokines and chemokines, suggesting their participation in HUCB cell migration. The results from this study are promising in that the current 3-h therapeutic window for the treatment of stroke victims, using approved anticoagulant treatment, may be extended with the use of HUCB cell therapy 24-72 h post stroke. Last, the chemokines present in the supernatant provide a sound starting point to start examining the mechanisms responsible for the in vivo migration of HUCB cells after the induction of stroke.

CXCR3 polymorphisms associated with risk of asthma

The chemokine (C-X-C motif) receptor 3 (CXCR3) gene, on chromosome Xq13, is known to have critical roles in inflammatory and immune responses. In an effort to discover polymorphisms have been implicated in asthma, we investigated the genetic polymorphisms in CXCR3 to evaluate it as a potential candidate gene for a host genetic study of asthma. Statistical analysis revealed that one SNP in intron 1, c.12+234G > A, showed significant association with the risk of asthma development (P = 0.007, OR = 0.81). By subgroup analyses stratified by gender and atopic status, the genetic effect of c.12+234G > A on asthma was more apparent among male atopic subjects (P = 0.0009, OR = 0.61). Our findings suggest that polymorphisms in CXCR3 might be one of the genetic factors for the risk of asthma development, especially in male atopic subjects. CXCR3 variation/haplotype information identified in this study will provide valuable information and insight into strategies for the control of asthma and its subgroup, atopy.

Involvement of CC chemokine ligand 18 (CCL18) in normal and pathological processes

CC chemokine ligand 18 (CCL18) was originally discovered as pulmonary and activation-regulated chemokine (PARC), dendritic cell (DC)-chemokine 1 (DC-CK1), alternative macrophage activation-associated CC chemokine-1 (AMAC-1), and macrophage inflammatory protein-4 (MIP-4). CCL18 primarily targets lymphocytes and immature DC, although its agonistic receptor remains unknown so far. CCL18 is mainly expressed by a broad range of monocytes/macrophages and DC. A more profound understanding of the various activation programs and functional phenotypes of these producer cells might give a better insight in the proinflammatory versus anti-inflammatory role of this CC chemokine. It is interesting that CCL18 is constitutively present at high levels in human plasma and likely contributes to the physiological homing of lymphocytes and DC and to the generation of primary immune responses. Furthermore, enhanced CCL18 production has been demonstrated in several diseases, including various malignancies and inflammatory joint, lung, and skin diseases. The lack of a rodent counterpart for human CCL18 sets all hope on primate animal models to further elucidate the importance of CCL18 in vivo. This review will address these different aspects in more detail.

Hematopoietic stem cells from NOD mice exhibit autonomous behavior and a competitive advantage in allogeneic recipients

Type 1 diabetes is a systemic autoimmune disease that can be cured by transplantation of hematopoietic stem cells (HSCs) from disease-resistant donors. Nonobese diabetic (NOD) mice have a number of features that distinguish them as bone marrow transplant recipients that must be understood prior to the clinical application of chimerism to induce tolerance. In the present studies, we characterized NOD HSCs, comparing their engraftment characteristics to HSCs from disease-resistant strains. Strikingly, NOD HSCs are significantly enhanced in engraftment potential compared with HSCs from disease-resistant donors. Unlike HSCs from disease-resistant strains, they do not require graft-facilitating cells to engraft in allogeneic recipients. Additionally, they exhibit a competitive advantage when coadministered with increasing numbers of syngeneic HSCs, produce significantly more spleen colony-forming units (CFU-Ss) in vivo in allogeneic recipients, and more granulocyte macrophage–colony-forming units (CFU-GMs) in vitro compared with HSCs from disease-resistant controls. NOD HSCs also exhibit significantly enhanced chemotaxis to a stromal cell–derived factor 1 (SDF-1) gradient and adhere significantly better on primary stroma. This enhanced engraftment potential maps to the insulin-dependent diabetes locus 9 (Idd9) locus, and as such the tumor necrosis factor (TNF) receptor family as well as ski/sno genes may be involved in the mechanism underlying the autonomy of NOD HSCs. These findings may have important implications to understand the evolution of autoimmune disease and impact on potential strategies for cure.

MIP-1alpha induces differential MAP kinase activation and IkappaB gene expression in human B lymphocytes

The chemokine macrophage inflammatory protein-1alpha (MIP-1alpha) stimulates migration of B cells and affects B cell immunoglobulin production. However, the molecular mechanisms by which MIP-1alpha modulates these biologic effects have not been completely defined. Previously, we demonstrated that treatment of B cells with MIP-1alpha induced the transcription factor, nuclear factor (NF)-kappaB, to bind to DNA, concomitant with the degradation of IkappaBalpha, a cytoplasmic inhibitor of NF-kappaB activation. Here, we report that MIP-1alpha treatment of tonsil B cells induced IkappaB gene expression that was dependent on MIP-1alpha-mediated activation of a pathway(s) involving NF-kappaB and phosphatidylinositol-3 kinase (PI3K). The NF-kappaB pathway is understood to be controlled in an autoregulatory fashion, so expression of IkappaB is thought to provide a means by which B cells modulate this pathway after stimulation with MIP-1alpha. Although the idea of NF-kappaB autoregulation is not novel, this is the first report to suggest the regulation of B cell gene expression by MIP-1alpha. In addition, we observed the activation of Jun N-terminal kinase (JNK) and p38 mitogenic-activated protein kinase (MAPK), but not extracellular signal-related kinase (ERK) in response to MIP-1alpha. Although p38 and NF-kappaB activity were both necessary for B cell migration, IkappaB gene expression was not affected by p38 inhibition, suggesting that p38 is involved in a separate MIP-1alpha-mediated signal transduction pathway.

Identification of murine and human XCP1 genes as C/EBP-epsilon-dependent members of FIZZ/Resistin gene family

The CCAAT enhancer binding protein epsilon (C/EBP-epsilon) transcription factor is expressed predominantly in granulocytes. Mice with a disruption of the C/EBP-epsilon gene fail to produce mature granulocytes and eosinophils. Cells derived from the peritoneal exudates of C/EBP-epsilon -/- mice lack the expression of a number of chemokines and chemokine receptor genes. We have found a novel C/EBP-epsilon-dependent promyelocyte-specific gene, mXCP1. mXCP1 belongs to a family of XCP/FIZZ/Resistin genes, which includes four murine genes and two human genes, hXCP1 and hXCP2. These genes have four exons and encode short secreted proteins sharing a ten-cysteine motif. Murine mXCP1, mXCP2 and mXCP3 genes map to murine chromosome 16 and mXCP4 is positioned on chromosome 8; the hXCP1 and hXCP2 genes are located at homologous regions of chromosomes 3 and 19. Introduction of an inducible C/EBP-epsilon gene into the NIH3T3 and myeloid cells from C/EBP-epsilon-null mice line revealed that the conditional expression of C/EBP-epsilon induced mXCP1. The HXCP1 gene was identified as a C/EBP-epsilon-dependent regulatory homologue of mXCP1. The expression data for other members of XCP/FIZZ gene family are presented. Further studies indicate that XCP1 is a secreted protein that is chemotactic to myeloid cells from C/EBP-epsilon-null mice and is able to interact directly with alpha-defensin.

The bone marrow is akin to skin: HCELL and the biology of hematopoietic stem cell homing

The recent findings that adult stem cells are capable of generating new blood vessels and parenchymal cells within tissues they have colonized has raised immense optimism that these cells may provide functional recovery of damaged organs. The use of adult stem cells for regenerative therapy poses the challenging task of getting these cells into the requisite sites with minimum morbidity and maximum efficiency. Ideally, tissue-specific colonization could be achieved by introducing the stem cells intravascularly and exploiting the native physiologic processes governing cell trafficking. Critical to the success of this approach is the use of stem cells bearing appropriate membrane molecules that mediate homing from vascular to tissue compartments. Hematopoietic stem cells (HSC) express a novel glycoform of CD44 known as hematopoietic cell E-/L-selectin ligand (HCELL). This molecule is the most potent E-selectin ligand natively expressed on any human cell. This article reviews our current understanding of the molecular basis of HSC homing and will describe the fundamental "roll" of HCELL in opening the avenues for efficient HSC trafficking to the bone marrow, the skin and other extramedullary sites.

Synergy between proinflammatory ligands of G protein-coupled receptors in neutrophil activation and migration

The chemokine dose and the time period during which the chemotactic gradient is established determine the number of leukocytes that infiltrate inflamed tissues. At suboptimal chemokine concentrations, neutrophils may require a priming agent or a second stimulus for full activation. An interesting mode of cooperative action to reach maximal migration is synergy between chemokines. This was first observed between the plasma CC chemokine regakine-1 and the tissue CXC chemokine ligand interleukin-8 (IL-8/CXCL8) in neutrophil chemotaxis. Addition of antibodies against IL-8 or regakine-1 in the Boyden microchamber assay abrogated this synergy. Other CC chemokines, such as CC chemokine ligand-2 monocyte chemotactic protein-1 (MCP-1/CCL2), MCP-2 (CCL8), and MCP-3 (CCL7) as well as the CXC chemokine receptor-4 (CXCR4) agonist stromal cell-derived factor-1alpha (SDF-1alpha/CXCL12), also dose-dependently enhanced neutrophil chemotaxis toward a suboptimal concentration of IL-8. These chemokines synergized equally well with the anaphylatoxin C5a in neutrophil chemotaxis. Alternatively, IL-8 and C5a did not synergize with an inactive precursor form of CXCL7, connective tissue-activating peptide-III/CXCL7, or the chemoattractant neutrophil-activating peptide-2/CXCL7. In the chemotaxis assay under agarose, MCP-3 dose-dependently increased the migration distance of neutrophils toward IL-8. In addition, the combination of IL-8 and MCP-3 resulted in enhanced neutrophil shape change. AMD3100, a specific CXCR4 inhibitor, reduced the synergistic effect between SDF-1alpha and IL-8 significantly. SDF-1alpha, but not MCP-1, synergized with IL-8 in chemotaxis with CXCR1-transfected, CXCR4-positive Jurkat cells. Thus, proinflammatory chemokines (IL-8, MCP-1), coinduced during infection in the tissue, synergize with each other or with constitutive chemokines (regakine-1, SDF-1alpha) to enhance the inflammatory response.

The stromal cell-derived factor-1alpha/CXCR4 ligand-receptor axis is critical for progenitor survival and migration in the pancreas

The SDF-1α/CXCR4 ligand/chemokine receptor pair is required for appropriate patterning during ontogeny and stimulates the growth and differentiation of critical cell types. Here, we demonstrate SDF-1α and CXCR4 expression in fetal pancreas. We have found that SDF-1α and its receptor CXCR4 are expressed in islets, also CXCR4 is expressed in and around the proliferating duct epithelium of the regenerating pancreas of the interferon (IFN) γ–nonobese diabetic mouse. We show that SDF-1α stimulates the phosphorylation of Akt, mitogen-activated protein kinase, and Src in pancreatic duct cells. Furthermore, migration assays indicate a stimulatory effect of SDF-1α on ductal cell migration. Importantly, blocking the SDF-1α/CXCR4 axis in IFNγ-nonobese diabetic mice resulted in diminished proliferation and increased apoptosis in the pancreatic ductal cells. Together, these data indicate that the SDF-1α–CXCR4 ligand receptor axis is an obligatory component in the maintenance of duct cell survival, proliferation, and migration during pancreatic regeneration.

PARC/CCL18 is a plasma CC chemokine with increased levels in childhood acute lymphoblastic leukemia

Chemokines play an important role in leukocyte mobilization, hematopoiesis, and angiogenesis. Tissue-specific expression of particular chemokines also influences tumor growth and metastasis. Here, the CC chemokine pulmonary and activation-regulated chemokine (PARC)/CCL18 was measured in pediatric patients with acute lymphoblastic leukemia (ALL) or acute myeloid leukemia (AML). Surprisingly, PARC immunoreactivity was consistently detected in plasma from healthy donors. After purification to homogeneity, the presence of intact PARC (1-69) and processed PARC (1-68) in normal human plasma was confirmed by sequence and mass spectrometry analysis. Furthermore, PARC serum levels were significantly increased in children with T-ALL and prepreB-ALL compared to control serum samples, whereas serum levels in AML and preB-ALL patients were not significantly different from controls. In contrast, the hemofiltrate CC chemokine-1 (HCC-1)/CCL14 was not found to be a biomarker in any of these patients' strata, whereas the cytokine interleukin-6 (IL-6) was significantly decreased in AML and prepreB-ALL. Stimulated leukocytic cell lines or lymphoblasts from patients produced IL-8/CXCL8 or macrophage inflammatory protein-1alpha (MIP-1alpha/CCL3) but not PARC, not even after IL-4 or IL-10 treatment. However, PARC was produced by superantigen or IL-4 stimulated monocytes co-cultured with lymphocytes or lymphoblastic cells. Serum PARC levels thus constitute a novel leukemia marker, possibly reflecting tumor/host cell interactions in the circulation.

The CC chemokine CCL20 and its receptor CCR6

CCL20, alternatively named liver and activation-regulated chemokine (LARC), macrophage inflammatory protein-3alpha (MIP-3alpha) or Exodus-1, is the only chemokine known to interact with CC chemokine receptor 6 (CCR6), a property shared with the antimicrobial beta-defensins. The ligand-receptor pair CCL20-CCR6 is responsible for the chemoattraction of immature dendritic cells (DC), effector/memory T-cells and B-cells and plays a role at skin and mucosal surfaces under homeostatic and inflammatory conditions, as well as in pathology, including cancer and rheumatoid arthritis. In this review, the discovery, the gene and protein structure, the in vitro biological activities, the cell and inducer specific expression and the tissue distribution of CCL20 and CCR6 are discussed.

Peripheral blood stem cell mobilization. A role for CXC chemokines

Chemokines induce rapid hematopoietic stem and progenitor cell mobilization and synergize with hematopoietic cytokines in mobilizing stem and progenitor cells. These proteins alone and in combination offer new paradigms for autologous and allogeneic peripheral blood stem cell transplantation (PBSCT). The mechanisms responsible for hematopoietic stem cell (HSC) mobilization either with growth factors or chemokines are largely unknown, but a better understanding of these mechanisms will permit the development of novel, more rapid and efficacious regimens. Studies presented herein indicate that the CXCR2 chemokine receptor that interacts with selective chemokine ligands, particularly GRObeta/CXCL2 and GRObeta-T, may be the dominant receptor mediating hematopoietic cell mobilization, and that polymorphonuclear neutrophils may be the primary CXCR2 expressing target cell for stem and progenitor cell mobilization.