Dysregulated Expression of the Nuclear Exosome Targeting Complex Component Rbm7 in Nonhematopoietic Cells Licenses the Development of Fibrosis.

Fibrosis is an incurable disorder of unknown etiology. Segregated-nucleus-containing atypical monocytes (SatMs) are critical for the development of fibrosis. Here we examined the mechanisms that recruit SatMs to pre-fibrotic areas. A screen based on cytokine expression in the fibrotic lung revealed that the chemokine Cxcl12, which is produced by apoptotic nonhematopoietic cells, was essential for SatM recruitment. Analyses of lung tissues at fibrosis onset showed increased expression of Rbm7, a component of the nuclear exosome targeting complex. Rbm7 deletion suppressed bleomycin-induced fibrosis and at a cellular level, suppressed apoptosis of nonhematopoietic cells. Mechanistically, Rbm7 bound to noncoding (nc)RNAs that form subnuclear bodies, including Neat1 speckles. Dysregulated expression of Rbm7 resulted in the nuclear degradation of Neat1 speckles, the dispersion of the DNA repair protein BRCA1, and the triggering of apoptosis. Thus, Rbm7 in epithelial cells plays a critical role in the development of fibrosis by regulating ncRNA decay and thereby the production of chemokines that recruit SatMs.

Acute malaria suppresses the B lymphocytic niche in the bone marrow through the alteration of CXCL12-abundant reticular cells.

Bone marrow is a dynamic organ composed of stem cells that constantly receive signals from stromal cells and other hematopoietic cells in the niches of the bone marrow to maintain hematopoiesis and generate immune cells. Perturbation of the bone marrow microenvironment by infection and inflammation affects hematopoiesis and may affect immune cell development. Little is known about the effect of malaria on the bone marrow stromal cells that govern the hematopoietic stem cell (HSC) niche. In this study, we demonstrate that the mesenchymal stromal CXCL12-abundant reticular (CAR) cell population is reduced during acute malaria infection. The reduction of CXCL12 and interleukin-7 signals in the bone marrow impairs the lymphopoietic niche, leading to the depletion of common lymphoid progenitors, B cell progenitors, and mature B cells, including plasma cells in the bone marrow. We found that interferon-γ (IFNγ) is responsible for the upregulation of Sca1 on CAR cells, yet the decline in CAR cell and B cell populations in the bone marrow is IFNγ-independent. In contrast to the decline in B cell populations, HSCs and multipotent progenitors increased with the expansion of myelopoiesis and erythropoiesis, indicating a bias in the differentiation of multipotent progenitors during malaria infection. These findings suggest that malaria may affect host immunity by modulating the bone marrow niche.

Monocytes-macrophages that express α-smooth muscle actin preserve primitive hematopoietic cells in the bone marrow.

Hematopoietic stem and progenitor cells (HSPCs) are regulated by various bone marrow stromal cell types. Here we identified rare activated bone marrow monocytes and macrophages with high expression of α-smooth muscle actin (α-SMA) and the cyclooxygenase COX-2 that were adjacent to primitive HSPCs. These myeloid cells resisted radiation-induced cell death and further upregulated COX-2 expression under stress conditions. COX-2-derived prostaglandin E(2) (PGE(2)) prevented HSPC exhaustion by limiting the production of reactive oxygen species (ROS) via inhibition of the kinase Akt and higher stromal-cell expression of the chemokine CXCL12, which is essential for stem-cell quiescence. Our study identifies a previously unknown subset of α-SMA(+) activated monocytes and macrophages that maintain HSPCs and protect them from exhaustion during alarm situations.

CXCL12 Neutralizing Antibody Promotes Hair Growth in Androgenic Alopecia and Alopecia Areata.

We had previously investigated the expression and functional role of C-X-C Motif Chemokine Ligand 12 (CXCL12) during the hair cycle progression. CXCL12 was highly expressed in stromal cells such as dermal fibroblasts (DFs) and inhibition of CXCL12 increased hair growth. Therefore, we further investigated whether a CXCL12 neutralizing antibody (αCXCL12) is effective for androgenic alopecia (AGA) and alopecia areata (AA) and studied the underlying molecular mechanism for treating these diseases. In the AGA model, CXCL12 is highly expressed in DFs. Subcutaneous (s.c.) injection of αCXCL12 significantly induced hair growth in AGA mice, and treatment with αCXCL12 attenuated the androgen-induced hair damage in hair organ culture. Androgens increased the secretion of CXCL12 from DFs through the androgen receptor (AR). Secreted CXCL12 from DFs increased the expression of the AR and C-X-C Motif Chemokine Receptor 4 (CXCR4) in dermal papilla cells (DPCs), which induced hair loss in AGA. Likewise, CXCL12 expression is increased in AA mice, while s.c. injection of αCXCL12 significantly inhibited hair loss in AA mice and reduced the number of CD8+, MHC-I+, and MHC-II+ cells in the skin. In addition, injection of αCXCL12 also prevented the onset of AA and reduced the number of CD8+ cells. Interferon-γ (IFNγ) treatment increased the secretion of CXCL12 from DFs through the signal transducer and activator of transcription 3 (STAT3) pathway, and αCXCL12 treatment protected the hair follicle from IFNγ in hair organ culture. Collectively, these results indicate that CXCL12 is involved in the progression of AGA and AA and antibody therapy for CXCL12 is promising for hair loss treatment.

Mycobacterial infection-induced miR-206 inhibits protective neutrophil recruitment via the CXCL12/CXCR4 signalling axis.

Pathogenic mycobacteria actively dysregulate protective host immune signalling pathways during infection to drive the formation of permissive granuloma microenvironments. Dynamic regulation of host microRNA (miRNA) expression is a conserved feature of mycobacterial infections across host-pathogen pairings. Here we examine the role of miR-206 in the zebrafish model of Mycobacterium marinum infection, which allows investigation of the early stages of granuloma formation. We find miR-206 is upregulated following infection by pathogenic M. marinum and that antagomir-mediated knockdown of miR-206 is protective against infection. We observed striking upregulation of cxcl12a and cxcr4b in infected miR-206 knockdown zebrafish embryos and live imaging revealed enhanced recruitment of neutrophils to sites of infection. We used CRISPR/Cas9-mediated knockdown of cxcl12a and cxcr4b expression and AMD3100 inhibition of Cxcr4 to show that the enhanced neutrophil response and reduced bacterial burden caused by miR-206 knockdown was dependent on the Cxcl12/Cxcr4 signalling axis. Together, our data illustrate a pathway through which pathogenic mycobacteria induce host miR-206 expression to suppress Cxcl12/Cxcr4 signalling and prevent protective neutrophil recruitment to granulomas.

CXCL12 secretion by bone marrow stromal cells is dependent on cell contact and mediated by connexin-43 and connexin-45 gap junctions.

The chemokine CXCL12 is essential for the function of hematopoietic stem and progenitor cells. Here we report that secretion of functional CXCL12 from human bone marrow stromal cells (BMSCs) was a cell contact-dependent event mediated by connexin-43 (Cx43) and Cx45 gap junctions. Inhibition of connexin gap junctions impaired the secretion of CXCL12 and homing of leukocytes to mouse bone marrow. Purified human CD34(+) progenitor cells did not adhere to noncontacting BMSCs, which led to a much smaller pool of immature cells. Calcium conduction activated signaling by cAMP-protein kinase A (PKA) and induced CXCL12 secretion mediated by the GTPase RalA. Cx43 and Cx45 additionally controlled Cxcl12 transcription by regulating the nuclear localization of the transcription factor Sp1. We suggest that BMSCs form a dynamic syncytium via connexin gap junctions that regulates CXC12 secretion and the homeostasis of hematopoietic stem cells.

The multifaceted roles of the chemokines CCL2 and CXCL12 in osteophilic metastatic cancers.

Breast and prostate cancers have a great propensity to metastasize to long bones. The development of bone metastases is life-threatening, incurable, and drastically reduces patients' quality of life. The chemokines CCL2 and CXCL12 and their respective receptors, CCR2 and CXCR4, are central instigators involved in all stages leading to cancer cell dissemination and secondary tumor formation in distant target organs. They orchestrate tumor cell survival, growth and migration, tumor invasion and angiogenesis, and the formation of micrometastases in the bone marrow. The bone niche is of particular importance in metastasis formation, as it expresses high levels of CCL2 and CXCL12, which attract tumor cells and contribute to malignancy. The limited number of available effective treatment strategies highlights the need to better understand the pathophysiology of bone metastases and reduce the skeletal tumor burden in patients diagnosed with metastatic bone disease. This review focuses on the involvement of the CCL2/CCR2 and CXCL12/CXCR4 chemokine axes in the formation and development of bone metastases, as well as on therapeutic perspectives aimed at targeting these chemokine-receptor pairs.

HMGB1 promotes CXCL12-dependent egress of murine B cells from Peyer's patches in homeostasis.

High mobility group box-1 protein (HMGB1) is an alarmin that, once released, promotes inflammatory responses, alone and as a complex with the chemokine CXCL12. Here, we report that the HMGB1-CXCL12 complex plays an essential role also in homeostasis by controlling the migration of B lymphocytes. We show that extracellular HMGB1 is critical for the CXCL12-dependent egress of B cells from the Peyer's patches (PP). This promigratory function of the complex was restricted to the PPs, since HMGB1 was not required for B-cell migratory processes in other locations. Accordingly, we detected higher constitutive levels of the HMGB1-CXCL12 complex in PPs than in other lymphoid organs. HMGB1-CXCL12 in vivo inhibition was associated with a reduced basal IgA production in the gut. Collectively, our results demonstrate a role for the HMGB1-CXCL12 complex in orchestrating B-cell trafficking in homeostasis, and provide a novel target to control lymphocyte migration in mucosal immunity.

CXCR4 acts as a costimulator during thymic beta-selection.

Passage through the beta-selection developmental checkpoint requires productive rearrangement of segments of the T cell antigen receptor-beta gene (Tcrb) and formation of a pre-TCR on the surface of CD4(-)CD8(-) thymocytes. How other receptors influence betabeta-selection is less well understood. Here we define a new role for the chemokine receptor CXCR4 during T cell development. CXCR4 functionally associated with the pre-TCR and influenced beta-selection by regulating the steady-state localization of immature thymocytes in thymic subregions, by facilitating optimal pre-TCR-induced survival signals, and by promoting thymocyte proliferation. We also characterize functionally relevant signaling molecules downstream of CXCR4 and the pre-TCR in thymocytes. Our data designate CXCR4 as a costimulator of the pre-TCR during beta-selection.

Novel insights into the pathogenesis of lung fibrosis: the RBM7-NEAT1-CXCL12-SatM axis at fibrosis onset.

Fibrosis is a life-threatening disorder with significant morbidity and mortality and is caused by excessive formation of connective tissue that can affect several important organs. Fibrosis in organ tissues is caused by an abnormal wound-healing process from repeated injuries. In our recent study using a mouse model of bleomycin-induced lung fibrosis, we examined the role of RNA-binding motif protein 7 (RBM7) on the development of lung fibrosis. RBM7 is up-regulated in the injured lung epithelium and disturbs normal epithelial cell repair and regeneration by promoting apoptosis of damaged epithelial cells. RBM7 causes the decay of nuclear-enriched abundant transcript 1 (NEAT1), which results in apoptosis of lung epithelial cells. These apoptotic cells then produce C-X-C motif chemokine ligand 12 (CXCL12), which leads to the recruitment of a fibrosis-promoting monocyte population called segregated-nucleus-containing atypical monocytes (SatM) to the damaged area, followed by the initiation and promotion of lung fibrosis. Here, we review recent insights into the cross-talk between lung parenchymal cells and hematopoietic cells during the development of pulmonary fibrosis.

Reactive Oxidative Species-Modulated Ca2+ Release Regulates ß2 Integrin Activation on CD4+ CD28null T Cells of Acute Coronary Syndrome Patients.

The number and activity of T cell subsets in the atherosclerotic plaques are critical for the prognosis of patients with acute coronary syndrome. ß2 Integrin activation is pivotal for T cell recruitment and correlates with future cardiac events. Despite this knowledge, differential regulation of adhesiveness in T cell subsets has not been explored yet. In this study, we show that in human T cells, SDF-1α-mediated ß2 integrin activation is driven by a, so far, not-described reactive oxidative species (ROS)-regulated calcium influx. Furthermore, we show that CD4+CD28null T cells represent a highly reactive subset showing 25-fold stronger ß2 integrin activation upon SDF-1α stimulation compared with CD28+ T cells. Interestingly, ROS-dependent Ca release was much more prevalent in the pathogenetically pivotal CD28null subset compared with the CD28+ T cells, whereas the established mediators of the classical pathways for ß2 integrin activation (PKC, PI3K, and PLC) were similarly activated in both T cell subsets. Thus, interference with the calcium flux attenuates spontaneous adhesion of CD28null T cells from acute coronary syndrome patients, and calcium ionophores abolished the observed differences in the adhesion properties between CD28+ and CD28null T cells. Likewise, the adhesion of these T cell subsets was indistinguishable in the presence of exogenous ROS/H2O2 Together, these data provide a molecular explanation of the role of ROS in pathogenesis of plaque destabilization.

Skin-resident natural killer T cells participate in cutaneous allergic inflammation in atopic dermatitis.

BACKGROUND: Natural killer T (NKT) cells are unconventional T cells that bridge innate and adaptive immunity. NKT cells have been implicated in the development of atopic dermatitis (AD). OBJECTIVE: We aimed to investigate the role of NKT cells in AD development, especially in skin. METHODS: Global proteomic and transcriptomic analyses were performed by using skin and blood from human healthy-controls and patients with AD. Levels of CXCR4 and CXCL12 expression in skin NKT cells were analyzed in human AD and mouse AD models. By using parabiosis and intravital imaging, the role of skin CXCR4+ NKT cells was further evaluated in models of mice with AD by using CXCR4-conditionally deficient or CXCL12 transgenic mice. RESULTS: CXCR4 and its cognate ligand CXCL12 were significantly upregulated in the skin of humans with AD by global transcriptomic and proteomic analyses. CXCR4+ NKT cells were enriched in AD skin, and their levels were consistently elevated in our models of mice with AD. Allergen-induced NKT cells participate in cutaneous allergic inflammation. Similar to tissue-resident memory T cells, the predominant skin NKT cells were CXCR4+ and CD69+. Skin-resident NKT cells uniquely expressed CXCR4, unlike NKT cells in the liver, spleen, and lymph nodes. Skin fibroblasts were the main source of CXCL12. CXCR4+ NKT cells preferentially trafficked to CXCL12-rich areas, forming an enriched CXCR4+ tissue-resident NKT cells/CXCL12+ cell cluster that developed in acute and chronic allergic inflammation in our models of mice with AD. CONCLUSIONS: CXCR4+ tissue-resident NKT cells may form a niche that contributes to AD, in which CXCL12 is highly expressed.

The CXCL12-CXCR4/CXCR7 axis as a mechanism of immune resistance in gastrointestinal malignancies.

Single agent checkpoint inhibitor therapy has not been effective for most gastrointestinal solid tumors, but combination therapy with drugs targeting additional immunosuppressive pathways is being attempted. One such pathway, the CXCL12-CXCR4/CXCR7 chemokine axis, has attracted attention due to its effects on tumor cell survival and metastasis as well as immune cell migration. CXCL12 is a small protein that functions in normal hematopoietic stem cell homing in addition to repair of damaged tissue. Binding of CXCL12 to CXCR4 leads to activation of G protein signaling kinases such as P13K/mTOR and MEK/ERK while binding to CXCR7 leads to ß-arrestin mediated signaling. While some gastric and colorectal carcinoma cells have been shown to make CXCL12, the primary source in pancreatic cancer and peritoneal metastases is cancer-associated fibroblasts. Binding of CXCL12 to CXCR4 and CXCR7 on tumor cells leads to anti-apoptotic signaling through Bcl-2 and survivin upregulation, as well as promotion of the epithelial-to-mesechymal transition through the Rho-ROCK pathway and alterations in cell adhesion molecules. High levels of CXCL12 seen in the bone marrow, liver, and spleen could partially explain why these are popular sites of metastases for many tumors. CXCL12 is a chemoattractant for lymphocytes at lower levels, but becomes chemorepellant at higher levels; it is unclear exactly what gradient exists in the tumor microenvironment and how this influences tumor-infiltrating lymphocytes. AMD3100 (Plerixafor or Mozobil) is a small molecule CXCR4 antagonist and is the most frequently used drug targeting the CXCL12-CXCR4/CXCR7 axis in clinical trials for gastrointestinal solid tumors currently. Other small molecules and monoclonal antibodies against CXCR4 are being trialed. Further understanding of the CXCL12- CXCR4/CXCR7 chemokine axis in the tumor microenvironment will allow more effective targeting of this pathway in combination immunotherapy.

Growth Factor-like Gene Regulation Is Separable from Survival and Maturation in Antibody-Secreting Cells.

Recurrent mutational activation of the MAP kinase pathway in plasma cell myeloma implicates growth factor-like signaling responses in the biology of Ab-secreting cells (ASCs). Physiological ASCs survive in niche microenvironments, but how niche signals are propagated and integrated is poorly understood. In this study, we dissect such a response in human ASCs using an in vitro model. Applying time course expression data and parsimonious gene correlation network analysis (PGCNA), a new approach established by our group, we map expression changes that occur during the maturation of proliferating plasmablast to quiescent plasma cell under survival conditions including the potential niche signal TGF-ß3. This analysis demonstrates a convergent pattern of differentiation, linking unfolded protein response/endoplasmic reticulum stress to secretory optimization, coordinated with cell cycle exit. TGF-ß3 supports ASC survival while having a limited effect on gene expression including upregulation of CXCR4. This is associated with a significant shift in response to SDF1 in ASCs with amplified ERK1/2 activation, growth factor-like immediate early gene regulation and EGR1 protein expression. Similarly, ASCs responding to survival conditions initially induce partially overlapping sets of immediate early genes without sustaining the response. Thus, in human ASCs growth factor-like gene regulation is transiently imposed by niche signals but is not sustained during subsequent survival and maturation.

Macrophage polarization by MSC-derived CXCL12 determines tumor growth.

BACKGROUND: Phenotypic and functional heterogeneity of macrophages is known to be the main reason for their ability to regulate inflammation and promote tumorigenesis. Mesenchymal stem cells (MSCs) are one of the principal cells commonly found in the tumor stromal niche, with capability of macrophage phenotypic switching. The objective of this study was to evaluate the role of C-X-C motif chemokine ligand 12 (CXCL12) produced by marrow-derived MSCs in the phenotypic and functional pattern of bone marrow-derived macrophages (BMDMs). METHODS: First, the CRISPR/Cas9 system was used for the CXCL12 gene knock-out in MSCs. Then, coculture systems were used to investigate the role of MSCsCXCL12-/- and MSCsCXCL12+/+ in determination of macrophage phenotype. To further analyze the role of the MSC-derived CXCL12 niche, cocultures of 4T1 mammary tumor cells and macrophages primed with MSCsCXCL12-/- or MSCsCXCL12+/+ as well as in-vivo limiting dilution assays were performed. RESULTS: Our results revealed that the expression of IL-4, IL-10, TGF-ß and CD206 as M2 markers was significantly increased in macrophages co-cultured with MSCsCXCL12+/+ , whereas the expression of IL-6, TNF-α and iNOS was conversely decreased. The number and size of multicellular tumor spheroids were remarkably higher when 4T1 cells were cocultured with MSCCXCL12+/+-induced M2 macrophages. We also found that the occurrence of tumors was significantly higher in coinjection of 4T1 cells with MSCCXCL12+/+-primed macrophages. Tumor initiating cells were significantly decreased after coinjection of 4T1 cells with macrophages pretreated with MSCsCXCL12-/-. CONCLUSIONS: In conclusion, our findings shed new light on the role of MSC-derived CXCL12 in macrophage phenotypic switching to M2, affecting their function in tumorigenesis.

Identification of a new subset of lymph node stromal cells involved in regulating plasma cell homeostasis.

Antibody-secreting plasma cells (PCs) arise rapidly during adaptive immunity to control infections. The early PCs are retained within the reactive lymphoid organ where their localization and homeostasis rely on extrinsic factors, presumably produced by local niche cells. While myeloid cells have been proposed to form those niches, the contribution by colocalizing stromal cells has remained unclear. Here, we characterized a subset of fibroblastic reticular cells (FRCs) that forms a dense meshwork throughout medullary cords of lymph nodes (LNs) where PCs reside. This medullary FRC type is shown to be anatomically, phenotypically, and functionally distinct from T zone FRCs, both in mice and humans. By using static and dynamic imaging approaches, we provide evidence that medullary FRCs are the main cell type in contact with PCs guiding them in their migration. Medullary FRCs also represent a major local source of the PC survival factors IL-6, BAFF, and CXCL12, besides also producing APRIL. In vitro, medullary FRCs alone or in combination with macrophages promote PC survival while other LN cell types do not have this property. Thus, we propose that this FRC subset, together with medullary macrophages, forms PC survival niches within the LN medulla, and thereby helps in promoting the rapid development of humoral immunity, which is critical in limiting early pathogen spread.

Follicular helper T cells recruit eosinophils into host liver by producing CXCL12 during Schistosoma japonicum infection.

Schistosomiasis affects at least 200 million people in tropical and subtropical areas. The major pathology of schistosomiasis is egg-induced liver granuloma characterized by an eosinophil-rich inflammatory infiltration around the eggs, which subsequently leads to hepatic fibrosis and circulatory impairment in host. However, the mechanisms how eosinophils are recruited into the liver, which are crucial for the better understanding of the mechanisms underlying granuloma formation and control of schistosomiasis, remain unclear. In this study, we showed that follicular helper T (Tfh) cells participate in recruitment of eosinophils into liver partially by producing CXCL12 during schistosome infection. Our findings uncovered a previously unappreciated role of Tfh cells in promotion of the development of liver granuloma in schistosomiasis, making Tfh-CXCL12-eosinophil axis a potential target for intervention of schistosomiasis.

Stromal cell-derived factor-1α predominantly mediates the ameliorative effect of linagliptin against cisplatin-induced testicular injury in adult male rats.

Stromal cell-derived factor-1α (SDF-1α) plays a key role in trafficking of stem cells and regeneration of injured tissue through interaction with its receptor, CXCR4. This study investigated the probable therapeutic effect of linagliptin (LG) against cisplatin (CP)-induced testicular injury and the underlying mechanisms. 12 week old male Sprague-Dawley rats were randomly assigned into 6 groups (n = 10 each) as follow: (i) Control, (ii) LG-treated control, (iii) CP-exposed rats, (iv) CP-exposed rats received LG, (v) CP-exposed rats received AMD3100, as CXCR4 antagonist, and (vi) CP-exposed rats received AMD3100 prior to LG. After 15 days, blood, testes and epididymides were collected for analyses. There were significant increases in both circulatory and testicular levels of SDF-1α in LG-treated rats. Conversely, higher levels of incretin hormones were found in serum but not in testicular tissue of rats, following LG therapy. CP injection significantly reduced body, testicular and epididymal weights of rats, and were restored by LG therapy. Treatment of CP-exposed rats with LG improved the deteriorated testicular architecture, reconstructed spermatogenesis, increased sperm count and quality, and normalized testosterone levels. LG therapy increased gene expression of Lin28a and Mvh, but did not alter the expressions of somatic-related genes. Additionally, LG therapy promoted germ cells survival and proliferation likely via activation of extracellular signal-regulated kinase1/2 (ERK1/2) signaling. These positive effects of LG therapy were almost blunted by administration of AMD3100. These results provided mechanistic insights into the ameliorative effect of LG on CP-induced testicular injury, through activation of SDF-1α/CXCR4 signaling pathway. Our findings suggest that LG can be a promising therapeutic candidate for CP-induced testicular injury.

Physical training prior to myocardial infarction potentializes stem cell therapy, SDF-1/CXCR4 axis activation and inhibits the vasoconstrictor response in hypertensive rats.

Stem cell therapy is a promising strategy for recovering of injured cardiac tissue after acute myocardial infarction. The effects promoted by preventive physical training, beneficial for regeneration, are not yet understood on stem cell homing. In the present study, we evaluated the effect of preventive physical training on cell homing activation and associated mechanisms after acute myocardial infarction and therapy with adipose-derived stem cells in spontaneously hypertensive rats (SHR). Forty female SHR were allocated in sedentary (S), sedentary SHAM (S-SHAM), sedentary AMI (S-AMI), sedentary with cell therapy (S-ICT), aerobically trained (T), trained SHAM (T-SHAM), trained AMI (T-AMI) and trained with cell therapy (S-ICT) groups. Cell therapy was performed through the infusion of 2 × 105 ADSC/0.05 mL at the moment of AMI. Molecular markers of cell homing (SDF-1/CXCR4), inflammatory response (myeloperoxidase and cardiac expression of iNOS, gp91phox and NFkB), vasoconstrictor agents (Ang II and ET-1) and an angiogenesis inducer (VEGF) were measured. Functional capacity and echocardiographic parameters were also evaluated. Preventive physical training associated with cell therapy was able to reduce left ventricle ejection fraction losses in infarcted animals. Results demonstrated activation of the SDF-1/CXCR4 axis by physical training, besides a reduction in vasoconstrictor and systemic inflammatory responses. Physical training prior to AMI was able to induce a cardioprotective effect and optimize the reparative mechanism of cell therapy in an animal model of hypertension.

Dual blockade of CXCL12-CXCR4 and PD-1-PD-L1 pathways prolongs survival of ovarian tumor-bearing mice by prevention of immunosuppression in the tumor microenvironment.

Blockade of immune-checkpoint programmed cell death protein 1 (PD-1) or programmed cell death ligand 1 can enhance effector T-cell responses. However, the lack of response in many patients to checkpoint-inhibitor therapies emphasizes the need for combination immunotherapies to pursue maximal antitumor efficacy. We have previously demonstrated that antagonism of C-X-C chemokine receptor type 4 (CXCR4) by plerixafor (AMD3100) can decrease regulatory T (Treg)-cell intratumoral infiltration. Therefore, a combination of these 2 therapies might increase antitumor effects. Here, we evaluated the antitumor efficacy of AMD3100 and anti-PD-1 (αPD-1) antibody alone or in combination in an immunocompetent syngeneic mouse model of ovarian cancer. We found that AMD3100, a highly specific CXCR4 antagonist, directly down-regulated the expression of both C-X-C motif chemokine 12 (CXCL12) and CXCR4 in vitro and in vivo in tumor cells. AMD3100 and αPD-1 significantly inhibited tumor growth and prolonged the survival of tumor-bearing mice when given as monotherapy. Combination of these 2 agents significantly enhanced antitumor effects compared with single-agent administration. Benefits of tumor control and animal survival were associated with immunomodulation mediated by these 2 agents, which were characterized by increased effector T-cell infiltration, increased effector T-cell function, and increased memory T cells in tumor microenvironment. Intratumoral Treg cells were decreased, and conversion of Treg cells into T helper cells was increased by AMD3100 treatment. Intratumoral myeloid-derived suppressor cells were decreased by the combined treatment, which was associated with decreased IL-10 and IL-6 in the ascites. Also, the combination therapy decreased suppressive leukocytes and facilitated M2-to-M1 macrophage polarization in the tumor. These results suggest that AMD3100 could be used to target the CXCR4-CXCL12 axis to inhibit tumor growth and prevent multifaceted immunosuppression alone or in combination with αPD-1 in ovarian cancer, which could be clinically relevant to patients with this disease.-Zeng, Y., Li, B., Liang, Y., Reeves, P. M., Qu, X., Ran, C., Liu, Q., Callahan, M. V., Sluder, A. E., Gelfand, J. A., Chen, H., Poznansky, M. C. Dual blockade of CXCL12-CXCR4 and PD-1-PD-L1 pathways prolongs survival of ovarian tumor-bearing mice by prevention of immunosuppression in the tumor microenvironment.