Increased CXCL12 Levels Research Articles

PDGFRα-positive cell-derived TIMP-1 modulates adaptive immune responses to influenza A viral infection.

TIMP-1 (tissue inhibitor of metalloproteinases-1) is a physiologic inhibitor of the matrix metalloproteinases (MMPs), but little is known about the role of TIMP-1 in regulating the pathogenesis of influenza A virus (IAV) infection. Here, we performed both in vivo and in vitro experiments to investigate the regulation and function of TIMP-1 during IAV infection. Specifically, plasma levels of TIMP-1 are significantly increased in human subjects and wild-type (WT) mice infected with 2009 H1N1 IAV compared with levels in uninfected controls. Also, TIMP-1 is strikingly upregulated in PDGFRα positive (PDGFRα+) cells in IAV-infected murine lungs as demonstrated using conditional KO (cKO) mice with a specific deletion of Timp-1 in PDGFRα+ cells. Our in vitro data indicated that TIMP-1 is induced by TGF-β during lipofibroblast (lipoFBs)-to-myofibroblast (myoFB) transdifferentiation. Timp-1 deficiency protects mice from H1N1 IAV-induced weight loss, mortality, and lung injury. IAV-infected Timp-1 deficient mice showed increased macrophages, and B and T cell counts in bronchoalveolar lavage (BAL) on day 7 post-infection (p.i.), but reduced BAL neutrophil counts. Increased Cxcl12 levels were detected in both BAL cells and lungs from Timp-1 deficient mice on day 3 p.i. Taken together, our data strongly link TIMP-1 to IAV pathogenesis. We identified that PDGFRα-lineage cells are the main cellular source of elevated TIMP-1 during IAV infection. Loss of Timp-1 attenuates IAV-induced mortality and promotes T and B cell recruitment. Thus, TIMP-1 may be a novel therapeutic target for IAV infection.

Increased CXCL12, a potential CSF biomarker for differential diagnosis of amyotrophic lateral sclerosis

Abstract Amyotrophic lateral sclerosis (ALS) is a debilitating and lethal neurodegenerative disorder marked by the gradual deterioration of motor neurons. Diagnosing ALS is challenging due to the lack of reliable diagnostic tools, with clinical assessment being the primary criterion. Recently, increased levels of neurofilament light chain (NF-L) in CSF have been considered a useful biomarker in disease, correlating with disease progression but not specific for diagnosis. This study utilized ELISA to measure CSF CXCL12 levels in healthy controls (HC), ALS patients, and patients with ALS-mimic disorders, assessing its potential as a diagnostic biomarker and comparing it with NF-L levels. Our results confirmed previous findings, showing increased CXCL12 levels in ALS patients compared to HC (797.07 ± 31.84 pg/mL vs. 316.15 ± 16.6 pg/mL; p=0.000) and increased CSF NF-L levels in ALS (4,565.63 ± 263.77 pg/mL) compared to HC (847.86 ± 214.37 pg/mL; p=0.000). Increased CXCL12 levels were specific to ALS, not seen in ALS-mimic conditions like myelopathies (252.20 ± 23.16 pg/mL; p=0.000), inflammatory polyneuropathies (IP) (270.24 ± 32.23 pg/mL; p=0.000), and other mimic diseases (OMD) (228.91 ± 29.20 pg/mL; p=0.000). In contrast, CSF NF-L levels in ALS overlapped with those in myelopathies (2,900.11 ± 872.20 pg/mL; p=0.821) and OMD (3,169.75 ± 1,096.65 pg/mL; p=0.63), but not with IP (1,156.4 ± 356.6 pg/mL; p=0.000). ROC curve analysis indicated significant differences between the AUC values of CXCL12 and NF-L in their diagnostic capacities. CXCL12 could differentiate between ALS and myelopathies (AUC: 0.99 ± 0.005), IP (AUC: 0.962 ± 0.027), and OMD (AUC: 1.00 ± 0.00), whereas NF-L was only effective in IP cases (AUC: 0.92 ± 0.048), not in myelopathies (AUC: 0.71 ± 0.09) or OMD (AUC: 0.69 ± 0.14). We also evaluated CXCL12 levels in plasma (ALS (2,022 ± 81.8 pg/mL) vs HC (1,739.43 ± 77.3 pg/mL; p=0.015)) but found CSF determination (AUC: 0.97 ± 0.012) to be more accurate than plasma determination (AUC: 0.65 ± 0.063). In plasma, SIMOA NF-L determination (ALS (86.00 ± 12.23 pg/mL) vs HC (12.69 ± 1.15 pg/mL); p=0.000) was more accurate than plasma CXCL12 (AUC: 0.98 ± 0.01405). These findings suggest that CSF CXCL12 levels can enhance diagnostic specificity in distinguishing ALS from ALS-mimic disorders, compared to NF-L. Larger studies are needed to validate these results, but CXCL12 determination shows promising diagnostic potential.

1647-P: Novel Functions of CXCL12 as a Brown Adipocyte–Derived Secreted Factor

The capacity of brown adipose tissue (BAT) to regulate metabolism through cold-induced thermogenesis and secretion of molecules appeals as a potential therapeutic against metabolic disease. BAT secreted factors have gained interest as they may coordinate the adaptive response to cold and tissue remodeling. Yet, BAT secretory functions need deeper investigation before identifying druggable candidates. Thus, our group aimed to study secreted factors from active brown adipocytes that may sway adipocyte function and/or may orchestrate inter-cellular communications. For this, mRNA levels in mature adipocytes of brown, beige and white adipose depots from mice exposed to 21 days of cold were evaluated using RNA sequencing, and bioinformatic analysis was used to filter for potentially secreted factors. Cxcl12 was found to be the most cold-induced chemokine specifically in BAT. mRNA expression analysis of Cxcl12 by qPCR and fluorescence in-situ hybridization revealed its enrichment in brown adipocytes upon cold. Cold also increased CXCL12 levels in BAT media but not plasma, indicating a potential local action. Cxcl12 knockdown in active brown adipocytes impaired thermogenesis, estimated by Ucp1 gene expression, norepinephrine-induced lipolysis and mitochondrial respiration, despite intact β-adrenergic signaling, as estimated by immunoblotting of phosphorylated proteins. Together, these data suggest that Cxcl12 regulates adipocyte function independently from the β-adrenergic pathway. Additionally, CXCL12 exerted inter-cellular crosstalks by promoting macrophage chemotaxis and neurite outgrowth in vitro. Here we present CXCL12 as a novel brown adipocyte, cold-induced secreted factor involved in adipocyte function and inter-cellular crosstalk within BAT. Further characterization of the role of CXCL12 and other secreted factors in BAT will provide valuable knowledge on the adaptive mechanisms of BAT to cold and may open new avenues to leverage BAT functions for the treatment of metabolic disease. Disclosure M.Agueda oyarzabal: None. M.Tozzi: None. T.W.Schwartz: None. C.C.Schéele: Research Support; Novo Nordisk A/S. B.Emanuelli: None. K.Plucinska: None. M.Isidor: None. L.R.Ingerslev: None. P.Petersen: None. O.Dmytriyeva: None. J.Henningsen: None. E.Brown: None. K.Rupar: None. Funding Novo Nordisk Foundation (18CC0034900, 19SA0035436); Copenhagen Bioscience PhD Program

The Diagnostic and prognostic value of CXCL12 (SDF-1α) level in Mycobacterium tuberculosis infection and disease.

New diagnostic tools are being investigated for rapid and accurate TB detection. We aimed to find out the diagnostic yield and accuracy of chemokine CXCL12 (SDF-1a) levels in diagnosing active TB (aTB) and making a differential diagnosis from other several infectious/non-infectious pulmonary conditions. We collected demographic, clinic features and studied plasma CXCL12 levels using ELISA kit of the participants, classified into five categories: aTB (n = 30); cured TB (cTB, n = 15); close contacts of aTB (CC, n = 15); chronic obstructive pulmonary disease (COPD) with active nonspecific pulmonary infection (infCOPD, n = 15); and healthy controls (HC, n = 15). CXCL12 levels were highest in aTB, but no significant difference was seen between other groups. When a cut-off level for CXCL12 was determined as 2835 pg/mL, the increased CXCL12 rate was significantly more in aTB than CC and HC (p = 0.02, p = 0.05). Also, participants with an active infection (aTB and infCOPD) had significantly higher increased CXCL12 rates (p = 0.01). The sensitivity and specificity of CXCL12 for diagnosing aTB were found to be 0.56 and 0.63, respectively. We found that bacterial load, the radiological severity and the extent of chest x-ray involvement were independent factors for increased CXCL12 levels. Our study demonstrates that CXCL12 may be a representative of active pulmonary infection regardless of the cause but correlated with the severity of the disease; enabling this test to be used as a prognostic factor rather than a diagnostic test for aTB.

Increased C-X-C Motif Chemokine Ligand 12 Levels in Cerebrospinal Fluid as a Candidate Biomarker in Sporadic Amyotrophic Lateral Sclerosis.

Sporadic amyotrophic lateral sclerosis (sALS) is a fatal progressive neurodegenerative disease affecting upper and lower motor neurons. Biomarkers are useful to facilitate the diagnosis and/or prognosis of patients and to reveal possible mechanistic clues about the disease. This study aimed to identify and validate selected putative biomarkers in the cerebrospinal fluid (CSF) of sALS patients at early disease stages compared with age-matched controls and with other neurodegenerative diseases including Alzheimer disease (AD), spinal muscular atrophy type III (SMA), frontotemporal dementia behavioral variant (FTD), and multiple sclerosis (MS). SWATH acquisition on liquid chromatography-tandem mass spectrometry (LC–MS/MS) for protein quantitation, and ELISA for validation, were used in CSF samples of sALS cases at early stages of the disease. Analysis of mRNA and protein expression was carried out in the anterior horn of the lumbar spinal cord in post-mortem tissue of sALS cases (terminal stage) and controls using RTq-PCR, and Western blotting, and immunohistochemistry, respectively. SWATH acquisition on liquid chromatography-tandem mass spectrometry (LC–MS/MS) revealed 51 differentially expressed proteins in the CSF in sALS. Receiver operating characteristic (ROC) curves showed CXCL12 to be the most valuable candidate biomarker. We validated the values of CXCL12 in CSF with ELISA in two different cohorts. Besides sALS, increased CXCL12 levels were found in MS but were not altered in AD, SMA, and FTD. Therefore, increased CXCL12 levels in the CSF can be useful in the diagnoses of MS and sALS in the context of the clinical settings. CXCL12 immunoreactivity was localized in motor neurons in control and sALS, and in a few glial cells in sALS at the terminal stage; CXCR4 was in a subset of oligodendroglial-like cells and axonal ballooning of motor neurons in sALS; and CXCR7 in motor neurons in control and sALS, and reactive astrocytes in the pyramidal tracts in terminal sALS. CXCL12/CXCR4/CXCR7 axis in the spinal cord probably plays a complex role in inflammation, oligodendroglial and astrocyte signaling, and neuronal and axonal preservation in sALS.

Islet Harvest in Carbon Monoxide-Saturated Medium for Chronic Pancreatitis Patients Undergoing Islet Autotransplantation

Stresses encountered during human islet isolation lead to unavoidable β-cell death after transplantation. This reduces the chance of insulin independence in chronic pancreatitis patients undergoing total pancreatectomy and islet autotransplantation. We tested whether harvesting islets in carbon monoxide-saturated solutions is safe and can enhance islet survival and insulin independence after total pancreatectomy and islet autotransplantation. Chronic pancreatitis patients who consented to the study were randomized into carbon monoxide (islets harvested in a carbon monoxide-saturated medium) or control (islets harvested in a normal medium) groups. Islet yield, viability, oxygen consumption rate, β-cell death (measured by unmethylated insulin DNA), and serum cytokine levels were measured during the peri-transplantation period. Adverse events, metabolic phenotypes, and islet function were measured prior and at 6 months post-transplantation. No adverse events directly related to the infusion of carbon monoxide islets were observed. Carbon monoxide islets showed significantly higher viability before transplantation. Subjects receiving carbon monoxide islets had less β-cell death, decreased CCL23, and increased CXCL12 levels at 1 or 3 days post transplantation compared with controls. Three in 10 (30%) of the carbon monoxide subjects and none of the control subjects were insulin independent. This pilot trial showed for the first time that harvesting human islets in carbon monoxide-saturated solutions is safe for total pancreatectomy and islet autotransplantation patients.

Epigenetic upregulation of hippocampal CXCL12 contributes to context spatial memory-associated morphine conditioning

Conditioned place preference (CPP) is a learned behavior, in which animals learn to associate environmental contexts with rewarding effects. The formation of CPP is an integrated outcome of multiple learning processes. Although multiple anatomical substrates underlying this contextual learning have been proposed, it remains unknown whether a specific molecular signaling pathway within CA1 mediates context learning associated with morphine conditioning. Here, we showed that repeated context learning associated with morphine conditioning significantly increased CXCL12 levels in hippocampal CA1 neurons, and the inhibition of CXCL12 expression ameliorated the CPP behavior following context exposure with morphine conditioning. Additionally, repeated context exposure with morphine conditioning increased the phosphorylation of STAT3 and the acetylation of histone H4 in CXCL12-expressing neurons in CA1. Immunoprecipitation and chromatin immunoprecipitation assays demonstrated that repeated context exposure with morphine conditioning increased the binding of STAT3 to the CXCL12 gene promoter and the interaction between STAT3 and p300, which contributed to the enhanced transcription of CXCL12 by increasing the acetylation of histone H4 in the CXCL12 gene promoter. The inhibition of STAT3 by intrathecal injection of S3I-201 suppressed the acetylation of histone H4. These data demonstrated the epigenetic upregulation of CXCL12 following repeated context exposure with morphine conditioning, which potentially contributed to the spatial memory consolidation associated with conditioned place preference induced by morphine conditioning.

Local Irradiation Induces Systemic Inflammatory Response and Alteration of the Hematopoietic Stem Cell Niche

Radiotherapy is used in the treatment of ~50% of tumors. We and others have reported long-term suppression of hematopoietic stem and progenitor cells (HSPCs) in the setting of total body irradiation; however, it has been shown that even relatively small irradiation volumes can result in systemic adverse events, such as myeloablation and secondary malignancies. The mechanisms underlying these effects are unclear. We hypothesize that localized radiation may activate a systemic inflammatory response that can acutely alter HSPCs and bone marrow microenvironment (BMME) components, including marrow stromal cells (MSCs), thereby contributing to late effects. We therefore established a murine model of targeted irradiation (TR) using a small animal radiation research platform (SARRP). Methods: We administered local irradiation to a single tibia of 6-8 week old C57BL/6 male mice using a single dose of 15 Gy. Subsequently, we analyzed peripheral blood, BM, BM extracellular fluid (BMEF), collagenase-1 digested bone associated cells of both the irradiated (TR) and non-irradiated, contralateral (CONT) tibiae at 2, 6, 48 hours, 1 and 3 weeks post-TR, performing phenotypic (flow cytometry) and cytokine analyses. For all studies, n = 10-13 mice/time point. Results: In the TR tibia at 2 hours, although total cell numbers were unchanged, there was a significant upregulation of inflammatory cytokines (interleukin 1β (IL1b), IL18), chemokines (CXCL2, CXCL10, CCL2, CCL3) and macrophage colony stimulating factor (M-CSF). Of note, most of these changes normalized by 48 hours (M-CSF at 1 week). Changes in mediator expression were followed, at 6 hours post-TR, by significant increases in macrophage (macs) numbers, including CD206 phagocytic macs, neutrophils (PMNs) and cytotoxic lymphocytes, including CD8+ cells expressing CXCR3+, the receptor for CXCL9 and CXCL10. Interestingly, similar to the TR tibia, CXCL2 expression was also increased significantly in the CONT at 2 hours, followed (6 hours) by significant increases in macs and CD8+ cells, suggesting a systemic or abscopal effect. With respect to the effects of radiation on HSPCs, by 6 hours, most of the stem and progenitor cell (HSPC) populations in the TR marrow were significantly decreased; the decrease in long-term-HSCs was delayed until 48 hours post-TR. All populations remained severely depleted until 3 weeks post RT, demonstrating a rapid and sustained effect of TR on all HSPCs within the irradiation volume. In comparison, in the CONT tibia at 6 hours, CD41+ HSCs were expanded; this is consistent with previous demonstrations that CD41+ LT-HSCs expand with inflammatory signals and suggests that TR-induced signals induced a systemic impact on the non-irradiated HSPCs. By 1 week post-radiation, short term-HSCs were significantly decreased in the CONT marrow, likely due to mobilization since CFU-Cs were correspondingly significantly increased in the circulation. Finally, MSCs, previously shown to support HSCs, were found to be significantly increased in the TR tibia starting at 6 hours and peaking at 48 hours post-radiation. Surprisingly, MSCs were also expanded in the CONT marrow at 48 hours; this expansion was likely associated with the increased CXCL12 levels seen in both TR and CONT marrow, although the CXCL12 levels were higher in the irradiated tibia. Taken together, these changes indicate TR-induced global disruption of the HSC niche. Furthermore, in addition to the transient effects of localized irradiation, we observed a second wave of inflammatory signals, including a significant increase in CCL3, at 1 week post-TR and increased IL1b in the CONT marrow at 3 weeks, changes that may have contributed to the sustained loss of HSPC populations. Conclusions: We present the effects of local irradiation on global hematopoiesis, showing that, in addition to the anticipated acute local changes in the irradiated bone marrow, TR-induced persistent and, more importantly, systemic inflammation. We believe that using this murine model will allow us to dissect the contribution of direct (local) and indirect (systemic) responses to radiation on treatment effects, such as marrow failure and secondary malignancies. Disclosures No relevant conflicts of interest to declare.

Expression and secretion of CXCL12 are enhanced in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD), one of the most common human monogenic diseases (frequency of 1/1000-1/400), is characterized by numerous fluid-filled renal cysts (RCs). Inactivation of the PKD1 or PKD2 gene by germline and somatic mutations is necessary for cyst formation in ADPKD. To mechanistically understand cyst formation and growth, we isolated RCs from Korean patients with ADPKD and immortalized them with human telomerase reverse transcriptase (hTERT). Three hTERT-immortalized RC cell lines were characterized as proximal epithelial cells with germline and somatic PKD1 mutations. Thus, we first established hTERT-immortalized proximal cyst cells with somatic PKD1 mutations. Through transcriptome sequencing and Gene Ontology (GO) analysis, we found that upregulated genes were related to cell division and that downregulated genes were related to cell differentiation. We wondered whether the upregulated gene for the chemokine CXCL12 is related to the mTOR signaling pathway in cyst growth in ADPKD. CXCL12 mRNA expression and secretion were increased in RC cell lines. We then examined CXCL12 levels in RC fluids from patients with ADPKD and found increased CXCL12 levels. The CXCL12 receptor CXC chemokine receptor 4 (CXCR4) was upregulated, and the mTOR signaling pathway, which is downstream of the CXCL12/CXCR4 axis, was activated in ADPKD kidney tissue. To confirm activation of the mTOR signaling pathway by CXCL12 via CXCR4, we treated the RC cell lines with recombinant CXCL12 and the CXCR4 antagonist AMD3100; CXCL12 induced the mTOR signaling pathway, but the CXCR4 antagonist AMD3100 blocked the mTOR signaling pathway. Taken together, these results suggest that enhanced CXCL12 in RC fluids activates the mTOR signaling pathway via CXCR4 in ADPKD cyst growth.

Abstract B206: Evaluation of tumor biomarkers in patients with microsatellite-stable, metastatic colorectal or pancreatic cancer treated with the CXCL12 inhibitor NOX-A12 and preliminary safety in combination with PD-1 checkpoint inhibitor pembrolizumab

Abstract Background: NOX-A12 (olaptesed pegol) is a novel inhibitor of the chemokine CXCL12, ligand for CXCR4 and CXCR7, for treatment of solid tumors. Binding of the CXCL12 ligand by NOX-A12 prevents receptor engagement and also blocks the ability of CXCL12 to create a chemotactic concentration gradient by neutralization of the anchor domain. CXCL12 in complex with NOX-A12 has an increased half-life relative to unbound CXCL12, and as such increased CXCL12 levels are a marker of inhibition. The OPERA study (NCT03168139) is a phase 1/2 open-label clinical study to evaluate pharmacodynamic effects and safety of monotherapy with NOX-A12 and safety and efficacy of a combination of NOX-A12 with pembrolizumab in advanced MSS, metastatic colorectal and pancreatic cancer with liver metastasis. The study comprises two weeks of NOX-A12 monotherapy followed by repeated 21-day cycles of NOX-A12 plus pembrolizumab. Here we present pharmacodynamic biomarker data from for monotherapy phase with NOX-A12 as well as safety for the combination with pembrolizumab. Methods: Patients received 300 mg NOX-A12 by i.v. infusion on days 1, 4, 8, and 11 of the monotherapy phase. Needle biopsies were taken from suitable liver metastases before treatment and on day 14, peripheral blood was drawn at the same time points. Collected tumor samples were assessed for immune cell infiltration by IHC and cytokine signature using multiplex protein analysis. Results: At the time of abstract submission, 19 out of 20 patients have been recruited, 10 with colorectal and 9 with pancreatic cancer. Serial biopsies at baseline and end of monotherapy suitable for immunohistochemistry (IHC) and cytokine analysis were obtained from 12 out of 19 patients. CXCL12 levels were found to be increased in blood, but also in post-treatment tumor biopsies, suggesting penetration of NOX-A12 into the tumor. The comparison of cytokine levels in the currently available baseline tumor biopsies with those taken after two weeks of NOX-A12 monotherapy revealed changes in markers that are consistent with a Th1-like immune response in multiple patients. In particular IFN-γ, IL-2 and TNF-β were increased, accompanied by an increase of CXCL9 and/or CXCL10 indicating simultaneous T-cell attraction, which indicates a tissue response to treatment with NOX-A12. However, there were also increased levels of IL-1α, IL-1β and IL-6 in a number of patients, indicating potential myeloid counter regulation. IHC analysis is ongoing, and results for all patients will be presented. Treatment with NOX-A12 monotherapy and in combination with pembrolizumab was generally safe and well tolerated (139 AEs in total, thereof 45% grade 1; 37% grade 2; 17% grade 3; no grade 4 and 1 % grade 5). Conclusions: NOX-A12 penetrates into the tumor where it binds and neutralizes CXCL12. Changes in the cytokine signature suggest that NOX-A12 modulates the tumor microenvironment and induces an immune-stimulatory Th1-like signature in multiple patients. The safety profile of NOX-A12 combined with pembrolizumab is consistent with that of pembrolizumab in advanced cancer patients. Citation Format: Niels Halama, Ulrike Prüfer, Anna Froemming, Diana Beyer, Dirk Eulberg, Jarl Ulf Jungnelius, Aram Mangasarian. Evaluation of tumor biomarkers in patients with microsatellite-stable, metastatic colorectal or pancreatic cancer treated with the CXCL12 inhibitor NOX-A12 and preliminary safety in combination with PD-1 checkpoint inhibitor pembrolizumab [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr B206.

SMAD signaling regulates CXCL12 expression in the bone marrow niche, affecting homing and mobilization of hematopoietic progenitors.

We recently demonstrated that ex vivo activation of SMAD-independent bone morphogenetic protein 4 (BMP4) signaling in hematopoietic stem/progenitor cells (HSPCs) influences their homing into the bone marrow (BM). Here, we assessed whether alterations in BMP signaling in vivo affects adult hematopoiesis by affecting the BM niche. We demonstrate that systemic inhibition of SMAD-dependent BMP signaling by infusion of the BMP antagonist noggin (NGN) significantly increased CXCL12 levels in BM plasma leading to enhanced homing and engraftment of transplanted HSPCs. Conversely, the infusion of BMP7 but not BMP4, resulted in decreased HSPC homing. Using ST2 cells as an in vitro model of BM niche, we found that incubation with neutralizing anti-BMP4 antibodies, NGN, or dorsomorphin (DM) as well as knockdown of Smad1/5 and Bmp4, all enhanced CXCL12 production. Chromatin immunoprecipitation identified the SMAD-binding element in the CXCL12 promoter to which SMAD4 binds. When deleted, increased CXCL12 promoter activity was observed, and NGN or DM no longer affected Cxcl12 expression. Interestingly, BMP7 infusion resulted in mobilization of only short-term HSCs, likely because BMP7 affected CXCL12 expression only in osteoblasts but not in other niche components. Hence, we describe SMAD-dependent BMP signaling as a novel regulator of CXCL12 production in the BM niche, influencing HSPC homing, engraftment, and mobilization.

Pulmonary Mastocytosis and Enhanced Lung Inflammation in Mice Heterozygous Null for the Foxf1 Gene

The Forkhead Box f1 (Foxf1) transcriptional factor (previously known as HFH-8 or Freac-1) is expressed in endothelial and smooth muscle cells in the embryonic and adult lung. To assess effects of Foxf1 during lung injury, we used CCl(4) and butylated hydroxytoluene (BHT) injury models. Foxf1(+/-) mice developed severe airway obstruction and bronchial edema, associated with increased numbers of pulmonary mast cells and increased mast cell degranulation after injury. Pulmonary inflammation in Foxf1(+/-) mice was associated with diminished expression of Foxf1, increased mast cell tryptase, and increased expression of CXCL12, the latter being essential for mast cell migration and chemotaxis. After ovalbumin (OVA) sensitization and OVA challenge, increased lung inflammation, airway hyperresponsiveness to methacholine, and elevated expression of CXCL12 were observed in Foxf1(+/-) mice. During lung development, Foxf1(+/-) embryos displayed a marked increase in pulmonary mast cells before birth, and this was associated with increased CXCL12 levels in the lung. Expression of a doxycycline-inducible Foxf1 dominant-negative transgene in primary cultures of lung endothelial cells increased CXCL12 expression in vitro. Foxf1 haploinsufficiency caused pulmonary mastocytosis and enhanced pulmonary inflammation after chemically induced or allergen-mediated lung injury, indicating an important role for Foxf1 in the pathogenesis of pulmonary inflammatory responses.