Exploration of MELK as a downstream of Del-1 and druggable targets in triple-negative breast cancer.

PURPOSE: In our previous study, Developmental endothelial locus-1 (Del-1) was a promising predictive marker for breast cancer. However, the downstream targets of Del-1 remain unknown. Here, we sought to discover a druggable target downstream of Del-1 and investigate the mechanism by which it regulates the course of breast cancer. METHODS: To investigate Del-1 downregulation effect on breast cancer, we performed transcriptome analysis using RNA sequencing of Del-1 knockdowned MDA-MB-231 cell line Plus, to investigate the expression of Del-1 and Maternal embryonic leucine zipper kinase (MELK), mRNA levels in eight different triple-Negative Breast Cancer (TNBC) cell lines were analyzed. High-throughput sequencing was performed on total RNA isolated. OTS167 was used for MELK inhibition. The effects of MELK on cell proliferation and invasion were determined using the MTT and Matrigel transwell assays. Furthermore, we examined MELK expression in breast cancer tissue. RESULTS: Del-1 and MELK mRNA expression levels were significantly higher in the TNBC cell lines, MDA-MB-468, HCC-1806, and MBA-MB-231. Knocking down Del-1 with siRNA in HCC-1806 and MBA-MB-231 cells significantly decreased MELK expression and thus suggested a possible relationship between Del-1 and MELK. In MDA-MB-468 cells, a basal-like 1 TNBC cell line, OTS167 significantly inhibited breast cancer cell proliferation and promoted cell apoptosis. To further investigate the relationship between Del-1 and MELK, dual inhibition of both Del-1 and MELK was performed, which significantly reduced the viability of MDA-MB-468 and MBA-MB-231 cells. CONCLUSION: We found that MELK acts downstream of Del-1 and is a promising druggable target, especially in basal-like and mesenchymal stem-like subtype.

DEL-1: a promising treatment for AMD-associated ER stress in retinal pigment epithelial cells.

BACKGROUND: Age-related macular degeneration (AMD) is an irreversible eye disease that can cause blurred vision. Regular exercise has been suggested as a therapeutic strategy for treating AMD, but how exercise improves AMD is not yet understood. This study investigated the protective effects of developmental endothelial locus-1 (DEL-1), a myokine upregulated during exercise, on endoplasmic reticulum (ER) stress-induced injury in retinal pigment epithelial cells. METHODS: We evaluated the levels of AMPK phosphorylation, autophagy markers, and ER stress markers in DEL-1-treated human retinal pigment epithelial cells (hRPE) using Western blotting. We also performed cell viability, caspase 3 activity assays, and autophagosome staining. RESULTS: Our findings showed that treatment with recombinant DEL-1 dose-dependently reduced the impairment of cell viability and caspase 3 activity in tunicamycin-treated hRPE cells. DEL-1 treatment also alleviated tunicamycin-induced ER stress markers and VEGF expression. Moreover, AMPK phosphorylation and autophagy markers were increased in hRPE cells in the presence of DEL-1. However, the effects of DEL-1 on ER stress, VEGF expression, and apoptosis in tunicamycin-treated hRPE cells were reduced by AMPK siRNA or 3-methyladenine (3-MA), an autophagy inhibitor. CONCLUSIONS: Our study suggests that DEL-1, a myokine, may have potential as a treatment strategy for AMD by attenuating ER stress-induced injury in retinal pigment epithelial cells.

Del-1 Plays a Protective Role against COPD Development by Inhibiting Inflammation and Apoptosis.

Neutrophilic inflammation is a prominent feature of chronic obstructive pulmonary disease (COPD). Developmental endothelial locus-1 (Del-1) has been reported to limit excessive neutrophilic inflammation by inhibiting neutrophil adhesion to the vascular endothelial cells. However, the effects of Del-1 in COPD are not known. We investigated the role of Del-1 in the pathogenesis of COPD. Del-1 protein expression was decreased in the lungs of COPD patients, especially in epithelial cells and alveolar macrophages. In contrast to human lung tissue, Del-1 expression was upregulated in lung tissue from mice treated with cigarette smoke extracts (CSE). Overexpression of Del-1 significantly suppressed IL-8 release and apoptosis in CSE-treated epithelial cells. In contrast, knockdown of Del-1 enhanced IL-8 release and apoptosis. In macrophages, overexpression of Del-1 significantly suppressed inflammatory cytokine release, and knockdown of Del-1 enhanced it. This anti-inflammatory effect was mediated by inhibiting the phosphorylation and acetylation of NF-κB p65. Nuclear factor erythroid 2-related factor 2 (Nrf2) activators, such as quercetin, resveratrol, and sulforaphane, increased Del-1 in both cell types. These results suggest that Del-1, mediated by Nrf2, plays a protective role against the pathogenesis of COPD, at least in part through anti-inflammatory and anti-apoptotic effects.

Concomitant deletion of the short arm (del(1p13.3)) and amplification or gain (1q21) of chromosome 1 by fluorescence in situ hybridization are associated with a poor clinical outcome in multiple myeloma.

BACKGROUND: Chromosome 1 abnormalities in multiple myeloma (MM) are increasingly recognized as high risk-defining features. The authors report the prognostic value of del(1p13.3) by fluorescence in situ hybridization (FISH) at enrollment in subjects treated on total therapy clinical trials 2-6. METHODS: FISH probes were generated from specific BAC DNA clones for the AHCYL1 gene locus (1p13.3) and the CKS1B locus (1q21). RESULTS: A total of 1133 patients were included in this analysis. Although del(1p13.3) was detected in 220 (19.4%) patients, 1q21gain or 1q21amp were observed in 300 (26.5%) and 150 (13.2%) patients, respectively. Concomitant del(1p13.3) with 1q21 gain or amp was observed in 65 (5.7%) and 29 (2.5%) patients, respectively. There was enrichment of high-risk features such as International Staging System (ISS) stage 3 disease and gene expression profiling (GEP)70 high risk (HR) in the group with del(1p13.3). Presence of del(1p13.3) confers inferior progression-free survival (PFS) and overall survival (OS). On multivariate analysis, the presence of ISS stage 3 disease, GEP70 HR, 1q21gain, and 1q21amp were independent predictors of PFS or OS. CONCLUSIONS: The PFS and OS of patients with combined abnormalities of del (1p13.3)/1q21gain or amp was significantly worse compared to del(1p13.3) alone and 1q21gain or 1q21 amp alone, which identifies a subset of patients with poor clinical outcomes.

DEL-1, as an anti-neutrophil transepithelial migration molecule, inhibits airway neutrophilic inflammation in asthma.

BACKGROUND: Neutrophil migration into the airways is a key process in neutrophilic asthma. Developmental endothelial locus-1 (DEL-1), an extracellular matrix protein, is a neutrophil adhesion inhibitor that attenuates neutrophilic inflammation. METHODS: Levels of DEL-1 were measured in exhaled breath condensate (EBC) and serum in asthma patients by ELISA. DEL-1 modulation of neutrophil adhesion and transepithelial migration was examined in a co-culture model in vitro. The effects of DEL-1-adenoviral vector-mediated overexpression on ovalbumin/lipopolysaccharide (OVA/LPS)-induced neutrophilic asthma were studied in mice in vivo. RESULTS: DEL-1 was primarily expressed in human bronchial epithelial cells and was decreased in asthma patients. Serum DEL-1 concentrations were reduced in patients with severe asthma compared with normal subjects (567.1 ± 75.3 vs. 276.8 ± 29.36 pg/mL, p < .001) and were negatively correlated to blood neutrophils (r = -0.2881, p = .0384) and neutrophil-to-lymphocyte ratio (NLR) (r = -0.5469, p < .0001). DEL-1 concentrations in the EBC of severe asthmatic patients (113.2 ± 8.09 pg/mL) were also lower than normal subjects (193.0 ± 7.61 pg/mL, p < .001) and were positively correlated with the asthma control test (ACT) score (r = 0.3678, p = .0035) and negatively related to EBC IL-17 (r = -0.3756, p = .0131), myeloperoxidase (MPO) (r = -0.5967, p = .0055), and neutrophil elastase (NE) (r = -0.5488, p = .0009) expression in asthma patients. Neutrophil adhesion and transepithelial migration in asthma patients were associated with LFA-1 binding to ICAM-1 and inhibited by DEL-1. DEL-1 mRNA and protein expression in human bronchial epithelial cells were regulated by IL-17. Exogenous DEL-1 inhibited IL-17-enhanced neutrophil adhesion and migration. DEL-1 expression was decreased while neutrophil infiltration was increased in the airway of a murine model of neutrophilic asthma. This was prevented by DEL-1 overexpression. CONCLUSIONS: DEL-1 down-regulation leads to increased neutrophil migration across bronchial epithelial cells and is associated with neutrophilic airway inflammation in asthma.

Decreased Levels of Soluble Developmental Endothelial Locus-1 Are Associated with Thrombotic Microangiopathy in Pregnancy.

HELLP (Hemolysis, Elevated Liver enzymes and Low Platelets) syndrome is a life-threatening complication of pregnancy, which is often secondary to preeclampsia. To date, there is no biomarker in clinical use for the early stratification of women with preeclampsia who are under increased risk of HELLP syndrome. Herein, we show that the levels of circulating developmental endothelial locus-1 (DEL-1), which is an extracellular immunomodulatory protein, are decreased in patients with HELLP syndrome compared to preeclampsia. DEL-1 levels are also negatively correlated with the circulating levels of kidney injury molecule-1 (KIM-1), which is a biomarker for disorders associated with kidney damage. Receiver-operating characteristic curve analysis for DEL-1 levels and the DEL-1 to KIM-1 ratio demonstrates that these values could be used as a potential biomarker that distinguishes patients with HELLP syndrome and preeclampsia. Finally, we show that placental endothelial cells are a source for DEL-1, and that the expression of this protein in placenta from patients with HELLP syndrome is minimal. Taken together, this study shows that DEL-1 is downregulated in HELLP syndrome both in the circulation and at the affected placental tissue, suggesting a potential role for this protein as a biomarker, which must be further evaluated.

The secreted protein DEL-1 activates a ß3 integrin-FAK-ERK1/2-RUNX2 pathway and promotes osteogenic differentiation and bone regeneration.

The integrin-binding secreted protein developmental endothelial locus-1 (DEL-1) is involved in the regulation of both the initiation and resolution of inflammation in different diseases, including periodontitis, an oral disorder characterized by inflammatory bone loss. Here, using a mouse model of bone regeneration and in vitro cell-based mechanistic studies, we investigated whether and how DEL-1 can promote alveolar bone regeneration during resolution of experimental periodontitis. Compared with WT mice, mice lacking DEL-1 or expressing a DEL-1 variant with an Asp-to-Glu substitution in the RGD motif ("RGE point mutant"), which does not interact with RGD-dependent integrins, exhibited defective bone regeneration. Local administration of DEL-1 or of its N-terminal segment containing the integrin-binding RGD motif, but not of the RGE point mutant, reversed the defective bone regeneration in the DEL-1-deficient mice. Moreover, DEL-1 (but not the RGE point mutant) promoted osteogenic differentiation of MC3T3-E1 osteoprogenitor cells or of primary calvarial osteoblastic cells in a ß3 integrin-dependent manner. The ability of DEL-1 to promote in vitro osteogenesis, indicated by induction of osteogenic genes such as the master transcription factor Runt-related transcription factor-2 (Runx2) and by mineralized nodule formation, depended on its capacity to induce the phosphorylation of focal adhesion kinase (FAK) and of extracellular signal-regulated kinase 1/2 (ERK1/2). We conclude that DEL-1 can activate a ß3 integrin-FAK-ERK1/2-RUNX2 pathway in osteoprogenitors and promote new bone formation in mice. These findings suggest that DEL-1 may be therapeutically exploited to restore bone lost due to periodontitis and perhaps other osteolytic conditions.

Regulatory role of local tissue signal Del-1 in cancer and inflammation: a review.

Developmental endothelial locus-1 (Del-1) is a secretory, multifunctional domain protein. It can bind to integrins and phosphatidylserine. As a local tissue signal, it plays a regulatory role in the cancer microenvironment and inflammation. Del-1 has destructive effects in most cancers and is associated with the progression and invasion of some cancers. In contrast, Del-1 also plays a protective role in inflammation. Del-1 regulates inflammation by regulating the generation of neutrophils in bone marrow, inhibiting the recruitment and migration of neutrophils and accelerating the clearance of neutrophils by macrophages. Del-1 and IL-17 are reciprocally regulated, and their balance maintains immune system homeostasis. Del-1 is expected to become a new therapeutic target for inflammatory disorders such as multiple sclerosis.

Immune and regulatory functions of neutrophils in inflammatory bone loss.

Although historically viewed as merely anti-microbial effectors in acute infection or injury, neutrophils are now appreciated to be functionally versatile with critical roles also in chronic inflammation. Periodontitis, a chronic inflammatory disease that destroys the tooth-supporting gums and bone, is particularly affected by alterations in neutrophil numbers or function, as revealed by observations in monogenic disorders and relevant mouse models. Besides being a significant debilitating disease and health burden in its own right, periodontitis is thus an attractive model to dissect uncharted neutrophil-associated (patho)physiological pathways. Here, we summarize recent evidence that neutrophils can contribute to inflammatory bone loss not only through the typical bystander injury dogma but intriguingly also through their absence from the affected tissue, where they normally perform important immunomodulatory functions. Moreover, we discuss recent advances in the interactions of neutrophils with the vascular endothelium and - upon extravasation - with bacteria, and how the dysregulation of these interactions leads to inflammatory tissue damage. Overall, neutrophils have both protective and destructive roles in periodontitis, as they are involved in both the maintenance of periodontal tissue homeostasis and the induction of inflammatory bone loss. This highlights the importance of developing approaches that promote or sustain a fine balance between homeostatic immunity and inflammatory pathology.

Overcoming Tamoxifen Resistance by Regulation of Del-1 in Breast Cancer.

BACKGROUND: Hormone receptor-positive breast cancer accounts for nearly two-thirds of breast cancer cases; it ultimately acquires resistance during endocrine treatment and becomes more aggressive. This study evaluated the role of developmental endothelial locus (Del)-1 in tamoxifen-resistant (TAM-R) breast cancer. METHODS: Del-1 expression in recurrent TAM-R breast cancer tissue was evaluated and compared to that in the original tumor tissue from the same patients. Del-1 expression was also evaluated in TAM-R cells by quantitative real-time PCR, western blotting, and enzyme-linked immunosorbent assay. The effects of Del-1 knockdown on the proliferation, migration, and invasion of TAM-R cells was assessed with wound-healing and Matrigel transwell assays. RESULTS: Del-1 was more highly expressed in recurrent breast cancer as compared to the original tumor tissues before initiation of endocrine treatment. Del-1 mRNA was upregulated in TAM-R and small interfering RNA-mediated knockdown of Del-1 suppressed the migration and proliferation of TAM-R cells while partly restoring TAM sensitivity. And the TAM resistance was recovered by knockdown of Del-1. CONCLUSIONS: TAM-R breast cancer is characterized by Del-1 overexpression and tumor progression can be inhibited by Del-1 depletion, which restores TAM sensitivity. Thus, therapeutic strategies that target Del-1 may be effective for the treatment of hormone-resistant breast cancer.

MicroRNA-137 Inhibits Cancer Progression by Targeting Del-1 in Triple-Negative Breast Cancer Cells.

MicroRNAs (miRNAs) can be used to target a variety of human malignancy by targeting their oncogenes or tumor suppressor genes. The developmental endothelial locus-1 (Del-1) might be under miRNA regulation. This study investigated microRNA-137 (miR-137) function and Del-1 expression in triple-negative breast cancer (TNBC) cells and tissues. Del-1 mRNA and miRNA-137 levels were determined via qRT-PCR in breast cancer cells (MDA-MB-231, MCF7, SK-BR3, and T-47D) and tissues from 30 patients with TNBC. The effects of miR-137 on cell proliferation, migration, and invasion were determined using MTT assays, wound healing, and Matrigel transwell assays. The luciferase reporter assay revealed direct binding of miR-137 to the 3'-UTR of Del-1. miR-137 inhibited cell proliferation, migration, and invasion of MDA-MB-231 cells. Among the 30 TNBC specimens, miR-137 was downregulated and Del-1 level in plasma was significantly elevated relative to normal controls. It is concluded that miR-137 regulates Del-1 expression in TNBC by directly binding to the Del-1 gene and cancer progression. The results implicate miR-137 as a new therapeutic biomarker for patients with TNBC.

Developmental endothelial locus-1 prevents development of peritoneal adhesions in mice.

Postoperative peritoneal adhesions, fibrous bands formed in the peritoneal cavity following surgery, represent a common, challenging and costly problem faced by surgeons and patients, for which effective therapeutic options are lacking. Since aberrant inflammation is one of the key mechanisms underlying peritoneal adhesion formation, here we set out to study the role of developmental endothelial locus-1 (Del-1), which has been recently identified as an endogenous inhibitor of inflammation, in the formation of postoperative peritoneal adhesions using a mouse model of peritoneal adhesions induced by ischemic buttons. Del-1-deficient mice had a higher incidence of adhesions, and their adhesions had higher quality and tenacity scores. Del-1 deficiency also led to enhanced inflammation mediators and collagen production. Finally, Del-1 supplementation decreased the incidence and severity of postoperative peritoneal adhesions. Taken together, these results indicate a protective role for Del-1 in postoperative peritoneal adhesion formation.

Developmental endothelial locus-1 (Del-1) antagonizes Interleukin-17-mediated allergic asthma.

Interleukin (IL)-17 is a major contributor to the pathogenesis of allergic asthma. Developmental endothelial locus-1 (Del-1) is an endothelial cell-secreted protein known to inhibit IL-17 expression. However, little is known about the association between Del-1 and IL-17 in the pathogenesis of allergic asthma. Using bronchoalveolar lavage fluid (BALF) and peripheral blood samples collected from allergic asthmatic patients and controls, we explored the role of Del-1 in relation to IL-17 in allergic asthma. We found that the negative correlation between Del-1 and IL-17 was significant in BALF of allergic asthmatics. Del-1 treatment inhibited the expression of IL-17, the differentiation of IL-17-secreting leukocytes and associated cytokines. Contrarily, IL-17 levels were increased after treatment with anti-Del-1 mAb. Consistent with this, Del-1 treatment led to downregulation of IL-5, CCL5 and IL-4, thus reducing secretion of eosinophil cationic protein. Furthermore, Del-1 significantly downregulated the expression of ICAM-1 and may have the potential to reduce leukocyte transendothelial migration. Our data demonstrate that Del-1 can negatively regulate IL-17 and its proinflammatory function, thereby limiting airway inflammation in allergic asthmatics, and suggest Del-1 as a potential candidate for prevention and treatment of allergic asthma.

Del-1 Expression as a Potential Biomarker in Triple-Negative Early Breast Cancer.

OBJECTIVE: A differential diagnostic role for plasma Del-1 was proposed for early breast cancer (EBC) in our previous study. We examined tumoral Del-1 expression and analyzed its prognostic impact among patients with EBC. METHODS: Del-1 mRNA expression was assessed in breast epithelial and cancer cells. Meanwhile, the tumoral expression of Del-1 was determined based on tissue microarrays and immunohistochemistry results from 440 patients. RESULTS: While a high Del-1 mRNA expression was found in all the breast cancer cell lines, the expression was significantly higher in MDA-MB-231. Tumoral expression of Del-1 was also significantly associated with a negative expression of estrogen receptor or progesterone receptor, and low expression of Ki-67, particularly in the case of triple-negative breast cancer (TNBC) (p < 0.036). Furthermore, a correlation was found between Del-1 expression and an aggressive histological grade, nuclear mitosis, and polymorphism, suggesting a possible role in tumor progression. In the survival analysis, a worse distant disease-free survival trend was noted for the group overexpressing Del-1. CONCLUSION: While all the investigated breast cancer cell lines exhibited Del-1 expression, the expression rate and intensity were specifically prominent in TNBC. In addition, based on its relationship to an unfavorable histology and worse survival trend, Del-1 could act as a molecular target in TNBC patients.

DEL1 protects against chondrocyte apoptosis through integrin binding.

BACKGROUND: Osteoarthritis (OA) is a debilitating disease process, affecting mobility and overall health of millions. Current treatment is for symptomatic relief and discovery of approaches to halt or reverse damage is imperative. Deletion of developmental endothelial locus-1 (Del1) has been shown to increase severity of OA in knockout mice. We examined the intracellular pathways involved in the ability of DEL1 to protect chondrocytes from apoptosis and anoikis and hypothesized that it functioned via integrin signaling. MATERIALS AND METHODS: Primary human chondrocytes were treated with various inducers of apoptosis, including anoikis, in the presence of added DEL1 or bovine serum albumin as control. Various inhibitors of integrin binding were examined for their effect on DEL1 activity. Downstream signaling pathway components were detected by immunoblotting. RESULTS: The addition of DEL1 protected chondrocytes from multiple inducers of apoptosis as measured by cell survival, terminal deoxynucleotidyl transferase dUTP nick end labeling and caspase 3/7 assays (P < 0.05). The effect of DEL1 was blocked by RGD peptides and by antibodies directed to integrin αVß3, but not by controls or antibody to integrin α1 (P < 0.05). Treatment with DEL1 promoted ERK and AKT activation when cells were attached, but only AKT activation under conditions of anoikis. CONCLUSIONS: DEL1 protected chondrocytes from apoptosis in response to activators of either the intrinsic or extrinsic pathways, and to anoikis. This effect was mediated primarily through integrin αVß3. This represents a therapeutic target for therapies to prevent cartilage degeneration in OA.

Del-1 overexpression potentiates lung cancer cell proliferation and invasion.

Developmental endothelial locus-1 (Del-1) is an endogenous anti-inflammatory molecule that is highly expressed in the lung and the brain and limits leukocyte migration to these tissues. We previously reported that the expression of Del-1 is positively regulated by p53 in lung endothelial cells. Although several reports have implicated the altered expression of Del-1 gene in cancer patients, little is known about its role in tumor cells. We here investigated the effect of Del-1 on the features of human lung carcinoma cells. Del-1 mRNA was found to be significantly decreased in the human lung adenocarcinoma cell lines A549 (containing wild type of p53), H1299 (null for p53) and EKVX (mutant p53), compared to in human normal lung epithelial BEAS-2B cells and MRC-5 fibroblasts. The decrease of Del-1 expression was dependent on the p53 activity in the cell lines, but not on the expression of p53. Neither treatment with recombinant human Del-1 protein nor the introduction of adenovirus expressing Del-1 altered the expression of the apoptosis regulators BAX, PUMA and Bcl-2. Unexpectedly, the adenovirus-mediated overexpression of Del-1 gene into the lung carcinoma cell lines promoted proliferation and invasion of the lung carcinoma cells, as revealed by BrdU incorporation and transwell invasion assays, respectively. In addition, overexpression of the Del-1 gene enhanced features of epithelial-mesenchymal transition (EMT), such as increasing vimentin while decreasing E-cadherin in A549 cells, and increases in the level of Slug, an EMT-associated transcription regulator. Our findings demonstrated for the first time that there are deleterious effects of high levels of Del-1 in lung carcinoma cells, and suggest that Del-1 may be used as a diagnostic or prognostic marker for cancer progression, and as a novel therapeutic target for lung carcinoma.

Deletion 1q43-44 in a patient with clinical diagnosis of Warburg-Micro syndrome.

Warburg-Micro syndrome (WARBM) is an autosomal recessive syndrome characterized by microcephaly, microphthalmia, microcornea, congenital cataracts, optic atrophy and central nervous system malformations. This syndrome is caused by mutations in the RAB3GAP1/2 and RAB18 genes, part of the Rab family, and in the TBC1D20 gene, which contributes to lipid droplet formation/metabolism. Here we present a patient with clinical diagnosis of WARBM syndrome, who did not have mutations in either the RAB3GAP1/2 genes, in the main exons of RAB18, nor in the TBC1D20 gene. However, the analysis with CGH-array detected a 9.6 Mb deletion at 1q43-qter. We performed a genotype-phenotype correlation using 20 previously published patients in whom the coordinates of the deleted regions were defined. The comparative analysis revealed that the current patient and three of the other 20 patients share the loss of six genes, four of which are related with the family of G proteins, and are strongly expressed in the brain, retina, heart and kidney. Consequently, their haploinsufficiency may result in different combinations of clinical alterations, including some of those of WARBM syndrome. In addition, the haploinsufficiency of other genes may contribute to other defects and clinical variability. Additionally, for the genotype-phenotype correlation, one must also consider molecular pathways that can result in the observed alterations. To early confirm a genetic diagnosis is essential for the patient and family. The current patient was considered as having a recessive syndrome, but since he had a "de novo" deletion, there was not an increased recurrence risk.

Interstitial 1p32.1p32.3 deletion in a patient with multiple congenital anomalies.

Interstitial deletions encompassing chromosome bands 1p32.1p32.3 are rare. Only nine unrelated patients with partially overlapping 1p32.1p32.3 deletions of variable size and position have been reported to date. We report on a 17-month-old boy with choanal atresia, hearing loss, urogenital anomalies, and microcephaly in whom an interstitial de novo deletion of 6.4 Mb was detected in 1p32.1p32.3 (genomic position chr1:54,668,618-61,113,264 according to GRCh37/hg19). The deleted region harbors 31 RefSeq genes. Notable genes in the region are PCSK9, haploinsufficiency of which caused low LDL cholesterol plasma levels in the patient, and DAB1, which is a candidate gene for cognitive deficits, microcephaly, and cerebral abnormalities such as ventriculomegaly and agenesis of the corpus callosum. Choanal atresia, microcephaly, and severe hearing loss were previously not known to be associated with 1p32 deletions. Our reported patient thus broadens the spectrum of clinical findings in this chromosome region and further facilitates genotype-phenotype correlations. Additional patients with overlapping deletions and/or point mutations in genes of this region need to be identified to elucidate the role of individual genes for the complex clinical manifestations.

Deficiency of developmental endothelial locus-1 (Del-1) aggravates bleomycin-induced pulmonary fibrosis in mice.

Pulmonary fibrosis is a lung disease wherein lung parenchyma is gradually and irreversibly replaced with collagen. The molecular pathogenesis of pulmonary fibrosis is not fully understood and the only effective treatment available is lung transplantation. To test if Del-1, an endogenous anti-inflammatory molecule, may be implicated in the development of pulmonary fibrosis, we induced pulmonary fibrosis in wild type (WT) and Del-1(-/-) mice by intratracheal administration of bleomycin. Del-1 expression in the lung was decreased in the WT mice treated with bleomycin compared to control mice. In addition, bleomycin-induced pulmonary fibrosis increased collagen deposition and TGF-ß production in the lung of Del-1(-/-) mice. Finally, Del-1(-/-) mice treated with bleomycin displayed higher weight loss and greater mortality than did WT mice identically treated. These findings suggest that Del-1 may negatively regulate development of pulmonary fibrosis. Further delineation of a role for Del-1 in the development of pulmonary fibrosis will broaden our understanding of the molecular pathogenesis of this disease and hopefully help develop potential therapeutics.

Novel inflammatory pathways in periodontitis.

New insights into the biological mechanisms involved in modulating periodontal inflammation and alveolar bone loss are paving the way for novel therapeutic strategies for periodontitis. The neutrophil adhesion cascade for transmigration in response to infection or inflammation is a key paradigm in immunity. Developmental endothelial locus-1 (Del-1) is one of several newly identified endogenous inhibitors of the leukocyte adhesion cascade. Del-1 competes with intercellular adhesion molecule-1 (ICAM-1) on endothelial cells for binding to the LFA-1 integrin on neutrophils, thereby regulating neutrophil recruitment and local inflammation. In animal periodontitis models, Del-1 deficiency resulted in severe inflammation and alveolar bone loss, but local treatment with recombinant Del-1 prevented neutrophil infiltration and bone loss. The expression of Del-1 is inhibited by the pro-inflammatory cytokine IL-17. Nucleic-acid-receptor-mediated inflammatory responses may be important in periodontal disease pathogenesis. Bacterial nucleic acids released during inflammation are detected by host microbial DNA sensors, e.g., Toll-like receptor-9 (TLR-9), leading to the activation of pro- and/or anti-inflammatory signaling pathways. DNA from periodontitis-associated bacteria induced pro-inflammatory cytokine production in human macrophage-like cells through the TLR-9 and NF-κB signaling pathways, but had less effect on human osteoblasts. Inhibition of TLR-9 signaling in human macrophages reduced cytokine production in response to P. gingivalis DNA. Differential expression of a polymorphic site in the TLR-9 gene promoter region and increased TLR-9 gene and protein expression were reported in chronic periodontitis. Further research to confirm that periodontal bacterial DNA contributes to destructive inflammation in vivo could provide alternative therapeutic targets to control periodontitis.