Citations

Objective— CD36 is a scavenger and antiangiogenic receptor that is important in atherothrombotic diseases, diabetes mellitus, cancer, and obesity. Lysophosphatidic acid, a phospholipid signaling mediator, abolishes endothelial cell responses to antiangiogenic proteins containing thrombospondin type 1 homology domains by downregulating endothelial CD36 transcription via protein kinase D1 (PKD-1) signaling. We aimed to understand mechanisms by which lysophosphatidic acid–mediated angiogenic signaling is integrated to regulate CD36 transcription and endothelial cell function via a nuclear transcriptional complex. Approach and Results— Microvascular endothelial cells expressing CD36 were used for studying angiogenic signaling and CD36 transcription. Gene transfection and transduction, RT-qPCR, avidin–biotin-conjugated DNA-binding assay, chromatin immunoprecipitation assay, co-immunoprecipitation, proximal ligation assay, and immunofluorescence microscopy showed that lysophosphatidic acid–mediated CD36 transcriptional repression involved PKD-1 signaling mediated formation of forkhead box protein O1–histone deacetylase 7 complex in the nucleus. Unexpectedly, turning off CD36 transcription initiated reprogramming microvascular endothelial cells to express ephrin B2, a critical molecular signature involved in angiogenesis and arteriogenesis. Spheroid-based angiogenesis and in vivo Matrigel angiogenesis assays indicated that angiogenic branching morphogenesis and in vivo angiogenesis were dependent on PKD-1 signaling. A mouse tumor angiogenesis model revealed enhanced PKD-1 signaling and expression of ephrin B2 and smooth muscle actin in neovessels of Lewis Lung Carcinomas, along with low-CD36 expression or CD36 deficiency. Conclusions— Lysophosphatidic acid/PKD-1 signaling leads to nuclear accumulation of histone deacetylase 7, where it interacts with forkhead box protein O1 to suppress endothelial CD36 transcription and mediates silencing of antiangiogenic switch, resulting in proangiogenic and proarteriogenic reprogramming. Targeting this signaling cascade could be a novel approach for ischemic cardiovascular disease and cancer.

1. If gastric acid is necessary for the absorption of dietary calcium, the total absence of gastric acid secretion that occurs in pernicious anaemia could result in bone loss. To investigate this, we measured calcium absorption and bone density in 21 postmenopausal women (ages 51–76 years) with pernicious anaemia and in 24 normal postmenopausal women (ages 51–79 years). 2. Relative to the normal women, in the women with pernicious anaemia the bone mineral density of the lumbar spine was decreased by 16% (P < 0.001). 3. After adjustment for age and body weight, lumbar spine bone mineral density correlated with the serum concentration of group 1 pepsinogens (a group of proteins produced by the gastric fundus) (r= 0.61, P < 0.01). 4. Despite achlorhydria, the women with pernicious anaemia had normal true fractional calcium absorption and normal serum levels of parathyroid hormone and 1,25-dihydroxyvitamin D. 5. We conclude that gastric acid is not required for the absorption of dietary calcium. Thus, the loss of cancellous bone must be caused by some mechanism yet to be identified.

Abstract CD36 is an endothelial cell (EC) receptor that mediates angiostatic activity and oxidative stress, which are important in ischemic disease and tumor progression. CD36 interacts with TSR domain proteins including thrombospondin-1. This results in a signal that is likely to initiate an antiangiogenic “switch," subsequently converting a growth factor-mediated proangiogenic response to an antiangiogenic response. However, in pathologic settings including malignant tumors, robust angiogenesis occurs despite the abundance of TSR-containing proteins in the microenvironment. This suggests that there is a mechanism by which TSR-mediated antiangiogenesis could be blunted via the localized downregulation of EC CD36 transcription. We previously reported that lysophosphatidic acid (LPA), a bioactive signaling phospholipid mediator, down-regulates microvascular EC (MVEC) CD36 transcription by protein kinase PKD-1 signaling via G protein coupled receptor LPA1,3. However, further elucidating the CD36 transcriptional mechanisms is critical to understanding the antiangiogenic switch. To this end, we recently discovered that obesity-derived LPA inhibited CD36 expression in tumor-associated ECs (TAECs). Similarly, inducing the constitutively active PKD-1 or PKD-CA expression also resulted in CD36 downregulation. Mechanistically, LPA treatment led to nuclear accumulation of PKD-1, HDAC7 and FoxO1. Furthermore, LPA-mediated PKD-1 signaling enhanced FoxO1-HDAC7 interaction in the nucleus. This interaction was attenuated with PKD-1 silencing. Intriguingly, doxycycline induced PKD-CA expression increased ephrin B2 expression and ERK activation, which are two critical “molecular signatures” involved in arteriogenesis. Functionally, FGF-2 induced a potent proangiogenic response even in the presence of TSP-1 in ECs pre-treated with LPA. Doxycycline induced PKD-CA expression stimulated robust arterial EC branching in a 3D spheroid assay. This angiogenic response was inhibited by a novel PKD-1 specific inhibitor. Moreover, in a mouse Lewis lung carcinoma model, we detected a minimal level of endothelial CD36 expression with robust tumor angiogenesis. The role of PKD-1 signaling in CD36 transcriptional repression and tumor arteriogenesis is a critical yet underexplored and underappreciated field. We propose that the LPA-PKD-FoxO1 signaling axis is essential for CD36 transcriptional repression and arteriogenic signaling and responses. The PKD-1 stimulated nuclear signaling network is critical to epigenetic suppression of CD36 transcription and silencing of CD36 antiangiogenic switch, subsequently turning on the angiogenic switch and stimulating the arteriogenic responses. Targeting the LPA-PKD1-FoxO1 signaling axis could have therapeutic potential in the ischemic disease and malignant tumors. Citation Format: Jacob D. Kohlenberg, Yiliang Chen, Brad Best, Peter Storz, Randall T. Peterson, Roy Silverstein, Bin Ren. A novel LPA-PKD1-FoxO1 pathway in endothelial cells provides an angiogenic switch via down-regulation of CD36 transcription and induction of arteriogenic responses . [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-338. doi:10.1158/1538-7445.AM2013-LB-338

The role of venous stasis syndrome (VSS) mechanisms (i.e. venous outflow obstruction [VOO] and venous valvular incompetence [VVI]) on quality of life (QoL) and activities of daily living (ADL) is unknown. The objective of this study was to test the hypotheses that venous thromboembolism (VTE),VSS,VOO and VVI are associated with reduced QoL and ADL. This study is a follow-up of an incident VTE case-control study nested within a population-based inception cohort of residents from Olmsted County, MN, USA, between 1966 and 1990. The study comprised 232 Olmsted County residents with a first lifetime VTE and 133 residents without VTE. Methods included a questionnaire and physical examination for VSS; vascular laboratory testing for VOO and VVI; assessment of QoL by SF36 and of ADL by pertinent sections from the Older Americans Resources and Services (OARS) and Arthritis Impact Measurement Scales (AIMS2) questionnaires. Of the 365 study participants, 232 (64%), 161 (44%), 43 (12%) and 136 (37%) had VTE, VSS, VOO and VVI, respectively. Prior VTE was associated with reduced ADL and increased pain, VSS with reduced physical QoL and increased pain, and VOO with reduced physical QoL and ADL.VVI was not associated with QoL or ADL. In conclusion,VSS and VOO are associated with worse physical QoL and increased pain. VOO and VTE are associated with impaired ADL. We hypothesize that rapid clearance of venous outflow obstruction in individuals with acute VTE will improve their QoL and ADL.

Abstract Venous stasis syndrome may complicate deep vein thrombosis (DVT; i.e. post-phlebitic syndrome), but, in most cases, venous stasis syndrome is not post-phlebitic. The objective of this study was to determine the risk factors (including prior DVT) for venous stasis syndrome, and to assess venous outflow obstruction and venous valvular incompetence as possible mechanisms for venous stasis syndrome. This was a case–control study nested within a population-based inception cohort. The study population consisted of 232 Olmsted County, MN residents with a first lifetime venous thromboembolism (VTE) and 133 residents without VTE. Measurements included a questionnaire and physical examination for venous stasis syndrome; strain gauge outflow plethysmography, venous continuous wave Doppler ultrasonography and passive venous drainage and refill testing for venous outflow obstruction and venous valvular incompetence. Altogether, 161 (44%), 43 (12%), and 136 (38%) subjects respectively, had venous stasis syndrome, venous outflow obstruction and venous valvular incompetence. Independent risk factors for venous stasis syndrome included increasing patient age and body mass index (BMI), prior DVT, longer time interval since DVT, and varicose veins. Both venous outflow obstruction ( p = 0.003) and venous valvular incompetence ( p < 0.0001) were strongly associated with venous stasis syndrome. Increasing age and prior DVT were significantly associated with venous outflow obstruction, while prior DVT, varicose veins and venous stasis syndrome diagnosed prior to the incident DVT were significantly associated with venous valvular incompetence. The risks of venous outflow obstruction, venous valvular incompetence and venous stasis syndrome were higher with left leg DVT. In conclusion, increasing patient age and BMI, prior DVT (particularly left leg DVT), longer time interval since DVT and varicose veins are independent risk factors for venous stasis syndrome. Venous stasis syndrome related to DVT is due to venous outflow obstruction and venous valvular incompetence, while venous stasis syndrome related to older age and to varicose veins is due to venous outflow obstruction and to venous valvular incompetence, respectively.

Objective: Our objective was to formulate practice guidelines for the treatment and prevention of pediatric obesity.Conclusions: We recommend defining overweight as body mass index (BMI) in at least the 85th percentile but &lt; the 95th percentile and obesity as BMI in at least the 95th percentile against routine endocrine studies unless the height velocity is attenuated or inappropriate for the family background or stage of puberty; referring patients to a geneticist if there is evidence of a genetic syndrome; evaluating for obesity-associated comorbidities in children with BMI in at least the 85th percentile; and prescribing and supporting intensive lifestyle (dietary, physical activity, and behavioral) modification as the prerequisite for any treatment. We suggest that pharmacotherapy (in combination with lifestyle modification) be considered in: 1) obese children only after failure of a formal program of intensive lifestyle modification; and 2) overweight children only if severe comorbidities persist despite intensive lifestyle modification, particularly in children with a strong family history of type 2 diabetes or premature cardiovascular disease. Pharmacotherapy should be provided only by clinicians who are experienced in the use of antiobesity agents and aware of the potential for adverse reactions. We suggest bariatric surgery for adolescents with BMI above 50 kg/m2, or BMI above 40 kg/m2 with severe comorbidities in whom lifestyle modifications and/or pharmacotherapy have failed. Candidates for surgery and their families must be psychologically stable and capable of adhering to lifestyle modifications. Access to experienced surgeons and sophisticated multidisciplinary teams who assess the benefits and risks of surgery is obligatory. We emphasize the prevention of obesity by recommending breast-feeding of infants for at least 6 months and advocating that schools provide for 60 min of moderate to vigorous daily exercise in all grades. We suggest that clinicians educate children and parents through anticipatory guidance about healthy dietary and activity habits, and we advocate for restricting the availability of unhealthy food choices in schools, policies to ban advertising unhealthy food choices to children, and community redesign to maximize opportunities for safe walking and bike riding to school, athletic activities, and neighborhood shopping.