Immunometric and functional measurement of endogenous vasoinhibin in human sera.

Introduction: Circulating levels of the antiangiogenic protein vasoinhibin, a fragment of prolactin, are of interest in vasoproliferative retinopathies, preeclampsia, and peripartum cardiomyopathy; however, it is difficult to determine the circulating levels of vasoinhibin due to the lack of quantitative assays. Methods: This study used human serum samples to assess the concentration and bioactivity of vasoinhibin using a novel enzyme-linked immunosorbent assay (ELISA) for human vasoinhibin, which employs an anti-vasoinhibin monoclonal antibody, a human umbilical vein endothelial cell (HUVEC) proliferation assay, and a chick chorioallantoic membrane (CAM) angiogenesis assay. Results: Serum samples from 17 pregnant women without (one group) and with preeclampsia and pregnancy induced hypertension (another group) demonstrated endogenous vasoinhibin concentrations in the range of 5-340 ng/ml. Immunoactive vasoinhibin levels were significantly higher in preeclampsia serum compared to healthy pregnancy serum (mean 63.09 ± 22.15 SD vs. 19.67 ± 13.34 ng/ml, p = 0.0003), as was the bioactive vasoinhibin level as determined by the HUVEC proliferation assay (56.12 ± 19.83 vs. 13.38 ± 4.88 ng/ml, p < 0.0001). There was a correlation between the concentration of vasoinhibin measured by ELISA and the HUVEC proliferation assay (Pearson r = 0.95, p < 0.0001). Healthy serum demonstrated a proangiogenic effect in the CAM assay (p < 0.05, compared to control), while serum from preeclamptic patients demonstrated an antiangiogenic effect (p < 0.05 vs. control), as did recombinant human vasoinhibin and a synthetic circular retro-inverse vasoinhibin analogue (CRIVi45-51). The antiangiogenic effects in the CAM assay and the inhibition of HUVEC proliferation were abolished by addition of the ELISA anti-vasoinhibin monoclonal antibody, but not by mouse IgG. Discussion: These results demonstrate the first quantitation of endogenous vasoinhibin in human sera and the elevation of it levels and antiangiogenic activity in sera from women with preeclampsia. The development and implementation of a quantitative assay for vasoinhibin overcomes a long-standing barrier and suggests the thorough clinical verification of vasoinhibin as a relevant biomarker.

Human Prolactin Point Mutations and Their Projected Effect on Vasoinhibin Generation and Vasoinhibin-Related Diseases.

BACKGROUND: A dysregulation of the generation of vasoinhibin hormones by proteolytic cleavage of prolactin (PRL) has been brought into context with diabetic retinopathy, retinopathy of prematurity, preeclampsia, pregnancy-induced hypertension, and peripartum cardiomyopathy. Factors governing vasoinhibin generation are incompletely characterized, and the composition of vasoinhibin isoforms in human tissues or compartments, such as the circulation, is unknown. The aim of this study was to determine the possible contribution of PRL point mutations to the generation of vasoinhibins as well as to project their role in vasoinhibin-related diseases. METHODS: Prolactin sequences, point mutations, and substrate specificity information about the PRL cleaving enzymes cathepsin D, matrix metalloproteinases 8 and 13, and bone-morphogenetic protein 1 were retrieved from public databases. The consequences of point mutations in regard to their possible effect on vasoinhibin levels were projected on the basis of a score indicating the suitability of a particular sequence for enzymatic cleavage that result in vasoinhibin generation. The relative abundance and type of vasoinhibin isoforms were estimated by comparing the relative cleavage efficiency of vasoinhibin-generating enzymes. RESULTS: Six point mutations leading to amino acid substitutions in vasoinhibin-generating cleavage sites were found and projected to either facilitate or inhibit vasoinhibin generation. Four mutations affecting vasoinhibin generation in cancer tissues were found. The most likely composition of the relative abundance of vasoinhibin isoforms is projected to be 15 > 17.2 > 16.8 > 17.7 > 18 kDa vasoinhibin. CONCLUSION: Prolactin point mutations are likely to influence vasoinhibin levels by affecting the proteolysis efficiency of vasoinhibin-generating enzymes and should be monitored in patients with vasoinhibin-related diseases. Attempts to characterize vasoinhibin-related diseases should include the 15, 17.2, 16.8, 17.7, and 18 kDa vasoinhibin isoforms.

Relación entre la prolactina y la retinopatía diabética / Relation between prolactin and diabetic retinopathy

La retinopatía diabética, como forma de microangiopatía, se caracteriza por la pérdida de los pericitos y de las células endoteliales, lo que conlleva a una alteración de la permeabilidad de los capilares retinianos. El factor de crecimiento del endotelio vascular estimula directamente el desarrollo de la vasculatura interna y externa del ojo, y actúa además como un factor de permeabilidad vascular. Por lo general, en condiciones naturales, existe un equilibrio entre las moléculas promotoras y las inhibidoras de la angiogénesis; sin embargo, cuando estas condiciones son alteradas, como sucede durante los episodios de hipoxia o inflamación, este equilibrio se rompe, e inclina la balanza hacia la formación de vasos anormales que se extienden y sangran dentro del vítreo, y pueden provocar el desprendimiento de la retina, con la consiguiente pérdida de la visión. Se han desarrollado algunos medicamentos antiangiogénicos que reducen la expresión del factor de crecimiento del endotelio vascular y del factor de crecimiento del tejido conectivo en las células del epitelio retiniano expuestas al estrés oxidativo. Se ha avanzado también en el desarrollo de otros medicamentos con acción antiangiogénica, con gran efectividad en su uso, solos o combinados con fotocoagulación láser y cirugía, pero son muy costosos, solo disponibles en centros muy especializados, y la vía de administración es intravítrea. En la actualidad se conoce que la hormona hipofisaria prolactina, puede prevenir la progresión y promover la regresión de la retinopatía diabética a través de su conversión proteolítica a vasoinhibinas, en particular, la fracción de menor...(AU)

Diabetic retinopathy, as a form of microangiopathy, is characterized by loss of pericytes and of endothelial cells, which causes alteration of the permeability of the retinal capillaries. The growth factor of the vascular endothelium directly stimulates the development of the internal and external vasculature of the eye, and additionally acts as a vascular permeability factor. In general, under natural conditions, there is a balance of promoting and inhibitory cells of angiogenesis. However, if these conditions are changed -as it happens during the hypoxia or inflammation episodes- this balance breaks and this tips the balance in favor of the formation of abnormal vessels that spread over and bleed into the vitreous, an event that may cause the retinal detachment and the resulting loss of vision. Some antiangiogenic drugs have been developed to reduce the expression of the vascular endothelium growth factor and of the connective tissue growth factor in the retinal epithelium cells under oxidative stress. Advances have also been made in the development of other antiangiogenic drugs of high effectiveness when they are used alone or combined with laser photocoagulation and surgery, but they are very expensive, available only in highly specialized centers and with intravitreal administration. Nowadays, it is known that hyphophysial hormone called prolactin can prevent the progress and encourage the regression of diabetic retinopathy through its proteolytic conversion to vasoinhibins, particularly, the lowest molecular weight fraction (16 kDa-prolactin). This fraction has an important antiangiogenic action since it blocks the stimulation of angiogenesis induced by several factors such as the vascular endothelium growth factor and the fibroblastic growth factor in the proliferation of the endothelial cells, all of which brings the possibilities of new drugs for the treatment of proliferative retinopathy. These are the aspects addressed in the present review(AU)

Relación entre la prolactina y la retinopatía diabética / Relation between prolactin and diabetic retinopathy

La retinopatía diabética, como forma de microangiopatía, se caracteriza por la pérdida de los pericitos y de las células endoteliales, lo que conlleva a una alteración de la permeabilidad de los capilares retinianos. El factor de crecimiento del endotelio vascular estimula directamente el desarrollo de la vasculatura interna y externa del ojo, y actúa además como un factor de permeabilidad vascular. Por lo general, en condiciones naturales, existe un equilibrio entre las moléculas promotoras y las inhibidoras de la angiogénesis; sin embargo, cuando estas condiciones son alteradas, como sucede durante los episodios de hipoxia o inflamación, este equilibrio se rompe, e inclina la balanza hacia la formación de vasos anormales que se extienden y sangran dentro del vítreo, y pueden provocar el desprendimiento de la retina, con la consiguiente pérdida de la visión. Se han desarrollado algunos medicamentos antiangiogénicos que reducen la expresión del factor de crecimiento del endotelio vascular y del factor de crecimiento del tejido conectivo en las células del epitelio retiniano expuestas al estrés oxidativo. Se ha avanzado también en el desarrollo de otros medicamentos con acción antiangiogénica, con gran efectividad en su uso, solos o combinados con fotocoagulación láser y cirugía, pero son muy costosos, solo disponibles en centros muy especializados, y la vía de administración es intravítrea. En la actualidad se conoce que la hormona hipofisaria prolactina, puede prevenir la progresión y promover la regresión de la retinopatía diabética a través de su conversión proteolítica a vasoinhibinas, en particular, la fracción de menor peso molecular (16 kDa-Prolactina), con importante acción antiangiogénica, bloqueando la estimulación de la angiogénesis inducida por varios factores, como el factor de crecimiento del endotelio vascular, y el factor de crecimiento fibroblástico en la proliferación de las células endoteliales, lo cual abre la esperanza de nuevos medicamentos para el tratamiento de la retinopatía proliferativa, aspectos sobre los que trata la presente revisión(AU)

Diabetic retinopathy, as a form of microangiopathy, is characterized by loss of pericytes and of endothelial cells, which causes alteration of the permeability of the retinal capillaries. The growth factor of the vascular endothelium directly stimulates the development of the internal and external vasculature of the eye, and additionally acts as a vascular permeability factor. In general, under natural conditions, there is a balance of promoting and inhibitory cells of angiogenesis. However, if these conditions are changed -as it happens during the hypoxia or inflammation episodes- this balance breaks and this tips the balance in favor of the formation of abnormal vessels that spread over and bleed into the vitreous, an event that may cause the retinal detachment and the resulting loss of vision. Some antiangiogenic drugs have been developed to reduce the expression of the vascular endothelium growth factor and of the connective tissue growth factor in the retinal epithelium cells under oxidative stress. Advances have also been made in the development of other antiangiogenic drugs of high effectiveness when they are used alone or combined with laser photocoagulation and surgery, but they are very expensive, available only in highly specialized centers and with intravitreal administration. Nowadays, it is known that hyphophysial hormone called prolactin can prevent the progress and encourage the regression of diabetic retinopathy through its proteolytic conversion to vasoinhibins, particularly, the lowest molecular weight fraction (16 kDa-prolactin). This fraction has an important antiangiogenic action since it blocks the stimulation of angiogenesis induced by several factors such as the vascular endothelium growth factor and the fibroblastic growth factor in the proliferation of the endothelial cells, all of which brings the possibilities of new drugs for the treatment of proliferative retinopathy. These are the aspects addressed in the present review(AU)

Bromocriptine as a new therapeutic agent for peripartum cardiomyopathy.

Peripartum cardiomyopathy (PPCM) is a poorly understood, rare disorder in which left ventricular systolic dysfunction and symptoms of heart failure occur between the last month of pregnancy and the first 5 months postpartum. Recent data suggest that uncontrolled oxidative stress leads to the activation of the prolactin cleaving enzyme cathepsin D that in turn leads to an increase in a cleaved 16 kDa prolactin. This cleaved form that has an angiostatic and proapoptotic role appears to drive the disease by adversely impacting the endothelium and cardiomyocyte. Bromocriptine that reduces the prolactin production by dopamine agonist actions may improve outcomes in patients with peripartum cardiomyopathy by eliminating the cleaved form of prolactin despite the activation of the cleaving enzyme. In limited case reports and proof of concept studies use of bromocriptine in the early stages has been shown to improve outcomes in patients with peripartum cardiomyopathy. However, larger randomized control study is still awaited.