RESUMO
The term inflammatory arthritis defines a family of diseases, including rheumatoid arthritis (RA), caused by an overactive immune system, and influenced by host aspects including sex, reproductive state, and stress. Prolactin (PRL) is a sexually dimorphic, reproductive, stress-related hormone long-linked to RA under the general assumption that it aggravates the disease. However, this conclusion remains controversial since PRL has both negative and positive outcomes in RA that may depend on the hormone circulating levels, synthesis by joint tissues, and complex interactions at the inflammatory milieu. The inflamed joint is rich in matrix metalloproteases that cleave PRL to vasoinhibin, a PRL fragment with proinflammatory effects and the ability to inhibit the hyperpermeability and growth of blood vessels. This review addresses this field with the idea that explanatory mechanisms lie within the PRL/vasoinhibin axis, an integrative framework influencing not only the levels of systemic and local PRL, but also the proteolytic conversion of PRL to vasoinhibin, as vasoinhibin itself has dual actions on joint inflammation. In this review, we discuss recent findings from mouse models suggesting the upregulation of endogenous vasoinhibin by the pro-inflammatory environment and showing dichotomous actions and signaling mechanisms of PRL and vasoinhibin on joint inflammation that are cell-specific and context-dependent. We hypothesize that these opposing actions work together to balance the inflammatory response and provide new insights for understanding the pathophysiology of RA and the development of new treatments.
Assuntos
Artrite Reumatoide , Prolactina , Animais , Inflamação , Camundongos , Prolactina/metabolismo , Ligação ProteicaRESUMO
BACKGROUND: Vasoinhibin, a protein derived from prolactin, regulates various vascular functions including endothelial cell survival. Of note, vasoinhibin is present in the central nervous system, where it triggers neuroendocrine and behavioral responses to stress. Moreover, vasoinhibin compromises nerve growth factor (NGF)-induced neurite outgrowth in primary sensory neurons of the peripheral nervous system. Nonetheless, information on the functions of vasoinhibin in developing neurons remains limited. The present study explored whether vasoinhibin affects the neurotrophic actions of NGF by measuring the cell differentiation and survival of PC12 pheochromocytoma cells. METHODS: The effects of recombinant or lentiviral vector-transduced human vasoinhibin were tested on differentiating PC12 cells. Neurite outgrowth was quantified by measuring their length and density. The MTT assay was employed to assess cell viability, and ELISA was used to quantify DNA fragmentation as an index of apoptosis. Phosphorylated Akt and ERK1/2 were analyzed by Western blotting. RESULTS: The addition of a human recombinant vasoinhibin, and the transduction of a lentiviral vector carrying a human vasoinhibin sequence, significantly reduced NGF-induced neurite outgrowth, cell survival, and phosphorylation of Akt and ERK1/2, and increased DNA fragmentation and caspase 3 activation in PC12 cells. CONCLUSIONS: Vasoinhibin downregulates NGF-induced differentiation and survival of PC12 cells, blocking tropomyosin receptor kinase A-triggered signaling pathways and increasing apoptosis. These results establish that vasoinhibin interaction with NGF and other neurotrophins may be critical in mediating pathways involved in neuronal survival and differentiation.
Assuntos
Neoplasias das Glândulas Suprarrenais/patologia , Proteínas de Ciclo Celular/fisiologia , Diferenciação Celular , Fator de Crescimento Neural/farmacologia , Feocromocitoma/patologia , Neoplasias das Glândulas Suprarrenais/genética , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/farmacologia , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/genética , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Células HEK293 , Humanos , Crescimento Neuronal/efeitos dos fármacos , Crescimento Neuronal/genética , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Células PC12 , Feocromocitoma/genética , Ratos , Proteínas Recombinantes/genética , Proteínas Recombinantes/farmacologia , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , TransfecçãoRESUMO
Rheumatoid arthritis (RA) is a chronic, autoimmune, inflammatory disease destroying articular cartilage and bone. The female preponderance and the influence of reproductive states in RA have long linked this disease to sexually dimorphic, reproductive hormones such as prolactin (PRL). PRL has immune-enhancing properties and increases in the circulation of some patients with RA. However, PRL also suppresses the immune system, stimulates the formation and survival of joint tissues, acquires antiangiogenic properties upon its cleavage to vasoinhibins, and protects against joint destruction and inflammation in the adjuvant-induced model of RA. This review addresses risk factors for RA linked to PRL, the effects of PRL and vasoinhibins on joint tissues, blood vessels, and immune cells, and the clinical and experimental data associating PRL with RA. This information provides important insights into the pathophysiology of RA and highlights protective actions of the PRL/vasoinhibin axis that could lead to therapeutic benefits.
Assuntos
Artrite Reumatoide/imunologia , Artrite Reumatoide/patologia , Cartilagem Articular/patologia , Inflamação/patologia , Articulações/patologia , Prolactina/imunologia , Inibidores da Angiogênese/imunologia , Animais , Artrite Reumatoide/epidemiologia , Artrite Reumatoide/fisiopatologia , Cartilagem Articular/irrigação sanguínea , Cartilagem Articular/imunologia , Cartilagem Articular/fisiopatologia , Feminino , Humanos , Tolerância Imunológica , Imunidade Celular , Inflamação/epidemiologia , Inflamação/imunologia , Inflamação/fisiopatologia , Articulações/irrigação sanguínea , Articulações/imunologia , Articulações/fisiopatologia , Masculino , Reprodução , Fatores Sexuais , Estresse Fisiológico , Estresse PsicológicoRESUMO
Adeno-associated virus (AAV) vector-mediated delivery of inhibitors of blood-retinal barrier breakdown (BRBB) offers promise for the treatment of diabetic macular edema. Here, we demonstrated a reversal of blood-retinal barrier pathology mediated by AAV type 2 (AAV2) vectors encoding vasoinhibin or soluble VEGF receptor 1 (sFlt-1) when administered intravitreally to diabetic rats. Efficacy and safety of the AAV2 vasoinhibin vector were tested by monitoring its effect on diabetes-induced changes in the retinal vascular bed and thickness, and in the electroretinogram (ERG). Also, the transduction of AAV2 vectors and expression of AAV2 receptors and co-receptors were compared between the diabetic and the non-diabetic rat retinas. AAV2 vasoinhibin or AAV2 sFlt-1 vectors were injected intravitreally before or after enhanced BRBB due to diabetes induced by streptozotocin. The BRBB was examined by the Evans blue method, the vascular bed by fluorescein angiography, expression of the AAV2 EGFP reporter vector by confocal microscopy, and the AAV2 genome, expression of transgenes, receptors, and co-receptors by quantitative PCR. AAV2 vasoinhibin and sFlt-1 vectors inhibited the diabetes-mediated increase in BRBB when injected after, but not before, diabetes was induced. The AAV2 vasoinhibin vector decreased retinal microvascular abnormalities and the diabetes-induced reduction of the B-wave of the ERG, but it had no effect in non-diabetic controls. Also, retinal thickness was not altered by diabetes or by the AAV2 vasoinhibin vector. The AAV2 genome, vasoinhibin and sFlt-1 transgenes, and EGFP levels were higher in the retinas from diabetic rats and were associated with an elevated expression of AAV2 receptors (syndecan, glypican, and perlecan) and co-receptors (fibroblast growth factor receptor 1, αvß5 integrin, and hepatocyte growth factor receptor). We conclude that retinal transduction and efficacy of AAV2 vectors are enhanced in diabetes, possibly due to their elevated cell entry. AAV2 vectors encoding vasoinhibin and sFlt-1 may be desirable gene therapeutics to target diabetic retinopathy and macular edema.
Assuntos
Proteínas de Ciclo Celular/genética , Dependovirus/genética , Diabetes Mellitus Experimental/terapia , Retinopatia Diabética/terapia , Terapia Genética , Retina/metabolismo , Receptor 1 de Fatores de Crescimento do Endotélio Vascular/genética , Animais , Barreira Hematorretiniana , Vetores Genéticos , Proteoglicanas de Heparan Sulfato/análise , Masculino , Ratos , Ratos Wistar , EstreptozocinaRESUMO
The hormone prolactin (PRL) regulates neuroendocrine and emotional stress responses. It is found in the hypothalamus, where the protein is partially cleaved to vasoinhibins, a family of N-terminal antiangiogenic PRL fragments ranging from 14 to 18kDa molecular masses, with unknown effects on the stress response. Here, we show that the intracerebroventricular administration of a recombinant vasoinhibin, containing the first 123 amino acids of human PRL that correspond to a 14kDa PRL, exerts anxiogenic and depressive-like effects detected in the elevated plus-maze, the open field, and the forced swimming tests. To investigate whether stressor exposure affects the generation of vasoinhibins in the hypothalamus, the concentrations of PRL mRNA, PRL, and vasoinhibins were evaluated in hypothalamic extracts of virgin female rats immobilized for 30min at different time points after stress onset. The hypothalamic levels of PRL mRNA and protein were higher at 60min but declined at 360min to levels seen in non-stressed animals. The elevation of hypothalamic PRL did not correlate with the stress-induced increase in circulating PRL levels, nor was it modified by blocking adenohypophyseal PRL secretion with bromocriptine. A vasoinhibin having an electrophoretic migration rate corresponding to 17kDa was detected in the hypothalamus. Despite the elevation in hypothalamic PRL, the levels of this hypothalamic vasoinhibin were similar in stressed and non-stressed rats. Stress reduced the rate of cleavage of PRL to this vasoinhibin as shown by the incubation of recombinant PRL with hypothalamic extracts from stressed rats. These results suggest that vasoinhibins are potent anxiogenic and depressive factors and that stress increases PRL levels in the hypothalamus partly by reducing its conversion to vasoinhibins. The reciprocal interplay between PRL and vasoinhibins may represent an effective mechanism to regulate anxiety and depression.
Assuntos
Comportamento Animal/efeitos dos fármacos , Proteínas de Ciclo Celular/farmacologia , Hipotálamo/metabolismo , Prolactina/metabolismo , Animais , Ansiedade/metabolismo , Comportamento Animal/fisiologia , Depressão/metabolismo , Feminino , Ratos , Ratos WistarRESUMO
Arthritic disorders are family of diseases that have existed since vertebrate life began. Their etiology is multifactorial with genetic, environmental, and gender factors driving chronic joint inflammation. Prolactin is a sexually dimorphic hormone in mammals that can act to both promote and ameliorate rheumatic diseases. It is found in all vertebrate groups where it exerts a wide diversity of actions. This review briefly addresses the presence and features of arthritic diseases in vertebrates, the effects of PRL on joint tissues and immune cells, and whether PRL actions could have contributed to the ubiquity of arthritis in nature. This comparative approach highlights the value of PRL as a biologically conserved factor influencing the development and progression of arthritis.