Sperm-carried IGF2 downregulated the expression of mitogens produced by Sertoli cells: A paracrine mechanism for regulating spermatogenesis?

Introduction: Insulin-like growth factor 2 (IGF2) mRNA has been found in human and mouse spermatozoa. It is currently unknown whether the IGF2 protein is expressed in human spermatozoa and, if so, its possible role in the cross-talk between germ and Sertoli cells (SCs) during spermatogenesis. Methods: To accomplish this, we analyzed sperm samples from four consecutive Caucasian men. Furthermore, to understand its role during the spermatogenetic process, porcine SCs were incubated with increasing concentrations (0.33, 3.33, and 10 ng/mL) of recombinant human IGF2 (rhIGF2) for 48 hours. Subsequently, the experiments were repeated by pre-incubating SCs with the non-competitive insulin-like growth factor 1 receptor (IGF1R) inhibitor NVP-AEW541. The following outcomes were evaluated: 1) Gene expression of the glial cell-line derived neurotrophic factor (GDNF), fibroblast growth factor 2 (FGF2), and stem cell factor (SCF) mitogens; 2) gene and protein expression of follicle-stimulating hormone receptor (FSHR), anti-Müllerian hormone (AMH), and inhibin B; 3) SC proliferation. Results: We found that the IGF2 protein was present in each of the sperm samples. IGF2 appeared as a cytoplasmic protein localized in the equatorial and post-acrosomal segment and with a varying degree of expression in each cell. In SCs, IGF2 significantly downregulated GDNF gene expression in a concentration-dependent manner. FGF2 and SCF were downregulated only by the highest concentration of IGF2. Similarly, IGF2 downregulated the FSHR gene and FSHR, AMH, and inhibin B protein expression. Finally, IGF2 significantly suppressed the SC proliferation rate. All these findings were reversed by pre-incubation with NVP-AEW541, suggesting an effect mediated by the interaction of IGF2 with the IGFR. Conclusion: In conclusion, sperm IGF2 seems to downregulate the expression of mitogens, which are known to be physiologically released by the SCs to promote gonocyte proliferation and spermatogonial fate adoption. These findings suggest the presence of paracrine regulatory mechanisms acting on the seminiferous epithelium during spermatogenesis, by which germ cells can influence the amount of mitogens released by the SCs, their sensitivity to FSH, and their rate of proliferation.

Internal carotid artery dissection in a patient with Ehlers-Danlos syndrome type IV: diagnosis and management / Disseccção da artéria carótida interna em paciente com síndrome de Ehlers-Danlos tipo IV: diagnóstico e manejo

Ehlers-Danlos syndrome (EDS) type IV, also known as vascular EDS, is an inherited connective tissue disorder with an estimated prevalence of 1/100,000 to 1/250,000. In EDS type IV, vascular complications may affect all anatomical areas, with a preference for large- and medium-sized arteries. Dissections of the vertebral and carotid arteries in their extra- and intra-cranial segments are typical. The authors report the case of a patient with EDS type IV for whom the diagnosis was established based on clinical signs and who developed internal carotid artery dissection at the age of 44 years. In the absence of a specific treatment for EDS type IV, medical interventions should focus on symptomatic relief, prophylactic measures, and genetic counseling. Invasive imaging techniques are contraindicated, and a conservative approach to vascular complications is usually recommended.

A síndrome de Ehlers-Danlos (EDS) tipo IV, também conhecida como EDS tipo vascular, é uma doença genética do tecido conjuntivo com prevalência estimada entre 1/100.000 e 1/250.000. Na EDS tipo IV, as complicações vasculares podem afetar todas as áreas anatômicas, com comprometimento preferencial de artérias de médio e grande diâmetros. Dissecções das artérias vertebrais e carótidas em seus segmentos intra e extracranianos são típicas. Os autores relatam o caso de uma paciente com EDS tipo IV na qual o diagnóstico sindrômico foi realizado com base nos achados clínicos e que desenvolveu dissecção da artéria carótida interna aos 44 anos. Na ausência de um tratamento específico para EDS tipo IV, a intervenção médica deve ser voltada para o tratamento sintomático, para medidas profiláticas e para o aconselhamento genético. Técnicas de imagem invasivas são contraindicadas e, geralmente, recomenda-se uma abordagem conservadora ao cuidar das complicações vasculares.