Dual action of exosomes derived from in vitro Aβ toxicity model: The role of age for pathological response

Exosomes released from different cell types of the central nervous system play an essential role in the pathogenesis of Alzheimer's disease (AD). In this study, we aimed to create an animal model by injecting exosomes that carry AD markers into the brain to shed light on the mechanism behind Alzheimer's pathology. Exosomes obtained from mouse Neuro2A, to which Aβ toxicity model applied, were used as a mediator to build an AD phenotype. For this purpose, exosomes were administered into hippocampal CA3 region of mice with different ages. Firstly, the possible role of exosomes on brain volume was analyzed. Then, neurons and astrocytes were evaluated for survival. In addition, the progenitor cells' differentiation capacity was investigated via BrdU staining. AKT signaling pathway components were examined to detect the molecular mechanisms behind the exosomal function. We found different responses in different age groups. Expression of APP upregulated only in young animals upon delivery of Aβ-exosomes. Interestingly, young animals represented increased numbers of neurons in the hippocampus, and neurogenesis was found to be restricted after Aβ-Ex injections. However, in relation to exosome administration, the glial intensity increased in aged animals. Lastly, phosphorylation of survival kinase AKT was downregulated due to the presence of Aβ in both young and old animals. The findings reveal that the exosomes from an in vitro Aβ toxicity model may induce different responses in an age-dependent manner. This study is the first to report the relationship between exosomal function and aging by evaluating the key molecules

The effect of COVID-19 on development of hair and nail disorders: a Turkish multicenter, controlled study

© 2022 the International Society of Dermatology.Background: A broad spectrum of skin diseases, including hair and nails, can be directly or indirectly triggered by COVID-19. It is aimed to examine the type and frequency of hair and nail disorders after COVID-19 infection. Methods: This is a multicenter study conducted on consecutive 2171 post-COVID-19 patients. Patients who developed hair and nail disorders and did not develop hair and nail disorders were recruited as subject and control groups. The type and frequency of hair and nail disorders were examined. Results: The rate of the previous admission in hospital due to COVID-19 was statistically significantly more common in patients who developed hair loss after getting infected with COVID-19 (P < 0.001). Telogen effluvium (85%) was the most common hair loss type followed by worsening of androgenetic alopecia (7%) after COVID-19 infection. The mean stress scores during and after getting infected with COVID-19 were 6.88 ± 2.77 and 3.64 ± 3.04, respectively, in the hair loss group and were 5.77 ± 3.18 and 2.81 ± 2.84, respectively, in the control group (P < 0.001, P < 0.001). The frequency of recurrent COVID-19 was statistically significantly higher in men with severe androgenetic alopecia (Grades 4–7 HNS) (P = 0.012; Odds ratio: 2.931 [1.222–7.027]). The most common nail disorders were leukonychia, onycholysis, Beau's lines, onychomadesis, and onychoschisis, respectively. The symptoms of COVID-19 were statistically significantly more common in patients having nail disorders after getting infected with COVID-19 when compared to the control group (P < 0.05). Conclusion: The development of both nail and hair disorders after COVID-19 seems to be related to a history of severe COVID-19