In addition to memory impairments, patients with Alzheimer's disease (AD) exhibit a number of behavioural and psychological symptoms that can affect social interactions over the course of the disease. While altered social interactions have been demonstrated in a number of mouse models of AD, many models only recapitulate the initial stages of the disease, and these behavioural changes have yet to be examined over the course of disease progression. By performing a longitudinal study using the 5xFAD mouse model, we have demonstrated that transgenic females exhibit progressive alterations in social investigation compared to wild-type controls. Transgenic females exhibited an age-related reduction in interest for social odours, as well as reduced investigative behaviours towards novel conspecifics in a novel environment. However, transgenic mice exhibited no obvious olfactory deficits, nor any changes in scent-marking behaviour compared to wild-type controls, indicating that changes in investigative behaviour were due to motivation to engage with a social stimulus. This evidence suggests that transgenic 5xFAD females exhibit increased social anxiety in novel environments compared to wildtype controls. Overall, transgenic 5xFAD female mice mimic some features of social withdrawal observed in human AD patients suggesting this strain may be suitable for modelling aspects of the social dysfunction observed in human patients.

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In addition to memory impairments, patients with Alzheimer's disease (AD) exhibit a number of behavioural and psychological symptoms that can affect social interactions over the course of the disease. While altered social interactions have been demonstrated in a number of mouse models of AD, many models only recapitulate the initial stages of the disease, and these behavioural changes have yet to be examined over the course of disease progression. By performing a longitudinal study using the 5xFAD mouse model, we have demonstrated that transgenic females exhibit progressive alterations in social investigation compared to wild-type controls. Transgenic females exhibited an age-related reduction in interest for social odours, as well as reduced investigative behaviours towards novel conspecifics in a novel environment. However, transgenic mice exhibited no obvious olfactory deficits, nor any changes in scent-marking behaviour compared to wild-type controls, indicating that changes in investigative behaviour were due to motivation to engage with a social stimulus. This evidence suggests that transgenic 5xFAD females exhibit increased social anxiety in novel environments compared to wildtype controls. Overall, transgenic 5xFAD female mice mimic some features of social withdrawal observed in human AD patients suggesting this strain may be suitable for modelling aspects of the social dysfunction observed in human patients.Keywords social behaviors; transgenic mice; 5xFAD, Alzheimer's disease Evidence for increased sociability in the 3xTg-AD mouse model has also been presented [19], but the Tg2576 strain exhibits no effect of AD pathology on sociability [17]. Overall, these results indicate that some mouse models of AD exhibit changes in social behaviour that include altered aggression and sociability. However, many transgenic mouse models of AD (e.g., 3xTg-AD, APP/PS1, and Tg2576) exhibit a slow rate of amyloid beta (Ab) accumulation and can only model the initial phase of the disease, which does not include widespread neurodegeneration [20].By comparison, the 5xFAD strain exhibits rapid development and progression of amyloid plaques and neurodegeneration, allowing effects to be tracked across early-, mid-, and late-stage disease progression [20,21]. There is increasing evidence that 5xFAD mice exhibit a range of social deficits that, in some cases, mirror the social symptoms presented by AD patients. Transgenic 5xFAD 9-month-old male mice and 12-month-old male and female mice demonstrate deficits in nest building, a behaviour that has been associated with affiliative behaviours [22,23]; however, they also engage in more homecage social behaviours than wild-type controls [24]. Transgenic 5xFAD mice also exhibit impaired social recognition memory at 9-months of age [24], consistent with memory deficits exhibited in this strain and human AD patients.While these results suggest that the 5xFAD strain exhibit social deficits, a comprehensive investigation of social behaviours in this strain has not yet been performed. The p...

Introduction: Graft-versus-host disease (GVHD) is caused by a pathologic and destructive response of the organism as a result of the interaction between donor immunocompetent T lymphocytes and the recipient tisular antigens. It´s considered the most serious complication of hematopoietic stem cell transplantation, most frequently described after bone marrow transplantation (BMT). The skin is usually the first and most commonly affected organ, in both acute and chronic, with a variable clinical spectrum of presentation. Objective: To report a case of vitiligo as a manifestation of cutaneous chronic GVHD, a low prevalence sign, which recognition could help to suspect this severe complication. Case report: 8 years old male, diagnosed with acute lymphoblastic leukemia (ALL) at 3 years old, had a combined medullary and central nervous system (NCS) relapse with minimal positive disease 3 years afterwards. After 4 years ALL was diagnosed, he received an allogeneic bone marrow transplant. Seven months after the BMT he presented multiple melanocytic nevi with peripheral hypopigmentation, and some isolated asymptomatic, confluent achromic macules on the face, trunk and limbs. The skin biopsy was compatible with chronic vitiligo and sclerodermiform type GVHD. He received topical treatment with Tacrolimus, achieving clinical stabilization. Conclusions: GVHD leads to the appearance of autoantibodies that could act as a trigger in the onset of autoimmune diseases, such as vitiligo. Consequently it could explain this poorly described manifestation in the literature of chronic cutaneous GVHD.

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