Calcineurin A beta deficiency ameliorates HFD-induced hypothalamic astrocytosis in mice

Obesity-induced blood-brain barrier dysfunction: phenotypes and mechanisms

Obesity, a burgeoning global health issue, is increasingly recognized for its detrimental effects on the central nervous system, particularly concerning the integrity of the blood-brain barrier (BBB). This manuscript delves into the intricate relationship between obesity and BBB dysfunction, elucidating the underlying phenotypes and molecular mechanisms. We commence with an overview of the BBB's critical role in maintaining cerebral homeostasis and the pathological alterations induced by obesity. By employing a comprehensive literature review, we examine the structural and functional modifications of the BBB in the context of obesity, including increased permeability, altered transport mechanisms, and inflammatory responses. The manuscript highlights how obesity-induced systemic inflammation and metabolic dysregulation contribute to BBB disruption, thereby predisposing individuals to various neurological disorders. We further explore the potential pathways, such as oxidative stress and endothelial cell dysfunction, that mediate these changes. Our discussion culminates in the summary of current findings and the identification of knowledge gaps, paving the way for future research directions. This review underscores the significance of understanding BBB dysfunction in obesity, not only for its implications in neurodegenerative diseases but also for developing targeted therapeutic strategies to mitigate these effects.

Long-term normalization of calcineurin activity in model mice rescues Pin1 and attenuates Alzheimer's phenotypes without blocking peripheral T cell IL-2 response

BACKGROUND

Current treatments for Alzheimer's disease (AD) have largely failed to yield significant therapeutic benefits. Novel approaches are desperately needed to help address this immense public health issue. Data suggests that early intervention at the first stages of mild cognitive impairment may have a greater chance for success. The calcineurin (CN)-Pin1 signaling cascade can be selectively targeted with tacrolimus (FK506), a highly specific, FDA-approved CN inhibitor used safely for > 20 years in solid organ transplant recipients. AD prevalence was significantly reduced in solid organ recipients treated with FK506.

METHODS

Time release pellets were used to deliver constant FK506 dosage to APP/PS1 mice without deleterious manipulation or handling. Immunofluorescence, histology, molecular biology, and behavior were used to evaluate changes in AD pathology.

RESULTS

FK506 can be safely and consistently delivered into juvenile APP/PS1 mice via time-release pellets to levels roughly seen in transplant patients, leading to the normalization of CN activity and reduction or elimination of AD pathologies including synapse loss, neuroinflammation, and cognitive impairment. Pin1 activity and function were rescued despite the continuing presence of high levels of transgenic Aβ42. Indicators of neuroinflammation including Iba1 positivity and IL-6 production were also reduced to normal levels. Peripheral blood mononuclear cells (PBMC) obtained during treatment or splenocytes isolated at euthanasia activated normally after mitogens.

CONCLUSIONS

Low-dose, constant FK506 can normalize CNS CN and Pin1 activity, suppress neuroinflammation, and attenuate AD-associated pathology without blocking peripheral IL-2 responses making repurposed FK506 a viable option for early, therapeutic intervention in AD.

Effects of diabetes on microglial physiology: a systematic review of in vitro, preclinical and clinical studies

Diabetes mellitus is a heterogeneous chronic metabolic disorder characterized by the presence of hyperglycemia, commonly preceded by a prediabetic state. The excess of blood glucose can damage multiple organs, including the brain. In fact, cognitive decline and dementia are increasingly being recognized as important comorbidities of diabetes. Despite the largely consistent link between diabetes and dementia, the underlying causes of neurodegeneration in diabetic patients remain to be elucidated. A common factor for almost all neurological disorders is neuroinflammation, a complex inflammatory process in the central nervous system for the most part orchestrated by microglial cells, the main representatives of the immune system in the brain. In this context, our research question aimed to understand how diabetes affects brain and/or retinal microglia physiology. We conducted a systematic search in PubMed and Web of Science to identify research items addressing the effects of diabetes on microglial phenotypic modulation, including critical neuroinflammatory mediators and their pathways. The literature search yielded 1327 records, including 18 patents. Based on the title and abstracts, 830 papers were screened from which 250 primary research papers met the eligibility criteria (original research articles with patients or with a strict diabetes model without comorbidities, that included direct data about microglia in the brain or retina), and 17 additional research papers were included through forward and backward citations, resulting in a total of 267 primary research articles included in the scoping systematic review. We reviewed all primary publications investigating the effects of diabetes and/or its main pathophysiological traits on microglia, including in vitro studies, preclinical models of diabetes and clinical studies on diabetic patients. Although a strict classification of microglia remains elusive given their capacity to adapt to the environment and their morphological, ultrastructural and molecular dynamism, diabetes modulates microglial phenotypic states, triggering specific responses that include upregulation of activity markers (such as Iba1, CD11b, CD68, MHC-II and F4/80), morphological shift to amoeboid shape, secretion of a wide variety of cytokines and chemokines, metabolic reprogramming and generalized increase of oxidative stress. Pathways commonly activated by diabetes-related conditions include NF-κB, NLRP3 inflammasome, fractalkine/CX3CR1, MAPKs, AGEs/RAGE and Akt/mTOR. Altogether, the detailed portrait of complex interactions between diabetes and microglia physiology presented here can be regarded as an important starting point for future research focused on the microglia-metabolism interface.

Role of astroglia in diet-induced central neuroplasticity

Obesity, characterized by increased adiposity that develops when energy intake outweighs expenditure, is rapidly becoming a serious health crisis that affects millions of people worldwide and is associated with severe comorbid disorders including hypertension, cardiovascular disease, and type II diabetes. Obesity is also associated with the dysregulation of central neurocircuits involved in the control of autonomic, metabolic, and cognitive functions. Systemic inflammation associated with diet-induced obesity (DIO) has been proposed to be responsible for the development of these comorbidities as well as the dysregulation of central neurocircuits. A growing body of evidence suggests, however, that exposure to a high-fat diet (HFD) may cause neuroinflammation and astroglial activation even before systemic inflammation develops, which may be sufficient to cause dysregulation of central neurocircuits involved in energy homeostasis before the development of obesity. The purpose of this review is to summarize the current literature exploring astroglial-dependent modulation of central circuits following exposure to HFD and DIO, including not only dysregulation of neurocircuits involved in energy homeostasis and feeding behavior, but also the dysregulation of learning, memory, mood, and reward pathways.