Microglia, the resident macrophages of the central nervous system, rapidly activate in nearly all kinds of neurological diseases. These activated microglia become highly motile, secreting inflammatory cytokines, migrating to the lesion area, and phagocytosing cell debris or damaged neurons. During the past decades, the secretory property and chemotaxis of microglia have been well-studied, while relatively less attention has been paid to microglial phagocytosis. So far there is no obvious concordance with whether it is beneficial or detrimental in tissue repair. This review focuses on phagocytic phenotype of microglia in neurological diseases such as Alzheimer’s disease, multiple sclerosis, Parkinson’s disease, traumatic brain injury, ischemic and other brain diseases. Microglial morphological characteristics, involved receptors and signaling pathways, distribution variation along with time and space changes, and environmental factors that affecting phagocytic function in each disease are reviewed. Moreover, a comparison of contributions between macrophages from peripheral circulation and the resident microglia to these pathogenic processes will also be discussed.

We have examined the trafficking and metabolism of the beta-amyloid precursor protein (APP), an APP homolog (APLP1), and TrkB in neurons that lack PS1. We report that PS1-deficient neurons fail to secrete Abeta, and that the rate of appearance of soluble APP derivatives in the conditioned medium is increased. Remarkably, carboxyl-terminal fragments (CTFs) derived from APP and APLP1 accumulate in PS1-deficient neurons. Hence, PS1 plays a role in promoting intramembrane cleavage and/or degradation of membrane-bound CTFs. Moreover, the maturation of TrkB and BDNF-inducible TrkB autophosphorylation is severely compromised in neurons lacking PS1. We conclude that PS1 plays an essential role in modulating trafficking and metabolism of a selected set of membrane and secretory proteins in neurons.

Uric acid is the product of purine metabolism. It is known that hyperuricemia, defined as high levels of blood uric acid, is the major etiological factor of gout. A number of epidemiological reports have increasingly linked hyperuricemia with cardiovascular and neurological diseases. Studies highlighting the pathogenic mechanisms of uric acid point to an inflammatory response as the primary mechanism for inducing gout and possibly contributing to uric acid's vascular effects. Monosodium urate (MSU) crystals induce an inflammatory reaction, which are recognized by Toll-like receptors (TLRs). These TLRs then activate NALP3 inflammasome. MSU also triggers neutrophil activation and further produces immune mediators, which lead to a proinflammatory response. In addition, soluble uric acid can also mediate the generation of free radicals and function as a pro-oxidant. This review summarizes the epidemiological studies of hyperuricemia and cardiovascular disease, takes a brief look at hyperuricemia and its role in neurological diseases, and highlights the studies of the advanced pathological mechanisms of uric acid and inflammation.

Survivors of severe acute kidney injury remain at high risk of death well after apparent recovery from the initial insult. Here we determine whether early nephrology follow-up after a hospitalization complicated by severe acute kidney injury associates with patient survival. This consisted of a cohort study of all hospitalized adults in Ontario from 1996 to 2008 with acute kidney injury who received temporary inpatient dialysis and survived for 90 days following discharge independent from dialysis. Propensity scores were used to match individuals with early nephrology follow-up, defined as a visit with a nephrologist within 90 days of discharge, to those without. The outcome was time to all-cause mortality of 3877 patients who met the eligibility criteria within a maximum follow-up of 2 years. A total of 1583 patients had early nephrology follow-up of whom 1184 were successfully matched 1:1 to those not receiving early follow-up. The incidence of all-cause mortality was lower in those patients with early nephrology follow-up compared with those without (8.4 compared with 10.6 per 100-patient years, hazard ratio 0.76 (95% CI: 0.62-0.93)). Thus, early nephrology follow-up after hospitalization with acute kidney injury and temporary dialysis was associated with improved survival. This finding requires definitive testing in a randomized controlled trial.