Microglial interaction with beta-amyloid: implications for the pathogenesis of Alzheimer’s disease.

Abstract

“The etiology of Alzheimer’s disease (AD) involves a significant inflammatory component as evidenced by the presence of elevated levels of a diverse range of proinflammatory molecules in the AD brain. These inflammatory molecules are produced principally by activated microglia, which are found to be clustered within and adjacent to the senile plaque. Moreover, long-term treatment of patients with non-steroidal anti-inflammatory drugs has been shown to reduce risk and incidence of AD and delay disease progression. The microglia respond to beta-amyloid (Abeta) deposition in the brain through the interaction of fibrillar forms of amyloid with cell surface receptors, leading to the activation of intracellular signal transduction cascades. The activation of multiple independent signaling pathways ultimately leads to the induction of proinflammatory gene expression and production of reactive oxygen and nitrogen species. These microglial inflammatory products act in concert to produce neuronal toxicity and death. Therapeutic approaches focused on inhibition of the microglial-mediated local inflammatory response in the AD brain offer new opportunities to intervene in the disease.”

http://www.ncbi.nlm.nih.gov/pubmed/11455613

In search of a treatment for Alzheimer’s disease and potential immunonosuppresive therapeutic interventions.

Abstract

“Alzheimer’s disease (AD) is a serious neurodegenerative disease of aging. Recent projections of the dramatic increase in AD incidence worldwide by 2050 reveal its magnitude as a world-wide health crisis and underscore the urgent need to understand the etiology of AD in order to develop therapeutic interventions. A popular debate among scientists has traditionally pitted those in support of Beta amyloid protein as a causative factor (“Baptists”) against others who implicate tau hyperphosphorylation (“Tauists”). Considering the significance of Beta amyloid protein and hyperphosphorlyated tau protein aggregates in AD pathology, this article delves into the nature of inflammation associated with these aggregates. Aspects of inflammation focus on microglia, resident immune cells of the CNS that are activated during AD inflammation and are known to play a significant role in pathogenesis. This article discusses the role of microglia, inflammation, and the immune response as a middle ground in the debate between the “Tauists” and the “Baptists” respective positions. It explores recent advances in immunotherapy and supports continued research in and use of immunosuppressive regimens as potential therapeutic interventions for AD.”

http://www.ncbi.nlm.nih.gov/pubmed/18766151

An amyloid β42-dependent deficit in anandamide mobilization is associated with cognitive dysfunction in Alzheimer’s disease.

“The endocannabinoids and their attending cannabinoid (CB)(1) receptors have been implicated in the control of cognition, but their possible roles in dementias are still unclear.

 The results suggest that an Aβ(42)-dependent impairment in brain anandamide mobilization contributes to cognitive dysfunction in AD.”

http://www.ncbi.nlm.nih.gov/pubmed/21546126

Alzheimer’s disease and Notch signaling.

Abstract

“Cleavage of the amyloid precursor protein (APP) by gamma-secretase generates a neurotoxic amyloid beta-peptide (Abeta) that is thought to be associated with the neurodegeneration observed in Alzheimer’s disease (AD) patients. Presenilin is the catalytic member of the gamma-secretase proteolytic complex and mutations in presenilins are the major cause of early-onset familial Alzheimer’s disease. In addition to APP, gamma-secretase substrates include Notch1 homologues, Notch ligands Delta and Jagged, and additional type I membrane proteins, raising concerns about mechanism-based toxicities that might arise as a consequence of inhibiting gamma-secretase. Notch signaling is involved in tumorigenesis as well as in determining the fates of neural and nonneural cells during development and in adults. Alterations in proteolysis of the Notch by gamma-secretase could be involved in the pathogenesis of AD. Inconsistently, several recent observations have indicated that enhanced Notch signaling and expression could be instrumental in neurodegeneration in AD. Therefore, detailed and precise study of Notch signaling in AD is important for elucidating diverse mechanisms of pathogenesis and potentially for treating and preventing Alzheimer’s disease.”

http://www.ncbi.nlm.nih.gov/pubmed/19853579

The endocannabinoid, anandamide, augments Notch-1 signaling in cultured cortical neurons exposed to amyloid-β and in the cortex of aged rats.

“Aberrant Notch signaling has recently emerged as a possible mechanism for the altered neurogenesis, cognitive impairment, and learning and memory deficits associated with Alzheimer disease (AD). Recently, targeting the endocannabinoid system in models of AD has emerged as a potential approach to slow the progression of the disease process. Although studies have identified neuroprotective roles for endocannabinoids, there is a paucity of information on modulation of the pro-survival Notch pathway by endocannabinoids. In this study the influence of the endocannabinoids, anandamide (AEA) and 2-arachidonoylglycerol, on the Notch-1 pathway and on its endogenous regulators were investigated in an in vitro model of AD. We report that AEA up-regulates Notch-1 signaling in cultured neurons… In summary, AEA has the proclivity to enhance Notch-1 signaling in an in vitro model of AD, which may have relevance for restoring neurogenesis and cognition in AD.”

http://www.ncbi.nlm.nih.gov/pubmed/22891244

Role of the endocannabinoid system in Alzheimer’s disease: new perspectives.

Abstract

“The role of the endocannabinoid system in several diseases is currently under intense study. Among these, Alzheimer’s disease may be a new promising area of research. We have recently reported the existence of profound changes in the location and density of several elements of this system in Alzheimer’s disease tissue samples, indicating that a non-neuronal endocannabinoid system is up-regulated in activated glia. Additional data from other groups suggest that glial cells may be important elements in the regulation of endocannabinoid system activity, both in health as in disease. Some of these aspects are briefly discussed in the present review.”

http://www.ncbi.nlm.nih.gov/pubmed/15306158

Cannabis and Alzheimer’s disease

“‘Clearly in the test tube cannabinoids have the ability to block at least one of the probable causal mechanisms in Alzheimer’s disease and so become a potential treatment or preventative agent that needs to be tested in humans.”

Dr Richard Harvey, research director of the Alzheimer’s Society

Read more: http://www.alzheimers.org.uk/site/scripts/news_article.php?newsID=123

Cannabis May Cut Alzheimer’s Risk – Discovery News

“For those who have inhaled, there may be some good news: Marijuana use may cut the risk of developing Alzheimer’s disease by reducing inflammation in the brain…

The findings may explain studies showing those who regularly used marijuana in the 1960s and 1970s are now less likely to develop Alzheimer’s disease than their non-smoking contemporaries.

Under a National Institutes of Health grant, researchers used a synthetic drug similar to marijuana to treat rats with brain inflammation typically associated with Alzheimer’s disease, a form of dementia that afflicts 4.5 million people in the United States alone.”

Read more: http://dsc.discovery.com/news/2006/10/19/marijuana_hea.html

Marijuana Ingredient May Help Alzheimer’s – WebMD

“Chemical Counters Brain Problems in Alzheimer’s Disease, Says Spanish Study.
New clues about Alzheimer’s disease have emerged from a Spanish study of marijuana. The drug’s active ingredients — cannabinoids — help prevent brain problems seen in Alzheimer’s, say the scientists.

The findings showed that “cannabinoids work both to prevent inflammation and to protect the brain,” says researcher Maria de Ceballos in a news release. That “may set the stage for [cannabinoids’] use as a therapeutic approach for [Alzheimer’s disease].”

The cannabinoids completely prevented activation of cells that trigger inflammation. These cells gather near plaque and are believed to be involved in the development of Alzheimer’s disease.

“Our results indicate that cannabinoid receptors are important in the pathology of Alzheimer’s disease and that cannabinoids succeed in preventing the neurodegenerative process occurring in the disease,” write the researchers in the journal.”

Read more: http://www.webmd.com/alzheimers/news/20050223/marijuana-ingredient-may-help-alzheimers

Marijuana May Slow Alzheimer’s – WebMD

“Key Marijuana Compound Beats Current Alzheimer’s Drugs in Test-Tube Study.
THC, the key compound in marijuana, may also be the key to new drugs for Alzheimer’s disease.”While we are certainly not advocating the use of illegal drugs, these findings offer convincing evidence that THC possesses remarkable inhibitory qualities, especially when compared to [Alzheimer’s drugs] currently available to patients,” Janda says in a news release.

“Although our study is far from final, it does show that there is a previously unrecognized molecular mechanism through which THC may directly affect the progression of Alzheimer’s disease.”

“THC and its analogs may provide an improved [treatment for] both the symptoms and progression of Alzheimer’s disease,” the researchers conclude”

Read more: http://www.webmd.com/alzheimers/news/20061006/marijuana-may-slow-alzheimers