Plasma levels of adipokines in patients with Alzheimer's disease - where is the "breaking point" in Alzheimer's disease pathogenesis?

The role of adiponectin in Alzheimer's disease: A translational review

Adiponectin is an adipokine playing a central role in the regulation of energy homeostasis, carbohydrate and lipid metabolism, as well as immunomodulation. The relationship between Alzheimer's disease (AD) and body composition has highlighted the bidirectional crosstalk between AD's pathophysiology and metabolic disorders. This review aimed to report the current state of knowledge about cellular and molecular mechanisms linking adiponectin and AD, in preclinical studies. Then, we reviewed human studies to assess the relationship between adiponectin levels and AD diagnosis. We also examined the risk of incident AD regarding the participants' baseline adiponectin level, as well as the relationship of adiponectin and cognitive decline in patients with AD. We conducted a systematic review, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses reporting guideline, of studies published over the last decade on MEDLINE and Cochrane databases. Overall, we reviewed 34 original works about adiponectin in AD, including 11 preclinical studies, two both preclinical and human studies and 21 human studies. Preclinical studies brought convincing evidence for the neuroprotective role of adiponectin on several key mechanisms of AD. Human studies showed conflicting results regarding the relationship between AD and adiponectin levels, as well as regarding the cross-sectional association between cognitive function and adiponectin levels. Adiponectin did not appear as a predictor of incident AD, nor as a predictor of cognitive decline in patients with AD. Despite solid preclinical evidence suggesting the protective role of adiponectin in AD, inconsistent results in humans supports the need for further research.

Adipsin – summing up large-scale results: A review

Adipsin is one of the first discovered adipokines hormones produced by adipose tissue. Adipsin performs the function of a regulator of carbohydrate and lipid metabolism and participates in the adaptation of metabolism to the real needs of the body, being a powerful stimulant of anabolic processes. A characteristic feature of adipsin is that it is also a complement factor D, which is necessary for the normal functioning of an alternative pathway of activation of the complement system. Due to this, adipsin is represented in the body as a link between the energy block of the endocrine system and the humoral block of the immune system. Adipsin is known as a regulator of the function of pancreatic beta cells, a stimulator of lipogenesis, a modulator of inflammation processes. Recently, there have been works indicating the effect of adipsin on the microbiota, as well as its role in non-alcoholic fatty liver disease. To date, there are a large number of publications describing the biochemical structure, functions of adipsin, mechanisms of regulation of its synthesis, as well as changes in the level of adipsin in various pathological conditions. Attempts are also described to pharmacologically influence adipsin in order to modulate its functions or use it as a biomarker for the diagnosis of diseases. However, there is currently no structured review that summarizes and systematizes all available information about this adipokine. This is exactly the task we set ourselves in this study. The paper contains the results of all available studies on adipsin. In some cases, they are contradictory in nature, which indicates the need for further research in detecting connections between the body's systems.