Anti-diabetic and neuroprotective effects of pancreatic islet transplantation into the central nervous system

Differentially expressed long non-coding RNAs and mRNAs of cadmium exposure on learning disability of offspring rats

BACKGROUND

Cadmium (Cd) exposure has been found to have detrimental effects on the development of the central nervous system and cognitive ability in children. However, there is ongoing debate regarding the impact of maternal Cd exposure on the cognitive ability of offspring. In this study, we aimed to investigate the mechanisms underlying the influence of maternal Cd exposure on the cognitive ability of offspring rats.

METHODS

Here, we constructed a model of cadmium poisoning in first-generation rats through gavage. The cognitive and memory abilities of its offspring were evaluated by water maze experiment. Then, we used the gene chip to find out the key genes, and we performed qRT-PCR detection of these genes. Subsequently, enrichment analysis was employed to identify pathways. Finally, we constructed a co-expression network consisting of LncRNAs and mRNAs to elucidate the biological functions and regulatory mechanisms of LncRNAs.

RESULTS

The results of the water maze trial demonstrated that the offspring of rats exposed to cadmium in the first generation had reduced cognitive and memory abilities. Through an analysis of gene expression in the hippocampus of the cadmium-treated rats' offspring and the control group, we identified a correlation between the islet secretion pathway and the cognitive impairment observed in the offspring. Utilizing various algorithms, we identified Cpa1 and Prss1 as potential key genes associated with the cognitive impairment caused by cadmium. The results of qRT-PCR demonstrated a decrease in the expression levels of these genes in the hippocampus of the cadmium-treated rats' offspring. In addition, in the co-expression network, we observed that Cpa1 was co-expressed with 11 LncRNAs, while Prss1 was associated with 4 unexplored LncRNAs. Furthermore, we conducted an analysis to examine the relationship between Cpa1, Prss1-related transcription factors, and LncRNAs.

CONCLUSION

Overall, this study provides novel insights into the molecular effects of first generation Cd exposure on the cognitive ability of offspring. The target genes and signaling pathways investigated in this study could serve as potential targets for improving neurodevelopment and cognitive ability in children.

Targets and mechanisms of dietary anthocyanins to combat hyperglycemia and hyperuricemia: a comprehensive review

Hyperglycemia and hyperuricemia are both metabolic disorders related to excessive amount of metabolites in blood, which are considered as high risk factors for the development of many chronic diseases. Enzymes, cells, tissues and organs, which are relevant to metabolism and excretion of glucose and UA, are usually regarded to be the targets in treatment of hyperglycemia and hyperuricemia. Several drugs have been commonly applied to combat hyperglycemia and hyperuricemia through various targets but with unignorable side effects. Anthocyanins have become promising alternatives against hyperglycemia and hyperuricemia because of their bio-activities with little side effects. Structurally different anthocyanins from berry fruits, cherries and purple sweet potato lead to the diverse functional activity and property. This review is aimed to illustrate the specific targets that are available for anthocyanins from berry fruits, cherries and purple sweet potato in hyperglycemia and hyperuricemia management, as well as discuss the structure-activity relationship, and the underlying mechanisms associated with intracellular signaling pathway, anti-oxidative stress and anti-inflammation. In addition, the relationship of hyperglycemia and hyperuricemia, and the possibly regulative role of anthocyanins against them, along with the effects of anthocyanins in clinical trial are mentioned.

Engineering the vasculature for islet transplantation

The microvasculature in the pancreatic islet is highly specialized for glucose sensing and insulin secretion. Although pancreatic islet transplantation is a potentially life-changing treatment for patients with insulin-dependent diabetes, a lack of blood perfusion reduces viability and function of newly transplanted tissues. Functional vasculature around an implant is not only necessary for the supply of oxygen and nutrients but also required for rapid insulin release kinetics and removal of metabolic waste. Inadequate vascularization is particularly a challenge in islet encapsulation. Selectively permeable membranes increase the barrier to diffusion and often elicit a foreign body reaction including a fibrotic capsule that is not well vascularized. Therefore, approaches that aid in the rapid formation of a mature and robust vasculature in close proximity to the transplanted cells are crucial for successful islet transplantation or other cellular therapies. In this paper, we review various strategies to engineer vasculature for islet transplantation. We consider properties of materials (both synthetic and naturally derived), prevascularization, local release of proangiogenic factors, and co-transplantation of vascular cells that have all been harnessed to increase vasculature. We then discuss the various other challenges in engineering mature, long-term functional and clinically viable vasculature as well as some emerging technologies developed to address them. The benefits of physiological glucose control for patients and the healthcare system demand vigorous pursuit of solutions to cell transplant challenges. STATEMENT OF SIGNIFICANCE: Insulin-dependent diabetes affects more than 1.25 million people in the United States alone. Pancreatic islets secrete insulin and other endocrine hormones that control glucose to normal levels. During preparation for transplantation, the specialized islet blood vessel supply is lost. Furthermore, in the case of cell encapsulation, cells are protected within a device, further limiting delivery of nutrients and absorption of hormones. To overcome these issues, this review considers methods to rapidly vascularize sites and implants through material properties, pre-vascularization, delivery of growth factors, or co-transplantation of vessel supporting cells. Other challenges and emerging technologies are also discussed. Proper vascular growth is a significant component of successful islet transplantation, a treatment that can provide life-changing benefits to patients.

Intracranial Transplantation of Pancreatic Islets Attenuates Cognitive and Peripheral Metabolic Dysfunctions in a Rat Model of Sporadic Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) is often associated with brain insulin resistance and peripheral metabolic dysfunctions. Recently, we developed a model of sporadic AD associated with obesity-related peripheral metabolic abnormalities in Lewis rats using intracerebroventricular administration of streptozotocin (icv-STZ).

OBJECTIVE

We aimed to assess the effect of intracranially grafted pancreatic islets on cognitive and peripheral metabolic dysfunctions in the icv-STZ Lewis rats.

METHODS

AD-like dementia associated with obesity was induced in inbred Lewis rats using a single icv-STZ. Two months after icv-STZ, syngeneic islets (100 islets per recipient) were implanted in the cranial subarachnoid cavity of icv-STZ rats. Morris water maze and marble burying tests were used for studying cognitive and behavioral functions. Central and peripheral metabolic alterations were assessed by histological and biochemical assays.

RESULTS

The icv-STZ induced increases in food intake, body weight, and blood levels of insulin and leptin without alteration of glucose homeostasis. Grafted islets reduced body weight gain, food consumption, peripheral insulin resistance, and hyperleptinemia. Biochemical and histological analysis of the brain revealed viable grafted islets expressing insulin and glucagon. The grafted islets did not affect expression of brain insulin receptors and peripheral glucose homeostasis. Two months after islet transplantation, cognitive and behavioral functioning in transplanted rats were significantly better than the sham-operated icv-STZ rats. No significant differences in the locomotor activity between transplanted and non-transplanted icv-STZ rats were found.

CONCLUSIONS

Intracranial islet transplantation attenuates cognitive decline and peripheral metabolic dysfunctions providing a novel therapeutic approach for sporadic AD associated with peripheral metabolic dysfunctions.

The role of short-chain fatty acids in microbiota-gut-brain communication

Short-chain fatty acids (SCFAs), the main metabolites produced by bacterial fermentation of dietary fibre in the gastrointestinal tract, are speculated to have a key role in microbiota-gut-brain crosstalk. However, the pathways through which SCFAs might influence psychological functioning, including affective and cognitive processes and their neural basis, have not been fully elucidated. Furthermore, research directly exploring the role of SCFAs as potential mediators of the effects of microbiota-targeted interventions on affective and cognitive functioning is sparse, especially in humans. This Review summarizes existing knowledge on the potential of SCFAs to directly or indirectly mediate microbiota-gut-brain interactions. The effects of SCFAs on cellular systems and their interaction with gut-brain signalling pathways including immune, endocrine, neural and humoral routes are described. The effects of microbiota-targeted interventions such as prebiotics, probiotics and diet on psychological functioning and the putative mediating role of SCFA signalling will also be discussed, as well as the relationship between SCFAs and psychobiological processes. Finally, future directions to facilitate direct investigation of the effect of SCFAs on psychological functioning are outlined.

The anti-hyperglycemia effects of Rhizoma Coptidis alkaloids: A systematic review of modern pharmacological studies of the traditional herbal medicine

Hyperglycemia is a common endocrine system disease, which seriously affects people's health with a increasing morbidity in recent years. Rhizoma Coptidis (RC), one of the most commonly used traditional Chinese medicines, has been applied to treat diabetes in clinic for thousands of years. Since scientists demonstrated that alkaloids from RC owned the amazing anti-hyperglycemia activities 30 years ago, these compounds have been widely used for the treatment of diabetes and hyperglycemia with unconspicuous toxicities and side effects. With the help of molecular biology, immunology and other techniques, the mechanisms about anti-hyperglycemia effect of RC alkaloids have been extensively discussed. Numerous studies showed that RC alkaloids balanced the glucose homeostasis not only by widely recognizing insulin resistance pathways, but also by promoting insulin secretion, regulating intestinal hormones, ameliorating gut microbiota structures and many other ways. In this review, we combine the latest advances and systematically summarize the mechanisms of RC alkaloids in treating hyperglycemia and diabetic nephropathy to provide a deeper understanding of these natural alkaloids. In addition, the important role of gut microbiota associated with the glucose metabolism is also reviewed.

Selection of Implantation Sites for Transplantation of Encapsulated Pancreatic Islets

Pancreatic islet transplantation has been validated as a valuable therapy for type 1 diabetes mellitus patients with exhausted insulin treatment. However, this therapy remains limited by the shortage of donor and the requirement of lifelong immunosuppression. Islet encapsulation, as an available bioartificial pancreas (BAP), represents a promising approach to enable protecting islet grafts without or with minimal immunosuppression and possibly expanding the donor pool. To develop a clinically implantable BAP, some key aspects need to be taken into account: encapsulation material, capsule design, and implant site. Among them, the implant site exerts an important influence on the engraftment, stability, and biocompatibility of implanted BAP. Currently, an optimal site for encapsulated islet transplantation may include sufficient capacity to host large graft volumes, portal drainage, ease of access using safe and reproducible procedure, adequate blood/oxygen supply, minimal immune/inflammatory reaction, pliable for noninvasive imaging and biopsy, and potential of local microenvironment manipulation or bioengineering. Varying degrees of success have been confirmed with the utilization of liver or extrahepatic sites in an experimental or preclinical setting. However, the ideal implant site remains to be further engineered or selected for the widespread application of encapsulated islet transplantation.