Dendrimers and Derivatives as Multifunctional Nanotherapeutics for Alzheimer's Disease

Comparative efficacy and safety of antidiabetic agents in Alzheimer's disease: A network meta-analysis of randomized controlled trials

BACKGROUND

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with limited treatment options. Emerging evidence suggests that antidiabetic agents may offer neuroprotective effects by targeting shared pathophysiological mechanisms such as insulin resistance and neuroinflammation. However, the comparative efficacy, and safety of these agents in the treatment of AD remain unclear.

OBJECTIVES

This study aimed to systematically evaluate and compare the efficacy and safety of antidiabetic agents for improving cognitive outcomes, reducing amyloid-β (Aβ) deposition, and managing adverse effects in patients with AD, using a network meta-analysis of randomized controlled trials (RCTs).

METHODS

A comprehensive literature search was conducted across multiple databases to identify RCTs examining the effects of antidiabetic agents in patients with AD. The primary outcomes included cognitive performance (e.g., MMSE scores), Aβ deposition (measured via CSF biomarkers), and safety/adverse effects. A network meta-analysis was performed to integrate direct and indirect evidence, ranking interventions using Surface Under the Cumulative Ranking (SUCRA) probabilities. Risk of bias was assessed using the Cochrane risk-of-bias tool.

RESULTS

A total of 26 studies, involving 7,361 participants, were included in the analysis. The interventions evaluated included insulin detemir (both low-dose and high-dose), liraglutide, exenatide, metformin, and pioglitazone. Both low-dose insulin detemir (mean difference: 2.10, 95 % CI: 1.04 to 3.15), high-dose insulin detemir (mean difference: 1.40, 95 % CI: -0.07 to 2.88), exenatide (mean difference: 1.19, 95 % CI: 0.06 to 2.32), and metformin combined with exenatide (mean difference: 1.06, 95 % CI: -1.68 to 3.80) showed cognitive improvements compared to placebo. Among these, low-dose insulin detemir demonstrated the most significant improvement. In terms of reducing Aβ deposition, metformin ranked highest in effectiveness, with the highest SUCRA score (84.6), followed by high-dose insulin detemir (SUCRA: 54.1). Low-dose insulin detemir (SUCRA: 51.1) also demonstrated moderate efficacy. Low-dose insulin detemir showed some reduction in Aβ deposition (mean difference: -0.31, 95 % CI: -2.82 to 2.20), although statistical significance was limited. Liraglutide exhibited the highest rate of study treatment withdrawal (mean difference: 1.97, 95 % CI: -0.07 to 4.00), while pioglitazone demonstrated the lowest withdrawal rates (mean difference: 0.07, 95 % CI: -0.03 to 0.17).

CONCLUSIONS

This network meta-analysis provides valuable insights into the comparative efficacy and safety of antidiabetic agents in AD. Low-dose insulin detemir demonstrated the most significant cognitive improvement and a moderate effect on reducing Aβ deposition. Metformin emerged as the most effective agent for reducing Aβ levels, though its effects on cognitive function were less pronounced. Safety profiles varied, with liraglutide associated with the highest rate of treatment withdrawals, while pioglitazone demonstrated the lowest incidence of treatment-related discontinuations. These findings support the potential use of antidiabetic agents, particularly insulin detemir, as a therapeutic option for AD, although further studies are needed to confirm their long-term benefits and safety.

Nanocarrier-mediated modulation of cGAS-STING signaling pathway to disrupt tumor microenvironment

The cGAS-STING signaling plays an important role in the immune response in a tumor microenvironment (TME) of triple-negative breast cancer (TNBC). The acute and controlled activation of cGAS-STING signaling results in tumor suppression, while chronic activation of cGAS-STING signaling results in immune-suppressive TME that could result in tumor survival. There is a need, therefore, to develop therapeutic strategies for harnessing tumor suppressive effects of cGAS-STING signaling while minimizing the risks associated with chronic activation. Combination therapies and nanocarriers-based delivery of cGAS-STING agonists have emerged as promising strategies in immunotherapy for controlled modulation of cGAS-STING signaling in cancer. These approaches aim to optimize the tumor suppressive effects of the cGAS-STING pathway while minimizing the challenges associated with modulators of cGAS-STING signaling. In the present review, we discuss recent advancements and strategies in combination therapies and nanocarrier-based delivery systems for effectively controlling cGAS-STING signaling in cancer immunotherapy. Further, we emphasized the significance of nanocarrier-based approaches for effective targeting of the cGAS-STING signaling, tackling resistance mechanisms, and overcoming key challenges like immune suppression, tumor heterogeneity, and off-target effects.

Design of reversible cholinesterase inhibitors: Fine-tuning of enzymatic activity by PAMAM-calix-dendrimers

Reversible cholinesterase (ChE) inhibitors are widely used drugs for the therapy of various cognitive and neurodegenerative disorders. The development of a "universal drug" with easily tunable ChE inhibition activity is a relevant interdisciplinary problem. Here we propose for the first time the design of novel "fine-tuned" ChE inhibitors based on dendrimers with a thiacalix[4]arene core (PAMAM-calix-dendrimers). A series of first-generation PAMAM-calix-dendrimers with different terminal fragments were designed and synthesized. The human acetylcholinesterase and butyrylcholinesterase inhibition by PAMAM-calix-dendrimers was confirmed by molecular docking and in vitro studies. PAMAM-calix-dendrimers were found to have IC50 values for acetylcholinesterase and butyrylcholinesterase in the range of 0.076-5400 μM. Relationships between the structure of PAMAM-calix-dendrimers and the ChE inhibitory activity were established. The conformation of the macrocyclic core and the nature of the terminal groups were found to exert a direct impact on the inhibitory activity of dendrimers. We anticipate our study to be a starting point for creation of "universal drug" with tunable ChE inhibitory activity to specific therapeutic targets, and more sophisticated in vivo studies of such systems.

Dendrimers-Novel Therapeutic Approaches for Alzheimer's Disease

Dendrimers are covalently bonded globular nanostructures that may be used in the treatment of Alzheimer's disease (AD). Nowadays, AD therapies are focused on improving cognitive functioning and not causal treatment. However, this may change with the use of dendrimers, which are being investigated as a drug-delivery system or as a drug per se. With their ability to inhibit amyloid formation and their anti-tau properties, they are a promising therapeutic option for AD patients. Studies have shown that dendrimers may inhibit amyloid formation in at least two ways: by blocking fibril growth and by breaking already existing fibrils. Neurofibrillary tangles (NFTs) are abnormal filaments built by tau proteins that can be accumulated in the cell, which leads to the loss of cytoskeletal microtubules and tubulin-associated proteins. Cationic phosphorus dendrimers, with their anti-tau properties, can induce the aggregation of tau into amorphous structures. Drug delivery to mitochondria is difficult due to poor transport across biological barriers, such as the inner mitochondrial membrane, which is highly negatively polarized. Dendrimers may be potential nanocarriers and increase mitochondria targeting. Another considered use of dendrimers in AD treatment is as a drug-delivery system, for example, carbamazepine (CBZ) or tacrine. They can also be used to transport siRNA into neuronal tissue and to carry antioxidants and anti-inflammatory drugs to act protectively on the nervous system.

Self-Assembled Nanocarrier Delivery Systems for Bioactive Compounds

Although bioactive compounds (BCs) have many important functions, their applications are greatly limited due to their own defects. The development of nanocarriers (NCs) technology has gradually overcome the defects of BCs. NCs are equally important as BCs to some extent. Self-assembly (SA) methods to build NCs have many advantages than chemical methods, and SA has significant impact on the structure and function of NCs. However, the relationship among SA mechanism, structure, and function has not been given enough attention. Therefore, from the perspective of bottom-up building mechanism, the concept of SA-structure-function of NCs is emphasized to promote the development of SA-based NCs. First, the conditions and forces for occurring SA are introduced, and then the SA basis and molecular mechanism of protein, polysaccharide, and lipid are summarized. Then, varieties of the structures formed based on SA are introduced in detail. Finally, facing the defects of BCs and how to be well solved by NCs are also elaborated. This review attempts to describe the great significance of constructing artificial NCs to deliver BCs from the aspects of SA-structure-function, so as to promote the development of SA-based NCs and the wide application of BCs.

Lacticaseibacillus paracasei LC86 mitigates age-related muscle wasting and cognitive impairment in SAMP8 mice through gut microbiota modulation and the regulation of serum inflammatory factors

Purpose

Chronic inflammation contributes to the decline in muscle strength and cognitive abilities associated with aging. This study aims to clarify the effects of oral administration of Lacticaseibacillus paracasei LC86 on these age-related declines, as well as its impact on the composition of gut microbiota.

Methods

Senescence-accelerated mouse prone 8 (SAMP8) mice received a 12 week regimen of LC86 (1 × 109 CFU/day). Muscle strength was assessed through forelimb grip strength and four-limb hanging tests. Cognitive function was evaluated through behavioral performance tests, and changes in gut microbiota were analyzed.

Results

Administration of LC86 significantly enhanced muscle strength, demonstrated by increased grip strength and higher glycogen content in the gastrocnemius muscle (p = 0.041, p = 0.017, and p = 0.000, respectively). Behavioral tests suggested that LC86 mitigated age-related cognitive decline. Furthermore, there was a significant decrease in serum pro-inflammatory cytokines, such as IL-6, TNF-α, and MCP-1 (p = 0.002, p = 0.000, and p = 0.005, respectively), and an elevation in the anti-inflammatory cytokine IL-10 level (p = 0.000). An increase in hepatic antioxidant capacity was observed. Significant changes in the gut microbiota composition were noted, including increased populations of Bifidobacterium and Lactobacillus and decreased levels of Escherichia/Shigella and Bacteroides.

Conclusion

The findings suggest that LC86 supplementation mitigates muscle weakness and cognitive impairment in aging SAMP8 mice, potentially through the modulation of inflammation and gut microbiota composition. LC86 emerges as a promising candidate for ameliorating the decline of muscular and cognitive functions associated with aging.

In Vivo Applications of Dendrimers: A Step toward the Future of Nanoparticle-Mediated Therapeutics

Over the last few years, the development of nanotechnology has allowed for the synthesis of many different nanostructures with controlled sizes, shapes, and chemical properties, with dendrimers being the best-characterized of them. In this review, we present a succinct view of the structure and the synthetic procedures used for dendrimer synthesis, as well as the cellular uptake mechanisms used by these nanoparticles to gain access to the cell. In addition, the manuscript reviews the reported in vivo applications of dendrimers as drug carriers for drugs used in the treatment of cancer, neurodegenerative diseases, infections, and ocular diseases. The dendrimer-based formulations that have reached different phases of clinical trials, including safety and pharmacokinetic studies, or as delivery agents for therapeutic compounds are also presented. The continuous development of nanotechnology which makes it possible to produce increasingly sophisticated and complex dendrimers indicates that this fascinating family of nanoparticles has a wide potential in the pharmaceutical industry, especially for applications in drug delivery systems, and that the number of dendrimer-based compounds entering clinical trials will markedly increase during the coming years.

Multistage Self-Assembled Nanomaterials for Cancer Immunotherapy

Advances in nanotechnology have brought innovations to cancer therapy. Nanoparticle-based anticancer drugs have achieved great success from bench to bedside. However, insufficient therapy efficacy due to various physiological barriers in the body remains a key challenge. To overcome these biological barriers and improve the therapeutic efficacy of cancers, multistage self-assembled nanomaterials with advantages of stimuli-responsiveness, programmable delivery, and immune modulations provide great opportunities. In this review, we describe the typical biological barriers for nanomedicines, discuss the recent achievements of multistage self-assembled nanomaterials for stimuli-responsive drug delivery, highlighting the programmable delivery nanomaterials, in situ transformable self-assembled nanomaterials, and immune-reprogramming nanomaterials. Ultimately, we perspective the future opportunities and challenges of multistage self-assembled nanomaterials for cancer immunotherapy.

Molecularly or atomically precise nanostructures for bio-applications: how far have we come?

A huge variety of nanostructures are promising for biomedical applications, but only a few have been practically applied. Among the various reasons, the limited structural preciseness is a critical one, as it increases the difficulty in product quality control, accurate dosing, and ensuring the repeatability of material performance. Constructing nanoparticles with molecule-like preciseness is becoming a new research field. In this review, we focus on the artificial nanomaterials that can currently be molecularly or atomically precise, including DNA nanostructures, some metallic nanoclusters, dendrimer nanoparticles and carbon nanostructures, describing their syntheses, bio-applications and limitations, in view of up-to-date studies. A perspective on their potential for clinical translation is also given. This review is expected to provide a particular rationale for the future design of nanomedicines.

Nanoparticles and cytokine response

Synthetic nanoparticles (NPs) are non-viral equivalents of viral gene delivery systems that are actively explored to deliver a spectrum of nucleic acids for diverse range of therapies. The success of the nanoparticulate delivery systems, in the form of efficacy and safety, depends on various factors related to the physicochemical features of the NPs, as well as their ability to remain "stealth" in the host environment. The initial cytokine response upon exposure to nucleic acid bearing NPs is a critical component of the host response and, unless desired, should be minimized to prevent the unintended consequences of NP administration. In this review article, we will summarize the most recent literature on cytokine responses to nanoparticulate delivery systems and identify the main factors affecting this response. The NP features responsible for eliciting the cytokine response are articulated along with other factors related to the mode of therapeutic administration. For diseases arising from altered cytokine pathophysiology, attempts to silence the individual components of cytokine response are summarized in the context of different diseases, and the roles of NP features on this respect are presented. We finish with the authors' perspective on the possibility of engineering NP systems with controlled cytokine responses. This review is intended to sensitize the reader with important issues related to cytokine elicitation of non-viral NPs and the means of controlling them to design improved interventions in the clinical setting.

Phosphorus-carrying cascade molecules: inner architecture to biomedical applications

Cascade molecules are nearly uniform-sized macromolecules of small molecules or linear polymer cores built around symmetric branching units. A wide range of biological properties can be achieved with phosphorus-containing dendrimers, depending on their terminal functions, ranging from biomaterials to imaging, drug delivery, and acting as a drug by themselves. This feature article presents significant examples of phosphorus-containing dendrimers used to develop biochips, support cell cultures, carry or deliver biomacromolecules and drugs, bioimaging, and combinational benefits. Because of the thermal stability, ferrocene function, and physical and chemical properties of phosphorus, dendrimers show greater rigidity, mobility, and strength. These dendrimers will be discussed as having a favorable effect on cell growths, especially on neuronal cells, as well as human immune cells like natural killer cells and monocytes, which have a crucial part in preventing cancerous and viral infections. Several phosphorus dendrimers are effective as drugs by themselves (drug per se) and show their activity against neurodegenerative diseases, cancer, inflammation, ocular hypertension, and transmissible spongiform encephalopathies (TSEs) in both in vivo and in vitro. The present review discusses the synthetic route, fabrications, and biomedical applications of phosphorus-containing dendrimers. The toxicity of these dendrimers was also reported.