Targeted delivery of acrolein scavenger hydralazine in spinal cord injury using folate-linker-drug conjugation

Acrolein scavengers and detoxification: From high-throughput screening of flavonoids to mechanistic study of epigallocatechin gallate

Acrolein (ACR) is a widespread, highly toxic substance that poses significant health risks. Flavonoids have been recognized as effective ACR scavengers, offering a possible way to reduce these risks. However, the lack of specific high-throughput screening methods has limited the identification of ACR scavengers, and their actual detoxifying capacity on ACR remains unknown. To address this, we developed a high-throughput screening platform to assess the ACR scavenging capacity of 322 flavonoids. Our results showed that 80.7 % of the flavonoids could scavenge ACR, but only 34.4 % exhibited detoxifying effects in an ACR-injured QSG7701 cell model. Some flavonoids even increased toxicity. Structure-activity relationship (SAR) analysis indicated that galloyl and pyrogallol units enhance scavenging but worsen ACR-induced cytotoxicity. Further investigation revealed that epigallocatechin gallate (EGCG) could exacerbate ACR-induced redox disorder, leading to cell apoptosis. Our findings provide crucial data on the scavenging and detoxifying capacities of 322 flavonoids, highlighting that ACR scavengers might not mitigate ACR-induced toxicity and could pose additional safety risks.

Current multi-scale biomaterials for tissue regeneration following spinal cord injury

Spinal cord injury (SCI) may cause loss of motor and sensory function, autonomic dysfunction, and thus disrupt the quality of life of patients, leading to severe disability and significant psychological, social, and economic burden. At present, existing therapy for SCI have limited ability to promote neural function recovery, and there is an urgent need to develop innovative regenerative approaches to repair SCI. Biomaterials have become a promising strategy to promote the regeneration and repair of damaged nerve tissue after SCI. Biomaterials can provide support for nerve tissue by filling cavities, and improve local inflammatory responses and reshape extracellular matrix structures through unique biochemical properties to create the optimal microenvironment at the SCI site, thereby promoting neurogenesis and reconnecting damaged spinal cord tissue. Considering the importance of biomaterials in repairing SCI, this article reviews the latest progress of multi-scale biomaterials in SCI treatment and tissue regeneration, and evaluates the relevant technologies for manufacturing biomaterials.

Acrolein: formation, health hazards and its controlling by dietary polyphenols

Acrolein, a highly reactive toxic aldehyde, is a common dietary and environmental contaminant which can also be generated endogenously. Exposure to acrolein has been positively associated with some pathological conditions, such as atherosclerosis, diabetes mellitus, stroke, and Alzheimer's disease. At the cellular level, acrolein induces various harmful effects, particularly protein adduction and oxidative damages. Polyphenols are a group of secondary plant metabolites ubiquitously presented in fruits, vegetables, and herbs. Recent evidence has gradually solidified the protective role of polyphenols by working as acrolein scavengers and regulator of acrolein toxicities. This was largely attributed to the ability of polyphenols as antioxidants and sacrificial nucleophiles in trapping acrolein. This review discussed the exposure and toxicity of acrolein, summarized the known and anticipated contribution of polyphenols in ameliorating acrolein contamination and its health hazards.

FAP Radioligand Linker Optimization Improves Tumor Dose and Tumor-to-Healthy Organ Ratios in 4T1 Syngeneic Model

Fibroblast activation protein (FAP) has attracted considerable attention as a possible target for the radiotherapy of solid tumors. Unfortunately, initial efforts to treat solid tumors with FAP-targeted radionuclides have yielded only modest clinical responses, suggesting that further improvements in the molecular design of FAP-targeted radiopharmaceutical therapies (RPT) are warranted. In this study, we report several advances on the previously described FAP6 radioligand that increase tumor retention and accelerate healthy tissue clearance. Seven FAP6 derivatives with different linkers or albumin binders were synthesized, radiolabeled, and investigated for their effects on binding and cellular uptake. The radioligands were then characterized in 4T1 tumor-bearing Balb/c mice using both single-photon emission computed tomography (SPECT) and ex vivo biodistribution analyses to identify the conjugate with the best tumor retention and tumor-to-healthy organ ratios. The results reveal an optimized FAP6 radioligand that exhibits efficacy and safety properties that potentially justify its translation into the clinic.

The Role of Vitamins in Spinal Cord Injury: Mechanisms and Benefits

Spinal cord injury (SCI) is a common neurological disease worldwide, often resulting in a substantial decrease in quality of life, disability, and in severe cases, even death. Unfortunately, there is currently no effective treatment for this disease. Nevertheless, current basic and clinical evidence suggests that vitamins, with their antioxidant properties and biological functions, may play a valuable role in improving the quality of life for individuals with SCI. They can promote overall health and facilitate the healing process. In this review, we discuss the mechanisms and therapeutic potential of vitamins in the treatment of SCI.

Neuroprotection by acrolein sequestration through exogenously applied scavengers and endogenous enzymatic enabling strategies in mouse EAE model

We have previously shown that the pro-oxidative aldehyde acrolein is a critical factor in MS pathology. In this study, we found that the acrolein scavenger hydralazine (HZ), when applied from the day of induction, can suppress acrolein and alleviate motor and sensory deficits in a mouse experimental autoimmune encephalomyelitis (EAE) model. Furthermore, we also demonstrated that HZ can alleviate motor deficits when applied after the emergence of MS symptoms, making potential anti-acrolein treatment a more clinically relevant strategy. In addition, HZ can reduce both acrolein and MPO, suggesting a connection between acrolein and inflammation. We also found that in addition to HZ, phenelzine (PZ), a structurally distinct acrolein scavenger, can mitigate motor deficits in EAE when applied from the day of induction. This suggests that the likely chief factor of neuroprotection offered by these two structurally distinct acrolein scavengers in EAE is their common feature of acrolein neutralization. Finally, up-and-down regulation of the function of aldehyde dehydrogenase 2 (ALDH2) in EAE mice using either a pharmacological or genetic strategy led to correspondent motor and sensory changes. This data indicates a potential key role of ALDH2 in influencing acrolein levels, oxidative stress, inflammation, and behavior in EAE. These findings further consolidate the critical role of aldehydes in the pathology of EAE and its mechanisms of regulation. This is expected to reinforce and expand the possible therapeutic targets of anti-aldehyde treatment to achieve neuroprotection through both endogenous and exogenous manners.

In Situ Reaction-Generated Aldehyde-Scavenging Polypeptides-Curcumin Conjugate Nanoassemblies for Combined Treatment of Spinal Cord Injury

The microenvironment after traumatic spinal cord injury (SCI) involves complex pathological processes, including elevated oxidative stress, accumulated reactive aldehydes from lipid peroxidation, excessive immune cell infiltration, etc. Unfortunately, most of current neuroprotection therapies cannot cope with the intricate pathophysiology of SCI, leading to scant treatment efficacies. Here, we developed a facile in situ reaction-induced self-assembly method to prepare aldehyde-scavenging polypeptides (PAH)-curcumin conjugate nanoassemblies (named as PFCN) for combined neuroprotection in SCI. The prepared PFCN could release PAH and curcumin in response to oxidative and acidic SCI microenvironment. Subsequently, PFCN exhibited an effectively neuroprotective effect through scavenging toxic aldehydes as well as reactive nitrogen and oxygen species in neurons, modulating microglial M1/M2 polarization, and down-regulating the expression of inflammation-related cytokines to inhibit neuroinflammation. The intravenous administration of PFCN could significantly ameliorate the malignant microenvironment of injured spinal cord, protect the neurons, and promote the motor function recovery in the contusive SCI rat model.

Tumor-specific activation of folate receptor beta enables reprogramming of immune cells in the tumor microenvironment

Folate receptors can perform folate transport, cell adhesion, and/or transcription factor functions. The beta isoform of the folate receptor (FRβ) has attracted considerable attention as a biomarker for immunosuppressive macrophages and myeloid-derived suppressor cells, however, its role in immunosuppression remains uncharacterized. We demonstrate here that FRβ cannot bind folate on healthy tissue macrophages, but does bind folate after macrophage incubation in anti-inflammatory cytokines or cancer cell-conditioned media. We further show that FRβ becomes functionally active following macrophage infiltration into solid tumors, and we exploit this tumor-induced activation to target a toll-like receptor 7 agonist specifically to immunosuppressive myeloid cells in solid tumors without altering myeloid cells in healthy tissues. We then use single-cell RNA-seq to characterize the changes in gene expression induced by the targeted repolarization of tumor-associated macrophages and finally show that their repolarization not only changes their own phenotype, but also induces a proinflammatory shift in all other immune cells of the same tumor mass, leading to potent suppression of tumor growth. Because this selective reprogramming of tumor myeloid cells is accompanied by no systemic toxicity, we propose that it should constitute a safe method to reprogram the tumor microenvironment.

Acute Transcriptomic and Epigenetic Alterations at T12 After Rat T10 Spinal Cord Contusive Injury

Spinal cord injury is a severely debilitating condition affecting a significant population in the USA. Spinal cord injury patients often have increased risk of developing persistent neuropathic pain and other neurodegenerative conditions beyond the primary lesion center later in their life. The molecular mechanism conferring to the "latent" damages at distal tissues, however, remains elusive. Here, we studied molecular changes conferring abnormal functionality at distal spinal cord (T12) beyond the lesion center (T10) by combining next-generation sequencing (RNA- and bisulfite sequencing), super-resolution microscopy, and immunofluorescence staining at 7 days post injury. We observed significant transcriptomic changes primarily enriched in neuroinflammation and synaptogenesis associated pathways. Transcription factors (TFs) that regulate neurogenesis and neuron plasticity, including Egr1, Klf4, and Myc, are significantly upregulated. Along with global changes in chromatin arrangements and DNA methylation, including 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC), bisulfite sequencing further reveals the involvement of DNA methylation changes in regulating cytokine, growth factor, and ion channel expression. Collectively, our results pave the way towards understanding transcriptomic and epigenomic mechanism in conferring long-term disease risks at distal tissues away from the primary lesion center and shed light on potential molecular targets that govern the regulatory mechanism at distal spinal cord tissues.

Nanostructured steady-state nanocarriers for nutrients preservation and delivery

Food bioactives possess specific physiological benefits of preventing certain diet-related chronic diseases or maintain human health. However, the limitations of the bioactives are their poor stability, lower water solubility and unacceptable bioaccessibility. Structure damage or degradation is often found for the bioactives under certain environmental conditions like high temperature, strong light, extreme pH or high oxygen concentration during food processing, packaging, storage and absorption. Nanostructured steady-state nanocarriers have shown great potential in overcoming the drawbacks for food bioactives. Various delivery systems including solid form delivery system, liquid form delivery system and encapsulation technology have been developed. The embedded food nutrients can largely decrease the loss and degradation during food processing, packaging and storage. The design and application of stimulus and targeted delivery systems can improve the stability, bioavailability and efficacy of the food bioactives upon oral consumption due to enzymatic degradation in the gastrointestinal tract. The food nutrients encapsulated in the smart delivery system can be well protected against degradation during oral administration, thus improving the bioavailability and releazing controlled or targeted release for food nutrients. The encapsulated food bioactives show great potential in nutrition therapy for sub-health status and disease. Much effort is required to design and prepare more biocompatible nanostructured steady-state nanocarriers using food-grade protein or polysaccharides as wall materials, which can be used in food industry and maintain the human health.

Hydralazine plays an immunomodulation role of pro-regeneration in a mouse model of spinal cord injury

Spinal cord injury (SCI) results in severe motor and sensory dysfunction with no effective therapy. Spinal cord debris (sp) from injured spinal cord evokes secondary SCI continuously. We and other researchers have previously clarified that it is mainly bone marrow derived macrophages (BMDMs) infiltrating in the lesion epicenter to clear sp, rather than local microglia. Unfortunately, the pro-inflammatory phenotype of these infiltrating BMDMs is predominant which impairs wound healing. Hydralazine, as a potent vasodilator and scavenger of acrolein, has protective effects in many diseases. Hydralazine is also confirmed to promote motor function and hypersensitivity in SCI rats through scavenging acrolein. However, few studies have explored the effects of hydralazine on immunomodulation, as well as spontaneous pain and emotional response, the important syndromes in clinical patients. It remains unclear whether hydralazine affects infiltrating BMDMs after SCI. In this study, we targeted BMDMs to explore the influence of hydralazine on immune cells in a mouse model of SCI, and also investigated the contribution of polarized BMDMs to hydralazine-induced neurological function recovery after SCI in male mice. The adult male mice underwent T10 spinal cord compression. The results showed that in addition to improving motor function and hypersensitivity, hydralazine relieved SCI-induced spontaneous pain and emotional response, which is a newly discovered function of hydralazine. Hydralazine inhibited the recruitments of pro-inflammatory BMDMs and educated infiltrated BMDMs to a more reparative phenotype involving in multiple biological processes associated with SCI pathology, including immune/inflammation response, neurogenesis, lipid metabolism, oxidative stress, fibrosis formation, and angiogenesis, etc. As an overall effect, hydralazine-treated BMDMs loaden with sp partially rescued neurological function after SCI. It is concluded that hydralazine plays an immunomodulation role of educating pro-inflammatory BMDMs to a more reparative phenotype; and hydralazine-educated BMDMs contribute to hydralazine-induced improvement of neurological function in SCI mice, which provides support for drug and cell treatment options for SCI therapy.

Mass Spectrometry Analysis of DNA and Protein Adducts as Biomarkers in Human Exposure to Cigarette Smoking: Acrolein as an Example

Acrolein is a major component in cigarette smoke and a product of endogenous lipid peroxidation. It is difficult to distinguish human exposure to acrolein from exogenous sources versus endogenous causes, as components in cigarette smoke can stimulate lipid peroxidation in vivo. Therefore, analysis of acrolein-induced DNA and protein adducts by the highly accurate, sensitive, and specific mass spectrometry-based methods is vital to estimate the degree of damage by this IARC Group 2A carcinogen. This Perspective reviews the analyses of acrolein-induced DNA and protein adducts in humans by mass spectrometry focusing on samples accessible for biomonitoring, including DNA from leukocytes and oral cells and abundant proteins from blood, i.e., hemoglobin and serum albumin.