Development of anti-PEG IgG/IgM/IgE ELISA assays for profiling anti-PEG immunoglobulin response in PEG-sensitized individuals and patients with alpha-gal allergy

Innovative gene delivery systems for retinal disease therapy

The human retina, a complex and highly specialized structure, includes multiple cell types that work synergistically to generate and transmit visual signals. However, genetic predisposition or age-related degeneration can lead to retinal damage that severely impairs vision or causes blindness. Treatment options for retinal diseases are limited, and there is an urgent need for innovative therapeutic strategies. Cell and gene therapies are promising because of the efficacy of delivery systems that transport therapeutic genes to targeted retinal cells. Gene delivery systems hold great promise for treating retinal diseases by enabling the targeted delivery of therapeutic genes to affected cells or by converting endogenous cells into functional ones to facilitate nerve regeneration, potentially restoring vision. This review focuses on two principal categories of gene delivery vectors used in the treatment of retinal diseases: viral and non-viral systems. Viral vectors, including lentiviruses and adeno-associated viruses, exploit the innate ability of viruses to infiltrate cells, which is followed by the introduction of therapeutic genetic material into target cells for gene correction. Lentiviruses can accommodate exogenous genes up to 8 kb in length, but their mechanism of integration into the host genome presents insertion mutation risks. Conversely, adeno-associated viruses are safer, as they exist as episomes in the nucleus, yet their limited packaging capacity constrains their application to a narrower spectrum of diseases, which necessitates the exploration of alternative delivery methods. In parallel, progress has also occurred in the development of novel non-viral delivery systems, particularly those based on liposomal technology. Manipulation of the ratios of hydrophilic and hydrophobic molecules within liposomes and the development of new lipid formulations have led to the creation of advanced non-viral vectors. These innovative systems include solid lipid nanoparticles, polymer nanoparticles, dendrimers, polymeric micelles, and polymeric nanoparticles. Compared with their viral counterparts, non-viral delivery systems offer markedly enhanced loading capacities that enable the direct delivery of nucleic acids, mRNA, or protein molecules into cells. This bypasses the need for DNA transcription and processing, which significantly enhances therapeutic efficiency. Nevertheless, the immunogenic potential and accumulation toxicity associated with non-viral particulate systems necessitates continued optimization to reduce adverse effects in vivo . This review explores the various delivery systems for retinal therapies and retinal nerve regeneration, and details the characteristics, advantages, limitations, and clinical applications of each vector type. By systematically outlining these factors, our goal is to guide the selection of the optimal delivery tool for a specific retinal disease, which will enhance treatment efficacy and improve patient outcomes while paving the way for more effective and targeted therapeutic interventions.

Expression and predictive value of serum core fucosylated low molecular weight kininogen and alpha-galactosylated antibodies in patients with hepatic fibrosis

OBJECTIVES

Hepatic fibrosis is a common pathological basis for many chronic liver diseases and can progress to cirrhosis, a leading cause of mortality in liver diseases. Early identification and reversal of hepatic fibrosis are key in the treatment of chronic liver disease. This study aims to compare the expression levels of serum core fucosylated low molecular weight kininogen (LMWK-Fc) and alpha-galactosylated (α-Gal) antibodies in patients with hepatic fibrosis at different stages, and to evaluate their diagnostic efficacy for hepatic fibrosis.

METHODS

A retrospective analysis was conducted on 275 patients with chronic liver disease who visited the Department of Infectious Diseases at the Second Xiangya Hospital of Central South University between June 2022 and March 2023. Among these, 115 patients underwent liver biopsy. Based on the extent of collagen deposition and its impact on liver structure and microcirculation, patients were staged from 0 to 4: S0 (no significant collagen deposition in liver tissues; liver structure and microcirculation are normal), S1 (mild collagen deposition in liver tissues, with partial disruption of lobule structure, but microcirculation remains largely normal), S2 (moderate collagen deposition in liver tissues, with partial disruption of lobule structure and microcirculation), S3 (extensive collagen deposition in liver tissues, with substantial disruption of lobule structure and microcirculation), and S4 (development of cirrhosis, with heavy collagen deposition, complete disruption of lobule structure, and severe impairment of microcirculation). Patients were grouped as no fibrosis (S0), fibrosis (S1-S2), and significant fibrosis (S3-S4). For the 160 patients without liver biopsy, they were categorized based on liver stiffness measurement (LSM) value: no fibrosis (F0: LSM<7.3 kPa), fibrosis (F1-F2: LSM 7.3-12.4 kPa), and significant fibrosis (F3-F4: LSM>12.4 kPa). Demographic data (age, gender) and laboratory indicators (alanine transaminase, aspartate transaminase, gamma-glutamyl transferase, alkaline phosphatase, alpha-fetoprotein, platelet count) were collected to calculate the fibrosis-4 index (FIB-4) and aspartate aminotransferase-to-platelet ratio index (APRI). Serum LMWK-Fc and α-Gal antibodies were measured and compared across the groups, and their correlation with fibrosis severity was analyzed. The receiver operating characteristic (ROC) curve was used to assess the predictive value of serum LMWK-Fc and α-Gal antibody levels for hepatic fibrosis.

RESULTS

Among the 160 patients without complete liver biopsy, serum α-Gal antibody and LMWK-Fc levels increased progressively from the no fibrosis group to the significant fibrosis group, with statistically significant differences (P<0.05). Among the 115 patients with liver biopsy, serum LMWK-Fc levels were significantly higher in the fibrosis group and the significant fibrosis groups compared with the no fibrosis group, and α-Gal antibody levels were significantly higher in the significant fibrosis group compared with the no fibrosis group and the fibrosis group (P<0.001, P=0.032, respectively). Univariate and multivariate linear regression analyses showed that hepatic fibrosis was correlated with gender and LMWK-Fc levels (both P<0.05), but not with age, α-Gal antibody levels, FIB-4, or APRI (all P>0.05).

CONCLUSIONS

The expression levels of serum LMWK-Fc and α-Gal antibodies vary across different stages of hepatic fibrosis, suggesting a potential association with fibrosis progression. LMWK-Fc levels have a certain predictive value for the diagnosis of hepatic fibrosis.

Optimized Enzyme-Linked Immunosorbent Assay for Anti-PEG Antibody Detection in Healthy Donors and Patients Treated with PEGylated Liposomal Doxorubicin

There is considerable interest in quantifying anti-PEG antibodies, given their potential involvement in accelerated clearance, complement activation, neutralization, and acute reactions associated with drug delivery systems. Published and commercially available anti-PEG enzyme-linked immunosorbent assays (ELISAs) differ significantly in terms of reagents and conditions, which could be confusing to users who want to perform in-house measurements. Here, we optimize the ELISA protocol for specific detection of anti-PEG IgG and IgM in sera from healthy donors and in plasma from cancer patients administered with PEGylated liposomal doxorubicin. The criterion of specificity is the ability of free PEG or PEGylated liposomes to inhibit the ELISA signals. We found that coating high-binding plates with monoamine methoxy-PEG5000, as opposed to bovine serum albumin-PEG20000, and blocking with 1% milk, as opposed to albumin or lysozyme, significantly improve the specificity, with over 95% of the signal being blocked by competition. Despite inherent between-assay variability, setting the cutoff value of the optical density at the 80th percentile consistently identified the same subjects. Using the optimized assay, we longitudinally measured levels of anti-PEG IgG/IgM in cancer patients before and after the PEGylated liposomal doxorubicin chemotherapy cycle (1 month apart, three cycles total). Antibody titers did not show any increase but rather a decrease between treatment cycles, and up to 90% of antibodies was bound to the infused drug. This report is a step toward harmonizing anti-PEG assays in human subjects, emphasizing the cost-effectiveness and optimized specificity.

Free PEG Suppresses Anaphylaxis to PEGylated Nanomedicine in Swine

Covalent conjugation of poly(ethylene glycol) (PEG) is frequently employed to enhance the pharmacokinetics and biodistribution of various protein and nanoparticle therapeutics. Unfortunately, some PEGylated drugs can induce elevated levels of antibodies that can bind PEG, i.e., anti-PEG antibodies (APA), in some patients. APA in turn can reduce the efficacy and increase the risks of allergic reactions, including anaphylaxis. There is currently no intervention available in the clinic that specifically mitigates allergic reactions to PEGylated drugs without the use of broad immunosuppression. We previously showed that infusion of high molecular weight free PEG could safely and effectively suppress the induction of APA in mice and restore prolonged circulation of various PEGylated therapeutics. Here, we explored the effectiveness of free PEG as a prophylaxis against anaphylaxis induced by PEG-specific allergic reactions in swine. Injection of PEG-liposomes (PL) resulted in anaphylactoid shock (pseudoanaphylaxis) within 1-3 min in both naïve and PL-sensitized swine. In contrast, repeated injection of free PEG alone did not result in allergic reactions, and injection of free PEG effectively suppressed allergic reactions to PL, including in previously PL-sensitized swine. These results strongly support the further investigation of free PEG for reducing APA and allergic responses to PEGylated therapeutics.