Comprehensive Impurity Profiling of mRNA: Evaluating Current Technologies and Advanced Analytical Techniques

In vitro transcription (IVT) of mRNA is a versatile platform for a broad range of biotechnological applications. Its rapid, scalable, and cost-effective production makes it a compelling choice for the development of mRNA-based cancer therapies and vaccines against infectious diseases. The impurities generated during mRNA production can potentially impact the safety and efficacy of mRNA therapeutics, but their structural complexity has not been investigated in detail yet. This study pioneers a comprehensive profiling of IVT mRNA impurities, integrating current technologies with innovative analytical tools. We have developed highly reproducible, efficient, and stability-indicating ion-pair reversed-phase liquid chromatography and capillary gel electrophoresis methods to determine the purity of mRNA from different suppliers. Furthermore, we introduced the applicability of microcapillary electrophoresis for high-throughput (<1.5 min analysis time per sample) mRNA impurity profiling. Our findings revealed that impurities are mainly attributed to mRNA variants with different poly(A) tail lengths due to aborted additions or partial hydrolysis and the presence of double-stranded mRNA (dsRNA) byproducts, particularly the dsRNA 3'-loop back form. We also implemented mass photometry and native mass spectrometry for the characterization of mRNA and its related product impurities. Mass photometry enabled the determination of the number of nucleotides of different mRNAs with high accuracy as well as the detection of their size variants [i.e., aggregates and partial and/or total absence of the poly(A) tail], thus providing valuable information on mRNA identity and integrity. In addition, native mass spectrometry provided insights into mRNA intact mass, heterogeneity, and important sequence features such as poly(A) tail length and distribution. This study highlights the existing bottlenecks and opportunities for improvement in the analytical characterization of IVT mRNA, thus contributing to the refinement and streamlining of mRNA production, paving the way for continued advancements in biotechnological applications.

Discovery adductomics provides a comprehensive portrait of tissue-, age- and sex-specific DNA modifications in rodents and humans

DNA damage causes genomic instability underlying many diseases, with traditional analytical approaches providing minimal insight into the spectrum of DNA lesions in vivo. Here we used untargeted chromatography-coupled tandem mass spectrometry-based adductomics (LC-MS/MS) to begin to define the landscape of DNA modifications in rat and human tissues. A basis set of 114 putative DNA adducts was identified in heart, liver, brain, and kidney in 1-26-month-old rats and 111 in human heart and brain by 'stepped MRM' LC-MS/MS. Subsequent targeted analysis of these species revealed species-, tissue-, age- and sex-biases. Structural characterization of 10 selected adductomic signals as known DNA modifications validated the method and established confidence in the DNA origins of the signals. Along with strong tissue biases, we observed significant age-dependence for 36 adducts, including N2-CMdG, 5-HMdC and 8-Oxo-dG in rats and 1,N6-ϵdA in human heart, as well as sex biases for 67 adducts in rat tissues. These results demonstrate the potential of adductomics for discovering the true spectrum of disease-driving DNA adducts. Our dataset of 114 putative adducts serves as a resource for characterizing dozens of new forms of DNA damage, defining mechanisms of their formation and repair, and developing them as biomarkers of aging and disease.

Comprehensive Analysis of Photoreceptor Outer Segments: Flow Cytometry Characterization and Stress-Driven Impact on Retinal Pigment Epithelium Phagocytosis

Phagocytosis is one of the key functions of retinal pigment epithelium (RPE) cells, which maintain photoreceptor health by removing photoreceptor outer segments (POSs) that are regularly shed. A deficiency in RPE function to phagocytose POSs may lead to vision loss in inherited retinal diseases and eventually to age-related macular degeneration (AMD) with geographic atrophy. Significant progress has been made in the field of cell replacement therapy for AMD using stem-cell-derived RPE. To test their function, RPE cells are incubated with purified bovine POSs for the demonstration of efficient binding, internalization, and digestion of POSs. Here, we present an image-based method to measure phagocytosis activity by using POSs labeled with a pH-sensitive fluorescent dye, which has low fluorescence at neutral pH outside of the cell and high fluorescence at low pH inside the phagosome. Further, we introduce a unique flow-cytometry-based method for the characterization of POSs by measuring specific markers for POSs such as rhodopsin and opsin. Using this method, we demonstrated a comparable quality of several bovine POS isolation batches and a reliable assessment of POS quality on RPE phagocytosis assay performance when subjected to different stress conditions. This work provides new tools to characterize POSs and insight into RPE phagocytosis assay development for the functional evaluation of RPE cells in the field of cell replacement therapy.

Plasma Levels of Free NƐ-Carboxymethyllysine (CML) after Different Oral Doses of CML in Rats and after the Intake of Different Breakfasts in Humans: Postprandial Plasma Level of sRAGE in Humans

N-carboxymethyl-lysine (CML) and other dietary advanced glycation end-products (AGEs) are chemically modified amino acids with potential toxicological effects putatively related to their affinity with the receptor for AGEs (RAGE). The goal of this study was to determine the postprandial kinetics of CML in both rodents and humans and, in the latter, to evaluate their relationship with the soluble RAGE isoforms (sRAGE). Four gavage solutions containing different forms of CML were given to rats, and blood was collected over 8 h. Three different breakfasts containing dietary CML (dCML) were administered to 20 healthy volunteers, and blood was collected over 2 h. Concentrations of CML, CEL, and lysine were quantified in plasma and human meals by LC-MS/MS, and sRAGE was determined in human plasma by ELISA. The results showed that dCML did not affect the concentrations of circulating protein-bound CML and that only free CML increased in plasma, with a postprandial peak at 90 to 120 min. In humans, the postprandial plasmatic sRAGE concentration decreased independently of the dAGE content of the breakfasts. This study confirms reports of the inverse postprandial relationship between plasmatic free CML and sRAGE, though this requires further investigation for causality to be established.

[Aging: a global, multidimensional and preventive approach]

Aging is physiological and begins very early. It can be accelerated by our lifestyle and by chronic diseases. There are over 300 "theories" of aging and many animal models have been developed ranging from yeast to more complex organisms. Civil age is not a reflection of an individual's physiological age. Starting from the age of 30 a decrease in organ function can be observed. The aging of an individual leads him to 3 states: vigourous, polypathological and dependent or frail. The state of fragility is reversible. We have to be an actor in our aging and no longer suffer it. The centenarians of the blue zones have achieved, culturally, active aging which has led them to successful aging.

Circulating biomarkers characterizing physical frailty: CRP, hemoglobin, albumin, 25OHD and free testosterone as best biomarkers. Results of a meta-analysis

INTRODUCTION

During aging, individuals can be classified as being in one of 3 different states: robust, frail or dependent. Frailty is described as reversible, so early detection offers the potential of returning the subject to a robust status. There are multiple clinical frailty scales but no gold standard and frailty is not systematically assessed in clinicians' daily practice. Reliable biomarkers of frailty are lacking, however, while their identification and systematic use would make this simple scale a useful clinical tool.

OBJECTIVE

To conduct a review of the literature concerning the biomarkers associated with frailty and to compare in a meta-analysis the plasmatic values of each biomarker in the frail with the robust group.

RESULTS

503 articles were identified on PubMed, 467 on Scopus and 369 on Web Of Science. 67 articles were included, collecting a total of 32,934 robust subjects and 6864 frail subjects. C-reactive protein (CRP) (Standardized Mean Difference (SMD): 0.49 CI 95% [0.37-0.61]) was significantly higher in the frail group whereas hemoglobin (SMD: -0.67[-0.90; -0.44]), albumin (SMD: -0.62[-0.84; -0.41]), 25-hydroxyvitamin D (25OHD) (SMD: -0.43 [-0.64; -0.21]) and, in men, free testosterone (SMD: -0.77 [-1.05; -0.49]) were significantly lower in the frail group.

CONCLUSION

We found 5 biomarkers that were associated with frailty (CRP, hemoglobin, albumin, 25OHD and free testosterone in men) belonging to multiple physiological systems. Further cohort studies are needed to verify their ability to screen for frailty.

The Effect of Lactobacillus fermentum ME-3 Treatment on Glycation and Diabetes Complications

SCOPE

Type 2 diabetes (T2D) induces organ damage associated with glycation, among other metabolic pathways. While therapeutic strategies have been tested to reduce the formation and impact of glycation products, results remain equivocal. Anti-diabetic therapies using probiotics have been proposed, but their effect upon glycation has not been reported. Here, the effects of the bacterial strain Lactobacillus fermentum ME-3 on glycation and T2D-related complications in a mouse model of T2D are investigated.

METHODS & RESULTS

Wild-type LepR^db/+ and diabetic LepR^db/db littermates receive a daily gavage of either water or the probiotic ME-3 strain (10¹⁰ CFU). Glycation markers, fructoselysine-derived furosine (FL-furosine) and carboxymethyllysine (CML), are quantified in four major organs and plasma using stable-isotope dilution LC-MS/MS. After 12 weeks of ME-3 treatment, diabetic mice gain less weight and exhibit an apparently improved glucose tolerance. The ME-3 treatment reduces median renal levels of FL-furosine in both genotypes by 12-15%, and renal and pulmonary free-CML in diabetic mice by 30% and 18%, respectively. Attenuated hepatic steatosis and an improved plasma lipid profile are also observed with treatment in both genotypes, while the gut microbiota profile is unchanged.

CONCLUSION

L. fermentum ME-3 has therapeutic potential for reducing the formation/accumulation of some glycation products in kidneys and attenuating some common diabetes-related complications.

The LepRdb/db mice model for studying glycation in the context of diabetes

BACKGROUND

Early (furosine) and advanced (carboxymethyllysine, CML) products of glycation (AGEs) have been reported as increased in plasma, tissues, and organs of diabetic people, indicating a direct link between glycation and type 2 diabetes (T2D). While murine models present some of the characteristics observed in diabetic humans, their pertinence as models of glycation, particularly for T2D, remains poorly described. The aim of this study was to characterize and compare glycation in several organs of two commonly studied murine models of T2D using stable isotope dilution liquid chromatography tandem mass spectrometry (LC-MS/MS).

METHODS

Defining parameters of type 2 diabetes including body weight, fasting glycaemia, and glucose intolerance were measured in three different C57BL6 mouse models of T2D-the genetic LepR^db/db (db/db) model and two diet-induced obesity (DIO) models-and their respective controls. Furosine, free, and protein-bound CML were quantified in kidneys, lungs, heart, and liver by LC-MS/MS.

RESULTS

The obesity, hyperglycaemia, and glucose intolerance in db/db mice was accompanied by an increase of furosine and protein-bound CML levels in all organs relative to controls. The DIO models took several months to become obese, exhibited less severe hyperglycaemia and glucose intolerance, while glycation products were not significantly different between these groups (with the exception of furosine in liver and CML in lungs).

CONCLUSIONS

The db/db model better reflected the characteristics of human T2D compared with the DIO models and exhibited greater formation and accumulation of both furosine and protein-bound CML in all of the organs tested here.

Occurrence and Dynamism of Lactic Acid Bacteria in Distinct Ecological Niches: A Multifaceted Functional Health Perspective

Lactic acid bacteria (LAB) are representative members of multiple ecosystems on earth, displaying dynamic interactions within animal and plant kingdoms in respect with other microbes. This highly heterogeneous phylogenetic group has coevolved with plants, invertebrates, and vertebrates, establishing either mutualism, symbiosis, commensalism, or even parasitism-like behavior with their hosts. Depending on their location and environment conditions, LAB can be dominant or sometimes in minority within ecosystems. Whatever their origins and relative abundance in specific anatomic sites, LAB exhibit multifaceted ecological and functional properties. While some resident LAB permanently inhabit distinct animal mucosal cavities, others are provided by food and may transiently occupy the gastrointestinal tract. It is admitted that the overall gut microbiome has a deep impact on health and diseases. Here, we examined the presence and the physiological role of LAB in the healthy human and several animal microbiome. Moreover, we also highlighted some dysbiotic states and related consequences for health, considering both the resident and the so-called "transionts" microorganisms. Whether LAB-related health effects act collectively or follow a strain-specificity dogma is also addressed. Besides the highly suggested contribution of LAB to interplay with immune, metabolic, and even brain-axis regulation, the possible involvement of LAB in xenobiotic detoxification processes and metal equilibrium is also tackled. Recent technological developments such as functional metagenomics, metabolomics, high-content screening and design in vitro and in vivo experimental models now open new horizons for LAB as markers applied for disease diagnosis, susceptibility, and follow-up. Moreover, identification of general and more specific molecular mechanisms based on antioxidant, antimicrobial, anti-inflammatory, and detoxifying properties of LAB currently extends their selection and promising use, either as probiotics, in traditional and functional foods, for dedicated treatments and mostly for maintenance of normobiosis and homeostasis.

Advanced glycation end products receptor RAGE controls myocardial dysfunction and oxidative stress in high-fat fed mice by sustaining mitochondrial dynamics and autophagy-lysosome pathway

Oxidative stress and mitochondrial dysfunction are recognized as major contributors of cardiovascular damage in diabetes and high fat diet (HFD) fed mice. Blockade of receptor for advanced glycation end products (RAGE) attenuates vascular oxidative stress and development of atherosclerosis. We tested whether HFD-induced myocardial dysfunction would be reversed in RAGE deficiency mice, in association with changes in oxidative stress damage, mitochondrial respiration, mitochondrial fission and autophagy-lysosomal pathway. Cardiac antioxidant capacity was upregulated in RAGE^-/^- mice under normal diet as evidenced by increased superoxide dismutase and sirtuin mRNA expressions. Mitochondrial fragmentation and mitochondrial fission protein Drp1 and Fis1 expressions were increased in RAGE^-/^- mice. Autophagy-related protein expressions and cathepsin-L activity were increased in RAGE^-/^- mice suggesting sustained autophagy-lysosomal flux. HFD induced mitochondrial respiration defects, cardiac contractile dysfunction, disrupted mitochondrial dynamics and autophagy inhibition, which were partially prevented in RAGE^-/^- mice. Our results suggest that cardioprotection against HFD in RAGE^-/^- mice include reactivation of autophagy, as inhibition of autophagic flux by chloroquine fully abrogated beneficial myocardial effects and its stimulation by rapamycin improved myocardial function in HFD wild type mice. As mitochondrial fission is necessary to mitophagy, increased fragmentation of mitochondrial network in HFD RAGE^-/^- mice may have facilitated removal of damaged mitochondria leading to better mitochondrial quality control. In conclusion, modulation of RAGE pathway may improve mitochondrial damage and myocardial dysfunction in HFD mice. Attenuation of cardiac oxidative stress and maintenance of healthy mitochondria population ensuring adequate energy supply may be involved in myocardial protection against HFD.

How Can Diet Affect the Accumulation of Advanced Glycation End-Products in the Human Body?

The accumulation of advanced glycation end products (AGEs) is associated with the complications of diabetes, kidney disease, metabolic disorders and degenerative diseases. It is recognized that the pool of glycation products found in the human body comes not only from an endogenous formation, but also from a dietary exposure to exogenous AGEs. In recent years, the development of pharmacologically-active ingredients aimed at inhibiting endogenous glycation has not been successful. Since the accumulation of AGEs in the human body appears to be progressive throughout life, an early preventive action against glycation could be effective through dietary adjustments or supplementation with purified micronutrients. The present article provides an overview of current dietary strategies tested either in vitro, in vivo or both to reduce the endogenous formation of AGEs and to limit exposure to food AGEs.