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Chemical warfare nerve agents (CWNA) are neurotoxic chemicals unethically used as agents of mass destruction by terrorist outfits and during war. The available antidote against CWNA-mediated toxicity is not sufficiently effective and possesses several limitations. As a countermeasure, paraoxonase 1 (PON1), a catalytic bioscavenger, is being developed as a prophylactic treatment. However, the catalytic activity and substrate specificity of human PON1 are insufficient to be used as a potential antidote. Several laboratories have made different approaches to enhance the CWNA hydrolytic activity against various nerve agents. This review explores the holistic view of PON1 as a potential prophylactic agent against G-series CWNA poisoning, from its initial development to recent advancements and limitations. Apart from this, the review also provides an overview of all available PON1 variants that could be used as a potential prophylactic agent and discusses several possible ways to counteract immunogenicity.

Background Interferon regulatory factor-1 (IRF1) is a transcription factor that plays a significant role in various biological processes, including inflammatory injury, viral infection, cell death, and immune responses, and it has been extensively studied in the context of different lung diseases. However, the mechanism underlying its involvement in lung fibrosis remains largely unknown. Methods Wild type (WT) mice, IRF1 global-null mice ( Irf1 −/− ) were subjected to a bleomycin-induced lung fibrosis model to enable examination of the role of IRF1 in lung fibrosis. Proteomic analysis of lung tissue from WT and Irf1 −/− mice treated with saline or bleomycin was performed to explore the mechanism of IRF1 in regulating lung fibrosis. Results In the bleomycin-induced fibrosis mouse model, increased expression of IRF1 was observed. Irf1 knockout mice displayed decreased lung fibrosis relative to WT mice following treatment with bleomycin. The protein expression of fibronectin, as assessed by the Western blot analysis of lung tissues, was downregulated in Irf1 −/− mice. We observed a similar reduction in collagen content using hydroxyproline detection. Histologically, there was less collagen deposition in the lungs of Irf1 −/− mice compared with WT mice. Proteomics data revealed that IRF1 may be involved in lung fibrosis via the regulation of ferroptosis. We determined that paraoxonase 1(PON1), a poorly characterized protein in lung fibrosis, was upregulated in Irf1 −/− mice following exposure to bleomycin. In vitro experiments revealed that IRF1 could regulate the level of GSH and MDA through PON1. We also determined that PON1 levels were lower in the plasma of IPF patients compared with healthy controls. Conclusion Our data highlight the importance of IRF1 in the fibrotic process, and PON1 may be a potential mediator of IRF1 in the progression of lung fibrosis.

Objectives The interleukin-6 receptor (IL-6R) blocker tocilizumab (TCZ) reduces inflammatory disease activity in rheumatoid arthritis (RA) but elevates lipid concentrations in some patients. We aimed to characterise the impact of IL-6R inhibition on established and novel risk factors in active RA. Methods Randomised, multicentre, two-part, phase III trial (24-week double-blind, 80-week open-label), MEASURE, evaluated lipid and lipoprotein levels, high-density lipoprotein (HDL) particle composition, markers of coagulation, thrombosis and vascular function by pulse wave velocity (PWV) in 132 patients with RA who received TCZ or placebo. Results Median total-cholesterol, low-density lipoprotein-cholesterol (LDL-C) and triglyceride levels increased in TCZ versus placebo recipients by week 12 (12.6% vs 1.7%, 28.1% vs 2.2%, 10.6% vs −1.9%, respectively; all p<0.01). There were no significant differences in mean small LDL, mean oxidised LDL or total HDL-C concentrations. However, HDL-associated serum amyloid A content decreased in TCZ recipients. TCZ also induced reductions (>30%) in secretory phospholipase A2-IIA, lipoprotein(a), fibrinogen and D-dimers and elevation of paraoxonase (all p<0.0001 vs placebo). The ApoB/ApoA1 ratio remained stable over time in both groups. PWV decreases were greater with placebo than TCZ at 12 weeks (adjusted mean difference 0.79 m/s (95% CI 0.22 to 1.35; p=0.0067)). Conclusions These data provide the first detailed evidence for the modulation of lipoprotein particles and other surrogates of vascular risk with IL-6R inhibition. When compared with placebo, TCZ induced elevations in LDL-C but altered HDL particles towards an anti-inflammatory composition and favourably modified most, but not all, measured vascular risk surrogates. The net effect of such changes for cardiovascular risk requires determination.

Ancestral reconstruction provides instrumental insights regarding the biochemical and biophysical characteristics of past proteins. A striking observation relates to the remarkably high thermostability of reconstructed ancestors. The latter has been linked to high environmental temperatures in the Precambrian era, the era relating to most reconstructed proteins. We found that inferred ancestors of the serum paraoxonase (PON) enzyme family, including the mammalian ancestor, exhibit dramatically increased thermostabilities compared with the extant, human enzyme (up to 30 °C higher melting temperature). However, the environmental temperature at the time of emergence of mammals is presumed to be similar to the present one. Additionally, the mammalian PON ancestor has superior folding properties (kinetic stability)—unlike the extant mammalian PONs, it expresses in E. coli in a soluble and functional form, and at a high yield. We discuss two potential origins of this unexpectedly high stability. First, ancestral stability may be overestimated by a “consensus effect,” whereby replacing amino acids that are rare in contemporary sequences with the amino acid most common in the family increases protein stability. Comparison to other reconstructed ancestors indicates that the consensus effect may bias some but not all reconstructions. Second, we note that high stability may relate to factors other than high environmental temperature such as oxidative stress or high radiation levels. Foremost, intrinsic factors such as high rates of genetic mutations and/or of transcriptional and translational errors, and less efficient protein quality control systems, may underlie the high kinetic and thermodynamic stability of past proteins.

Hyperhomocysteinemia is a risk factor of cardiovascular disease (CVD). High-density lipoprotein (HDL) plays an important role in anti-atherosclerosis, with its anti-atherogenic function attributed to HDL-associated proteins such as apolipoprotein A-I (apoA-I) and paraoxonase 1 (PON1). Homocysteine (Hcy) thiolactone modifies lysine residues in proteins, thereby altering their function. Although dysfunction of apoA-I and PON1 has been reported, the precise modification sites and underlying mechanisms have remained unclear. In this study, we aimed to identify Hcy-thiolactone modification sites on apoA-I and PON1. In addition, we sought to clarify the effects of Hcy-thiolactone on PON1 activity and its distribution. Modification sites were analyzed using MALDI-TOF MS. The effects of Hcy-thiolactone on various specimens, including purified proteins, reconstituted HDL (rHDL), HDL collected by ultracentrifugation, and serum samples, were characterized using enzymatic assays measuring three major PON1 activities (arylesterase, paraoxonase, and lactonase) and Western blotting. Our results demonstrated that while some Hcy-thiolactone modification sites were detected on apoA-I, PON1 itself was not directly modified by Hcy-thiolactone. Thiolactonase activity was reduced by Hcy-thiolactone in large HDL particles. Furthermore, a general reduction of PON1 activity and changes in HDL remodeling and distribution were observed in serum samples treated with Hcy-thiolactone. These findings suggest that PON1 dysfunction induced by Hcy-thiolactone is influenced by alterations in HDL remodeling and the enzyme’s distribution on HDL particles. Analysis of PON1’s distribution dynamics under pathological conditions may provide crucial insights into the mechanism of HDL function decline in CVD.

Background and Objectives: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a clinical pathological syndrome characterized by steatosis and fat accumulation in liver parenchymal cells in patients without a history of excessive alcohol drinking. Currently, there is no definitive treatment for MASLD, and its prevalence increases with age and obesity, and after menopause. Among the ways to treat it, we can mention regular sports exercises and the use of natural supplements. Therefore, the aim of this research is to investigate and compare the effects of aerobic-resistance training with royal jelly supplementation on changes in paraoxonase 1, oxidized LDL, liver function, and lipid profile in postmenopausal women with Dysfunction-Associated Steatotic Liver Disease. Materials and Methods: This semi-experimental study involved 23 women with Dysfunction-Associated Steatotic Liver Disease with an average weight (71.34 ± 11.63 kg), age (48.54 ± 3.88 years), and body mass index (27.63 ± 4.20 kg/m2). They were randomly divided into two groups: exercise + supplement (n = 12) and exercise + placebo (n = 11). Both groups performed eight-station resistance exercises (8–12 repetitions in 2–4 sets) for 8 weeks, with three sessions per week (for 35–40 min, from 10-15 RPE), and then, for 10–15 min of active rest, they performed aerobic exercises with an intensity of 40–85% of the target heart rate, in two-minute intervals with 45 s of active rest. Royal jelly supplement (500 mg on training days, before each training session) was consumed. Blood sampling was done before and 48 h after the last training session. Statistical analysis was performed using a variance test with repeated measures (two groups × two stages of pre-test-post-test) in SPSS software (Version 26) with a significance level of p < 0.05. Results: The results of the statistical analysis show that the effects of eight weeks of exercise + supplement and exercise + placebo on PON1, oxLDL, lipid profiles (HDL, LDL, TC, and TG), and liver enzymes (ALT, AST) in women with non-alcoholic fatty liver showed a significant difference (p < 0.05). The results show a significant increase in PON1 (p = 0.008) and HDL (p = 0.005) in the exercise + supplement group compared to the exercise + placebo group. But significant decreases in oxLDL (p = 0.031), TC (p = 0.045), TG (p = 0.013), LDL (p = 0.027), ALT (p = 0.015) and AST (p = 0.009) were observed in the exercise + supplement group compared to the exercise + placebo group (<0.05). The results show a significant increase in PON1 (p = 0.008) and HDL (p = 0.005) in the exercise + supplement group compared to the exercise + placebo group. However, significant decreases in oxLDL (p = 0.031), TC (p = 0.045), TG (p = 0.013), LDL (p = 0.027), ALT (p = 0.015), and AST (p = 0.009) was observed in the exercise + supplement group compared to the exercise + placebo group. Conclusions: Based on the results, it can be concluded that aerobic-resistance exercises with the addition of royal jelly can probably be an efficient and recommended strategy to minimize the harmful effects of Dysfunction-Associated Steatotic Liver Disease by affecting the activity of liver enzymes, paraoxonase 1, LDL oxidation, and lipid profile. Although exercise alone also yielded favorable results, according to the findings of this research, it can be said that exercise, combined with the use of royal jelly supplements, may have more positive effects on reducing liver complications and improving body function. However, in order to obtain more accurate scientific evidence, it is necessary to investigate more doses and timing of royal jelly in future studies.

There are classes of microbial enzymes that have the ability to degrade harmful organophosphorus (OP) compounds that are present in some pesticides and nerve agents. To date, the most studied and potentially important OP-degrading enzymes are organophosphorus hydrolase (OPH) and organophosphorus acid anhydrolase (OPAA), which have both been characterized from a number of organisms. Here we provide an update of what is experimentally known about OPH and OPAA to include their structures, substrate specificity, and catalytic properties. Current and future potential applications of these enzymes in the hydrolysis of OP compounds are also addressed. [PUBLICATION ABSTRACT]

PON1 is a Ca2+-dependent enzyme that indicates a hydrolytic activity towards a broad spectrum of substrates. The mechanism of hydrolysis catalyzed by this enzyme is poorly understood. It was shown that the active site of PON1 is highly dynamic. The catalytic center of this enzyme consists of side chains of amino acids binding two calcium ions, from which the first one performs a structural function and the other one is responsible for the catalytic properties of PON1. This review summarizes available information on the structure of PONs, the role of amino acids located in the active site in specificity, and multiple substrate affinity of enzymes for understanding and explaining the basis of the physiological function of PONs. Moreover, in this paper, we described the changes in the structure of PONs induced by environmental and genetic factors and their association with diseases. The detoxification efficiency depends on the polymorphism of the PON1 gene, especially Q192R. However, data on the association between single-nucleotide polymorphisms (SNPs) in the PON1 gene and cardiovascular or neurodegenerative diseases are insufficient. The reviewed papers may confirm that PON1 is a very promising tool for diagnostics, but further studies are required.

Thermostability improvement of enzymes used industrially or commercially would develop their capacity and commercial potential due to increased enzymatic competence and cost-effectiveness. Several stabilizing factors have been suggested to be the base of thermal stability, like proline replacements, disulfide bonds, surface loop truncation and ionic pair networks creation. This research evaluated the mechanism of increasing the rigidity of organophosphorus hydrolase enzyme by flexible loop truncation. Bioinformatics analysis revealed that the mutated protein retains its stability after loop truncation (five amino acids deleted). The thermostability of the wild-type (OPH-wt) and mutated (OPH-D5) enzymes were investigated by half-life, ΔGi, and fluorescence and far-UV CD analysis. Results demonstrated an increase half-life and ΔGi in OPH-D5 compared to OPH-wt. These results were confirmed by extrinsic fluorescence and circular dichroism (CD) spectrometry experiments, therefore, as rigidity increased in OPHD5 after loop truncation, half-life and ΔGi also increased. Based on these findings, a strong case is presented for thermostability improvement of OPH enzyme by flexible loop truncation after bioinformatics analysis.

Members of the serum paraoxonase (PON) family have been identified in mammals and other vertebrates, and in invertebrates. PONs exhibit a wide range of physiologically important hydrolytic activities, including drug metabolism and detoxification of nerve agents. PON1 and PON3 reside on high-density lipoprotein (HDL, 'good cholesterol') and are involved in the prevention of atherosclerosis. We describe the first crystal structure of a PON family member, a variant of PON1 obtained by directed evolution, at a resolution of 2.2 Å. PON1 is a six-bladed β-propeller with a unique active site lid that is also involved in HDL binding. The three-dimensional structure and directed evolution studies permit a detailed description of PON1's active site and catalytic mechanism, which are reminiscent of secreted phospholipase A2, and of the routes by which PON family members diverged toward different substrate and reaction selectivities.