Recent Developments in Immune Activation by Uric Acid Crystals

A risk model for the early diagnosis of acute myocardial infarction in patients with chronic kidney disease

Introduction

Acute myocardial infarction (AMI) remains a critical disease, characterized by a high fatality rate in several countries. In clinical practice, the incidence of AMI is increased in patients with chronic kidney disease (CKD). However, the early diagnosis of AMI in the above group of patients is still poor.

Methods

In the present study, a total of 829 patients with CKD, defined by an estimated glomerular filtration rate (eGFR) of <60 ml/min/1.73 m2 or 60-90 ml/min/1.73 m2 for patients with mildly reduced kidney function, who attended the Sichuan Provincial People's Hospital (SPPH) between January 2018 and November 2022 were enrolled. All patients underwent coronary angiography due to the presence of typical or atypical symptoms of AMI. Patients were divided into the following two groups: The training cohort, including 255 participants with AMI and 242 without AMI; and the testing cohort, including 165 and 167 subjects with and without AMI, respectively. Furthermore, a forward stepwise regression model and a multivariable logistic regression model, named SPPH-AMI-model, were constructed to select significant predictors and assist the diagnosis of AMI in patients with CKD, respectively.

Results

The following factors were evaluated in the model: Smoking status, high sensitivity cardiac troponin I, serum creatinine and uric acid levels, history of percutaneous coronary intervention and electrocardiogram. Additionally, the area under the curve (AUC) of the receiver operating characteristic curve were determined in the risk model in the training set [AUC, 0.78; 95% confidence interval (CI), 0.74-0.82] vs. the testing set (AUC, 0.74; 95% CI, 0.69-0.79) vs. the combined set (AUC, 0.76; 95% CI, 0.73-0.80). Finally, the sensitivity and specificity rates were 71.12 and 71.21%, respectively, the percentage of cases correctly classified was 71.14%, while positive and negative predictive values of 71.63 and 70.70%, respectively, were also recorded.

Discussion

The results of the current study suggested that the SPPH-AMI-model could be currently considered as the only risk scoring system for the early diagnosis of AMI in patients with CKD. This method could help clinicians and emergency physicians to quickly and accurately diagnose AMI in patients with CKD to promote the immediate and effective treatment of these patients.

Enhanced mucosal immune responses and reduced viral load in the respiratory tract of ferrets to intranasal lipid nanoparticle-based SARS-CoV-2 proteins and mRNA vaccines

BACKGROUND

Unlike the injectable vaccines, intranasal lipid nanoparticle (NP)-based adjuvanted vaccine is promising to protect against local infection and viral transmission. Infection of ferrets with SARS-CoV-2 results in typical respiratory disease and pathology akin to in humans, suggesting that the ferret model may be ideal for intranasal vaccine studies.

RESULTS

We developed SARS-CoV-2 subunit vaccine containing both Spike receptor binding domain (S-RBD) and Nucleocapsid (N) proteins (NP-COVID-Proteins) or their mRNA (NP-COVID-mRNA) and NP-monosodium urate adjuvant. Both the candidate vaccines in intranasal vaccinated aged ferrets substantially reduced the replicating virus in the entire respiratory tract. Specifically, the NP-COVID-Proteins vaccine did relatively better in clearing the virus from the nasal passage early post challenge infection. The immune gene expression in NP-COVID-Proteins vaccinates indicated increased levels of mRNA of IFNα, MCP1 and IL-4 in lungs and nasal turbinates, and IFNγ and IL-2 in lungs; while proinflammatory mediators IL-1β and IL-8 mRNA levels in lungs were downregulated. In NP-COVID-Proteins vaccinated ferrets S-RBD and N protein specific IgG antibodies in the serum were substantially increased at both day post challenge (DPC) 7 and DPC 14, while the virus neutralizing antibody titers were relatively better induced by mRNA versus the proteins-based vaccine. In conclusion, intranasal NP-COVID-Proteins vaccine induced balanced Th1 and Th2 immune responses in the respiratory tract, while NP-COVID-mRNA vaccine primarily elicited antibody responses.

CONCLUSIONS

Intranasal NP-COVID-Proteins vaccine may be an ideal candidate to elicit increased breadth of immunity against SARS-CoV-2 variants.

FGF21 attenuates high uric acid‑induced endoplasmic reticulum stress, inflammation and vascular endothelial cell dysfunction by activating Sirt1

Uric acid (UA) is the final oxidation product of purine metabolism. Hyperuricemia has been previously reported to contribute to vascular endothelial dysfunction and the development of cardiovascular diseases, metabolic syndrome and chronic kidney diseases. In addition, it has been reported that fibroblast growth factor 21 (FGF21) can exert regulatory effects on UA‑induced lipid accumulation. Therefore, the present study aimed to investigate the possible role of FGF21 in HUVEC cell injury induced by UA. The study used UA to induce HUVEC cell injury, inhibited sirtuin 1 (Sirt1) expression using EX527 and overexpressed FGF21 by transfection. Subsequently, reverse transcription‑quantitative PCR was performed to measure the mRNA expression levels of FGF21, Sirt1 and inflammatory cytokines TNF‑α, IL‑1β and IL‑6, whereas western blotting was performed to measure their corresponding protein expression levels including FGF21, Sirt1, NLR family pyrin domain containing 3, pro‑caspase1, apoptosis‑associated speck‑like protein containing a CARD, activating transcription factor 4, C/EBP homologous protein and eukaryotic initiation factor 2. Furthermore, dichloro‑dihydro‑fluorescein diacetate staining was performed to measure intracellular reactive oxygen species (ROS) generation in HUVECs. The levels of ROS and nitric oxide were also quantified using commercial assay kits. The results demonstrated that overexpression of FGF21 significantly inhibited UA treatment‑induced endoplasmic reticulum (ER) stress, inflammation and oxidative stress in HUVECs. Furthermore, overexpression of FGF21 significantly activated Sirt1. The sirt1 inhibitor, EX527, significantly abrogated the suppressive effects of FGF21 overexpression on ER stress, inflammation and oxidative stress in UA‑stimulated HUVECs. To conclude, results of the present study suggested that FGF21 may attenuate UA‑induced ER stress, inflammation and vascular endothelial cell dysfunction by activating Sirt1. Therefore, FGF21 may be a potential effective target for the future treatment of vascular endothelial cell dysfunction.

DAMPs in Unilateral Ureteral Obstruction

Damage-associated molecular patterns (DAMPs) are released from tubular and interstitial cells in the kidney after unilateral ureteral obstruction (UUO). DAMPs are recognized by pattern recognition receptors (PRRs), which mediate the initiation of an immune response and the release of inflammatory cytokines. The animal model of UUO is used for various purposes. UUO in adult mice serves as a model for accelerated renal fibrosis, which is a hallmark of progressive renal disease. UUO in adult mice enables to study cell death, inflammation, and extracellular matrix deposition in the kidney. Neonatal UUO is a model for congenital obstructive nephropathies. It studies inflammation, apoptosis, and interstitial fibrosis in the neonatal kidney, when nephrogenesis is still ongoing. Following UUO, several DAMPs as well as DAMP receptors are upregulated. In adult UUO, soluble uric acid is upregulated and activates the NOD-like receptor family, pyrin domain containing-3 (NLRP3) inflammasome, which promotes fibrosis, apoptosis, and reactive oxygen species (ROS) injury. Further DAMPs associated with UUO are uromodulin, members of the IL-1 family, and necrotic cell DNA, all of which promote sterile inflammation. In neonatal UUO, the receptor for advanced glycation endproducts (RAGE) is highly upregulated. RAGE is a ligand for several DAMPs, including high mobility group box 1 (HMGB1) and S100 proteins, which play an important role in renal fibrosis. Additionally, necroptosis is an important mechanism of cell death, besides apoptosis, in neonatal UUO. It is highly inflammatory due to release of cytokines and specific DAMPs. The release and recognition of DAMPs initiate sterile inflammation, which makes them good candidates to develop and improve diagnostic and therapeutic strategies in renal fibrosis and congenital obstructive nephropathies.

Liposomal nanoparticle-based conserved peptide influenza vaccine and monosodium urate crystal adjuvant elicit protective immune response in pigs

Background

Influenza (flu) is a constant threat to humans and animals, and vaccination is one of the most effective ways to mitigate the disease. Due to incomplete protection induced by current flu vaccines, development of novel flu vaccine candidates is warranted to achieve greater efficacy against constantly evolving flu viruses.

Methods

In the present study, we used liposome nanoparticle (<200 nm diameter)-based subunit flu vaccine containing ten encapsulated highly conserved B and T cell epitope peptides to induce protective immune response against a zoonotic swine influenza A virus (SwIAV) H1N1 challenge infection in a pig model. Furthermore, we used monosodium urate (MSU) crystals as an adjuvant and co-administered the vaccine formulation as an intranasal mist to flu-free nursery pigs, twice at 3-week intervals.

Results

Liposome peptides flu vaccine delivered with MSU adjuvant improved the hemagglutination inhibition antibody titer and mucosal IgA response against the SwIAV challenge and also against two other highly genetically variant IAVs. Liposomal vaccines also enhanced the frequency of peptides and virus-specific T-helper/memory cells and IFN-γ response. The improved specific cellular and mucosal humoral immune responses in adjuvanted liposomal peptides flu vaccine partially protected pigs from flu-induced fever and pneumonic lesions, and reduced the nasal virus shedding and viral load in the lungs.

Conclusion

Overall, our study shows great promise for using liposome and MSU adjuvant- based subunit flu vaccine through the intranasal route, and provides scope for future, pre-clinical investigations in a pig model for developing potent human intranasal subunit flu vaccines.

Serum Uric Acid as an Independent Risk Factor for the Presence and Severity of Early-Onset Coronary Artery Disease: A Case-Control Study

Serum uric acid (UA) is the final product of purine metabolism in humans. The present study is aimed at identifying the potential association between serum UA and early-onset coronary artery disease (EOCAD). The study population consisted of 1093 EOCAD patients aged ≤50 years, and 1117 age- and sex-matched apparently healthy people served as controls. The concentrations of UA were measured by uricase method. The severity of CAD was evaluated by Gensini score. The mean serum level of UA was 5.843 ± 1.479 mg/dl in EOCAD patients and 5.433 ± 1.529 mg/dl in controls. Serum UA levels were significantly higher in the EOCAD group than those in the control group (P < 0.001) and was an independent risk factor for EOCAD (OR = 1.100, 95% CI: 1.022–1.185). The early-onset myocardial infarction patients with 3-vessel disease had higher serum UA levels than those with 1- or 2-vessel disease. The serum UA levels of EOCAD patients with acute coronary syndrome were significantly higher than those with chronic coronary artery disease. EOCAD patients with hyperuricemia had higher Gensini scores than those without hyperuricemia. In addition, the serum UA levels were affected by drinking (P < 0.01) and were positively correlated with serum creatinine (r = 0.323) and weight (r = 0.327). Our results show that serum UA was an independent risk factor for EOCAD. The serum UA levels were associated with the presence and severity of EOCAD and suggested that UA may be involved in the progression of EOCAD.

Inflammatory Alteration of Human T Cells Exposed Continuously to Asbestos

Asbestos is a known carcinogen and exposure can lead to lung cancer and malignant mesothelioma. To examine the effects of asbestos fibers on human immune cells, the human T cell leukemia/lymphoma virus (HTLV)-1 immortalized human T cell line MT-2 was employed. Following continuous exposure to asbestos fibers for more than eight months, MT-2 sublines showed acquisition of resistance to asbestos-induced apoptosis with decreased death signals and increased surviving signals. These sublines showed various characteristics that suggested a reduction in anti-tumor immunity. On the other hand, inflammatory changes such as expression of MMP7, CXCR5, CXCL13 and CD44 was found to be markedly higher in sublines continuously exposed to asbestos compared with original MT-2 cells. All of these molecules contribute to lung inflammation, T and B cell interactions and connections between mesothelial cells and T cells. Thus, further investigation focusing on these molecules may shed light on the role of chronic inflammation caused by asbestos exposure and the occurrence of malignant mesothelioma. Finally, regarding peripheral T cells from healthy donors (HD) and asbestos-exposed patients with pleural plaque (PP) or malignant pleural mesothelioma (MPM), following stimulation of CD4+ T cells, T cells from MPM patients showed reduced potential of interferon (IFN)-γ expression. Moreover, levels of interleukin (IL)-6, one of the most important cytokines in chronic inflammation, in cultured supernatants were higher in PP and MPM patients compared with HD. Overall, asbestos-induced chronic inflammation in the lung as well as the pleural cavity may facilitate the onset of asbestos-induced cancers due to alterations in the interactions among fibers, immune cells such as T and B cells and macrophages, and mesothelial and lung epithelial cells. Further investigations regarding chronic inflammation caused by asbestos fibers may assist in identifying molecular targets for preventive and therapeutic strategies related to the effects of asbestos exposure.

Validation of a multi-analyte HPLC-DAD method for determination of uric acid, creatinine, homovanillic acid, niacinamide, hippuric acid, indole-3-acetic acid and 2-methylhippuric acid in human urine

During the last decades exposure sciences and epidemiological studies attracts more attention to unravel the mechanisms for the development of chronic diseases. According to this an existing HPLC-DAD method for determination of creatinine in urine samples was expended for seven analytes and validated. Creatinine, uric acid, homovanillic acid, niacinamide, hippuric acid, indole-3-acetic acid, and 2-methylhippuric acid were separated by gradient elution (formate buffer/methanol) using an Eclipse Plus C18 Rapid Resolution column (4.6mm×100mm). No interfering signals were detected in mobile phase. After injection of blank urine samples signals for the endogenous compounds but no interferences were detected. All analytes were linear in the selected calibration range and a non weighted calibration model was chosen. Bias, intra-day and inter-day precision for all analytes were below 20% for quality control (QC) low and below 10% for QC medium and high. The limits of quantification in mobile phase were in line with reported reference values but had to be adjusted in urine for homovanillic acid (45mg/L), niacinamide 58.5(mg/L), and indole-3-acetic acid (63mg/L). Comparison of creatinine data obtained by the existing method with those of the developed method showing differences from -120mg/L to +110mg/L with a mean of differences of 29.0mg/L for 50 authentic urine samples. Analyzing 50 authentic urine samples, uric acid, creatinine, hippuric acid, and 2-methylhippuric acid were detected in (nearly) all samples. However, homovanillic acid was detected in 40%, niacinamide in 4% and indole-3-acetic acid was never detected within the selected samples.

An approach to local immunotoxicity induced by adjuvanted vaccines

The occurrence of injection site reactions following immunization is the most frequently reported toxicity manifestation of vaccines; however, the different types of local reactions and the different mechanisms involved are still unclear. Here, the current advances in adjuvants and the role that adjuvants play in local reactions are reviewed. The role of adjuvants in the formation of the loco-regional complex (LRC), which consists of the injection site, draining lymphatic vessels and regional lymph nodes, is also discussed. Finally, strategies and recommendations for the rational design of adjuvanted vaccines are discussed, with a particular interest in the reduction of local inflammation.

Lipid raft redox signaling: molecular mechanisms in health and disease

Lipid rafts, the sphingolipid and cholesterol-enriched membrane microdomains, are able to form different membrane macrodomains or platforms upon stimulations, including redox signaling platforms, which serve as a critical signaling mechanism to mediate or regulate cellular activities or functions. In particular, this raft platform formation provides an important driving force for the assembling of NADPH oxidase subunits and the recruitment of other related receptors, effectors, and regulatory components, resulting, in turn, in the activation of NADPH oxidase and downstream redox regulation of cell functions. This comprehensive review attempts to summarize all basic and advanced information about the formation, regulation, and functions of lipid raft redox signaling platforms as well as their physiological and pathophysiological relevance. Several molecular mechanisms involving the formation of lipid raft redox signaling platforms and the related therapeutic strategies targeting them are discussed. It is hoped that all information and thoughts included in this review could provide more comprehensive insights into the understanding of lipid raft redox signaling, in particular, of their molecular mechanisms, spatial-temporal regulations, and physiological, pathophysiological relevances to human health and diseases.