The roles of adenosine deaminase in autoimmune diseases

Adenosine A2B receptor activation regulates the balance between T helper 17 cells and regulatory T cells, and inhibits regulatory T cells exhaustion in experimental autoimmune myositis

BACKGROUND

Idiopathic inflammatory myopathy (IIM) is a systemic autoimmune disease characterized by skeletal muscle involvement. This study aimed to investigate the role of adenosine receptor signalling pathways in the development of experimental autoimmune myositis (EAM).

METHODS

An ecto-5'-nucleotidase (CD73) inhibitor, adenosine receptor agonists, a hypoxia-inducible factor-1α (HIF-1α) inhibitor or a vehicle were administered to control and EAM mice. Murine splenic CD4+ or regulatory T cells (Tregs) were isolated using magnetic beads and subsequently stimulated with an adenosine A2B receptor agonist, a HIF-1α inhibitor, or vehicle in vitro. In cross-sectional studies, we collected 64 serum samples (69% female, 49 ± 9 years), 63 peripheral blood samples (70% female, 50 ± 11 years), and 34 skeletal muscle samples (71% female, 63 ± 6 years) from patients with IIM. Additionally, 35 serum samples and 30 peripheral blood samples were obtained from age- and sex-matched healthy controls, and six quadriceps muscle samples were collected from patients with osteoarthritis to serve as the normal group.

RESULTS

Patients with IIM exhibited increased CD73 [dermatomyositis (DM), polymyositis (PM): P < 0.01; immune-mediated necrotizing myopathy (IMNM): P < 0.0001] and adenosine deaminase (ADA) expression (DM: P < 0.001; PM, IMNM: P < 0.0001) in the skeletal muscles, and serum ADA levels [56.7 (95% CI: 53.7, 58.7) vs. 198.8 (95% CI: 186.2, 237.3) ng/μL, P < 0.0001]. Intervention with a CD73 inhibitor exacerbated (P = 0.0461), whereas adenosine receptor agonists (A1: P = 0.0009; A2B: P < 0.0001; A3: P = 0.0001) and the HIF-1α inhibitor (P = 0.0044) alleviated skeletal muscle injury in EAM mice. Elevated expression of programmed cell death protein-1 (PD1: P = 0.0023) and T-cell immunoglobulin and mucin-domain containing-3 (TIM3: P < 0.0001) in skeletal muscles of patients with IIM were correlated with creatine kinase levels (PD1, r = 0.7072, P < 0.0001; TIM3, r = 0.4808, P = 0.0046). PD1+CD4+ (r = 0.3243, P = 0.0115) and PD1+CD8+ (r = 0.3959, P = 0.0017) T cells were correlated with Myositis Disease Activity Assessment Visual Analogue Scale scores (muscle) in IIM. The exhausted Tregs were identified in the skeletal muscles of patients with IIM. Activation of the A2B adenosine receptor downregulated HIF-1α (protein or mRNA level, P < 0.01), resulting in decreased T helper cell 17 (Th17) (13.58% vs. 5.43%, P = 0.0201) and phosphorylated-signal transducer and activator of transcription 3 (p-STAT3)+ Th17 (16.32% vs. 6.73%, P = 0.0029), decreased exhausted Tregs (PD1+ Tregs: 53.55% vs. 40.28%, P = 0.0005; TIM3+ Tregs: 3.93% vs. 3.11%, P = 0.0029), and increased Tregs (0.45% vs. 2.89%, P = 0.0006) in EAM mice.

CONCLUSIONS

The exhausted T cells may be pathogenic in IIM, and the activation of adenosine A2B receptor signalling pathway can regulate Th17/Treg balance and inhibit Tregs exhaustion, thereby slowing EAM disease progression.

The reduced frequency of CD39+CD73+ B cell subsets in SLE patients is correlated with disease activity

BACKGROUND

Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease characterized by immune mechanisms dysregulation, leading to the production of diverse autoantibodies. However, the immune pathways underlying B-cell function and phenotypic abnormalities related to SLE pathogenesis remain incompletely understood.

OBJECTIVE

To explore new markers of SLE activity and potential targets for SLE immunotherapy.

METHODS

Collect peripheral blood mononuclear cells (PBMCs) from SLE patients and healthy controls (HC). Use flow cytometry to detect CD39 and CD73 expression on B cell subsets and enzyme-linked immunosorbent assay (ELISA) to measure adenosine (ADO) concentrations in SLE patients' serum. Compare CD39+CD73+ B cell subsets frequency and ADO concentrations in SLE patients and HC group. Additionally, analyze the correlation between CD39+CD73+ B cell subsets frequency and clinical laboratory parameters.

RESULTS

CD39 and CD73 are simultaneously highly expressed on CD19+ B cell subsets, with significantly lower frequency of CD39+CD73+ B cell subsets in SLE patients compared to HC group. This frequency negatively correlates with Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), C-reactive protein (CRP), and anti-double-stranded DNA (anti-dsDNA) antibodies, while positively correlating with IgM and prothrombin time (PT). Additionally, the frequency of CD39+CD73+ B cell subsets is significantly negatively correlated with IL-6 and IFN-α. In vitro cell experiments demonstrate that adenosine significantly inhibits R848-induced inflammatory cytokine production in a dose-dependent manner.

CONCLUSION

The frequency of CD39+CD73+ B cell subsets of SLE patients is decreased, correlating with clinical laboratory parameters and disease activity. Simultaneously, ADO concentration in the patients' serum is reduced. The CD39+CD73+ B cell/ADO pathway may represent a novel immunotherapy strategy for SLE.

Relationship between type 1 diabetes and autoimmune diseases in european populations: A two-sample Mendelian randomization study

Background

Previous studies have suggested an association between Type 1 diabetes (T1D) and autoimmune diseases (AIDs), but the causal relationship remains unclear. Therefore, this study utilizes publicly available Genome-Wide Association Studies (GWAS) databases and employs a two-sample Mendelian Randomization (MR) approach to explore the causal relationships between T1D and systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and inflammatory bowel disease (IBD).

Methods

Summary GWAS data for T1D, SLE, RA, and IBD were downloaded from open GWAS databases and the International Inflammatory Bowel Disease Genetics Consortium (IIBDGC). We employed a series of methods to select instrumental variables closely related to T1D. To enhance the reliability of our conclusions, we applied multiple robust analytical methods, with the inverse variance weighted (IVW) method as the primary approach. Validation and meta-analysis were conducted using the FinnGen consortium. Additionally, we assessed heterogeneity, pleiotropy, and sensitivity to ensure the robustness of our conclusions.

Results

A potential causal association was found between T1D and SLE (OR = 1.37, 95% CI = 1.26 - 1.49, P < 0.001), which was further confirmed by meta-analysis. Similarly, a potential causal association was found between T1D and RA (OR = 1.32, 95% CI = 1.17 - 1.50, P < 0.001), and this was also confirmed by meta-analysis. Although the association between T1D and IBD showed P < 0.05, the leave-one-out test did not pass, and further meta-analysis indicated no significant statistical association between them.

Conclusion

Our study reveals the relationships between T1D and three clinically common autoimmune diseases (SLE, RA, and IBD). This research supplements previous studies and provides a reference for future clinical work.

Interference of ATP-Adenosine Axis by Engineered Biohybrid for Amplifying Immunogenic Cell Death-Mediated Antitumor Immunotherapy

Immunogenic cell death (ICD) often results in the production and accumulation of adenosine (ADO), a byproduct that negatively impacts the therapeutic effect as well as facilitates tumor development and metastasis. Here, an innovative strategy is elaborately developed to effectively activate ICD while avoiding the generation of immunosuppressive adenosine. Specifically, ZIF-90, an ATP-responsive consumer, is synthesized as the core carrier to encapsulate AB680 (CD73 inhibitor) and then coated with an iron-polyphenol layer to prepare the ICD inducer (AZTF), which is further grafted onto prebiotic bacteria via the esterification reaction to obtain the engineered biohybrid (Bc@AZTF). Particularly, the designed Bc@AZTF can actively enrich in tumor sites and respond to the acidic tumor microenvironment to offload AZTF nanoparticles, which can consume intracellular ATP (iATP) content and simultaneously inhibit the ATP-adenosine axis to reduce the accumulation of adenosine, thereby alleviating adenosine-mediated immunosuppression and strikingly amplifying ICD effect. Importantly, the synergy of anti-PD-1 (αPD-1) with Bc@AZTF not only establishes a collaborative antitumor immune network to potentiate effective tumoricidal immunity but also activates long-lasting immune memory effects to manage tumor recurrence and rechallenge, presenting a new paradigm for ICD treatment combined with adenosine metabolism.

Factors influencing accelerated aging in patients with type 2 diabetes mellitus and coronary heart disease

Objective

To investigate the factors influencing accelerated aging in patients with type 2 diabetes mellitus (T2DM) and coronary heart disease (CHD).

Methods

A total of 216 patients diagnosed with T2DM and CHD between August 2019 and August 2023 at Xuzhou Central Hospital were selected. Patients were divided into an aging group and a non-aging group, based on the positive or negative values of phenotypic age acceleration (PhenoAgeAccel). Logistic regression analysis was conducted. Variables that had a univariate analysis P< 0.05 were included in the multivariate analysis to identify factors influencing aging in patients with T2DM and CHD, and the area under the curve of the model was reported.

Results

This study included 216 patients, with 89 in the accelerated aging group, and 127 in the non-accelerated aging group. The average age of patients was 70.40 (95% CI: 69.10-71.69) years, with 137 males (63.4%). Compared with the non-accelerated aging group, patients in the accelerated aging group were older, with a higher proportion of males, and a higher prevalence of hypertension, stable angina pectoris, and unstable angina pectoris. Multivariate Logistic regression analysis indicated that the absolute value of neutrophils (NEUT#), urea (UREA), adenosine deaminase (ADA), and the triglyceride-glucose index (TyG) were risk factors for accelerated aging, while cholinesterase (CHE) was a protective factor. For each unit increase in NEUT#, UREA, ADA, and TyG, the risk of aging increased by 64%, 48%, 10%, and 789%, respectively. The overall area under the receiver operating characteristic (ROC) curve of the model in the training set was 0.894, with a 95% confidence interval (CI) of 0.851-0.938.

Conclusion

NEUT#, CHE, UREA, ADA, and TyG are predictors of accelerated aging in patients with T2DM and CHD, with the model showing favorable overall predictive performance.

The roles of adenosine signaling in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a complex autoimmune disease with multiple etiological factors. Immune disorder contributes to SLE development and is an important clinical manifestation of SLE patients. Immune dysfunction is characterized by abnormal of B cells, T cells, monocyte-macrophages and dendritic cells (DCs), in both quantity and quality. Adenosine is a critical factor for human immune homeostasis, which acts as an immunosuppressive signal and can prevent the hyperactivity of human immune system. Adenosine levels are significant decreased in serum from SLE patients. Adenosine level is regulated by the CD39, CD73 and adenosine deaminase (ADA). CD39/CD73/ADA catalyzed the cascade enzymatic reaction, which contained the adenosine generation and degradation. Adenosine affects the function of various immune cells via bind to the adenosine receptors, which are expressed on the cell surface. This review aims to export the changes of immune cells and adenosine signal pathway in SLE, as well as the effect of adenosine signal pathway in SLE development.

The Olink proteomics profile in nasal secretion of patients with allergic rhinitis

KEY POINTS

Nasal secretions of allergic rhinitis patients were analyzed by Olink proteomics. Fifteen differentially expressed proteins (DEPs) were identified. The DEPs were significantly correlated with the total nasal symptom scores of patients with allergic rhinitis.

Therapeutic and immunomodulatory potentials of mesenchymal stromal/stem cells and immune checkpoints related molecules

Mesenchymal stromal/stem cells (MSCs) are used in many studies due to their therapeutic potential, including their differentiative ability and immunomodulatory properties. These cells perform their therapeutic functions by using various mechanisms, such as the production of anti-inflammatory cytokines, growth factors, direct cell-to-cell contact, extracellular vesicles (EVs) production, and mitochondrial transfer. However, mechanisms related to immune checkpoints (ICPs) and their effect on the immunomodulatory ability of MSCs are less discussed. The main function of ICPs is to prevent the initiation of unwanted responses and to regulate the immune system responses to maintain the homeostasis of these responses. ICPs are produced by various types of immune system regulatory cells, and defects in their expression and function may be associated with excessive responses that can ultimately lead to autoimmunity. Also, by expressing different types of ICPs and their ligands (ICPLs), tumor cells prevent the formation and durability of immune responses, which leads to tumors' immune escape. ICPs and ICPLs can be produced by MSCs and affect immune cell responses both through their secretion into the microenvironment or direct cell-to-cell interaction. Pre-treatment of MSCs in inflammatory conditions leads to an increase in their therapeutic potential. In addition to the effect that inflammatory environments have on the production of anti-inflammatory cytokines by MSCs, they can increase the expression of various types of ICPLs. In this review, we discuss different types of ICPLs and ICPs expressed by MSCs and their effect on their immunomodulatory and therapeutic potential.

Efficacy and safety of gut microbiota-based therapies in autoimmune and rheumatic diseases: a systematic review and meta-analysis of 80 randomized controlled trials

BACKGROUND

Previous randomized controlled trials (RCTs) suggested that gut microbiota-based therapies may be effective in treating autoimmune diseases, but a systematic summary is lacking.

METHODS

Pubmed, EMbase, Sinomed, and other databases were searched for RCTs related to the treatment of autoimmune diseases with probiotics from inception to June 2022. RevMan 5.4 software was used for meta-analysis after 2 investigators independently screened literature, extracted data, and assessed the risk of bias of included studies.

RESULTS

A total of 80 RCTs and 14 types of autoimmune disease [celiac sprue, SLE, and lupus nephritis (LN), RA, juvenile idiopathic arthritis (JIA), spondyloarthritis, psoriasis, fibromyalgia syndrome, MS, systemic sclerosis, type 1 diabetes mellitus (T1DM), oral lichen planus (OLP), Crohn's disease, ulcerative colitis] were included. The results showed that gut microbiota-based therapies may improve the symptoms and/or inflammatory factor of celiac sprue, SLE and LN, JIA, psoriasis, PSS, MS, systemic sclerosis, Crohn's disease, and ulcerative colitis. However, gut microbiota-based therapies may not improve the symptoms and/or inflammatory factor of spondyloarthritis and RA. Gut microbiota-based therapies may relieve the pain of fibromyalgia syndrome, but the effect on fibromyalgia impact questionnaire score is not significant. Gut microbiota-based therapies may improve HbA1c in T1DM, but its effect on total insulin requirement does not seem to be significant. These RCTs showed that probiotics did not increase the incidence of adverse events.

CONCLUSIONS

Gut microbiota-based therapies may improve several autoimmune diseases (celiac sprue, SLE and LN, JIA, psoriasis, fibromyalgia syndrome, PSS, MS, T1DM, Crohn's disease, and ulcerative colitis).

Circular RNAs: Potential biomarkers and therapeutic targets for autoimmune diseases

The outcomes and prognosis of autoimmune diseases depend on early diagnosis and effective treatments. However, symptoms of early autoimmune diseases are often remarkably similar to many inflammatory diseases, leading to difficulty in precise diagnosis. Circular RNAs (circRNAs) belong to a novel class of endogenous RNAs, functioning as microRNA (miRNA) sponges or participating in protein coding. It has been shown in many studies that patients with autoimmune diseases have aberrant circRNA expression in liquid biopsy samples (such as plasma, saliva, and urine). Thus, circRNAs are potential biomarkers for the diagnosis and prognosis of autoimmune diseases. Moreover, overexpression and depletion of target circRNAs can be utilized as possible therapeutic approaches for treating autoimmune diseases. In this review, we summarized recent progress in the roles of circRNAs in the pathogenesis of autoimmune diseases, including rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, and type 1 diabetes. We also discussed their potential as biomarkers and therapeutic targets.

Prolonged administration of total glucosides of paeony improves intestinal immune imbalance and epithelial barrier damage in collagen-induced arthritis rats based on metabolomics-network pharmacology integrated analysis

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease characterized by synovial inflammation and joint damage with complex pathological mechanisms. In recent years, many studies have shown that the dysregulation of intestinal mucosal immunity and the damage of the epithelial barrier are closely related to the occurrence of RA. Total glucosides of paeony (TGP) have been used clinically for the treatment of RA in China for decades, while the pharmacological mechanism is still uncertain. The purpose of this study was to investigate the regulatory effect and mechanism of TGP on intestinal immunity and epithelial barrier in RA model rats. The results showed that TGP alleviated immune hyperfunction by regulating the ratio of CD3+, CD4+ and CD8+ in different lymphocyte synthesis sites of the small intestine, including Peyer's patches (PPs), intraepithelial lymphocytes (IELs), and lamina propria lymphocytes (LPLs). Specially, TGP first exhibited immunomodulatory effects on sites close to the intestinal lumen (IELs and LPLs), and then on PPs far away from the intestinal lumen as the administration time prolonged. Meanwhile, TGP restores the intestinal epithelial barrier by upregulating the ratio of villi height (V)/crypt depth (C) and expression of tight junction proteins (ZO-1, occludin). Finally, the integrated analysis of metabolomics-network pharmacology was also used to explore the possible regulation mechanism of TGP on the intestinal tract. Metabolomics analysis revealed that TGP reversed the intestinal metabolic profile disturbance in CIA rats, and identified 32 biomarkers and 163 corresponding targets; network pharmacology analysis identified 111 potential targets for TGP to treat RA. By intersecting the results of the two, three key targets such as ADA, PNP and TYR were determined. Pharmacological verification experiments showed that the levels of ADA and PNP in the small intestine of CIA rats were significantly increased, while TGP significantly decreased their ADA and PNP levels. In conclusion, purine metabolism may play an important role in the process of TGP improving RA-induced intestinal immune imbalance and impaired epithelial barrier.

Aedes albopictus salivary adenosine deaminase is an immunomodulatory factor facilitating dengue virus replication

The Asian tiger mosquito, Aedes albopictus, is an important vector for the transmission of arboviruses such as dengue virus (DENV). Adenosine deaminase (ADA) is a well-characterized metabolic enzyme involved in facilitating blood feeding and (or) arbovirus transmission in some hematophagous insect species. We previously reported the immunologic function of ADA by investigating its effect on mast cell activation and the interaction with mast cell tryptase and chymase. The 2-D gel electrophoresis and mass spectrometry analysis in the current study revealed that ADA is present and upregulated following mosquito blood feeding, as confirmed by qRT-PCR and western blot. In addition, the recombinant ADA efficiently converted adenosine to inosine. Challenging the Raw264.7 and THP-1 cells with recombinant ADA resulted in the upregulation of IL-1β, IL-6, TNF-α, CCL2, IFN-β, and ISG15. The current study further identified recombinant ADA as a positive regulator in NF-κB signaling targeting TAK1. It was also found that recombinant Ae. albopictus ADA facilitates the replication of DENV-2. Compared with cells infected by DENV-2 alone, the co-incubation of recombinant ADA with DENV-2 substantially increased IL-1β, IL-6, TNF-α, and CCL2 gene transcripts in Raw264.7 and THP-1 cells. However, the expression of IFN-β and ISG15 were markedly downregulated in Raw264.7 cells but upregulated in THP-1 cells. These findings suggest that the immunomodulatory protein, Ae. albopictus ADA is involved in mosquito blood feeding and may modulate DENV transmission via macrophage or monocyte-driven immune response.

Machine learning encodes urine and serum metabolic patterns for autoimmune disease discrimination, classification and metabolic dysregulation analysis

There is a wide variety of autoimmune diseases (ADs) with complex pathogenesis and their accurate diagnosis is difficult to achieve because of their vague symptoms. Metabolomics has been proven to be an efficient tool in the analysis of metabolic disorders to provide clues about the mechanism and diagnosis of diseases. Previous studies of the metabolomics analysis of ADs were not competent in their discrimination. Herein, a liquid chromatography tandem mass spectrometry (LC-MS) strategy combined with machine learning is proposed for the discrimination and classification of ADs. Urine and serum samples were collected from 267 subjects consisting of 127 healthy controls (HC) and 140 AD patients, including those with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), sicca syndrome (SS), ankylosing spondylitis (AS), systemic scleroderma (SSc) and connective tissue disease (CTD). Machine learning algorithms were encoded for the discrimination and classification of ADs with metabolomic patterns obtained by LC-MS, and satisfactory results were achieved. Notably, urine samples exhibited higher accuracy for disease differentiation and triage than serum samples. Apart from that, differential metabolites were selected and metabolite panels were evaluated to demonstrate their representativeness. Metabolic dysregulations were also investigated to gain more knowledge about the pathogenesis of ADs. This research provides a promising method for the application of metabolomics combined with machine learning in precision medicine.

Fecal microbial biomarkers in older adults with autoimmune diseases

Aim: To analyze the alterations in the fecal microbiota of older adults with autoimmune disease and determine the diagnostic capabilities of microbial biomarkers. Methods: The raw data of fecal samples from 444 older adults from the publicly available American Gut Project database was analyzed. Results: It was found that there were no significant differences in the microbiota richness and evenness between older adults with autoimmune disease and healthy controls. However, significant differences were observed in the microbiota composition and structure. The subject operating characteristic curve of the eight key microbiota was obtained, and the area under curve value was 70.0%. Conclusion: Older adults with autoimmune disease showed changes in intestinal microbiota composition, which can be used as microbial biomarkers.

Urine and serum metabolic profiling combined with machine learning for autoimmune disease discrimination and classification

Precision diagnosis and classification of autoimmune diseases (ADs) is challenging due to the obscure symptoms and pathological causes. Biofluid metabolic analysis has the potential for disease screening, in which high throughput, rapid analysis and minimum sample consumption must be addressed. Herein, we performed metabolomic profiling by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) in urine and serum samples. Combined with machine learning (ML), metabolomic patterns from urine achieved the discrimination and classification of ADs with high accuracy. Furthermore, metabolic disturbances among different ADs were also investigated, and provided information of etiology. These results demonstrated that urine metabolic patterns based on MALDI-MS and ML manifest substantial potential in precision medicine.

Research on the improvement effect of Saposhnikovia divaricata (Trucz.) Schischk on rheumatoid arthritis based on the "component-target-pathway" association

OBJECTIVE

To investigate the therapeutic effect and mechanism of the traditional Chinese medicine Saposhnikovia divaricata (Trucz.) Schischk in rats with complete Freund's adjuvant-induced rheumatoid arthritis (RA).

METHODS

The chemical targets and RA targets of Saposhnikovia divaricata (Trucz.) Schischk were acquired by the network pharmacological method. The complete Freund's adjuvant-induced rat RA model was used to further explore the mechanism of Saposhnikovia divaricata (Trucz.) Schischk in improving RA. Pathological changes in the volume of toes, body weight and synovial tissues of joints as well as serum inflammatory factor levels before and after the intervention of Saposhnikovia divaricata (Trucz.) Schischk were investigated. The key metabolic pathways were screened by correlations between metabolites and key targets. Finally, a quantitative analysis of key targets and metabolites was experimentally validated.

RESULTS

Saposhnikovia divaricata (Trucz.) Schischk administration increased body weight, mitigated foot swelling and downregulated inflammatory cytokine levels in model rats. The histopathology showed that treatment with Saposhnikovia divaricata (Trucz.) Schischk can induce inflammatory cell infiltration and synovial hyperplasia and obviously reduce cartilage injuries, thus improving arthritis symptoms in rats. According to the network pharmacology-metabonomics association analysis results, the purine metabolic signaling pathway might be the key pathway for RA intervention with Saposhnikovia divaricata (Trucz.) Schischk. Targeted metabonomics, Western blotting (WB) and reverse transcription-polymerase chain reaction (RT‒PCR) assays showed that the recombinant adenosine deaminase (ADA) mRNA expression level and metabolic level of inosine in Saposhnikovia divaricata (Trucz.) Schischk administration group were lower than those of the model group. This reflected that Saposhnikovia divaricata (Trucz.) Schischk could improve RA by downregulating ADA mRNA expression levels and the metabolic level of inosine in the purine signaling pathway.

CONCLUSION

Based on the "component-disease-target" association analysis, this study concludes that Saposhnikovia divaricata (Trucz.) Schischk improves complete Freund's adjuvant-induced RA symptoms in rats mainly by downregulating ADA mRNA expression levels in the purine metabolic signaling pathway, mitigating foot swelling, improving the levels of serum inflammatory factors (IL-1β, IL-6 and TNF-α), and decreasing the ADA protein expression level to intervene in purine metabolism.

Correlation of serum adenosine deaminase activity with disease activity in patients with primary Sjögren's syndrome

BACKGROUND

Primary Sjögren's syndrome (pSS) is a chronic inflammatory autoimmune disease primarily affecting the exocrine glands, which has a variety of clinical manifestations and unclear pathogenic mechanisms. Adenosine deaminase (ADA) is an enzyme involved in the breakdown of purines, and changes in its activity have been associated with a number of autoimmune diseases. This study aims to investigate the relationship between serum ADA activity and disease activity in patients with pSS.

METHODS

In this study, 196 patients with pSS and 196 healthy controls were enrolled. Serum ADA activity and clinical laboratory parameters were collected and analyzed in both groups. Pearson correlation analysis was used to examine the correlation between ADA activity and clinical laboratory parameters, as well as the correlation between ADA activity and the disease activity score.

RESULTS

Compared with healthy controls, the activity of ADA in the serum of pSS patients was significantly increased (P < 0.0001), and the ADA activity was significantly decreased after immunosuppressive treatment (P < 0.0001). Correlation analysis revealed that the activity of ADA was significantly positively correlated with erythrocyte sedimentation rate (ESR) (r = 0.3, P < 0.0001) and serum immunoglobulin G (IgG) levels (r = 0.5, P < 0.0001), and significantly negatively correlated with high-density lipoprotein (HDL) (r = -0.4, P < 0.0001). Furthermore, there was a significant positive correlation between ADA activity and the disease activity score as measured by the Sjögren's Syndrome Disease Activity Index (SSDAI) (r = 0.4, P < 0.0001).

CONCLUSION

This study found that patients with pSS have higher activity of ADA in serum, which is associated with disease activity as measured by SSDAI. These results suggest that ADA activity may be a potential biomarker for evaluating disease activity and treatment efficacy in pSS patients.Additionally, ADA may be a potential target for the treatment of pSS patients.

The potential of CD38 protein as a target for autoimmune diseases

Cluster of differentiation 38 (CD38) is a multifunctional cell surface protein involved in nicotinamide adenine dinucleotide (NAD⁺) homeostasis in types of cells and tissues, which can be found in many immune cells and non-immune cells. Previous studies have shown that CD38 plays an important role in regulating innate immunity. Recently, many studies have revealed the importance of CD38 in autoimmune diseases, such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), multiple sclerosis (MS), type 1 diabetes (T1D) and inflammatory bowel disease, among others. In this report, we will briefly discuss the complex immunological functions of CD38 and focus on recent advances in the role of CD38 in the development and pathogenesis of autoimmune diseases, as well as their potential as therapeutic targets for systemic diseases, intending to make a comprehensive understanding of CD38 and its promising therapeutic potential in these systemic diseases.

Non-carcinogenic/non-nephrotoxic aristolochic acid IVa exhibited anti-inflammatory activities in mice

Aristolochic acid (AA)-containing herbs have been prescribed for thousands of years as anti-inflammatory drugs, despite the active pharmaceutical ingredients remaining unclear. However, exposure to AAI and AAII has been proven to be a significant risk factor for severe nephropathy and carcinogenicity. AAIVa, an analogue abundant in AA-containing herbs, showed neither carcinogenicity nor nephrotoxicity in our study and other reports, implying that the pharmacological effects of AAIVa on inflammation are worth studying. Herein, we employed RAW 264.7 cells, the ear edema mouse model, and the lipopolysaccharide (LPS)-induced systematic inflammation model in TNF-IRES-Luc mice (tracking TNFα luciferase activities in real-time) to evaluate the anti-inframammary effect of AAIVa. Our results showed that AAIVa could decrease pro-inflammatory cytokines (TNFα and IL-6) production in LPS-stimulated RAW 264.7 cells, indicating its anti-inflammatory effects in vitro. Furthermore, the application of AAIVa (400 and 600 μg/ear) could significantly inhibit phorbol 12-myristate 13-acetate-induced ear edema, suggesting its topical anti-inflammatory activity in vivo. Moreover, LPS-stimulated TNF-IRES-Luc mice were used to investigate the onset and duration of AAIVa on systematic inflammation. A single dosage of AAIVa (100 mg/kg, i.g.) could suppress LPS-triggered inflammation, by decreasing luciferase activities of TNFα at 3 h in TNF-IRES-Luc mice. In addition, the online pharmacological databases predicted that AAIVa might target the regulation of T cell activation-related protein (ADA, ADORA2A, ERBB2) to exhibit anti-inflammatory effect. In conclusion, we demonstrated that AAIVa had anti-inflammatory effect for the first time; our findings are constructive for further studies on pharmacological mechanism of AAIVa.

Multisite chronic pain and the risk of autoimmune diseases: A Mendelian randomization study

Background

Accumulating evidence has demonstrated that an association between chronic pain and autoimmune diseases (AIDs). Nevertheless, it is unclear whether these associations refer to a causal relationship. We used a two-sample Mendelian randomization (MR) method to determine the causal relationship between chronic pain and AIDs.

Methods

We assessed genome-wide association study (GWAS) summary statistics for chronic pain [multisite chronic pain (MCP) and chronic widespread pain (CWP)], and eight common AIDs, namely, amyotrophic lateral sclerosis (ALS), celiac disease (CeD), inflammatory bowel disease (IBD), multiple sclerosis (MS), rheumatoid arthritis (RA), systemic lupus Erythematosus (SLE), type 1 diabetes (T1D) and psoriasis. Summary statistics data were from publicly available and relatively large-scale GWAS meta-analyses to date. The two-sample MR analyses were first performed to identify the causal effect of chronic pain on AIDs. The two-step MR and multivariable MR were used to determine if mediators (BMI and smoking) causally mediated any connection and to estimate the proportion of the association mediated by these factors combined.

Results

With the utilization of MR analysis, multisite chronic pain was associated with a higher risk of MS [odds ratio (OR) = 1.59, 95% confidence interval (CI) = 1.01-2.49, P = 0.044] and RA (OR = 1.72, 95% CI = 1.06-2.77, P = 0.028). However, multisite chronic pain had no significant effect on ALS (OR = 1.26, 95% CI = 0.92-1.71, P = 0.150), CeD (OR = 0.24, 95% CI = 0.02-3.64, P = 0.303), IBD (OR = 0.46, 95% CI = 0.09-2.27, P = 0.338), SLE (OR = 1.78, 95% CI = 0.82-3.88, P = 0.144), T1D (OR = 1.15, 95% CI = 0.65-2.02, P = 0.627) or Psoriasis (OR = 1.59, 95% CI = 0.22-11.26, P = 0.644). We also found positive causal effects of MCP on BMI and causal effects of BMI on MS and RA. Moreover, there were no causal connections between genetically predicted chronic widespread pain and the risk of most types of AIDs disease.

Conclusion

Our MR analysis implied a causal relationship between MCP and MS/RA, and the effect of MCP on MS and RA may be partially mediated by BMI.

Bio-Inspired Deaminative Hydroxylation of Aminoheterocycles and Electron-Deficient Anilines

Among the tools available to chemists for drug design of bioactive compounds, the bioisosteric replacement of atoms or groups of atoms is the cornerstone of modern strategies. Despite the undeniable interest in amino-to-hydroxyl interchange, enzymatic deaminative hydroxylation remains unmatched. Herein, we report a user friendly and safe procedure to selectively convert aminoheterocycles to their hydroxylated analogues by means of a simple pyrylium tetrafluoroborate salt. The hydroxylation step relies on a Lossen-type rearrangement under mild conditions thus avoiding the use of strong hydroxide bases. In addition to biorelevant heterocycles, the deaminative hydroxylation of electron-deficient anilines was also demonstrated. Finally, mechanistic experiments allowed the identification of the key intermediates, thus unveiling a rather unusual mechanism for this formal aromatic substitution.

Simultaneous determination of cordycepin and its metabolite 3'-deoxyinosine in rat whole blood by ultra-high-performance liquid chromatography coupled with Q Exactive hybrid quadrupole orbitrap high-resolution accurate mass spectrometry and its application to accurate pharmacokinetic studies

Cordycepin from Cordyceps possesses excellent pharmacological properties, including anti-inflammation and anti-tumor effects, therefore representing a potential alternative medicine. However, doubts about the pharmacokinetic results of cordycepin had been raised in the previous study due to its rapid deamination. The organic solvent methanol was immediately added to terminate the degradation of cordycepin in anticoagulated blood samples and enable the accurate evaluation of pharmacokinetics in vivo. A sensitive and selective ultra-high-performance liquid chromatography coupled with Q Exactive hybrid quadrupole orbitrap high-resolution accurate mass spectrometry method was developed and validated to simultaneously determine cordycepin and its deamination metabolite 3'-deoxyinosine using 2-chloroadenosine as an internal standard in rat whole blood. The calibration curves of cordycepin and 3'-deoxyinosine showed excellent linearity within the concentration range of 1.05-10 000.00 ng/ml with acceptable accuracy, precision, selectivity, recovery, matrix effect, and stability. This method was successfully applied to the pharmacokinetic study of cordycepin and its metabolite in rat blood. The effect of the adenosine deaminase inhibitor erythro-9-(2-hydroxy-3-nonyl) adenine hydrochloride on the pharmacokinetics of cordycepin was investigated. In summary, the reliable pharmacokinetic parameters of cordycepin and its deamination metabolite 3'-deoxyinosine in rat blood were successfully elucidated. Erythro-9-(2-hydroxy-3-nonyl) adenine hydrochloride considerably prolonged the half-life of cordycepin in vivo.

The Role of Reduced Glutathione on the Activity of Adenosine Deaminase, Antioxidative System, and Aluminum and Zinc Levels in Experimental Aluminum Toxicity

Aluminum (Al) is one of the most abundant element in the world. But aluminum exposure and accumulation causes serious diseases, related with free radicals. Reduced glutathione (GSH) is a tripeptide with intracellular antioxidant effects. This study aimed to investigate the role of GSH on adenosine deaminase (ADA), antioxidant system, and aluminum and zinc (Zn) levels in acute aluminum toxicity. In this study, Sprague-Dawley rats (n = 32) were used. The rats were divided into four equal groups (n = 8). Group I received 0.5 mL intraperitoneal injection of 0.9% saline solution (NaCI), Group II received single-dose AlCI₃, Group III was given GSH for seven days, and Group IV was given AlCI₃ single dose, and at the same time, 100 mg/kg GSH was given for seven days. At the end of the trial, blood samples were collected by cardiac puncture. Serum total antioxidant status (TAS) and Zn levels were lower in the aluminum-administered group than the control group. In contrast, plasma total oxidant status (TOS) and aluminum concentrations and ADA activity were found higher in the aluminum-administered group than in the control group. Unlike the other groups, group GSH administrated with aluminum was similar to the control group. As a result, GSH administration has a regulatory effect on ADA activity, antioxidant system, and Zn levels in experimental aluminum toxicity. In addition, GSH may reduce the oxidant capacity increased by Al administration and may have a tolerant role on the accumulated serum Al levels. But long-term experimental Al toxicity studies are needed to reach a firm conclusion.

Ambient air pollution and inflammation-related proteins during early childhood

BACKGROUND AND AIM

Experimental studies show that short-term exposure to air pollution may alter cytokine concentrations. There is, however, a lack of epidemiological studies evaluating the association between long-term air pollution exposure and inflammation-related proteins in young children. Our objective was to examine whether air pollution exposure is associated with inflammation-related proteins during the first 2 years of life.

METHODS

In a pooled analysis of two birth cohorts from Stockholm County (n = 158), plasma levels of 92 systemic inflammation-related proteins were measured by Olink Proseek Multiplex Inflammation panel at 6 months, 1 year and 2 years of age. Time-weighted average exposure to particles with an aerodynamic diameter of <10 μm (PM₁₀), <2.5 μm (PM_2.5), and nitrogen dioxide (NO₂) at residential addresses from birth and onwards was estimated via validated dispersion models. Stratified by sex, longitudinal cross-referenced mixed effect models were applied to estimate the overall effect of preceding air pollution exposure on combined protein levels, "inflammatory proteome", over the first 2 years of life, followed by cross-sectional protein-specific bootstrapped quantile regression analysis.

RESULTS

We identified significant longitudinal associations of inflammatory proteome during the first 2 years of life with preceding PM_2.5 exposure, while consistent associations with PM₁₀ and NO₂ across ages were only observed among girls. Subsequent protein-specific analyses revealed significant associations of PM₁₀ exposure with an increase in IFN-gamma and IL-12B in boys, and a decrease in IL-8 in girls at different percentiles of proteins levels, at age 6 months. Several inflammation-related proteins were also significantly associated with preceding PM₁₀, PM_2.5 and NO₂ exposures, at ages 1 and 2 years, in a sex-specific manner.

CONCLUSIONS

Ambient air pollution exposure influences inflammation-related protein levels already during early childhood. Our results also suggest age- and sex-specific differences in the impact of air pollution on children's inflammatory profiles.

Real-world effectiveness and protection of SARS-CoV-2 vaccine among patients hospitalized for COVID-19 in Xi'an, China, December 8, 2021, to January 20, 2022: A retrospective study

Introduction

In December 2021, a large-scale epidemic broke out in Xi'an, China, due to SARS-CoV-2 infection. This study reports the effect of vaccination on COVID-19 and evaluates the impact of different vaccine doses on routine laboratory markers.

Methods

The laboratory data upon admission, of 231 cases with COVID-19 hospitalized from December 8, 2021 to January 20, 2022 in Xi'an, including blood routine, lymphocyte subtypes, coagulative function tests, virus specific antibodies and blood biochemical tests were collected and analyzed.

Results

Of the 231 patients, 21 were not vaccinated, 158 were vaccinated with two doses and 52 with three doses. Unvaccinated patients had a higher proportion of moderate and severe symptoms than vaccinated patients, while two-dose vaccinated patients had a higher proportion than three-dose vaccinated patients. SARS-CoV-2 specific IgG levels were significantly elevated in vaccinated patients compared with unvaccinated patients. Particularly, unvaccinated patients had lower counts and percentages of lymphocytes, eosinophils and CD8+ T-lymphocytes, and elevated coagulation-related markers. In addition, vaccination had no effect on liver and kidney function.

Conclusions

Vaccination against SARS-CoV-2, inducing high IgG level and increased CD8+ T cells and eosinophils, and regulating coagulation function, can significantly attenuate symptoms of COVID-19, suggesting that the vaccine remains protective against SARS-CoV-2.

Diagnostic performance of adenosine deaminase for abdominal tuberculosis: A systematic review and meta-analysis

Background and aim

Abdominal tuberculosis (TB) is a common type of extrapulmonary TB with an insidious onset and non-specific symptoms. Adenosine deaminase (ADA) levels increase rapidly in the early stages of abdominal TB. However, it remains unclear whether ADA serves as a diagnostic marker for abdominal TB.

Methods

We performed a systematic literature search for relevant articles published in PubMed, Web of Science, Cochrane Library, and Embase up to April 2022. First, we used the Quality Assessment of Diagnostic Accuracy Studies tool-2 (QUADAS-2), to evaluate the quality of the included articles. Bivariate and hierarchical summary receiver operating characteristic (HSROC) models were then utilized to analyze pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and area under the receiver operating characteristic curve (AUROC). In addition, we explored a subgroup analysis for potential heterogeneity and publication bias among the included literature.

Results

Twenty-four articles (3,044 participants, 3,044 samples) which met the eligibility criteria were included in this study. The pooled sensitivity and specificity of ADA for abdominal TB detection were 93% [95% confidence interval (CI): 0.89-0.95] and 95% (95% CI: 0.93-0.96), respectively. PLR and NLR were 18.6 (95% CI: 14.0-24.6) and 0.08 (95% CI: 0.05-0.12), respectively. DOR and AUROC were 236 (95% CI: 134-415) and 0.98 (95% CI: 0.96-0.99), respectively. Furthermore, no heterogeneity or publication bias was found.

Conclusions

Our meta-analysis found ADA to be of excellent diagnostic value for abdominal TB and could be used as an auxiliary diagnostic tool.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42022297931.

Dipeptidyl Peptidase 4 (DPP4) as A Novel Adipokine: Role in Metabolism and Fat Homeostasis

Dipeptidyl peptidase 4 (DPP4) is a molecule implicated in the regulation of metabolic homeostasis and inflammatory processes, and it exerts its main action through its enzymatic activity. DPP4 represents the enzyme most involved in the catabolism of incretin hormones; thus, its activity impacts appetite, energy balance, and the fine regulation of glucose homeostasis. Indeed, DPP4 inhibitors represent a class of antidiabetic agents widely used for the treatment of Type 2 diabetes mellitus (T2DM). DPP4 also acts as an adipokine and is mainly secreted by the adipose tissue, mostly from mature adipocytes of the visceral compartment, where it exerts autocrine and paracrine activities. DPP4 can disrupt insulin signaling within the adipocyte and in other target cells and tissues, where it also favors the development of a proinflammatory environment. This is likely at the basis of the presence of elevated circulating DPP4 levels in several metabolic diseases. In this review, we summarize the most recent evidence of the role of the DPP4 as an adipokine-regulating glucose/insulin metabolism and fat homeostasis, with a particular focus on clinical outcomes associated with its increased secretion in the presence of adipose tissue accumulation and dysfunction.

The regulatory mechanism and potential application of IL-23 in autoimmune diseases

IL-23 is a heterodimeric pro-inflammatory cytokine secreted by dendritic cells and macrophages that belongs to the IL-12 family. It has pro-inflammatory effects and is a key cytokine and upstream regulatory cytokine involved in protective immune responses, stimulating the differentiation and proliferation of downstream effectors such as Th17 cells. It is expressed in various autoimmune diseases such as psoriasis, systemic lupus erythematosus (SLE), rheumatoid arthritis (RA). The IL-23/TH17 axis formed by IL-23 and TH17 has been confirmed to participate in autoimmune diseases pathogenesis. IL-23R is the receptor for IL-23 and plays an activating role. Targeting IL-23 is currently the main strategy for the treatment of various autoimmune diseases. In this review we summarized the mechanism of action and clinical application potential of IL-23 in autoimmune diseases by summarizing the latest research results and reviewing the literature, which would help to further understand IL-23 and provide a theoretical basis for future clinical targeting and drug development.

Identification and Functional Characterization of Adenosine Deaminase in Mucor circinelloides: A Novel Potential Regulator of Nitrogen Utilization and Lipid Biosynthesis

Adenosine deaminase (ADA) is an enzyme distributed in a wide variety of organisms that cleaves adenosine into inosine. Since inosine plays an important role in nitrogen metabolism, ADA may have a critical function in the regulation of fatty acid synthesis. However, the role of ADA in oleaginous fungi has not been reported so far. Therefore, in this study, we identified one ada gene encoding ADA (with ID scaffold0027.9) in the high lipid-producing fungus, Mucor circinelloides WJ11, and investigated its role in cell growth, lipid production, and nitrogen metabolism by overexpressing and knockout of this gene. The results showed that knockout of the ada altered the efficiency of nitrogen consumption, which led to a 20% increment in the lipid content (25% of cell dry weight) of the engineered strain, while overexpression of the ada showed no significant differences compared with the control strain at the final growth stage; however, interestingly, it increased lipid accumulation at the early growth stage. Additionally, transcriptional analysis was conducted by RT-qPCR and our findings indicated that the deletion of ada activated the committed steps of lipid biosynthesis involved in acetyl-CoA carboxylase (acc1 gene), cytosolic malic acid enzyme (cme1 gene), and fatty acid synthases (fas1 gene), while it suppressed the expression of AMP-activated protein kinase (ampk α1 and ampk β genes), which plays a role in lipolysis, whereas the ada-overexpressed strain displayed reverse trends. Conclusively, this work unraveled a novel role of ADA in governing lipid biosynthesis and nitrogen metabolism in the oleaginous fungus, M. circinelloides.

Emerging role of the cGAS-STING signaling pathway in autoimmune diseases: Biologic function, mechanisms and clinical prospection

The cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) signaling pathway, as vital component of innate immune system, acts a vital role in distinguishing invasive pathogens and cytosolic DNA. Cytosolic DNA sensor cGAS first binds to cytosolic DNA and catalyze synthesis of cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), which is known as the secondmessenger. Next, cGAMP activates the adaptor protein STING, triggering a molecular chain reaction to stimulate cytokines including interferons (IFNs). Recently, many researches have revealed that the regulatory role of cGAS-STING signaling pathway in autoimmune diseases (AIDs) such as Rheumatoid arthritis (RA), Aicardi Goutières syndrome (AGS) and systemic lupus erythematosus (SLE). Moreover, accumulated evidence showed inhibition of the cGAS-STING signaling pathway can remarkably suppress joint swelling and inflammatory cell infiltration in RA mice. Therefore, in this review, we describe the molecular properties, biologic function and mechanisms of the cGAS-STING signaling pathway in AIDs. In addition, potential clinical applications especially selective small molecule inhibitors targeting the cGAS-STING signaling pathway are also discussed.

tiRNAs: Insights into Their Biogenesis, Functions, and Future Applications in Livestock Research

Transfer RNA (tRNA)-derived small RNAs (tsRNAs) belong to a group of transfer ribonucleic acid (tRNA)-derived fragments that have recently gained interest as molecules with specific biological functions. Their involvement in the regulation of physiological processes and pathological phenotypes suggests molecular roles similar to those of miRNAs. tsRNA biogenesis under specific physiological conditions will offer new perspectives in understanding diseases, and may provide new sources for biological marker design to determine and monitor the health status of farm animals. In this review, we focus on the latest discoveries about tsRNAs and give special attention to molecules initially thought to be mainly associated with tRNA-derived stress-induced RNAs (tiRNAs). We present an outline of their biological functions, offer a collection of useful databases, and discuss future research perspectives and applications in livestock basic and applied research.

Quercetin mitigates rheumatoid arthritis by inhibiting adenosine deaminase in rats

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease characterized by synovial proliferation and bone destruction. Adenosine deaminase (ADA) is a key inflammatory enzyme that increases joint stiffness and pain in RA. In this study, we evaluated the in-silico, and in vivo inhibitory effect of quercetin isolated from Egyptian Fenugreek on ADA enzyme activity. We also determined the combinatorial effect of quercetin on methotrexate mediated anti-inflammatory efficacy and toxicity. In-silico molecular docking was conducted and confirmed in an in vivo RA rat model. The results showed that the inhibition constant of quercetin on joint ADA by docking and in-vitro was 61.9 and 55.5 mM, respectively. Therefore, quercetin exhibits anti-inflammatory effect in a rat RA model as evidenced by reducing the specific activity of ADA in joint tissues, lower jaw volume, enhance body weight, downregulate ADA gene expression, reduce levels of RA cytokines interleukin-1^β, interleukin-6, tumor necrosis factor-α, also, rheumatoid factor, C-reactive protein, and anti-cyclic citrullinated peptide RA biomarker levels. These findings demonstrate that the purified quercetin has a promising anti-inflammatory effect against RA disease through its inhibitory effects on the ADA enzyme. Furthermore, isolated quercetin improved the anti-inflammatory efficacy of methotrexate, reduced its toxic effects by increasing antioxidant enzymes and reducing oxidative stress.

Increased serum adenosine deaminase activity in patients with adult-onset Still's disease

Background

Adult-onset Still's disease (AOSD) is a systemic inflammatory disease of unknown etiology, lacking specific diagnosis and disease activity evaluation indicators. This study will analyze the activity and clinical significance of Adenosine deaminase (ADA) in AOSD patients.

Methods

Totally 53 AOSD patients, 60 patients with other autoimmune diseases including systemic lupus erythematosus (SLE), sjogren syndrome (SS) and rheumatoid arthritis (RA), as well as 60 healthy subjects were included in this study. AOSD activity was determined by Pouchot score. We analyzed the correlation between ADA activity and clinical parameters. In addition, the correlation between ADA activity and disease activity score was also analyzed.

Results

This study showed that the activity of ADA in AOSD patients was significantly higher than that of healthy controls, SLE, SS and RA patient groups (p < 0.0001). The ADA activity of AOSD patients decreased significantly after systemic treatment (p < 0.0001). Correlation analysis showed that ADA activity was positively correlated with ALT(r = 0.54, p < 0.0001), AST (r = 0.82, p < 0.0001) and serum ferritin (r = 0.67, p < 0.001). ADA activity was negatively correlated with white blood cell (r = − 0.42, p = 0.002) and platelet counts (r = − 0.44, p = 0.001). We also found a significant positive correlation between the activity of ADA and Pouchot score in AOSD patients (r = 0.51, p = 0.001). Receiver operating characteristic (ROC) curve analysis showed that ADA activity had a sensitivity of 93.3%, and a specificity of 83% for the diagnosis of AOSD, with an area under the curve of 0.93.

Conclusion

This study showed that serum ADA activity can be used as a potential biomarker for AOSD diagnosis and disease activity assessment.

Increased levels of serum adenosine deaminase and increased risk of diabetic peripheral neuropathy in type 2 diabetes

BACKGROUND

Increased serum adenosine deaminase (ADA) levels have been shown to be involved in metabolic abnormalities and immune disequilibrium, which may in turn contribute to inflammatory diseases. This study aimed to determine whether increased serum ADA levels are related to diabetic peripheral neuropathy (DPN) in patients with type 2 diabetes (T2D).

METHODS

This study was part of a series exploring the potential risks for DPN. All patients received DPN assessment based on neuropathic symptoms, neuropathic signs, and nerve conduction studies to calculate the composite Z score of nerve latency, amplitude and conduction velocity (NCV). DPN was confirmed by both at least a presentation of neuropathic symptoms/signs and an abnormal nerve conduction index. Serum ADA levels were also synchronously detected.

RESULTS

A total of 384 eligible patients with T2D were recruited for this study, and 24.5% (n=94) were determined to have DPN. Increases in serum ADA levels were closely associated with increases in composite Z score of latency (β=0.263, t=5.273, p<0.001) and decreases in composite Z score of amplitude (β=-0.126, t=-2.352, p=0.019) and NCV (β=-0.201, t=-3.841, p<0.001) after adjusting for other clinical covariates. Moreover, each 5 U/L increase in serum ADA levels was associated with a 1.781-fold increased adjusted odds ratio of having DPN (95% confidence interval: 1.271-2.495). Furthermore, the optimal cut-off value of serum ADA levels to discriminate DPN was ≥14.2 U/L (sensitivity=59.57%, specificity=75.52% and Youden index=0.351) after analysis by receiver operating characteristic curve.

CONCLUSIONS

Increased serum ADA levels may be a potential risk factor for DPN in patients with T2D.

Nobel Prize for immune checkpoint inhibitors, understanding the immunological switching between immunosuppression and autoimmunity

INTRODUCTION

Immune checkpoint inhibitors (ICIs) are a revolutionary form of immunotherapy in cancer. However, the percentage of patients responding to therapy is relatively low, while adverse effects occur in a large number of patients. In addition, the therapeutic mechanisms of ICIs are not yet completely described.

AREAS COVERED

The initial view (articles published in PubMed, Scopus, Web of Science, etc.) was that ICIs increase tumor-specific immunity. Recent data (collected from the same databases) suggest that the ICIs pharmacotherapy actually extends beyond the topic of immune reactivity, including additional immune pathways, such as disrupting immunosuppression and increasing tumor-specific autoimmunity. Unfortunately, there is no clear delimitation between these specific autoimmune reactions that are therapeutically beneficial, and nonspecific autoimmune reactions/toxicity that can be extremely severe side effects.

EXPERT OPINION

Immune checkpoint mechanisms perform a non-selective immune regulation, maintaining a dynamic balance between immunosuppression and autoimmunity. By blocking these mechanisms, ICIs actually perform an immunological reset, decreasing immunosuppression and increasing tumor-specific immunity and predisposition to autoimmunity. The predisposition to autoimmunity induces both side effects and beneficial autoimmunity. Consequently, further studies are necessary to maximize the beneficial tumor-specific autoimmunity, while reducing the counterproductive effect of associated autoimmune toxicity.

Deciphering the tRNA-derived small RNAs: origin, development, and future

Transfer RNA (tRNA)-derived small RNAs (tsRNAs), a novel category of small noncoding RNAs, are enzymatically cleaved from tRNAs. Previous reports have shed some light on the roles of tsRNAs in the development of human diseases. However, our knowledge about tsRNAs is still relatively lacking. In this paper, we review the biogenesis, classification, subcellular localization as well as action mechanism of tsRNAs, and discuss the association between chemical modifications of tRNAs and the production and functions of tsRNAs. Furthermore, using immunity, metabolism, and malignancy as examples, we summarize the molecular mechanisms of tsRNAs in diseases and evaluate the potential of tsRNAs as new biomarkers and therapeutic targets. At the same time, we compile and introduce several resource databases that are currently publicly available for analyzing tsRNAs. Finally, we discuss the challenges associated with research in this field and future directions.

Zinc enzymes in medicinal chemistry

In humans, more than three hundred diverse enzymes that require zinc as an essential cofactor have been identified. These zinc enzymes have demonstrated different and important physiological functions and some of them have been considered as valuable therapeutic targets for drug discovery. Indeed, many drugs targeting a few zinc enzymes have been marketed to treat a variety of diseases. This review discusses drug discovery and drug development based on a dozen of zinc enzymes, including their biological functions and pathogenic roles, their best in class inhibitors (and clinical trial data when available), coordination and binding modes of representative inhibitors, and their implications for further drug design. The opportunities and challenges in developing zinc enzyme inhibitors for the treatment of human disorders are highlighted, too.

ANA positivity and complement level in pleural fluid are potential diagnostic markers in discriminating lupus pleuritis from pleural effusion of other aetiologies

OBJECTIVE

Lupus pleuritis is the most common pulmonary manifestation of systemic lupus erythematosus (SLE). We aimed to compare various biomarkers in discriminating between pleural effusions due to lupus pleuritis and other aetiologies.

METHODS

We determined in 59 patients (16 patients with SLE and 43 patients without SLE) pleural fluid levels of high-mobility group box 1, soluble receptor for advanced glycation end products (sRAGE), adenosine deaminase (ADA), interleukin (IL) 17A, tumour necrosis factor-α, antinuclear antibodies (ANA), and complements C3 and C4.

RESULTS

We found significant differences in the pleural fluid level of sRAGE, ADA, IL-17A, C3 and C4, and in the proportion of ANA positivity, among lupus pleuritis and other groups with pleural effusion. Specifically, ANA positivity (titre ≥1: 80) achieved a high sensitivity of 91%, specificity of 83% and negative predictive value (NPV) of 97% in discriminating lupus pleuritis from non-lupus pleural effusion. A parallel combination of the level of C3 (<24 mg/dL) and C4 (<3 mg/dL) achieved a sensitivity of 82%, specificity of 89% and NPV of 93% in discriminating lupus pleuritis from non-lupus exudative pleural effusion.

CONCLUSIONS

In conclusion, ANA, C3 and C4 in pleural fluid are useful in discriminating lupus pleuritis from pleural effusion due to other aetiologies with high NPV.

The Pathological Mechanism and Potential Application of IL-38 in Autoimmune Diseases

Interleukin-38 (IL-38), a new cytokine of interleukin-1 family (IL-1F), is expressed in the human heart, kidney, skin, etc. Recently, new evidence indicated that IL-38 is involved in the process of different autoimmune diseases. Autoimmune diseases are a cluster of diseases accompanied with tissue damage caused by autoimmune reactions, including rheumatoid arthritis (RA), psoriasis, etc. This review summarized the links between IL-38 and autoimmune diseases, as well as the latest knowledge about the function and regulatory mechanism of IL-38 in autoimmune diseases. Especially, this review focused on the differentiation of immune cells and explore future prospects, such as the application of IL-38 in new technologies. Understanding the function of IL-38 is helpful to shed light on the progress of autoimmune diseases.