Group II metabotropic glutamate receptor activation attenuates acid-sensing ion channel currents in rat primary sensory neurons.

Acid-sensing ion channels (ASICs) play an important role in pain associated with tissue acidification. Peripheral inhibitory group II metabotropic glutamate receptors (mGluRs) have analgesic effects in a variety of pain conditions. Whether there is a link between ASICs and mGluRs in pain processes is still unclear. Herein, we show that the group II mGluR agonist LY354740 inhibited acid-evoked ASIC currents and action potentials in rat dorsal root ganglia neurons. LY354740 reduced the maximum current response to protons, but it did not change the sensitivity of ASICs to protons. LY354740 inhibited ASIC currents by activating group II mGluRs. We found that the inhibitory effect of LY354740 was blocked by intracellular application of the Gi/o protein inhibitor pertussis toxin and the cAMP analogue 8-Br-cAMP and mimicked by the protein kinase A (PKA) inhibitor H-89. LY354740 also inhibited ASIC3 currents in CHO cells coexpressing mGluR2 and ASIC3 but not in cells expressing ASIC3 alone. In addition, intraplantar injection of LY354740 dose-dependently alleviated acid-induced nociceptive behavior in rats through local group II mGluRs. Together, these results suggested that activation of peripheral group II mGluRs inhibited the functional activity of ASICs through a mechanism that depended on Gi/o proteins and the intracellular cAMP/PKA signaling pathway in rat dorsal root ganglia neurons. We propose that peripheral group II mGluRs are an important therapeutic target for ASIC-mediated pain.

Lipid mediator resolvin D2 inhibits ATP currents in rat primary sensory neurons.

Resolvin D2 (RvD2), an endogenous lipid mediator derived from docosahexaenoic acid, has been demonstrated to have analgesic effects. However, little is known about the mechanism underlying RvD2 in pain relief. Herein, we demonstrate that RvD2 targeted the P2X3 receptor as an analgesic. The electrophysiological activity of P2X3 receptors was suppressed by RvD2 in rat dorsal root ganglia (DRG) neurons. RvD2 pre-application dose-dependently decreased α,ß-methylene-ATP (α,ß-meATP)-induced inward currents. RvD2 remarkably decreased the maximum response to α,ß-meATP, without influencing the affinity of P2X3 receptors. RvD2 also voltage-independently suppressed ATP currents. An antagonist of the G protein receptor 18 (GPR18), O-1918, prevented the RvD2-induced suppression of ATP currents. Additionally, intracellular dialysis of the Gαi/o -protein antagonist pertussis toxin (PTX), the PKA antagonist H89, or the cAMP analog 8-Br-cAMP also blocked the RvD2-induced suppression. Furthermore, α,ß-meATP-triggered depolarization of membrane potential along with the action potential bursts in DRG neurons were inhibited by RvD2. Lastly, RvD2 attenuated spontaneous nociceptive behaviors as well as mechanical allodynia produced by α,ß-meATP in rats via the activation of the peripheral GPR18. These findings indicated that RvD2 inhibited P2X3 receptors in rat primary sensory neurons through GPR18, PTX-sensitive Gαi/o -proteins, and intracellular cAMP/PKA signaling, revealing a novel mechanism that underlies its analgesic effects by targeting P2X3 receptors.

Deep stratification by transcriptome molecular characters for precision treatment of patients with systemic lupus erythematosus.

OBJECTIVES: To leverage the high clinical heterogeneity of systemic lupus erythematosus (SLE), we developed and validated a new stratification scheme by integrating genome-scale transcriptomic profiles to identify patient subtypes sharing similar transcriptomic markers and drug targets. METHODS: A normalized compendium of transcription profiles was created from peripheral blood mononuclear cells (PBMCs) of 1046 SLE patients and 86 healthy controls (HCs), covering an intersection of 13 689 genes from six microarray datasets. Upregulated differentially expressed genes were subjected to functional and network analysis in which samples were grouped using unsupervised clustering to identify patient subtypes. Then, clustering stability was evaluated by the stratification of six integrated RNA-sequencing datasets using the same method. Finally, the Xgboost classifier was applied to the independent datasets to identify factors associated with treatment outcomes. RESULTS: Based on 278 upregulated DEGs of the transcript profiles, SLE patients were classified into three subtypes (subtype A-C) each with distinct molecular and cellular signatures. Neutrophil activation-related pathways were markedly activated in subtype A (named NE-driving), whereas lymphocyte and IFN-related pathways were more enriched in subtype B (IFN-driving). As the most severe subtype, subtype C [NE-IFN-dual-driving (Dual-driving)] shared functional mechanisms with both NE-driving and IFN-driving, which was closely associated with clinical features and could be used to predict the responses of treatment. CONCLUSION: We developed the largest cohesive SLE transcriptomic compendium for deep stratification using the most comprehensive microarray and RNA sequencing datasets to date. This result could guide future design of molecular diagnosis and the development of stratified therapy for SLE patients.

Potentiation of ASIC currents by lysophosphatidic acid in rat dorsal root ganglion neurons.

Lysophosphatidic acid (LPA) is a phospholipid which has been implicated in pain. Acid-sensing ion channels (ASICs) are important players in pain associated with tissue acidification. However, it is still unclear whether there is a link between LPA signaling and ASICs in pain processes. Herein, we show that a functional interaction between them in rat dorsal root ganglia (DRG) neurons. Pre-application of LPA enhanced ASIC-mediated and acid-evoked inward currents in a concentration-dependent manner. LPA shifted the concentration-response curve for protons upwards, with an increase of 41.79 ± 4.71% in the maximal current response of ASICs to protons in the presence of LPA. Potentiation of ASIC currents by LPA was blocked by the LPA1 receptor antagonist Ki16198, but not by the LPA2 receptor antagonist H2L5185303. The LPA-induced potentiation was also prevented by intracellular application of either G protein inhibitor or protein kinase C (PKC) inhibitor, but not by Rho inhibitor. LPA also enhanced ASIC3 currents in CHO cells co-expressing ASIC3 and LPA1 receptors, but not in cells expressing ASIC3 alone. Moreover, LPA increased the amplitude of the depolarization and the number of spikes induced by acid stimuli. Finally, LPA exacerbated acid-induced nociceptive behaviors in rats. These results suggested that LPA enhanced ASIC-mediated electrophysiological activity and nociception via a LPA1 receptor and its downstream PKC rather than Rho signaling pathway, which provided a novel peripheral mechanism underlying the sensitization of pain.

Deciphering the molecular landscape of rheumatoid arthritis offers new insights into the stratified treatment for the condition.

Background: For Rheumatoid Arthritis (RA), a long-term chronic illness, it is essential to identify and describe patient subtypes with comparable goal status and molecular biomarkers. This study aims to develop and validate a new subtyping scheme that integrates genome-scale transcriptomic profiles of RA peripheral blood genes, providing a fresh perspective for stratified treatments. Methods: We utilized independent microarray datasets of RA peripheral blood mononuclear cells (PBMCs). Up-regulated differentially expressed genes (DEGs) were subjected to functional enrichment analysis. Unsupervised cluster analysis was then employed to identify RA peripheral blood gene expression-driven subtypes. We defined three distinct clustering subtypes based on the identified 404 up-regulated DEGs. Results: Subtype A, named NE-driving, was enriched in pathways related to neutrophil activation and responses to bacteria. Subtype B, termed interferon-driving (IFN-driving), exhibited abundant B cells and showed increased expression of transcripts involved in IFN signaling and defense responses to viruses. In Subtype C, an enrichment of CD8+ T-cells was found, ultimately defining it as CD8+ T-cells-driving. The RA subtyping scheme was validated using the XGBoost machine learning algorithm. We also evaluated the therapeutic outcomes of biological disease-modifying anti-rheumatic drugs. Conclusions: The findings provide valuable insights for deep stratification, enabling the design of molecular diagnosis and serving as a reference for stratified therapy in RA patients in the future.

Quantitative radiomics analysis of imaging features in adults and children Mycoplasma pneumonia.

Purpose: This study aims to explore the value of clinical features, CT imaging signs, and radiomics features in differentiating between adults and children with Mycoplasma pneumonia and seeking quantitative radiomic representations of CT imaging signs. Materials and methods: In a retrospective analysis of 981 cases of mycoplasmal pneumonia patients from November 2021 to December 2023, 590 internal data (adults:450, children: 140) randomly divided into a training set and a validation set with an 8:2 ratio and 391 external test data (adults:121; children:270) were included. Using univariate analysis, CT imaging signs and clinical features with significant differences (p < 0.05) were selected. After segmenting the lesion area on the CT image as the region of interest, 1,904 radiomic features were extracted. Then, Pearson correlation analysis (PCC) and the least absolute shrinkage and selection operator (LASSO) were used to select the radiomic features. Based on the selected features, multivariable logistic regression analysis was used to establish the clinical model, CT image model, radiomic model, and combined model. The predictive performance of each model was evaluated using ROC curves, AUC, sensitivity, specificity, accuracy, and precision. The AUC between each model was compared using the Delong test. Importantly, the radiomics features and quantitative and qualitative CT image features were analyzed using Pearson correlation analysis and analysis of variance, respectively. Results: For the individual model, the radiomics model, which was built using 45 selected features, achieved the highest AUCs in the training set, validation set, and external test set, which were 0.995 (0.992, 0.998), 0.952 (0.921, 0.978), and 0.969 (0.953, 0.982), respectively. In all models, the combined model achieved the highest AUCs, which were 0.996 (0.993, 0.998), 0.972 (0.942, 0.995), and 0.986 (0.976, 0.993) in the training set, validation set, and test set, respectively. In addition, we selected 11 radiomics features and CT image features with a correlation coefficient r greater than 0.35. Conclusion: The combined model has good diagnostic performance for differentiating between adults and children with mycoplasmal pneumonia, and different CT imaging signs are quantitatively represented by radiomics.

A Compendium of Mucosal Molecular Characteristics Provides Novel Perspectives on the Treatment of Ulcerative Colitis.

BACKGROUND AND AIMS: Ulcerative colitis [UC] is a complex heterogeneous disease. This study aims to reveal the underlying molecular features of UC using genome-scale transcriptomes of patients with UC, and to develop and validate a novel stratification scheme. METHODS: A normalised compendium was created using colon tissue samples (455 patients with UC and 147 healthy controls [HCs]), covering genes from 10 microarray datasets. Upregulated differentially expressed genes [DEGs] were subjected to functional network analysis, wherein samples were grouped using unsupervised clustering. Additionally, the robustness of subclustering was further assessed by two RNA sequencing datasets [100 patients with UC and 16 HCs]. Finally, the Xgboost classifier was applied to the independent datasets to evaluate the efficacy of different biologics in patients with UC. RESULTS: Based on 267 upregulated DEGs of the transcript profiles, UC patients were classified into three subtypes [subtypes A-C] with distinct molecular and cellular signatures. Epithelial activation-related pathways were significantly enriched in subtype A [named epithelial proliferation], whereas subtype C was characterised as the immune activation subtype with prominent immune cells and proinflammatory signatures. Subtype B [named mixed] was modestly activated in all the signalling pathways. Notably, subtype A showed a stronger association with the superior response of biologics such as golimumab, infliximab, vedolizumab, and ustekinumab compared with subtype C. CONCLUSIONS: We conducted a deep stratification of mucosal tissue using the most comprehensive microarray and RNA sequencing data, providing critical insights into pathophysiological features of UC, which could serve as a template for stratified treatment approaches.

Group II metabotropic glutamate receptor activation suppresses ATP currents in rat dorsal root ganglion neurons.

P2X3 receptors and group II metabotropic glutamate receptors (mGluRs) have been found to be expressed in primary sensory neurons. P2X3 receptors participate in a variety of pain processes, while the activation of mGluRs has an analgesic effect. However, it's still unclear whether there is a link between them in pain. Herein, we reported that the group II mGluR activation inhibited the electrophysiological activity of P2X3 receptors in rat dorsal root ganglia (DRG) neurons. Group II mGluR agonist LY354740 concentration-dependently decreased P2X3 receptor-mediated and α,ß-methylene-ATP (α,ß-meATP)-evoked inward currents in DRG neurons. LY354740 significantly suppressed the maximum response of P2X3 receptor to α,ß-meATP, but did not change their affinity. Inhibition of ATP currents by LY354740 was blocked by the group II mGluR antagonist LY341495, also prevented by the intracellular dialysis of either the Gi/o protein inhibitor pertussis toxin, the cAMP analog 8-Br-cAMP, or the protein kinase A (PKA) inhibitor H-89. Moreover, LY354740 decreased α,ß-meATP-induced membrane potential depolarization and action potential bursts in DRG neurons. Finally, intraplantar injection of LY354740 also relieved α,ß-meATP-induced spontaneous nociceptive behaviors and mechanical allodynia in rats by activating peripheral group Ⅱ mGluRs. These results indicated that peripheral group II mGluR activation inhibited the functional activity of P2X3 receptors via a Gi/o protein and cAMP/PKA signaling pathway in rat DRG neurons, which revealed a novel mechanism underlying analgesic effects of peripheral group II mGluRs. This article is part of the Special Issue on "Purinergic Signaling: 50 years".

Enhancement of P2X3 Receptor-Mediated Currents by Lysophosphatidic Acid in Rat Primary Sensory Neurons.

Lysophosphatidic acid (LPA), a lipid metabolite, plays a role in both neuropathic and inflammatory pain through LPA1 receptors. P2X3 receptor has also been shown to participate in these pathological processes. However, it is still unclear whether there is a link between LPA signaling and P2X3 receptors in pain. Herein, we show that a functional interaction between them in rat dorsal root ganglia (DRG) neurons. Pretreatment of LPA concentration-dependently enhanced α,ß-methylene-ATP (α,ß-meATP)-induced inward currents mediated by P2X3 receptors. LPA significantly increased the maximal current response of α,ß-meATP, showing an upward shift of the concentration-response curve for α,ß-meATP. The LPA enhancement was independent on the clamping-voltage. Enhancement of P2X3 receptor-mediated currents by LPA was prevented by the LPA1 receptor antagonist Ki16198, but not by the LPA2 receptor antagonist H2L5185303. The LPA-induced potentiation was also attenuated by intracellular dialysis of either G-protein inhibitor or protein kinase C (PKC) inhibitor, but not by Rho inhibitor. Moreover, LPA significantly changed the membrane potential depolarization and action potential burst induced by α,ß-meATP in DRG neurons. Finally, LPA exacerbated α,ß-meATP- induced nociceptive behaviors in rats. These results suggested that LPA potentiated the functional activity of P2X3 receptors in rat primary sensory neurons through activation of the LPA1 receptor and its downstream PKC rather than Rho signaling pathway, indicating a novel peripheral mechanism underlying the sensitization of pain.

Suppression of P2X3 receptor-mediated currents by the activation of α2A -adrenergic receptors in rat dorsal root ganglion neurons.

AIMS: The α2 -adrenergic receptor (α2 -AR) agonists have been shown to be effective in the treatment of various pain. For example, dexmedetomidine (DEX), a selective α2A -AR agonist, can be used for peripheral analgesia. However, it is not yet fully elucidated for the precise molecular mechanisms. P2X3 receptor is a major receptor processing nociceptive information in primary sensory neurons. Herein, we show that a functional interaction of α2A -ARs and P2X3 receptors in dorsal root ganglia (DRG) neurons could contribute to peripheral analgesia of DEX. METHODS: Electrophysiological recordings were carried out on rat DRG neurons, and nociceptive behavior was quantified in rats. RESULTS: The activation of α2A -ARs by DEX suppressed P2X3 receptor-mediated and α,ß-methylene-ATP (α,ß-meATP)-evoked inward currents in a concentration-dependent and voltage-independent manner. Pre-application of DEX shifted the α,ß-meATP concentration-response curve downwards, with a decrease of 50.43 ± 4.75% in the maximal current response of P2X3 receptors to α,ß-meATP in the presence of DEX. Suppression of α,ß-meATP-evoked currents by DEX was blocked by the α2A -AR antagonist BRL44408 and prevented by intracellular application of the Gi/o protein inhibitor pertussis toxin, the adenylate cyclase activator forskolin, and the cAMP analog 8-Br-cAMP. DEX also suppressed α,ß-meATP-evoked action potentials through α2A -ARs in rat DRG neurons. Finally, the activation of peripheral α2A -ARs by DEX had an analgesic effect on the α,ß-meATP-induced nociception. CONCLUSIONS: These results suggested that activation of α2A -ARs by DEX suppressed P2X3 receptor-mediated electrophysiological and behavioral activity via a Gi/o proteins and cAMP signaling pathway, which was a novel potential mechanism underlying analgesia of peripheral α2A -AR agonists.

Suppression of ASIC activity by the activation of A1 adenosine receptors in rat primary sensory neurons.

Peripheral A1 adenosine receptor signaling has been shown to have analgesic effects in a variety of pain conditions. However, it is not yet fully elucidated for the precise molecular mechanisms. Acid sensing ion channels (ASICs) are expressed predominantly in nociceptive sensory neurons responding to protons. Given that both A1 adenosine receptors and ASICs are present in dorsal root ganglia (DRG) neurons, we therefore investigated whether there was a cross-talk between the two types of receptors. Herein, electrophysiological recordings showed that the A1 adenosine receptor agonist N6-cyclopentyladenosine (CPA) suppressed acid-induced currents and action potentials, which were mediated by ASICs, in rat DRG neurons. CPA inhibited the maximum response to protons, as shown a downward shift of concentration-response curve for protons. The CPA-induced suppression of ASIC currents was blocked by the A1 adenosine receptor antagonist KW-3902 and also prevented by intracellular application of the Gi/o-protein inhibitor pertussis toxin, the adenylate cyclase activator forskolin, and the cAMP analog 8-Br-cAMP. Finally, intraplantar pretreatment of CPA dose-dependently relieved acid-induced nociceptive responses in rats through peripheral A1 adenosine receptors. These results suggested that CPA suppressed ASICs via A1 adenosine receptors and intracellular Gi/o-proteins and cAMP signaling cascades in rat DRG neurons, which was a novel potential mechanism underlying analgesia of peripheral A1 adenosine receptors.

A1 Adenosine Receptor Activation Inhibits P2X3 Receptor-Mediated ATP Currents in Rat Dorsal Root Ganglion Neurons.

Purinergic signaling is involved in multiple pain processes. P2X3 receptor is a key target in pain therapeutics, while A1 adenosine receptor signaling plays a role in analgesia. However, it remains unclear whether there is a link between them in pain. The present results showed that the A1 adenosine receptor agonist N6-cyclopentyladenosine (CPA) concentration dependently suppressed P2X3 receptor-mediated and α,ß-methylene-ATP (α,ß-meATP)-evoked inward currents in rat dorsal root ganglion (DRG) neurons. CPA significantly decreased the maximal current response to α,ß-meATP, as shown a downward shift of the concentration-response curve for α,ß-meATP. CPA suppressed ATP currents in a voltage-independent manner. Inhibition of ATP currents by CPA was completely prevented by the A1 adenosine receptor antagonist KW-3902, and disappeared after the intracellular dialysis of either the Gi/o protein inhibitor pertussis toxin, the adenylate cyclase activator forskolin, or the cAMP analog 8-Br-cAMP. Moreover, CPA suppressed the membrane potential depolarization and action potential bursts, which were induced by α,ß-meATP in DRG neurons. Finally, CPA relieved α,ß-meATP-induced nociceptive behaviors in rats by activating peripheral A1 adenosine receptors. These results indicated that CPA inhibited the activity of P2X3 receptors in rat primary sensory neurons by activating A1 adenosine receptors and its downstream cAMP signaling pathway, revealing a novel peripheral mechanism underlying its analgesic effect.

An updated analysis of the association between CD2-associated protein gene rs9349407 polymorphism and Alzheimer's disease in Chinese population.

Background: Since 2011, three large-scale genome-wide association studies (GWAS) have confirmed that the CD2AP rs9349407 polymorphism is significantly connected with Alzheimer's disease (AD) in individuals of European descent. Subsequently, this association has been replicated in European populations, but is unclear whether it can be replicated in Chinese. Recently, the correlation between rs9349407 and AD in the Chinese population has become a research hotspot. Objective: To explore the association between rs9349407 polymorphism and AD in the Chinese population. Materials and methods: Firstly, based on the exclusion and inclusion criteria, we selected 11 independent studies from 8 articles exploring the correlation between rs9349407 variation and AD in Chinese. Secondly, we conducted a meta-analysis based on fixed and random effect models and conducted a heterogeneity test. Thirdly, we used the additive model, dominant model, and recessive model for subgroup analysis. Results: We demonstrated that the CD2AP rs9349407 polymorphism increases AD susceptibility in Chinese populations (OR = 1.33, 95% CI = 1.08-1.64, P = 7.45E-03), which is consistent with the effect observed in Caucasian populations. Additionally, subgroup analysis showed that rs9349407 under the additive model (GG + CC vs. GC, OR = 0.76, 95% CI = 0.61-0.97, P = 2.04E-02) and dominant model (GG + GC vs. CC, OR = 0.49, 95% CI = 0.32-0.74, P = 8.51E-04) were also significantly correlated with AD susceptibility, but not under the recessive model (GG vs. GC + CC, OR = 0.77, 95% CI = 0.58-1.03, P = 7.44E-02). Conclusion: These existing data suggest that rs9349307 is significantly correlated with the susceptibility to AD in the Chinese population, but future studies with large samples are needed to confirm our findings.

Micropathogen Community Analysis in Hyalomma rufipes via High-Throughput Sequencing of Small RNAs.

Ticks are important vectors in the transmission of a broad range of micropathogens to vertebrates, including humans. Because of the role of ticks in disease transmission, identifying and characterizing the micropathogen profiles of tick populations have become increasingly important. The objective of this study was to survey the micropathogens of Hyalomma rufipes ticks. Illumina HiSeq2000 technology was utilized to perform deep sequencing of small RNAs (sRNAs) extracted from field-collected H. rufipes ticks in Gansu Province, China. The resultant sRNA library data revealed that the surveyed tick populations produced reads that were homologous to St. Croix River Virus (SCRV) sequences. We also observed many reads that were homologous to microbial and/or pathogenic isolates, including bacteria, protozoa, and fungi. As part of this analysis, a phylogenetic tree was constructed to display the relationships among the homologous sequences that were identified. The study offered a unique opportunity to gain insight into the micropathogens of H. rufipes ticks. The effective control of arthropod vectors in the future will require knowledge of the micropathogen composition of vectors harboring infectious agents. Understanding the ecological factors that regulate vector propagation in association with the prevalence and persistence of micropathogen lineages is also imperative. These interactions may affect the evolution of micropathogen lineages, especially if the micropathogens rely on the vector or host for dispersal. The sRNA deep-sequencing approach used in this analysis provides an intuitive method to survey micropathogen prevalence in ticks and other vector species.