Distinct Compartmentalization of the Chemokines CXCL1 and CXCL2 and the Atypical Receptor ACKR1 Determine Discrete Stages of Neutrophil Diapedesis

Novel neutrophil biology insights underlying atypical chemokine receptor-1/Duffy antigen receptor of chemokines-associated neutropenia

PURPOSE OF REVIEW

Atypical chemokine receptor-1 (ACKR1)/Duffy antigen receptor of chemokines (DARC)-associated neutropenia (ADAN; OMIM 611862), previously named benign ethnic neutropenia, and present in two-thirds of individuals identifying as Black in the USA, is associated with mild to moderate decreases in peripheral neutrophil counts that nevertheless do not lead to increased infections. Consequently, recent initiatives have sought to establish normal neutrophil count reference ranges for ADAN, considering it a normal variant rather than a clinical disorder requiring medical intervention.

RECENT FINDINGS

A limited number of studies elucidating the mechanism of neutropenia in ADAN has suggested that neutrophils may redistribute from peripheral blood to the tissues including the spleen: this might explain why ADAN is not associated with increased risks of infection since the total number of neutrophils in the body remains normal. In this review, we critically examine the research underlying the molecular basis of ADAN.

SUMMARY

Insights into the biology of neutrophils and their trafficking may inform the clinical interpretation of neutropenia in ADAN. The bulk of research suggests that ADAN does not lead to a diminished host defense as do other forms of neutropenia. However, ADAN may lead to increased proinflammatory signaling, with possible implications for senescence of the immune system and predisposition to autoimmunity and cancer.

Atypical chemokine receptors in the immune system

Leukocyte migration is a fundamental component of innate and adaptive immune responses as it governs the recruitment and localization of these motile cells, which is crucial for immune cell priming, effector functions, memory responses and immune regulation. This complex cellular trafficking system is controlled to a large extent via highly regulated production of secreted chemokines and the restricted expression of their membrane-tethered G-protein-coupled receptors. The activity of chemokines and their receptors is also regulated by a subfamily of molecules known as atypical chemokine receptors (ACKRs), which are chemokine receptor-like molecules that do not couple to the classical signalling pathways that promote cell migration in response to chemokine ligation. There has been a great deal of progress in understanding the biology of these receptors and their functions in the immune system in the past decade. Here, we describe the contribution of the various ACKRs to innate and adaptive immune responses, focussing specifically on recent progress. This includes recent findings that have defined the role for ACKRs in sculpting extracellular chemokine gradients, findings that broaden the spectrum of chemokine ligands recognized by these receptors, candidate new additions to ACKR family, and our increasing understanding of the role of these receptors in shaping the migration of innate and adaptive immune cells.

Machine Learning-Driven discovery of immunogenic cell Death-Related biomarkers and molecular classification for diabetic ulcers

In this study, we redefine the diagnostic landscape of diabetic ulcers (DUs), a major diabetes complication. Our research uncovers new biomarkers linked to immunogenic cell death (ICD) in DUs by utilizing RNA-sequencing data of Gene Expression Omnibus (GEO) analysis combined with a comprehensive database interrogation. Employing a random forest algorithm, we have developed a diagnostic model that demonstrates improved accuracy in distinguishing DUs from normal tissue, with satisfactory results from ROC analysis. Beyond mere diagnosis, our model categorizes DUs into novel molecular classifications, which may enhance our comprehension of their underlying pathophysiology. This study bridges the gap between molecular insights and clinical practice. It sets the stage for transformative strategies in DUs management, marking a significant step forward in personalized medicine for diabetic patients.

Single-cell atlas of healthy vocal folds and cellular function in the endothelial-to-mesenchymal transition

The vocal fold is an architecturally complex organ comprising a heterogeneous mixture of various layers of individual epithelial and mesenchymal cell lineages. Here we performed single-cell RNA sequencing profiling of 5836 cells from the vocal folds of adult Sprague-Dawley rats. Combined with immunostaining, we generated a spatial and transcriptional map of the vocal fold cells and characterized the subpopulations of epithelial cells, mesenchymal cells, endothelial cells, and immune cells. We also identified a novel epithelial-to-mesenchymal transition-associated epithelial cell subset that was mainly found in the basal epithelial layers. We further confirmed that this subset acts as intermediate cells with similar genetic features to epithelial-to-mesenchymal transition in head and neck squamous cell carcinoma. Finally, we present the complex intracellular communication network involved homeostasis using CellChat analysis. These studies define the cellular and molecular framework of the biology and pathology of the VF mucosa and reveal the functional importance of developmental pathways in pathological states in cancer.

Association of peripheral inflammatory indicators with osteoarthritis risk

Objectives

Numerous studies have established the role of inflammation in osteoarthritis (OA) progression, yet limited research explores the association between systemic inflammatory indicators and pre-diagnosis OA risk. This study aimed to investigate the association between peripheral inflammatory indicators and the risk of OA using data from the UK Biobank.

Methods

The study analyzed data from 417,507 participants in the UK Biobank, including neutrophil count, lymphocyte count, monocyte count, platelet count, and C-reactive protein meter. Additionally, derived ratios such as NLR(neutrophils-lymphocytes ratio), PLR(Platelets-lymphocytes ratio), SII(systemic immune-inflammation index), and LMR (lymphocytes-monocytes ratio) were examined. Cox proportional hazards models and restricted cubic spline models were used to assess both linear and nonlinear associations.

Results

Over a mean follow-up period of 12.7 years, a total of 49,509 OA events were identified. The findings revealed that CRP (HR:1.06, 95%CI:1.05-1.07), NLR (HR:1.02, 95%CI:1.01-1.03), PLR (HR:1.02, 95%CI:1.01-1.03), and SII (HR:1.03, 95%CI:1.01-1.04) were associated with an increased risk of OA, while LMR (HR:0.97, 95%CI:0.96-0.99) showed a significant negative correlation with OA risk. Subgroup analyses further emphasized that these associations were significant across most of the population. Although neutrophils, lymphocytes, monocytes, and platelets showed a nominal association with the risk of OA, the results were unreliable, especially for specific joint OA.

Conclusion

The study provides evidence of a significant association between elevated peripheral inflammatory indicators and OA risk. These findings underscore the importance of low-grade chronic inflammation in OA development. The potential clinical utility of these indicators as early predictors of OA is suggested, warranting further exploration.

Senescent endothelial cells promote pathogenic neutrophil trafficking in inflamed tissues

Cellular senescence is a hallmark of advanced age and a major instigator of numerous inflammatory pathologies. While endothelial cell (EC) senescence is aligned with defective vascular functionality, its impact on fundamental inflammatory responses in vivo at single-cell level remain unclear. To directly investigate the role of EC senescence on dynamics of neutrophil-venular wall interactions, we applied high resolution confocal intravital microscopy to inflamed tissues of an EC-specific progeroid mouse model, characterized by profound indicators of EC senescence. Progerin-expressing ECs supported prolonged neutrophil adhesion and crawling in a cell autonomous manner that additionally mediated neutrophil-dependent microvascular leakage. Transcriptomic and immunofluorescence analysis of inflamed tissues identified elevated levels of EC CXCL1 on progerin-expressing ECs and functional blockade of CXCL1 suppressed the dysregulated neutrophil responses elicited by senescent ECs. Similarly, cultured progerin-expressing human ECs exhibited a senescent phenotype, were pro-inflammatory and prompted increased neutrophil attachment and activation. Collectively, our findings support the concept that senescent ECs drive excessive inflammation and provide new insights into the mode, dynamics, and mechanisms of this response at single-cell level.

Molecular mechanism of distinct chemokine engagement and functional divergence of the human Duffy antigen receptor

The Duffy antigen receptor is a seven-transmembrane (7TM) protein expressed primarily at the surface of red blood cells and displays strikingly promiscuous binding to multiple inflammatory and homeostatic chemokines. It serves as the basis of the Duffy blood group system in humans and also acts as the primary attachment site for malarial parasite Plasmodium vivax and pore-forming toxins secreted by Staphylococcus aureus. Here, we comprehensively profile transducer coupling of this receptor, discover potential non-canonical signaling pathways, and determine the cryoelectron microscopy (cryo-EM) structure in complex with the chemokine CCL7. The structure reveals a distinct binding mode of chemokines, as reflected by relatively superficial binding and a partially formed orthosteric binding pocket. We also observe a dramatic shortening of TM5 and 6 on the intracellular side, which precludes the formation of the docking site for canonical signal transducers, thereby providing a possible explanation for the distinct pharmacological and functional phenotype of this receptor.

Alveolar epithelial cells mitigate neutrophilic inflammation in lung injury through regulating mitochondrial fatty acid oxidation

Type 2 alveolar epithelial (AT2) cells of the lung are fundamental in regulating alveolar inflammation in response to injury. Impaired mitochondrial long-chain fatty acid β-oxidation (mtLCFAO) in AT2 cells is assumed to aggravate alveolar inflammation in acute lung injury (ALI), yet the importance of mtLCFAO to AT2 cell function needs to be defined. Here we show that expression of carnitine palmitoyltransferase 1a (CPT1a), a mtLCFAO rate limiting enzyme, in AT2 cells is significantly decreased in acute respiratory distress syndrome (ARDS). In mice, Cpt1a deletion in AT2 cells impairs mtLCFAO without reducing ATP production and alters surfactant phospholipid abundance in the alveoli. Impairing mtLCFAO in AT2 cells via deleting either Cpt1a or Acadl (acyl-CoA dehydrogenase long chain) restricts alveolar inflammation in ALI by hindering the production of the neutrophilic chemokine CXCL2 from AT2 cells. This study thus highlights mtLCFAO as immunometabolism to injury in AT2 cells and suggests impaired mtLCFAO in AT2 cells as an anti-inflammatory response in ARDS.

Single-Cell RNA Sequencing Reveals a Unique Fibroblastic Subset and Immune Disorder in Lichen Sclerosus Urethral Stricture

Purpose

Lichen sclerosus urethral stricture disease (LS USD) is a refractory and progressive disease primarily affecting the anterior urethra in males. Various potential etiological factors, such as genetics, autoimmunity, infection, and exposure to infectious urine, have been suggested. However, the accurate etiology of LS in the male urethra remains unclear.

Patients and Methods

In this study, we conducted single-cell RNA sequencing to identify the transcriptional profiles of three patients with LS USD and three patients with non-LS USD. Immunofluorescence was used to confirm the single-cell sequence results.

Results

Our study revealed distinct subsets of vein endothelial cells (ECs), smooth muscle cells (SMCs), and fibroblasts (FBs) with high proportions in LS USD, contributing to the tissue microenvironment primarily involved in proinflammatory and immune responses. In particular, FBs displayed a unique subset, Fib7, which is exclusively present in LS USD, and exhibited high expression levels of SAA1 and SAA2. The accumulation of macrophages, along with the dysregulated ratios of M1/M2-like phenotype macrophages, may be engaged in the pathogenesis of LS USD. Through cell-cell communication analysis, we identified significant interactions involving CXCL8/ACKR1 and CCR7/CCL19 in LS USD. Remarkably, Fib7 exhibited exclusive communication with IL-1B macrophages through the SAA1/FPR2 receptor-ligand pair.

Conclusion

Our study provides a profound understanding of the tissue microenvironment in LS USD, which may be valuable for understanding the pathogenesis of LS USD.

Endothelial Cell-Derived Extracellular Vesicles Promote Aberrant Neutrophil Trafficking and Subsequent Remote Lung Injury

The development of acute respiratory distress syndrome (ARDS) in sepsis is associated with substantial morbidity and mortality. However, the molecular pathogenesis underlying sepsis-induced ARDS remains elusive. Neutrophil heterogeneity and dysfunction contribute to uncontrolled inflammation in patients with ARDS. A specific subset of neutrophils undergoing reverse transendothelial migration (rTEM), which is characterized by an activated phenotype, is implicated in the systemic dissemination of inflammation. Using single-cell RNA sequencing (scRNA-seq), it identified functionally activated neutrophils exhibiting the rTEM phenotype in the lung of a sepsis mouse model using cecal ligation and puncture. The prevalence of neutrophils with the rTEM phenotype is elevated in the blood of patients with sepsis-associated ARDS and is positively correlated with disease severity. Mechanically, scRNA-seq and proteomic analys revealed that inflamed endothelial cell (EC) released extracellular vesicles (EVs) enriched in karyopherin subunit beta-1 (KPNB1), promoting abluminal-to-luminal neutrophil rTEM. Additionally, EC-derived EVs are elevated and positively correlated with the proportion of rTEM neutrophils in clinical sepsis. Collectively, EC-derived EV is identified as a critical regulator of neutrophil rTEM, providing insights into the contribution of rTEM neutrophils to sepsis-associated lung injury.

Identification and Validation of CXCL2 as a Key Gene for Childhood Obesity

This study aims to identify the key genes and their regulatory networks by bioinformatics, increasing understanding of childhood obesity. The data comes from the GEO and Immport database. The immune microenvironment was explored in GSE104815. Key genes were identified by intersection of DEGs with the immune gene set. Enrichment analysis revealed gene-related functions and correlation analysis explored the relationship. Regulatory networks were constructed based on miRcode, TarBase and TargetScan databases. GSE29718 was used to validate our findings. Intercellular communication and cell differentiation trends were further explored using single-cell data from GSE153643. Based on our research, the immune microenvironment in the obese group showed higher immune infiltration. We found 962 DEGs and CXCL2 was identified as the key gene. The co-regulatory network of lncRNA-miRNA-mRNA suggested that obtaining TM4SF19-AS1, GUSBP11, AC105020.1, LINC00189, COL4A2-AS2, VIPR1-AS1 and LINC00242 may regulate CXCL2 (r > 0.9 and P < 0.01). Differential expression of CXCL2 was validated in GSE29718 (P < 0.05) and CXCL2 was identified as a biomarker for childhood obesity (AUC = 0.885). GSVA enrichment analysis revealed many pathways of high group obtaining the TNF-α signaling via NF-κB pathway and interferon γ response pathway. In GSE153643, 11 cell types were identified and CXCL2 was highly expressed in monocyte, macrophage, endothelial cell and pericyte. In CXCL2 high expressing macrophages, there was a tendency for cells to polarize toward M1 macrophages (P < 0.05). In summary, we identified CXCL2 as a potential biomarker of childhood obesity. The development of childhood obesity may be associated with the activation of immune infiltration of macrophage M1 polarization by CXCL2 expression.

Concanavalin-A-Induced Acute Liver Injury in Mice

Acute liver injury is a life-threatening disease. Although immune responses are involved in the development and exacerbation of acute liver injury, the cellular and molecular mechanisms are not fully understood. Intravenous administration of the plant lectin concanavalin A (ConA) is widely used as a model of acute liver injury. ConA triggers T cell activation and cytokine production by crosslinking glycoproteins, including the T cell receptor, leading to the infiltration of myeloid cells into the liver and the subsequent amplification of inflammation in the liver. Thus, the pathogenesis of ConA-induced acute liver injury is considered a model of immune-mediated acute liver injury or autoimmune hepatitis in humans. However, the severity of the liver injury and the analyses of immune cells and non-hematopoietic cells in the liver following ConA injection are significantly influenced by the experimental conditions. This article outlines protocols for ConA-induced acute liver injury in mice and evaluation methods for liver injury, immune cells, and non-hematopoietic cells in the liver. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Induction of acute liver injury by ConA injection Basic Protocol 2: Evaluation of inflammatory cytokines in mouse plasma Basic Protocol 3: Preparation of liver sections and histological analysis of liver injury Basic Protocol 4: Preparation of liver immune cells Basic Protocol 5: Preparation of hepatocytes, endothelial cells, and hepatic stellate cells Basic Protocol 6: Flow cytometry of immune and non-hematopoietic liver cells Basic Protocol 7: Flow cytometric sorting of endothelial cells and hepatic stellate cells Basic Protocol 8: Quantitative reverse transcription polymerase chain reaction.

Spatially targeted chemokine exocytosis guides transmigration at lymphatic endothelial multicellular junctions

Migrating cells preferentially breach and integrate epithelial and endothelial monolayers at multicellular vertices. These sites are amenable to forces produced by the migrating cell and subsequent opening of the junctions. However, the cues that guide migrating cells to these entry portals, and eventually drive the transmigration process, are poorly understood. Here, we show that lymphatic endothelium multicellular junctions are the preferred sites of dendritic cell transmigration in both primary cell co-cultures and in mouse dermal explants. Dendritic cell guidance to multicellular junctions was dependent on the dendritic cell receptor CCR7, whose ligand, lymphatic endothelial chemokine CCL21, was exocytosed at multicellular junctions. Characterization of lymphatic endothelial secretory routes indicated Golgi-derived RAB6+ vesicles and RAB3+/27+ dense core secretory granules as intracellular CCL21 storage vesicles. Of these, RAB6+ vesicles trafficked CCL21 to the multicellular junctions, which were enriched with RAB6 docking factor ELKS (ERC1). Importantly, inhibition of RAB6 vesicle exocytosis attenuated dendritic cell transmigration. These data exemplify how spatially-restricted exocytosis of guidance cues helps to determine where dendritic cells transmigrate.

Distal Immunization and Systemic Cytokines Establish a Transient Immune Alert State in the Intestine

Conventionally, immune responses are studied in the context of inflamed tissues and their corresponding draining lymph nodes (LNs). However, little is known about the effects of systemic inflammatory signals generated during local inflammation on distal tissues and nondraining LNs. Using a mouse model of cutaneous immunization, we found that systemic inflammatory stimuli triggered a rapid and selective distal response in the small intestine and the mesenteric LN (mesLN). This consisted of increased permeability of intestinal blood vessels and lymphatic drainage of bloodborne solutes into the mesLN, enhanced activation and migration of intestinal dendritic cells, as well as amplified T cell responses in the mesLNs to systemic but not orally derived Ags. Mechanistically, we found that the small intestine endothelial cells preferentially expressed molecules involved in TNF-α signaling and that TNF-α blockade markedly diminished distal intestinal responses to cutaneous immunization. Together, these findings reveal that the intestinal immune system is rapidly and selectively activated in response to inflammatory cues regardless of their origin, thus identifying an additional layer of defense and enhanced surveillance of a key barrier organ at constant risk of pathogen encounter.

Functional foods lipids: unraveling their role in the immune response in obesity

Functional lipids are lipids that are found in food matrices and play an important role in influencing human health as their role goes beyond energy storage and structural components. Ongoing research into functional lipids has highlighted their potential to modulate immune responses and other mechanisms associated with obesity, along with its comorbidities. These lipids represent a new field that may offer new therapeutic and preventive strategies for these diseases by understanding their contribution to health. In this review, we discussed in-depth the potential food sources of functional lipids and their reported potential benefit of the major lipid classification: based on their composition such as simple, compound, and derived lipids, and based on their function such as storage and structural, by investigating the intricate mechanisms through which these lipids interact in the human body. We summarize the key insights into the bioaccessibility and bioavailability of the most studied functional lipids. Furthermore, we review the main immunomodulatory mechanisms reported in the literature in the past years. Finally, we discuss the perspectives and challenges faced in the food industry related to functional lipids.

A narrative review of chemokine receptors CXCR1 and CXCR2 and their role in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a severe form of acute respiratory failure characterised by extensive inflammatory injury to the alveolocapillary barrier leading to alveolar oedema, impaired gas exchange and, ultimately, hypoxaemia necessitating the use of supplemental oxygen combined with some degree of positive airway pressure. Although much heterogeneity exists regarding the aetiology, localisation and endotypic characterisation of ARDS, what remains largely undisputed is the role of the innate immune system, and in particular of neutrophils, in precipitating and propagating lung injury. Activated neutrophils, recruited to the lung through chemokine gradients, promote injury by releasing oxidants, proteases and neutrophil extracellular traps, which ultimately cause platelet aggregation, microvascular thrombosis and cellular death. Among various neutrophilic chemoattractants, interleukin-8/C-X-C motif ligand 8 and related chemokines, collectively called ELR+ chemokines, acting on neutrophils through the G protein-coupled receptors CXCR1 and CXCR2, are pivotal in orchestrating the neutrophil activation status and chemotaxis in the inflamed lung. This allows efficient elimination of infectious agents while at the same time minimising collateral damage to host tissue. Therefore, understanding how CXCR1 and CXCR2 receptors are regulated is important if we hope to effectively target them for therapeutic use in ARDS. In the following narrative review, we provide an overview of the role of ELR+ chemokines in acute lung injury (ALI) and ARDS, we summarise the relevant regulatory pathways of their cognisant receptors CXCR1/2 and highlight current preclinical and clinical evidence on the therapeutic role of CXCR1 and CXCR2 inhibition in animal models of ALI, as well as in ARDS patients.

Glycogen synthase kinase 3 activity enhances liver inflammation in MASH

Background & Aims

Metabolic dysfunction-associated steatohepatitis (MASH) is characterized by excessive circulating toxic lipids, hepatic steatosis, and liver inflammation. Monocyte adhesion to liver sinusoidal endothelial cells (LSECs) and transendothelial migration (TEM) are crucial in the inflammatory process. Under lipotoxic stress, LSECs develop a proinflammatory phenotype known as endotheliopathy. However, mediators of endotheliopathy remain unclear.

Methods

Primary mouse LSECs isolated from C57BL/6J mice fed chow or MASH-inducing diets rich in fat, fructose, and cholesterol (FFC) were subjected to multi-omics profiling. Mice with established MASH resulting from a choline-deficient high-fat diet (CDHFD) or FFC diet were also treated with two structurally distinct GSK3 inhibitors (LY2090314 and elraglusib [9-ING-41]).

Results

Integrated pathway analysis of the mouse LSEC proteome and transcriptome indicated that leukocyte TEM and focal adhesion were the major pathways altered in MASH. Kinome profiling of the LSEC phosphoproteome identified glycogen synthase kinase (GSK)-3β as the major kinase hub in MASH. GSK3β-activating phosphorylation was increased in primary human LSECs treated with the toxic lipid palmitate and in human MASH. Palmitate upregulated the expression of C-X-C motif chemokine ligand 2, intracellular adhesion molecule 1, and phosphorylated focal adhesion kinase, via a GSK3-dependent mechanism. Congruently, the adhesive and transendothelial migratory capacities of primary human neutrophils and THP-1 monocytes through the LSEC monolayer under lipotoxic stress were reduced by GSK3 inhibition. Treatment with the GSK3 inhibitors LY2090314 and elraglusib ameliorated liver inflammation, injury, and fibrosis in FFC- and CDHFD-fed mice, respectively. Immunophenotyping using cytometry by mass cytometry by time of flight of intrahepatic leukocytes from CDHFD-fed mice treated with elraglusib showed reduced infiltration of proinflammatory monocyte-derived macrophages and monocyte-derived dendritic cells.

Conclusion

GSK3 inhibition attenuates lipotoxicity-induced LSEC endotheliopathy and could serve as a potential therapeutic strategy for treating human MASH.

Impact and Implications

LSECs under lipotoxic stress in MASH develop a proinflammatory phenotype known as endotheliopathy, with obscure mediators and functional outcomes. The current study identified GSK3 as the major driver of LSEC endotheliopathy, examined its pathogenic role in myeloid cell-associated liver inflammation, and defined the therapeutic efficacy of pharmacological GSK3 inhibitors in murine MASH. This study provides preclinical data for the future investigation of GSK3 pharmacological inhibitors in human MASH. The results of this study are important to hepatologists, vascular biologists, and investigators studying the mechanisms of inflammatory liver disease and MASH, as well as those interested in drug development.

Identification of novel biomarkers related to neutrophilic inflammation in COPD

Background

Chronic obstructive pulmonary disease (COPD) is one of the most prevalent chronic respiratory diseases and the fourth cause of mortality globally. Neutrophilic inflammation has a vital role in the occurrence and progression of COPD. This study aimed to identify the novel hub genes involved in neutrophilic inflammation in COPD through bioinformatic prediction and experimental validation.

Methods

Both the single-cell RNA sequencing (scRNA-seq) dataset (GSE173896) and the RNA sequencing (RNA-seq) dataset (GSE57148) were downloaded from the Gene Expression Omnibus (GEO) database. The Seurat package was used for quality control, dimensions reduction, and cell identification of scRNA-seq. The irGSEA package was used for scoring individual cells. The Monocle2 package was used for the trajectory analysis of neutrophils. The CIBERSORT algorithm was used for analysis of immune cell infiltration in the lungs of COPD patients and controls in RNA-seq dataset, and weighted gene co-expression network analysis (WGCNA) correlated gene modules with neutrophil infiltration. The Mendelian randomization (MR) analysis explored the causal relationship between feature DEGs and COPD. The protein-protein interaction (PPI) network of novel hub genes was constructed, and real-time quantitative polymerase chain reaction (qRT-PCR) was used to validate novel hub genes in clinical specimens.

Results

In scRNA-seq, the gene sets upregulated in COPD samples were related to the neutrophilic inflammatory response and TNF-α activation of the NF-κB signaling pathway. In RNA-seq, immune infiltration analysis showed neutrophils were upregulated in COPD lung tissue. We combined data from differential and modular genes and identified 51 differential genes associated with neutrophilic inflammation. Using MR analysis, 6 genes were explored to be causally associated with COPD. Meanwhile, 11 hub genes were identified by PPI network analysis, and all of them were upregulated. qRT-PCR experiments validated 9 out of 11 genes in peripheral blood leukocytes of COPD patients. Furthermore, 5 genes negatively correlated with lung function in COPD patients. Finally, a network of transcription factors for NAMPT and PTGS2 was constructed.

Conclusion

This study identified nine novel hub genes related to the neutrophilic inflammation in COPD, and two genes were risk factors of COPD, which may serve as potential biomarkers for the clinical severity of COPD.

Decoding the complexity of delayed wound healing following Enterococcus faecalis infection

Wound infections are highly prevalent and can lead to delayed or failed healing, causing significant morbidity and adverse economic impacts. These infections occur in various contexts, including diabetic foot ulcers, burns, and surgical sites. Enterococcus faecalis is often found in persistent non-healing wounds, but its contribution to chronic wounds remains understudied. To address this, we employed single-cell RNA sequencing (scRNA-seq) on infected wounds in comparison to uninfected wounds in a mouse model. Examining over 23,000 cells, we created a comprehensive single-cell atlas that captures the cellular and transcriptomic landscape of these wounds. Our analysis revealed unique transcriptional and metabolic alterations in infected wounds, elucidating the distinct molecular changes associated with bacterial infection compared to the normal wound healing process. We identified dysregulated keratinocyte and fibroblast transcriptomes in response to infection, jointly contributing to an anti-inflammatory environment. Notably, E. faecalis infection prompted a premature, incomplete epithelial-mesenchymal transition in keratinocytes. Additionally, E. faecalis infection modulated M2-like macrophage polarization by inhibiting pro-inflammatory resolution in vitro, in vivo, and in our scRNA-seq atlas. Furthermore, we discovered macrophage crosstalk with neutrophils, which regulates chemokine signaling pathways, while promoting anti-inflammatory interactions with endothelial cells. Overall, our findings offer new insights into the immunosuppressive role of E. faecalis in wound infections.

Multi-omics analysis of human tendon adhesion reveals that ACKR1-regulated macrophage migration is involved in regeneration

Tendon adhesion is a common complication after tendon injury with the development of accumulated fibrotic tissues without effective anti-fibrotic therapies, resulting in severe disability. Macrophages are widely recognized as a fibrotic trigger during peritendinous adhesion formation. However, different clusters of macrophages have various functions and receive multiple regulation, which are both still unknown. In our current study, multi-omics analysis including single-cell RNA sequencing and proteomics was performed on both human and mouse tendon adhesion tissue at different stages after tendon injury. The transcriptomes of over 74 000 human single cells were profiled. As results, we found that SPP1+ macrophages, RGCC+ endothelial cells, ACKR1+ endothelial cells and ADAM12+ fibroblasts participated in tendon adhesion formation. Interestingly, despite specific fibrotic clusters in tendon adhesion, FOLR2+ macrophages were identified as an antifibrotic cluster by in vitro experiments using human cells. Furthermore, ACKR1 was verified to regulate FOLR2+ macrophages migration at the injured peritendinous site by transplantation of bone marrow from Lysm-Cre;R26RtdTomato mice to lethally irradiated Ackr1-/- mice (Ackr1-/- chimeras; deficient in ACKR1) and control mice (WT chimeras). Compared with WT chimeras, the decline of FOLR2+ macrophages was also observed, indicating that ACKR1 was specifically involved in FOLR2+ macrophages migration. Taken together, our study not only characterized the fibrosis microenvironment landscape of tendon adhesion by multi-omics analysis, but also uncovered a novel antifibrotic cluster of macrophages and their origin. These results provide potential therapeutic targets against human tendon adhesion.

Hyperglycaemia perturbs blood-brain barrier integrity through its effects on endothelial cell characteristics and function

Breakdown of blood-brain barrier (BBB) represents a key pathology in hyperglycemia-mediated cerebrovascular damage after an ischemic stroke. As changes in the level and nature of vasoactive agents released by endothelial cells (ECs) may contribute to BBB dysfunction, this study first explored the specific impact of hyperglycemia on EC characteristics and secretome. It then assessed whether secretome obtained from ECs subjected to normoglycaemia or hyperglycemia might regulate pericytic cytokine profile differently. Using a triple cell culture model of human BBB, composed of brain microvascular EC (BMEC), astrocytes and pericytes, this study showed that exposure to hyperglycemia (25 mM D-glucose) for 72 h impaired the BBB integrity and function as evidenced by decreases in transendothelial electrical resistance and increases in paracellular flux of sodium fluorescein. Dissolution of zonula occludens-1, a tight junction protein, and appearance of stress fibers appeared to play a key role in this pathology. Despite elevations in angiogenin, endothelin-1, interleukin-8 and basic fibroblast growth factor levels and a decrease in placental growth factor levels in BMEC subjected to hyperglycemia vs normoglycaemia (5.5 mM D-glucose), tubulogenic capacity of BMECs remained similar in both settings. Similarly, pericytes subjected to secretome obtained from hyperglycemic BMEC released higher quantities of macrophage migration inhibitory factor and serpin and lower quantities of monocyte chemoattractant protein-1, intercellular adhesion molecule, interleukin-6 and interleukin-8. Taken together these findings indicate the complexity of the mechanisms leading to BBB disruption in hyperglycemic settings and emphasize the importance of endothelial cell-pericyte axis in the development of novel therapeutic strategies.

Bazi Bushen ameliorates age-related energy metabolism dysregulation by targeting the IL-17/TNF inflammatory pathway associated with SASP

BACKGROUND

Chronic inflammation and metabolic dysfunction are key features of systemic aging, closely associated with the development and progression of age-related metabolic diseases. Bazi Bushen (BZBS), a traditional Chinese medicine used to alleviate frailty, delays biological aging by modulating DNA methylation levels. However, the precise mechanism of its anti-aging effect remains unclear. In this study, we developed the Energy Expenditure Aging Index (EEAI) to estimate biological age. By integrating the EEAI with transcriptome analysis, we aimed to explore the impact of BZBS on age-related metabolic dysregulation and inflammation in naturally aging mice.

METHODS

We conducted indirect calorimetry analysis on five groups of mice with different ages and utilized the data to construct EEAI. 12 -month-old C57BL/6 J mice were treated with BZBS or β-Nicotinamide Mononucleotide (NMN) for 8 months. Micro-CT, Oil Red O staining, indirect calorimetry, RNA sequencing, bioinformatics analysis, and qRT-PCR were performed to investigate the regulatory effects of BZBS on energy metabolism, glycolipid metabolism, and inflammaging.

RESULTS

The results revealed that BZBS treatment effectively reversed the age-related decline in energy expenditure and enhanced overall metabolism, as indicated by the aging index of energy expenditure derived from energy metabolism parameters across various ages. Subsequent investigations showed that BZBS reduced age-induced visceral fat accumulation and hepatic lipid droplet aggregation. Transcriptomic analysis of perirenal fat and liver indicated that BZBS effectively enhanced lipid metabolism pathways, such as the PPAR signaling pathway, fatty acid oxidation, and cholesterol metabolism, and improved glycolysis and mitochondrial respiration. Additionally, there was a significant improvement in inhibiting the inflammation-related arachidonic acid-linoleic acid metabolism pathway and restraining the IL-17 and TNF inflammatory pathways activated via senescence associated secretory phenotype (SASP).

CONCLUSIONS

BZBS has the potential to alleviate inflammation in metabolic organs of naturally aged mice and maintain metabolic homeostasis. This study presents novel clinical therapeutic approaches for the prevention and treatment of age-related metabolic diseases.

Harnessing anti-inflammatory pathways and macrophage nano delivery to treat inflammatory and fibrotic disorders

Targeting specific organs and cell types using nanotechnology and sophisticated delivery methods has been at the forefront of applicative biomedical sciences lately. Macrophages are an appealing target for immunomodulation by nanodelivery as they are heavily involved in various aspects of many diseases and are highly plastic in their nature. Their continuum of functional "polarization" states has been a research focus for many years yielding a profound understanding of various aspects of these cells. The ability of monocyte-derived macrophages to metamorphose from pro-inflammatory to reparative and consequently to pro-resolving effectors has raised significant interest in its therapeutic potential. Here, we briefly survey macrophages' ontogeny and various polarization phenotypes, highlighting their function in the inflammation-resolution shift. We review their inducing mediators, signaling pathways, and biological programs with emphasis on the nucleic acid sensing-IFN-I axis. We also portray the polarization spectrum of macrophages and the characteristics of their transition between different subtypes. Finally, we highlighted different current drug delivery methods for targeting macrophages with emphasis on nanotargeting that might lead to breakthroughs in the treatment of wound healing, bone regeneration, autoimmune, and fibrotic diseases.

Bcat2-Mediated Branched-Chain Amino Acid Catabolism Is Linked to the Aggravated Inflammation in Obese with Psoriasis Mice

SCOPE

The global prevalence of obesity has significantly increased, presenting a major health challenge. High-fat diet (HFD)-induced obesity is closely related to the disease severity of psoriasis, but the mechanism is not fully understood.

METHODS AND RESULTS

The study utilizes the HFD-induced obesity model along with an imiquimod (IMQ)-induced psoriasis-like mouse model (HFD-IMQ) to conduct transcriptomics and metabolomic analyses. HFD-induced obese mice exhibits more severe psoriasis-like lesions compared to normal diet (ND)-IMQ mice. The expression of genes of the IL-17 signaling pathway (IL-17A, IL-17F, S100A9, CCL20, CXCL1) is significantly upregulated, leading to an accumulation of T cells and neutrophils in the skin. Moreover, the study finds that there is an inhibition of the branched-chain amino acids (BCAAs) catabolism pathway, and the key gene branched-chain amino transferase 2 (Bcat2) is significantly downregulated, and the levels of leucine, isoleucine, and valine are elevated in the HFD-IMQ mice. Furthermore, the study finds that the peroxisome proliferator-activated receptor gamma (PPAR γ) is inhibited, while STAT3 activity is promoted in HFD-IMQ mice.

CONCLUSION

HFD-induced obesity significantly amplifies IL-17 signaling and exacerbates psoriasis, with a potential role played by Bcat2-mediated BCAAs metabolism. The study suggests that BCAA catabolism and PPAR γ-STAT3 exacerbate inflammation in psoriasis with obesity.

The double roles of T cell-mediated immune response in the progression of MASLD

Metabolic dysfunction-associated steatotic liver disease(MASLD), formerly known as non-alcoholic fatty liver disease(NAFLD), has become a major cause of chronic liver disease and a significant risk factor for hepatocellular carcinoma, which poses a huge burden on global public health and economy. MASLD includes steatotic liver disease, steatohepatitis, and cirrhosis, and the latter two cause great harm to human health and life, even complicated with liver cancer. Immunologic mechanism plays a major role in promoting its development into hepatitis and cirrhosis. Now more and more evidences show that T cells play an important role in the progression of MASLD. In this review, we discuss the double roles of T cells in MASLD from the perspective of T cell response pathways, as well as new evidences regarding the possible application of immunomodulatory therapy in MASH.

Atypical chemokine receptors in cancer

Atypical chemokine receptors (ACKRs) are a group of seven-transmembrane spanning serpentine receptors that are structurally homologous to classical G-protein-coupled receptors and bind cognate chemokines with high affinities but do not signal via G-proteins or mediate cell migration. However, ACKRs efficiently modify the availability and function of chemokines in defined microanatomical environments, can signal via intracellular effectors other than G-proteins, and play complex roles in physiology and disease, including in cancer. In this review, we summarize the findings on the diverse contributions of individual ACKRs to cancer development, progression, and tumor-host interactions. We discuss how changes in ACKR expression within tumor affect cancer growth, tumor vascularization, leukocyte infiltration, and metastasis formation, ultimately resulting in differential disease outcomes. Across many studies, ACKR3 expression was shown to support tumor growth and dissemination, whereas ACKR1, ACKR2, and ACKR4 in tumors were more likely to contribute to tumor suppression. With few notable exceptions, the insights on molecular and cellular mechanisms of ACKRs activities in cancer remain sparse, and the intricacies of their involvement are not fully appreciated. This is particularly true for ACKR1, ACKR2 and ACKR4. A better understanding of how ACKR expression and functions impact cancer should pave the way for their future targeting by new and effective therapies.

Novel subsets of peripheral immune cells associated with promoting stroke recovery in mice

AIMS

Peripheral immune cells infiltrating into the brain trigger neuroinflammation after an ischemic stroke. Partial immune cells reprogram their function for neural repair. Which immune cells promote ischemic brain recovery needs further identification.

METHODS

We performed single-cell transcriptomic profiling of CD45high immune cells isolated from the ischemic hemisphere at subacute (5 days) and chronic (14 days) stages after ischemic stroke.

RESULTS

A subset of phagocytic macrophages was associated with neuron projection regeneration and tissue remodeling. We also identified a unique type of T cells with highly expressed macrophage markers, including C1q, Apoe, Hexb, and Fcer1g, which showed high abilities in tissue remodeling, myelination regulation, wound healing, and anti-neuroinflammation. Moreover, natural killer cells decreased cytotoxicity and increased energy and metabolic function in the chronic stage after ischemic stroke. Two subgroups of neutrophils upregulated CCL signals to recruit peripheral immune cells and released CXCL2 to keep self-recruiting at the chronic stage.

CONCLUSIONS

We identified subsets of peripheral immune cells that may provide potential therapeutic targets for promoting poststroke recovery.

STING-Dependent Signaling in Microglia or Peripheral Immune Cells Orchestrates the Early Inflammatory Response and Influences Brain Injury Outcome

While originally identified as an antiviral pathway, recent work has implicated that cyclic GMP-AMP-synthase-Stimulator of Interferon Genes (cGAS-STING) signaling is playing a critical role in the neuroinflammatory response to traumatic brain injury (TBI). STING activation results in a robust inflammatory response characterized by the production of inflammatory cytokines called interferons, as well as hundreds of interferon stimulated genes (ISGs). Global knock-out (KO) mice inhibiting this pathway display neuroprotection with evidence that this pathway is active days after injury; yet, the early neuroinflammatory events stimulated by STING signaling remain understudied. Furthermore, the source of STING signaling during brain injury is unknown. Using a murine controlled cortical impact (CCI) model of TBI, we investigated the peripheral immune and microglial response to injury utilizing male chimeric and conditional STING KO animals, respectively. We demonstrate that peripheral and microglial STING signaling contribute to negative outcomes in cortical lesion volume, cell death, and functional outcomes postinjury. A reduction in overall peripheral immune cell and neutrophil infiltration at the injury site is STING dependent in these models at 24 h. Transcriptomic analysis at 2 h, when STING is active, reveals that microglia drive an early, distinct transcriptional program to elicit proinflammatory genes including interleukin 1-β (IL-1β), which is lost in conditional knock-out mice. The upregulation of alternative innate immune pathways also occurs after injury in these animals, which supports a complex relationship between brain-resident and peripheral immune cells to coordinate the proinflammatory response and immune cell influx to damaged tissue after injury.

Mast cell activation disrupts interactions between endothelial cells and pericytes during early life allergic asthma

Allergic asthma generally starts during early life and is linked to substantial tissue remodeling and lung dysfunction. Although angiogenesis is a feature of the disrupted airway, the impact of allergic asthma on the pulmonary microcirculation during early life is unknown. Here, using quantitative imaging in precision-cut lung slices (PCLSs), we report that exposure of neonatal mice to house dust mite (HDM) extract disrupts endothelial cell/pericyte interactions in adventitial areas. Central to the blood vessel structure, the loss of pericyte coverage was driven by mast cell (MC) proteases, such as tryptase, that can induce pericyte retraction and loss of the critical adhesion molecule N-cadherin. Furthermore, spatial transcriptomics of pediatric asthmatic endobronchial biopsies suggests intense vascular stress and remodeling linked with increased expression of MC activation pathways in regions enriched in blood vessels. These data provide previously unappreciated insights into the pathophysiology of allergic asthma with potential long-term vascular defects.

Pericytes modulate endothelial inflammatory response during bacterial infection

Pericytes are located around blood vessels, in close contact with endothelial cells. We discovered that pericytes dampen pro-inflammatory endothelial cell responses. Endothelial cells co-cultured with pericytes had markedly reduced expression of adhesion molecules (PECAM-1 and ICAM-1) and proinflammatory cytokines (CCL-2 and IL-6) in response to bacterial stimuli (Brucella ovis, Listeria monocytogenes, or Escherichia coli lipopolysaccharide). Pericyte-depleted mice intraperitoneally inoculated with either B. ovis, a stealthy pathogen that does not trigger detectable inflammation, or Listeria monocytogenes, developed peritonitis. Further, during Citrobacter rodentium infection, pericyte-depleted mice developed severe intestinal inflammation, which was not evident in control mice. The anti-inflammatory effect of pericytes required connexin 43, as either chemical inhibition or silencing of connexin 43 abrogated pericyte-mediated suppression of endothelial inflammatory responses. Our results define a mechanism by which pericytes modulate inflammation during infection, which shifts our understanding of pericyte biology: from a structural cell to a pro-active player in modulating inflammation.

IMPORTANCE

A previously unknown mechanism by which pericytes modulate inflammation was discovered. The absence of pericytes or blocking interaction between pericytes and endothelium through connexin 43 results in stronger inflammation, which shifts our understanding of pericyte biology, from a structural cell to a player in controlling inflammation.

Regulation of cancer stem cells by CXCL1, a chemokine whose secretion is controlled by MCM2

BACKGROUND

A high expression pattern of minichromosome maintenance 2 (MCM2) has been observed in various cancers. MCM2 is a protein involved in the cell cycle and plays a role in cancer growth and differentiation by binding to six members of the MCM subfamily. The MCM protein family includes MCM2 through MCM7.

METHODS

MCM2 has shown high expression in both lung cancer stem cells (LCSCs) and glioma stem cells (GSCs). We investigated the characteristics of CSCs and the regulation of the epithelial-to-mesenchymal transition (EMT) phenomenon in LCSCs and GSCs by MCM2. Additionally, we explored secreted factors regulated by MCM2.

RESULTS

There was a significant difference in survival rates between lung cancer patients and brain cancer patients based on MCM2 expression. MCM2 was found to regulate both markers and regulatory proteins in LCSCs. Moreover, MCM2 is thought to be involved in cancer metastasis by regulating cell migration and invasion, not limited to lung cancer but also identified in glioma. Among chemokines, chemokine (C-X-C motif) ligand 1 (CXCL1) was found to be regulated by MCM2.

CONCLUSIONS

MCM2 not only participates in the cell cycle but also affects cancer cell growth by regulating the external microenvironment to create a favorable environment for cells. MCM2 is highly expressed in malignant carcinomas, including CSCs, and contributes to the malignancy of various cancers. Therefore, MCM2 may represent a crucial target for cancer therapeutics.

An Intriguing Structural Modification in Neutrophil Migration Across Blood Vessels to Inflammatory Sites: Progress in the Core Mechanisms

The role and function of neutrophils are well known, but we still have incomplete understanding of the mechanisms by which neutrophils migrate from blood vessels to inflammatory sites. Neutrophil migration is a complex process that involves several distinct steps. To resist the blood flow and maintain their rolling, neutrophils employ tether and sling formation. They also polarize and form pseudopods and uropods, guided by hierarchical chemotactic agents that enable precise directional movement. Meanwhile, chemotactic agents secreted by neutrophils, such as CXCL1, CXCL8, LTB4, and C5a, can recruit more neutrophils and amplify their response. In the context of diapedesis neutrophils traverse the endothelial cells via two pathways: the transmigratory cup and the lateral border recycling department. These structures aid in overcoming the narrow pore size of the endothelial barrier, resulting in more efficient transmembrane migration. Interestingly, neutrophils exhibit a preference for the paracellular pathway over the transcellular pathway, likely due to the former's lower resistance. In this review, we will delve into the intricate process of neutrophil migration by focusing on critical structures that underpins this process.

Implications for neutrophils in cardiac arrhythmias

Cardiac arrhythmias commonly occur as a result of aberrant electrical impulse formation or conduction in the myocardium. Frequently discussed triggers include underlying heart diseases such as myocardial ischemia, electrolyte imbalances, or genetic anomalies of ion channels involved in the tightly regulated cardiac action potential. Recently, the role of innate immune cells in the onset of arrhythmic events has been highlighted in numerous studies, correlating leukocyte expansion in the myocardium to increased arrhythmic burden. Here, we aim to call attention to the role of neutrophils in the pathogenesis of cardiac arrhythmias and their expansion during myocardial ischemia and infectious disease manifestation. In addition, we will elucidate molecular mechanisms associated with neutrophil activation and discuss their involvement as direct mediators of arrhythmogenicity.

Neutrophil hitchhiking nanoparticles enhance bacteria-mediated cancer therapy via NETosis reprogramming

Bacteria have shown great potential in anti-tumor treatment, and an attenuated strain of Salmonella named VNP20009 has been shown to be safe in clinical trials. However, colonized bacteria recruit neutrophils into the tumor, which release NETs to capture and eliminate bacteria, compromising bacterial-based tumor treatment. In this study, we report a neutrophil hitchhiking nanoparticles (SPPS) that block the formation of NET to enhance bacteria-mediated tumor therapy. In the 4 T1 tumor-bearing mouse model, following 24 h of bacterial therapy, there was an approximately 3.0-fold increase in the number of neutrophils in the bloodstream, while the amount of SPPS homing to tumor tissue through neutrophil hitchhiking increased approximately 2.0-fold. It is worth noting that the NETs in tumors significantly decreased by approximately 2.0-fold through an intracellular ROS scavenging-mediated NETosis reprogramming, thereby increasing bacterial vitality by 1.9-fold in tumors. More importantly, the gene drug (siBcl-2) loaded in SPPS can be re-encapsulated in apoptotic bodies by reprogramming neutrophils from NETosis to apoptosis, and enable the redelivery of drugs to tumor cells, further boosting the antitumor efficacy with a synergistic effect, resulting in about 98% tumor inhibition rate and 90% survival rate.

Traditional Chinese Medicine Formulae QY305 Reducing Cutaneous Adverse Reaction and Diarrhea by its Nanostructure

Traditional Chinese medicine (TCM) is widely used in clinical practice, including skin and gastrointestinal diseases. Here, a potential TCM QY305 (T-QY305) is reported that can modulate the recruitment of neutrophil in skin and colon tissue thus reducing cutaneous adverse reaction and diarrhea induced by epidermal growth factor receptor inhibitors (EGFRIs). On another hand, the T-QY305 formula, through regulating neutrophil recruitment features would highlight the presence of N-QY305, a subunit nanostructure contained in T-QY305, and confirm its role as potentially being the biomaterial conferring to T-QY305 its pharmacodynamic features. Here, the clinical records of two patients are analyzed expressing cutaneous adverse reaction and demonstrate positive effect of T-QY305 on the simultaneous inhibition of both cutaneous adverse reaction and diarrhea in animal models. The satisfying results obtained from T-QY305, lead to further process to the isolation of N-QY305 from T-QY305, in order to demonstrate that the potency of T-QY305 originates from the nanostructure N-QY305. Compared to T-QY305, N-QY305 exhibits higher potency upon reducing adverse reactions. The data represent a promising candidate for reducing cutaneous adverse reaction and diarrhea, meanwhile proposing a new strategy to highlight the presence of nanostructures being the "King" of Chinese medicine formula as the pharmacodynamic basis.

Glycosylation of blood cells during the onset and progression of atherosclerosis and myocardial infarction

Protein glycosylation controls cell-cell and cell-extracellular matrix (ECM) communication in immune, vascular, and inflammatory processes, underlining the critical role of this process in the identification of disease biomarkers and the design of novel therapies. Emerging evidence highlights the critical role of blood cell glycosylation in the pathophysiology of atherosclerosis (ATH) and myocardial infarction (MI). Here, we review the role of glycosylation in the interplay between blood cells, particularly erythrocytes, and endothelial cells (ECs), highlighting the involvement of this critical post/cotranslational modification in settings of cardiovascular disease (CVD). Importantly, we focus on emerging preclinical studies and clinical trials based on glycan-targeted drugs to validate their therapeutic potential. These findings may help establish new trends in preventive medicine and delineate novel targeted therapies in CVD.

A metabolic perspective of the neutrophil life cycle: new avenues in immunometabolism

Neutrophils are the most abundant innate immune cells. Multiple mechanisms allow them to engage a wide range of metabolic pathways for biosynthesis and bioenergetics for mediating biological processes such as development in the bone marrow and antimicrobial activity such as ROS production and NET formation, inflammation and tissue repair. We first discuss recent work on neutrophil development and functions and the metabolic processes to regulate granulopoiesis, neutrophil migration and trafficking as well as effector functions. We then discuss metabolic syndromes with impaired neutrophil functions that are influenced by genetic and environmental factors of nutrient availability and usage. Here, we particularly focus on the role of specific macronutrients, such as glucose, fatty acids, and protein, as well as micronutrients such as vitamin B3, in regulating neutrophil biology and how this regulation impacts host health. A special section of this review primarily discusses that the ways nutrient deficiencies could impact neutrophil biology and increase infection susceptibility. We emphasize biochemical approaches to explore neutrophil metabolism in relation to development and functions. Lastly, we discuss opportunities and challenges to neutrophil-centered therapeutic approaches in immune-driven diseases and highlight unanswered questions to guide future discoveries.

How chemokines organize the tumour microenvironment

For our immune system to contain or eliminate malignant solid tumours, both myeloid and lymphoid haematopoietic cells must not only extravasate from the bloodstream into the tumour tissue but also further migrate to various specialized niches of the tumour microenvironment to functionally interact with each other, with non-haematopoietic stromal cells and, ultimately, with cancer cells. These interactions regulate local immune cell survival, proliferative expansion, differentiation and their execution of pro-tumour or antitumour effector functions, which collectively determine the outcome of spontaneous or therapeutically induced antitumour immune responses. None of these interactions occur randomly but are orchestrated and critically depend on migratory guidance cues provided by chemokines, a large family of chemotactic cytokines, and their receptors. Understanding the functional organization of the tumour immune microenvironment inevitably requires knowledge of the multifaceted roles of chemokines in the recruitment and positioning of its cellular constituents. Gaining such knowledge will not only generate new insights into the mechanisms underlying antitumour immunity or immune tolerance but also inform the development of biomarkers (or 'biopatterns') based on spatial tumour tissue analyses, as well as novel strategies to therapeutically engineer immune responses in patients with cancer. Here we will discuss recent observations on the role of chemokines in the tumour microenvironment in the context of our knowledge of their physiological functions in development, homeostasis and antimicrobial responses.

Chemokines in Cartilage Regeneration and Degradation: New Insights

Cartilage plays a crucial role in the human body by forming long bones during development and growth to bear loads on joints and intervertebral discs. However, the increasing prevalence of cartilage degenerative disorders is a growing public health concern, especially due to the poor innate regenerative capacity of cartilage. Chondrocytes are a source of several inflammatory mediators that play vital roles in the pathogenesis of cartilage disorders. Among these mediators, chemokines have been explored as potential contributors to cartilage degeneration and regeneration. Our review focuses on the progress made during the last ten years in identifying the regulators and roles of chemokines and their receptors in different mechanisms related to chondrocytes and cartilage. Recent findings have demonstrated that chemokines influence cartilage both positively and negatively. Their induction and involvement in either process depends on the local molecular environment and is both site- and time-dependent. One of the challenges in defining the role of chemokines in cartilage pathology or regeneration is the apparent redundancy in the interaction of chemokines with their receptors. Hence, it is crucial to determine, for each situation, whether targeting specific chemokines or their receptors will help in developing effective therapeutic strategies for cartilage repair.

Prolonged sleep deprivation induces a cytokine-storm-like syndrome in mammals

Most animals require sleep, and sleep loss induces serious pathophysiological consequences, including death. Previous experimental approaches for investigating sleep impacts in mice have been unable to persistently deprive animals of both rapid eye movement sleep (REMS) and non-rapid eye movement sleep (NREMS). Here, we report a "curling prevention by water" paradigm wherein mice remain awake 96% of the time. After 4 days of exposure, mice exhibit severe inflammation, and approximately 80% die. Sleep deprivation increases levels of prostaglandin D2 (PGD2) in the brain, and we found that elevated PGD2 efflux across the blood-brain-barrier-mediated by ATP-binding cassette subfamily C4 transporter-induces both accumulation of circulating neutrophils and a cytokine-storm-like syndrome. Experimental disruption of the PGD2/DP1 axis dramatically reduced sleep-deprivation-induced inflammation. Thus, our study reveals that sleep-related changes in PGD2 in the central nervous system drive profound pathological consequences in the peripheral immune system.

TGFβ1 induces CXCL1 to promote stemness features in lung cancer

Chemokines critically orchestrate the tumorigenesis, metastasis, and stemness features of cancer cells that lead to poor outcomes. High plasma levels of transforming growth factor-β1 (TGFβ1) correlate with poor prognostic features in advanced lung cancer patients, thus suggesting the importance of TGFβ1 in the lung tumor microenvironment. However, the role of chemokines in TGFβ1-induced tumor stemness features remains unclear. Here, we clarify the previously undocumented role of CXCL1 in TGFβ1-induced lung cancer stemness features. CXCL1 and its receptor CXCR2 were significantly upregulated in TGFβ1-induced lung cancer stem cells (CSCs). CXCL1 silencing (shCXCL1) suppressed stemness gene expression, tumorsphere formation, colony formation, drug resistance, and in vivo tumorigenicity in TGFβ1-induced lung tumorspheres. Immunohistochemistry staining showed that patients with stage II/III lung cancer had higher expression levels of CXCL1. The levels of CXCL1 were positively associated with lymph node metastasis and correlated with the expression of the CSC transcription factor Oct-4. Furthermore, online database analysis revealed that CXCL1 expression was negatively correlated with lung cancer survival in patients. Patients with high TGFβ1/CXCL1/CD44 co-expression had a worse survival rate. We suggest that CXCL1 serves as a crucial factor in TGFβ1-induced stemness features of lung cancer.

C-C chemokine receptor 5 is essential for conventional NK cell trafficking and liver injury in a murine hepatitis virus-induced fulminant hepatic failure model

BACKGROUND

Previous studies have demonstrated that natural killer (NK) cells migrated into the liver from peripheral organs and exerted cytotoxic effects on hepatocytes in virus-induced liver failure.

AIM

This study aimed to investigate the potential therapeutic role of chemokine receptors in the migration of NK cells in a murine hepatitis  virus strain 3 (MHV-3)-induced fulminant hepatic failure (MHV-3-FHF) model and its mechanism.

RESULTS

By gene array analysis, chemokine (C-C motif) receptor 5 (CCR5) was found to have remarkably elevated expression levels in hepatic NK cells after MHV-3 infection. The number of hepatic CCR5+ conventional NK (cNK) cells increased and peaked at 48 h after MHV-3 infection, while the number of hepatic resident NK (rNK) cells steadily declined. Moreover, the expression of CCR5-related chemokines, including macrophage inflammatory protein (MIP)-1α, MIP-1β and regulated on activation, normal T-cell expressed and secreted (RANTES) was significantly upregulated in MHV-3-infected hepatocytes. In an in vitro Transwell migration assay, CCR5-blocked splenic cNK cells showed decreased migration towards MHV-3-infected hepatocytes, and inhibition of MIP-1β or RANTES but not MIP-1α decreased cNK cell migration. Moreover, CCR5 knockout (KO) mice displayed reduced infiltration of hepatic cNK cells after MHV-3 infection, accompanied by attenuated liver injury and improved mouse survival time. Adoptive transfer of cNK cells from wild-type mice into CCR5 KO mice resulted in the abundant accumulation of hepatic cNK cells and aggravated liver injury. Moreover, pharmacological inhibition of CCR5 by maraviroc reduced cNK cell infiltration in the liver and liver injury in the MHV-3-FHF model.

CONCLUSION

The CCR5-MIP-1β/RANTES axis played a critical role in the recruitment of cNK cells to the liver during MHV-3-induced liver injury. Targeted inhibition of CCR5 provides a therapeutic approach to ameliorate liver damage during virus-induced acute liver injury.

Chemokine Cxcl1-Cxcl2 heterodimer is a potent neutrophil chemoattractant

Microbial infection is characterized by release of multiple proinflammatory chemokines that direct neutrophils to the insult site. How collective function of these chemokines orchestrates neutrophil recruitment is not known. Here, we characterized the role for heterodimer and show that the Cxcl1-Cxcl2 heterodimer is a potent neutrophil chemoattractant in mice and can recruit more neutrophils than the individual chemokines. Chemokine-mediated neutrophil recruitment is determined by Cxcr2 receptor signaling, Cxcr2 endocytosis, and binding to glycosaminoglycans. We have now determined heterodimer's Cxcr2 activity using cellular assays and Cxcr2 density in blood and recruited neutrophils in heterodimer-treated mice. We have shown that the heterodimer binds glycosaminoglycans with higher affinity and more efficiently than Cxcl1 or Cxcl2. These data collectively indicate that optimal glycosaminoglycan interactions and dampened receptor activity acting in concert in a dynamic fashion promote heterodimer-mediated robust neutrophil recruitment. We propose that this could play a critical role in combating infection.

The Role of Atypical Chemokine Receptors in Neuroinflammation and Neurodegenerative Disorders

Neuroinflammation is associated with several neurodegenerative disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). Neuroinflammation provides protection in acute situations but results in significant damage to the nervous system if chronic. Overexpression of chemokines within the brain results in the recruitment and activation of glial and peripheral immune cells which can propagate a cascading inflammatory response, resulting in neurodegeneration and the onset of neurodegenerative disorders. Recent work has identified the role of atypical chemokine receptors (ACKRs) in neurodegenerative conditions. ACKRs are seven-transmembrane domain receptors that do not follow canonical G protein signaling, but regulate inflammatory responses by modulating chemokine abundance, location, and availability. This review summarizes what is known about the four ACKRs and three putative ACKRs within the brain, highlighting their known expression and discussing the current understanding of each ACKR in the context of neurodegeneration. The ability of ACKRs to alter levels of chemokines makes them an appealing therapeutic target for neurodegenerative conditions. However, further work is necessary to understand the expression of several ACKRs within the neuroimmune system and the effectiveness of targeted drug therapies in the prevention and treatment of neurodegenerative conditions.

Chemokines form complex signals during inflammation and disease that can be decoded by extracellular matrix proteoglycans

Chemokine-driven leukocyte recruitment is a key component of the immune response and of various diseases. Therapeutically targeting the chemokine system in inflammatory disease has been unsuccessful, which has been attributed to redundancy. We investigated why chemokines instead have specific, specialized functions, as demonstrated by multiple studies. We analyzed the expression of genes encoding chemokines and their receptors across species, tissues, and diseases. This analysis revealed complex expression patterns such that genes encoding multiple chemokines that mediated recruitment of the same leukocyte type were expressed in the same context, such as the genes encoding the CXCR3 ligands CXCL9, CXCL10, and CXCL11. Through biophysical approaches, we showed that these chemokines differentially interacted with extracellular matrix glycosaminoglycans (ECM GAGs), which was enhanced by sulfation of specific GAGs. Last, in vivo approaches demonstrated that GAG binding was critical for the CXCL9-dependent recruitment of specific T cell subsets but not of others, irrespective of CXCR3 expression. Our data demonstrate that interactions with ECM GAGs regulated whether chemokines were presented on cell surfaces or remained more soluble, thereby affecting chemokine availability and ensuring specificity of chemokine action. Our findings provide a mechanistic understanding of chemokine-mediated immune cell recruitment and identify strategies to target specific chemokines during inflammatory disease.

DNAM-1 Immunoreceptor Protects Mice from Concanavalin A-Induced Acute Liver Injury by Reducing Neutrophil Infiltration

DNAX accessory molecule-1 (DNAM-1; CD226) is an activating immunoreceptor on T cells and NK cells. The interaction of DNAM-1 with its ligand CD155 expressed on hematopoietic and nonhematopoietic cells plays an important role in innate and adaptive immune responses. In this study, we investigated the role of the DNAM-1-CD155 axis in the pathogenesis of T cell-mediated Con A-induced acute liver injury. Unexpectedly, DNAM-1-deficient (Cd226-/-) mice exhibited more severe acute liver injury and higher concentrations of IL-6 and TNF-α than did wild-type (WT) mice after Con A injection. We found that a larger number of neutrophils infiltrated into the liver of Cd226-/- mice compared with WT mice after Con A injection. Depletion of neutrophils ameliorated liver injury and decreased IL-6 and TNF-α in Cd226-/- mice after Con A injection, suggesting that neutrophils exacerbate the liver injury in Cd226-/- mice. Hepatocytes produced more significant amounts of CXCL1, a chemoattractant for neutrophils, in Cd226-/- mice than in WT mice after Con A injection. In the coculture of hepatocytes with liver lymphocytes, either DNAM-1 deficiency in liver lymphocytes or CD155 deficiency in hepatocytes promoted CXCL1 production by hepatocytes. These results suggest that the interaction of DNAM-1 with CD155 inhibits CXCL1 production by hepatocytes, leading to ameliorating acute liver injury.

Canonical and atypical chemokine receptors in the neutrophil life cycle

Chemokines are mainly studied for their local function in the control of leukocyte extravasation in homeostatic and inflammatory conditions. However, they have additional roles at the systemic level including the regulation of the hematopoietic process and leukocyte differentiation. Due to the redundancy and pleiotropicity of the chemokine system, chemokines have often multiple and complex roles in neutrophil differentiation ranging from retention and control of proliferation of progenitors to the mobilization of mature cells from the bone marrow (BM) to the bloodstream and their further differentiation in tissues. Atypical chemokine receptors (ACKRs) are regulators of the chemokine system by controlling chemokine bioavailability and chemokine receptor function. Even though ACKRs bind a wide range of chemokines, they appear to have a selective role in the process of neutrophil production and differentiation. The aim of this review is to give an overview of the current evidence regarding the role of chemokines and chemokine receptors in the life of neutrophils with a focus on the regulation exerted by ACKRs.

The Pro-Tumor Biological Function of IL-36α Plays an Important Role in the Tumor Microenvironment of HCC

Purpose

To investigate the role of IL-36 in the tumorigenesis of hepatocellular carcinoma (HCC). IL-36 composed of a natural antagonist (IL-36Ra) and three agonists (IL-36α, -β, -γ) that stimulate inflammation by binding to a common receptor consisting of IL-36R and IL-1RAcP. HCC is a common malignancy associated with high morbidity and mortality, often diagnosed at later stages. Although the exact role of IL-36α in HCC remains controversial, it is hypothesized that it may play a significant role in the development and progression of this cancer.

Materials and Methods

In the current study, we measured both circulating and intrahepatic levels of IL-36α from HCC patients and healthy controls, using ELISA. The association between IL-36 and the differentiation of HCC was determined. Furthermore, the role IL-36 in both HCC and non-HCC cell lines was evaluated in vitro.

Results

Circulating and intra-hepatic IL-36α was inversely correlated with differentiation of HCC, suggesting that IL-36α contribute to protection during the development of HCC. Based on bioinformatics, miR-27b-3p is closely related to downstream IL-36α. Thus, we determined miR-27b-3p expression in HCC tissues, showing upregulated miR-27b-3p was inversely correlated with IL-36α in HCC, perhaps via CXCL1 in HCC cells. It was confirmed that IL-36α inhibited HCC proliferation, viability and migration in vitro, consistent with reduced the expression of cytokines IL-1β, IL-18, implying that IL-36α inhibited the possible involvement of pyroptosis.

Conclusion

Our data suggests that IL-36α may be a potential therapeutic target and a prediction biomarker for the management of HCC.

Bioinformatic Analysis of the CXCR2 Ligands in Cancer Processes

Human CXCR2 has seven ligands, i.e., CXCL1, CXCL2, CXCL3, CXCL5, CXCL6, CXCL7, and CXCL8/IL-8-chemokines with nearly identical properties. However, no available study has compared the contribution of all CXCR2 ligands to cancer progression. That is why, in this study, we conducted a bioinformatic analysis using the GEPIA, UALCAN, and TIMER2.0 databases to investigate the role of CXCR2 ligands in 31 different types of cancer, including glioblastoma, melanoma, and colon, esophageal, gastric, kidney, liver, lung, ovarian, pancreatic, and prostate cancer. We focused on the differences in the regulation of expression (using the Tfsitescan and miRDB databases) and analyzed mutation types in CXCR2 ligand genes in cancers (using the cBioPortal). The data showed that the effect of CXCR2 ligands on prognosis depends on the type of cancer. CXCR2 ligands were associated with EMT, angiogenesis, recruiting neutrophils to the tumor microenvironment, and the count of M1 macrophages. The regulation of the expression of each CXCR2 ligand was different and, thus, each analyzed chemokine may have a different function in cancer processes. Our findings suggest that each type of cancer has a unique pattern of CXCR2 ligand involvement in cancer progression, with each ligand having a unique regulation of expression.

Integrated transcriptomic and metabolomic profiles reveal the protective mechanism of modified Danggui Buxue decoction on radiation-induced leukopenia in mice

Leukopenia caused by radiation hinders the continuous treatment of cancers. Danggui Buxue Decoction (DBD) has been widely used in clinical owing to low toxicity and definite therapeutic effects to increase leukocytes. Meanwhile, icaritin (ICT) has also been proved to have the effect of boosting peripheral blood cells proliferation. However, there is no study to prove the efficacy of MDBD (Modified Danggui Buxue Decoction), a derivative herbal formula composed of DBD and ICT, in the treatment of radiation-induced leukopenia. In this study, we performed a model of 3.5 Gy whole-body radiation to induce leukopenia in mice. The results of pharmacodynamic studies demonstrated that MDBD could significantly increase the white blood cells in peripheral blood by improving the activity of bone marrow nuclear cells, reducing bone marrow damage, modulating spleen index, and regulating hematopoietic factors to alleviate leukopenia. We also analyzed the integrated results of metabolomics and transcriptomics and found that MDBD could relieve leukopenia and alleviate bone marrow damage by targeting steroid biosynthesis and IL-17 signaling pathway, in which the key genes are Jun, Cxcl2 and Egr1. Therefore, our study provides a basis for the effectiveness and compatibility in the combination of traditional Chinese medicine formula and small molecule drugs.