Human Monocyte Subsets and Phenotypes in Major Chronic Inflammatory Diseases

Causal Role of Immune Cells in Chronic Obstructive Pulmonary Disease: A Two-Sample Mendelian Randomization Study

Accumulating evidence has highlighted the importance of immune cells in the pathogenesis of chronic obstructive pulmonary disease (COPD). However, the understanding of the causal association between immunity and COPD remains incomplete due to the existence of confounding variables. In this study, we employed a two-sample Mendelian randomization (MR) analysis, utilizing the genome-wide association study database, to investigate the causal association between 731 immune-cell signatures and the susceptibility to COPD from a host genetics perspective. To validate the consistency of our findings, we utilized MR analysis results of lung function data to assess directional concordance. Furthermore, we employed MR-Egger intercept tests, Cochrane's Q test, MR-PRESSO global test, and "leave-one-out" sensitivity analyses to evaluate the presence of horizontal pleiotropy, heterogeneity, and stability, respectively. Inverse variance weighting results showed that seven immune phenotypes were associated with the risk of COPD. Analyses of heterogeneity and pleiotropy analysis confirmed the reliability of MR results. These results highlight the interactions between the immune system and the lungs. Further investigations into their mechanisms are necessary and will contribute to inform targeted prevention strategies for COPD.

PFDN5 plays a dual role in breast cancer and regulates tumor immune microenvironment: Insights from integrated bioinformatics analysis and experimental validation

BACKGROUND

Although the prognosis for patients with breast cancer has improved, breast cancer remains the leading cause of death for women worldwide. Prefoldin 5 (PFDN5), as a subunit of the prefoldin complex, plays a vital role in aiding the correct folding of newly synthesized proteins. However, the exact impact of PFDN5 on breast cancer development and its prognostic implications remain unclear.

METHODS

We conducted bioinformatics analysis to investigate the correlation between PFDN5 and patient survival, as well as various clinicopathological characteristics in breast cancer. Additionally, various assays were employed to validate the biological functions of PFDN5 in breast cancer. Finally, RNA sequencing (RNA-seq) was utilized to investigate the molecular mechanisms associated with PFDN5.

RESULTS

Compared to normal tissues, PFDN5 exhibited lower expression levels in breast cancer tissues, and lower expression of PFDN5 is associated with poorer prognosis. PFDN5 led to G2/M phase arrest in the cell cycle and reduced proliferative potential in breast cancer cells. However, PFDN5 also promoted migration and invasion of breast cancer cells. Also, RNA-seq analysis revealed an involvement of PFDN5 in the cell cycle and TGF-β signaling pathway. Furthermore, PFDN5 had a significant impact on tumor immune microenvironment by promoting macrophage polarization towards the M1 phenotype and exhibited a positive correlation with CD8+ T cell infiltration levels.

CONCLUSIONS

PFDN5 plays a dual role in breast cancer and serves as a key factor in tumor immune microenvironment. Therefore, PFDN5 holds promise as a valuable biomarker for predicting both metastatic and prognosis in breast cancer.

Evaluating different methods for kidney recellularization

This study explores a potential solution to the shortage of kidneys for transplantation in end-stage renal disease (ESRD). Currently, kidney transplantation stands as the optimal option, yet the scarcity of organs persists. Employing tissue engineering, researchers sought to assess the feasibility of generating kidneys for transplantation. Pig kidneys were utilized since they possess higher similarities to human kidneys. Cells were removed via decellularization, which maintains the organ's microarchitecture. Subsequently, pig kidney cells and human red blood cells were perfused into the vacant kidney structure to reconstitute it. The methodologies employed showed promising results, suggesting a viable approach to increase the recellularization rate in whole pig kidneys. This proof-of-concept establishes a groundwork for potentially extending this technology to human kidneys, tackling the organ shortage, thus positively enhancing outcomes for ESRD patients by increasing the availability of transplantable organs.

Therapeutic implications for the PD-1 axis in cerebrovascular injury

Since the discovery and characterization of the PD-1/PD-L pathway, mounting evidence has emerged regarding its role in regulating neuroinflammation following cerebrovascular injury. Classically, PD-L1 on antigen-presenting cells or tissues binds PD-1 on T cell surfaces resulting in T cell inhibition. In myeloid cells, PD-1 stimulation induces polarization of microglia and macrophages into an anti-inflammatory, restorative phenotype. The therapeutic potential of PD-1 agonism in ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage-related vasospasm, and traumatic brain injury rests on the notion of harnessing the immunomodulatory function of immune checkpoint pathways to temper the harmful effects of immune overactivation and secondary injury while promoting repair and recovery. Immune checkpoint agonism has greater specificity than the wider and non-specific anti-inflammatory effects of other agents, such as steroids. PD-1 agonism has already demonstrated success in clinical trials for rheumatoid arthritis and is being tested in other chronic inflammatory diseases. Further investigation of PD-1 agonism as a therapeutic strategy in cerebrovascular injury can help clarify the mechanisms underlying clinical benefit, develop drugs with optimal pharmacodynamic and pharmacokinetic properties, and mitigate unwanted side effects.

Synergy Between NK Cells and Monocytes in Potentiating Cardiovascular Disease Risk in Severe COVID-19

BACKGROUND

Evidence suggests that COVID-19 predisposes to cardiovascular diseases (CVDs). While monocytes/macrophages play a central role in the immunopathogenesis of atherosclerosis, less is known about their immunopathogenic mechanisms that lead to CVDs during COVID-19. Natural killer (NK) cells, which play an intermediary role during pathologies like atherosclerosis, are dysregulated during COVID-19. Here, we sought to investigate altered immune cells and their associations with CVD risk during severe COVID-19.

METHODS

We measured plasma biomarkers of CVDs and determined phenotypes of circulating immune subsets using spectral flow cytometry. We compared these between patients with severe COVID-19 (severe, n=31), those who recovered from severe COVID-19 (recovered, n=29), and SARS-CoV-2-uninfected controls (controls, n=17). In vivo observations were supported using in vitro assays to highlight possible mechanistic links between dysregulated immune subsets and biomarkers during and after COVID-19. We performed multidimensional analyses of published single-cell transcriptome data of monocytes and NK cells during severe COVID-19 to substantiate in vivo findings.

RESULTS

During severe COVID-19, we observed alterations in cardiometabolic biomarkers including oxidized-low-density lipoprotein, which showed decreased levels in severe and recovered groups. Severe patients exhibited dysregulated monocyte subsets, including increased frequencies of proinflammatory intermediate monocytes (also observed in the recovered) and decreased nonclassical monocytes. All identified NK-cell subsets in the severe COVID-19 group displayed increased expression of activation and tissue-resident markers, such as CD69 (cluster of differentiation 69). We observed significant correlations between altered immune subsets and plasma oxidized-low-density lipoprotein levels. In vitro assays revealed increased uptake of oxidized-low-density lipoprotein into monocyte-derived macrophages in the presence of NK cells activated by plasma of patients with severe COVID-19. Transcriptome analyses confirmed enriched proinflammatory responses and lipid dysregulation associated with epigenetic modifications in monocytes and NK cells during severe COVID-19.

CONCLUSIONS

Our study provides new insights into the involvement of monocytes and NK cells in the increased CVD risk observed during and after COVID-19.

Novel Long Noncoding RNA HEAT4 Affects Monocyte Subtypes, Reducing Inflammation and Promoting Vascular Healing

BACKGROUND

Activation of the immune system contributes to cardiovascular diseases. The role of human-specific long noncoding RNAs in cardioimmunology is poorly understood.

METHODS

Single-cell sequencing in peripheral blood mononuclear cells revealed a novel human-specific long noncoding RNA called HEAT4 (heart failure-associated transcript 4). HEAT4 expression was assessed in several in vitro and ex vivo models of immune cell activation, as well as in the blood of patients with heart failure (HF), acute myocardial infarction, or cardiogenic shock. The transcriptional regulation of HEAT4 was verified through cytokine treatment and single-cell sequencing. Loss-of-function and gain-of-function studies and multiple RNA-protein interaction assays uncovered a mechanistic role of HEAT4 in the monocyte anti-inflammatory gene program. HEAT4 expression and function was characterized in a vascular injury model in NOD.CB17-Prkdc scid/Rj mice.

RESULTS

HEAT4 expression was increased in the blood of patients with HF, acute myocardial infarction, or cardiogenic shock. HEAT4 levels distinguished patients with HF from people without HF and predicted all-cause mortality in a cohort of patients with HF over 7 years of follow-up. Monocytes, particularly anti-inflammatory CD16+ monocytes, which are increased in patients with HF, are the primary source of HEAT4 expression in the blood. HEAT4 is transcriptionally activated by treatment with anti-inflammatory interleukin-10. HEAT4 activates anti-inflammatory and inhibits proinflammatory gene expression. Increased HEAT4 levels result in a shift toward more CD16+ monocytes. HEAT4 binds to S100A9, causing a monocyte subtype switch, thereby reducing inflammation. As a result, HEAT4 improves endothelial barrier integrity during inflammation and promotes vascular healing after injury in mice.

CONCLUSIONS

These results characterize a novel endogenous anti-inflammatory pathway that involves the conversion of monocyte subtypes into anti-inflammatory CD16+ monocytes. The data identify a novel function for the class of long noncoding RNAs by preventing protein secretion and suggest long noncoding RNAs as potential targets for interventions in the field of cardioimmunology.

The intervention of macrophages in progressive fibrosis characterizing systemic sclerosis: A systematic review

BACKGROUND AND AIM

Systemic sclerosis (SSc) is an immune mediated connective tissue disease characterized by microvascular dysfunction, aberrant immune response, and progressive fibrosis. Although the immuno-pathophysiological mechanisms underlying SSc are not fully clarified, they are often associated with a dysfunctional macrophage activation toward an alternative (M2) phenotype induced by cytokines [i.e., IL-4, IL-10, IL-13, and transforming growth factor (TGF-β)] involved in the fibrotic and anti-inflammatory process. A spectrum of macrophage activation state has been identified ranging from M1 to M2 phenotype, gene expression of phenotype markers, and functional aspects. This systematic review aims to analyze the importance of M2 macrophage polatization during the immune mediated process and the identification of specific pathways, cytokines, and chemokines involved in SSc pathogenesis. Moreover, this review provides an overview on the in vitro and in vivo studies aiming to test therapeutic strategies targeting M2 macrophages.

METHODS

A systematic literature review was performed according to the preferred Reported Items for Systematic Reviews and Meta-Analyses (PRISMA). The search encompassed the online medical databases PubMed and Embase up to the 30th of June 2024. Original research manuscripts (in vitro study, in vivo study), animal model and human cohort, were considered for the review. Exclusion criteria encompassed reviews, case reports, correspondences, and conference abstracts/posters. The eligible manuscripts main findings were critically analyzed, discussed, and summarized in the correspondent tables.

RESULTS

Out of the 77 screened abstracts, 49 papers were deemed eligible. Following a critical analysis, they were categorized according to the primary (29 original articles) and secondary (20 original articles) research objectives of this systematic review. The data from the present systematic review suggest the pivotal role of M2 macrophages differentiation and activation together with the dysregulation of the immune system in the SSc pathogenesis. Strong correlations have been found between M2 macrophage presence and clinical manifestations in both murine and human tissue samples. Interestingly, the presence of M2 cell surface markers on peripheral blood monocytes has been highlighted, suggesting a potential biomarker role for this finding. Therapeutic effects reducing M2 macrophage activities have been observed and/or tested for existing and for new drugs, demonstrating potential efficacy in modulating the pro-fibrotic immune response for treatment of SSc.

CONCLUSIONS

The increased M2 macrophage activation in course of SSc seems to offer new insights on the self-amplifying inflammatory and fibrotic response by the immune system on such disease. Therefore, the revaluation of immunomodulatory and ongoing antifibrotic therapies, as well as novel therapeutical approaches in SSc that contribute to limit the M2 macrophage activation are matter of intense investigations.

Inhibition of Mac-1 allows human macrophages to migrate against the direction of shear flow on ICAM-1

All immune cells must transit from the blood to distal sites such as the lymph nodes, bone marrow, or sites of infection. Blood borne monocytes traffic to the site of inflammation by adhering to the endothelial surface and migrating along endothelial intracellular adhesion molecule 1 (ICAM-1) by their ligand's macrophage 1 antigen (Mac-1) and lymphocyte functional antigen 1 (LFA-1) to transmigrate through the endothelium. Poor patient prognoses in chronic inflammation and tumors have been attributed to the hyper recruitment of certain types of macrophages. Therefore, targeting the binding of ICAM-1 to its respective ligands provides a novel approach to targeting the recruitment of macrophages. To that end, we determined whether the loss of Mac-1 expression could induce this upstream migration behavior by using blocking antibodies against Mac-1 to examine the effects of hydrodynamic flow on the migration of the human macrophage cell line U-937 on ICAM-1 surfaces. Blocking Mac-1 on U-937 cells led to upstream migration against the direction of shear flow on ICAM-1 surfaces. In sum, the ability of macrophages to migrate upstream when Mac-1 is blocked represents a new avenue to precisely control the differentiation, migration, and trafficking of macrophages.

Improved levels of checkpoint molecule PD-L1 on peripheral blood monocyte subsets in obstructive sleep apnea syndrome patients upon hypoglossal nerve stimulation

Oxidative stress in patients suffering from obstructive sleep apnea syndrome (OSAS) is associated with a low-grade systemic inflammation, immune disturbance, and increased invasion of monocytes into the endothelium. Besides continuous positive airway pressure (PAP), hypoglossal nerve stimulation (HNS) has become a promising treatment option for patients with OSAS. We aimed to analyse the influence of HNS therapy on the cellular characteristics relevant for adhesion and immune regulation of circulating CD14/CD16 monocyte subsets. Whole blood flow cytometric measurements were performed to analyse the expression levels of different adhesion molecules and checkpoint molecule PD-L1 (programmed death-ligand 1) in connection with pro-inflammatory plasma cytokine IL-8 and the clinical values of BMI (body mass index), AHI (apnea-hypopnea index), ODI (oxygen desaturation index), and ESS (Epworth sleepiness scale) upon HNS treatment. Hypoglossal nerve stimulation treatment significantly improved the expression of adhesion molecule CD162 (P-selectin receptor) on non-classical monocytes and significantly downregulated the expression of PD-L1 on all three monocyte subsets. We conclude that the holistic improvement of different parameters such as the oxygenation of the peripheral blood, a reduced systemic inflammation, and the individual sleeping situation upon HNS respiratory support, leads to an improved immunologic situation.

Effect of Siegesbeckia glabrescens Extract on Foam Cell Formation in THP-1 Macrophages

The accumulation of cholesterol-bearing macrophage foam cells in the initial stages of atherosclerosis serves as a characteristic feature of atherosclerotic lesions. The inhibitory effect of Siegesbeckia glabrescens, a species of flowering plant in the Asteraceae family, on foam cell formation in THP-1 macrophages has not yet been elucidated. In this study, we explored the effect of S. glabrescens ethanol extract (SGEE) and hot water extract (SGWE) on foam cell formation via co-treatment with oxidized low density lipoprotein (ox-LDL) and lipopolysaccharide (LPS), mimicking the occurrence of atherosclerosis in vitro, and studied the regulation of its underlying mechanisms. THP-1 cells differentiated by PMA (1 μM) for 48 h were subsequently treated with/without SGWE and SGEE for 48 h. THP-1 macrophages were treated with ox-LDL (20 μg/mL) and LPS (500 ng/mL) for 24 h. Treatment with ox-LDL and LPS for 24 h enhanced the lipid accumulation in foam cells compared to in untreated cells, as determined by oil red O staining. In contrast, SGWE and SGEE treatment inhibited lipid accumulation in foam cells. Both extracts significantly upregulated ABCA1, LXRα, and PPARγ expression in ox-LDL- and LPS-treated cells (P<0.05). Moreover, both SGWE and SGEE decreased LOX-1, CD36, and SR-A1 expression. The co-treatment of ox-LDL and LPS increased NF-κB, COX-2, and pro-inflammatory activation and expression compared with untreated cells. However, this increase suppressed NF-κB, COX-2, and pro-inflammatory expression by SGWE and SGEE. The results indicated that both extracts can partially inhibit foam cell formation and contribute to protective effects by suppressing cholesterol accumulation during the onset of atherosclerosis.

Comparison of the difference in the anti-inflammatory activity of two different color types of Farfarae Flos based on in vitro, in vivo experiments and untargeted metabolomics

Introduction

Due to its remarkable anti-inflammatory pharmacological activity, Farfarae Flos has gained extensive usage in the treatment of various inflammatory diseases such as bronchitis, pneumonia, prostatitis and colitis. And Farfarae Flos come in two color types depending on the color of the flowers: yellowish-white (YW), and purplish-red (PR). However, the difference in anti-inflammatory activity and metabolic profiles between the two flower colors remains unexplored.

Methods

This study aims to explore the difference in the anti-inflammatory potential between YW and PR variants of Farfarae Flos and unravel the mechanisms responsible for the observed differences in anti-inflammatory activity through an integrated approach encompassing untargeted metabolomics and in vivo/vitro experimental studies. Initially, we verified the contrasting effects of YW and PR on the inhibition of the inflammatory factors interleukin-6 (IL-6) and nitric oxide (NO) by utilizing an in vitro RAW 264.7 cell inflammation model. Subsequently, a comprehensive evaluation of the systemic inhibitory capacity of YW and PR on IL-6, Interleukin-10 (IL-10), and tumor necrosis factor-α (TNF-α) was conducted using a validated whole-body mouse model, followed by the analysis of inflammatory factors and histological examination of collected serum, liver, and spleen after 7 days. Furthermore, non-targeted metabolomics profiling was employed to analyze the metabolite profiles of Farfarae Flos with different colors, and quantitative analysis was conducted to identify differential metabolites between YW and PR. The correlation between the anti-inflammatory activities of differentially accumulated metabolites (DAMs) and Farfarae Flos was investigated, resulting in the identification of 48 compounds exhibiting significant anti-inflammatory activity. Additionally, KEGG pathway enrichment analysis was performed to elucidate the underlying mechanisms.

Results

Our findings demonstrate that both YW and PR possess anti-inflammatory abilities, with PR exhibiting significantly superior efficacy. The integration of in vivo/vitro experiments and non-targeted metabolomics confirmed the exceptional anti-inflammatory potential of PR and solidified its classification as the "purplish-red better" of Farfarae Flos.

Discussion

This study provides valuable insights into the breeding and medical transformation of Farfarae Flos varieties, along with a scientific basis for the establishment of quality standards and the development of new drugs utilizing Farfarae Flos.

Valosin-containing protein: A potential therapeutic target for cardiovascular diseases

Valosin-containing protein (VCP), also known as p97, plays a crucial role in various cellular processes, including protein degradation, endoplasmic reticulum-associated degradation, and cell cycle regulation. While extensive research has been focused on VCP's involvement in protein homeostasis and its implications in neurodegenerative diseases, emerging evidence suggests a potential link between VCP and cardiovascular health. VCP is a key regulator of mitochondrial function, and its overexpression or mutations lead to pathogenic diseases and cellular stress responses. The present review explores VCP's roles in numerous cardiovascular disorders including myocardial ischemia/reperfusion injury, cardiac hypertrophy, and heart failure. The review dwells on the roles of VCP in modifying mitochondrial activity, promoting S-nitrosylation, regulating mTOR signalling and demonstrating cardioprotective effects. Further research into VCP might lead to novel interventions for cardiovascular disease, particularly those involving ischemia/reperfusion injury and hypertrophy.

Single-cell transcriptome and crosstalk analysis reveals immune alterations and key pathways in the bone marrow of knee OA patients

Knee osteoarthritis (OA) is a significant medical and economic burden. To understand systemic immune effects, we performed deep exploration of bone marrow aspirate concentrates (BMACs) from knee-OA patients via single-cell RNA sequencing and proteomic analyses from a randomized clinical trial (MILES: NCT03818737). We found significant cellular and immune alterations in the bone marrow, specifically in MSCs, T cells and NK cells, along with changes in intra-tissue cellular crosstalk during OA progression. Unlike previous studies focusing on injury sites or peripheral blood, our probe into the bone marrow-an inflammation and immune regulation hub-highlights remote organ impact of OA, identifying cell types and pathways for potential therapeutic targeting. Our findings highlight increased cellular senescence and inflammatory pathways, revealing key upstream genes, transcription factors, and ligands. Additionally, we identified significant enrichment in key biological pathways like PI3-AKT-mTOR signaling and IFN responses, showing their potentially crucial role in OA onset and progression.

Unveiling the macrophage dynamics in osteoarthritic joints: From inflammation to therapeutic strategies

Osteoarthritis (OA) is an incurable, painful, and debilitating joint disease affecting over 500 million people worldwide. The OA joint tissues are infiltrated by various immune cells, particularly macrophages, which are able to induce or perpetuate inflammation. Notably, synovitis and its macrophage component represent a target of interest for developing treatments. In this review, we describe the latest advances in understanding the heterogeneity of macrophage origins, phenotypes, and functions in the OA joint and the effect of current symptomatic therapies on these cells. We then highlight the therapeutic potential of anticytokines/chemokines, nano- and microdrug delivery, and future strategies to modulate macrophage functions in OA.

Acetylation of TIR domains in the TLR4-Mal-MyD88 complex regulates immune responses in sepsis

Activation of the Toll-like receptor 4 (TLR4) by bacterial endotoxins in macrophages plays a crucial role in the pathogenesis of sepsis. However, the mechanism underlying TLR4 activation in macrophages is still not fully understood. Here, we reveal that upon lipopolysaccharide (LPS) stimulation, lysine acetyltransferase CBP is recruited to the TLR4 signalosome complex leading to increased acetylation of the TIR domains of the TLR4 signalosome. Acetylation of the TLR4 signalosome TIR domains significantly enhances signaling activation via NF-κB rather than IRF3 pathways. Induction of NF-κB signaling is responsible for gene expression changes leading to M1 macrophage polarization. In sepsis patients, significantly elevated TLR4-TIR acetylation is observed in CD16+ monocytes combined with elevated expression of M1 macrophage markers. Pharmacological inhibition of HDAC1, which deacetylates the TIR domains, or CBP play opposite roles in sepsis. Our findings highlight the important role of TLR4-TIR domain acetylation in the regulation of the immune responses in sepsis, and we propose this reversible acetylation of TLR4 signalosomes as a potential therapeutic target for M1 macrophages during the progression of sepsis.

Causal role of immune cells in diabetic nephropathy: a bidirectional Mendelian randomization study

Background

Diabetic nephropathy (DN) stands as a pervasive chronic renal disease worldwide, emerging as the leading cause of renal failure in end-stage renal disease. Our objective is to pinpoint potential immune biomarkers and evaluate the causal effects of prospective therapeutic targets in the context of DN.

Methods

We employed Mendelian randomization (MR) analysis to examine the causal associations between 731 immune cell signatures and the risk of DN. Various analytical methods, including inverse-variance weighted (IVW), MR-Egger, weighted median, simple mode, and weighted mode, were employed for the analysis. The primary analytical approach utilized was the inverse-variance weighted (IVW) method. To ensure the reliability of our findings, we conducted comprehensive sensitivity analyses to assess the robustness, heterogeneity, and presence of horizontal pleiotropy in the results. Statistical powers were also calculated. Ultimately, a reverse Mendelian randomization (MR) analysis was conducted to assess the potential for reverse causation.

Results

After Benjamini & Hochberg (BH) correction, four immunophenotypes were identified to be significantly associated with DN risk: HLA DR on Dendritic Cell (OR=1.4460, 95% CI = 1.2904~1.6205, P=2.18×10-10, P.adjusted= 1.6×10-7), HLA DR on CD14+ CD16- monocyte (OR=1.2396, 95% CI=1.1315~1.3580, P=3.93×10-6, P.adjusted = 0.00143). HLA DR on CD14+ monocyte (OR=1.2411, 95% CI=1.12957~1.3637, P=6.97×10-6, P.adjusted=0.0016), HLA DR on plasmacytoid Dendritic Cell (OR=1.2733, 95% CI= 1.1273~1.4382, P= 0.0001, P.adjusted = 0.0183). Significant heterogeneity of instrumental variables was found in the four exposures, and significant horizontal pleiotropy was only found in HLA DR on Dendritic Cell. The bidirectional effects between the immune cells and DN were not supported.

Conclusion

Our research illustrated the intimate association between immune cells and DN, which may contribute to a deeper understanding of the intricate mechanisms underlying DN and aid in the identification of novel intervention target pathways.

Single-cell transcriptomic landscape reveals the role of intermediate monocytes in aneurysmal subarachnoid hemorrhage

Objective

Neuroinflammation is associated with brain injury and poor outcomes after aneurysmal subarachnoid hemorrhage (SAH). In this study, we performed single-cell RNA sequencing (scRNA-seq) to analyze monocytes and explore the mechanisms of neuroinflammation after SAH.

Methods

We recruited two male patients with SAH and collected paired cerebrospinal fluid (CSF) and peripheral blood (PB) samples from each patient. Mononuclear cells from the CSF and PB samples were sequenced using 10x Genomics scRNA-seq. Additionally, scRNA-seq data for CSF from eight healthy individuals were obtained from the Gene Expression Omnibus database, serving as healthy controls (HC). We employed various R packages to comprehensively study the heterogeneity of transcriptome and phenotype of monocytes, including monocyte subset identification, function pathways, development and differentiation, and communication interaction.

Results

(1) A total of 17,242 cells were obtained in this study, including 7,224 cells from CSF and 10,018 cells from PB, mainly identified as monocytes, T cells, B cells, and NK cells. (2) Monocytes were divided into three subsets based on the expression of CD14 and CD16: classical monocytes (CM), intermediate monocytes (IM), and nonclassical monocytes (NCM). Differentially expressed gene modules regulated the differentiation and biological function in monocyte subsets. (3) Compared with healthy controls, both the toll-like receptor (TLR) and nod-like receptor (NLR) pathways were significantly activated and upregulated in IM from CSF after SAH. The biological processes related to neuroinflammation, such as leukocyte migration and immune response regulation, were also enriched in IM. These findings revealed that IM may play a key role in neuroinflammation by mediating the TLR and NLR pathways after SAH.

Interpretation

In conclusion, we establish a single-cell transcriptomic landscape of immune cells and uncover the heterogeneity of monocyte subsets in SAH. These findings offer new insights into the underlying mechanisms of neuroinflammation and therapeutic targets for SAH.

Acute blood loss in mice forces differentiation of both CD45-positive and CD45-negative erythroid cells and leads to a decreased CCL3 chemokine production by bone marrow erythroid cells

Hemorrhage, a condition that accompanies most physical trauma cases, remains an important field of study, a field that has been extensively studied in the immunological context for myeloid and lymphoid cells, but not as much for erythroid cells. In this study, we studied the immunological response of murine erythroid cells to acute blood loss using flow cytometry, NanoString immune transcriptome profiling, and BioPlex cytokine secretome profiling. We observed that acute blood loss forces the differentiation of murine erythroid cells in both bone marrow and spleen and that there was an up-regulation of several immune response genes, in particular pathogen-associated molecular pattern sensing gene Clec5a in post-acute blood loss murine bone marrow erythroid cells. We believe that the up-regulation of the Clec5a gene in bone marrow erythroid cells could help bone marrow erythroid cells detect and eliminate pathogens with the help of reactive oxygen species and antimicrobial proteins calprotectin and cathelicidin, the genes of which (S100a8, S100a9, and Camp) dominate the expression in bone marrow erythroid cells of mice.

Transcriptomic responses of peripheral blood leukocytes to cardiac surgery after acute inflammation, and three months recovery

Traumatic perioperative conditions may trigger early systemic responses, activate leukocytes and reprogram the immune system. We hypothesize that leukocyte activation may not revert to pre-surgical states, and that protracted activation may emerge with increased risks of comorbidities. We tested this concept by examining the transcriptomes of monocytes and T cells in a representative observational cohort of patients (n = 13) admitted for elective cardiac surgery. Transcriptomes in T cells and monocytes were compared from before surgery (t0), and monocytes were analyzed longitudinally after acute (t24hr), and convalescent (t3m) time points. Monocytes and T cells expressed distinct transcriptomes, reflected by statistically significant differential expression of 558 T cell related genes. Monocytes expressed genes related to protein degradation and presented atypical activation of surface markers and cytoplasmic functions over time. Additionally, monocytes exhibited limited transcriptomic heterogeneity prior to surgery, and long-term patterns of gene expression associated with atherosclerosis showed three temporally distinct signatures. These data establish that post-cardiac surgery transcriptomes of monocytes differ even at three months compared to baselines, which may reflect latent ('smoldering') inflammation and persistent progression of tissue degenerative processes that should inform clinical care.

Spleen derived monocytes regulate pulmonary vascular permeability in Hepatopulmonary syndrome through the OSM-FGF/FGFR1 signaling

Hepatopulmonary syndrome (HPS) is a serious pulmonary complication in the advanced stage of liver disease. The occurrence of pulmonary edema in HPS patients is life-threatening. Increased pulmonary vascular permeability is an important mechanism leading to pulmonary edema, and endothelial glycocalyx (EG) is a barrier that maintains stable vascular permeability. However, in HPS, whether the pulmonary vascular EG changes and its regulatory mechanism are still unclear. Spleen derived monocytes are involved in the pathogenesis of HPS. However, whether they regulate the pulmonary vascular permeability in HPS patients or rats and what is the mechanism is still unclear. Healthy volunteers and HPS patients with splenectomy or not were enrolled in this study. We found that the respiration of HPS patients was significantly improved in response to splenectomy, while the EG degradation and pulmonary edema were aggravated. In addition, HPS patients expressed higher levels of oncostatin M (OSM) and fibroblast growth factor (FGF). Subsequently, the co-culture system of monocytes and human umbilical vein endothelial cells (HUVECs) was constructed. It was found that monocytes secreted OSM and activated the FGF/FGFR1 signaling pathway in HUVECs. Then, an HPS rat model was constructed by common bile duct ligation (CBDL) for in vivo verification. HPS rats were intravenously injected with OSM recombinant protein and/or TNF-α into the rats via tail vein 30 min before CBDL. The results showed that the respiration of HPS rats was improved after splenectomy, while the degradation of EG in pulmonary vessels and vascular permeability were increased, and pulmonary edema was aggravated. Moreover, the expression of OSM and FGF was upregulated in HPS rats, while both were downregulated after splenectomy. Intravenous injection of exogenous OSM eliminated the effect of splenectomy on FGF and improved EG degradation. It can be seen that during HPS, spleen-derived monocytes secrete OSM to promote pulmonary vascular EG remodeling by activating the FGF/FGFR1 pathway, thereby maintaining stable vascular permeability, and diminishing pulmonary edema. This study provides a promising therapeutic target for the treatment of HPS.

A 38-colour high dimensional immunophenotyping panel for human peripheral blood mononuclear cells

High dimensional immunophenotyping panels are invaluable resources for performing extensive phenotyping on peripheral blood mononuclear cells (PBMCs). We designed a 38-colour high dimensional phenotyping panel to measure innate (monocytes, dendritic cells, NK cells, basophils, innate like lymphoid cells), T cell (γδ T cells, MAIT cells, CD4 and CD8 memory, Th1, Th2, Th17, Tfh, Treg) and B cell (memory, plasma cells, transitional B cells, plasmablasts, IgG, IgM) subsets in addition to their activation status using the 5-laser Cytek Aurora. We optimised optimal fluorochrome combinations and titres to minimise spread and autofluorescence of rare immune cell populations and tested this panel on PBMCs from 15 healthy adults. This high dimensional panel will be invaluable for direct ex vivo studies to evaluate immune cells in the context of human health and disease, especially when samples are limited.

Addition of CD14 improves discrimination of lymphocytes in the TBNK phenotyping panel

Peripheral blood lymphocyte phenotyping panels typically include CD45 for discrimination of the lymphocyte population, and fluorophore-conjugated monoclonal antibodies to identify T, B, and Natural Killer (NK) cells. While CD45 combined with side scatter is generally sufficient to clearly distinguish lymphocytes from monocytes in the majority of peripheral blood samples, it is challenging to accurately gate lymphocytes in samples from patients with monocytosis or significant lymphopenia, or from very young infants. Addition of a monocyte marker to lymphocyte phenotyping panels for monocyte exclusion has previously been evaluated for improved discrimination of lymphocytes, albeit largely in healthy donor adult samples. Here we evaluate the effect of the addition of CD14 to a standard lymphocyte phenotyping panel on total lymphocyte, T, B, and NK cell percentages in a predominantly pediatric population of patients under evaluation chiefly for immunodeficiency, immune-depletion, or immune reconstitution. Addition of CD14 to the standard lymphocyte phenotyping improved discrimination of lymphocytes from monocytes, resulted in decreased NK cell percentages, likely because CD16+ and/or CD56+ monocytes were included in the CD56+CD16+ NK cell gate with conventional gating, and although less significant, resulted in an increased percentage of B cells, since relatively larger B cells were likely gated out by more restrictive light scatter gating used with the conventional gating approach. The change in NK and B cell percentages were more pronounced in samples from patients below a year of age, and in patients who were relatively lymphopenic. These data suggest that addition of CD14 to conventional lymphocyte phenotyping panels that utilize CD45 versus side scatter gating results in significant improvement in the accuracy of lymphocyte gating, and accurate quantification of NK and B cells particularly in samples from infants and lymphopenic individuals.

Immunophenotyping and Therapeutic Insights from Chronic Mucocutaneous Candidiasis Cases with STAT1 Gain-of-Function Mutations

PURPOSE

Heterozygous STAT1 Gain-of-Function (GOF) mutations are the most common cause of chronic mucocutaneous candidiasis (CMC) among Inborn Errors of Immunity. Clinically, these mutations manifest as a broad spectrum of immune dysregulation, including autoimmune diseases, vascular disorders, and malignancies. The pathogenic mechanisms of immune dysregulation and its impact on immune cells are not yet fully understood. In treatment, JAK inhibitors have shown therapeutic effectiveness in some patients.

METHODS

We analyzed clinical presentations, cellular phenotypes, and functional impacts in five Taiwanese patients with STAT1 GOF.

RESULTS

We identified two novel GOF mutations in 5 patients from 2 Taiwanese families, presenting with symptoms of CMC, late-onset rosacea, and autoimmunity. The enhanced phosphorylation and delayed dephosphorylation were displayed by the patients' cells. There are alterations in both innate and adaptive immune cells, including expansion of CD38+HLADR +CD8+ T cells, a skewed activated Tfh cells toward Th1, reduction of memory, marginal zone and anergic B cells, all main functional dendritic cell lineages, and a reduction in classical monocyte. Baricitinib showed therapeutic effectiveness without side effects.

CONCLUSION

Our study provides the first comprehensive clinical and molecular characteristics in STAT1 GOF patient in Taiwan and highlights the dysregulated T and B cells subsets which may hinge the autoimmunity in STAT1 GOF patients. It also demonstrated the therapeutic safety and efficacy of baricitinib in pediatric patient. Further research is needed to delineate how the aberrant STAT1 signaling lead to the changes in cellular populations as well as to better link to the clinical manifestations of the disease.

Diet-Induced Obesity in Mice Affects the Maternal Gut Microbiota and Immune Response in Mid-Pregnancy

Maternal obesity during pregnancy is associated with adverse pregnancy outcomes. This might be due to undesired obesity-induced changes in the maternal gut microbiota and related changes in the maternal immune adaptations during pregnancy. The current study examines how obesity affects gut microbiota and immunity in pregnant obese and lean mice during mid-pregnancy (gestational day 12 (GD12)). C57BL/6 mice were fed a high-fat diet or low-fat diet from 8 weeks before mating and during pregnancy. At GD12, we analyzed the gut microbiota composition in the feces and immune responses in the intestine (Peyer's patches, mesenteric lymph nodes) and the peripheral circulation (spleen and peripheral blood). Maternal obesity reduced beneficial bacteria (e.g., Bifidobacterium and Akkermansia) and changed intestinal and peripheral immune responses (e.g., dendritic cells, Th1/Th2/Th17/Treg axis, monocytes). Numerous correlations were found between obesity-associated bacterial genera and intestinal/peripheral immune anomalies. This study shows that maternal obesity impacts the abundance of specific bacterial gut genera as compared to lean mice and deranges maternal intestinal immune responses that subsequently change peripheral maternal immune responses in mid-pregnancy. Our findings underscore the opportunities for early intervention strategies targeting maternal obesity, ideally starting in the periconceptional period, to mitigate these obesity-related pregnancy effects.

The significance of CD16+ monocytes in the occurrence and development of chronic thromboembolic pulmonary hypertension: insights from single-cell RNA sequencing

Background

Chronic thromboembolic pulmonary hypertension (CTEPH) is a serious pulmonary vascular disease characterized by residual thrombi in the pulmonary arteries and distal pulmonary microvascular remodeling. The pathogenesis of CTEPH remains unclear, but many factors such as inflammation, immunity, coagulation and angiogenesis may be involved. Monocytes are important immune cells that can differentiate into macrophages and dendritic cells and play an important role in thrombus formation. However, the distribution, gene expression profile and differentiation trajectory of monocyte subsets in CTEPH patients have not been systematically studied. This study aims to reveal the characteristics and functions of monocytes in CTEPH patients using single-cell sequencing technology, and to provide new insights for the diagnosis and treatment of CTEPH.

Methods

Single-cell RNA sequencing (scRNA-seq) were performed to analyze the transcriptomic features of peripheral blood mononuclear cells (PBMCs) from healthy controls, CTEPH patients and the tissues from CTEPH patients after the pulmonary endarterectomy (PEA). We established a CTEPH rat model with chronic pulmonary embolism caused by repeated injection of autologous thrombi through a central venous catheter, and used flow cytometry to detect the proportion changes of monocyte subsets in CTEPH patients and CTEPH rat model. We also observed the infiltration degree of macrophage subsets in thrombus tissue and their differentiation relationship with peripheral blood monocyte subsets by immunofluorescence staining.

Results

The results showed that the monocyte subsets in peripheral blood of CTEPH patients changed significantly, especially the proportion of CD16+ monocyte subset increased. This monocyte subset had unique functional features at the transcriptomic level, involving processes such as cell adhesion, T cell activation, coagulation response and platelet activation, which may play an important role in pulmonary artery thrombus formation and pulmonary artery intimal remodeling. In addition, we also found that the macrophage subsets in pulmonary endarterectomy tissue of CTEPH patients showed pro-inflammatory and lipid metabolism reprogramming features, which may be related to the persistence and insolubility of pulmonary artery thrombi and the development of pulmonary hypertension. Finally, we also observed that CD16+ monocyte subset in peripheral blood of CTEPH patients may be recruited to pulmonary artery intimal tissue and differentiate into macrophage subset with high expression of IL-1β, participating in disease progression.

Conclusion

CD16+ monocytes subset had significant gene expression changes in CTEPH patients, related to platelet activation, coagulation response and inflammatory response. And we also found that these cells could migrate to the thrombus and differentiate into macrophages with high expression of IL-1β involved in CTEPH disease progression. We believe that CD16+ monocytes are important participants in CTEPH and potential therapeutic targets.

The Role of Epigenetic Mechanisms in the Pathogenesis of Hepatitis C Infection

Hepatitis C virus (HCV) is a hepatotropic virus that can be transmitted through unsafe medical procedures, such as injections, transfusions, and dental treatment. The infection may be self-limiting or manifest as a chronic form that induces liver fibrosis, cirrhosis, or progression into hepatocellular carcinoma (HCC). Epigenetic mechanisms are major regulators of gene expression. These mechanisms involve DNA methylation, histone modifications, and the activity of non-coding RNAs, which can enhance or suppress gene expression. Abnormal activity or the dysregulated expression of epigenetic molecules plays an important role in the pathogenesis of various pathological disorders, including inflammatory diseases and malignancies. In this review, we summarise the current evidence on epigenetic mechanisms involved in HCV infection and progression to HCC.

MOCHA's advanced statistical modeling of scATAC-seq data enables functional genomic inference in large human cohorts

Single-cell assay for transposase-accessible chromatin using sequencing (scATAC-seq) is being increasingly used to study gene regulation. However, major analytical gaps limit its utility in studying gene regulatory programs in complex diseases. In response, MOCHA (Model-based single cell Open CHromatin Analysis) presents major advances over existing analysis tools, including: 1) improving identification of sample-specific open chromatin, 2) statistical modeling of technical drop-out with zero-inflated methods, 3) mitigation of false positives in single cell analysis, 4) identification of alternative transcription-starting-site regulation, and 5) modules for inferring temporal gene regulatory networks from longitudinal data. These advances, in addition to open chromatin analyses, provide a robust framework after quality control and cell labeling to study gene regulatory programs in human disease. We benchmark MOCHA with four state-of-the-art tools to demonstrate its advances. We also construct cross-sectional and longitudinal gene regulatory networks, identifying potential mechanisms of COVID-19 response. MOCHA provides researchers with a robust analytical tool for functional genomic inference from scATAC-seq data.

Altered co-stimulatory and inhibitory receptors on monocyte subsets in patients with visceral leishmaniasis

Visceral leishmaniasis (VL) is a neglected tropical disease caused by parasites from the Leishmania (L.) donovani complex. VL is characterised by uncontrolled parasite replication in spleen, liver and bone marrow, and by an impaired immune response and high systemic levels of inflammation. Monocytes have been poorly characterised in VL patients. The aim of this study was to evaluate the expression levels of markers involved in the regulation of T cell responses on different subsets of monocytes from the blood of VL patients and healthy non-endemic controls (HNEC). Monocytes can broadly be divided into three subsets: classical, intermediate and non-classical monocytes. Our results show that the percentages of all three subsets stayed similar at the time of VL diagnosis (ToD) and at the end of anti-leishmanial treatment (EoT). We first looked at co-stimulatory receptors: the expression levels of CD40 were significantly increased on classical and intermediate, but not non-classical monocytes, at ToD as compared to EoT and HNEC. CD80 expression levels were also increased on intermediate monocytes at ToD as compared to EoT and HNEC, and on classical monocytes only as compared to HNEC. The levels of CD86 were similar at EoT and ToD and in HNEC on classical and intermediate monocytes, but significantly higher at EoT on non-classical monocytes. We also looked at an inhibitory molecule, PD-L1. Our results show that the expression levels of PD-L1 were significantly higher on all three monocyte subsets at ToD as compared to HNEC, and to EoT on classical and intermediate monocytes. These results show that monocytes from the blood of VL patients upregulate both co-stimulatory and inhibitory receptors and that their expression levels are restored at EoT.

Myeloproliferative Neoplasms Transcriptome Reveals Pro-Inflammatory Signature and Enrichment in Peripheral Blood Monocyte-Related Genes

Myeloproliferative neoplasms (MPN) are hematological diseases associated with genetic driver mutations in the JAK2, CALR, and MPL genes and exacerbated oncoinflammatory status. Analyzing public microarray data from polycythemia vera (n = 41), essential thrombocythemia (n = 21), and primary myelofibrosis (n = 9) patients' peripheral blood by in silico approaches, we found that pro-inflammatory and monocyte-related genes were differentially expressed in MPN patients' transcriptome. Genes related to cell activation, secretion of pro-inflammatory and pro-angiogenic mediators, activation of neutrophils and platelets, coagulation, and interferon pathway were upregulated in monocytes compared to controls. Together, our results suggest that molecular alterations in monocytes may contribute to oncoinflammation in MPN.

Modelling the role of enzymatic pathways in the metabolism of docosahexaenoic acid by monocytes and its association with osteoarthritic pain

Chronic pain is a major cause of disability and suffering in osteoarthritis (OA) patients. Endogenous specialised pro-resolving molecules (SPMs) curtail pro-inflammatory responses. One of the SPM intermediate oxylipins, 17-hydroxydocasahexaenoic acid (17-HDHA, a metabolite of docosahexaenoic acid (DHA)), is significantly associated with OA pain. The aim of this multidisciplinary work is to develop a mathematical model to describe the contributions of enzymatic pathways (and the genes that encode them) to the metabolism of DHA by monocytes and to the levels of the down-stream metabolites, 17-HDHA and 14-hydroxydocasahexaenoic acid (14-HDHA), motivated by novel clinical data from a study involving 30 participants with OA. The data include measurements of oxylipin levels, mRNA levels, measures of OA severity and self-reported pain scores. We propose a system of ordinary differential equations to characterise associations between the different datasets, in order to determine the homeostatic concentrations of DHA, 17-HDHA and 14-HDHA, dependent upon the gene expression of the associated metabolic enzymes. Using parameter-fitting methods, local sensitivity and uncertainty analysis, the model is shown to fit well qualitatively to experimental data. The model suggests that up-regulation of some ALOX genes may lead to the down-regulation of 17-HDHA and that dosing with 17-HDHA increases the production of resolvins, which helps to down-regulate the inflammatory response. More generally, we explore the challenges and limitations of modelling real data, in particular individual variability, and also discuss the value of gathering additional experimental data motivated by the modelling insights.

LL37/self-DNA complexes mediate monocyte reprogramming

LL37 alone and in complex with self-DNA triggers inflammatory responses in myeloid cells and plays a crucial role in the development of systemic autoimmune diseases, like psoriasis and systemic lupus erythematosus. We demonstrated that LL37/self-DNA complexes induce long-term metabolic and epigenetic changes in monocytes, enhancing their responsiveness to subsequent stimuli. Monocytes trained with LL37/self-DNA complexes and those derived from psoriatic patients exhibited heightened glycolytic and oxidative phosphorylation rates, elevated release of proinflammatory cytokines, and affected naïve CD4+ T cells. Additionally, KDM6A/B, a demethylase of lysine 27 on histone 3, was upregulated in psoriatic monocytes and monocytes treated with LL37/self-DNA complexes. Inhibition of KDM6A/B reversed the trained immune phenotype by reducing proinflammatory cytokine production, metabolic activity, and the induction of IL-17-producing T cells by LL37/self-DNA-treated monocytes. Our findings highlight the role of LL37/self-DNA-induced innate immune memory in psoriasis pathogenesis, uncovering its impact on monocyte and T cell dynamics.

Maternal Innate Immune Reprogramming After Complicated Pregnancy

PROBLEM

Preeclampsia (PE) and fetal growth restriction (FGR) are often associated with maternal inflammation and an increased risk of cardiovascular and metabolic disease in the affected mothers. The mechanism responsible for this increased risk of subsequent disease may involve reprogramming of innate immune cells, characterized by epigenetic modifications.

METHOD OF STUDY

Circulating monocytes from women with PE, FGR, or uncomplicated pregnancies (control) were isolated before labor. Cytokine release from monocytes following exposure to lipopolysaccharide (LPS) and the presence of lysine 4-trimethylated histone 3 (H3K4me3) within TNF promoter sequences were evaluated. Single-cell transcriptomic profiles of circulating monocytes from women with PE or uncomplicated pregnancies were assessed.

RESULTS

Monocytes from women with PE or FGR exhibited increased IL-10 secretion and decreased IL-1β and GM-CSF secretion in response to LPS. While TNFα secretion was not significantly different in cultures of control monocytes versus those from complicated pregnancies with or without LPS exposure, monocytes from complicated pregnancies had significantly decreased levels of H3K4me3 associated with TNF promoter sequences. Cluster quantification and pathway analysis of differentially expressed genes revealed an increased proportion of anti-inflammatory myeloid cells and a lower proportion of inflammatory non-classical monocytes among the circulating monocyte population in women with PE.

CONCLUSIONS

Monocytes from women with PE and FGR exhibit an immune tolerance phenotype before initiation of labor. Further investigation is required to determine whether this tolerogenic phenotype persists after the affected pregnancy and contributes to increased risk of subsequent disease.

TRANSCRIPTOMIC DIFFERENCES IN PERIPHERAL MONOCYTE POPULATIONS IN SEPTIC PATIENTS BASED ON OUTCOME

ABSTRACT

Postsepsis early mortality is being replaced by survivors who experience either a rapid recovery and favorable hospital discharge or the development of chronic critical illness with suboptimal outcomes. The underlying immunological response that determines these clinical trajectories remains poorly defined at the transcriptomic level. As classical and nonclassical monocytes are key leukocytes in both the innate and adaptive immune systems, we sought to delineate the transcriptomic response of these cell types. Using single-cell RNA sequencing and pathway analyses, we identified gene expression patterns between these two groups that are consistent with differences in TNF-α production based on clinical outcome. This may provide therapeutic targets for those at risk for chronic critical illness in order to improve their phenotype/endotype, morbidity, and long-term mortality.

CLADIN- CLADribine and INnate immune response in multiple sclerosis - A phase IV prospective study

Cladribine (Mavenclad®) is an oral treatment for relapsing remitting MS (RRMS), but its mechanism of action and its effects on innate immune responses in unknown. This study is a prospective Phase IV study of 41 patients with RRMS, and aims to investigate the mechanism of action of cladribine on peripheral monocytes, and its impact on the P2X7 receptor. There was a significant reduction in monocyte count in vivo at week 1 post cladribine administration, and the subset of cells being most impacted were the CD14lo CD16+ 'non-classical' monocytes. Of the 14 cytokines measured in serum, CCL2 levels increased at week 1. In vitro, cladrabine induced a reduction in P2X7R pore as well as channel activity. This study demonstrates a novel mechanism of action for cladribine. It calls for studying potential benefits of cladribine in progressive forms of MS and other neurodegenerative diseases where innate immune related inflammation is implicated in disease pathogenesis.

Increased Natural Killer (NK)-cell cytotoxicity and Trypanosoma cruzi-specific memory B cells in subjects with discordant serology for Chagas disease

The presence of memory T cell specific for Trypanosoma cruzi in subjects with discordant serology for Chagas disease supports a cleared infection in these subjects. Using high-dimensional flow cytometry, ELISPOT assays and quantitative PCR, antibody-secreting cells and memory B cells specific for T. cruzi, total B-cell phenotypes, innate immune responses and parasite DNA were evaluated in serodiscordant, seropositive and seronegative subjects for T. cruzi infection. T. cruzi-specific memory B cells but no antibody-secreting cells specific for T. cruzi, increased proportion of nonclassical monocytes and increased levels of polyfunctional NK cells were found in serodiscordant compared with seropositive subjects. None of the serodiscordant subjects evaluated showed detectable parasite DNA, most of them did not show cardiac abnormalities and a group of them had had confirmed positive serology for Chagas disease. The unique immune profiles in serodiscordant subjects support that T. cruzi infection was cleared or profoundly controlled in these subjects.

Circulating monocyte populations as biomarker for abdominal aortic aneurysms: a single-center retrospective cohort study

Background

Abdominal aortic aneurysm (AAA) development is driven by inflammation, in particular myeloid cells, which represent attractive biomarker candidates. Yet to date, the maximum aortic diameter is the only clinically applied predictor of AAA progression and indicator for surgical repair. We postulated that aortic inflammation is reflected in a systemic change of monocyte populations, which we investigated regarding marker potential in AAA diagnosis and prognosis.

Methods

We conducted a single-center retrospective cohort study in a diagnostic setting, measuring monocyte subsets by flow cytometry in peripheral blood samples of 47 AAA patients under surveillance, matched with 25 healthy controls and 25 patients with peripheral artery disease (PAD). In a prognostic setting, we acquired longitudinal data of 60 AAA patients including aneurysm growth assessment by computed tomography at 6-month intervals.

Results

Blood levels of total monocytes, CD16+ monocytes and particularly intermediate monocytes were significantly increased in AAA patients versus healthy individuals and were also elevated compared to PAD patients. The combination of intermediate monocyte and D-dimer blood levels outperformed the individual diagnostic marker values. Additionally, the elevated concentrations of total monocytes, intermediate monocytes, and monocyte-platelet aggregates (MPA) were suited to predict rapid AAA progression over short-term periods of six months. Of note, MPA were identified as independent predictor of AAA disease progression in multivariable analysis.

Conclusion

Circulating monocyte subsets are elevated in AAA patients and support diagnosis and prediction of aneurysm progression. Monocyte subsets and D-dimer reflect different hallmarks (inflammation and hemostasis) of AAA pathology and when combined, may serve as improved biomarker.

The immunoregulatory role of monocytes and thrombomodulin in myelodysplastic neoplasms

Myelodysplastic neoplasms (MDS) are clonal disorders of the myeloid lineage leading to peripheral blood cytopenias. Dysregulation of innate immunity is hypothesized to be a potent driver of MDS. A recent study revealed increased thrombomodulin (TM) expression on classical monocytes in MDS, which was associated with prolonged survival. TM is a receptor with immunoregulatory capacities, however, its exact role in MDS development remains to be elucidated. In this review we focus on normal monocyte biology and report on the involvement of monocytes in myeloid disease entities with a special focus on MDS. Furthermore, we delve into the current knowledge on TM and its function in monocytes in health and disease and explore the role of TM-expressing monocytes as driver, supporter or epiphenomenon in the MDS bone marrow environment.

A subpopulation of human bone marrow erythroid cells displays a myeloid gene expression signature similar to that of classic monocytes

Erythroid cells, serving as progenitors and precursors to erythrocytes responsible for oxygen transport, were shown to exhibit an immunosuppressive and immunoregulatory phenotype. Previous investigations from our research group have revealed an antimicrobial gene expression profile within murine bone marrow erythroid cells which suggested a role for erythroid cells in innate immunity. In the present study, we focused on elucidating the characteristics of human bone marrow erythroid cells through comprehensive analyses, including NanoString gene expression profiling utilizing the Immune Response V2 panel, a BioPlex examination of chemokine and TGF-beta family proteins secretion, and analysis of publicly available single-cell RNA-seq data. Our findings demonstrate that an erythroid cell subpopulation manifests a myeloid-like gene expression signature comprised of antibacterial immunity and neutrophil chemotaxis genes which suggests an involvement of human erythroid cells in the innate immunity. Furthermore, we found that human erythroid cells secreted CCL22, CCL24, CXCL5, CXCL8, and MIF chemokines. The ability of human erythroid cells to express these chemokines might facilitate the restriction of immune cells in the bone marrow under normal conditions or contribute to the ability of erythroid cells to induce local immunosuppression by recruiting immune cells in their immediate vicinity in case of extramedullary hematopoiesis.

Exploring the associations between elevated plasma SP-D levels and OSCAR gene expression as potential biomarkers in patients with COPD: a cross-sectional study

Background: Chronic obstructive pulmonary disease (COPD) imposes a substantial burden on patients and healthcare systems. Spirometry is the most widely used test to diagnose the disease; however, a surrogate marker is required to predict the disease pattern and progression. Objectives: The aim of the current study was to explore the association of elevated levels of plasma surfactant protein D (SP-D) with gene expression of osteoclast-associated receptor (OSCAR) and lung functions as potential diagnostic biomarkers of COPD. Methods: This cross-sectional study employed convenience sampling. As men compose the majority of patients in the outpatient department and with smoking being common among Pakistani men, choosing men offered a representative sample. Using a post-bronchodilator forced expiratory volume in the first second (FEV1) to a forced vital capacity (FVC) of less than 0.70 (FEV1/FVC <0.7), COPD patients were diagnosed on spirometry (n = 41). Controls were healthy individuals with FEV1/FVC >0.7 (n = 41). Plasma SP-D levels were measured using an enzyme-linked immunosorbent assay (ELISA). The gene expression of OSCAR was determined by real-time polymerase chain reaction (qPCR) and subsequently analyzed by the threshold cycle (Ct) method. Statistical Package for Social Sciences (SPSS) version 20 was used for statistical analysis. Results: The mean BMI of controls (25.66 ± 4.17 kg/m2) was higher than that of cases (23.49 ± 2.94 kg/m2 (p = .008)). The median age of controls was 49 years (interquartile range (IQR) 42.0-65.0 years) and that of cases was 65 years (IQR = 57.50-68.50). SP-D concentration was not significantly higher in COPD patients [4.96 ng/mL (IQR 3.26-7.96)] as compared to controls [3.64 ng/mL (IQR 2.60-8.59)] (p = .209). The forced expiratory ratio (FEV1/FVC) and FEV1 were related to gene expression of OSCAR (p = <.001). The gene expression of OSCAR was significantly related to SP-D (p = .034). A multiple regression model found FEV1 and FVC to have a significant effect on the gene expression of OSCAR (p-values <0.001 and 0.001, respectively). Conclusion: Gene expression of OSCAR was increased in COPD patients and related directly to SP-D levels and inversely to lung functions in cohort of this study, suggesting that OSCAR along with SP-D may serve as a diagnostic biomarker of COPD.

Obesity and diet independently affect maternal immunity, maternal gut microbiota and pregnancy outcome in mice

Introduction

Maternal obesity poses risks for both mother and offspring during pregnancy, with underlying mechanisms remaining largely unexplored. Obesity is associated with microbial gut dysbiosis and low-grade inflammation, and also the diet has a major impact on these parameters. This study aimed to investigate how maternal obesity and diet contribute to changes in immune responses, exploring potential associations with gut microbiota dysbiosis and adverse pregnancy outcomes in mice.

Methods

Before mating, C57BL/6 mice were assigned to either a high-fat-diet (HFD) or low-fat-diet (LFD) to obtain obese (n=17) and lean (n=10) mice. To distinguish between the effects of obesity and diet, 7 obese mice were switched from the HFD to the LFD from day 7 until day 18 of pregnancy ("switch group"), which was the endpoint of the study. T helper (Th) cell subsets were studied in the spleen, mesenteric lymph nodes (MLN) and Peyer's patches (PP), while monocyte subsets and activation status were determined in maternal blood (flow cytometry). Feces were collected before and during pregnancy (day 7,14,18) for microbiota analysis (16S rRNA sequencing). Pregnancy outcome included determination of fetal and placental weight.

Results

Obesity increased splenic Th1 and regulatory T cells, MLN Th1 and PP Th17 cells and enhanced IFN-γ and IL-17A production by splenic Th cells upon ex vivo stimulation. Switching diet decreased splenic and PP Th2 cells and classical monocytes, increased intermediate monocytes and activation of intermediate/nonclassical monocytes. Obesity and diet independently induced changes in the gut microbiota. Various bacterial genera were increased or decreased by obesity or the diet switch. These changes correlated with the immunological changes. Fetal weight was lower in the obese than the lean group, while placental weight was lower in the switch than the obese group.

Discussion

This study demonstrates that obesity and diet independently impact peripheral and intestinal immune responses at the end of pregnancy. Simultaneously, both factors affect specific bacterial gut genera and lead to reduced fetal or placental weight. Our data suggest that switching diet during pregnancy to improve maternal health is not advisable and it supports pre/probiotic treatment of maternal obesity-induced gut dysbiosis to improve maternal immune responses and pregnancy outcome.

Current Knowledge about Nonclassical Monocytes in Patients with Multiple Sclerosis, a Systematic Review

Monocytes play a critical role in the initiation and progression of multiple sclerosis (MS). Recent research indicates the importance of considering the roles of monocytes in the management of MS and the development of effective interventions. This systematic review examined published research on the roles of nonclassical monocytes in MS and how they influence disease management. Reputable databases, such as PubMed, EMBASE, Cochrane, and Google Scholar, were searched for relevant studies on the influence of monocytes on MS. The search focused on studies on humans and patients with experimental autoimmune encephalomyelitis (EAE) published between 2014 and 2024 to provide insights into the study topic. Fourteen articles that examined the role of monocytes in MS were identified; the findings reported in these articles revealed that nonclassical monocytes could act as MS biomarkers, aid in the development of therapeutic interventions, reveal disease pathology, and improve approaches for monitoring disease progression. This review provides support for the consideration of monocytes when researching effective diagnostics, therapeutic interventions, and procedures for managing MS pathophysiology. These findings may guide future research aimed at gaining further insights into the role of monocytes in MS.

A genome-wide CRISPR/Cas9 knockout screen identifies TMEM239 as an important host factor in facilitating African swine fever virus entry into early endosomes

African swine fever (ASF) is a highly contagious, fatal disease of pigs caused by African swine fever virus (ASFV). The complexity of ASFV and our limited understanding of its interactions with the host have constrained the development of ASFV vaccines and antiviral strategies. To identify host factors required for ASFV replication, we developed a genome-wide CRISPR knockout (GeCKO) screen that contains 186,510 specific single guide RNAs (sgRNAs) targeting 20,580 pig genes and used genotype II ASFV to perform the GeCKO screen in wild boar lung (WSL) cells. We found that knockout of transmembrane protein 239 (TMEM239) significantly reduced ASFV replication. Further studies showed that TMEM239 interacted with the early endosomal marker Rab5A, and that TMEM239 deletion affected the co-localization of viral capsid p72 and Rab5A shortly after viral infection. An ex vivo study showed that ASFV replication was significantly reduced in TMEM239-/- peripheral blood mononuclear cells from TMEM239 knockout piglets. Our study identifies a novel host factor required for ASFV replication by facilitating ASFV entry into early endosomes and provides insights for the development of ASF-resistant breeding.

Breast Cancer Immune Landscape: Interplay Between Systemic and Local Immunity

Breast cancer (BC) is one of the most common malignancies in women worldwide. Numerous studies in immuno-oncology and successful trials of immunotherapy have demonstrated the causal role of the immune system in cancer pathogenesis. The interaction between the tumor and the immune system is known to have a dual nature. Despite cytotoxic lymphocyte activity against transformed cells, a tumor can escape immune surveillance and leverage chronic inflammation to maintain its own development. Research on antitumor immunity primarily focuses on the role of the tumor microenvironment, whereas the systemic immune response beyond the tumor site is described less thoroughly. Here, a comprehensive review of the formation of the immune profile in breast cancer patients is offered. The interplay between systemic and local immune reactions as self-sustaining mechanism of tumor progression is described and the functional activity of the main cell populations related to innate and adaptive immunity is discussed. Additionally, the interaction between different functional levels of the immune system and their contribution to the development of the pro- or anti-tumor immune response in BC is highlighted. The presented data can potentially inform the development of new immunotherapy strategies in the treatment of patients with BC.

VNN2-expressing circulating monocytes exhibit unique functional characteristics and are decreased in patients with primary Sjögren's syndrome

OBJECTIVE

This study aims to elucidate the significance of VNN2 expression in peripheral blood monocytes and its clinical relevance in primary Sjögren's syndrome (pSS).

METHODS

We investigated VNN2 expression by analyzing single-cell RNA sequencing (scRNA-seq) data from peripheral blood mononuclear cells. Flow cytometry was used to detect and compare VNN2 expression in total monocytes, classical monocytes (cMo), intermediate monocytes (iMo) and non-classical monocytes (ncMo). Additionally, we examined the expression of HLA, ICAM1, CD62L, ITGAM, S100A8, S100A9, CCR2, CCR6, CX3CR1 and CXCR3 in VNN2+ and VNN2- cells. We analyzed the correlation between VNN2 expression and clinical indicators and assessed the clinical utility of VNN2+ monocytes in pSS diagnosis using receiver operating characteristic curves.

RESULTS

We observed high VNN2 expression in monocytes, with significantly higher levels in CD14++ monocytes compared to ncMo. VNN2+ monocytes exhibited decreased expression of HLA and CD62L and increased expression of ICAM1, ITGAM, S100A8, S100A9, CCR2, CCR6, CX3CR1 and CXCR3 compared to VNN2- monocytes. Although scRNA-seq data showed that VNN2 mRNA was upregulated, cell surface expression of VNN2 was decreased in monocytes from pSS patients compared to healthy controls. The reduced levels of VNN2+ monocyte subpopulations in pSS patients were negatively correlated with anti-ribosome antibody levels and positively correlated with complement 4 levels. Detection of VNN2 expression in monocytes can aid in the auxiliary diagnosis of pSS.

CONCLUSION

Monocytes expressing cell surface VNN2 are significantly reduced in pSS patients. This suggests a potential role for VNN2 in pSS development and its potential use as a diagnostic marker for pSS.

Association of elevated circulating monocyte-platelet aggregates with hypercoagulability in patients with nephrotic syndrome

BACKGROUND

Hypercoagulability emerges as a central pathological feature and clinical complication in nephrotic syndrome. Increased platelet activation and aggregability are closely related to hypercoagulability in nephrotic syndrome. Monocyte-platelet aggregates (MPAs) have been proposed to represent a robust biomarker of platelet activation. The aim of this study was to investigate levels of the circulating MPAs and MPAs with the different monocyte subsets to evaluate the association of MPAs with hypercoagulability in nephrotic syndrome.

METHODS

Thirty-two patients with nephrotic syndrome were enrolled. In addition, thirty-two healthy age and sex matched adult volunteers served as healthy controls. MPAs were identified by CD14 monocytes positive for CD41a platelets. The classical (CD14 + + CD16-, CM), the intermediate (CD14 + + CD16+, IM) and the non-classical (CD14 + CD16++, NCM) monocytes, as well as subset specific MPAs, were measured by flow cytometry.

RESULTS

Patients with nephrotic syndrome showed a higher percentage of circulating MPAs as compared with healthy controls (p < 0.001). The percentages of MPAs with CM, IM, and NCM were higher than those of healthy controls (p = 0.012, p < 0.001 and p < 0.001, respectively). Circulating MPAs showed correlations with hypoalbuminemia (r=-0.85; p < 0.001), hypercholesterolemia (r = 0.54; p < 0.001), fibrinogen (r = 0.70; p < 0.001) and D-dimer (r = 0.37; p = 0.003), but not with hypertriglyceridemia in nephrotic syndrome. The AUC for the prediction of hypercoagulability in nephrotic syndrome using MPAs was 0.79 (95% CI 0.68-0.90, p < 0.001). The sensitivity of MPAs in predicting hypercoagulability was 0.71, and the specificity was 0.78.

CONCLUSION

Increased MPAs were correlated with hypercoagulability in nephrotic syndrome. MPAs may serve as a potential biomarker for thrombophilic or hypercoagulable state and provide novel insight into the mechanisms of anticoagulation in nephrotic syndrome.

Extracellular vesicles as modulators of monocyte and macrophage function in tumors

The tumor microenvironment (TME) harbors several cell types, such as tumor cells, immune cells, and non-immune cells. These cells communicate through several mechanisms, such as cell-cell contact, cytokines, chemokines, and extracellular vesicles (EVs). Tumor-derived vesicles are known to have the ability to modulate the immune response. Monocytes are a subset of circulating innate immune cells and play a crucial role in immune surveillance, being recruited to tissues where they differentiate into macrophages. In the context of tumors, it has been observed that tumor cells can attract monocytes to the TME and induce their differentiation into tumor-associated macrophages with a pro-tumor phenotype. Tumor-derived EVs have emerged as essential structures mediating this process. Through the transfer of specific molecules and signaling factors, tumor-derived EVs can shape the phenotype and function of monocytes, inducing the expression of cytokines and molecules by these cells, thus modulating the TME towards an immunosuppressive environment.

Disease activity drives divergent epigenetic and transcriptomic reprogramming of monocyte subpopulations in systemic lupus erythematosus

OBJECTIVES

Systemic lupus erythematosus (SLE) is characterised by systemic inflammation involving various immune cell types. Monocytes, pivotal in promoting and regulating inflammation in SLE, differentiate from classic monocytes into intermediate and non-classic monocytes, assuming diverse roles and changing their proportions in inflammation. In this study, we investigated the epigenetic and transcriptomic profiles of these and novel monocyte subsets in SLE in relation to activity and progression.

METHODS

We obtained the DNA methylomes and transcriptomes of classic, intermediate, non-classic monocytes in patients with SLE (at first and follow-up visits) and healthy donors. We integrated these data with single-cell transcriptomics of SLE and healthy donors and interrogated their relationships with activity and progression.

RESULTS

In addition to shared DNA methylation and transcriptomic alterations associated with a strong interferon signature, we identified monocyte subset-specific alterations, especially in DNA methylation, which reflect an impact of SLE on monocyte differentiation. SLE classic monocytes exhibited a proinflammatory profile and were primed for macrophage differentiation. SLE non-classic monocytes displayed a T cell differentiation-related phenotype, with Th17-regulating features. Changes in monocyte proportions, DNA methylation and expression occurred in relation to disease activity and involved the STAT pathway. Integration of bulk with single-cell RNA sequencing datasets revealed disease activity-dependent expansion of SLE-specific monocyte subsets, further supported the interferon signature for classic monocytes, and associated intermediate and non-classic populations with exacerbated complement activation.

CONCLUSIONS

Disease activity in SLE drives a subversion of the epigenome and transcriptome programme in monocyte differentiation, impacting the function of different subsets and allowing to generate predictive methods for activity and progression.

Dissecting and Visualizing the Functional Diversity of Cardiac Macrophages

Cardiac macrophages represent a functionally diverse population of cells involved in cardiac homeostasis, repair, and remodeling. With recent advancements in single-cell technologies, it is possible to elucidate specific macrophage subsets based on transcriptional signatures and cell surface protein expression to gain a deep understanding of macrophage diversity in the heart. The use of fate-mapping technologies and parabiosis studies have provided insight into the ontogeny and dynamics of macrophages identifying subsets derived from embryonic and adult definitive hematopoietic progenitors that include tissue-resident and bone marrow monocyte-derived macrophages, respectively. Within the heart, these subsets have distinct tissue niches and functional roles in the setting of homeostasis and disease, with cardiac resident macrophages representing a protective cell population while bone marrow monocyte-derived cardiac macrophages have a context-dependent effect, triggering both proinflammatory tissue injury, but also promoting reparative functions. With the increased understanding of the clinical relevance of cardiac macrophage subsets, there has been an increasing need to detect and measure cardiac macrophage compositions in living animals and patients. New molecular tracers compatible with positron emission tomography/computerized tomography and positron emission tomography/ magnetic resonance imaging have enabled investigators to noninvasively and serially visualize cardiac macrophage subsets within the heart to define associations with disease and measure treatment responses. Today, advancements within this thriving field are poised to fuel an era of clinical translation.

Immunomodulatory effects of a cell processing device to ameliorate dysregulated hyperinflammatory disease states

Cell directed therapy is an evolving therapeutic approach to treat organ dysfunction arising from hyperinflammation and cytokine storm by processing immune cells in an extracorporeal circuit. To investigate the mechanism of action of the Selective Cytopheretic Device (SCD), in vitro blood circuits were utilized to interrogate several aspects of the immunomodulatory therapy. SCD immunomodulatory activity is due to its effects on circulating neutrophils and monocytes in a low ionized calcium (iCa, Ca2+) blood circuit. Activated neutrophils adhere to the SCD fibers and degranulate with release of the constituents of their exocytotic vesicles. Adhered neutrophils in the low iCa environment display characteristics of apoptotic senescence. These neutrophils are subsequently released and returned back to circulation, demonstrating a clear potential for in vivo feedback. For monocytes, SCD treatment results in the selective adhesion of more pro-inflammatory subsets of the circulating monocyte pool, as demonstrated by both cell surface markers and cytokine secretory rates. Once bound, over time a subset of monocytes are released from the membrane with a less inflammatory functional phenotype. Similar methods to interrogate mechanism in vitro have been used to preliminarily confirm comparable findings in vivo. Therefore, the progressive amelioration of circulating leukocyte activation and immunomodulation of excessive inflammation observed in SCD clinical trials to date is likely due to this continuous autologous leukocyte processing.

Platelet-derived sTLT-1 is associated with platelet-mediated inflammation in coronary artery disease patients

The development of coronary artery disease (CAD) depends heavily on platelet activation, and inflammation plays a major role in all stages of atherosclerosis. Platelet-specific soluble triggering receptor expressed on myeloid cells like transcript 1 (sTLT-1) facilitate clot formation and have been linked to chronic inflammation. In this study, we explored the role of platelet-derived sTLT-1 in platelet-mediated inflammation in CAD patients. Plasma levels of sTLT-1 were measured using enzyme-linked immunosorbent assay in CAD patients (n = 163) and healthy controls (n = 99). Correlation analysis was performed to determine the circulatory sTLT-1 levels with platelet activation markers, immune cells, and inflammatory cytokines/chemokines. Increased plasma sTLT-1 levels were observed in CAD patients compared with those in healthy controls (p < 0.0001). A positive correlation was observed between sTLT-1 and platelet activation markers (P-selectin, PAC-1), CD14++ CD16- cells (classical monocytes), Natural killer T (NKT) cells, and platelet-immune cell aggregates with monocytes, neutrophils, dendritic cells, CD11c+ cells, and NKT cells. In contrast, a significant negative correlation was observed with CD8 cells. Furthermore, a significant positive correlation was observed between sTLT-1 and inflammatory markers (TNF-α, IL-1β, IL-2, IL-6, IL-12p70, IL-18, CXCL-12, and CCL-11). Logistic regression analysis identified sTLT-1 and triglycerides as predictors of CAD. Receiver operating characteristic curve (ROC) analysis showed that sTLT-1 had a higher sensitivity and specificity for predicting CAD. Our findings suggest that platelet activation induces the release of sTLT-1 into the circulation in CAD patients, which aggregates with immune cells and enhances inflammatory responses.