Pro-inflammatory Macrophages Research Articles

Abstract 2033: Bone Marrow-Derived Macrophage Extracellular Vesicles From Diabetic Mice Suppress Angiogenic Properties In Endothelial Cells

Introduction: Peripheral artery disease (PAD), increased in diabetes, leads to mortality and disability. Diabetes promotes a proinflammatory macrophage phenotype that suppresses repair. Macrophage-derived extracellular vesicles (EVs) have been associated with tissue damage. We hypothesize that diabetes perturbs macrophage EV cargo, thereby contributing to impaired repair responses to PAD/ischemia. Methods: Unilateral ligation of the left femoral artery (FAL) was performed to induce hind limb ischemia (HLI) in diabetic Akita (C57BL/6-Ins2 Akita /J) vs. non-diabetic (NDM, C57BL/6J) male mice. Murine BMDMs were grown in Exo-free medium. Ultracentrifugation was used to isolate EVs. Western blotting, transmission electron microscopy (TEM) and ZetaView nanoparticle tracking analysis were used to characterize EV size, number, concentration, and morphology. We profiled EV microRNA (miRNA) and protein cargos from Akita vs. NDM BMDM mice. Results: BMDMs-EV size was similar in Akita and NDM mice (diameter, 20-200nm). TEM showed cup-shaped morphology. Western blot confirmed known positive and negative control exosomal markers. Comparing Akita vs. NDM BMDM EVs, a total of 3277 proteins were identified; 821 proteins were significantly differentially expressed. Enrichment analysis highlighted pathways predominantly related to oxidative stress, insulin signaling, actin cytoskeleton, CLEAR, lipid metabolism, phagosome maturation, RNA binding and DNA replication. A total of 912 EV miRNAs were identified; 39 were significantly up-regulated and 19 were down-regulated. Preliminary analysis links a number of them to endothelial function and angiogenesis. In vitro , endothelial tube formation was impaired in human iliac artery endothelial cells treated with diabetic vs. NDM BMDM EVs. BMDM treated with diabetic vs. WT EVs displayed increased expression of inflammatory genes (TNF, IL-6,) and reduced expression of mitochondrial complex I and complex II proteins. Conclusion: We identified microRNAs and distinct proteins from diabetic EVs as potential mediators of impaired endothelial function and resolution of inflammation. Targeting macrophage EVs composition might identify therapeutic approaches to prevent and treat PAD in diabetes.

Probiotics Mitigate Exercise Fatigue, Memory Deficits, Depression and Neuro/inflammation in a Mouse Model of Gulf War Illness

We have previously found learning/memory, exercise intolerance, metabolic disturbance, gut dysbiosis and deregulation of neuroinflammatory genes, suggesting a possible microbiota-gut-brain interaction in GWI pathology (Kozlova et al., 2022a PMID: 34710444; 2022b PMID: 34801513). Here, we tested the hypothesis that probiotic treatment (P) prevents GWI symptoms. Adult male C57Bl/6N mice were separated into 4 groups (n=16/group): GW receiving pyridostigmine bromide (8.7 mg/kg, PB, po), permethrin (1.3 mg/kg, PER, top), DEET (33%, top); CON/S (vehicle plus stress); CON/S+P and GW+P. Probiotic groups received a gut-protective probiotic (P) cocktail of L. reuteri, L. rhamnosus, L. casei, B. longum (po, 108 CFU/mL, 3 times/wk) for 2 wk prior to and during GW agent treatment and until sacrifice 5 months later. Fecal RT-qPCR showed colonization of all strains except L. rhamnosus after 6-7 doses when compared to saline sham. Colonization after GW agent exposure was strain-specific and varied with time post-exposure. On an exercise endurance (EE) test GW (but not GW+P) mice tired faster relative to CON/S at PT56 (p<0.05) but not at PT150. Repeat testing on the passive avoidance apparatus (15 wk after previous test) showed that GW but not GW+P mice displayed reduced latency to enter aversive chamber on day 1 of acquisition trials, indicating deficient memory (p<0.05). Depressive-like behavior (mean percent time spent mobile) on tail suspension test (TST) showed less time spent mobile for GW (p<0.05) but not GW+P mice than controls at PT50 (but not PT150). Probiotics protected against the GW-induced rise in liver C-reactive protein (CRP) (p<0.05) and brain interleukin-6 (IL-6) (p<0.05). Immunofluorescence probing in the hippocampal CA1 and dentate gyrus showed significantly greater counts of Iba-1 positive cells in GW (but not GW+P) vs CON/S (p<0.05). NeuN immunostaining on the same sections showed abnormal neuronal phenotype indicative of reorganized RNA in GW but not GW+P) vs CON/S (p<0.05). Multi-gene profiling of innate and adaptive immunity genes in brain homogenates (prefrontal cortex, hypothalamus, hippocampus) identified GW agent-induced deregulation (>1.5-fold; p<.05) of pro-inflammatory genes, i.e., upregulation of C5ar1 and Cxcl10 and downregulation of Tlr4; changes prevented by probiotic treatment. In the gut, M1 proinflammatory macrophages appeared to be more abundant in GW (but not GW+P) vs CON/S (p<0.05). We used 16S next generation sequencing to examine probiotic treatment effects on gut microbial communities. In combination, our findings indicate that GW mice can be used to model multi-symptom illness and support previous evidence that the underlying pathophysiology in GWI likely involve systemic, gut and neuroinflammation and bacterial dysbiosis. Importantly, we show for the first time that probiotic treatment protects against some GWI symptom domains. Further study is needed to uncover pathophysiological pathways through which the microbiota-gut-brain axis impacts gut and brain health and toxicant-related pathology. DoD grant GW-180072 to M.C.C. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Abstract 2055: Pyruvic Carboxylase In Macrophages Aggravates Atherosclerosis By Regulating Metabolism Reprogramming To Promote Inflammatory Responses Through Hif-1 Signal Pathway

Background: Atherosclerotic patients exhibit abnormal glucose metabolism. Pyruvic carboxylase (PC) is a key enzyme in glucose metabolism which converts pyruvate into oxaloacetate, an intermediate reactant in both gluconeogenesis and tricarboxylic acid cycle. However, the role of PC in atherosclerosis remains unclear. Aims: We aimed to explore a potential target in macrophage metabolism for atherosclerosis treatment. Methods: We generated macrophage-specific PC knockout mice ( PC M KO ) by crossbreeding the PC fl/fl mice with L yz 2 -cre mice expressing Cre-recombinase in macrophages. Bone marrow transplantation was conducted to generate PC fl/fl / Apoe -/- and PC M KO / Apoe -/- chimaera. Mice were administered with AAV- PCSK9 DY followed by a 12-week high-fat diet (HFD) to induce atherosclerosis. Results: PC was upregulated in macrophages of human and mice with atherosclerosis. Macrophage-specific PC deficiency mitigated HFD-induced atherosclerotic lesions in both Apoe -/- mice and mice injected with AAV- PCSK9 DY . PC deletion reduced reactive oxygen species overproduction and mitochondrial damage in macrophages. Transcriptomics revealed that PC activated the HIF-1 signal pathway by initiating metabolic reprogramming in macrophages. By preventing HIF-1α from proteasome degradation, PC induced nuclear translocation of HIF-1α in atherosclerotic aortic roots. HIF-1α stabilizer, dimethyloxalylglycine, reversed the anti-inflammatory effect of PC in macrophages exposed to hypoxia, whereas the inhibition of HIF-1α impeded the transformation of pro-inflammatory macrophages to anti-inflammatory macrophages induced by PC overexpression. Dimethyloxalylglycine reversed the beneficial effects of macrophage PC deficiency on atherosclerosis. Conclusion: Macrophage PC aggravates atherosclerosis by regulating metabolic reprogramming, thereby promoting inflammatory responses in macrophages through HIF-1 signal pathway.

NEURAL INFLAMMATION CONTRIBUTES TO VOLTAGE-GATED POTASSIUM CHANNELS DYSFUNCTION IN LUMBAR DORSAL ROOT GANGLIA IN CHRONIC HEART FAILURE RATS

Objective: Skeletal muscle afferent sensitization causes excessive sympatho-excitation and exercise intolerance during physical activity in the chronic heart failure (CHF) state. Our recent study reported that downregulated voltage-gated potassium (Kv) channels in lumbar dorsal root ganglia (DRGs) contribute to muscle afferent sensitization in CHF rats. However, the cellular mechanisms underlying downregulated Kv channels in CHF remain unknown. We hypothesized that chronic macrophage activation contributes to Kv channels dysfunction in the lumbar DRGs in CHF. Design and method: Myocardial infarction (MI) was produced by left coronary artery ligation in rats. Molecular experiments were carried out to assess macrophage activation, cytokines and Kv channel expression in L4-L6 DRGs post MI. In vitro co-culture of lipopolysaccharide (LPS)-pretreated RAW264.7 (activated M1 macrophage) with 50B11 DRG neurons were performed. Patch clamp experiments were performed to assess Kv channel activity in acutely isolated muscle afferent DRG neurons. Chronic oral administration of minocycline (Mino, 20 mg/kg/day) was used to suppress macrophage activation in L4-L6 DRGs. Results: Compared to sham rats, male MI rats exhibited a robust increase in the number of Iba1-positive macrophages and the protein expression of Interferon regulatory factor 8 (IRF8, a pro-inflammatory macrophage marker) in L4-L6 DRGs at 8 weeks post MI, which was largely prevented by Mino (Figure 1). SEM showed macrophage infiltration into lumbar DRGs 8 weeks post MI. PCR data suggested that the mRNA expressions of pro-inflammatory cytokines including IL1beta and IL6 in lumbar DRGs were significantly elevated in male rats at 8-weeks post MI compared to sham rats. Protein expression of Kv channels including Kv1.4, 3.4, 4.2 and 4.3, was significantly downregulated in male rat L4-L6 DRGs at 8 weeks post MI. This was largely attenuated by Mino. Patch clamp data demonstrated decreased Ito current in isolated male rat muscle afferent DRG neurons 8 weeks post MI, also attenuated by Mino. Moreover, LPS-pretreated BV2 cells or RAW264.7 (LPS was washed out 4 hours after exposure, co-cultured with 50B11 DRG neurons significantly downregulated several Kv isoforms in DRG neurons. Conclusions: Macrophage activation contributes to Kv channels dysfunction in lumbar DRGs in CHF male rats.

Modified Zhenwu Decoction suppresses chronic colitis via targeting macrophage CCR2/Fyn/p38 MAPK signaling axis

BackgroundUlcerative colitis (UC) is associated with intestinal macrophage infiltration due to disruption of the mucosal barrier and bacterial invasion. Therefore, it is crucial to identify therapeutic agents capable of attenuating the macrophage-induced inflammatory response to preserve mucosal homeostasis and immune tolerance. The modified Zhenwu decoction (CDD-2103) is a novel herbal formulation developed based on the principles of Traditional Chinese medicine. To date, there are no clinically approved herbal formulations for UC with a well-known mechanism of action on macrophages. PurposeThe objective of this study was to systematically investigate the inhibitory effect of the active fraction of CDD-2103 in a mouse model of chronic colitis and delineate the mechanisms underlying its inhibitory action. MethodsCDD-2103 was extracted into four fractions using organic solvents with increasing polarity. A chronic 49-day dextran sulfate sodium (DSS)-induced colitis mice model, closely resembling human clinical conditions, was used to examine the effect of CDD-2103 on chronic colitis. To confirm the effect of CDD-2103 on macrophages in this chronic colitis model, adoptive macrophage transfer and CCL2 supplementation were conducted. The mechanisms of action of CDD-2103 were further elucidated utilizing bone marrow-derived macrophages (BMDMs). Transcriptome analysis was conducted to gain insights into the underlying mechanism of action of CDD-2103 in BMDMs. ResultsOur in vitro and in vivo findings demonstrated that the ethanol-enriched fraction of CDD-2103 exhibited significant anti-inflammatory effects, leading to the suppression of colitis severity. This effect was associated with diminished accumulation of colonic macrophages in the lamina propria of CDD-2103-intervened colitis mice. Specifically, CDD-2103 inhibited CCR2/L2-mediated proinflammatory macrophage infiltration into the colon without affecting macrophage proliferation. Mechanistically, CDD-2103 inhibited Fyn expression-mediated p38 MAPK activation and subsequently suppressed CCR2 expression in BMDMs. ConclusionsCollectively, our study supports the potential use of CDD-2103 to limit macrophage infiltration, thereby reducing inflammation during UC treatment. CDD-2103 and the components in the ethanolic fraction are promising candidates for the development of novel drugs for UC management. Additionally, our study underscores Fyn-mediated CCR2 expression as a potential therapeutic target for the management of UC.

Metabolic Reprogramming of Human Macrophages by Sickle Cell Hemoglobin

BACKGROUND: Sickle cell disease is caused by a single nucleotide mutation in the β-globin gene, resulting in the substitution of valine for glutamic acid, polymerization of hemoglobin and sickling of red blood cells (RBCs) under low oxygen conditions causing chronic hemolysis, and organs damage. SCA is characterized by the presence of cell-free plasma hemoglobin. Organ damage is associated with chronic inflammation and pro-inflammatory macrophages phenotype. Typically, anti-inflammatory response is elicited by the phagocytosis of senescent RBCs and cell-free hemoglobin. We have demonstrated that treatment of human macrophages with sickle cell hemoglobin (HbS) leads to lysosome accumulation, autophagy activation, and pro-inflammatory phenotype. The propensity of mutant HbS to polymerize under low pH may promote lysosomal HbS polymer accumulation, hindering degradation, and inducing macrophage differentiation towards a pro-inflammatory state. The differentiation of macrophages into specific phenotypes is associated with significant metabolic reprogramming. HYPOTHESIS: We hypothesize that the uptake of HbS by human macrophages induces their metabolic reprogramming via mitochondrial remodeling. METHODS: Human THP-1 cells were differentiated into macrophages with PMA and treated with either purified HbS or normal hemoglobin (HbA). Mitochondria were detected with MitoTrackerTM Green FM dye, and mitochondrial ROS (mtROS) level was detected by Mito SOX Red Kit. Transmission electron microscopy imaging was performed at Talos 200X transmission electron microscope. EPView (Olympus) software was used for the structure analysis. Total RNA was isolated by Trizol and sequenced on an Illumina® NextSeq 500. Comparisons between treatments were conducted using Gene Set Enrichment Analysis (GSEA). RESULTS: Immunofluorescent staining demonstrated accumulation of mitochondria after treatment with HbS compared to untreated (ctrl) or HbA-treated macrophages. Electron microscopy revealed an increase in the number and size of mitochondria. In 25 random microphotographs of cytoplasm, we detected 51 mitochondria in control, 79 in HbA treated and, 96 in HbS treated macrophages. The mitochondria volume and cristae size were significantly increased in macrophages treated with HbS. There was no increase in mtROS production in HbS treatment compared to ctrl. As expected, HbA treatment reduced mtROS production. The mitochondrial gene set (242 genes) was the second most enriched GSEA set in HbS-treated compared to HbA-treated macrophages. The larger mitochondrial size may be associated with a reduction of fission or an increase in fusion. We did not find differences in the expression of mitochondrial fission and fusion genes between HbS and HbA-treated macrophages. The increase in the mitochondrial size and cristae size may also be associated with increased oxidative phosphorylation. We found significant enrichment of genes responsible for oxidative phosphorylation in the HbS-treated macrophages. We did not find significant differences in the expression of glycolysis genes. CONCLUSION: Treatment of human macrophages with HbS significantly increases the number and volume of mitochondria, size of the cristae, and oxidative phosphorylation without upregulation of mtROS production and reduction of glycolysis. This work was supported by NIH Research Grants SC1HL150685, P50HL118006, and R01HL125005. We thank Drs. Castle Raley and Keith Crandall, George Washington University SPH Genomics Core, for sequencing and guidance in data analysis; Dr. Christine Brantner, GW Nanofabrication and Imaging Center, for TEM imaging. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Monocyte to macrophage differentiation and changes in cellular redox homeostasis promote cell type-specific HIV latency reactivation

HIV latency regulation in monocytes and macrophages can vary according to signals directing differentiation, polarization, and function. To investigate these processes, we generated an HIV latency model in THP-1 monocytes and showed differential levels of HIV reactivation among clonal populations. Monocyte-to-macrophage differentiation of HIV-infected primary human CD14+ and THP-1 cells induced HIV reactivation and showed that virus production increased concomitant with macrophage differentiation. We applied the HIV-infected THP-1 monocyte-to-macrophage (MLat) model to assess the biological mechanisms regulating HIV latency dynamics during monocyte-to-macrophage differentiation. We pinpointed protein kinase C signaling pathway activation and Cyclin T1 upregulation as inherent differentiation mechanisms that regulate HIV latency reactivation. Macrophage polarization regulated latency, revealing proinflammatory M1 macrophages suppressed HIV reactivation while anti-inflammatory M2 macrophages promoted HIV reactivation. Because macrophages rely on reactive-oxygen species (ROS) to exert numerous cellular functions, we disrupted redox pathways and found that inhibitors of the thioredoxin (Trx) system acted as latency-promoting agents in T-cells and monocytes, but opposingly acted as latency-reversing agents in macrophages. We explored this mechanism with Auranofin, a clinical candidate for reducing HIV reservoirs, and demonstrated Trx reductase inhibition led to ROS induced NF-κB activity, which promoted HIV reactivation in macrophages, but not in T-cells and monocytes. Collectively, cell type-specific differences in HIV latency regulation could pose a barrier to HIV eradication strategies.

IL-12p40 deletion reduces M1 macrophage polarization and alleviates cardiac remodeling via regulating Th17 cells differentiation, but not γδT 17 cells, in TAC mice

BackgroundThe interleukin (IL) −12 p40 subunit is the common subunit of IL-12 and IL-23. It affects the immune inflammatory response, which may be closely related to cardiac remodeling. In this study, the regulatory effect of IL-12p40 knockout (KO) on cardiac remodeling was investigated, and the underlying mechanism was explored. Methods and resultsMice were subjected to transverse aortic constriction (TAC) to establish a model of cardiac remodeling. First, IL-12p40 was deleted to observe its effects on cardiac remodeling and cardiac inflammation, and the results showed that IL-12p40 deletion reduced both T helper 17 (Th17) and γδT17 cell differentiation, decreased proinflammatory macrophage differentiation, alleviated cardiac remodeling, and relieved cardiac dysfunction in TAC mice. Next, we explored whether IL-17 regulated TAC-induced cardiac remodeling, and the results showed that IL-17 neutralization alleviated proinflammatory macrophage differentiation and cardiac remodeling in IL-12p40 knockout mice and WT mice. Neutralization with cluster of differentiation 4 receptor (CD4) and γδ T-cell receptor (γδTCR) antibodies inhibited pro-inflammatory macrophage polarization and improved cardiac remodeling, and CD4 neutralizing antibody (NAb) had more significant effects. Finally, adoptive transfer of Th17 cells aggravated proinflammatory macrophage differentiation and cardiac remodeling in TAC-treated CD4 KO mice, while neutralization with the IL-12p40 antibody alleviated these pathological changes. ConclusionMainly Th17 cells but not γδT17 cells secrete IL-17, which mediates IL-12p40, promotes the polarization of proinflammatory macrophages, and exacerbates cardiac remodeling in TAC mice. IL-12p40 may be a potential target for the prevention and treatment of cardiac remodeling.

CD226 promotes renal fibrosis by regulating macrophage activation and migration.

It has been found that CD226 plays an important role in regulating macrophage function, but its expression and function in macrophages during renal fibrogenesis have not been studied. Our data demonstrated that CD226 expression in macrophages was obviously upregulated in the unilateral ureteral obstruction model, while CD226 deficiency attenuated collagen deposition in renal interstitium along with fewer M1 within renal cortex and renal medulla and a lower level of proinflammatory factors compared to that of control littermates. Further studies demonstrated that Cd226-/- bone marrow-derived macrophages transferring could significantly reduce the tubular injury, collagen deposition, and proinflammatory cytokine secretion compared with that of Cd226+/+ bone marrow-derived macrophages transferring in the unilateral ureteral obstruction model. Mechanistic investigations revealed that CD226 promoted proinflammatory M1 macrophage accumulation in the kidney via suppressing KLF4 expression in macrophages. Therefore, our results uncovered a pathogenic role of CD226 during the development of chronic kidney disease by promoting monocyte infiltration from peripheral blood into the kidney and enhancing macrophage activation toward the inflammatory phenotype by suppressing KLF4 expression.

Galectin-3 absence alters lymphocytes populations dynamics behavior and promotes functional recovery after spinal cord injury in mice

Spinal cord injury (SCI) results from various mechanisms that damage the nervous tissue and the blood-brain barrier, leading to sensory and motor function loss below the injury site. Unfortunately, current therapeutic approaches for SCI have limited efficacy in improving patients outcomes. Galectin-3, a protein whose expression increases after SCI, influences the neuroinflammatory response by favoring pro-inflammatory M1 macrophages and microglia, while inhibiting pro-regenerative M2 macrophages and microglia, which are crucial for inflammation resolution and tissue regeneration. Previous studies with Galectin-3 knock-out mice demonstrated enhanced motor recovery after SCI. The M1/M2 balance is strongly influenced by the predominant lymphocytic profiles (Th1, Th2, T Reg, Th17) and cytokines and chemokines released at the lesion site. The present study aimed to investigate how the absence of galectin-3 impacts the adaptive immune system cell population dynamics in various lymphoid spaces following a low thoracic spinal cord compression injury (T9-T10) using a 30 g vascular clip for one minute. It also aimed to assess its influence on the functional outcome in wild-type (WT)and Galectin-3 knock-out (GALNEG) mice. Histological analysis with hematoxylin-eosin and Luxol Fast Blue staining revealed that WT and GALNEG animals exhibit similar spinal cord morphology. The absence of galectin-3 does not affect the common neuroanatomy shared between the groups prompting us to analyze outcomes between both groups. Following our crush model, both groups lost motor and sensory functions below the lesion level. During a 42-day period, GALNEG mice demonstrated superior locomotor recovery in the Basso Mouse Scale (BMS) gait analysis and enhanced motor coordination performance in the ladder rung walk test (LRW) compared to WT mice. GALNEG mice also exhibited better sensory recovery, and their electrophysiological parameters suggested a higher number of functional axons with faster nerve conduction. Seven days after injury, flow cytometry of thymus, spleen, and blood revealed an increased number of T Reg and Th2 cells, accompanied by a decrease in Th1 and Th17 cells in GALNEG mice. Immunohistochemistry conducted on the same day exhibited an increased number of Th2 and T Reg cells around the GALNEG's spinal cord lesion site. At 42-day dpi immunohistochemistry analyses displayed reduced astrogliosis and greater axon preservation in GALNEG's spinal cord seem as a reduction of GFAP immunostaining and an increase in NFH immunostaining, respectively. In conclusion, GALNEG mice exhibited better functional recovery attributed to the milder pro-inflammatory influence, compensated by a higher quantity of T Reg and Th2 cells. These findings suggest that galectin-3 plays a crucial role in the immune response after spinal cord injury and could be a potential target for clinical therapeutic interventions.

Deciphering the role of CX3CL1-CX3CR1 in aortic aneurysm pathogenesis: insights from Mendelian randomization and transcriptomic analyses.

The crucial role of inflammation in aortic aneurysm (AA) is gaining prominence, while there is still a lack of key cytokines or targets for effective clinical translation. Mendelian randomization (MR) analysis was performed to identify the causal relationship between 91 circulating inflammatory proteins and AA and between 731 immune traits and AA. Bulk RNA sequencing data was utilized to demonstrate the expression profile of the paired ligand-receptor. Gene enrichment analysis, Immune infiltration, and correlation analysis were employed to deduce the potential role of CX3CR1. We used single-cell RNA sequencing data to pinpoint the localization of CX3CL1 and CX3CR1, which was further validated by multiplex immunofluorescence staining. Cellchat analysis was utilized to infer the CX3C signaling pathway. Trajectory analysis and the Cytosig database were exploited to determine the downstream effect of CX3CL1-CX3CR1. We identified 4 candidates (FGF5, CX3CL1, IL20RA, and SCF) in multiple two-sample MR analyses. Subsequent analysis of the expression profile of the paired receptor revealed the significant upregulation of CX3CR1 in AA and its positive correlation with pro-inflammatory macrophages. Two sample MR between immune cell traits and AA demonstrated the potential causality between intermediate monocytes and AA. We finally deciphered in single-cell sequencing data that CX3CL1 sent by endothelial cells (ECs) acted on CX3CR1 of intermediated monocytes, leading to its recruitment and pro-inflammatory responses. Our study presented a genetic insight into the pathogenetic role of CX3CL1-CX3CR1 in AA, and further deciphered the CX3C signaling pathway between ECs and intermediate monocytes.

Lactobacillus Reuteri Vesicles Regulate Mitochondrial Function of Macrophages to Promote Mucosal and Cutaneous Wound Healing.

The interplay between bacteria and their host influences the homeostasis of the human immune microenvironment, and this reciprocal interaction also affects the process of tissue damage repair. A variety of immunomodulatory commensal bacteria reside in the body, capable of delivering membrane vesicles (MVs) to host cells to regulate the local immune microenvironment. This research revealed, for the initial time, the significant enhancement of mucosal and cutaneous wound healing by MVs secreted by the human commensal Lactobacillus reuteri (RMVs) through modulation of the inflammatory environment in wound tissue. Local administration of RMVs reduces the proportion of pro-inflammatory macrophages in inflamed tissues and mitigates the level of local inflammation, thereby facilitating the healing of oral mucosa and cutaneous wounds. The elevated oxidative stress levels in activated pro-inflammatory macrophages can be modulated by RMVs, resulting in phenotypic transformation of macrophages. Furthermore, 3-hydroxypropionaldehyde present in RMVs can decrease the mitochondrial permeability of macrophages and stabilize the mitochondrial membrane potential, thereby promoting the conversion of macrophages to an anti-inflammatory phenotype. This study pioneers the significance of commensal bacterial MVs in tissue injury repair and presents a novel concept for the repair of tissue damage.

Shift from Pro- to Anti-Inflammatory Phase in Pelvic Floor Muscles at Postpartum Matches Histological Signs of Regeneration in Multiparous Rabbits.

Background and Objectives: Pelvic floor muscles (PFM) play a core role in defecation and micturition. Weakening of PFM underlies urogynecological disorders such as pelvic organ prolapse and stress urinary incontinence. Vaginal delivery damages PFM. Muscle trauma implies an inflammatory response mediated by myeloid cells, essential for subsequent recovery. Molecular signaling characterizing the pro-inflammatory phase shifts M1 macrophages to M2 macrophages, which modulate muscle repair. The present study aimed to evaluate histological characteristics and the presence of M1 and M2 macrophages in bulbospongiosus (Bsm) and pubococcygeus muscles (Pcm). Materials and Methods: Muscles from young nulliparous (N) and multiparous rabbits on postpartum days three (M3) and twenty (M20) were excised and histologically processed to measure the myofiber cross-sectional area (CSA) and count the centralized myonuclei in hematoxylin-eosinstained sections. Using immunohistochemistry, M1 and M2 macrophages were estimated in muscle sections. Kruskal-Wallis or one-way ANOVA testing, followed by post hoc tests, were conducted to identify significant differences (p < 0.05). Results: The myofiber CSA of both the Bsm and Pcm of the M3 group were more extensive than those of the N and M20 groups. Centralized myonuclei estimated in sections from both muscles of M20 rabbits were higher than those of N rabbits. Such histological outcomes matched significant increases in HLA-DR immunostaining in M3 rabbits with the CD206 immunostaining in muscle sections from M20 rabbits. Conclusions: A shift from the pro- to anti-inflammatory phase in the bulbospongiosus and pubococcygeus muscles of multiparous rabbits matches with centralized myonuclei, suggesting the ongoing regeneration of muscles.

Left Ventricular Remodelling Associated with the Transient Elevated [68Ga]Ga-Pentixafor Activity in the Remote Myocardium Following Acute Myocardial Infarction.

Previous studies have initially reported accompanying elevated 2-deoxy-2[18F]fluoro-D-glucose ([18F]F-FDG) inflammatory activity in the remote area and its prognostic value after acute myocardial infarction (AMI). Non-invasive characterization of the accompanying inflammation in the remote myocardium may be of potency in guiding future targeted theranostics. [68Ga]Ga-Pentixafor targeting chemokine receptor 4 (CXCR4) on the surface of inflammatory cells is currently one of the promising inflammatory imaging agents. In this study, we sought to focus on the longitudinal evolution of [68Ga]Ga-Pentixafor activities in the remote myocardium following AMI and its association with cardiac function. Twelve AMI rats and six Sham rats serially underwent [68Ga]Ga-Pentixafor imaging at pre-operation, and 5, 7, 14 days post-operation. Maximum and mean standard uptake value (SUV) and target-to-background ratio (TBR) were assessed to indicate the uptake intensity. Gated [18F]F-FDG imaging and immunofluorescent staining were performed to obtain cardiac function and responses of pro-inflammatory and reparative macrophages, respectively. The uptake of [68Ga]Ga-Pentixafor in the infarcted myocardium peaked at day 5 (all P = 0.003), retained at day 7 (all P = 0.011), and recovered at day 14 after AMI (P > 0.05), paralleling with the rise-fall pro-inflammatory M1 macrophages (P < 0.05). Correlated with the peak activity in the infarct territory, [68Ga]Ga-Pentixafor uptake in the remote myocardium on day 5 early after AMI significantly increased (AMI vs. Sham: SUVmean, SUVmax, and TBRmean: all P < 0.05), and strongly correlated with contemporaneous EDV and/or ESV (SUVmean and TBRmean: both P < 0.05). The transitory remote activity recovered as of day 7 post-AMI (AMI vs. Sham: P > 0.05). Corresponding with the peaked [68Ga]Ga-Pentixafor activity in the infarcted myocardium, the activity in the remote region elevated accordingly and led to contemporaneous left ventricular remodelling early after AMI. Further studies are warranted to clarify its clinical application potential.

595 Unremitting Pro-inflammatory Cell Phenotypes and Macrophage Activity, Following Paediatric Burn Injury

595 Unremitting Pro-inflammatory Cell Phenotypes and Macrophage Activity, Following Paediatric Burn Injury

MIF/NR3C2 axis regulates glucose metabolism reprogramming in pancreatic cancer through MAPK-ERK and AP-1 pathways.

Inflammation and aberrant cellular metabolism are widely recognized as hallmarks of cancer. In pancreatic ductal adenocarcinoma (PDAC), inflammatory signaling and metabolic reprogramming are tightly interwoven, playing pivotal roles in the pathogenesis and progression of the disease. However, the regulatory functions of inflammatory mediators in metabolic reprogramming in pancreatic cancer have not been fully explored. Earlier, we demonstrated that pro-inflammatory mediator macrophage migration inhibitory factor (MIF) enhances disease progression by inhibiting its downstream transcriptional factor nuclear receptor subfamily 3 group C member 2 (NR3C2). Here, we provide evidence that MIF and NR3C2 interactively regulate metabolic reprogramming, resulting in MIF-induced cancer growth and progression in PDAC. MIF positively correlates with the HK1 (hexokinase 1), HK2 (hexokinase 2) and LDHA (lactate dehydrogenase) expression and increased pyruvate and lactate production in PDAC patients. Additionally, MIF augments glucose uptake and lactate efflux by upregulating HK1, HK2 and LDHA expression in pancreatic cancer cells in vitro and in mouse models of PDAC. Conversely, a reduction in HK1, HK2 and LDHA expression is observed in tumors with high NR3C2 expression in PDAC patients. NR3C2 suppresses HK1, HK2 and LDHA expression, thereby inhibiting glucose uptake and lactate efflux in pancreatic cancer. Mechanistically, MIF-mediated regulation of glycolytic metabolism involves the activation of the mitogen-activated protein kinase-ERK signaling pathway, whereas NR3C2 interacts with the activator protein 1 to regulate glycolysis. Our findings reveal an interactive role of the MIF/NR3C2 axis in regulating glucose metabolism supporting tumor growth and progression and may be a potential target for designing novel approaches for improving disease outcome.

Targeting foamy macrophages by manipulating ABCA1 expression to facilitate lesion healing in the injured spinal cord

Spinal cord injury (SCI) triggers a complex cascade of events, including myelin loss, neuronal damage, neuroinflammation, and the accumulation of damaged cells and debris at the injury site. Infiltrating bone marrow derived macrophages (BMDMϕ) migrate to the epicenter of the SCI lesion, where they engulf cell debris including abundant myelin debris to become pro-inflammatory foamy macrophages (foamy Mϕ), participate neuroinflammation, and facilitate the progression of SCI. This study aimed to elucidate the cellular and molecular mechanisms underlying the functional changes in foamy Mϕ and their potential implications for SCI. Contusion at T10 level of the spinal cord was induced using a New York University (NYU) impactor (5 g rod from a height of 6.25 mm) in male mice. ABCA1, an ATP-binding cassette transporter expressed by Mϕ, plays a crucial role in lipid efflux from foamy cells. We observed that foamy Mϕ lacking ABCA1 exhibited increased lipid accumulation and a higher presence of lipid-accumulated foamy Mϕ as well as elevated pro-inflammatory response in vitro and in injured spinal cord. We also found that both genetic and pharmacological enhancement of ABCA1 expression accelerated lipid efflux from foamy Mϕ, reduced lipid accumulation and inhibited the pro-inflammatory response of foamy Mϕ, and accelerated clearance of cell debris and necrotic cells, which resulted in functional recovery. Our study highlights the importance of understanding the pathologic role of foamy Mϕ in SCI progression and the potential of ABCA1 as a therapeutic target for modulating the inflammatory response, promoting lipid metabolism, and facilitating functional recovery in SCI.

ASYMPTOTIC STABILITY FOR A FREE BOUNDARY MODEL OF AN ATHEROSCLEROTIC PLAQUE FORMATION IN THE PRESENCE OF REVERSE CHOLESTEROL TRANSPORT WITH HOLLING TYPE-III FUNCTIONAL RESPONSE

Atherosclerosis, as a chronic inflammatory disease, has been a threat to human health. How to diagnose and prevent this disease has long been the focus of medical and biomathematics study. In this paper, we investigate a free boundary model of an atherosclerotic plaque formation in the presence of reverse cholesterol transport, which includes low-density lipoprotein, high-density lipoprotein, endothelial stimulating cytokines, pro-inflammatory and anti-inflammatory macrophages, as well as foam cells. For this model, we use the Holling type-III response function instead of the usual Holling type-II to describe the change of the concentration of each substance. We first introduce the auxiliary function [Formula: see text] to prove the existence and uniqueness of small radially symmetric stationary plaque for appropriate [Formula: see text] and [Formula: see text] by using the contraction mapping principle and maximum principle, and then establish a condition to ensure their asymptotic stability behavior by expanding the corresponding steady-state solution.

Metabolic rewiring promotes anti-inflammatory effects of glucocorticoids.

Glucocorticoids represent the mainstay of therapy for a broad spectrum of immune-mediated inflammatory diseases. However, the molecular mechanisms underlying their anti-inflammatory mode of action have remained incompletely understood1. Here we show that the anti-inflammatory properties of glucocorticoids involve reprogramming of the mitochondrial metabolism of macrophages, resulting in increased and sustained production of the anti-inflammatory metabolite itaconate and consequent inhibition of the inflammatory response. The glucocorticoid receptor interacts with parts of the pyruvate dehydrogenase complex whereby glucocorticoids provoke an increase in activity and enable an accelerated and paradoxical flux of the tricarboxylic acid (TCA) cycle in otherwise pro-inflammatory macrophages. This glucocorticoid-mediated rewiring of mitochondrial metabolism potentiates TCA-cycle-dependent production of itaconate throughout the inflammatory response, thereby interfering with the production of pro-inflammatory cytokines. By contrast, artificial blocking of the TCA cycle or genetic deficiency in aconitate decarboxylase 1, the rate-limiting enzyme of itaconate synthesis, interferes with the anti-inflammatory effects of glucocorticoids and, accordingly, abrogates their beneficial effects during a diverse range of preclinical models of immune-mediated inflammatory diseases. Our findings provide important insights into the anti-inflammatory properties of glucocorticoids and have substantial implications for the design of new classes of anti-inflammatory drugs.

Macrophage polarization: an important role in inflammatory diseases.

Macrophages are crucial cells in the human body's innate immunity and are engaged in a variety of non-inflammatory reactions. Macrophages can develop into two kinds when stimulated by distinct internal environments: pro-inflammatory M1-like macrophages and anti-inflammatory M2-type macrophages. During inflammation, the two kinds of macrophages are activated alternatively, and maintaining a reasonably steady ratio is critical for maintaining homeostasis in vivo. M1 macrophages can induce inflammation, but M2 macrophages suppress it. The imbalance between the two kinds of macrophages will have a significant impact on the illness process. As a result, there are an increasing number of research being conducted on relieving or curing illnesses by altering the amount of macrophages. This review summarizes the role of macrophage polarization in various inflammatory diseases, including autoimmune diseases (RA, EAE, MS, AIH, IBD, CD), allergic diseases (allergic rhinitis, allergic dermatitis, allergic asthma), atherosclerosis, obesity and type 2 diabetes, metabolic homeostasis, and the compounds or drugs that have been discovered or applied to the treatment of these diseases by targeting macrophage polarization.