Macrophage Accumulation Research Articles

CD163+ Macrophages Induce Endothelial-to-Mesenchymal Transition in Atheroma.

Cell phenotype switching is increasingly being recognized in atherosclerosis. However, our understanding of the exact stimuli for such cellular transformations and their significance for human atherosclerosis is still evolving. Intraplaque hemorrhage is thought to be a major contributor to plaque progression in part by stimulating the influx of CD163+ macrophages. Here, we explored the hypothesis that CD163+ macrophages cause plaque progression through the induction of proapoptotic endothelial-to-mesenchymal transition (EndMT) within the fibrous cap. Human coronary artery sections from CVPath's autopsy registry were selected for pathological analysis. Athero-prone ApoE-/- and ApoE-/-/CD163-/- mice were used for in vivo studies. Human peripheral blood mononuclear cell-induced macrophages and human aortic endothelial cells were used for in vitro experiments. In 107 lesions with acute coronary plaque rupture, 55% had pathological evidence of intraplaque hemorrhage in nonculprit vessels/lesions. Thinner fibrous cap, greater CD163+ macrophage accumulation, and a larger number of CD31/FSP-1 (fibroblast specific protein-1) double-positive cells and TUNEL (terminal deoxynucleotidyl transferase-dUTP nick end labeling) positive cells in the fibrous cap were observed in nonculprit intraplaque hemorrhage lesions, as well as in culprit rupture sections versus nonculprit fibroatheroma sections. Human aortic endothelial cells cultured with supernatants from hemoglobin/haptoglobin-exposed macrophages showed that increased mesenchymal marker proteins (transgelin and FSP-1) while endothelial markers (VE-cadherin and CD31) were reduced, suggesting EndMT induction. Activation of NF-κB (nuclear factor kappa β) signaling by proinflammatory cytokines released from CD163+ macrophages directly regulated the expression of Snail, a critical transcription factor during EndMT induction. Western blot analysis for cleaved caspase-3 and microarray analysis of human aortic endothelial cells indicated that apoptosis was stimulated during CD163+ macrophage-induced EndMT. Additionally, CD163 deletion in athero-prone mice suggested that CD163 is required for EndMT and plaque progression. Using single-cell RNA sequencing from human carotid endarterectomy lesions, a population of EndMT was detected, which demonstrated significant upregulation of apoptosis-related genes. CD163+ macrophages provoke EndMT, which may promote plaque progression through fibrous cap thinning.

An injectable and antifouling hydrogel prevents the development of abdominal adhesions by inhibiting the CCL2/CCR2 interaction

Abdominal adhesion, a serious complication of abdominal surgery, often resists mitigation by current drug administration and physical barriers. To address this issue, we developed an injectable, antifouling hydrogel through the free-radical polymerization of methacrylate chondroitin sulfate (CS-GMA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) monomers, dubbed the CGM hydrogel. We systematically analyzed its physicochemical properties, including rheological strength, biocompatibility, and antifouling capabilities. A rat abdominal cecum adhesion model was constructed to assess the effectiveness of CGM hydrogel in preventing postoperative adhesion and recurrent adhesion. In addition, multi-omics analyses identified the relationship between adhesion development and CCL2/CCR2 interaction. Notably, CGM hydrogel can thwart the recruitment and aggregation of fibroblasts and macrophages by inhibiting the CCL2/CCR2 interaction. Moreover, CGM hydrogel significantly dampens the activity of fibrosis-linked cytokines (TGF-βR1) and recalibrates extracellular matrix deposition-related cytokines (t-PA and PAI-1, Col Ⅰ and MMP-9). Cumulatively, the dual action of CGM hydrogel-as a physical barrier and cytokine regulator-highlights its promising potential in clinical application for abdominal adhesion prevention.

A Systematic Review and Meta-Analysis on the Role of Bempedoic Acid in Cardiovascular Outcomes for Patients With Statin Intolerance.

Atherosclerosis, a multifaceted pathogenic process affecting the arteries and aorta, poses a significant threat because of its potential to impede or entirely obstruct blood flow by narrowing blood vessels. This intricate progression involves various factors such as dyslipidemia, immunological responses, inflammation, and endothelial dysfunction. The initial phase manifests as the formation of fatty streaks, considered a pivotal hallmark in the inception of atherosclerotic plaques, a process that can commence as early as childhood. Over time, this process evolves, characterized by the thickening of the arterial inner layer (intima) and accumulation of lipid-laden macrophages, commonly known as foam cells, along with the buildup of the extracellular matrix. Subsequent stages witness the proliferation and aggregation of smooth muscle cells, culminating in the formation of atheroma plaques. As these lesions progress, apoptosis can occur in the deeper layers, further recruiting macrophages, which may undergo calcification and transform into atherosclerotic plaques. Notably, mechanisms such as arterial remodeling and intraplaque hemorrhage also contribute significantly to the progression of atherosclerotic cardiovascular disease, although these facets fall beyond the scope of this article. This study aimed to systematically review and conduct a meta-analysis of randomized controlled trials investigating the efficacy and safety of bempedoic acid in statin-intolerant patients with hyperlipidemia and to provide conclusions and recommendations accordingly. A systematic search of databases, such as PubMed, Web of Science, and Embase, will be performed. Only randomized trials will be included comparing bempedoic acid with placebo in statin-intolerant patients. This study aimed to provide a comprehensive understanding of the role of bempedoic acid in managing hyperlipidemia in statin-intolerant patients. In primary prevention, for patients unable to tolerate recommended statins, bempedoic acid was associated with a significant reduction in major adverse cardiovascular events (MACE) as the primary endpoint.

AN0025 in combination with definitive chemoradiotherapy (dCRT) in unresectable locally advanced or locally recurrent esophageal cancer (EC): A single-arm, open-label, multicenter, phase Ib study.

e16076 Background: AN0025 is a selective EP4 inhibitor that demonstrates antitumor activity by modulating the accumulation and function of macrophages and immunosuppressive myeloid cells in tumor microenvironment. The combination of AN0025 with CRT as neoadjuvant therapy has shown synergistic antitumor efficacy in locally advanced rectal cancer in a prior clinical trial (NCT03152370). Methods: This Phase Ib study includes a dose escalation phase followed by an expansion phase to evaluate the safety, tolerability, and feasibility of AN0025 plus dCRT for unresectable locally advanced or locally recurrent EC or esophagogastric junction cancer. Antitumor efficacy was assessed per RECIST v1.1. The eligible patients (pts) are candidates for dCRT, who received RT (2.0 Gy/fraction, totally 50-60 Gy) with concurrent weekly paclitaxel and carboplatin for 4 weeks, followed by two doses of consolidation chemotherapy on Week 8 and Week 12. AN0025 (250 mg or 500 mg QD) was administered orally for 15 weeks concurrently with dCRT. At the beginning of Week 17, pts would start AN0025 monotherapy in the maintenance phase. Results: As of Jan 12, 2024, 12 pts (11 males and 1 female, median age 62) with histologically confirmed esophageal squamous cell carcinoma (ESCC) were enrolled and received the study treatment, 5 at the 250 mg dose level and 7 at the 500 mg dose level. Among those 12 pts, 11 were locally advanced ESCCs and 1 was locally recurrent ESCC. The most common AN0025-related adverse events (AEs) were weight decreased (33%), anemia (33%), and white blood cell count decreased (25%). Two pts (17%) experienced Grade ≥3 AN0025-related AEs (one Grade 3 weight decreased and one Grade 3 esophageal fistula). No dose-limiting toxicity occurred at either dose level, and the maximum tolerated dose was not reached. The median follow-up was 14.2 months, with 8 pts remaining on study treatment and a maximum time on treatment of 2 years. The disease control rate (DCR) was 92% (11/12). The median progression-free survival (PFS) was not reached, with 6-month and 1-year PFS rates of 91% and 73%, respectively. The 1-year overall survival (OS) rate was 82%. Additionally, among the 8 pts with measurable lesion(s) at baseline, 1 (13%) achieved confirmed complete response (CR), and 6 achieved partial response (PR), including 5 confirmed PRs, giving an unconfirmed overall response rate (ORR) of 88% (7/8) and a confirmed ORR of 75% (6/8). AN0025 PK approached linearity at both 250 mg and 500 mg QD. AN0025 PK in combination with dCRT showed no interactions. Conclusions: This Phase Ib study suggests that AN0025 plus dCRT exhibits favorable safety and encouraging preliminary efficacy in unresectable locally advanced or locally recurrent EC, warranting further investigation. Clinical trial information: NCT05191667 .

Molecular mechanism of renal lipid accumulation in diabetic kidney disease.

Diabetic kidney disease (DKD) is a leading cause of end stage renal disease with unmet clinical demands for treatment. Lipids are essential for cell survival; however, renal cells have limited capability to metabolize overloaded lipids. Dyslipidaemia is common in DKD patients and renal ectopic lipid accumulation is associated with disease progression. Unveiling the molecular mechanism involved in renal lipid regulation is crucial for exploring potential therapeutic targets. In this review, we focused on the mechanism underlying cholesterol, oxysterol and fatty acid metabolism disorder in the context of DKD. Specific regulators of lipid accumulation in different kidney compartment and TREM2 macrophages, a lipid-related macrophages in DKD, were discussed. The role of sodium-glucose transporter 2 inhibitors in improving renal lipid accumulation was summarized.

Trem2 drives accumulation of pro-fibrotic monocyte-derived macrophages in the infarcted myocardium

Trem2 drives accumulation of pro-fibrotic monocyte-derived macrophages in the infarcted myocardium

Choroid plexus CCL2‒CCR2 signaling orchestrates macrophage recruitment and cerebrospinal fluid hypersecretion in hydrocephalus

The choroid plexus (ChP) serves as the principal origin of cerebrospinal fluid (CSF). CSF hypersecretion due to ChP inflammation has emerged as an important pathogenesis of hydrocephalus recently. Nevertheless, the precise mechanisms of ChP inflammation and the ensuing CSF hypersecretion in hydrocephalus remain ill-defined. In the present study, we elucidate the critical role of macrophages in the pathogenesis of ChP inflammation. Specifically, we identify the chemokine CCL2, released by ChP epithelial cells, recruits CCR2+ monocytes to the ChP thereby inciting hydrocephalus pathogenesis. The accumulated ChP macrophages increase the inflammation in ChP epithelial cells through TNF-α/TNFR1/NF-κB signaling cascade, thereby leading to CSF hypersecretion. Strikingly, augmentation of ChP‒CCL2 using an adeno-associated viral approach (AAV) exacerbates macrophage recruitment, activation, and ventriculomegaly in rat PHH models. Systemic application of Bindarit, a specific CCL2 inhibitor, significantly inhibits ChP macrophage infiltration and activation and reduces CSF secretion rate. Furthermore, the administration of CCR2 antagonist (INCB 3284) reduces ChP macrophage accumulation and ventriculomegaly. This study not only unveils the ChP CCL2‒CCR2 signaling in the pathophysiology of hydrocephalus but also unveils Bindarit as a promising therapeutic choice for the management of posthemorrhagic hydrocephalus.

LY86 facilitates ox-LDL-induced lipid accumulation in macrophages by upregulating SREBP2/HMGCR expression

LY86, also known as MD1, has been implicated in various pathophysiological processes including inflammation, obesity, insulin resistance, and immunoregulation. However, the role of LY86 in cholesterol metabolism remains incompletely understood. Several studies have reported significant up-regulation of LY86 mRNA in atherosclerosis; nevertheless, the regulatory mechanism by which LY86 is involved in this disease remains unclear. In this study, we aimed to investigate whether LY86 affects ox-LDL-induced lipid accumulation in macrophages. Firstly, we confirmed that LY86 is indeed involved in the process of atherosclerosis and found high expression levels of LY86 in human atherosclerotic plaque tissue. Furthermore, our findings suggest that LY86 may mediate intracellular lipid accumulation induced by ox-LDL through the SREBP2/HMGCR pathway. This mechanism could be associated with increased cholesterol synthesis resulting from enhanced endoplasmic reticulum stress response.

Definitive chemoradiotherapy induces T-cell-inflamed tumor microenvironment in unresectable locally advanced esophageal squamous cell carcinoma.

Chemoradiotherapy (CRT) modulates the tumor immune microenvironment of multiple cancer types, including esophageal cancer, which potentially induces both immunogenicity and immunosuppression by upregulating the presentation of tumor-specific antigens and immune checkpoint molecules in tumors, respectively. The prognostic effects of immune modification by CRT in esophageal squamous cell carcinoma (ESCC) remain controversial because of the lack of detailed immunological analyses using paired clinical specimens before and after CRT. We aimed to clarify the immunological changes in the tumor microenvironment caused by CRT and elucidate the predictive importance of clinical response and prognosis and the rationale for the necessity of subsequent programmed cell death protein 1 (PD-1) inhibitor treatment. In this study, we performed a comprehensive immunological analysis of paired biopsy specimens using multiplex immunohistochemistry before and after CRT in patients with unresectable locally advanced ESCC. CRT significantly increased the intra-tumoral infiltration and PD-1 expression of CD8+ T cells and conventional CD4+ T cells but decreased those of regulatory T cells and the accumulation of tumor-associated macrophages. Multivariate analysis of tumor-infiltrating T-cell phenotypes revealed that the density of PD-1+CD8+ T cells in the tumor after CRT could predict a confirmed complete response and favorable survival. This study showed that CRT improved the immunological characteristics of unresectable locally advanced ESCC and identified the density of PD-1+CD8+ T cells as a predictive factor for prognosis. This finding supports the rationale for the necessity of subsequent PD-1 inhibitor treatment.

Pathological Effects of Aflatoxin on Hepatic Tissue of Rats, Experimental Study

The objective of studying this research is to discuss the pathological influence of aflatoxin on hepatic tissue. Aflatoxin was produced in this work using Aspergillus flavus. The samples were mixed with Potato Dextrose Agar (PDA) and left to incubate at a temperature of 28 ± 2°C for three to five days. We employed the fungal species for further usage once they were incubated. The AF was made via a fermentation process with Aspergillus parasitcus and rice, After the rice had fermented properly, it was steams to destroy the fungus, dried, and pulverised into a powder. The AF concentration in rice residue was determined using a TLC fluorometric densitometer on TLC spots. Ten rats from each of the two experimental groups—"G1 Control" (fed a baseline diet without AF) and "AF" (fed a different diet)—were randomly assigned to participate in the study. Group 2 rats were given 25 μg of AF daily. This study's duration was ninety days. Then, blood specimens were drawn by heart puncture using a syringe to determine serum enzyme levels. The animals were sacrificed in order to get tissue samples as well enzyme levels were assessed in serum specimens that had been centrifuged at 4000 × g for 15 minutes at 4 °C. The levels of AST, ALT, and GGT were determined using a spectrophotometer and a kit that was received from Biolabo. Liver samples were collected from rats after scarification, embedded in paraffin wax, and fixed with 10% neutralised formaldehyde. Hematoxylin and eosin were used for staining. The AF-treated group had substantially high levels of those enzymes compare to the control group (p < 0.05). G2 demonstrated that macrophage aggregations in the liver parenchyma constitute granulomatous lesions. Another portion showed hepatocyte apoptosis, which is defined by dense nuclei in the hepatocyte's irregular esonophilic cytoplasm, and a necrotic region with pyknosis or no nuclei at all. A portion of the liver of rats that were treated with aflatoxin showed proliferation of kupffer cells together with a few clusters of mononuclear cells around the major vein. In conclusion, Aflatoxin can affect of liver tissue histology as well as liver enzymes such as ALT, AST as well as GGT.

ALTERAÇÕES HISTOPATOLÓGICAS NO SISTEMA RESPIRATÓRIO EM DECORRÊNCIA DO USO DE CIGARRO ELETRÔNICO

ABSTRACT - Introduction: The electronic cigarette was developed as an alternative to the conventional cigarette. Its mechanism of action involves the inhalation of numerous substances that are associated with a potential for cytotoxicity leading to histopathological changes in the respiratory system. Objective: To review scientific literature on histopathological changes in the respiratory system induced by EC substances. Methods: Literature review, with a search for articles in the PubMed, Scielo and Google Scholar databases between July and October 2023. The search was carried out with 19 articles from 2019 to 2023, using the descriptors: “histology”, “e-cigarettes” and “lung injuries”. Results: Vaping contains propylene glycol, vegetable glycerin, vitamin E acetate and nicotine, substances that causes damage to the respiratory system. Tissue studies in different histological stains showed: exposure to infiltration of inflammatory cells, aggregation of macrophages, granulomatous inflammation and significant hyperplasia of mucosal cells in groups that obtained the substance propylene glycol and vitamin E acetate. In relation to the cytological preparation of bronchoalveolar lavage, inflammatory cells were found leading to endogenous lipoid pneumonia. Other tests revealed a pattern of acute lung injury - diffuse alveolar damage and acute fibrinous and organizing pneumonia. Other research has noted that vitamin E acetate acts on surfactant, preventing it from maintaining the surface tension of the pulmonary alveoli. In the case of nicotine use, exposure to nicotine causes apoptosis and the release of inflammatory proteins, leading to the infiltration of inflammatory cells in the mucosa, submucosa and glandular tissue of the airways. Conclusion: The literature shows that the use of electronic cigarettes is harmless to the body. The changes reported range from hyperplasia of the respiratory epithelium, inflammatory changes, lipoid pneumonia, acute pneumonia and diffuse alveolar damage, among others. KEYWORDS – Histology. Electronic Cigarette. Respiratory System.

Cardiac sympathetic overdrive, M2 macrophage activation and fibroblast heterogeneity are associated with cardiac remodeling in a chronic pressure overload rat model of HFpEF.

Heart failure with preserved ejection fraction (HFpEF) is a multifaceted pathogenesis disease and the exact mechanisms driving HFpEF have not been completely elucidated. Pressure overload hypertrophy (POH) related fibroblasts and M2 macrophages in HFpEF myocardium have been recently identified and are now of great interest. Sympathetic overdrive has also been implicated in HFpEF. This study is designed to dynamically observe the potential roles of aforementioned mechanisms in pathological remodeling and cardiac dysfunction in chronic PO rats. Surgical constriction of the abdominal aorta was used for induction of HFpEF. Echocardiography, electrocardiogram, hemodynamic measurement, hematoxylin and eosin staining, Masson staining, immunohistochemistry and immunofluorescence were performed to assess the changes in heart dysfunction, cardiac remodeling and driving mechanisms at different time points (2, 18, 24weeks). The PO induced HFpEF model was well established, which was confirmed by the persistent increase in carotid artery systolic and diastolic blood pressure, and left ventricle hypertrophy at the corresponding postoperative stage. Meanwhile, PO hypertrophy gradually developed into HFpEF, associated with QT and QTc intervals prolongation, normal systolic (EF was maintained at >50%) but impaired diastolic function (increasing LVEDP and LV -dP/dtmin, abnormal E/A ratio), increased myocytes size, and observed relatively slight inflammatory infiltration but robust reactive fibrosis. IHC staining further confirmed that macrophages (CD68) but not neutrophils (MPO) or T cells (CD3) accounted for a predominant proportion of infiltrating cells. Mechanistically, we found that the infiltrating macrophages in the heart expressed high levels of CD206 which was simultaneously adjacent to POH fibroblasts appeared to overexpression of α-SMA in PO rats at late stages. Interestingly, we distinguished two different POHF sub-populations during PO induced HFpEF development, according to non overlapping signals of α-SMA and PDGFRα/β proteins. Additionally, PO led to a pronounced exaggeration in sympathetic fibers at all time points. These findings suggest that the establishing model here begins with cardiac sympathetic overdrive, subsequently along with immune cells especially M2 macrophage accumulation and fibroblast heterogeneity at later stages is associated with the development of cardiac maladaptive remodeling and diastolic dysfunction thus further progression to HFpEF.

Pharmacological Inhibition of MMP-12 Exerts Protective Effects on Angiotensin II-Induced Abdominal Aortic Aneurysms in Apolipoprotein E-Deficient Mice.

Human abdominal aortic aneurysms (AAAs) are characterized by increased activity of matrix metalloproteinases (MMP), including MMP-12, alongside macrophage accumulation and elastin degradation, in conjunction with superimposed atherosclerosis. Previous genetic ablation studies have proposed contradictory roles for MMP-12 in AAA development. In this study, we aimed to elucidate if pharmacological inhibition of MMP-12 activity with a phosphinic peptide inhibitor protects from AAA formation and progression in angiotensin (Ang) II-infused Apoe-/- mice. Complimentary studies were conducted in a human ex vivo model of early aneurysm development. Administration of an MMP-12 inhibitor (RXP470.1) protected hypercholesterolemia Apoe-/- mice from Ang II-induced AAA formation and rupture-related death, associated with diminished medial thinning and elastin fragmentation alongside increased collagen deposition. Proteomic analyses confirmed a beneficial effect of MMP-12 inhibition on extracellular matrix remodeling proteins combined with inflammatory pathways. Furthermore, RXP470.1 treatment of mice with pre-existing AAAs exerted beneficial effects as observed through suppressed aortic dilation and rupture, medial thinning, and elastin destruction. Our findings indicate that pharmacological inhibition of MMP-12 activity retards AAA progression and improves survival in mice providing proof-of-concept evidence to motivate translational work for MMP-12 inhibitor therapy in humans.

Role of miR-128-3p and miR-195-5p as biomarkers of coronary artery disease in Indians: a pilot study

Coronary artery disease (CAD) imposes a significant economic burden in developing countries like India. Timely diagnosis and treatment should be prioritized to mitigate the disease. Current diagnostic tools being invasive and less specific raise the need to develop less invasive and more reliable molecular biomarkers. MicroRNAs (miRNAs) are an emerging class of molecules that can serve as a potential source of non-invasive biomarkers for CAD. The objective of this study was to determine the potential of circulatory miRNAs as diagnostic biomarkers in CAD. In this study, we have reported two microRNAs, miR-128-3p and miR-195-5p in the serum of CAD patients in Indian Population. A total of 124 subjects were recruited which included 89 angiographically proven CAD patients and 35 control subjects. Our results show a significant decrease in the levels of miR-128-3p in CAD patients while there were no significant changes in the levels of miR-195-5p. Further bioinformatics analysis revealed the potential role of miR-128-3p in cholesterol homeostasis. Altered homeostasis due to cholesterol accumulation in macrophages is the driving force behind formation of foam cells which in turn accelerates the progression of CAD. Here, we have shown that miR-128-3p increases cholesterol levels in macrophages by decreasing cholesterol efflux in-vitro.

#1451 Calcimimetics reduce the progression of high-phosphate diet-induced tubular damage

Abstract Background and Aims During chronic kidney disease (CKD) progresses, there is an increased phosphate load and the concentration of the phosphaturic hormones PTH and FGF23 rises. In patients, phosphate and FGF23 are discussed as risk factors for CKD progression. We have recently shown that mice with high phosphate, PTH and FGF23 levels develop Stat3/Kim-1-mediated proximal tubule damage and tubulointerstitial fibrosis associated with increased MCP-1 expression and accumulation of macrophages. Calcimimetics lower PTH and FGF23 levels in hemodialysis patients and are thought to have both cardio- and nephroprotective effects. In a preclinical study, cinacalcet was shown to stabilize podocyte function in proteinuric mice. Therefore, we postulate that calcimimetics also have a positive effect on the progression of tubular damage in mice with high phosphate, PTH and FGF23 levels. Method For the induction of phosphaturic hormones with concomitant tubule damage, male C57BL/6 mice were fed a 2.0% high phosphate diet (HPD) and compared to animals on a 0.8% control phosphate diet (CPD). After four months, one HPD group was additionally treated with 1 mg/kg body weight/day etelcalcetide (KP-2326). Six months after the start of the trial, blood and urine samples as well as kidneys were taken for biochemical, histological and molecular biological examinations. Results KP-2326 treatment reduced HPD-induced PTH and FGF23 levels, but had no effect on increased phosphate excretion or elevated serum phosphate levels. Histologically, tubular damage was not as pronounced in the KP-2326-treated HPD animals as in the HPD group without therapy. The increased BUN levels caused by HPD and the albuminuria were significantly reduced by KP-2326. KP-2326 reduced HPD-mediated activation of Stat3 in proximal tubule cells and decreased Kim-1 synthesis at both mRNA and protein levels. Moreover, KP-2326 significantly reduced the mRNA expression of Ccl2 and the macrophage-specific marker Adgre1 compared to the untreated HPD group, which was histologically reflected in a lower accumulation of F4/80+ macrophages around the damaged tubules. Conclusion Treatment with KP-2326 was able to reduce the progression of HPD-induced tubule damage, at least in part due to the reduction in PTH and FGF23 levels.

#1449 Maturation of tertiary lymphoid structures in progressive kidney damage due to chronic phosphate load

Abstract Background and Aims We have recently shown that a high phosphate diet (HPD) in mice leads to an increase in FGF23 levels and causes progressive tubular damage and interstitial fibrosis with increased accumulation of macrophages and concomitant perivascular immune cell aggregates in the corticomedullary zone. Such tertiary lymphoid structures (TLS) can develop as a result of chronic inflammation and have already been described in lupus nephritis and IgA nephropathy, among others. In our model, the question arose to what extent damage to the proximal tubule is temporally associated with the development and maturation of TLS and which factors favor TLS development. Method Wild-type mice were fed HPD for 1, 2, 3, 4 and 6 months and the kidneys of each were compared with those of mice on a normal phosphate diet (NPD). To evaluate the effect of high FGF23 ± phosphate, Fgf23 was overexpressed in mice on NPD and HPD using an adeno-associated virus (AAV-Fgf23), and hypophosphatemic Hyp mice were used. Results An increased tubular damage score was seen after only two months of HPD. In parallel, perivascular immune cell clusters developed in the corticomedullary zone and in the renal cortex, which were characterized by aggregates of CD45R+ B cells and CD3+ T cells, as well as LYVE1+ lymphatic vessels after three months of HPD and were accompanied by increased expression of venous markers (Plvap, Aplnr, EphB4) and cell adhesion molecules (Sell, Vcam1, Madcam1). Further analyses showed a time-dependent induction of the immunofibroblast-derived chemokines Cxcl13 and Ccl19, as well as the lymphotoxins Lta and Ltb, which are important for the differentiation of immunofibroblasts into follicular dendritic cells (FDC) and follicular reticular cells (FRC). Already after four months of HPD, proliferating B-cell clusters with FDCs, FRCs located in T-cell clusters, podoplanin+ networks, high endothelial venules, plasma cells and increased IgD synthesis indicated fully mature TLS, while tubular damage and fibrosis continued to increase until six months of HPD. Compared to AAV-Fgf23 mice on NPD, only AAV-Fgf23 animals on HPD developed tubular damage with fibrosis and fully mature TLS. Hypophosphatemic Hyp mice with high FGF23 showed neither signs of tubular damage nor the development of TLS. Conclusion The development of renal TLS due to chronic high phosphate load coincides with the development of tubular damage, with earlier maturation of TLS and progression of tubular damage.

Pulmo-protection of long-term swimming exercise via improving insulin sensitivity in monocrotaline-induced pulmonary hypertensive rats

Exercise has been recognized as an effective intervention in the treatment of pulmonary arterial hypertension (PAH), supported by numerous studies. However, the precise effects of exercise on pulmonary function remain to be fully elucidated. In this study, using a rat model of swimming exercise training and monocrotaline-induced PAH, we aimed to explore its impact on pulmonary morphology and function. Our investigations revealed that MCT-treated rats exhibited augmented mean pulmonary arterial pressure (MPAP) and pulmonary vascular remodeling, which can be attenuated by 4 weeks of swimming exercise training (60 min/day, 5 days/week). Notably, MCT-treated rats showed impaired pulmonary function, as manifested by decreased tidal volume and dynamic compliance, which were reversed by exercise training. Assessment of pulmonary substrate in PAH rats indicated a prominent pro-inflammatory substrate, evidenced by macrophage accumulation through quantitative immunohistological analysis of macrophage-like cell expression (CD68), and extracellular matrix remodeling, evaluated by Masson staining. Importantly, both the pro-inflammatory substrate and extracellular matrix remodeling were ameliorated by swimming exercise training. Additionally, serum biochemical analysis demonstrated elevated levels of low-density lipoprotein cholesterol and Apolipoprotein B following MCT treatment, which were reduced with exercise intervention. Moreover, exercise enhanced systemic insulin sensitivity in both MCT-treated and untreated rats. Notably, MCT and exercise treatment both decreased fasting blood glucose (FBG) levels in rats, whereas exercise training reinstated FBG levels to normal in MCT-treated rats. In summary, our study suggests that swimming exercise confers a pulmonary protective effect in MCT-induced PAH rats, highlighting the potential importance of exercise-based rehabilitation in the management of PAH.

Myeloid NCOA4 sequesters KEAP1 to reduce ferroptosis for protection against salmonellosis in mice.

Salmonellosis, caused by Salmonella enterica serovar Typhimurium, is a significant global threat. Host immunity limits bacterial replication by inducing hepcidin, which degrades ferroportin, reducing iron transfer. However, this boosts macrophage iron storage, aiding intracellular pathogens like Salmonella. Mice lacking ferritin heavy chain (FTH1) in myeloid cells suffer worsened Salmonella infection. Nuclear receptor co-activator 4 (NCOA4) regulates iron release via FTH1 degradation during low iron, but its role in salmonellosis is unclear. Here, we reveal that myeloid NCOA4 deficiency augments spleen iron levels and increases cellular iron accumulation, oxidative stress, and ferroptosis in bone marrow-derived macrophages. This deficiency also increases susceptibility to Salmonella-induced colitis in mice. Mechanistically, NCOA4 suppresses oxidative stress by directly binding to the E3 ubiquitin ligase Kelch-like ECH-associated protein 1 (KEAP1) and stabilizing the antioxidant transcription factor nuclear factor-erythroid 2-related factor 2 (NRF2). Activation of NRF2 protects myeloid NCOA4 knockout mice from Salmonella-induced colitis. Antioxidant Tempol and myeloid cell-targeted curcumin offer protection against colitis in myeloid NCOA4-deficient mice. A low iron diet and ferroptosis inhibition also mitigate the heightened colitis in these mice. Overexpression of myeloid cell-specific NCOA4 confers protection against Salmonella-induced colitis via upregulating NRF2 signaling. Serum iron was reduced in myeloid NCOA4-overexpressing mice, but not in NCOA4-deficient mice. Targeted serum metabolomics analysis revealed that many lipids were decreased in myeloid NCOA4-deficient mice, while several of them were increased in myeloid NCOA4-overexpressing mice. Together, this study not only advances our understanding of NCOA4/KEAP1/NRF2/ferroptosis axis but also paves the way for novel myeloid cell-targeted therapies to combat salmonellosis.

Post-resolution macrophages shape long-term tissue immunity and integrity in a mouse model of pneumococcal pneumonia

Resolving inflammation is thought to return the affected tissue back to homoeostasis but recent evidence supports a non-linear model of resolution involving a phase of prolonged immune activity. Here we show that within days following resolution of Streptococcus pneumoniae-triggered lung inflammation, there is an influx of antigen specific lymphocytes with a memory and tissue-resident phenotype as well as macrophages bearing alveolar or interstitial phenotype. The transcriptome of these macrophages shows enrichment of genes associated with prostaglandin biosynthesis and genes that drive T cell chemotaxis and differentiation. Therapeutic depletion of post-resolution macrophages, inhibition of prostaglandin E2 (PGE2) synthesis or treatment with an EP4 antagonist, MF498, reduce numbers of lung CD4+/CD44+/CD62L+ and CD4+/CD44+/CD62L-/CD27+ T cells as well as their expression of the α-integrin, CD103. The T cells fail to reappear and reactivate upon secondary challenge for up to six weeks following primary infection. Concomitantly, EP4 antagonism through MF498 causes accumulation of lung macrophages and marked tissue fibrosis. Our study thus shows that PGE2 signalling, predominantly via EP4, plays an important role during the second wave of immune activity following resolution of inflammation. This secondary immune activation drives local tissue-resident T cell development while limiting tissue injury

Direct neuronal protection by the protease-activated receptor PAR4 antagonist ML354 after experimental stroke in mice.

Thrombo-inflammation is a key feature of stroke pathophysiology and provides multiple candidate drug targets. Thrombin exerts coagulation-independent actions via protease-activated receptors (PAR), of which PAR1 has been implicated in stroke-associated neuroinflammation. The role of PAR4 in this context is less clear. This study examined if the selective PAR4 antagonist ML354 provides neuroprotection in experimental stroke and explored the underlying mechanisms. Mouse primary cortical neurons were exposed to oxygen-glucose deprivation (OGD) and simulated reperfusion ± ML354. For comparison, functional Ca2+-imaging was performed upon acute stimulation with a PAR4 activating peptide or glutamate. Male mice underwent sham operation or transient middle cerebral artery occlusion (tMCAO), with ML354 or vehicle treatment beginning at recanalization. A subset of mice received a platelet-depleting antibody. Stroke size and functional outcomes were assessed. Abundance of target genes, proteins, and cell markers was determined in cultured cells and tissues by qPCR, immunoblotting, and immunofluorescence. Stroke up-regulated PAR4 expression in cortical neurons in vitro and in vivo. OGD augments spontaneous and PAR4-mediated neuronal activity; ML354 suppresses OGD-induced neuronal excitotoxicity and apoptosis. ML354 applied in vivo after tMCAO reduced infarct size, apoptotic markers, macrophage accumulation, and interleukin-1β expression. Platelet depletion did not affect infarct size in mice with tMCAO ± ML354. Selective PAR4 inhibition during reperfusion improves infarct size and neurological function after experimental stroke by blunting neuronal excitability, apoptosis, and local inflammation. PAR4 antagonists may provide additional neuroprotective benefits in patients with acute stroke beyond their canonical antiplatelet action.