The study of macrophage heterogeneity in the peritoneal cavity

Mononuclear phagocytes play a key role in tissue homeostasis and in host defense against pathogen invasion. However, the phenotypic identities and functional properties of this heterogeneous population within the peritoneal cavity remains poorly elucidated. In the context of peritoneal dialysis, it is hypothesized that the modification of macrophage/dendritic cell biology by the dialysis process would alter tissue homeostasis, host susceptibility to infection and local immunity, compromising long-term outcomes of the patients. The research work carried out in this thesis has tested this hypothesis by examination of the immunobiology (mainly phenotype and function) of human and murine peritoneal macrophage and dendritic cell subsets. Moreover, the potential link between the altered immunobiology of peritoneal mononuclear phagocytes and clinical outcomes of the dialysis patients has been investigated. Several key findings were generated during these studies: 1) multiple discrete peritoneal macrophage and dendritic cell subsets have been phenotypically identified in humans (from different clinical settings of peritoneal dialysis) and in mice (from naïve and inflamed conditions); 2) in humans, the phenotypes and the activation/maturation status of peritoneal macrophages and dendritic cells are modified throughout the dialysis course and also during acute peritonitis; some characteristic alterations are associated with adverse patient outcomes; 3) in mice, the distinctive kinetics of the respective peritoneal macrophage and dendritic cell subsets in clinically relevant acute peritonitis models have been characterized; 4) individual peritoneal macrophage and dendritic cell subsets (human and mice) display differences in their phagocytic capacity and the ability to process and present antigen

Systems approaches to cell culture-derived extracellular vesicles for acute kidney injury therapy: Prospects and challenges

Acute kidney injury (AKI) is a heterogeneous syndrome, comprising diverse etiologies of kidney insults that result in high mortality and morbidity if not well managed. Although great efforts have been made to investigate underlying pathogenic mechanisms of AKI, there are limited therapeutic strategies available. Extracellular vesicles (EV) are membrane-bound vesicles secreted by various cell types, which can serve as cell-free therapy through transfer of bioactive molecules. In this review, we first overview the AKI syndrome and EV biology, with a particular focus on the technical aspects and therapeutic application of cell culture-derived EVs. Second, we illustrate how multi-omic approaches to EV miRNA, protein, and genomic cargo analysis can yield new insights into their mechanisms of action and address unresolved questions in the field. We then summarize major experimental evidence regarding the therapeutic potential of EVs in AKI, which we subdivide into stem cell and non-stem cell-derived EVs. Finally, we highlight the challenges and opportunities related to the clinical translation of animal studies into human patients

A Chinese Herbal Decoction, Modified Yi Guan Jian, Induces Apoptosis in Hepatic Stellate Cells through an ROS-Mediated Mitochondrial/Caspase Pathway

The Chinese herb modified Yi Guan Jian (mYGJ) is an effective regimen that is usually used in outpatients with chronic liver diseases such as fibrosis and cirrhosis. However, the mechanism for the action of mYGJ on liver fibrosis is not yet clear. In this study, we found that mYGJ induced hepatic stellate cells (HSCs) apoptosis concomitant with the downregulation of Bcl-2 expression and slight elevation of Bax level. Moreover, the reactive oxygen species (ROS) were generated in the early stages of mYGJ-induced HSCs apoptosis to facilitate calcium and cytochrome c release from the mitochondria to cytosol. Subsequently, caspase 9 and caspase 3 were activated. Furthermore, the activation of ER stress-associated caspase 12 in HSCs was also evaluated. Together, we report the first evidence-based study to demonstrate that mYGJ decoction induces HSCs apoptosis through ROS accumulation and the intrinsic apoptosis pathway. These findings provide rationale for further clinical investigation of traditional Chinese medicine recipes against liver fibrosis

Effect of 24-h blood pressure dysregulations and reduced ocular perfusion pressure in open-angle glaucoma progression

Background: Low ocular perfusion pressure (OPP), which depends on the mean arterial pressure (MAP) and intraocular pressure (IOP), is associated with glaucoma. We studied 24-h MAP dysregulations and OPP in relation to the progression of glaucoma damage. Methods: We retrospectively analyzed 155 normal-tension glaucoma (NTG) and 110 primary open-angle glaucoma (POAG) patients aged 18 years old followed at the University Hospital Leuven with repeated visual field tests (n = 7000 measures, including both eyes) who underwent 24-h ambulatory blood pressure monitoring. Twenty-four-hour MAP dysregulations were variability independent of the mean (VIM), and the five lowest dips in MAP readings over 24 h. OPP was the difference between 2/3 of the MAP and IOP. Glaucoma progression was the deterioration of the visual field, expressed as decibel (dB) changes in mean deviation analyzed by applying multivariable linear mixed regression models. Results: The mean age was 68 years (53% were women). High 24-h VIMmap was associated with glaucoma progression in POAG (P \u3c 0.001) independently of the 24-h MAP level. The estimated changes in mean deviation in relation to dip MAP measures ranged from −2.84 dB [95% confidence interval (CI) −4.12 to −1.57] to −2.16 dB (95% CI −3.46 to −0.85) in POAG. Reduced OPP along with high variability and dips in MAP resulted in worse mean deviation deterioration. Conclusion: The progression of glaucoma damage associates with repetitive and extreme dips in MAP caused by high variability in MAP throughout 24 h. This progression exacerbates if 24-h MAP dysregulations occur along with reduced OPP

IL-10 differentially controls the infiltration of inflammatory macrophages and antigen-presenting cells during inflammation

The inflammatory activation and recruitment of defined myeloid populations is essential for controlling the bridge between innate and adaptive immunity and shaping the immune response to microbial challenge. However, these cells exhibit significant functional heterogeneity and the inflammatory signals that differentially influence their effector characteristics are poorly characterized. In this study, we defined the phenotype of discrete subsets of effective antigen-presenting cells (APCs) in the peritoneal cavity during peritonitis. When the functional properties of these cells were compared to inflammatory monocyte-derived macrophages we noted differential responses to the immune-modulatory cytokine IL-10. In contrast to the suppressive actions of IL-10 on inflammatory macrophages, the recruitment of APCs was relatively refractory and we found no evidence for selective inhibition of APC differentiation. This differential response of myeloid cell subsets to IL-10 may thus have limited impact on development of potentially tissue-damaging adaptive immune responses, whilst restricting the magnitude of the inflammatory response. These findings may have clinical relevance in the context of peritoneal dialysis patients, where recurrent infections are associated with immune-mediated membrane dysfunction, treatment failure and increased morbidity

Distinct immunomodulation elicited by young versus aged extracellular vesicles in bone marrow-derived macrophages

Background: Previous research has indicated that extracellular vesicles (EVs) potentially play significant roles in multiple ageing phenotypes. This study uses a factorial experimental design to explore the interactions between circulating EVs and bone marrow-derived macrophages (BMDMs) isolated from young (7–12 weeks) and aged (70–90 weeks) mice. Results: In this study, plasma EVs from young (Y_EV) and aged (O_EV) mice were isolated and compared based on abundance, size, and miRNA cargo. Compared to some previous studies, we found relatively few differences in EV miRNA cargo between Y_EVs and O_EVs. Young and old EVs were then used to stimulate naïve BMDMs isolated from young (Y_BMDM) and aged (O_BMDM) mice. A panel of five “M1” and six “M2” macrophage markers were used to assess the degree of polarisation. Our results revealed differences in the immunomodulatory effects of Y_EVs and O_EVs in Y_BMDMs and O_BMDMs. Y_EVs induced less pro-inflammatory gene expression, while O_EVs exhibited a more varied impact, promoting both pro- and anti-inflammatory markers. However, neither EV population induced a clearly defined ‘M1’ or ‘M2’ macrophage phenotype. We also report that EVs elicited responses that differed markedly from those induced by whole plasma. Plasma from old mice had strong pro-inflammatory effects on Y_BMDMs, increasing Il1b, Nlrp3 and Tnfa. However, O_EVs did not have these effects, supporting current evidence that EVs are a separate component of circulating factors during ageing. More research is needed to elucidate specific factors involved in inflammageing processes. Conclusions: Our findings reveal age-related differences in EV cargo and function, with young EVs tending to suppress inflammatory markers more effectively than aged EVs. However, this is not straightforward, and EVs often promoted both M1 and M2 markers. These results suggest that EVs are a distinct component of circulating factors and hold potential for therapeutic strategies aimed at mitigating age-related inflammation and immune dysregulation

Cost-effectiveness of Intensive vs Standard Blood Pressure Control Among Older Patients With Hypertension

IMPORTANCE: Older patients with hypertension receiving intensive systolic blood pressure control (110-130 mm Hg) have lower incidences of cardiovascular events than those receiving standard control (130-150 mm Hg). Nevertheless, the mortality reduction is insignificant, and intensive blood pressure management results in more medical costs from treatments and subsequent adverse events. OBJECTIVE: To examine the incremental lifetime outcomes, costs, and cost-effectiveness of intensive vs standard blood pressure control in older patients with hypertension from the health care payer's perspective. DESIGN, SETTING, AND PARTICIPANTS: This economic analysis was conducted with a Markov model to examine the cost-effectiveness of intensive blood pressure management among patients aged 60 to 80 years with hypertension. Treatment outcome data from the Trial of Intensive Blood-Pressure Control in Older Patients With Hypertension (STEP trial) and different cardiovascular risk assessment models for a hypothetical cohort of STEP-eligible patients were used. Costs and utilities were obtained from published sources. The incremental cost-effectiveness ratio (ICER) against the willingness-to-pay threshold was used to evaluate whether the management was cost-effective. Extensive sensitivity, subgroup, and scenario analyses were performed to address uncertainty. The US and UK population using race-specific cardiovascular risk models were conducted in the generalizability analysis. Data for the STEP trial were collected from February 10 to March 10, 2022, and were analyzed for the present study from March 10 to May 15, 2022. INTERVENTIONS: Hypertension treatments with a systolic blood pressure target of 110 to 130 mm Hg or 130 to 150 mm Hg. MAIN OUTCOMES AND MEASURES: Incremental lifetime quality-adjusted life-years (QALYs), costs, and ICER are discounted at the given rates annually. RESULTS: After simulating 10 000 STEP-eligible patients assumed to be 66 years of age (4650 men [46.5%] and 5350 women [53.5%]) in the model, the ICER values were ¥51 675 ($12 362) per QALY gained in China,$25 417 per QALY gained in the US, and £4679 ($7004) per QALY gained in the UK. Simulations projected that the intensive management in China being cost-effective were 94.3$21 364]/QALY) and 3 times (¥267 900 [$64 090]/QALY) the gross domestic product per capita, respectively. The US had 86.9$50 000/QALY and $100 000/QALY, respectively, and the UK had 99.1$29 940)/QALY and £30 000 ($44 910)/QALY, respectively. CONCLUSIONS AND RELEVANCE: In this economic evaluation, the intensive systolic blood pressure control in older patients produced fewer cardiovascular events and had acceptable costs per QALY gained, well below the typical willingness-to-pay thresholds. The cost-effective advantages of intensive blood pressure management in older patients were consistent over various clinical scenarios across different countries

Cardiovascular risk of metabolically healthy obesity in two european populations: Prevention potential from a metabolomic study

Background: A new definition of metabolically healthy obesity (MHO) has recently been proposed to stratify the heterogeneous mortality risk of obesity. Metabolomic profiling provides clues to metabolic alterations beyond clinical definition. We aimed to evaluate the association between MHO and cardiovascular events and assess its metabolomic pattern. Methods: This prospective study included Europeans from two population-based studies, the FLEMENGHO and the Hortega study. A total of 2339 participants with follow-up were analyzed, including 2218 with metabolomic profiling. Metabolic health was developed from the third National Health and Nutrition Examination Survey and the UK biobank cohorts and defined as systolic blood pressure < 130 mmHg, no antihypertensive drugs, waist-to-hip ratio < 0.95 for women or 1.03 for men, and the absence of diabetes. BMI categories included normal weight, overweight, and obesity (BMI < 25, 25-30, ≥ 30 kg/m2). Participants were classified into six subgroups according to BMI category and metabolic healthy status. Outcomes were fatal and nonfatal composited cardiovascular events. Results: Of 2339 participants, the mean age was 51 years, 1161 (49.6%) were women, 434 (18.6%) had obesity, 117 (5.0%) were classified as MHO, and both cohorts had similar characteristics. Over a median of 9.2-year (3.7-13.0) follow-up, 245 cardiovascular events occurred. Compared to those with metabolically healthy normal weight, individuals with metabolic unhealthy status had a higher risk of cardiovascular events, regardless of BMI category (adjusted HR: 3.30 [95% CI: 1.73-6.28] for normal weight, 2.50 [95% CI: 1.34-4.66] for overweight, and 3.42 [95% CI: 1.81-6.44] for obesity), whereas those with MHO were not at increased risk of cardiovascular events (HR: 1.11 [95% CI: 0.36-3.45]). Factor analysis identified a metabolomic factor mainly associated with glucose regulation, which was associated with cardiovascular events (HR: 1.22 [95% CI: 1.10-1.36]). Individuals with MHO tended to present a higher metabolomic factor score than those with metabolically healthy normal weight (0.175 vs. -0.057, P = 0.019), and the score was comparable to metabolically unhealthy obesity (0.175 vs. -0.080, P = 0.91). Conclusions: Individuals with MHO may not present higher short-term cardiovascular risk but tend to have a metabolomic pattern associated with higher cardiovascular risk, emphasizing a need for early intervention.The work was supported by Internal Funds KU Leuven (STG-18-00379), the European Research Area Net for Cardiovascular Diseases (JTC2017-046-PROACT), the Ministerio de Ciencia e Innovación of Spain (PID2019-108973RB-C21 and C22 and PCIN2017-117), the Generalitat Valenciana of Spain (GV/2020/048), and GUTMOM (INTIMIC-085) from the EU Joint Programming Initiative Healthy Diet Healthy Life (HDHL).S