A flow cytometry approach reveals heterogeneity in conventional subsets of murine renal mononuclear phagocytes

Priming Mesenchymal Stem Cells with Lipopolysaccharide Boosts the Immunomodulatory and Regenerative Activity of Secreted Extracellular Vesicles

Background: Mesenchymal stem cells (MSCs)-derived extracellular vesicles (EVs) have been proposed as an alternative to live-cell administration for Acute Respiratory Distress Syndrome (ARDS). MSC-EVs can be chiefly influenced by the environment to which the MSCs are exposed. Here, lipopolysaccharide (LPS) priming of MSCs was used as a strategy to boost the natural therapeutic potential of the EVs in acute lung injury (ALI). Methods: The regenerative and immunemodulatory effect of LPS-primed MSC-EVs (LPS-EVs) and non-primed MSC-EVs (C-EVs) were evaluated in vitro on alveolar epithelial cells and macrophage-like THP-1 cells. In vivo, ALI was induced in adult male rats by the intrapulmonary instillation of HCl and LPS. Rats (n = 8 to 22/group) were randomized to receive a single bolus (1 × 108 particles) of LPS-EVs, C-EVs, or saline. Lung injury severity was assessed at 72 h in lung tissue and bronchoalveolar lavage. Results: In vitro, LPS-EVs improved wound regeneration and attenuated the inflammatory response triggered by the P. aeruginosa infection, enhancing the M2 macrophage phenotype. In in vivo studies, LPS-EVs, but not C-EVs, significantly decreased the neutrophilic infiltration and myeloperoxidase (MPO) activity in lung tissue. Alveolar macrophages from LPS-EVs-treated animals exhibited a reduced expression of CXCL-1, a key neutrophil chemoattractant. However, both C-EVs and LPS-EVs reduced alveolar epithelial and endothelial permeability, mitigating lung damage. Conclusions: EVs from LPS-primed MSCs resulted in a better resolution of ALI, achieving a greater balance in neutrophil infiltration and activation, while avoiding the complete disruption of the alveolar barrier. This opens new avenues, paving the way for the clinical implementation of cell-based therapies.

Machine Learning-Assisted Near-Infrared Spectral Fingerprinting for Macrophage Phenotyping

Spectral fingerprinting has emerged as a powerful tool that is adept at identifying chemical compounds and deciphering complex interactions within cells and engineered nanomaterials. Using near-infrared (NIR) fluorescence spectral fingerprinting coupled with machine learning techniques, we uncover complex interactions between DNA-functionalized single-walled carbon nanotubes (DNA-SWCNTs) and live macrophage cells, enabling in situ phenotype discrimination. Utilizing Raman microscopy, we showcase statistically higher DNA-SWCNT uptake and a significantly lower defect ratio in M1 macrophages compared to M2 and naive phenotypes. NIR fluorescence data also indicate that distinctive intraendosomal environments of these cell types give rise to significant differences in many optical features, such as emission peak intensities, center wavelengths, and peak intensity ratios. Such features serve as distinctive markers for identifying different macrophage phenotypes. We further use a support vector machine (SVM) model trained on SWCNT fluorescence data to identify M1 and M2 macrophages, achieving an impressive accuracy of >95%. Finally, we observe that the stability of DNA-SWCNT complexes, influenced by DNA sequence length, is a crucial consideration for applications, such as cell phenotyping or mapping intraendosomal microenvironments using AI techniques. Our findings suggest that shorter DNA-sequences like GT6 give rise to more improved model accuracy (>87%) due to increased active interactions of SWCNTs with biomolecules in the endosomal microenvironment. Implications of this research extend to the development of nanomaterial-based platforms for cellular identification, holding promise for potential applications in real time monitoring of in vivo cellular differentiation.

Pathological mechanism of immune disorders in diabetic kidney disease and intervention strategies

Diabetic kidney disease is one of the most severe chronic microvascular complications of diabetes and a primary cause of end-stage renal disease. Clinical studies have shown that renal inflammation is a key factor determining kidney damage during diabetes. With the development of immunological technology, many studies have shown that diabetic nephropathy is an immune complex disease, and that most patients have immune dysfunction. However, the immune response associated with diabetic nephropathy and autoimmune kidney disease, or caused by ischemia or infection with acute renal injury, is different, and has a com-plicated pathological mechanism. In this review, we discuss the pathogenesis of diabetic nephropathy in immune disorders and the intervention mechanism, to provide guidance and advice for early intervention and treatment of diabetic nephropathy.

L-AP Alleviates Liver Injury in Septic Mice by Inhibiting Macrophage Activation via Suppressing NF-κB and NLRP3 Inflammasome/Caspase-1 Signal Pathways

Liver injury and progressive liver failure are severe life-threatening complications in sepsis, further worsening the disease and leading to death. Macrophages and their mediated inflammatory cytokine storm are critical regulators in the occurrence and progression of liver injury in sepsis, for which effective treatments are still lacking. l-Ascorbic acid 6-palmitate (L-AP), a food additive, can inhibit neuroinflammation by modulating the phenotype of the microglia, but its pharmacological action in septic liver damage has not been fully explored. We aimed to investigate L-AP's antisepticemia action and the possible pharmacological mechanisms in attenuating septic liver damage by modulating macrophage function. We observed that L-AP treatment significantly increased survival in cecal ligation and puncture-induced WT mice and attenuated hepatic inflammatory injury, including the histopathology of the liver tissues, hepatocyte apoptosis, and the liver enzyme levels in plasma, which were comparable to NLRP3-deficiency in septic mice. L-AP supplementation significantly attenuated the excessive inflammatory response in hepatic tissues of septic mice in vivo and in cultured macrophages challenged by both LPS and ATP in vitro, by reducing the levels of NLRP3, pro-IL-1β, and pro-IL-18 mRNA expression, as well as the levels of proteins for p-I-κB-α, p-NF-κB-p65, NLRP3, cleaved-caspase-1, IL-1β, and IL-18. Additionally, it impaired the inflammasome ASC spot activation and reduced the inflammatory factor contents, including IL-1β and IL-18 in plasma/cultured superannuants. It also prevented the infiltration/migration of macrophages and their M1-like inflammatory polarization while improving their M2-like polarization. Overall, our findings revealed that L-AP protected against sepsis by reducing macrophage activation and inflammatory cytokine production by suppressing their activation in NF-κB and NLRP3 inflammasome signal pathways in septic liver.

Machine Learning Assisted Spectral Fingerprinting for Immune Cell Phenotyping

Spectral fingerprinting has emerged as a powerful tool, adept at identifying chemical compounds and deciphering complex interactions within cells and engineered nanomaterials. Using near-infrared (NIR) fluorescence spectral fingerprinting coupled with machine learning techniques, we uncover complex interactions between DNA-functionalized single-walled carbon nanotubes (DNA-SWCNTs) and live macrophage cells, enabling in situ phenotype discrimination. Through the use of Raman microscopy, we showcase statistically higher DNA-SWCNT uptake and a significantly lower defect ratio in M1 macrophages as compared to M2 and naïve phenotypes. NIR fluorescence data also indicate that distinctive intra-endosomal environments of these cell types give rise to significant differences in many optical features such as emission peak intensities, center wavelengths, and peak intensity ratios. Such features serve as distinctive markers for identifying different macrophage phenotypes. We further use a support vector machine (SVM) model trained on SWCNT fluorescence data to identify M1 and M2 macrophages, achieving an impressive accuracy of > 95%. Finally, we observe that the stability of DNA-SWCNT complexes, influenced by DNA sequence length, is a crucial consideration for applications such as cell phenotyping or mapping intra-endosomal microenvironments using AI techniques. Our findings suggest that shorter DNA-sequences like GT 6 give rise to more improved model accuracy (> 87%) due to increased active interactions of SWCNTs with biomolecules in the endosomal microenvironment. Implications of this research extend to the development of nanomaterial-based platforms for cellular identification, holding promise for potential applications in real time monitoring of in vivo cellular differentiation.

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Improving combination cancer immunotherapy by manipulating dual immunomodulatory signals with enzyme-triggered, cell-penetrating peptide-mediated biomodulators

Immunosuppressive tumor microenvironments challenge the effectiveness of protein-based biopharmaceuticals in cancer immunotherapy. Reestablishing tumor cell immunogenicity by enhancing calreticulin (CRT) exposure is expected to improve tumor immunotherapy. Given that CRT translocation is inherently modulated by phosphorylated eIF2α, the selective inhibition of protein phosphatase 1 (PP1) emerges as an effective strategy to augment tumor immunogenicity. To harness the PP1-disrupting potential of GADD34-derived motifs and address their limited intracellular delivery, we integrated these sequences into an enzyme-triggered, cell-penetrating peptide-mediated chimeric protein scaffold. This design not only facilitates efficient cytoplasmic delivery of these immunostimulatory motifs to induce "eat-me" signaling, but also provides a versatile platform for combination immunotherapy. Fabrication of biomodulators with cytotoxic BLF1 provides additional "eat-me" signaling through phosphatidylserine exposure or that with an immunomodulatory designed ankyrin repeat protein disables "don't-find-me" signaling by antagonizing PD-L1. Notably, these bifunctional biomodulators exhibit remarkable ability to induce macrophage phagocytosis, dendritic cell maturation, and CD8+ T activation, ultimately substantially inhibiting tumor growth. This study presents a modular genetic coding strategy for PP1-centered therapies that enables seamless integration of immunostimulatory sequences into protein-based anti-tumor cocktail therapies, thereby offering novel alternatives for improving antitumor efficacy.

Immunomodulatory amnion-derived mesenchymal stromal cells preserve muscle function in a mouse model of Duchenne muscular dystrophy

BACKGROUND

Duchenne muscular dystrophy (DMD) is an incurable genetic disease characterized by degeneration and necrosis of myofibers, chronic inflammation, and progressive muscle weakness resulting in premature mortality. Immunosuppressive multipotent mesenchymal stromal cell (MSC) therapy could be an option for DMD patients. We focused on amnion-derived mesenchymal stromal cells (AMSCs), a clinically viable cell source owing to their unique characteristics, such as non-invasive isolation, mitotic stability, ethical acceptability, and minimal risk of immune reaction and cancer. We aimed to identify novel immunomodulatory effects of AMSCs on macrophage polarization and their transplantation strategies for the functional recovery of skeletal and cardiac muscles.

METHODS

We used flow cytometry to analyze the expression of anti-inflammatory M2 macrophage markers on peripheral blood mononuclear cells (PBMCs) co-cultured with human AMSCs (hAMSCs). hAMSCs were intravenously injected into DMD model mice (mdx mice) to assess the safety and efficacy of therapeutic interventions. hAMSC-treated and untreated mdx mice were monitored using blood tests, histological examinations, spontaneous wheel-running activities, grip strength, and echocardiography.

RESULTS

hAMSCs induced M2 macrophage polarization in PBMCs via prostaglandin E₂ production. After repeated systemic hAMSC injections, mdx mice exhibited a transient downregulation of serum creatin kinase. Limited mononuclear cell infiltration and a decreased number of centrally nucleated fibers were indicative of regenerated myofibers following degeneration, suggesting an improved histological appearance of the skeletal muscle of hAMSC-treated mdx mice. Upregulated M2 macrophages and altered cytokine/chemokine expressions were observed in the muscles of hAMSC-treated mdx mice. During long-term experiments, a significant decrease in the grip strength in control mdx mice significantly improved in the hAMSC-treated mdx mice. hAMSC-treated mdx mice maintained running activity and enhanced daily running distance. Notably, the treated mice could run longer distances per minute, indicating high running endurance. Left ventricular function in DMD mice improved in hAMSC-treated mdx mice.

CONCLUSIONS

Early systemic hAMSC administration in mdx mice ameliorated progressive phenotypes, including pathological inflammation and motor dysfunction, resulting in the long-term improvement of skeletal and cardiac muscle function. The therapeutic effects might be associated with the immunosuppressive properties of hAMSCs via M2 macrophage polarization. This treatment strategy could provide therapeutic benefits to DMD patients.

The Response of Macrophages in Sepsis-Induced Acute Kidney Injury

Sepsis-induced acute kidney injury (SAKI) is common in critically ill patients and often leads to poor prognosis. At present, the pathogenesis of SAKI has not been fully clarified, and there is no effective treatment. Macrophages are immune cells that play an important role in the pathogenesis of SAKI. The phenotype and role of macrophages can vary from early to later stages of SAKI. Elucidating the role of macrophages in SAKI will be beneficial to its diagnosis and treatment. This article reviews past studies describing the role of macrophages in SAKI, with the aim of identifying novel therapeutic targets.

The single-cell landscape of kidney immune cells reveals transcriptional heterogeneity in early diabetic kidney disease

The pathogenesis of diabetic kidney disease (DKD) involves multifactorial processes that converge to initiate and advance the disease. Although DKD is not typically classified as an inflammatory glomerular disease, mounting evidence supports the involvement of kidney inflammation as a key contributor in DKD pathogenesis, particularly through macrophages. However, detailed identification and corresponding phenotypic changes of macrophages in DKD remain poorly understood. To capture the gene expression changes in specific macrophage cell subsets in early DKD, we performed single-cell transcriptomic analysis of CD45-enriched kidney immune cells from type 1 diabetic OVE26 mice at two time points during the disease development. We also undertook a focused analysis of mononuclear phagocytes (macrophages and dendritic cells). Our results show increased resident and infiltrating macrophage subsets in the kidneys of mice with diabetes over time, with heightened expression of pro-inflammatory or anti-inflammatory genes in a subset-specific manner. Further analysis of macrophage polarization states in each subset in the kidneys showed changes consistent with the continuum of activation and differentiation states, with gene expression tending to shift toward undifferentiated phenotypes but with increased M1-like inflammatory phenotypes over time. By deconvolution analysis of RNAseq samples and by immunostaining of biopsies from patients with DKD, we further confirmed a differential expression of select genes in specific macrophage subsets essentially recapitulating the studies in mice. Thus, our study provides a comprehensive analysis of macrophage transcriptomic profiles in early DKD that underscores the dynamic macrophage phenotypes in disease progression.

Prim-O-glucosycimifugin attenuates liver injury in septic mice by inhibiting NLRP3 inflammasome/caspase-1 signaling cascades in macrophages

BACKGROUND

Liver dysfunction and liver failure are serious complications of sepsis, directly leading to septic progression and death. Now, there is no specific therapeutics available for sepsis-related liver dysfunction. Prim-O-glucosylcimifugin (POG), a chromone richest in the roots of Saposhnikovia divaricata (Turcz.) Schischk, is usually used to treat headache, rheumatoid arthritis and tetanus. While, the underlying mechanisms of POG against sepsis-induced liver damage and dysfunction are still not clear.

PURPOSE

To study the anti-sepsis effect of POG, and its pharmacological mechanism to protect liver injury by weakening the function of macrophages in septic livers through inhibiting NOD-like receptor protein 3 (NLRP3) inflammasome pathway.

METHOD

In vivo experiments, septic mouse model was induced by cecal ligation and puncture (CLP), and then the mortality was detected, liver inflammatory damages and plasma biomarkers of liver injury were evaluated by histopathological staining and biochemical assays, respectively. In vitro experiments, mouse primary peritoneal macrophages were treated with lipopolysaccharide (LPS) and ATP, and then the activated-inflammasomes, macrophage migration and polarization were detected by ASC immunofluorescence staining, transwell and flow cytometry assays, respectively. NLRP3 inflammasome components NLRP3, caspase-1, IL-1β and IL-18 protein expressions were detected using western blot assays, and the contents of IL-1β and IL-18 were measured by ELISA assays.

RESULTS

POG treatment significantly decreased the mortality, liver inflammatory damages, hepatocyte apoptosis and plasma biomarkers of liver injury in CLP-challenged male WT mice, which were comparable to those in ibuprofen (a putative anti-inflammatory drug)-supplemented septic male WT mice and septic NLRP3 deficient-male mice. POG supplementation significantly suppressed NLRP3 inflammasome activation in septic liver tissues and cultured macrophages, by significantly reducing NLRP3, cleaved-caspase-1, IL-1β and IL-18 levels, the activated-inflammasome ASC specks, and macrophage infiltration and migration, as well as M1-like polarization, but significantly increasing M2-like polarization. These findings were similar to the pharmacological effects of ibuprofen, NLRP3 deficiency, and a special NLRP3 inhibitor, MCC950.

CONCLUSION

POG protected against sepsis by inhibiting NLRP3 inflammasome-mediated macrophage activation in septic liver and attenuating liver inflammatory injury, indicating that it may be a potential anti-sepsis drug candidate.

Three-Dimensional Visualization With Tissue Clearing Uncovers Dynamic Alterations of Renal Resident Mononuclear Phagocytes After Acute Kidney Injury

Traditional histologic methods are limited in detecting dynamic changes in immune cells during acute kidney injury (AKI). Recently, optical tissue clearing combined with multiphoton microscopy (MPM) or light sheet fluorescence microscopy (LSFM) has become an emerging method for deep tissue evaluation and three-dimensional visualization. These new approaches have helped expand our understanding of tissue injury and repair processes, including tracing the changes in immune cells. We designed this study to investigate the morphological and functional alterations of renal mononuclear phagocytes (MNPs) in lipopolysaccharide (LPS)-induced AKI using renal clearing in CD11c-YFP mice. We also evaluated the effect of the NLRP3 inhibitor MCC950 to determine whether NLRP3 inhibition attenuates the activation of CD11c+ cells in an LPS-induced AKI model. Transverse sectioned whole mouse kidney imaging by LSFM showed that CD11c+ cells were mainly distributed in the cortex, especially the tubulointerstitial area. The number of CD11c+ cells was significantly more densely interspersed, particularly in periglomerular and perivascular lesions, in the saline-treated LPS-exposed kidney than in the control kidney. Deep imaging of the kidney cortex by MPM demonstrated an increased number of CD11c+ cells in the saline-treated LPS group compared with the control group. This quantitative alteration of CD11c+ cells in AKI was accompanied by morphological changes at high resolution, showing an increased number and level of dendrites. These morphological and behavioral changes in the saline-treated LPS group were accompanied by increased MHC class II and CD86 on CD11c-YFP+ cells. MCC950 attenuated the activation of CD11c+ cells after AKI and improved renal function. In conclusion, wide and deep three-dimensional visualization using MPM or LSFM combined with kidney clearing uncovers dynamic changes of renal MNPs, which are directly linked to renal function in AKI.

Direct Blood Pressure-Independent Anti-Fibrotic Effects by the Selective Nonsteroidal Mineralocorticoid Receptor Antagonist Finerenone in Progressive Models of Kidney Fibrosis

INTRODUCTION

The nonsteroidal mineralocorticoid receptor (MR) antagonist finerenone and sodium-glucose cotransporter-2 (SGLT2) inhibitors have demonstrated clinical benefits in chronic kidney disease patients with type 2 diabetes. Precise molecular mechanisms responsible for these benefits are incompletely understood. Here, we investigated potential direct anti-fibrotic effects and mechanisms of nonsteroidal MR antagonism by finerenone or SGLT2 inhibition by empagliflozin in 2 relevant mouse kidney fibrosis models: unilateral ureter obstruction and sub-chronic ischemia reperfusion injury.

METHODS

Kidney fibrosis was induced in mice via unilateral ureteral obstruction or ischemia. In a series of experiments, mice were treated orally with the MR antagonist finerenone (3 or 10 mg/kg), the SGLT2 inhibitor empagliflozin (10 or 30 mg/kg), or in a direct comparison of both drugs. Interstitial myofibroblast accumulation was quantified via alpha-smooth muscle actin and interstitial collagen deposition via Sirius Red/Fast Green staining in both models. Secondary analyses included the assessment of inflammatory cells, kidney mRNA expression of fibrotic markers as well as functional parameters (serum creatinine and albuminuria) in the ischemic model. Blood pressure was measured via telemetry in healthy conscious compound-treated animals.

RESULTS

Finerenone dose-dependently decreased pathological myofibroblast accumulation and collagen deposition with no effects on systemic blood pressure and inflammatory markers in the tested dose range. Reduced kidney fibrosis was paralleled by reduced kidney plasminogen activator inhibitor-1 (PAI-1) and naked cuticle 2 (NKD2) expression in finerenone-treated mice. In contrast, treatment with empagliflozin strongly increased urinary glucose excretion in both models and reduced ischemia-induced albuminuria but had no effects on kidney myofibroblasts or collagen deposition.

DISCUSSION/CONCLUSION

Finerenone has direct anti-fibrotic properties resulting in reduced myofibroblast and collagen deposition accompanied by a reduction in renal PAI-1 and NKD2 expression in mouse models of progressive kidney fibrosis at blood pressure-independent dosages.