Mesenchymal Stromal Cell (MSC) Functional Analysis-Macrophage Activation and Polarization Assays.

Stem cell-based therapies have evolved to become a key component of regenerative medicine approaches to human pathologies. Exogenous stem cell transplantation takes advantage of the potential of stem cells to self-renew, differentiate, home to sites of injury, and sufficiently evade the immune system to remain viable for the release of anti-inflammatory cytokines, chemokines, and growth factors. Common to many pathologies is the exacerbation of inflammation at the injury site by proinflammatory macrophages. An increasing body of evidence has demonstrated that mesenchymal stromal cells (MSCs) can influence the immunophenotype and function of myeloid lineage cells to promote therapeutic effects. Understanding the degree to which MSCs can modulate the phenotype of macrophages within an inflammatory environment is of interest when considering strategies for targeted cell therapies. There is a critical need for potency assays to elucidate these intercellular interactions in vitro and provide insight into potential mechanisms of action attributable to the immunomodulatory and polarizing capacities of MSCs, as well as other cells with immunomodulatory potential. However, the complexity of the responses, in terms of cell phenotypes and characteristics, timing of these interactions, and the degree to which cell contact is involved, have made the study of these interactions challenging. To provide a research tool to study the direct interactions between MSCs and macrophages, we developed a potency assay that directly co-cultures MSCs with naïve macrophages under proinflammatory conditions. Using this assay, we demonstrated changes in the macrophage secretome and phenotype, which can be used to evaluate the abilities of the cell samples to influence the cell microenvironment. These results suggest the immunomodulatory effects of MSCs on macrophages while revealing key cytokines and phenotypic changes that may inform their efficacy as potential cellular therapies. Key features • The protocol uses monocytes differentiated into naïve macrophages, which are loosely adherent, have a relatively homogeneous genetic background, and resemble peripheral blood mononuclear cells-derived macrophages. • The protocol requires a plate reader and a flow cytometer with the ability to detect six fluorophores. • The protocol provides a quantitative measurement of co-culture conditions by the addition of a fixed number of freshly thawed or culture-rescued MSCs to macrophages. • This protocol uses assessment of the secretome and cell harvest to independently verify the nature of the interactions between macrophages and MSCs.

Osteoinductive micro-nano guided bone regeneration membrane for in situ bone defect repair.

BACKGROUND: Biomaterials used in bone tissue engineering must fulfill the requirements of osteoconduction, osteoinduction, and osseointegration. However, biomaterials with good osteoconductive properties face several challenges, including inadequate vascularization, limited osteoinduction and barrier ability, as well as the potential to trigger immune and inflammatory responses. Therefore, there is an urgent need to develop guided bone regeneration membranes as a crucial component of tissue engineering strategies for repairing bone defects. METHODS: The mZIF-8/PLA membrane was prepared using electrospinning technology and simulated body fluid external mineralization method. Its ability to induce biomimetic mineralization was evaluated through TEM, EDS, XRD, FT-IR, zeta potential, and wettability techniques. The biocompatibility, osteoinduction properties, and osteo-immunomodulatory effects of the mZIF-8/PLA membrane were comprehensively evaluated by examining cell behaviors of surface-seeded BMSCs and macrophages, as well as the regulation of cellular genes and protein levels using PCR and WB. In vivo, the mZIF-8/PLA membrane's potential to promote bone regeneration and angiogenesis was assessed through Micro-CT and immunohistochemical staining. RESULTS: The mineralized deposition enhances hydrophilicity and cell compatibility of mZIF-8/PLA membrane. mZIF-8/PLA membrane promotes up-regulation of osteogenesis and angiogenesis related factors in BMSCs. Moreover, it induces the polarization of macrophages towards the M2 phenotype and modulates the local immune microenvironment. After 4-weeks of implantation, the mZIF-8/PLA membrane successfully bridges critical bone defects and almost completely repairs the defect area after 12-weeks, while significantly improving the strength and vascularization of new bone. CONCLUSIONS: The mZIF-8/PLA membrane with dual osteoconductive and immunomodulatory abilities could pave new research paths for bone tissue engineering.

A sequential macrophage activation strategy for bone regeneration: A micro/nano strontium-releasing composite scaffold loaded with lipopolysaccharide.

Effective tissue repair relies on the orchestration of different macrophage phenotypes, both the M2 phenotype (promotes tissue repair) and M1 phenotype (pro-inflammatory) deserve attention. In this study, we propose a sequential immune activation strategy to mediate bone regeneration, by loading lipopolysaccharide (LPS) onto the surface of a strontium (Sr) ions -contained composite scaffold, which was fabricated by combining Sr-doped micro/nano-hydroxyapatite (HA) and dual degradable matrices of polycaprolactone (PCL) and poly (lactic-co-glycolic acid) (PLGA). Our strategy involves the sequential release of LPS to promote macrophage homing and induce the expression of the pro-inflammatory M1 phenotype, followed by the release of Sr ions to suppress inflammation. In vitro and in vivo experiments demonstrated that, the appropriate pro-inflammatory effects at the initial stage of implantation, along with the anti-inflammatory effects at the later stage, as well as the structural stability of the scaffolds conferred by the composition, can synergistically promote the regeneration and repair of bone defects.

Modulating macrophage phenotype for accelerated wound healing with chlorogenic acid-loaded nanocomposite hydrogel.

Wound healing involves distinct phases, including hemostasis, inflammation, proliferation, and remodeling, which is a complex and dynamic process. Conventional preparations often fail to meet multiple demands and provide prompt information about wound status. Here, a pH/ROS dual-responsive hydrogel (OHA-PP@Z-CA@EGF) was constructed based on oxidized hyaluronic acid (OHA), phenylboronic acid-grafted ε-polylysine (PP), chlorogenic acid (CA)-loaded ZIF-8 (Z-CA), and epidermal growth factor (EGF), which possesses intrinsic antibacterial, antioxidant, and angiogenic capacities. Due to the Schiff base and Phenylboronate ester bonds, the hydrogel exhibited excellent mechanical properties, strong adhesion, good biodegradability, high biocompatibility, stable rheological properties, and self-healing ability. Moreover, introducing Z-CA as an initiator and nanofiller led to the additional cross-linking of hydrogel through coordination bonds, which further improved the mechanical properties and antioxidant capabilities. Bleeding models of liver and tail amputations demonstrated rapid hemostatic properties of the hydrogel. Besides, the hydrogel regulated macrophage phenotypes via the NF-κB/JAK-STAT pathways, relieved oxidative stress, promoted cell migration and angiogenesis, and accelerated diabetic wound healing. The hydrogel also enabled real-time monitoring of the wound healing stages by colorimetric detection. This multifunctional hydrogel opens new avenues for the treatment and management of full-thickness diabetic wounds.

Effects of a Bioengineered Allogeneic Cellularized Construct (BACC) on Primary Human Macrophage Phenotype.

The mechanisms behind the pro-healing effects of multicellular, bioengineered allogeneic cellularized constructs (BACC) are not known. Macrophages are key regulators of every phase of the wound healing process and the primary cells that mediate the response to biomaterials. It is hypothesized that cells within the BACC modulate macrophage behavior, which may contribute to the mechanism by which BACC promotes healing. To probe the influence of cells within the BACC compared to effects of the underlying collagen substrate, primary human macrophages are cultured in direct or indirect contact with BACC or with the same collagen substrate used in the BACC manufacturing. Macrophage phenotype is characterized over time via multiplex gene expression, protein secretion, multidimensional flow cytometry, and functional assays with fibroblasts and endothelial cells. The BACC causes macrophages to exhibit a predominately reparative phenotype over time compared to relevant collagen substrate controls, with multiple subpopulations expressing both pro-inflammatory and reparative markers. Conditioned media from macrophage-BACC co-cultures causes distinct effects on fibroblast and endothelial cell proliferation, migration, and network formation. Given the critical role of the reparative macrophage phenotype in wound healing, these results suggest that modulation of macrophage phenotype may be a critical part of the mechanisms behind BACC's pro-healing effects.

SMYD3 activates the TCA cycle to promote M1-M2 conversion in macrophages.

BACKGROUND: SMYD3 refers to a histone lysine methyltransferase from the SMYD family, which acts as a gene transcriptional regulator chiefly through catalysis of the histone subunit 3 at lysine 4 trimethylation (H3K4me3). Great progress has been made that epigenetic modification plays a pivotal role in regulating macrophage polarization. However, the effects of the histone lysine methyltransferase SMYD3 on macrophage polarization and phenotypic switching are unclear. RESULTS: We found that LPS/IFN-γ-stimulated macrophages gradually transformed from M1 to M2 in the late stage, and SMYD3 played a key role in this process. As demonstrated by RNA-seq assessment, SMYD3 prominently activated a metabolic pathway known as TCA cycle inside macrophages during M1-M2 conversion. Besides, by modifying H3K4me3 histone, the target genes regulated by SMYD3 were identified via the ChIP-seq assessment, including citrate synthase (CS), succinate dehydrogenase complex subunit C (SDHC) and pyruvate carboxylase (PC). SMYD3 activated the transcriptional activities of the metabolic enzymes CS, SDHC and PC through H3K4me3 by causing the aggregation of citrate, an intramacrophage metabolite, and the depletion of succinate. And additionally, it facilitated the generation of ROS, as well as the expressions of genes associated with mitochondrial respiratory chain complexes. This increased ROS production ultimately induced mitophagy, triggering the M1 to M2 phenotype switch in the macrophages. CONCLUSIONS: Our study provides a detailed intrinsic mechanism in the macrophage phenotypic transition process, in short, SMYD3 promotes the M1-M2 conversion of macrophages by activating the TCA cycle through the simultaneous regulation of the transcriptional activities of the metabolic enzymes CS, SDHC and PC.

Transdermal Transfersome Nanogels Control Hypertrophic Scar Formation via Synergy of Macrophage Phenotype-Switching and Anti-Fibrosis Effect.

Hypertrophic scar (HS), which results from prolonged inflammation and excessive fibrosis in re-epithelialized wounds, is one of the most common clinical challenges. Consequently, sophisticated transdermal transfersome nanogels (TA/Fu-TS) are prepared to control HS formation by synergistically inhibiting inflammation and suppressing fibrosis. TA/Fu-TSs have unique structures comprising hydrophobic triamcinolone acetonide (TA) in lipid multilayers and hydrophilic 5-fluorouracil in aqueous cores, and perform satisfactorily with regard to transdermal co-delivery to macrophages and HS fibroblasts in emerging HS tissues. According to the in vitro/vivo results, TA/Fu-TSs not only promote macrophage phenotype-switching to inhibit inflammation by interleukin-related pathways, but also suppress fibrosis to remodel extracellular matrix by collagen-related pathways. Therefore, TA/Fu-TSs overcome prolonged inflammation and excessive fibrosis in emerging HS tissues, and provide an effective therapeutic strategy for controlling HS formation via their synergy of macrophage phenotype-switching and anti-fibrosis effect.

Tumor cell SPTBN1 inhibits M2 polarization of macrophages by suppressing CXCL1 expression.

Tumor-associated macrophages (TAMs) are the most abundant immune cells in the tumor microenvironment, and the M2-type TAMs can promote tumor growth, invasion and angiogenesis, and suppress antitumor immune responses. It has been reported that spectrin beta, non-erythrocytic 1 (SPTBN1) may inhibit the infiltration of macrophages in Sptbn1+/-  mouse liver, but whether tumor SPTBN1 affects TAMs polarization remains unclear. This study investigated the effect and mechanism of tumor cell SPTBN1 on polarization and migration of TAMs in hepatoma and breast cancer. By analyzing tumor immune databases, we found a negative correlation between SPTBN1 and abundance of macrophages and myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment. By reverse transcription-quantitative real-time PCR assays and cell migration assays, the migration and M2 polarization of macrophages were enhanced by the culture medium from hepatocellular carcinoma cell line PLC/PRF/5, SNU449, and breast cancer cell line MDA-MB-231 with SPTBN1 suppression, which could be reversed by CXCL1 neutralizing antibody MAB275. Meanwhile, the ability of migration and colony formation of PLC/PRF/5, SNU449, and MDA-MB-231 cells were promoted when coculture with M2 macrophages. We also found that SPTBN1 regulated CXCL1 through p65 by cytoplasmic-nuclear protein isolation experiments and ChIP-qPCR. Our data suggest that tumor cell SPTBN1 inhibits migration and M2-type polarization of TAMs by reducing the expression and secretion of CXCL1 via inhibiting p65 nuclear localization.

Tumor-associated macrophages in canine visceral hemangiosarcoma.

Canine hemangiosarcoma (HSA) is a highly malignant tumor derived from hematopoietic stem cells and commonly occurs in visceral organs or skin. Visceral HSAs are particularly aggressive and progress rapidly despite multimodal treatment. Tumor-associated macrophages (TAMs) play a central role in carcinogenesis, tumor progression, and metastasis in humans and murine models. In this retrospective study, we investigated the prevalence and phenotype of TAMs in privately owned, treatment-naïve dogs with naturally occurring HSA. We used CD204 as a general macrophage marker and CD206 as a marker for M2-polarized macrophages. Formalin-fixed paraffin-embedded tissues from HSAs in the spleen (n = 9), heart (n = 6), and other locations (n = 12) from 17 dogs were sectioned and immunohistochemically labeled with CD204 and CD206 antibodies. The mean number of log(CD204)- and log(CD206)-positive cells and the ratio of log(CD206/CD204)-positive cells were compared with normal surrounding tissues and between tumor locations. There were significantly more macrophages and M2 macrophages, and a higher ratio of M2 macrophages to total macrophages in tumor hot spots (P = .0002, P < .0001, and P = .0002, respectively) and in tumor tissues outside of hot spots (P = .009, P = .002, and P = .007, respectively) than in normal surrounding tissues. There were no significant differences between tumor locations, but there was a trend toward higher numbers of CD204-positive macrophages within the splenic tumors. There was no association between histological parameters or clinical stage and TAM numbers or phenotype. As in humans, TAMs in dogs with HSA have a predominantly M2-skewed phenotype. Dogs with HSA could serve as excellent models to evaluate new TAM-reprogramming therapies.

Epigenetic modification of TWIST1 in macrophages promotes hypertension-induced atherosclerotic plaque instability.

It is accepted that hypertension is a major, independent risk factor for atherosclerotic cardiovascular ischemic events, which are mainly attributed to the formation of unstable, vulnerable atherosclerotic lesions. But the mechanisms by which hypertension aggravates atherosclerosis (AS) through increased macrophage recruitment are unknown. It has been reported that TWIST1 can regulate the shear stress of blood flow in endothelial cells to promote the development of atherosclerosis, but the function of TWIST1 in macrophage recruitment during hypertension remains undefined. Here, the roles of TWIST1 in macrophage activation during N w -nitro-l-arginine-methyl ester (L-NAME; NO-synthase (NOS) inhibitor)-induced hypertension were investigated in ApoE-/- mice fed a high-fat diet (HFD) and RAW264.7 cells treated with oxidized low-density lipoprotein(ox-LDL). Oil Red O staining and hematoxylin and eosin staining were adopted to analyze atherosclerotic lesions and plaque instability. Chromatin immunoprecipitation (ChIP)-PCR was used to explore whether Lysine-specific histone demethylase 1A (LSD1/KDM1A) and Variegated suppressor 3-9 homolog 1 (SUV39H1) could regulate histone modification of the TWIST1 promoter. We reported that L-NAME increased the expression of TWIST1 in the aortic tissues of ApoE-/- mice fed a high-fat diet (HFD) and RAW264.7 cells treated with ox-LDL. TWIST1 accelerated the development of an unstable atherosclerotic phenotype by promoting macrophage activation, inflammatory factor secretion, macrophage polarization, and lipid phagocytosis. Moreover, we found that H3K9me2 and H3K9me3 in the TWIST1 promoter could be coregulated by LSD1 and SUV39H1, and this process was modulated by CK2α. Taken together, these results revealed that TWIST1 in macrophages is a critical factor that mediates foam cell formation and enhances atherosclerotic plaque vulnerability during hypertension, and targeting TWIST1 may be a promising new therapeutic approach for delaying the progression of AS in hypertension.

SEMA4D/VEGF surface enhances endothelialization by diminished-glycolysis-mediated M2-like macrophage polarization.

Cardiovascular disease remains the leading cause of death and morbidity worldwide. Inflammatory responses after percutaneous coronary intervention led to neoathrosclerosis and in-stent restenosis and thus increase the risk of adverse clinical outcomes. In this work, a metabolism reshaped surface is engineered, which combines the decreased glycolysis promoting, M2-like macrophage polarization, and rapid endothelialization property. Anionic heparin plays as a linker and mediates cationic SEMA4D and VEGF to graft electronically onto PLL surfaces. The system composed by anticoagulant heparin, immunoregulatory SEMA4D and angiogenic VEGF endows the scaffold with significant inhibition of platelets, fibrinogen and anti-thrombogenic properties, also noteworthy immunometabolism reprogram, anti-inflammation M2-like polarization and finally leading to rapid endothelializaiton performances. Our research indicates that the immunometabolism method can accurately reflect the immune state of modified surfaces. It is envisioned immunometabolism study will open an avenue to the surface engineering of vascular implants for better clinical outcomes.

Predominantly Pro-Inflammatory Phenotype with Mixed M1/M2 Polarization of Peripheral Blood Classical Monocytes and Monocyte-Derived Macrophages among Patients with Excessive Ethanol Intake.

Excessive alcohol consumption impairs the immune system, induces oxidative stress, and triggers the activation of peripheral blood (PB) monocytes, thereby contributing to alcoholic liver disease (ALD). We analyzed the M1/M2 phenotypes of circulating classical monocytes and macrophage-derived monocytes (MDMs) in excessive alcohol drinkers (EADs). PB samples from 20 EADs and 22 healthy controls were collected for isolation of CD14+ monocytes and short-term culture with LPS/IFNγ, IL4/IL13, or without stimulation. These conditions were also used to polarize MDMs into M1, M2, or M0 phenotypes. Cytokine production was assessed in the blood and culture supernatants. M1/M2-related markers were analyzed using mRNA expression and surface marker detection. Additionally, the miRNA profile of CD14+ monocytes was analyzed. PB samples from EADs exhibited increased levels of pro-inflammatory cytokines. Following short-term culture, unstimulated blood samples from EADs showed higher levels of soluble TNF-α and IL-8, whereas monocytes expressed increased levels of surface TNF-α and elevated mRNA expression of pro-inflammatory cytokines and inducible nitric oxide synthase. MDMs from EADs showed higher levels of TNF-α and CD206 surface markers and increased IL-10 production. LPS/IFNγ induced higher mRNA expression of Nrf2 only in the controls. miRNA analysis revealed a distinctive miRNA profile that is potentially associated with liver carcinogenesis and ALD through inflammation and oxidative stress. This study confirms the predominantly pro-inflammatory profile of PB monocytes among EADs and suggests immune exhaustion features in MDMs.

Macrophage Polarization Status Impacts Nanoceria Cellular Distribution but Not Its Biotransformation or Ferritin Effects.

The innate immune system is the first line of defense against external threats through the initiation and regulation of inflammation. Macrophage differentiation into functional phenotypes influences the fate of nanomaterials taken up by these immune cells. High-resolution electron microscopy was used to investigate the uptake, distribution, and biotransformation of nanoceria in human and murine M1 and M2 macrophages in unprecedented detail. We found that M1 and M2 macrophages internalize nanoceria differently. M1-type macrophages predominantly sequester nanoceria near the plasma membrane, whereas nanoceria are more uniformly distributed throughout M2 macrophage cytoplasm. In contrast, both macrophage phenotypes show identical nanoceria biotransformation to cerium phosphate nanoneedles and simultaneous nanoceria with ferritin co-precipitation within the cells. Ferritin biomineralization is a direct response to nanoparticle uptake inside both macrophage phenotypes. We also found that the same ferritin biomineralization mechanism occurs after the uptake of Ce-ions into polarized macrophages and into unpolarized human monocytes and murine RAW 264.7 cells. These findings emphasize the need for evaluating ferritin biomineralization in studies that involve the internalization of nano objects, ranging from particles to viruses to biomolecules, to gain greater mechanistic insights into the overall immune responses to nano objects.

Discovery of a novel small molecule with efficacy in protecting against inflammation in vitro and in vivo by enhancing macrophages activation.

Immune response and inflammation highly contribute to many metabolic syndromes such as inflammatory bowel disease (IBD), ageing and cancer with disruption of host metabolic homeostasis and the gut microbiome. Icariin-1 (GH01), a small-molecule flavonoid derived from Epimedium, has been shown to protect against systemic inflammation. However, the molecular mechanisms by which GH01 ameliorates ulcerative colitis via regulation of microbiota-mediated macrophages polarization remain elusive. In this study, we found that GH01 effectively ameliorated dextran sulfate sodium (DSS)-induced colitis symptoms in mice. Disruption of intestinal barrier function, commensal microbiota and its metabolites were also significantly restored by GH01 in a dose-dependent manner. Of note, we also found that GH01 enhanced phagocytic ability of macrophages and switched macrophage phenotype from M1 to M2 both in vitro and in vivo. Such macrophage polarization was highly associated with intestinal barrier integrity and the gut microbial community. Consequently, GH01 exhibited strong anti-inflammatory capacity by inhibiting TLR4 and NF-κB pathways and proinflammatory factors (IL-6). These findings suggested that GH01 might be a potential nutritional intervention strategy for IBD treatment with the gut microbial community-meditated macrophage as the therapeutic targets.

The miR-21-5p enriched in the apoptotic bodies of M2 macrophage-derived extracellular vesicles alleviates osteoarthritis by changing macrophage phenotype.

Macrophages (Mφs) play a crucial role in the pathological progression of osteoarthritis (OA) by regulating inflammation and tissue repair. Decreasing pro-inflammatory M1-Mφs and increasing anti-inflammatory M2-Mφs can alleviate OA-related inflammation and promote cartilage repair. Apoptosis is a natural process associated with tissue repair. A large number of apoptotic bodies (ABs), a type of extracellular vesicle, are produced during apoptosis, and this is associated with a reduction in inflammation. However, the functions of apoptotic bodies remain largely unknown. In this study, we investigated the role of M2-Mφs-derived apoptotic bodies (M2-ABs) in regulating the M1/M2 balance of macrophages in a mouse model of OA. Our data show that M2-ABs can be targeted for uptake by M1-Mφs, and this reprograms M1-to-M2 phenotypes within 24 h. The M2-ABs significantly ameliorated the severity of OA, alleviated the M1-mediated pro-inflammatory environment, and inhibited chondrocyte apoptosis in mice. RNA-seq revealed that M2-ABs were enriched with miR-21-5p, a microRNA that is negatively correlated with articular cartilage degeneration. Inhibiting the function of miR-21-5p in M1-Mφs significantly reduced M2-ABs-guided M1-to-M2 reprogramming following in vitro cell transfection. Together, these results suggest that M2-derived apoptotic bodies can prevent articular cartilage damage and improve gait abnormalities in OA mice by reversing the inflammatory response caused by M1 macrophages. The mechanism underlying these findings may be related to miR-21-5p-regulated inhibition of inflammatory factors. The application of M2-ABs may represent a novel cell therapy, and could provide a valuable strategy for the treatment of OA and/or chronic inflammation.

Heme-Induced Macrophage Phenotype Switching and Impaired Endogenous Opioid Homeostasis Correlate with Chronic Widespread Pain in HIV.

Chronic widespread pain (CWP) is associated with a high rate of disability and decreased quality of life in people with HIV-1 (PWH). We previously showed that PWH with CWP have increased hemolysis and elevated plasma levels of cell-free heme, which correlate with low endogenous opioid levels in leukocytes. Further, we demonstrated that cell-free heme impairs ß-endorphin synthesis/release from leukocytes. However, the cellular mechanisms by which heme dampens ß-endorphin production are inconclusive. The current hypothesis is that heme-dependent TLR4 activation and macrophage polarization to the M1 phenotype mediate this phenomenon. Our novel findings showed that PWH with CWP have elevated M1-specific macrophage chemokines (ENA-78, GRO-α, and IP-10) in plasma. In vitro, hemin-induced polarization of M0 and M2 macrophages to the M1 phenotype with low ß-endorphins was mitigated by treating cells with the TLR4 inhibitor, TAK-242. Similarly, in vivo phenylhydrazine hydrochloride (PHZ), an inducer of hemolysis, injected into C57Bl/6 mice increased the M1/M2 cell ratio and reduced ß-endorphin levels. However, treating these animals with the heme-scavenging protein hemopexin (Hx) or TAK-242 reduced the M1/M2 ratio and increased ß-endorphins. Furthermore, Hx attenuated heme-induced mechanical, heat, and cold hypersensitivity, while TAK-242 abrogated hypersensitivity to mechanical and heat stimuli. Overall, these results suggest that heme-mediated TLR4 activation and M1 polarization of macrophages correlate with impaired endogenous opioid homeostasis and hypersensitivity in people with HIV.

PTT/ PDT-induced microbial apoptosis and wound healing depend on immune activation and macrophage phenotype transformation.

Antibiotics show unsuccessful application in biofilm destruction, which induce chronic infections and emergence of antibiotic resistant bacteria. Photodynamic therapy (PDT) and photothermal therapy (PTT), as widely accepted antimicrobial tools of phototherapy, could effectively activate the immune system and promote the proliferation of wound tissue, thus becoming the most promising therapeutic strategy to replace antibiotics and avoid drug-resistant strains. However, there is no consensus on whether antibacterial and wound healing achieved by PDT/PTT depend not only on the cytotoxic effect of the treatment itself, but also on the activation of host immune system. In this study, CaSiO3-ClO2@PDA-ICG nanoparticles (CCPI NPs) were designed as PDT/PTT antimicrobial model material. With the comparison of healing effect between wide-type mice and severely immunodeficient (C-NKG) mice, the dependence of PDT/PTT-induced microbial apoptosis and wound healing on immune activation and macrophage phenotype transformation was explored and verified. Furthermore, the induced phenotypic transformation of macrophages during PDT/PTT treatment was demonstrated to play crucial role in the improvement of epithelial-mesenchymal transformation (EMT). In summary, this study represents great significance for further identifying the role of immune system activation in antibacterial phototherapy and developing new treatment strategies for biofilm-infected wound healing. STATEMENT OF SIGNIFICANCE: A PDT/PTT combination therapy model nanoparticle was established for biofilm-infected wounds. Both microbial apoptosis and wound healing achieved by PDT/PTT combination therapy were highly dependent on the activated immune system, especially the M2 macrophage phenotype. PDT/PTT could promote the polarization of monocytes to the phenotype of M2 macrophages, which promotes EMT behavior of the tissue at the edge of the wound through the secretion of TGF-ß1, thus accelerating wound healing.

Leishmaniasis: Immune Cells Crosstalk in Macrophage Polarization.

Leishmaniasis is a complex infectious parasitic disease caused by protozoa of the genus Leishmania, belonging to a group of neglected tropical diseases. It establishes significant global health challenges, particularly in socio-economically disadvantaged regions. Macrophages, as innate immune cells, play a crucial role in initiating the inflammatory response against the pathogens responsible for this disease. Macrophage polarization, the process of differentiating macrophages into pro-inflammatory (M1) or anti-inflammatory (M2) phenotypes, is essential for the immune response in leishmaniasis. The M1 phenotype is associated with resistance to Leishmania infection, while the M2 phenotype is predominant in susceptible environments. Notably, various immune cells, including T cells, play a significant role in modulating macrophage polarization by releasing cytokines that influence macrophage maturation and function. Furthermore, other immune cells can also impact macrophage polarization in a T-cell-independent manner. Therefore, this review comprehensively examines macrophage polarization's role in leishmaniasis and other immune cells' potential involvement in this intricate process.

Biologic Mechanisms of Macrophage Phenotypes Responding to Infection and the Novel Therapies to Moderate Inflammation.

Pro-inflammatory and anti-inflammatory types are the main phenotypes of the macrophage, which are commonly notified as M1 and M2, respectively. The alteration of macrophage phenotypes and the progression of inflammation are intimately associated; both phenotypes usually coexist throughout the whole inflammation stage, involving the transduction of intracellular signals and the secretion of extracellular cytokines. This paper aims to address the interaction of macrophages and surrounding cells and tissues with inflammation-related diseases and clarify the crosstalk of signal pathways relevant to the phenotypic metamorphosis of macrophages. On these bases, some novel therapeutic methods are proposed for regulating inflammation through monitoring the transition of macrophage phenotypes so as to prevent the negative effects of antibiotic drugs utilized in the long term in the clinic. This information will be quite beneficial for the diagnosis and treatment of inflammation-related diseases like pneumonia and other disorders involving macrophages.

miR-126 promotes M1 to M2 macrophage phenotype switching via VEGFA and KLF4.

Background: Macrophage polarization and microRNA play crucial roles in the development of atherosclerosis (AS). The M1 macrophage phenotype contributes to the formation of plaques, while the M2 macrophage phenotype resolves inflammation and promotes tissue repair. MiR-126 has been found to play a role in regulating macrophage polarization in the context of AS. However, the exact mechanism of miR-126 requires further research. Methods: The foam cell model was established by stimulating THP-1 with oxidized low-density lipoprotein (ox-LDL). We transfected foam cells with miR-126 mimic and its negative control. The transfection of miR-126 was implemented by riboFECT CP transfection kit. The levels of miR-126 and M1/M2 associated genes in foam cells were quantified using reverse transcription-quantitative PCR (RT-qPCR). Additionally, the expressions of CD86+ and CD206+ cells in foam cells were determined by flow cytometry. Western blotting and RT-qPCR were used to determine the protein and mRNA levels of the vascular endothelial growth factor A (VEGFA) and the transcriptional regulator Krüppel-like factor 4 (KLF4), respectively. Additionally, we detected endothelial cell migration after co-culturing endothelial cells and macrophages. MG-132 was used to indirectly activate the expression of VEGFA, and the expression of KLF4 was also evaluated. Results: The activation of apoptosis and production of foam cells were boosted by the addition of ox-LDL. We transfected foam cells with miR-126 mimic and its negative control and observed that miR-126 greatly suppressed foam cell development and inhibited phagocytosis. Moreover, it caused pro-inflammatory M1 macrophages to switch to the anti-inflammatory M2 phenotype. This was reflected by the increase in anti-inflammatory gene expression and the decrease in pro-inflammatory gene expression. Additionally, miR-126 dramatically decreased the expressions of VEGFA and KLF4. The protein-protein interaction network analysis showed a significantly high correlation between miR-126, VEGFA, and KLF4. MiR-126 may also promote EC migration by activating macrophage PPAR γ expression and effectively suppressing macrophage inflammation. MG-132 indirectly activated the expression of VEGFA, and the expression of KLF4 also significantly increased, which indicates a direct or indirect relationship between VEGFA and KLF4. Conclusion: Our study shows that miR-126 can reverse ox-LDL-mediated phagocytosis and apoptosis in macrophages. Consequently, the potential role of miR-126 was manifested in regulating macrophage function and promoting vascular endothelial migration.