Multistability in Macrophage Activation Pathways and Metabolic Implications

Infection‑associated bile acid disturbance contributes to macrophage activation in patients with cirrhosis

Cirrhosis impairs macrophage function and disrupts bile acid homeostasis. Although bile acids affect macrophage function in patients with sepsis, whether and how the bile acid profile is changed by infection in patients with cirrhosis to modulate macrophage function remains unclear. The present study aimed to investigate the changes in the bile acid profile of patients with cirrhosis and infection and their effects on macrophage function. Serum was collected from 20 healthy subjects, 18 patients with cirrhosis and 39 patients with cirrhosis and infection. Bile acid profiles were detected using high‑performance liquid chromatography‑triple time‑of‑flight mass spectrometer. The association between bile acid changes and infection was analysed using receiver operating characteristic (ROC) curves. Infection‑altered bile acids were used in combination with lipopolysaccharides (LPS) to stimulate RAW264.7/THP‑1 cells in vitro. The migratory capacity was evaluated using wound healing and Transwell migration assays. The expression of Arg‑1, iNOS, IκBα, phosphorylated (p‑)IκBα and p65 was examined with western blotting and immunofluorescence, Tnfα, Il1b and Il6 mRNA was examined with RT‑qPCR, and CD86, CD163 and phagocytosis was measured with flow cytometry. The ROC curves showed that decreased hyodeoxycholic acid (HDCA) and deoxycholic acid (DCA) levels were associated with infection. HDCA or DCA combined with LPS enhanced the phagocytic and migratory ability of macrophages, accompanied by upregulation of iNOS and CD86 protein expression as well as Tnfα, Il1b, and Il6 mRNA expression. However, neither HDCA nor DCA alone showed an effect on these phenotypes. In addition, DCA and HDCA acted synergistically with LPS to increase the expression of p‑IκBα and the intranuclear migration of p65. Infection changed the bile acid profile in patients with cirrhosis, among which the reduction of DCA and HDCA associated most strongly with infection. HDCA and DCA enhanced the sensitivity of macrophage function loss to LPS stimulation. These findings suggested a potential role for monitoring the bile acid profile that could help manage patients with cirrhosis and infection.

Acute neuroinflammation promotes a metabolic shift that alters extracellular vesicle cargo in the mouse brain cortex

Neuroinflammation is initiated through microglial activation and cytokine release which can be induced through lipopolysaccharide treatment (LPS) leading to a transcriptional cascade culminating in the differential expression of target proteins. These differentially expressed proteins can then be packaged into extracellular vesicles (EVs), a form of cellular communication, further propagating the neuroinflammatory response over long distances. Despite this, the EV proteome in the brain, following LPS treatment, has not been investigated. Brain tissue and brain derived EVs (BDEVs) isolated from the cortex of LPS-treated mice underwent thorough characterisation to meet the minimal information for studies of extracellular vesicles guidelines before undergoing mass spectrometry analysis to identify the differentially expressed proteins. Fourteen differentially expressed proteins were identified in the LPS brain tissue samples compared to the controls and 57 were identified in the BDEVs isolated from the LPS treated mice compared to the controls. This included proteins associated with the initiation of the inflammatory response, epigenetic regulation, and metabolism. These results allude to a potential link between small EV cargo and early inflammatory signalling.

Reyanning mixture inhibits M1 macrophage polarization through the glycogen synthesis pathway to improve lipopolysaccharide-induced acute lung injury

ETHNOPHARMACOLOGICAL RELEVANCE

Reyanning (RYN) mixture is a traditional Chinese medicine composed of Taraxacum, Polygonum cuspidatum, Scutellariae Barbatae and Patrinia villosa and is used for the treatment of acute respiratory system diseases with significant clinical efficacy.

AIM OF THE STUDY

Acute lung injury (ALI) is a common clinical disease characterized by acute respiratory failure. This study was conducted to evaluate the therapeutic effects of RYN on ALI and to explore its mechanism of action.

MATERIALS AND METHODS

Ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to analyze the chemical components of RYN. 7.5 mg/kg LPS was administered to induce ALI in rats. RYN was administered by gavage at doses of 2 ml/kg, 4 ml/kg or 8 ml/kg every 8 h for a total of 6 doses. Observations included lung histomorphology, lung wet/dry (W/D) weight ratio, lung permeability index (LPI), HE staining, Wright-Giemsa staining. ELISA was performed to detect the levels of TNF-α, IL-6, IL-10, Arg-1,UDPG. Immunohistochemical staining detected IL-6, F4/80 expression. ROS, MDA, SOD, GSH/GSSG were detected in liver tissues. Multiple omics techniques were used to predict the potential mechanism of action of RYN, which was verified by in vivo closure experiments. Immunofluorescence staining detected the co-expression of CD86 and CD206, CD86 and P2Y14, CD86 and UGP2 in liver tissues. qRT-PCR detected the mRNA levels of UGP2, P2Y14 and STAT1, and immunoblotting detected the protein expression of UGP2, P2Y14, STAT1, p-STAT1.

RESULTS

RYN was detected to contain 1366 metabolites, some of the metabolites with high levels have anti-inflammatory, antibacterial, antiviral and antioxidant properties. RYN (2, 4, and 8 ml/kg) exerted dose-dependent therapeutic effects on the ALI rats, by reducing inflammatory cell infiltration and oxidative stress damage, inhibiting CD86 expression, decreasing TNF-α and IL-6 levels, and increasing IL-10 and Arg-1 levels. Transcriptomics and proteomics showed that glucose metabolism provided the pathway for the anti-ALI properties of RYN and that RYN inhibited lung glycogen production and distribution. Immunofluorescence co-staining showed that RYN inhibited CD86 and UGP2 expressions. In vivo blocking experiments revealed that blocking glycogen synthesis reduced UDPG content, inhibited P2Y14 and CD86 expressions, decreased P2Y14 and STAT1 mRNA and protein expressions, reduced STAT1 protein phosphorylation expression, and had the same therapeutic effect as RYN.

CONCLUSION

RYN inhibits M1 macrophage polarization to alleviate ALI. Blocking glycogen synthesis and inhibiting the UDPG/P2Y14/STAT1 signaling pathway may be its molecular mechanism.

ZeXieYin formula alleviates atherosclerosis by inhibiting the MAPK/NF-κB signaling pathway in APOE-/- mice to attenuate vascular inflammation and increase plaque stability

ETHNOPHARMACOLOGICAL RELEVANCE

Zexieyin formula (ZXYF), a traditional Chinese herbal formula recorded in the Huangdi Neijing to have efficacy in relieving spleen dampness and heat accumulation syndrome, which is also the key pathogenesis of atherosclerosis (AS). The efficacy has demonstrated by our previous studies. However, the intrinsic mechanism of ZXYF for treating vascular inflammation and the effect of inflammatory response on plaque are not known. Currently, plaque stabilization is crucial for the prognosis of AS.

AIM OF THE STUDY

Our study mainly focused on the therapeutic effects of ZXYF on high-fat diet (HFD)-induced vascular inflammation and vulnerable plaques (VP) in mice and explored its underlying mechanism.

METHODS AND MATERIALS

Male apolipoprotein E knockout (APOE-/-) mice were fed HFD for 8 weeks to establish a VP model. During this period, the mice were also administered ZXYF, while atorvastatin (ATO) was used as a positive control. Aortic plaque area and morphology were detected by oil red staining and HE staining. Aortic plaque collagen content was detected by Masson staining. M1/M2 type macrophages were detected using immunofluorescence (IF). The study analyzed the levels of inflammation-related cytokines (IL-1β, IL-10, IL-6), MAPK/NF-κB pathway proteins, and NLRP3 inflammasomes (NLRP3, Caspase-1) using Western blot. Additionally, the levels of matrix metalloproteinase (MMP)-2 and MMP-9 and α-smooth muscle actin (α-SMA) in the aorta were analyzed using immunohistochemistry (IHC). The plaque instability index was calculated for each group using the vulnerable plaque formula.

RESULTS

In this study, APOE-/- mice were fed high-fat diet for 8 weeks. The results of oil-red and HE staining indicated a significant increase in the aortic plaque area of the mice, which exhibited a typical VP phenotype. ZXYF and ATO significantly improved AS plaques and prevented plaque rupture. HFD exacerbated vascular inflammation, stimulated macrophage conversion to M1-type through the MAPK/NF-κB signaling pathway, and released pro-inflammatory factors such as interleukin (IL)-1β, IL-1α, and IL-6. These factors activated NLRP3 inflammasome, leading to cellular death. However, ZXYF could reverse this trend and promote the conversion of macrophages to the anti-inflammatory M2 type. The anti-inflammatory effect of ATO was not significant. Moreover, HFD promoted the release of MMP-2 and MMP-9 from macrophages, which degraded plaque collagen, and induced a decrease in plaque SMC content, resulting in a thinning of the plaque fibrous cap. In contrast, ZXYF inhibited the decomposition of plaque collagen and increased the content of plaque smooth muscle cells (SMC) by reducing macrophage secretion of MMPs, thereby stabilizing plaques. Although ATO could reverse the decrease in plaque collagen and SMC content, its effect on MMPs was not significant. Finally, we calculated the vulnerability index to assess the overall risk of the plaque vulnerability phenotype. In line with these findings, ZXYF and ATO were able to effectively reverse the increase in the vulnerability index caused by HFD and lower the risk of adverse cardiovascular events.

CONCLUSION

Our results suggested that ZXYF could reduce inflammation and increase plaque stability by inhibiting the MAPK/NF-κB signaling pathway, which provided a theoretical basis for clinical application and subsequent research.

Phase 1 dose expansion and biomarker study assessing first-in-class tumor microenvironment modulator VT1021 in patients with advanced solid tumors

BACKGROUND

Preclinical studies have demonstrated that VT1021, a first-in-class therapeutic agent, inhibits tumor growth via stimulation of thrombospondin-1 (TSP-1) and reprograms the tumor microenvironment. We recently reported data from the dose escalation part of a phase I study of VT1021 in solid tumors. Here, we report findings from the dose expansion phase of the same study.

METHODS

We analyzed the safety and tolerability, clinical response, and biomarker profile of VT1021 in the expansion portion of the phase I study (NCT03364400). Safety/tolerability is determined by adverse events related to the treatment. Clinical response is determined by RECIST v1.1 and iRECIST. Biomarkers are measured by multiplexed ion beam imaging and enzyme-linked immunoassay (ELISA).

RESULTS

First, we report the safety and tolerability data as the primary outcome of this study. Adverse events (AE) suspected to be related to the study treatment (RTEAEs) are mostly grade 1-2. There are no grade 4 or 5 adverse events. VT1021 is safe and well tolerated in patients with solid tumors in this study. We report clinical responses as a secondary efficacy outcome. VT1021 demonstrates promising single-agent clinical activity in recurrent GBM (rGBM) in this study. Among 22 patients with rGBM, the overall disease control rate (DCR) is 45% (95% confidence interval, 0.24-0.67). Finally, we report the exploratory outcomes of this study. We show the clinical confirmation of TSP-1 induction and TME remodeling by VT1021. Our biomarker analysis identifies several plasmatic cytokines as potential biomarkers for future clinical studies.

CONCLUSIONS

VT1021 is safe and well-tolerated in patients with solid tumors in a phase I expansion study. VT1021 has advanced to a phase II/III clinical study in glioblastoma (NCT03970447).

Knockdown of trem2 promotes proinflammatory microglia and inhibits glioma progression via the JAK2/STAT3 and NF-κB pathways

BACKGROUND

In the tumor immune microenvironment (TIME), triggering receptor expressed on myeloid cells 2 (trem2) is widely considered to be a crucial molecule on tumor-associated macrophages(TAMs). Multiple studies have shown that trem2 may function as an immune checkpoint in various malignant tumors, mediating tumor immune evasion. However, its specific molecular mechanisms, especially in glioma, remain elusive.

METHODS

Lentivirus was transfected to establish cells with stable knockdown of trem2. A Transwell system was used for segregated coculture of glioma cells and microglia. Western blotting, quantitative real-time polymerase chain reaction (qRT‒PCR), and immunofluorescence (IF) were used to measure the expression levels of target proteins. The proliferation, invasion, and migration of cells were detected by colony formation, cell counting kit-8 (CCK8), 5-ethynyl-2'-deoxyuridine (EdU) and transwell assays. The cell cycle, apoptosis rate and reactive oxygen species (ROS) level of cells were assessed using flow cytometry assays. The comet assay and tube formation assay were used to detect DNA damage in glioma cells and angiogenesis activity, respectively. Gl261 cell lines and C57BL/6 mice were used to construct the glioma orthotopic transplantation tumor model.

RESULTS

Trem2 was highly overexpressed in glioma TAMs. Knocking down trem2 in microglia suppressed the growth and angiogenesis activity of glioma cells in vivo and in vitro. Mechanistically, knockdown of trem2 in microglia promoted proinflammatory microglia and inhibited anti-inflammatory microglia by activating jak2/stat1 and inhibiting the NF-κB p50 signaling pathway. The proinflammatory microglia produced high concentrations of nitric oxide (NO) and high levels of the proinflammatory cytokines TNF-α, IL-6, and IL-1β, and caused further DNA damage and promoted the apoptosis rate of tumor cells.

CONCLUSIONS

Our findings revealed that trem2 in microglia plays a significant role in the TIME of gliomas. Knockdown of trem2 in microglia might help to improve the efficiency of inhibiting glioma growth and delaying tumor progression and provide new ideas for further treatment of glioma.

A novel blood-based bioassay to monitor adiponectin signaling

The diverse beneficial effects of adiponectin-receptor signaling, including its impact on the regulation of inflammatory processes in vivo, have resulted in development of adiponectin receptor agonists as a treatment for metabolic disorders. However, there are no established non-invasive bioassays for detection of adiponectin target engagement in humans or animal models. Here, we designed an assay using small amounts of blood to assess adiponectin action. Specifically, we tested effects of the small 10-amino acid peptide adiponectin receptor agonist, ALY688, in a sublethal LPS endotoxemia model in mice. LPS-induced pro-inflammatory cytokine levels in serum were significantly reduced in mice treated with ALY688, assessed via multiplex ELISA in flow cytometry. Furthermore, ALY688 alone significantly induced TGF-β release in serum 1 h after treatment and was elevated for up to 24 h. Additionally, using a flow-cytometry panel for detection of changes in circulating immune cell phenotypes, we observed a significant increase in absolute T cell counts in mice after ALY688 treatment. To assess changes in intracellular signaling effectors downstream of adiponectin, phospho-flow cytometry was conducted. There was a significant increase in phosphorylation of AMPK and p38-MAPK in mice after ALY688 treatment. We then used human donor immune cells (PBMCs) treated with ALY688 ex vivo and observed elevation of AMPK and p38-MAPK phosphorylation from baseline in response to ALY688. Together, these results indicate we can detect adiponectin action on immune cells in vivo by assessing adiponectin signaling pathway for AMPK and p38-MAPK, as well as pro-inflammatory cytokine levels. This new approach provides a blood-based bioassay for screening adiponectin action.

Metabolic Adaptations and Functional Activity of Macrophages in Homeostasis and Inflammation

In recent years, the role of cellular metabolism in immunity has come into the focus of many studies. These processes form a basis for the maintenance of tissue integrity and homeostasis, as well as represent an integral part of the immune response, in particular, inflammation. Metabolic adaptations not only ensure energy supply for immune response, but also affect the functions of immune cells by controlling transcriptional and post-transcriptional programs. Studying the immune cell metabolism facilitates the search for new treatment approaches, especially for metabolic disorders. Macrophages, innate immune cells, are characterized by a high functional plasticity and play a key role in homeostasis and inflammation. Depending on the phenotype and origin, they can either perform various regulatory functions or promote inflammation state, thus exacerbating the pathological condition. Furthermore, their adaptations to the tissue-specific microenvironment influence the intensity and type of immune response. The review examines the effect of metabolic reprogramming in macrophages on the functional activity of these cells and their polarization. The role of immunometabolic adaptations of myeloid cells in tissue homeostasis and in various pathological processes in the context of inflammatory and metabolic diseases is specifically discussed. Finally, modulation of the macrophage metabolism-related mechanisms reviewed as a potential therapeutic approach.

Melatonin improves influenza virus infection-induced acute exacerbation of COPD by suppressing macrophage M1 polarization and apoptosis

BACKGROUND

Influenza A viruses (IAV) are extremely common respiratory viruses for the acute exacerbation of chronic obstructive pulmonary disease (AECOPD), in which IAV infection may further evoke abnormal macrophage polarization, amplify cytokine storms. Melatonin exerts potential effects of anti-inflammation and anti-IAV infection, while its effects on IAV infection-induced AECOPD are poorly understood.

METHODS

COPD mice models were established through cigarette smoke exposure for consecutive 24 weeks, evaluated by the detection of lung function. AECOPD mice models were established through the intratracheal atomization of influenza A/H3N2 stocks in COPD mice, and were injected intraperitoneally with melatonin (Mel). Then, The polarization of alveolar macrophages (AMs) was assayed by flow cytometry of bronchoalveolar lavage (BAL) cells. In vitro, the effects of melatonin on macrophage polarization were analyzed in IAV-infected Cigarette smoking extract (CSE)-stimulated Raw264.7 macrophages. Moreover, the roles of the melatonin receptors (MTs) in regulating macrophage polarization and apoptosis were determined using MTs antagonist luzindole.

RESULTS

The present results demonstrated that IAV/H3N2 infection deteriorated lung function (reduced FEV20,50/FVC), exacerbated lung damages in COPD mice with higher dual polarization of AMs. Melatonin therapy improved airflow limitation and lung damages of AECOPD mice by decreasing IAV nucleoprotein (IAV-NP) protein levels and the M1 polarization of pulmonary macrophages. Furthermore, in CSE-stimulated Raw264.7 cells, IAV infection further promoted the dual polarization of macrophages accompanied with decreased MT1 expression. Melatonin decreased STAT1 phosphorylation, the levels of M1 markers and IAV-NP via MTs reflected by the addition of luzindole. Recombinant IL-1β attenuated the inhibitory effects of melatonin on IAV infection and STAT1-driven M1 polarization, while its converting enzyme inhibitor VX765 potentiated the inhibitory effects of melatonin on them. Moreover, melatonin inhibited IAV infection-induced apoptosis by suppressing IL-1β/STAT1 signaling via MTs.

CONCLUSIONS

These findings suggested that melatonin inhibited IAV infection, improved lung function and lung damages of AECOPD via suppressing IL-1β/STAT1-driven macrophage M1 polarization and apoptosis in a MTs-dependent manner. Melatonin may be considered as a potential therapeutic agent for influenza virus infection-induced AECOPD.

D-Mannose promotes recovery from experimental colitis by inducing AMPK phosphorylation to stimulate epithelial repair

Delayed mucosal healing and impaired intestinal epithelial barrier function have been implicated in the pathogenesis of ulcerative colitis (UC). Accordingly, restoration of epithelial barrier function as a means to reshape mucosal homeostasis represents an important strategy for use in the treatment of UC. In this study, we examined the role and mechanisms of D-mannose in the recovery of colitis as assessed in both animal and cell models. We found that D-mannose ameliorated inflammation, promoted mucosal healing in the colon and therefore was able to induce the recovery of UC. Furthermore, D-mannose increased the expression of tight junction (TJ) proteins and reduced the intestinal permeability during the recovery of colitis. Moreover, D-mannose inhibited M1 macrophage polarization and promoted M2 macrophage polarization via inducing AMPK phosphorylation while reducing mTOR phosphorylation in both models. In addition, increased TJ protein expression and decreased paracellular permeability were observed in NCM460 cells when incubated with the supernatants of D-mannose-treated RAW264.7 cells, suggesting that M1/M2 polarization induced by D-mannose modulates the expression of TJ proteins. Further study showed that D-mannose significantly upregulated the expression of TJ proteins in DSS-treated NCM460 cells by inducing AMPK phosphorylation, indicating a direct protective effect on epithelial cells. Finally, the protective effects of D-mannose were significantly abrogated by the presence of compound C, an AMPK inhibitor. Taken together, our data indicate that D-mannose can alleviate inflammation and foster epithelial restitution in UC recovery by inducing the TJ protein expression, which are achieved by inducing AMPK phosphorylation in the epithelium and/or macrophages.

The role of AMPK in macrophage metabolism, function and polarisation

AMP-activated protein kinase (AMPK) is a ubiquitous sensor of energy and nutritional status in eukaryotic cells. It plays a key role in regulating cellular energy homeostasis and multiple aspects of cell metabolism. During macrophage polarisation, AMPK not only guides the metabolic programming of macrophages, but also counter-regulates the inflammatory function of macrophages and promotes their polarisation toward the anti-inflammatory phenotype. AMPK is located at the intersection of macrophage metabolism and inflammation. The metabolic characteristics of macrophages are closely related to immune-related diseases, infectious diseases, cancer progression and immunotherapy. This review discusses the structure of AMPK and its role in the metabolism, function and polarisation of macrophages. In addition, it summarises the important role of the AMPK pathway and AMPK activators in the development of macrophage-related diseases.

Phenylalanine diminishes M1 macrophage inflammation

Emerging evidence suggests that amino acids dictate the effector functions of immune cells; however, whether and how phenylalanine (Phe) orchestrates the polarization of macrophages is not understood. Here, we determined that Phe attenuated lipopolysaccharide (LPS) and P. multocida serotype A strain CQ2 (PmCQ2) infection-induced inflammation in vivo. Furthermore, we demonstrated that Phe inhibited the production of interleukin (IL)-1β and tumor necrosis factor (TNF)-α in proinflammatory (M1) macrophages. Phe reprogrammed the transcriptomic and metabolic profiles and enhanced oxidative phosphorylation in M1 macrophages, which reduced the activation of caspase-1. Notably, the valine-succinyl-CoA axis played a critical role in Phe-mediated inhibition of IL-1β production in M1 macrophages. Taken together, our findings suggest that manipulating the valine-succinyl-CoA axis provides a potential target for preventing and/or treating macrophage-related diseases.

Oral Administration of Platinum Nanoparticles with SOD/CAT Cascade Catalytic Activity to Alleviate Ulcerative Colitis

Ulcerative colitis (UC) is a refractory chronic inflammatory disease involving the colon and rectum, falling under the category of inflammatory bowel disease (IBD). The accumulation of reactive oxygen species (ROS) in local tissues has been identified as a crucial contributor to the escalation of inflammatory responses. Therefore, eliminating ROS in the inflamed colon is a promising approach to treating UC. Nanomaterials with intrinsic enzyme-like activities (nanozymes) have shown significant therapeutic potential in UC. In this study, we found that platinum nanoparticles (Pt NPs) exhibited remarkable superoxide dismutase (SOD) and catalase (CAT) cascade catalytic activities, as well as effective hydroxyl radical (•OH) scavenging ability. The in vitro experiments showed that Pt NPs could eliminate excessive ROS to protect cells against oxidative stress. In the colitis model, oral administration of Pt NPs (loaded in chitosan/alginate hydrogel) could significantly alleviate UC, including reducing the colon length, the damaged epithelium, and the infiltration of inflammatory cells. Without appreciable systemic toxicity, Pt NPs represent a novel therapeutic approach to UC and are expected to achieve long-term inflammatory remission.

Macrophage metabolism, phenotype, function, and therapy in hepatocellular carcinoma (HCC)

The pivotal role of the tumor microenvironment (TME) in the initiation and advancement of hepatocellular carcinoma (HCC) is widely acknowledged, as it fosters the proliferation and metastasis of HCC cells. Within the intricate TME of HCC, tumor-associated macrophages (TAMs) represent a significant constituent of non-malignant cells. TAMs engage in direct communication with cancer cells in HCC, while also exerting influence on other immune cells to adopt a tumor-supportive phenotype that facilitates tumor progression. Among the multifaceted mechanisms at play, the metabolic reprogramming of both tumor cells and macrophages leads to phenotypic alterations and functional modifications in macrophages. This comprehensive review elucidates the intricate interplay between cellular metabolism and macrophage phenotype/polarization, while also providing an overview of the associated signaling molecules and potential therapeutic strategies for HCC.

Mycobacterium tuberculosis Mce2D protein blocks M1 polarization in macrophages by inhibiting the ERK signaling pathway

Macrophages play a pivotal role in controlling Mycobacterium infection, and the pathogen thrives in the event of immune evasion and immunosuppression of macrophages. Mammalian cell entry proteins (Mce) are required for Mycobacterium tuberculosis (M. tb) growth and the host cell's initial phagocytosis and cytokine response. Mce2D protein is one of a family of proteins that infect M. tb; however, the function and mechanism of action remain unclear. In this study, we constructed the Mce2D knockout strain using Mycobacterium smegmatis to study the function of Mce2D in the infection of macrophages. The results indicated that compared to the knockout strain, the release of proinflammatory cytokines (TNF-α and IL-1β) reduced when WT strain infected the macrophages. Moreover, Mce2D boosted the metabolism of oxidized fatty acids, increased the energy supply of TCA, and lowered the glycolysis of glucose in macrophages after bacterial infection, all of which prevented the polarization of macrophages to M1, which was driven by the fact that Mce2D blocked ERK2 phosphorylation by interacting with ERK2 through its DEF motif. This, in turn, promoted nuclear translocation of HIF-1α, allowing signal accumulation, which increased the HIF-1α transcription levels. Finally, the mouse infection experiment showed that Mce2D caused blockage of M1 polarization of alveolar macrophages, resulting in reduced bactericidal activity and antigen presentation, weakening Th1 cell-mediated immune response and helping bacteria escape the immune system. Our results reveal that Mce2D causes immune escape by blocking M1 polarization in macrophages, providing potential targets for the rational design of therapies against M. tb infection.

Cell state transition analysis identifies interventions that improve control of Mycobacterium tuberculosis infection by susceptible macrophages

Understanding cell state transitions and purposefully controlling them to improve therapies is a longstanding challenge in biological research and medicine. Here, we identify a transcriptional signature that distinguishes activated macrophages from the tuberculosis (TB) susceptible and resistant mice. We then apply the cSTAR (cell state transition assessment and regulation) approach to data from screening-by-RNA sequencing to identify chemical perturbations that shift the transcriptional state of tumor necrosis factor (TNF)-activated TB-susceptible macrophages toward that of TB-resistant cells, i.e., prevents their aberrant activation without suppressing beneficial TNF responses. Last, we demonstrate that the compounds identified with this approach enhance the resistance of the TB-susceptible mouse macrophages to virulent Mycobacterium tuberculosis.

The role of peroxisome proliferator-activated receptor γ in lipid metabolism and inflammation in atherosclerosis

Cardiovascular disease events are the result of functional and structural abnormalities in the arteries and heart. Atherosclerosis is the main cause and pathological basis of cardiovascular diseases. Atherosclerosis is a multifactorial disease associated with dyslipidemia, inflammation, and oxidative stress, among which dyslipidemia and chronic inflammation occur in all processes. Under the influence of lipoproteins, the arterial intima causes inflammation, necrosis, fibrosis, and calcification, leading to plaque formation in specific parts of the artery, which further develops into plaque rupture and secondary thrombosis. Foam cell formation from macrophages is an early event in the development of atherosclerosis. Lipid uptake causes a vascular inflammatory response, and persistent inflammatory infiltration in the lesion area further promotes the development of the disease. Inhibition of macrophage differentiation into foam cell and reduction of the level of proinflammatory factors in macrophages can effectively alleviate the occurrence and development of atherosclerosis. Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated nuclear receptor that plays an important antiatherosclerotic role by regulating triglyceride metabolism, lipid uptake, cholesterol efflux, macrophage polarity, and inhibiting inflammatory signaling pathways. In addition, PPARγ shifts its binding to ligands and co-activators or co-repressors of transcription of target genes through posttranslational modification, thereby affecting the regulation of its downstream target genes. Many ligand agonists have also been developed targeting PPARγ. In this review, we summarized the role of PPARγ in lipid metabolism and inflammation in development of atherosclerosis, the posttranslational regulatory mechanism of PPARγ, and further discusses the value of PPARγ as an antiatherosclerosis target.

de la Fuente M, Simarro M. The mitochondrial succinate dehydrogenase complex controls the STAT3-IL-10 pathway in inflammatory macrophages

The functions of macrophages are tightly regulated by their metabolic state. However, the role of the mitochondrial electron transport chain (ETC) in macrophage functions remains understudied. Here, we provide evidence that the succinate dehydrogenase (SDH)/complex II (CII) is required for respiration and plays a role in controlling effector responses in macrophages. We find that the absence of the catalytic subunits Sdha and Sdhb in macrophages impairs their ability to effectively stabilize HIF-1α and produce the pro-inflammatory cytokine IL-1β in response to LPS stimulation. We also arrive at the novel result that both subunits are essential for the LPS-driven production of IL-10, a potent negative feedback regulator of the macrophage inflammatory response. This phenomenon is explained by the fact that the absence of Sdha and Sdhb leads to the inhibition of Stat3 tyrosine phosphorylation, caused partially by the excessive accumulation of mitochondrial reactive oxygen species (mitoROS) in the knockout cells.

Integration of Metabolomic and Transcriptomic Provides Insights into Anti-Inflammatory Response to trans-10-Hydroxy-2-decenoic Acid on LPS-Stimulated RAW 264.7 Cells

Trans-10-hydroxy-2-decenoic acid (10-HDA) is a unique fatty acid found in royal jelly that possesses potential health benefits such as anti-inflammatory. However, further research is needed to fully understand its mechanisms of action and therapeutic potential for inflammation-associated diseases. In this present study, liquid chromatography-tandem mass spectrometry (LC-MS/MS) and RNA-seq analyses were conducted to comprehensively analyze the in vitro anti-inflammatory effects of 10-HDA on lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Our results demonstrated that 128 differentially expressed metabolites and 1721 differentially expressed genes were identified in the 10-HDA-treated groups compared to the LPS groups. Metabolites were significantly enriched in amino acid metabolism pathways, including methionine metabolism, glycine and serine metabolism, and tryptophan metabolism. The differentially expressed genes enrichment analysis indicated that antigen processing and presentation, NOD-like receptor signaling pathway, and arginine biosynthesis were enriched with the administration of 10-had. The correlation analysis revealed that glycerophospholipid metabolism and s-adenosylmethionine-dependent methylation processes might be involved in the response to the 10-HDA treatment. Overall, the findings from this study showed that 10-HDA might involve the modulation of certain signaling pathways involved in the inflammatory response, but further research is needed to determine the safety and efficacy as a therapeutic agent.

Framework for global stability analysis of dynamical systems

Dynamical systems that are used to model power grids, the brain, and other physical systems can exhibit coexisting stable states known as attractors. A powerful tool to understand such systems, as well as to better predict when they may "tip" from one stable state to the other, is global stability analysis. It involves identifying the initial conditions that converge to each attractor, known as the basins of attraction, measuring the relative volume of these basins in state space, and quantifying how these fractions change as a system parameter evolves. By improving existing approaches, we present a comprehensive framework that allows for global stability analysis of dynamical systems. Notably, our framework enables the analysis to be made efficiently and conveniently over a parameter range. As such, it becomes an essential tool for stability analysis of dynamical systems that goes beyond local stability analysis offered by alternative frameworks. We demonstrate the effectiveness of our approach on a variety of models, including climate, power grids, ecosystems, and more. Our framework is available as simple-to-use open-source code as part of the DynamicalSystems.jl library.

Single-Cell Characterization of the Frizzled 5 (Fz5) Mutant Mouse and Human Persistent Fetal Vasculature (PFV)

Purpose

Persistent fetal vasculature (PFV) is a pathological condition accounting for 4.8% of children's blindness in the United States. However, the PFV cell composition and pathogenetic mechanisms are poorly understood. This study aims to characterize PFV cell composition and associated molecular features and attempts to lay a foundation for further understanding the disease.

Methods

Immunohistochemistry was conducted to characterize cell types at the tissue level. Single-cell RNA sequencing (sc-RNAseq) was performed on the vitreous cells derived from normal and Fz5 mutant mice at two early postnatal ages and human PFV samples. Bioinformatic tools were used to cluster cells and analyze their molecular features and functions.

Results

The findings of this study are as follows: (1) a total of 10 defined and one undefined cell types were characterized in both the hyaloid vessel system and PFV by sc-RNAseq and immunohistochemistry; (2) neural crest-derived melanocytes, astrocytes, and fibroblasts were specifically retained in the mutant PFV; (3) Fz5 mutants were found to possess more vitreous cells at early postnatal age 3 but returned to similar levels as the wild type at postnatal age 6; (4) altered phagocytic and proliferation environments and cell-cell interactions were detected in the mutant vitreous; (5) the human PFV samples shared fibroblast, endothelial and macrophage cell types with the mouse, but having distinct immune cells including T cells, NK cells and Neutrophils; and last, (6) some neural crest features were also shared between certain mouse and human vitreous cell types.

Conclusions

We characterized PFV cell composition and associated molecular features in the Fz5 mutant mice and two human PFV samples. The excessively migrated vitreous cells, intrinsic molecular properties of these cells, phagocytic environment, and cell-cell interactions may together contribute to PFV pathogenesis. Human PFV shares certain cell types and molecular features with the mouse.

Estimation of Early Postmortem Interval from Long Noncoding RNA Gene Expression in the Incised Cutaneous Wound: An Experimental Study

The assessment of alteration of postmortem RNA expression has forensic significance in estimating postmortem interval. To evaluate wound healing progression and the effect of different postmortem intervals, histopathological changes, immunohistochemical matrix metalloproteinase-9 (MMP-9) expression, and long noncoding fatty acid oxidation (lncFAO), RNA expression was assessed in the incised cutaneous wound model. A full-thickness cutaneous wound was inflicted on 75 rats. All 15 rats were sacrificed at different post-infliction intervals (0, 2, 4, 8 and 10 days), and the cutaneous wounds (n = 5) were excised at different postmortem intervals (0, 5, and 24 h after euthanasia). The maximal inflammatory healing stage was detected at day 4 post-infliction, while near complete healing, thick mature collagen deposition was detected at day 10 post-infliction. LncFAO expression was significantly over-expressed with increasing wound age. MMP-9 was detectable on injury day with continuous elevation until 8 days post-wounding, which later decreased. Although histopathological and immunohistochemical examinations within 24 h postmortem did not show any remarkable changes, lncFAO RNA expression showed a significant negative correlation with hours passed since death. The combined use of histopathological changes, immunohistochemical expression of MMP-9, and molecular expression of lncFAO could be appropriate in wound dating verification. Among these factors, lncFAO could be a reliable indicator in postmortem interval estimation.

Role of macrophage polarization in osteoarthritis (Review)

Osteoarthritis (OA) is a disease involving the whole joint that seriously reduces the living standards of individuals. Traditional treatments include physical therapy, administration of anti-inflammatory and analgesic drugs and injection of glucocorticoids or hyaluronic acid into the joints. However, these methods have limited efficacy and it is difficult to reverse the progression of OA, therefore it is urgent to find new effective treatment methods. Immune microenvironment is significant in the occurrence and development of OA. Recent studies have shown that macrophages are important targets for the treatment of OA. Macrophages are polarized into M1 pro-inflammatory phenotype and M2 anti-inflammatory phenotype under stimulation of different factors, which release and regulate inflammatory response and cartilage growth. Accumulating studies have tried to alleviate OA by regulating macrophage homeostasis. The present study summarized the related studies, discuss the mechanism of various therapeutic reagents on OA, expound the molecular mechanism of drug effect on OA and attempted to provide clues for the treatment of OA.

A novel risk model based on cuproptosis-related lncRNAs predicted prognosis and indicated immune microenvironment landscape of patients with cutaneous melanoma

Cutaneous melanoma (CM) is an aggressive form of malignancy with poor prognostic value. Cuproptosis is a novel type of cell death regulatory mechanism in tumors. However, the role of cuproptosis-related long noncoding RNAs (lncRNAs) in CM remains elusive. The cuproptosis-related lncRNAs were identified using the Pearson correlation algorithm. Through the univariate and multivariate Cox regression analysis, the prognosis of seven lncRNAs associated with cuproptosis was established and a new risk model was constructed. ESTIMATE, CIBERSORT, and single sample gene set enrichment analyses (ssGSEA) were applied to evaluate the immune microenvironment landscape. The Kaplan–Meier survival analysis revealed that the overall survival (OS) of CM patients in the high-risk group was remarkably lower than that of the low-risk group. The result of the validated cohort and the training cohort indicated that the risk model could produce an accurate prediction of the prognosis of CM. The nomogram result demonstrated that the risk score based on the seven prognostic cuproptosis-related lncRNAs was an independent prognostic indicator feature that distinguished it from other clinical features. The result of the immune microenvironment landscape indicated that the low-risk group showed better immunity than high-risk group. The immunophenoscore (IPS) and immune checkpoints results conveyed a better benefit potential for immunotherapy clinical application in the low-risk groups. The enrichment analysis and the gene set variation analysis (GSVA) were adopted to reveal the role of cuproptosis-related lncRNAs mediated by the immune-related signaling pathways in the development of CM. Altogether, the construction of the risk model based on cuproptosis-related lncRNAs can accurately predict the prognosis of CM and indicate the immune microenvironment of CM, providing a new perspective for the future clinical treatment of CM.