The Role of GPNMB in Inflammation

Glycoprotein non-metastatic melanoma protein B (GPNMB): An attractive target in atherosclerosis

Atherosclerosis (AS), the leading cause of cardiovascular diseases, is heavily influenced by inflammation, lipid accumulation, autophagy, and aging. The expression of glycoprotein non-metastatic melanoma B (GPNMB) has been observed to correlate with lipid content, inflammation, and aging, progressively increasing as atherosclerosis advances through its various stages, from baseline to early and advanced phases. However, the interaction between GPNMB and AS is controversial. Knockout of GPNMB has been shown to increase atherosclerotic plaque burden in mice. Conversely, targeted elimination of GPNMB-positive cells reduced atherosclerotic burden. These seemingly contradictory findings underscore the complexity of the issue and highlight the need for further research to reconcile these discrepancies and to elucidate the precise role of GPNMB in the pathogenesis of AS.

Therapeutic targeting of senescent cells in the CNS

Senescent cells accumulate throughout the body with advanced age, diseases and chronic conditions. They negatively impact health and function of multiple systems, including the central nervous system (CNS). Therapies that target senescent cells, broadly referred to as senotherapeutics, recently emerged as potentially important treatment strategies for the CNS. Promising therapeutic approaches involve clearing senescent cells by disarming their pro-survival pathways with 'senolytics'; or dampening their toxic senescence-associated secretory phenotype (SASP) using 'senomorphics'. Following the pioneering discovery of first-generation senolytics dasatinib and quercetin, dozens of additional therapies have been identified, and several promising targets are under investigation. Although potentially transformative, senotherapies are still in early stages and require thorough testing to ensure reliable target engagement, specificity, safety and efficacy. The limited brain penetrance and potential toxic side effects of CNS-acting senotherapeutics pose challenges for drug development and translation to the clinic. This Review assesses the potential impact of senotherapeutics for neurological conditions by summarizing preclinical evidence, innovative methods for target and biomarker identification, academic and industry drug development pipelines and progress in clinical trials.

Bone-marrow macrophage-derived GPNMB protein binds to orphan receptor GPR39 and plays a critical role in cardiac repair

Glycoprotein nonmetastatic melanoma protein B (GPNMB) is a type I transmembrane protein initially identified in nonmetastatic melanomas and has been associated with human heart failure; however, its role in cardiac injury and function remains unclear. Here we show that GPNMB expression is elevated in failing human and mouse hearts after myocardial infarction (MI). Lineage tracing and bone-marrow transplantation reveal that bone-marrow-derived macrophages are the main source of GPNMB in injured hearts. Using genetic loss-of-function models, we demonstrate that GPNMB deficiency leads to increased mortality, cardiac rupture and rapid post-MI left ventricular dysfunction. Conversely, increasing circulating GPNMB levels through viral delivery improves heart function after MI. Single-cell transcriptomics show that GPNMB enhances myocyte contraction and reduces fibroblast activation. Additionally, we identified GPR39 as a receptor for circulating GPNMB, with its absence negating the beneficial effects. These findings highlight a pivotal role of macrophage-derived GPNMBs in post-MI cardiac repair through GPR39 signaling.

ARL13B controls male reproductive tract physiology through primary and Motile Cilia

ARL13B is a small regulatory GTPase that controls ciliary membrane composition in both motile cilia and non-motile primary cilia. In this study, we investigated the role of ARL13B in the efferent ductules, tubules of the male reproductive tract essential to male fertility in which primary and motile cilia co-exist. We used a genetically engineered mouse model to delete Arl13b in efferent ductule epithelial cells, resulting in compromised primary and motile cilia architecture and functions. This deletion led to disturbances in reabsorptive/secretory processes and triggered an inflammatory response. The observed male reproductive phenotype showed significant variability linked to partial infertility, highlighting the importance of ARL13B in maintaining a proper physiological balance in these small ducts. These results emphasize the dual role of both motile and primary cilia functions in regulating efferent duct homeostasis, offering deeper insights into how cilia related diseases affect the male reproductive system.

Identification of conserved and tissue-restricted transcriptional profiles for lipid associated macrophages (LAMs)

Macrophages are essential immune cells present in all tissues, and are vital for maintaining tissue homeostasis, immune surveillance, and immune responses. Considerable efforts have identified shared and tissue-specific gene programs for macrophages across organs during homeostasis. This information has dramatically enhanced our understanding of tissue-restricted macrophage programming and function. However, few studies have addressed the overlapping and tissue-specific responses of macrophage subsets following inflammatory responses. One subset of macrophages that has been observed across several studies, lipid-associated macrophages (LAMs), have gained interest due to their unique role in lipid metabolism and potential as a therapeutic target. LAMs have been associated with regulating disease outcomes in metabolically related disorders including atherosclerosis, obesity, and nonalcoholic fatty liver disease (NAFLD). In this study, we utilized single-cell RNA sequencing (scRNAseq) data to profile LAMs across multiple tissues and sterile inflammatory conditions in mice and humans. Integration of data from various disease models revealed that LAMs share a set of conserved transcriptional profiles, including Trem2 and Lpl, but also identified key sets of tissue-specific LAM gene programs. Importantly, the shared LAM markers were highly conserved with human LAM populations that also emerge in chronic inflammatory settings. Overall, this analysis provides a detailed transcriptional landscape of tissue-restricted and shared LAM gene programs and offers insights into their roles in metabolic and chronic inflammatory diseases. These data may help instruct appropriate targets for broad or tissue-restricted therapeutic interventions to modulate LAM populations in disease.

Biofluid GPNMB/osteoactivin as a potential biomarker of ageing: A cross-sectional study

Background

Glycoprotein non-metastatic melanoma B (GPNMB)/osteoactivin was first identified in the human melanoma cell lines. GPNMB plays a key role in the anti-inflammatory and antioxidative functions as well as osteoblast differentiation, cancer progression, and tissue regeneration. Recently, GPNMB was used as an anti-aging vaccine for mice. The present study aimed to investigate the potential of biofluid GPNMB as an aging biomarker in humans using serum and urine samples from an aging Chinese population.

Methods

We analyzed RNA-sequencing data (GSE132040) from 17 murine organs across different ages to assess the gene expression of potential ageing biomarkers. Spearman's correlation coefficients were used to evaluate the relationship between gene expression and age. Meanwhile, a cross-sectional population study was conducted, which included 473 participants (aged 25-91 years), a representative subset of participants from the Peng Zu Study on Healthy Ageing in China (Peng Zu Cohort). Biofluid GPNMB levels were measured by ELISA. The associations of serum and urine GPNMB levels with various clinical and anthropometrical indices were assessed using ANOVA, Kruskal-Wallis H test, and univariate and multivariate linear regression analyses.

Results

In mice, the Gpnmb mRNA expression levels showed a significant positive association with age in multiple organs in mice (P < 0.05). In Peng Zu Cohort, biofluid (both serum and urine) GPNMB levels showed a positive correlation with age (P < 0.05). Univariate linear regression analysis revealed that serum GPNMB levels were negatively associated with skeletal muscle mass index (SMI, P < 0.05) and insulin-like growth factor 1 (IGF-1, P < 0.05), and urine GPNMB levels showed a negative association with total bile acids (TBA, P < 0.05). Multivariate linear regression analysis further indicated that serum GPNMB levels negatively correlated with the systemic immune-inflammation index (SII, P < 0.05), and the urine GPNMB levels maintained a negative association with TBA (P < 0.05), additionally, urine GPNMB levels in men were significantly lower than in women (P < 0.05).

Conclusions

The biofluid GPNMB was a strong clinical biomarker candidate for estimating biological aging.

Targeting Senescent Cells in Atherosclerosis: Pathways to Novel Therapies

Targeting senescent cells has recently emerged as a promising strategy for treating age-related diseases, such as atherosclerosis, which significantly contributes to global cardiovascular morbidity and mortality. This review elucidates the role of senescent cells in the development of atherosclerosis, including persistently damaging DNA, inducing oxidative stress and secreting pro-inflammatory factors known as the senescence-associated secretory phenotype. Therapeutic approaches targeting senescent cells to mitigate atherosclerosis are summarized in this review, which include the development of senotherapeutics and immunotherapies. These therapies are designed to either remove these cells or suppress their deleterious effects. These emerging therapies hold potential to decelerate or even alleviate the progression of AS, paving the way for new avenues in cardiovascular research and treatment.

Olfr2-positive macrophages originate from monocytes proliferate in situ and present a pro-inflammatory foamy-like phenotype

AIMS

Olfactory receptor 2 (Olfr2) has been identified in a minimum of 30% of vascular macrophages, and its depletion was shown to reduce atherosclerosis progression. Mononuclear phagocytes, including monocytes and macrophages within the vessel wall, are major players in atherosclerosis. Single-cell RNA sequencing studies revealed that atherosclerotic artery walls encompass several monocytes and vascular macrophages, defining at least nine distinct subsets potentially serving diverse functions in disease progression. This study investigates the functional phenotype and ontogeny of Olfr2-expressing vascular macrophages in atherosclerosis.

METHODS AND RESULTS

Olfr2+ macrophages rapidly increase in Apoe-/- mice's aorta when fed a Western diet (WD). Mass cytometry showed that Olfr2+ cells are clustered within the CD64 high population and enriched for CD11c and Ccr2 markers. Olfr2+ macrophages express many pro-inflammatory cytokines, including Il1b, Il6, Il12, and Il23, and chemokines, including Ccl5, Cx3cl1, Cxcl9, and Ccl22. By extracting differentially expressed genes from bulk RNA sequencing (RNA-seq) of Olfr2+ vs. Olfr2- macrophages, we defined a signature that significantly mapped to single-cell data of plaque myeloid cells, including monocytes, subendothelial MacAir, and Trem2Gpnmb foamy macrophages. By adoptive transfer experiments, we identified that Olfr2 competent monocytes from CD45.1Apoe-/-Olfr2+/+ mice transferred into CD45.2Apoe-/-Olfr2-/- recipient mice fed WD for 12 weeks, accumulate in the atherosclerotic aorta wall already at 72 h, and differentiate in macrophages. Olfr2+ macrophages showed significantly increased BrdU incorporation compared to Olfr2- macrophages. Flow cytometry confirmed that at least 50% of aortic Olfr2+ macrophages are positive for BODIPY staining and have increased expression of both tumour necrosis factor and interleukin 6 compared to Olfr2- macrophages. Gene set enrichment analysis of the Olfr2+ macrophage signature revealed a similar enrichment pattern in human atherosclerotic plaques, particularly within foamy/TREM2hi-Mφ and monocytes.

CONCLUSIONS

In summary, we conclude that Olfr2+ macrophages in the aorta originate from monocytes and can accumulate at the early stages of disease progression. These cells can undergo differentiation into MacAir and Trem2Gpnmb foamy macrophages, exhibiting proliferative and pro-inflammatory potentials. This dynamic behaviour positions them as key influencers in shaping the myeloid landscape within the atherosclerotic plaque.

The post-stroke young adult brain has limited capacity to re-express the gene expression patterns seen during early postnatal brain development

The developmental origins of the brain's response to injury can play an important role in recovery after a brain lesion. In this study, we investigated whether the ischemic young adult brain can re-express brain plasticity genes that were active during early postnatal development. Differentially expressed genes in the cortex of juvenile post-natal day 3 and the peri-infarcted cortical areas of young, 3-month-old post-stroke rats were identified using fixed-effects modeling within an empirical Bayes framework through condition-specific comparison. To further analyze potential biological processes, upregulated and downregulated genes were assessed for enrichment using GSEA software. The genes showing the highest expression changes were subsequently verified through RT-PCR. Our findings indicate that the adult brain partially recapitulates the gene expression profile observed in the juvenile brain but fails to upregulate many genes and pathways necessary for brain plasticity. Of the upregulated genes in post-stroke brains, specific roles have not been assigned to Apobec1, Cenpf, Ect2, Folr2, Glipr1, Myo1f, and Pttg1. New genes that failed to upregulate in the adult post-stroke brain include Bex4, Cd24, Klhl1/Mrp2, Trim67, and St8sia2. Among the upregulated pathways, the largest change was observed in the KEGG pathway "One carbon pool of folate," which is necessary for cellular proliferation, followed by the KEGG pathway "Antifolate resistance," whose genes mainly encode the family of ABC transporters responsible for the efflux of drugs that have entered the brain. We also noted three less-described downregulated KEGG pathways in experimental models: glycolipid biosynthesis, oxytocin, and cortisol pathways, which could be relevant as therapeutic targets. The limited brain plasticity of the adult brain is illustrated through molecular and histological analysis of the axonal growth factor, KIF4. Collectively, these results strongly suggest that further research is needed to decipher the complex genetic mechanisms that prevent the re-expression of brain plasticity-associated genes in the adult brain.

Overview of pro-inflammatory and pro-survival components in neuroinflammatory signalling and neurodegeneration

Neurodegenerative diseases (NDDs) are identified by the progressive deterioration of neurons and a subsequent decline in cognitive function, creating an enormous burden on the healthcare system globally. Neuroinflammation is an intricate procedure that initiates the immune response in the central nervous system (CNS) and significantly impacts the expansion of NDDs. This study scrutinizes the complicated interaction between neuronal degeneration and neuroinflammation, with an appropriate emphasis on their reciprocal impacts. It also describes how neuroinflammatory reactions in NDDs are controlled by activating certain pro-inflammatory transcription factors, including p38 MAPK, FAF1, Toll-like receptors (TLRs), and STAT3. Alternatively, it evaluates the impact of pro-survival transcription factors, such as the SOCS pathway, YY1, SIRT1, and MEF2, which provide neuroprotective protection against damage triggered by neuroinflammation. Moreover, we study the feasibility of accommodating drug repositioning as a therapeutic approach for treating neuroinflammatory disorders. This suggests the use of existing medications for novel utilization in the treatment of NDDs. Furthermore, the study intends to reveal novel biomarkers of neuroinflammation that contribute fundamental observation for the initial detection and diagnosis of these disorders. This study aims to strengthen therapy interference and augment patient outcomes by combining ongoing data and evaluating novel therapeutic and diagnostic approaches. The goal is to devote the growth of an effective strategy to reducing the impact of neuroinflammation on neuronal protection in NDDs.

Spatiotemporal transcriptomic mapping of regenerative inflammation in skeletal muscle reveals a dynamic multilayered tissue architecture

Tissue regeneration is orchestrated by macrophages that clear damaged cells and promote regenerative inflammation. How macrophages spatially adapt and diversify their functions to support the architectural requirements of actively regenerating tissue remains unknown. In this study, we reconstructed the dynamic trajectories of myeloid cells isolated from acutely injured and early stage dystrophic muscles. We identified divergent subsets of monocytes/macrophages and DCs and validated markers (e.g., glycoprotein NMB [GPNMB]) and transcriptional regulators associated with defined functional states. In dystrophic muscle, specialized repair-associated subsets exhibited distinct macrophage diversity and reduced DC heterogeneity. Integrating spatial transcriptomics analyses with immunofluorescence uncovered the ordered distribution of subpopulations and multilayered regenerative inflammation zones (RIZs) where distinct macrophage subsets are organized in functional zones around damaged myofibers supporting all phases of regeneration. Importantly, intermittent glucocorticoid treatment disrupted the RIZs. Our findings suggest that macrophage subtypes mediated the development of the highly ordered architecture of regenerative tissues, unveiling the principles of the structured yet dynamic nature of regenerative inflammation supporting effective tissue repair.

Spatial transcriptomic analysis of tumour-immune cell interactions in melanoma arising from congenital melanocytic nevus

BACKGROUND

Studies on the interaction between tumour-infiltrating immune cells (TIICs) and tumour cells in melanoma arising from congenital melanocytic nevus (CMN) are lacking.

OBJECTIVE

The aim of this study was to determine the intratumoral immune landscape of TIICs and tumour cells during invasion and metastasis.

METHODS

Tissue specimens were obtained from patients with melanoma originating from CMN. Differential gene expression in melanoma cells and TIICs during invasion and metastasis was determined using spatial transcriptomics.

RESULTS

As invasion depth increased, the expression of LGALS3, known to induce tumour-driven immunosuppression, increased in melanoma cells. In T cells, the expression of genes that inhibit T-cell activation increased with increasing invasion depth. In macrophages, the expression of genes related to the anti-inflammatory M2 phenotype was upregulated with increasing invasion depth. Compared to primary tumour cells, melanoma cells in metastatic lesions showed upregulated expression of genes associated with cancer immune evasion, including AXL and EPHA2, which impede T-cell recruitment, and BST2, associated with M2 polarization. Furthermore, T cells showed increased expression of genes related to immunosuppression, and macrophages exhibited increased expression of genes associated with the M2 phenotype.

CONCLUSIONS

The interaction between melanomas arising from CMN and TIICs may be important for tumour progression and metastasis.

ASO-mediated knockdown of GPNMB in mutant- GRN and Grn -deficient peripheral myeloid cells disrupts lysosomal function and immune responses

Background

Increases in GPNMB are detectable in FTD- GRN cerebrospinal fluid (CSF) and post-mortem brain, and brains of aged Grn -deficient mice. Although no upregulation of GPNMB is observed in the brains of young Grn -deficient mice, peripheral immune cells of these mice do exhibit this increase in GPNMB. Importantly, the functional significance of GPNMB upregulation in progranulin-deficient states is currently unknown. Given that GPNMB has been discussed as a potential therapeutic target in GRN -mediated neurodegeneration, it is vital for the field to determine what the normal function of GPNMB is in the immune system, and whether targeting GPNMB will elicit beneficial or deleterious effects.

Methods

The effects of GPNMB knock-down via antisense oligonucleotide (ASO) were assessed in peripheral blood mononuclear cells (PBMCs) from 25 neurologically healthy controls (NHCs) and age- and sex-matched FTD- GRN patients, as well as peritoneal macrophages (pMacs) from progranulin-deficient ( Grn -/- ) and B6 mice. Lysosomal function, antigen presentation and MHC-II processing and recycling were assessed, as well as cytokine release and transcription.

Results

We demonstrate here that ASO-mediated knockdown of GPNMB increases lysosomal burden and cytokine secretion in FTD-GRN carrier and neurologically healthy controls (NHCs) monocytes. ASO-mediated knockdown of GPNMB in Grn -deficient macrophages decreased lysosomal pan-cathepsin activity and protein degradation. In addition, ASO-mediated knockdown of GPNMB increased MHC-II surface expression, which was driven by decreased MHC-II uptake and recycling, in macrophages from Grn -deficient females. Finally, ASO-mediated knockdown of GPNMB dysregulated IFNγ-stimulated cytokine transcription and secretion by mouse macrophages due to the absence of regulatory actions of the GPNMB extracellular fragment (ECF).

Conclusions

Our data herein reveals that GPNMB has a regulatory effect on multiple immune effector functions, including capping inflammation and immune responses in myeloid cells via secretion of its ECF. Therefore, in progranulin-deficient states, the drastic upregulation in GPNMB transcript and protein may represent a compensatory mechanism to preserve lysosomal function in myeloid cells. These novel findings indicate that targeted depletion in FTD- GRN would not be a rational therapeutic strategy because it is likely to dysregulate important immune cell effector functions.

Glycoprotein Non-metastatic Melanoma Protein B (GPNMB) Protects Against Neuroinflammation and Neuronal Loss in Pilocarpine-induced Epilepsy via the Regulation of Microglial Polarization

Epilepsy is a progressive neurodegenerative disease highlighted by recurrent seizures, neuroinflammation, and the loss of neurons. Microglial dysfunction is commonly found in epileptic foci and contributes to neuroinflammation in the initiation and progression of epilepsy. Glycoprotein non-metastatic melanoma protein B (GPNMB), a transmembrane glycoprotein, has been involved in the microglial activation and neuroinflammation response. The present study investigated the functional significance of GPNMB in epilepsy. A proven model of epilepsy was established by intraperitoneal injection of pilocarpine to male Sprague Dawley rats. Lentivirus vectors carrying GPNMB or GPNMB short hairpin RNA (shGPNMB) were injected into the hippocampus to induce overexpression or knockdown of GPNMB. GPNMB expression was significantly upregulated and overexpression of GPNMB in the hippocampus reduced seizure activity and neuronal loss after status epilepticus (SE). We here focused on the effects of GPNMB deficiency on neuronal injury and microglia polarization 28 days after SE. GPNMB knockdown accelerated neuronal damage in the hippocampus, evidenced by increased neuron loss and neuronal cell apoptosis. Following GPNMB knockdown, M1 polarization (iNOS) and secretion of pro-inflammatory cytokines IL-6, IL-1β, and TNF-α were increased, and M2 polarization (Arg1) and secretion of anti-inflammatory cytokines IL-4, IL-10, and TGF-β were decreased. BV2 cells were used to further confirm the regulatory role of GPNMB in modulating phenotypic transformations and inflammatory cytokine expressions in microglia. In conclusion, these results indicated that GPNMB suppressed epilepsy through repression of hippocampal neuroinflammation, suggesting that GPNMB might be considered the potential neurotherapeutic target for epilepsy management and play a protective role against epilepsy by modulating the polarization of microglia.

Epigenetic associations of GPNMB rs199347 variant with alcohol consumption in Parkinson's disease

Introduction

Alcohol consumption can induce a neuroinflammatory response and contribute to the progression of neurodegeneration. However, its association with Parkinson's disease (PD), the second most common neurodegenerative disorder, remains undetermined. Recent studies suggest that the glycoprotein non-metastatic melanoma protein B (GPNMB) is a potential biomarker for PD. We evaluated the association of rs199347, a variant of the GPNMB gene, with alcohol consumption and methylation upstream of GPNMB.

Methods

We retrieved genetic and DNA methylation data obtained from participants enrolled in the Taiwan Biobank (TWB) between 2008 and 2016. After excluding individuals with incomplete or missing information about potential PD risk factors, we included 1,357 participants in our final analyses. We used multiple linear regression to assess the association of GPNMB rs199347 and chronic alcohol consumption (and other potential risk factors) with GPNMB cg17274742 methylation.

Results

There was no difference between the distribution of GPNMB rs199347 genotypes between chronic alcohol consumers and the other study participants. A significant interaction was observed between the GPNMB rs199347 variant and alcohol consumption (p = 0.0102) concerning cg17274742 methylation. Compared to non-chronic alcohol consumers with the AA genotype, alcohol drinkers with the rs199347 GG genotype had significantly lower levels (hypomethylation) of cg17274742 (p = 0.0187).

Conclusion

Alcohol consumption among individuals with the rs199347 GG genotype was associated with lower levels of cg17274742 methylation, which could increase expression of the GPNMB gene, an important neuroinflammatory-related risk gene for PD.

Chronically activated microglia in ALS gradually lose their immune functions and develop unconventional proteome

Neuroinflammation and chronic activation of microglial cells are the prominent features of amyotrophic lateral sclerosis (ALS) pathology. While alterations in the mRNA profile of diseased microglia have been well documented, the actual microglia proteome remains poorly characterized. Here we performed a functional characterization together with proteome analyses of microglial cells at different stages of disease in the SOD1-G93A model of ALS. Functional analyses of microglia derived from the lumbar spinal cord of symptomatic mice revealed: (i) remarkably high mitotic index (close to 100% cells are Ki67+) (ii) significant decrease in phagocytic capacity when compared to age-matched control microglia, and (iii) diminished response to innate immune challenges in vitro and in vivo. Proteome analysis revealed a development of two distinct molecular signatures at early and advanced stages of disease. While at early stages of disease, we identified several proteins implicated in microglia immune functions such as GPNMB, HMBOX1, at advanced stages of disease microglia signature at protein level was characterized with a robust upregulation of several unconventional proteins including rootletin, major vaults proteins and STK38. Upregulation of GPNMB and rootletin has been also found in the spinal cord samples of sporadic ALS. Remarkably, the top biological functions of microglia, in particular in the advanced disease, were not related to immunity/immune response, but were highly enriched in terms linked to RNA metabolism. Together, our results suggest that, over the course of disease, chronically activated microglia develop unconventional protein signatures and gradually lose their immune identity ultimately turning into functionally inefficient immune cells.

Targeting the oncogenic m6A demethylase FTO suppresses tumourigenesis and potentiates immune response in hepatocellular carcinoma

OBJECTIVE

Fat mass and obesity-associated protein (FTO), an eraser of N 6-methyadenosine (m6A), plays oncogenic roles in various cancers. However, its role in hepatocellular carcinoma (HCC) is unclear. Furthermore, small extracellular vesicles (sEVs, or exosomes) are critical mediators of tumourigenesis and metastasis, but the relationship between FTO-mediated m6A modification and sEVs in HCC is unknown.

DESIGN

The functions and mechanisms of FTO and glycoprotein non-metastatic melanoma protein B (GPNMB) in HCC progression were investigated in vitro and in vivo. Neutralising antibody of syndecan-4 (SDC4) was used to assess the significance of sEV-GPNMB. FTO inhibitor CS2 was used to examine the effects on anti-PD-1 and sorafenib treatment.

RESULTS

FTO expression was upregulated in patient HCC tumours. Functionally, FTO promoted HCC cell proliferation, migration and invasion in vitro, and tumour growth and metastasis in vivo. FTO knockdown enhanced the activation and recruitment of tumour-infiltrating CD8+ T cells. Furthermore, we identified GPNMB to be a downstream target of FTO, which reduced the m6A abundance of GPNMB, hence, stabilising it from degradation by YTH N 6-methyladenosine RNA binding protein F2. Of note, GPNMB was packaged into sEVs derived from HCC cells and bound to the surface receptor SDC4 of CD8+ T cells, resulting in the inhibition of CD8+ T cell activation. A potential FTO inhibitor, CS2, suppresses the oncogenic functions of HCC cells and enhances the sensitivity of anti-PD-1 and sorafenib treatment.

CONCLUSION

Targeting the FTO/m6A/GPNMB axis could significantly suppress tumour growth and metastasis, and enhance immune activation, highlighting the potential of targeting FTO signalling with effective inhibitors for HCC therapy.

Transcriptomic evaluation of skin tape-strips in children with allergic asthma uncovers epidermal barrier dysfunction and asthma-associated biomarkers abnormalities

INTRODUCTION

Tape-strips, a minimally invasive method validated for the evaluation of several skin diseases, may help identify asthma-specific biomarkers in the skin of children with allergic asthma.

METHODS

Skin tape-strips were obtained and analyzed with RNA-Seq from children with moderate allergic asthma (MAA) (n = 11, mean age 7.00; SD = 1.67), severe allergic asthma (SAA) (n = 9, mean age 9.11; SD = 2.37), and healthy controls (HCs) (n = 12, mean age 7.36; SD = 2.03). Differentially expressed genes (DEGs) were identified by fold change ≥2 with a false discovery rate <0.05. Transcriptomic biomarkers were analyzed for their accuracy in distinguishing asthma from HCs, their relationships with asthma-related outcomes (exacerbation rate, lung function-FEV1, IOS-R5-20, and lung inflammation-FeNO), and their links to skin (barrier and immune response) and lung (remodeling, metabolism, aging) pathogenetic pathways.

RESULTS

RNA-Seq captured 1113 in MAA and 2117 DEGs in SAA. Epidermal transcriptomic biomarkers for terminal differentiation (FLG/filaggrin), cell adhesion (CDH19, JAM2), lipid biosynthesis/metabolism (ACOT2, LOXL2) were significantly downregulated. Gene set variation analysis revealed enrichment of Th1/IFNγ pathways (p < .01). MAA and SAA shared downregulation of G-protein-coupled receptor (OR4A16, TAS1R3), upregulation of TGF-β/ErbB signaling-related (ACVR1B, EGFR, ID1/2), and upregulation of mitochondrial-related (HIGD2A, VDAC3, NDUFB9) genes. Skin transcriptomic biomarkers correlated with the annualized exacerbation rate and with lung function parameters. A two-gene classifier (TSSC4-FAM212B) was able to differentiate asthma from HCs with 100% accuracy.

CONCLUSION

Tape-strips detected epithelial barrier and asthma-associated signatures in normal-appearing skin from children with allergic asthma and may serve as an alternative to invasive approaches for evaluating asthma endotypes.

Longitudinal Neuropathological Consequences of Extracranial Radiation Therapy in Mice

Cancer-related cognitive impairment (CRCI) is a consequence of chemotherapy and extracranial radiation therapy (ECRT). Our prior work demonstrated gliosis in the brain following ECRT in SKH1 mice. The signals that induce gliosis were unclear. Right hindlimb skin from SKH1 mice was treated with 20 Gy or 30 Gy to induce subclinical or clinical dermatitis, respectively. Mice were euthanized at 6 h, 24 h, 5 days, 12 days, and 25 days post irradiation, and the brain, thoracic spinal cord, and skin were collected. The brains were harvested for spatial proteomics, immunohistochemistry, Nanostring nCounter® glial profiling, and neuroinflammation gene panels. The thoracic spinal cords were evaluated by immunohistochemistry. Radiation injury to the skin was evaluated by histology. The genes associated with neurotransmission, glial cell activation, innate immune signaling, cell signal transduction, and cancer were differentially expressed in the brains from mice treated with ECRT compared to the controls. Dose-dependent increases in neuroinflammatory-associated and neurodegenerative-disease-associated proteins were measured in the brains from ECRT-treated mice. Histologic changes in the ECRT-treated mice included acute dermatitis within the irradiated skin of the hindlimb and astrocyte activation within the thoracic spinal cord. Collectively, these findings highlight indirect neuronal transmission and glial cell activation in the pathogenesis of ECRT-related CRCI, providing possible signaling pathways for mitigation strategies.

Aging impairs cold-induced beige adipogenesis and adipocyte metabolic reprogramming

The energy-burning capability of beige adipose tissue is a potential therapeutic tool for reducing obesity and metabolic disease, but this capacity is decreased by aging. Here, we evaluate the impact of aging on the profile and activity of adipocyte stem and progenitor cells (ASPCs) and adipocytes during the beiging process in mice. We found that aging increases the expression of Cd9 and other fibro-inflammatory genes in fibroblastic ASPCs and blocks their differentiation into beige adipocytes. Fibroblastic ASPC populations from young and aged mice were equally competent for beige differentiation in vitro, suggesting that environmental factors suppress adipogenesis in vivo. Examination of adipocytes by single nucleus RNA-sequencing identified compositional and transcriptional differences in adipocyte populations with aging and cold exposure. Notably, cold exposure induced an adipocyte population expressing high levels of de novo lipogenesis (DNL) genes, and this response was severely blunted in aged animals. We further identified Npr3, which encodes the natriuretic peptide clearance receptor, as a marker gene for a subset of white adipocytes and an aging-upregulated gene in adipocytes. In summary, this study indicates that aging blocks beige adipogenesis and dysregulates adipocyte responses to cold exposure and provides a resource for identifying cold and aging-regulated pathways in adipose tissue.

Transcriptomic Insights into Different Stimulation Intensity of Electroacupuncture in Treating COPD in Rat Models

Background

Electroacupuncture (EA), with varying stimulation intensities, has demonstrated therapeutic potentials in both animal and clinical studies for the treatment of chronic obstructive pulmonary disease (COPD). However, a comprehensive investigation of the intensity-related effects, particularly 1mA and 3mA of EA, and the underlying mechanisms remains lacking.

Methods

A COPD rat model was established by prolonged exposure to cigarette smoke and intermittent intratracheal instillation of lipopolysaccharide. EA treatment was administered at acupoints BL13 (Feishu) and ST36 (Zusanli), 20 minutes daily for 2 weeks, with intensities of 1mA and 3mA. EA effectiveness was evaluated by pulmonary function, histopathological change, serum level of inflammatory cytokines, and level of oxidative stress markers in serum and lung tissues. Transcriptome profiling and weighted gene co-expression network analysis (WGCNA) were performed to reveal gene expression patterns and identify hub genes. Real-time quantitative PCR (RT-qPCR) and Western blot (WB) were performed to detect the mRNA and protein expression levels, respectively.

Results

EA at both 1mA and 3mA exerted differing therapeutic effects by improving lung function and reducing inflammation and oxidative stress in COPD rats. Transcriptome analysis revealed distinct expression patterns between the two groups, functionally corresponding to shared and intensity-specific (1mA and 3mA) enriched pathways. Eight candidate genes were identified, including Aqp9, Trem1, Mrc1, and Gpnmb that were downregulated by EA and upregulated in COPD. Notably, Msr1 and Slc26a4 exclusively downregulated in EA-1mA, while Pde3a and Bmp6 upregulated solely in EA-3mA. WGCNA constructed 5 key modules and elucidated the module-trait relationship, with the aforementioned 8 genes being highlighted. Additionally, their mRNA and protein levels were validated by RT-qPCR and WB.

Conclusion

Our results demonstrated that 1mA and 3mA intensities induce distinct gene expression patterns at the transcriptional level, associated with shared and 1mA vs 3mA-specific enriched pathways. Genes Mrc1, Gpnmb, Trem1, and Aqp9 emerge as promising targets, and further studies are needed to elucidate their functional consequences in COPD.

Identification and classification of glioma subtypes based on RNA-binding proteins

BACKGROUND

Glioma is a common and aggressive primary malignant cancer known for its high morbidity, mortality, and recurrence rates. Despite this, treatment options for glioma are currently restricted. The dysregulation of RBPs has been linked to the advancement of several types of cancer, but their precise role in glioma evolution is still not fully understood. This study sought to investigate how RBPs may impact the development and prognosis of glioma, with potential implications for prognosis and therapy.

METHODS

RNA-seq profiles of glioma and corresponding clinical data from the CGGA database were initially collected for analysis. Unsupervised clustering was utilized to identify crucial tumor subtypes in glioma development. Subsequent time-series analysis and MS model were employed to track the progression of these identified subtypes. RBPs playing a significant role in glioma progression were then pinpointed using WGCNA and Lasso Cox regression models. Functional analysis of these key RBP-related genes was conducted through GSEA. Additionally, the CIBERSORT algorithm was utilized to estimate immune infiltrating cells, while the STRING database was consulted to uncover potential mechanisms of the identified biomarkers.

RESULTS

Six tumor subgroups were identified and found to be highly homogeneous within each subgroup. The progression stages of these tumor subgroups were determined using time-series analysis and a MS model. Through WGCNA, Lasso Cox, and multivariate Cox regression analysis, it was confirmed that BCLAF1 is correlated with survival in glioma patients and is closely linked to glioma progression. Functional annotation suggests that BCLAF1 may impact glioma progression by influencing RNA splicing, which in turn affects the cell cycle, Wnt signaling pathway, and other cancer development pathways.

CONCLUSIONS

The study initially identified six subtypes of glioma progression and assessed their malignancy ranking. Furthermore, it was determined that BCLAF1 could serve as an RBP-related prognostic marker, offering significant implications for the clinical diagnosis and personalized treatment of glioma.

Machine learning and deep learning to identifying subarachnoid haemorrhage macrophage-associated biomarkers by bulk and single-cell sequencing

We investigated subarachnoid haemorrhage (SAH) macrophage subpopulations and identified relevant key genes for improving diagnostic and therapeutic strategies. SAH rat models were established, and brain tissue samples underwent single-cell transcriptome sequencing and bulk RNA-seq. Using single-cell data, distinct macrophage subpopulations, including a unique SAH subset, were identified. The hdWGCNA method revealed 160 key macrophage-related genes. Univariate analysis and lasso regression selected 10 genes for constructing a diagnostic model. Machine learning algorithms facilitated model development. Cellular infiltration was assessed using the MCPcounter algorithm, and a heatmap integrated cell abundance and gene expression. A 3 × 3 convolutional neural network created an additional diagnostic model, while molecular docking identified potential drugs. The diagnostic model based on the 10 selected genes achieved excellent performance, with an AUC of 1 in both training and validation datasets. The heatmap, combining cell abundance and gene expression, provided insights into SAH cellular composition. The convolutional neural network model exhibited a sensitivity and specificity of 1 in both datasets. Additionally, CD14, GPNMB, SPP1 and PRDX5 were specifically expressed in SAH-associated macrophages, highlighting its potential as a therapeutic target. Network pharmacology analysis identified some targeting drugs for SAH treatment. Our study characterised SAH macrophage subpopulations and identified key associated genes. We developed a robust diagnostic model and recognised CD14, GPNMB, SPP1 and PRDX5 as potential therapeutic targets. Further experiments and clinical investigations are needed to validate these findings and explore the clinical implications of targets in SAH treatment.

Molecular mechanisms and potential therapeutic targets in the pathogenesis of hypertension in visceral adipose tissue induced by a high-fat diet

Background

Hypertension (HTN) presents a significant global public health challenge with diverse causative factors. The accumulation of visceral adipose tissue (VAT) due to a high-fat diet (HFD) is an independent risk factor for HTN. While various studies have explored pathogenic mechanisms, a comprehensive understanding of impact of VAT on blood pressure necessitates bioinformatics analysis.

Methods

Datasets GSE214618 and GSE188336 were acquired from the Gene Expression Omnibus and analyzed to identify shared differentially expressed genes between HFD-VAT and HTN-VAT. Gene Ontology enrichment and protein-protein interaction analyses were conducted, leading to the identification of hub genes. We performed molecular validation of hub genes using RT-qPCR, Western-blotting and immunofluorescence staining. Furthermore, immune infiltration analysis using CIBERSORTx was performed.

Results

This study indicated that the predominant characteristic of VAT in HTN was related to energy metabolism. The red functional module was enriched in pathways associated with mitochondrial oxidative respiration and ATP metabolism processes. Spp1, Postn, and Gpnmb in VAT were identified as hub genes on the pathogenic mechanism of HTN. Proteins encoded by these hub genes were closely associated with the target organs-specifically, the resistance artery, aorta, and heart tissue. After treatment with empagliflozin, there was a tendency for Spp1, Postn, and Gpnmb to decrease in VAT. Immune infiltration analysis confirmed that inflammation and immune response may not be the main mechanisms by which visceral adiposity contributes to HTN.

Conclusions

Our study pinpointed the crucial causative factor of HTN in VAT following HFD. Spp1, Postn, and Gpnmb in VAT acted as hub genes that promote elevated blood pressure and can be targets for HTN treatment. These findings contributed to therapeutic strategies and prognostic markers for HTN.

Common genetic risk for Parkinson's disease and dysfunction of the endo-lysosomal system

Parkinson's disease is a progressive neurological disorder, characterized by prominent movement dysfunction. The past two decades have seen a rapid expansion of our understanding of the genetic basis of Parkinson's, initially through the identification of monogenic forms and, more recently, through genome-wide association studies identifying common risk variants. Intriguingly, a number of cellular pathways have emerged from these analysis as playing central roles in the aetiopathogenesis of Parkinson's. In this review, the impact of data deriving from genome-wide analyses for Parkinson's upon our functional understanding of the disease will be examined, with a particular focus on examples of endo-lysosomal and mitochondrial dysfunction. The challenges of moving from a genetic to a functional understanding of common risk variants for Parkinson's will be discussed, with a final consideration of the current state of the genetic architecture of the disorder. This article is part of a discussion meeting issue 'Understanding the endo-lysosomal network in neurodegeneration'.

Tumor associated microglia/macrophages utilize GPNMB to promote tumor growth and alter immune cell infiltration in glioma

Tumor-associated microglia and blood-derived macrophages (TAMs) play a central role in modulating the immune suppressive microenvironment in glioma. Here, we show that GPNMB is predominantly expressed by TAMs in human glioblastoma multiforme and the murine RCAS-PDGFb high grade glioma model. Loss of GPNMB in the in vivo tumor microenvironment results in significantly smaller tumor volumes and generates a pro-inflammatory innate and adaptive immune cell microenvironment. The impact of host-derived GPNMB on tumor growth was confirmed in two distinct murine glioma cell lines in organotypic brain slices from GPNMB-KO and control mice. Using published data bases of human glioma, the elevated levels in TAMs could be confirmed and the GPNMB expression correlated with a poorer survival.

Targeting aging and age-related diseases with vaccines

Aging is a major risk factor for numerous chronic diseases. Vaccination offers a promising strategy to combat these age-related diseases by targeting specific antigens and inducing immune responses. Here, we provide a comprehensive overview of recent advances in vaccine-based interventions targeting these diseases, including Alzheimer's disease, type II diabetes, hypertension, abdominal aortic aneurysm, atherosclerosis, osteoarthritis, fibrosis and cancer, summarizing current approaches for identifying disease-associated antigens and inducing immune responses against these targets. Further, we reflect on the recent development of vaccines targeting senescent cells, as a strategy for more broadly targeting underlying causes of aging and associated pathologies. In addition to highlighting recent progress in these areas, we discuss important next steps to advance the therapeutic potential of these vaccines, including improving and robustly demonstrating efficacy in human clinical trials, as well as rigorously evaluating the safety and long-term effects of these vaccine strategies.

Novel subsets of peripheral immune cells associated with promoting stroke recovery in mice

AIMS

Peripheral immune cells infiltrating into the brain trigger neuroinflammation after an ischemic stroke. Partial immune cells reprogram their function for neural repair. Which immune cells promote ischemic brain recovery needs further identification.

METHODS

We performed single-cell transcriptomic profiling of CD45high immune cells isolated from the ischemic hemisphere at subacute (5 days) and chronic (14 days) stages after ischemic stroke.

RESULTS

A subset of phagocytic macrophages was associated with neuron projection regeneration and tissue remodeling. We also identified a unique type of T cells with highly expressed macrophage markers, including C1q, Apoe, Hexb, and Fcer1g, which showed high abilities in tissue remodeling, myelination regulation, wound healing, and anti-neuroinflammation. Moreover, natural killer cells decreased cytotoxicity and increased energy and metabolic function in the chronic stage after ischemic stroke. Two subgroups of neutrophils upregulated CCL signals to recruit peripheral immune cells and released CXCL2 to keep self-recruiting at the chronic stage.

CONCLUSIONS

We identified subsets of peripheral immune cells that may provide potential therapeutic targets for promoting poststroke recovery.

Uterine macrophages and NK cells exhibit population and gene-level changes after implantation but maintain pro-invasive properties

Introduction

Prior to pregnancy, hormonal changes lead to cellular adaptations in the endometrium allowing for embryo implantation. Critical for successful pregnancy establishment, innate immune cells constitute a significant proportion of uterine cells prior to arrival of the embryo and throughout the first trimester in humans and animal models. Abnormal uterine immune cell function during implantation is believed to play a role in multiple adverse pregnancy outcomes. Current work in humans has focused on uterine immune cells present after pregnancy establishment, and limited in vitro models exist to explore unique functions of these cells.

Methods

With single-cell RNA-sequencing (scRNAseq), we comprehensively compared the human uterine immune landscape of the endometrium during the window of implantation and the decidua during the first trimester of pregnancy.

Results

We uncovered global and cell-type-specific gene signatures for each timepoint. Immune cells in the endometrium prior to implantation expressed genes associated with immune metabolism, division, and activation. In contrast, we observed widespread interferon signaling during the first trimester of pregnancy. We also provide evidence of specific inflammatory pathways enriched in pre- and post-implantation macrophages and natural killer (NK) cells in the uterine lining. Using our novel implantation-on-a-chip (IOC) to model human implantation ex vivo, we demonstrate for the first time that uterine macrophages strongly promote invasion of extravillous trophoblasts (EVTs), a process essential for pregnancy establishment. Pre- and post-implantation uterine macrophages promoted EVT invasion to a similar degree as pre- and post-implantation NK cells on the IOC.

Conclusions

This work provides a foundation for further investigation of the individual roles of uterine immune cell subtypes present prior to embryo implantation and during early pregnancy, which will be critical for our understanding of pregnancy complications associated with abnormal trophoblast invasion and placentation.

Bacteria Invade the Brain Following Sterile Intracortical Microelectrode Implantation

Brain-machine interface performance is largely affected by the neuroinflammatory responses resulting in large part from blood-brain barrier (BBB) damage following intracortical microelectrode implantation. Recent findings strongly suggest that certain gut bacterial constituents penetrate the BBB and are resident in various brain regions of rodents and humans, both in health and disease. Therefore, we hypothesized that damage to the BBB caused by microelectrode implantation could amplify dysregulation of the microbiome-gut-brain axis. Here, we report that bacteria, including those commonly found in the gut, enter the brain following intracortical microelectrode implantation in mice implanted with single-shank silicon microelectrodes. Systemic antibiotic treatment of mice implanted with microelectrodes to suppress bacteria resulted in differential expression of bacteria in the brain tissue and a reduced acute inflammatory response compared to untreated controls, correlating with temporary improvements in microelectrode recording performance. Long-term antibiotic treatment resulted in worsening microelectrode recording performance and dysregulation of neurodegenerative pathways. Fecal microbiome composition was similar between implanted mice and an implanted human, suggesting translational findings. However, a significant portion of invading bacteria was not resident in the brain or gut. Together, the current study established a paradigm-shifting mechanism that may contribute to chronic intracortical microelectrode recording performance and affect overall brain health following intracortical microelectrode implantation.

The association between plasma GPNMB and Parkinson's disease and multiple system atrophy

AIMS

Parkinson's disease (PD), as the second most common neurodegenerative disorder, often presents diagnostic challenges in differentiation from other forms of Parkinsonism. Recent studies have reported an association between plasma glycoprotein nonmetastatic melanoma protein B (pGPNMB) and PD.

METHODS

A retrospective study was conducted, comprising 401 PD patients, 111 multiple system atrophy (MSA) patients, 13 progressive supranuclear palsy (PSP) patients and 461 healthy controls from the Chinese Han population, with an assessment of pGPNMB levels.

RESULTS

The study revealed that pGPNMB concentrations were significantly lower in PD and MSA patients compared to controls (area under the receiver operating characteristics curve (AUC) 0.62 and 0.74, respectively, P < 0.0001 for both), but no difference was found in PSP patients compared to controls (P > 0.05). Interestingly, the level of pGPNMB was significantly higher in PD patients than in MSA patients (AUC = 0.63, P < 0.0001). Furthermore, the study explored the association between pGPNMB levels and disease severity in PD and MSA patients, revealing a positive correlation in PD patients but not in MSA patients with both disease severity and cognitive impairment.

CONCLUSION

This study successfully replicated prior findings, demonstrating an association between pGPNMB levels and disease severity, and also identified a correlation with cognitive impairment in PD patients of the Chinese Han population. Additionally, this study is the first to identify a significant difference in pGPNMB levels between MSA, PD, and normal controls. The data provide new evidence supporting the potential role of pGPNMB in the diagnosis and differential diagnosis of Parkinsonism.

Aging impairs cold-induced beige adipogenesis and adipocyte metabolic reprogramming

The energy-burning capability of beige adipose tissue is a potential therapeutic tool for reducing obesity and metabolic disease, but this capacity is decreased by aging. Here, we evaluate the impact of aging on the profile and activity of adipocyte stem and progenitor cells (ASPCs) and adipocytes during the beiging process. We found that aging increases the expression of Cd9 and other fibro-inflammatory genes in fibroblastic ASPCs and blocks their differentiation into beige adipocytes. Fibroblastic ASPC populations from young and aged mice were equally competent for beige differentiation in vitro, suggesting that environmental factors suppress adipogenesis in vivo. Examination of adipocytes by single nucleus RNA-sequencing identified compositional and transcriptional differences in adipocyte populations with age and cold exposure. Notably, cold exposure induced an adipocyte population expressing high levels of de novo lipogenesis (DNL) genes, and this response was severely blunted in aged animals. We further identified natriuretic peptide clearance receptor Npr3, a beige fat repressor, as a marker gene for a subset of white adipocytes and an aging-upregulated gene in adipocytes. In summary, this study indicates that aging blocks beige adipogenesis and dysregulates adipocyte responses to cold exposure and provides a unique resource for identifying cold and aging-regulated pathways in adipose tissue.

Emerging roles of MITF as a crucial regulator of immunity

Microphthalmia-associated transcription factor (MITF), a basic helix-loop-helix leucine zipper transcription factor (bHLH-Zip), has been identified as a melanocyte-specific transcription factor and plays a critical role in melanocyte survival, differentiation, function, proliferation and pigmentation. Although numerous studies have explained the roles of MITF in melanocytes and in melanoma development, the function of MITF in the hematopoietic or immune system-beyond its function in melanin-producing cells-is not yet fully understood. However, there is convincing and increasing evidence suggesting that MITF may play multiple important roles in immune-related cells. Therefore, this review is focused on recent advances in elucidating novel functions of MITF in cancer progression and immune responses to cancer. In particular, we highlight the role of MITF as a central modulator in the regulation of immune responses, as elucidated in recent studies.

Increased Collagen I/Collagen III Ratio Is Associated with Hemorrhage in Brain Arteriovenous Malformations in Human and Mouse

Background: The increase in the collagen I (COL I)/COL III ratio enhances vessel wall stiffness and renders vessels less resistant to blood flow and pressure changes. Activated microglia enhance inflammation-induced fibrosis. Hypotheses: The COL I/COL III ratio in human and mouse brain arteriovenous malformations (bAVMs) is associated with bAVM hemorrhage, and the depletion of microglia decreases the COL I/COL III ratio and hemorrhage. Method: COL I, COL III, and hemorrhages were analyzed in 12 human bAVMs and 6 control brains, and mouse bAVMs induced in three mouse lines with activin receptor-like kinase 1 (n = 7) or endoglin (n = 7) deleted in the endothelial cells or brain focally (n = 5). The controls for the mouse study were no-gene-deleted litter mates. Mouse bAVMs were used to test the relationships between the Col I/Col III ratio and hemorrhage and whether the transient depletion of microglia reduces the Col I/Col III ratio and hemorrhage. Results: The COL I/COL III ratio was higher in the human and mouse bAVMs than in controls. The microhemorrhage in mouse bAVMs was positively correlated with the Col I/Col III ratio. Transient depletion of microglia reduced the Col I/Col III ratio and microhemorrhage. Conclusions: The COL I/COL III ratio in the bAVMs was associated with bAVM hemorrhage. The depletion of microglia reduced the bAVM Col I/Col III ratio and hemorrhage.

GPNMB Modulates Autophagy to Enhance Functional Recovery After Spinal Cord Injury in Rats

Spinal cord injury (SCI) severely affects the quality of life and autonomy of patients, and effective treatments are currently lacking. Autophagy, an essential cellular metabolic process, plays a crucial role in neuroprotection and repair after SCI. Glycoprotein non-metastatic melanoma protein B (GPNMB) has been shown to promote neural regeneration and synapse reconstruction, potentially through the facilitation of autophagy. However, the specific role of GPNMB in autophagy after SCI is still unclear. In this study, we utilized the spinal cord transection method to establish SCI rats model and overexpressed GPNMB using adenoviral vectors. We assessed tissue damage using hematoxylin and eosin (H&E) and Nissl staining, and observed cell apoptosis using TUNEL staining. We evaluated the inflammatory response by measuring inflammatory factors using enzyme-linked immunosorbent assay (ELISA). In addition, we measured reactive oxygen species (ROS) levels using 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA), and assessed oxidative stress levels by measuring malondialdehyde (MDA) and glutathione (GSH) using ELISA. To evaluate autophagy levels, we performed immunofluorescence staining for the autophagy marker Beclin-1 and conducted Western blot analysis for autophagy-related proteins. We also assessed limb recovery through functional evaluation. Meanwhile, we induced cell injury using lipopolysaccharide (LPS) and added an autophagy inhibitor to verify the impact of GPNMB on SCI through autophagy modulation. The results demonstrated that GPNMB alleviated the inflammatory response, reduced oxidative stress levels, inhibited cell apoptosis, and promoted autophagy following SCI. Inhibiting autophagy reversed the effects of GPNMB. These findings suggest that GPNMB promotes neural injury repair after SCI, potentially through attenuating the inflammatory response, reducing oxidative stress, and inhibiting cell apoptosis.

MDSC suppresses T cell antitumor immunity in CAC via GPNMB in a MyD88-dependent manner

BACKGROUND

Myeloid-derived suppressor cells (MDSCs) played an essential role in tumor microenvironment to suppress host antitumor immunity and help cancer cells escape immune surveillance. However, the molecular mechanism behind tumor evasion mediated by MDSCs is not fully understood. Glycoprotein nonmetastatic melanoma protein B (GPNMB) is considered to associate with tumor initiation, metastasis and angiogenesis. Blocking GPNMB function is a potentially valuable therapy for cancer by eliminating GPNMB+MDSCs. Our previous study has proved that blockage the MyD88 signaling with the MyD88 inhibitor, TJ-M2010-5, may completely prevent the development of CAC in mice, accompanying with downregulation of GPNMB mRNA in the inhibitor-treated mice of CAC.

METHODS

We here focus on the underlying the relationship between GPNMB function and MyD88 signaling pathway activation in MDSCs' antitumor activity in CAC.

RESULTS

CAC development in the mouse model is associated with expanded GPNMB+MDSCs by a MyD88-dependent pathway. The GPNMB expression on MDSCs is associated with MyD88 signaling activation. The inhibitory effect of MDSCs on T cell proliferation, activation and antitumor cytotoxicity in CAC is mediated by GPNMB in a MyD8-dependent manner.

CONCLUSION

MyD88 signaling pathway plays an essential role in GPNMB+MDSC-mediated tumor immune escape during CAC development and is a promising focus for revealing the mechanisms of MDSC that facilitate immunosuppression and tumor progression.

Immune response of BV-2 microglial cells is impacted by peroxisomal beta-oxidation

Microglia are crucial for brain homeostasis, and dysfunction of these cells is a key driver in most neurodegenerative diseases, including peroxisomal leukodystrophies. In X-linked adrenoleukodystrophy (X-ALD), a neuroinflammatory disorder, very long-chain fatty acid (VLCFA) accumulation due to impaired degradation within peroxisomes results in microglial defects, but the underlying mechanisms remain unclear. Using CRISPR/Cas9 gene editing of key genes in peroxisomal VLCFA breakdown (Abcd1, Abcd2, and Acox1), we recently established easily accessible microglial BV-2 cell models to study the impact of dysfunctional peroxisomal β-oxidation and revealed a disease-associated microglial-like signature in these cell lines. Transcriptomic analysis suggested consequences on the immune response. To clarify how impaired lipid degradation impacts the immune function of microglia, we here used RNA-sequencing and functional assays related to the immune response to compare wild-type and mutant BV-2 cell lines under basal conditions and upon pro-inflammatory lipopolysaccharide (LPS) activation. A majority of genes encoding proinflammatory cytokines, as well as genes involved in phagocytosis, antigen presentation, and co-stimulation of T lymphocytes, were found differentially overexpressed. The transcriptomic alterations were reflected by altered phagocytic capacity, inflammasome activation, increased release of inflammatory cytokines, including TNF, and upregulated response of T lymphocytes primed by mutant BV-2 cells presenting peptides. Together, the present study shows that peroxisomal β-oxidation defects resulting in lipid alterations, including VLCFA accumulation, directly reprogram the main cellular functions of microglia. The elucidation of this link between lipid metabolism and the immune response of microglia will help to better understand the pathogenesis of peroxisomal leukodystrophies.

Glycoprotein Non-Metastatic Protein B (GPNMB): The Missing Link Between Lysosomes and Obesity

As a result of an unhealthy diet and limited physical activity, obesity has become a widespread pandemic worldwide and is an important predictor for the development of cardiovascular disease. Obesity is often characterized by a pro-inflammatory environment in white adipose tissue (WAT), mainly due to increased macrophage infiltration. These immune cells boost their lipid concentrations by accumulating the content of dying adipocytes. As the lysosome is highly involved in lipid handling, the progressive lipid accumulation may result in lysosomal stress and a metabolic shift. Recent studies have identified glycoprotein non-metastatic melanoma protein B (GPNMB) as a novel marker of inflammatory diseases. GPNMB is a type I transmembrane protein on the cell surface of various cell types, such as macrophages, dendritic cells, osteoblasts, and microglia, from which it can be proteolytically cleaved into a soluble molecule. It is induced by lysosomal stress via microphthalmia-associated transcription factor and thus has been found to be upregulated in many lysosomal storage disorders. In addition, a clear connection between GPNMB and obesity was recently established. GPNMB was shown to have protective and anti-inflammatory effects in most cases, preventing the progression of obesity-related metabolic disorders. In contrast, soluble GPNMB likely has the opposite effect and promotes lipogenesis in WAT. This review aims to summarize and clarify the role of GPNMB in the progression of obesity and to highlight its potential use as a biomarker for lipid-associated disorders.

GPNMB Ameliorates Neuroinflammation Via the Modulation of AMPK/NFκB Signaling Pathway After SAH in Mice

Glycoprotein non-metastatic melanoma protein B (GPNMB) got its name from the first discovery in a cell line of non-metastatic melanoma. Later studies found that GPNMB is widely expressed in various tissues and cells of the human body, most abundant in neural tissue, epithelial tissue, bone tissue, and monocyte-macrophage system. GPNMB has been shown to have anti-inflammatory effects in a variety of neurological diseases, however, it has not been reported in subarachnoid hemorrhage (SAH). Male CD-1 mice were used and intra-arterial puncture method was applied to establish the SAH model. Exogenous recombinant GPNMB (rGPNMB) was injected intracerebroventricularly 1 h after SAH. SAH grading, brain edema and blood-brain barrier (BBB) integrity were quantified, and neurobehavioral tests were performed to evaluate the effect of GPNMB on the outcome. Dorsomorphin, the selective inhibitor on AMPK was introduced to study the downstream signaling through which the GPNMB works. Furthermore, western blot, immunofluorescence staining and ELISA were utilized to confirm the signaling. After SAH, GPNMB expression increased significantly as a result of the inflammatory response. GPNMB was expressed extensively in mouse microglia, astrocytes and neurons. The administration of rGPNMB could alleviate brain edema, restore BBB integrity and improve the neurological outcome of mice with SAH. GPNMB treatment significantly magnified the expression of p-AMPK while p-NFκB, IL-1β, IL-6 and TNF-α were suppressed; in the meantime, the combined administration of GPNMB and AMPK inhibitor could decrease the intensity of p-AMPK and reverse the quantity of p-NFκB and the above inflammatory cytokines. GPNMB has the potential of ameliorating the brain edema and neuroinflammation, protecting the BBB and improving the neurological outcome, possibly via the AMPK/NFκB signaling pathway.

Microglial Transcriptional Signatures in the Central Nervous System: Toward A Future of Unraveling Their Function in Health and Disease

Microglia, the resident immune cells of the central nervous system (CNS), are primarily derived from the embryonic yolk sac and make their way to the CNS during early development. They play key physiological and immunological roles across the life span, throughout health, injury, and disease. Recent transcriptomic studies have identified gene transcript signatures expressed by microglia that may provide the foundation for unprecedented insights into their functions. Microglial gene expression signatures can help distinguish them from macrophage cell types to a reasonable degree of certainty, depending on the context. Microglial expression patterns further suggest a heterogeneous population comprised of many states that vary according to the spatiotemporal context. Microglial diversity is most pronounced during development, when extensive CNS remodeling takes place, and following disease or injury. A next step of importance for the field will be to identify the functional roles performed by these various microglial states, with the perspective of targeting them therapeutically.

Omics profile of iPSC-derived astrocytes from Progressive Supranuclear Palsy (PSP) patients

INTRODUCTION

Progressive Supranuclear Palsy (PSP) is a neurodegenerative tauopathy and, to date, the pathophysiological mechanisms in PSP that lead to Tau hyperphosphorylation and neurodegeneration are not clear. In some brain areas, Tau pathology in glial cells appears to precede Tau aggregation in neurons. The development of a model using astrocyte cell lines derived from patients has the potential to identify molecules and pathways that contribute to early events of neurodegeneration. We developed a model of induced pluripotent stem cells (iPSC)-derived astrocytes to investigate the pathophysiology of PSP, particularly early events that might contribute to Tau hyperphosphorylation, applying omics approach to detect differentially expressed genes, metabolites, and proteins, including those from the secretome.

METHODS

Skin fibroblasts from PSP patients (without MAPT mutations) and controls were reprogrammed to iPSCs, further differentiated into neuroprogenitor cells (NPCs) and astrocytes. In the 5th passage, astrocytes were harvested for total RNA sequencing. Intracellular and secreted proteins were processed for proteomics experiments. Metabolomics profiling was obtained from supernatants only.

RESULTS

We identified hundreds of differentially expressed genes. The main networks were related to cell cycle re-activation in PSP. Several proteins were found exclusively secreted by the PSP group. The cellular processes related to the cell cycle and mitotic proteins, TriC/CCT pathway, and redox signaling were enriched in the secretome of PSP. Moreover, we found distinct sets of metabolites between PSP and controls.

CONCLUSION

Our iPSC-derived astrocyte model can provide distinct molecular signatures for PSP patients and it is useful to elucidate the initial stages of PSP pathogenesis.

Cytokine Profiling in Human iPSC-Derived Dopaminergic Neuronal and Microglial Cultures

Aside from the degeneration of dopaminergic neurons, inflammation is a key component in the movement disorder Parkinson's disease (PD). Microglia activation as well as elevated cytokine levels were observed in the brains of PD patients, but the specific role of microglia in the disease process is unknown. Here, we generate human cellular models by differentiating iPSCs into dopaminergic neurons and microglia. We combine these cells in co-culture to perform cytokine profiling, representing the final functional outcome of various signaling pathways. For this, we used unstimulated conditions and treatment with inflammatory stressors. Importantly, only co-cultures but not the monocultures responded to IL-1β treatment suggesting co-culture-related crosstalk. Moreover, we identified the main types of released cytokines and chemokines in this model system and found a preference for the activation of the chemotaxis pathway in response to all treatments, which informs future studies on the cell-type-specific reaction to inflammatory stimulation. Finally, we detected protein level changes in PD risk factor GPNMB upon stress in microglia, further confirming the link between PD-associated genes and inflammation in human-derived cellular models.

Glycoprotein non-metastatic melanoma protein B expression correlates with the prognosis of acute liver injury/failure

Background: Glycoprotein non-metastatic melanoma protein B (GPNMB) is expressed in macrophages during recovery from acute liver injury (ALI) in carbon tetrachloride (CCl4)-induced liver injury model mice. In this retrospective study, we assessed whether GPNMB levels in the serum and injured liver correlate with liver injury severity and prognosis in patients with ALI or acute liver failure (ALF). Methods: The study involved 56 patients with ALI or ALF who visited the Kagoshima University Hospital. Serum GPNMB level was measured over time, and the localization, proportion, origin, and phenotype of GPNMB-expressing cells in the injured liver were assessed. Finally, the phenotypes of human monocyte-derived macrophages and peripheral blood mononuclear cells (PBMCs) of patients with ALI and ALF were analyzed. Results: Peak GPNMB levels were significantly higher in patients with ALF and hepatic encephalopathy (HE), as well as in those who underwent liver transplantation or died, than in others. The peak GPNMB level correlated with prothrombin activity, prothrombin time-international normalized ratio, Model for End-stage Liver Disease score, and serum hepatocyte growth factor level. GPNMB was expressed in CD68-positive macrophages, and its level increased with the severity of liver injury. The macrophages showed the same polarization as M2c macrophages induced with interleukin-10 from human monocytes. Moreover, PBMCs from patients with ALF exhibited an immunosuppressive phenotype. Conclusion: We found that GPNMB levels in the serum and injured liver, which increased in patients with ALF, especially in those with HE, correlated with the severity of liver injury and prognosis of ALI and ALF. Moreover, GPNMB-positive macrophages exhibited the M2c phenotype. Our results indicate that persistently high GPNMB levels may be a prognostic marker in patients with ALI and ALF.

Time course of western diet (WD) induced nonalcoholic steatohepatitis (NASH) in female and male Ldlr-/- mice

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a global health problem. Identification of factors contributing to the onset and progression of NAFLD have the potential to direct novel strategies to combat NAFLD.

METHODS

We examined the time course of western diet (WD)-induced NAFLD and its progression to nonalcoholic steatohepatitis (NASH) in age-matched female and male Ldlr-/- mice, with time-points at 1, 4, 8, 20 and 40 weeks on the WD. Controls included Ldlr-/- mice maintained on a purified low-fat diet (LFD) for 1 and 40 weeks. The approach included quantitation of anthropometric, plasma and liver markers of disease, plus hepatic histology, lipids, oxylipins, gene expression and selected metabolites.

RESULTS

One week of feeding the WD caused a significant reduction in hepatic essential fatty acids (EFAs: 18:2, ω6, 18:3, ω3) which preceded the decline in many C20-22 ω3 and ω6 polyunsaturated fatty acids (PUFA) and PUFA-derived oxylipins after 4 weeks on the WD. In addition, expression of hepatic inflammation markers (CD40, CD44, Mcp1, Nlrp3, TLR2, TLR4, Trem2) increased significantly in both female & male mice after one week on the WD. These markers continued to increase over the 40-week WD feeding study. WD effects on hepatic EFA and inflammation preceded all significant WD-induced changes in body weight, insulin resistance (HOMA-IR), oxidative stress status (GSH/GSSG ratio) and histological and gene expression markers of macrosteatosis, extracellular matrix remodeling and fibrosis.

CONCLUSIONS

Our findings establish that feeding Ldlr-/- mice the WD rapidly lowered hepatic EFAs and induced key inflammatory markers linked to NASH. Since EFAs have an established role in inflammation and hepatic inflammation plays a major role in NASH, we suggest that early clinical assessment of EFA status and correcting EFA deficiencies may be useful in reducing NASH severity.

No Correlation between Plasma GPNMB Levels and Multiple System Atrophy in Chinese Cohorts

BACKGROUND

Glycoprotein nonmetastatic melanoma protein B (GPNMB) has been demonstrated to mediate pathogenicity in Parkinson's disease (PD) through interactions with α-synuclein, and plasma GPNMB tended to be a novel biomarker for PD.

OBJECTIVE

The goal of this study was to investigate whether plasma GPNMB could act as a potential biomarker for the clinical diagnosis and severity monitoring of multiple system atrophy (MSA), another typical synucleinopathy.

METHODS

Plasma GPNMB levels in patients with MSA, patients with PD, and healthy control subjects (HCs) were quantified using enzyme-linked immunosorbent assays.

RESULTS

A total of 204 patients with MSA, 65 patients with PD, and 207 HCs were enrolled. The plasma GPNMB levels in patients with MSA were similar to those in HCs (P = 0.251) but were significantly lower than those in patients with PD (P = 0.003). Moreover, there was no significant correlation detected between the plasma GPNMB levels and disease severity scores of patients with MSA.

CONCLUSIONS

No evidence was detected for the biomarker potential of plasma GPNMB in MSA. © 2023 International Parkinson and Movement Disorder Society.

A microglial activity state biomarker panel differentiates FTD-granulin and Alzheimer's disease patients from controls

BACKGROUND

With the emergence of microglia-modulating therapies there is an urgent need for reliable biomarkers to evaluate microglial activation states.

METHODS

Using mouse models and human induced pluripotent stem cell-derived microglia (hiMGL), genetically modified to yield the most opposite homeostatic (TREM2-knockout) and disease-associated (GRN-knockout) states, we identified microglia activity-dependent markers. Non-targeted mass spectrometry was used to identify proteomic changes in microglia and cerebrospinal fluid (CSF) of Grn- and Trem2-knockout mice. Additionally, we analyzed the proteome of GRN- and TREM2-knockout hiMGL and their conditioned media. Candidate marker proteins were tested in two independent patient cohorts, the ALLFTD cohort (GRN mutation carriers versus non-carriers), as well as the proteomic data set available from the EMIF-AD MBD study.

RESULTS

We identified proteomic changes between the opposite activation states in mouse microglia and CSF, as well as in hiMGL cell lysates and conditioned media. For further verification, we analyzed the CSF proteome of heterozygous GRN mutation carriers suffering from frontotemporal dementia (FTD). We identified a panel of six proteins (FABP3, MDH1, GDI1, CAPG, CD44, GPNMB) as potential indicators for microglial activation. Moreover, we confirmed three of these proteins (FABP3, GDI1, MDH1) to be significantly elevated in the CSF of Alzheimer's (AD) patients. Remarkably, each of these markers differentiated amyloid-positive cases with mild cognitive impairment (MCI) from amyloid-negative individuals.

CONCLUSIONS

The identified candidate proteins reflect microglia activity and may be relevant for monitoring the microglial response in clinical practice and clinical trials modulating microglial activity and amyloid deposition. Moreover, the finding that three of these markers differentiate amyloid-positive from amyloid-negative MCI cases in the AD cohort suggests that these proteins associate with a very early immune response to seeded amyloid. This is consistent with our previous findings in the Dominantly Inherited Alzheimer's Disease Network (DIAN) cohort, where soluble TREM2 increases as early as 21 years before symptom onset. Moreover, in mouse models for amyloidogenesis, seeding of amyloid is limited by physiologically active microglia further supporting their early protective role. The biological functions of some of our main candidates (FABP3, CD44, GPNMB) also further emphasize that lipid dysmetabolism may be a common feature of neurodegenerative disorders.

Epigenetic regulation of Parkinson's disease risk variant GPNMB cg17274742 methylation by sex and exercise from Taiwan Biobank

Background

Parkinson's disease (PD) is a complex neurodegenerative disease with an elusive etiology that involves the interaction between genetic, behavioral, and environmental factors. Recently, epigenetic modifications, particularly DNA methylation, have been recognized to play an important role in the onset of PD. Glycoprotein non-metastatic melanoma protein B (GPNMB), a type I transmembrane protein crucial for immune cell activation and maturation, has emerged as a potential biomarker for the risk of PD. This research aims to investigate the influence of exercise and gender on the regulation of methylation levels of GPNMB cg17274742 in individuals.

Methods

We analyze data from 2,474 participants in the Taiwan Biobank, collected from 2008 and 2016. Methylation levels at the GPNMB cg17274742 CpG site were measured using Illumina Infinium MethylationEPIC beads. After excluding individuals with incomplete data or missing information on possible risk factors, our final analysis included 1,442 participants. We used multiple linear regression models to assess the association between sex and exercise with adjusted levels of GPNMB cg17274742 for age, BMI, smoking, drinking, coffee consumption, serum uric acid levels, and hypertension.

Results

Our results demonstrated that exercise significantly influenced the methylation levels of GPNMB cg17274742 in males (β = -0.00242; p = 0.0026), but not in females (β = -0.00002362; p = 0.9785). Furthermore, male participants who exercised showed significantly lower levels of methylation compared to the reference groups of the female and non-exercising reference groups (β = -0.00357; p = 0.0079). The effect of the interaction between gender and exercise on the methylation of GPNMB cg17274742 was statistically significant (p = 0.0078).

Conclusion

This study suggests that gender and exercise can modulate GPNMB cg17274742, with hypomethylation observed in exercise men. More research is needed to understand the underlying mechanisms and implications of these epigenetic changes in the context of risk and prevention strategies.

Barnacle-Inspired Wet Tissue Adhesive Hydrogels with Inherent Antibacterial Properties for Infected Wound Treatment

Currently, antibiotics are the most common treatment for bacterial infections in clinical practice. However, with the abuse of antibiotics and the emergence of drug-resistant bacteria, the use of antibiotics has faced an unprecedented challenge. It is imminent to develop nonantibiotic antimicrobial agents. Based on the cation-π structure of barnacle cement protein, a polyphosphazene-based polymer poly[(N,N-dimethylethylenediamine)-g-(N,N,N,N-dimethylaminoethyl p-ammonium bromide (ammonium bromide)-g-(N,N,N,N-dimethylaminoethyl acetate ethylammonium bromide)] (PZBA) with potential adhesion and inherent antibacterial properties was synthesized, and a series of injectable antibacterial adhesive hydrogels (PZBA-PVA) were prepared by cross-linking with poly(vinyl alcohol) (PVA). PZBA-PVA hydrogels showed good biocompatibility, and the antibacterial rate of the best-performed hydrogel reached 99.81 ± 0.04% and 98.80 ± 2.16% against Staphylococcus aureus and Escherichia coli within 0.5 h in vitro, respectively. In the infected wound model, the healing rate of the PZBA-PVA-treated group was significantly higher than that of the Tegaderm film group due to the fact that the hydrogel suppressed inflammatory responses and modulated the infiltration of immune cells. Moreover, the wound healing mechanism of the PZBA-PVA hydrogel was further evaluated by real-time polymerase chain reaction and total RNA sequencing. The results indicated that the process of hemostasis and tissue development was prompted and the inflammatory and immune responses were suppressed to accelerate wound healing. Overall, the PZBA-PVA hydrogel is shown to have the potential for infected wound healing application.

Translatome analysis reveals microglia and astrocytes to be distinct regulators of inflammation in the hyperacute and acute phases after stroke

Neuroinflammation is a hallmark of ischemic stroke, which is a leading cause of death and long-term disability. Understanding the exact cellular signaling pathways that initiate and propagate neuroinflammation after stroke will be critical for developing immunomodulatory stroke therapies. In particular, the precise mechanisms of inflammatory signaling in the clinically relevant hyperacute period, hours after stroke, have not been elucidated. We used the RiboTag technique to obtain microglia and astrocyte-derived mRNA transcripts in a hyperacute (4 h) and acute (3 days) period after stroke, as these two cell types are key modulators of acute neuroinflammation. Microglia initiated a rapid response to stroke at 4 h by adopting an inflammatory profile associated with the recruitment of immune cells. The hyperacute astrocyte profile was marked by stress response genes and transcription factors, such as Fos and Jun, involved in pro-inflammatory pathways such as TNF-α. By 3 days, microglia shift to a proliferative state and astrocytes strengthen their inflammatory response. The astrocyte pro-inflammatory response at 3 days is partially driven by the upregulation of the transcription factors C/EBPβ, Spi1, and Rel, which comprise 25% of upregulated transcription factor-target interactions. Surprisingly, few sex differences across all groups were observed. Expression and log2 fold data for all sequenced genes are available on a user-friendly website for researchers to examine gene changes and generate hypotheses for stroke targets. Taken together, our data comprehensively describe the microglia and astrocyte-specific translatome response in the hyperacute and acute period after stroke and identify pathways critical for initiating neuroinflammation.

Differential effects of sugar and fat on adipose tissue inflammation

Obese individuals experience low grade inflammation initiated within their adipose tissue. However, the early events that lead to the release of these inflammatory factors from adipose tissue are poorly characterized. To separate glucose effects from lipid effects on adipose tissue, we used an adipose-specific TXNIP knockout model where excess basal glucose influx into adipocytes led to modest increase in adiposity without using high fat diet. We found an uncoupling of two events that are generally presumed to be coregulated: (1) an increase of adipose tissue macrophage (ATM) number; and (2) pro-inflammatory activation of ATMs. These two events are associated with different triggering signals: elevated free fatty acids output and extracellular matrix remodeling with increased ATM number, whereas decreased adiponectin level with activated ATM. This separation reflects non-overlapping pathways regulated by glucose and lipids in adipocytes, and neither group alone is sufficient to elicit the full inflammatory response in adipose tissue.