Real-Time Imaging Assessment of Stress-Induced Vascular Inflammation Using Heartbeat-Synchronized Motion Compensation.

BACKGROUND: Chronic mental stress accelerates atherosclerosis through complicated neuroimmune pathways, needing for advanced imaging techniques to delineate underlying cellular mechanisms. While histopathology, ex vivo imaging, and snapshots of in vivo images offer promising evidence, they lack the ability to capture real-time visualization of blood cell dynamics within pulsatile arteries in longitudinal studies. METHODS: An electrically tunable lens was implemented in intravital optical microscopy, synchronizing the focal plane with heartbeats to follow artery movements. ApoE-/- mice underwent 2 weeks of restraint stress before baseline imaging followed by 2 weeks of stress exposure in the longitudinal imaging, while nonstressed mice remained undisturbed. The progression of vascular inflammation was assessed in the carotid arteries through intravital imaging and histological analyses. RESULTS: A 4-fold reduction of motion artifact, assessed by interframe SD, and an effective temporal resolution of 25.2 Hz were achieved in beating murine carotid arteries. Longitudinal intravital imaging showed chronic stress led to a 6.09-fold (P=0.017) increase in myeloid cell infiltration compared with nonstressed mice. After 3 weeks, we observed that chronic stress intensified vascular inflammation, increasing adhered myeloid cells by 2.45-fold (P=0.031), while no significant changes were noted in nonstressed mice. Microcirculation imaging revealed increased circulating, rolling, and adhered cells in stressed mice's venules. Histological analysis of the carotid arteries confirmed the in vivo findings that stress augmented plaque area, myeloid cell and macrophage accumulation, and necrotic core volume while reducing fibrous cap thickness indicating accelerated plaque formation. We visualized the 3-dimensional structure of the carotid artery and 4-dimensional dynamics of the venules in the cremaster muscle. CONCLUSIONS: Dynamic focusing motion compensation intravital microscopy enabled subcellular resolution in vivo imaging of blood cell dynamics in beating arteries under chronic restraint stress in real time. This novel technique emphasizes the importance of advanced in vivo imaging for understanding cardiovascular disease.

Periodontitis and Diabetes Differentially Affect Inflammation in Obesity.

Periodontitis (PD) potentiates systemic inflammatory diseases and fuels a feed-forward loop of pathogenic inflammation in obesity and type 2 diabetes (T2D). Published work in this area often conflates obesity with obesity-associated T2D; thus, it remains unclear whether PD similarly affects the inflammatory profiles of these 2 distinct systemic diseases. We collected peripheral blood mononuclear cells (PBMCs) from cross-sectionally recruited subjects to estimate the ability of PD to affect cytokine production in human obesity and/or T2D. We analyzed 2 major sources of systemic inflammation: T cells and myeloid cells. Bioplex quantitated cytokines secreted by PBMCs stimulated with T cell- or myeloid-targeting activators, and we combinatorially analyzed outcomes using partial least squares discriminant analysis. Our data show that PD significantly shifts peripheral T cell- and myeloid-generated inflammation in obesity. PD also changed myeloid- but not T cell-generated inflammation in T2D. T2D changed inflammation in samples from subjects with PD, and PD changed inflammation in samples from subjects with T2D, consistent with the bidirectional relationship of inflammation between these 2 conditions. PBMCs from T2D subjects with stage IV PD produced lower amounts of T cell and myeloid cytokines compared with PBMCs from T2D subjects with stage II to III PD. We conclude that PD and T2D affect systemic inflammation through overlapping but nonidentical mechanisms in obesity, indicating that characterizing both oral and metabolic status (beyond obesity) is critical for identifying mechanisms linking PD to systemic diseases such as obesity and T2D. The finding that stage IV PD cells generate fewer cytokines in T2D provides an explanation for the paradoxical findings that the immune system can appear activated or suppressed in PD, given that many studies do not report PD stage. Finally, our data indicate that a focus on multiple cellular sources of cytokines will be imperative to clinically address the systemic effects of PD in people with obesity.

Development of human innate immune responses in a humanized mouse model expressing four human myelopoiesis transgenes.

Background: Dysregulated innate immune responses underlie multiple inflammatory diseases, but clinical translation of preclinical innate immunity research in mice is hampered by the difficulty of studying human inflammatory reactions in an in vivo context. We therefore sought to establish in vivo human inflammatory responses in NSG-QUAD mice that express four human myelopoiesis transgenes to improve engraftment of a human innate immune system. Methods: We reconstituted NSG-QUAD mice with human hematopoietic stem and progenitor cells (HSPCs), after which we evaluated human myeloid cell development and subsequent human responses to systemic and local lipopolysaccharide (LPS) challenges. Results: NSG-QUAD mice already displayed engraftment of human monocytes, dendritic cells and granulocytes in peripheral blood, spleen and liver at 6 weeks after HSPC reconstitution, in which both classical, intermediate and non-classical monocytes were present. These huNSG-QUAD mice responded to intraperitoneal and intranasal LPS challenges with production of NF-κB-dependent human cytokines, a human type I interferon response, as well as inflammasome-mediated production of human IL-1ß and IL-18. The latter were specifically abrogated by the NLRP3 inhibitor MCC950, while LPS-induced human monocyte death was not altered. Besides providing proof-of-principle for small molecule testing of human inflammatory reactions in huNSG-QUAD mice, this observation suggests that LPS-induced in vivo release of human NLRP3 inflammasome-generated cytokines occurs in a cell death-independent manner. Conclusion: HuNSG-QUAD mice are competent for the NF-κB, interferon and inflammasome effectors of human innate immunity, and can thus be utilized to investigate signaling mechanisms and pharmacological targeting of human inflammatory responses in an in vivo setting.

Alzheimer's disease clinical variants show distinct neuroinflammatory profiles with neuropathology.

AIMS: Although the neuroanatomical distribution of tau and amyloid-ß is well studied in Alzheimer's disease (AD) (non)-amnestic clinical variants, that of neuroinflammation remains unexplored. We investigate the neuroanatomical distribution of activated myeloid cells, astrocytes, and complement alongside amyloid-ß and phosphorylated tau in a clinically well-defined prospectively collected AD cohort. METHODS: Clinical variants were diagnosed antemortem, and brain tissue was collected post-mortem. Typical AD (n = 10), behavioural/dysexecutive AD (n = 6), posterior cortical atrophy (PCA) AD (n = 3), and controls (n = 10) were neuropathologically assessed for AD neuropathology, concurrent pathology including Lewy body disease, limbic-predominant age-related TDP-43 encephalopathy neuropathologic change (LATE-NC), and vascular pathology. For quantitative assessment, we analysed the corticolimbic distribution of phosphorylated tau, amyloid-ß, CD68, MHC-II, C4b, and glial fibrillary acidic protein (GFAP) using digital pathology. RESULTS: Phosphorylated tau was distinctly distributed in each variant. In all variants, amyloid-ß was neocortical-dominant, with a notable increase in the middle frontal cortex of behavioural/dysexecutive AD. Typical AD and PCA AD had no concurrent Lewy body disease, whereas three out of six cases with behavioural/dysexecutive AD did. LATE-NC stage >0 was observed in three AD cases, two typical AD (stage 1/3), and one behavioural/dysexecutive AD (stage 2/3). Vascular pathology was present in each variant. In typical AD, CD68 and MHC-II were hippocampal-dominant. In behavioural/dysexecutive AD, C4b was elevated in the middle frontal and inferior parietal cortex. In PCA AD, MHC-II was increased in the fusiform gyrus, and GFAP in parietal cortices. Correlations between AD neuropathology and neuroinflammation were distinct within variants. CONCLUSIONS: Our data suggests that different involvement of neuroinflammation may add to clinical heterogeneity in AD, which has implications for neuroinflammation-based biomarkers and future therapeutics.

Multiomics analyses decipher intricate changes in the cellular and metabolic landscape of steatotic livers upon dietary restriction and sleeve gastrectomy.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a chronic, progressive liver disease that encompasses a spectrum of steatosis, steatohepatitis (or MASH), and fibrosis. Evidence suggests that dietary restriction (DR) and sleeve gastrectomy (SG) can lead to remission of hepatic steatosis and inflammation through weight loss, but it is unclear whether these procedures induce distinct metabolic or immunological changes in MASLD livers. This study aims to elucidate the intricate hepatic changes following DR, SG or sham surgery in rats fed a high-fat diet as a model of obesity-related MASLD, in comparison to a clinical cohort of patients undergoing SG. Single-cell and single-nuclei transcriptome analysis, spatial metabolomics, and immunohistochemistry revealed the liver landscape, while circulating biomarkers were measured in serum samples. Artificial intelligence (AI)-assisted image analysis characterized the spatial distribution of hepatocytes, myeloid cells and lymphocytes. In patients and experimental MASLD rats, SG improved body mass index, circulating liver injury biomarkers and triglyceride levels. Both DR and SG attenuated liver steatosis and fibrosis in rats. Metabolism-related genes (Ppara, Cyp2e1 and Cyp7a1) were upregulated in hepatocytes upon DR and SG, while SG broadly upregulated lipid metabolism on cholangiocytes, monocytes, macrophages, and neutrophils. Furthermore, SG promoted restorative myeloid cell accumulation in the liver not only ameliorating inflammation but activating liver repair processes. Regions with potent myeloid infiltration were marked with enhanced metabolic capacities upon SG. Additionally, a disruption of periportal hepatocyte functions was observed upon DR. In conclusion, this study indicates a dynamic cellular crosstalk in steatotic livers of patients undergoing SG. Notably, PPARα- and gut-liver axis-related processes, and metabolically active myeloid cell infiltration indicate intervention-related mechanisms supporting the indication of SG for the treatment of MASLD.

Cell-Specific Contribution of IL4 Receptor α Signaling Shapes the Overall Manifestation of Allergic Airway Disease.

IL-4 and IL-13 play a critical role in allergic asthma pathogenesis via their common receptor, i.e., IL4Rα. However, the cell-specific role of IL4Rα in mixed allergens (MA)-induced allergic asthma has remained unclear. Therefore, we aimed to identify the cell-specific contribution of IL4Rα signaling in the manifestation of various pathological outcomes in mice with allergic airway disease. We compared MA-induced pathological outcomes between hematopoietic progenitor cells (HPCs)- or non-HPCs-specific IL4Rα-deficient chimera, myeloid cell-specific IL4Rα-deficient (LysMcre+/+/IL4Rαfl/fl), and airway epithelial cell-specific IL4Rα-deficient (CCSP-Cre+ /IL4Rαfl/fl) mice. Chimeric mice with systemic IL4Rα sufficiency displayed hallmark features of allergic asthma, including eosinophilic and lymphocytic infiltration, type 2 (Th2) cytokine/chemokine production, IgE production, and lung pathology. These features were markedly reduced in chimeric mice with systemic IL4Rα deficiency. Non-HPCs-specific IL4Rα-deficient mice displayed typical inflammatory features of allergic asthma but with markedly reduced mucous cell metaplasia (MCM). Deletion of IL4Rα signaling on airway epithelial cells, a subpopulation within the non-HPC lineage, resulted in almost complete absence of MCM. In contrast, all features of allergic asthma except for MCM and mucin production were mitigated in HPCs-specific IL4Rα-deficient chimeric mice. Deleting IL4Rα signaling in myeloid cells, a subpopulation within the HPC lineage, significantly alleviated MA-induced allergic airway inflammatory responses, but similar to the HPCs-specific IL4Rα-deficient chimeric mice, these mice showed significant MCM and mucin production. Our findings demonstrate that the differential allergen responsiveness seen in mice with HPCs-specific and non-HPCs-specific IL4Rα deficiency is predominantly driven by the absence of IL4Rα in myeloid cells and airway epithelial cells, respectively. Our findings also highlight distinct and mutually exclusive roles of IL4Rα signaling in mediating pathological outcomes within the myeloid and airway epithelial cell compartments.

A comprehensive and longitudinal evaluation of the different populations of lymphoid and myeloid cells in the peripheral blood of patients treated with chemoradiotherapy for head and neck cancer.

BACKGROUND: Immunotherapy provided significant survival benefits for recurrent and metastatic patients with head and neck cancer. These improvements could not be reproduced in patients treated with curative-intent chemoradiotherapy (CRT) and the optimal radio-immunotherapy (RIT) concepts have yet to be designed. Exploration and analysis of the pre-therapeutic immune status of these patients and the changes occurring during the treatment course could be crucial in rationally designing future combined treatments. METHODS: Blood samples were collected from a cohort of 25 head and neck cancer patients treated with curative-intended (C)-RT prior to therapy, after the first week of treatment, and three months after treatment completion. Peripheral blood mononuclear cells (PBMCs) or all nucleated blood cells were isolated and analyzed via flow cytometry. RESULTS: At baseline, patients showed reduced monocyte and lymphocyte counts compared to healthy individuals. Although overall CD8+ T-cell frequencies were reduced, the proportion of memory subsets were increased in patients. Radiotherapy (RT) treatment led to a further increase in CD8+ effector memory T-cells. Among myeloid populations, tumor-promoting subsets became less abundant after RT, in favor of pro-inflammatory cells. CONCLUSION: The present study prospectively demonstrated a complex interplay and distinct longitudinal changes in the composition of lymphocytic and myeloid populations during curative (C)-RT of head and neck cancer. Further validation of this method in a larger cohort could allow for better treatment guidance and tailored incorporation of immunotherapies (IT) in the future.

Engaging natural regulatory myeloid cells to restrict T-cell hyperactivation-induced liver inflammation via extracellular vesicle-mediated purine metabolism regulation.

Rationale: Dysregulated T-cell immune response-mediated inflammation plays critical roles in the pathology of diverse liver diseases, but the underlying mechanism of liver immune homeostasis control and the specific therapies for limiting T-cell overactivation remain unclear. Methods: The metabolic changes in concanavalin A (ConA) mice and autoimmune hepatitis (AIH) patients and their associations with liver injury were analyzed. The expression of purine catabolism nucleases (e.g., CD39 and CD73) on liver cells and immune cells was assessed. The effects of MCregs and their extracellular vesicles (EVs) on CD4+ T-cell overactivation and the underlying mechanism were also explored. Results: Our findings revealed significant alterations in purine metabolism in ConA mice and AIH patients, which correlated with liver injury severity and therapeutic response. CD39 and CD73 were markedly upregulated on CD11b+Gr-1+ MCs under liver injury conditions. The naturally expanded CD39+CD73+Gr-1highCD11b+ MCreg subset during early liver injury effectively suppressed CD4+ T-cell hyperactivation and liver injury both in vitro and in vivo. Mechanistically, MCregs released CD73high EVs, which converted extracellular AMP to immunosuppressive metabolites (e.g., adenosine and inosine), activating the cAMP pathway and inhibiting glycolysis and cytokine secretion in activated CD4+ T cells. Conclusions: This study provides insights into the mechanism controlling immune homeostasis during the early liver injury phase and highlights that MCreg or MCreg-EV therapy may be a specific strategy for preventing diverse liver diseases induced by T-cell overactivation.

Role of myeloid cells in mediating the effects of lipids on ulcerative colitis.

Objective: To evaluate the causal relationship between lipids and ulcerative colitis (UC) through Mendelian Randomization (MR), and to further investigate the involvement of immune cells in mediating this process. Methods: Utilizing summary statistics from genome-wide association studies (GWAS) of individuals with European ancestry, we analyzed the causal link between 179 lipid types and UC (2,569 UC cases and 453,779 controls) through Two-sample Mendelian randomization (2SMR) and Bayesian-weighted MR (BWMR). Based on this, a mediation screening of 731 immune cell phenotypes was conducted to identify exposure and mediator factors. Lastly, the role and proportion of immune cells in mediating the causal effects of lipids on UC were assessed via reverse MR (RMR) and two-step MR. Results: The results of MR showed that there was a causal relationship between the six genetically predicted lipid types and UC (P <0.05), and the four immune cell phenotypes were identified as mediators of the association between lipids and UC. Notably, Phosphatidylcholine (PC) (16:0_0:0) served as the exposure factor, and myeloid cells CD11b on CD33+ HLA DR+ CD14dim acted as the mediator. Mediation analysis showed that CD11b on CD33+ HLA DR+ CD14dim had a mediation effect of -0.0205 between PC (16:0_0:0) and UC, with the mediation effect ratio at 15.38%. Conclusion: Our findings elucidate the causal effect of lipids on UC and identify the significant mediating role of myeloid cells CD11b on CD33+ HLA DR+ CD14dim in regulating UC through PC (16:0_0:0), offering new pathways and strategies for UC clinical treatment.

Lupus-prone NZM2328 mice exhibit enhanced UV-induced myeloid cell recruitment and activation in a type I interferon dependent manner.

Though the exact causes of systemic lupus erythematosus (SLE) remain unknown, exposure to ultraviolet (UV) light is one of the few well-known triggers of cutaneous inflammation in SLE. However, the precise cell types which contribute to the early cutaneous inflammatory response in lupus, and the ways that UV dosing and interferons modulate these findings, have not been thoroughly dissected. Here, we explore these questions using the NZM2328 spontaneous murine model of lupus. In addition, we use iNZM mice, which share the NZM2328 background but harbor a whole-body knockout of the type I interferon (IFN) receptor, and wild-type BALB/c mice. 10-13-week-old female mice of each strain were treated with acute (300 mJ/cm2 x1), chronic (100 mJ/cm2 daily x5 days), or no UVB, and skin was harvested and processed for bulk RNA sequencing and flow cytometry. We identify that inflammatory pathways and gene signatures related to myeloid cells - namely neutrophils and monocyte-derived dendritic cells - are a shared feature of the acute and chronic UVB response in NZM skin greater than iNZM and wild-type skin. We also verify recruitment and activation of these cells by flow cytometry in both acutely and chronically irradiated NZM and WT mice and demonstrate that these processes are dependent on type I IFN signaling. Taken together, these data indicate a skewed IFN-driven inflammatory response to both acute and chronic UVB exposure in lupus-prone skin dominated by myeloid cells, suggesting both the importance of type I IFNs and myeloid cells as therapeutic targets for photosensitive patients and highlighting the risks of even moderate UV exposure in this patient population.

Tunneling Nanotubes in Myeloid Cells: Perspectives for Health and Infectious Diseases.

Tunneling nanotubes (TNTs) are cellular connections, which represent a novel route for cell-to-cell communication. Strong evidence points to a role for TNTs in the intercellular transfer of signals, molecules, organelles, and pathogens, involving them in many cellular functions. In myeloid cells (e.g., monocytes/macrophages, dendritic cells, and osteoclasts), intercellular communication via TNT contributes to their differentiation and immune functions, by favoring material and pathogen transfer, as well as cell fusion. This chapter addresses the complexity of the definition and characterization of TNTs in myeloid cells, the different processes involved in their formation, their existence in vivo, and finally their function(s) in health and infectious diseases, with the example of HIV-1 infection.

Novel insights into the role of TREM2 in cerebrovascular diseases.

Cerebrovascular diseases (CVDs) include conditions such as stroke, cerebral amyloid angiopathy (CAA) and cerebral small vessel disease (CSVD), which contribute significantly to global morbidity and healthcare burden. The pathophysiology of CVD is complex, involving inflammatory, cellular and vascular mechanisms. Recently, research has focused on triggering receptor expressed on myeloid cells 2 (TREM2), an immune receptor predominantly found on microglia. TREM2 interacts with multiple signalling pathways, particularly toll-like receptor 4 (TLR4) and nuclear factor kappa B (NF-κB), inhibiting patients' inflammatory response. This receptor plays an essential role in both immune regulation and neuroprotection. TREM2 deficiency or dysfunction is associated with impaired microglial responses, exacerbated neurodegeneration and neuroinflammation. Up until recently, TREM2 related studies have focused on neurodegenerative diseases (NDs), however a shift in focus towards CVDs is beginning to take place. Advancements in CVD research have focused on developing therapeutic strategies targeting TREM2 to enhance recovery and reduce long-term deficits. These include the exploration of TREM2 agonists and combination therapies with other anti-inflammatory agents, which may synergistically reduce neuroinflammation and promote neuroprotection. The modulation of TREM2 activity holds potential for innovative treatment approaches aimed at improving patient outcomes following cerebrovascular insults. This review compiles current research on TREM2, emphasising its molecular mechanisms, therapeutic potential, and advancements in CNS disease research.

Loss of TREM2 diminishes CAA despite an overall increase of amyloid load in Tg-SwDI mice.

INTRODUCTION: The microglial receptor triggering receptor expressed on myeloid cells 2 (TREM2) is a major risk factor for Alzheimer's disease (AD). Experimentally, Trem2 deficiency affects parenchymal amyloid beta (Aß) deposition. However, the role of TREM2 in cerebrovascular amyloidosis, especially cerebral amyloid angiopathy (CAA), remains unexplored. METHODS: Tg-SwDI (SwDI) mice, a CAA-prone model of AD, and Trem2 knockout mice were crossed to generate SwDI/TWT, SwDI/THet, and SwDI/TKO mice, followed by pathological and biochemical analyses at 16 months of age. RESULTS: Loss of Trem2 led to a dramatic decrease in CAA and microglial association, despite a marked increase in overall brain Aß load. Single nucleus RNA sequencing analysis revealed that in the absence of Trem2, microglia were activated but trapped in transition to the fully reactive state, with distinct responses of vascular cells. DISCUSSION: Our study provides the first evidence that TREM2 differentially modulates parenchymal and vascular Aß pathologies, offering significant implications for both TREM2- and Aß-targeting therapies for AD. HIGHLIGHTS: Triggering receptor expressed on myeloid cells 2 (TREM2) differentially modulates brain parenchymal and vascular amyloidosis. Loss of Trem2 markedly reduces cerebral amyloid angiopathy despite an overall increase of amyloid beta load in Tg-SwDI mice. Microglia are trapped in transition to the fully reactive state without Trem2. Perivascular macrophages and other vascular cells have distinct responses to Trem2 deficiency. Balanced TREM2-targeting therapies may be required for optimal outcomes.

Familial cerebral amyloid disorders with prominent white matter involvement.

Familial cerebral amyloid disorders are characterized by the accumulation of fibrillar protein aggregates, which deposit in the parenchyma as plaques and in the vasculature as cerebral amyloid angiopathy (CAA). Amyloid ß (Aß) is the most common of these amyloid proteins, accumulating in familial and sporadic forms of Alzheimer's disease and CAA. However, there are also a number of rare, hereditary, non-Aß cerebral amyloidosis. The clinical manifestations of these familial cerebral amyloid disorders are diverse, including cognitive or neuropsychiatric presentations, intracerebral hemorrhage, seizures, myoclonus, headache, ataxia, and spasticity. Some mutations are associated with extensive white matter hyperintensities on imaging, which may or may not be accompanied by hemorrhagic imaging markers of CAA; others are associated with occipital calcification. We describe the clinical, imaging, and pathologic features of these disorders and discuss putative disease mechanisms. Familial disorders of cerebral amyloid accumulation offer unique insights into the contributions of vascular and parenchymal amyloid to pathogenesis and the pathways underlying white matter involvement in neurodegeneration. With Aß immunotherapies now entering the clinical realm, gaining a deeper understanding of these processes and the relationships between genotype and phenotype has never been more relevant.

Immunomodulatory Therapy for Ischemic Heart Disease.

Ischemic heart disease is a leading cause of death worldwide, manifested clinically as myocardial infarction (and ischemic cardiomyopathy. Presently, there exists a notable scarcity of efficient interventions to restore cardiac function after myocardial infarction. Cumulative evidence suggests that impaired tissue immunity within the ischemic microenvironment aggravates cardiac dysfunction, contributing to progressive heart failure. Recent research breakthroughs propose immunotherapy as a potential approach by leveraging immune and stroma cells to recalibrate the immune microenvironment, holding significant promise for the treatment of ischemic heart disease. In this Primer, we highlight three emerging strategies for immunomodulatory therapy in managing ischemic cardiomyopathy: targeting vascular endothelial cells to rewire tissue immunity, reprogramming myeloid cells to bolster their reparative function, and utilizing adoptive T cell therapy to ameliorate fibrosis. We anticipate that immunomodulatory therapy will offer exciting opportunities for ischemic heart disease treatment.

Soluble epoxide hydrolase inhibition impairs triggering receptor expressed on myeloid cells-1 in periodontal tissue.

AIMS: Periodontitis is a prevalent inflammatory disorder affecting the oral cavity, driven by dysbiotic oral biofilm and host immune response interactions. While the major clinical focus of periodontitis treatment is currently controlling oral biofilm, understanding the immune response is crucial to prevent disease progression. Soluble epoxide hydrolase (sEH) inhibition has shown promise in preventing alveolar bone resorption. Triggering receptors expressed on myeloid cells (TREMs) play pivotal roles in regulating inflammation and bone homeostasis, and dysregulation of TREM signaling is implicated in periodontitis. Here, we investigated the impact of sEH inhibition on TREM 1 and 2 expression, associated with inflammatory cytokines, and histologically assessed the inflammatory infiltrate in periodontal tissue. METHODS: The experimental periodontitis model was induced by placing a ligature around the upper second molar. For 14 days, animals were treated daily with a sEH inhibitor (TPPU) or vehicle. The alveolar bone loss was examined using a methylene blue stain. Gingival tissues were used to measure the mRNA expression of TREM-1, TREM-2, IKKß, NF-κB, IL-1ß, IL-6, IL-8, and TNF-α by RT-qPCR. Another set of experiments was performed to determine the histological inflammatory scores. RESULTS: In a ligature-induced periodontitis model, sEH inhibition prevented alveolar bone loss and reduced TREM1 expression, albeit with a slight elevation compared to the disease-free group. In contrast, TREM2 expression remained elevated, suggesting sustained immunomodulation favoring resolution. The inhibition of sEH reduced the expression of NF-κB, IL-1ß, and TNF-α, while no differences were found in the expression of IL-6, IL-8, and IKKß. In histological analysis, sEH inhibition reduced the inflammatory leukocyte infiltrate in periodontal tissues close to the ligature. CONCLUSION: These findings underscore the potential of sEH inhibition to modulate periodontal inflammation by regulating TREM-1 alongside decreased IL-1ß and TNF-α expression, highlighting a promising therapeutic approach for periodontitis management.

New insights into SYK targeting in solid tumors.

Spleen tyrosine kinase (SYK) is predominantly expressed in hematopoietic cells and has been extensively studied for its pivotal role in B cell malignancies and autoimmune diseases. In epithelial solid tumors, SYK shows a paradoxical role, acting as a tumor suppressor in some cancers while driving tumor growth in others. Recent preclinical studies have identified the role of SYK in the tumor microenvironment (TME), revealing that SYK signaling in immune cells, especially B cells, and myeloid cells, promote immunosuppression, tumor growth, and metastasis across various solid tumors. This review explores the emerging roles of SYK in solid tumors, the mechanisms of SYK activation, and findings from preclinical and clinical studies of SYK inhibitors as either standalone treatments or in combination with immunotherapy or chemotherapy for solid tumors.

TREM2, a critical activator of pyroptosis, mediates the anti­tumor effects of piceatannol in uveal melanoma cells via caspase 3/GSDME pathway

Uveal melanoma (UM) is the most prevalent type of primary intraocular malignancy and is prone to metastasize, particularly to the liver. However, due to the poor understanding of the pathogenesis of UM, effective therapeutic approaches are lacking. As a phenolic compound extracted from grapes, piceatannol (PIC) exhibits anti­cancer properties. To the best of our knowledge, however, the effects of PIC on UM have not been well investigated. Therefore, in the present study, considering the impact of pyroptosis on modulating cell viability, the mechanism underlying the effects of PIC on UM cell proliferation was explored. The inhibitory effect of PIC on proliferation of UM cells was detected by cell counting kit­8 assay. Wound healing was used to investigate the effects of PIC on the migration of UM cells. Activity detecting assays were performed to test the apoptosis and oxidant level in UM cells. Western blotting and RT­qPCR were used to detect the inflammatory and pyroptotic levels of UM cell after PIC treatment. PIC­treated UM cells were screened by high­throughput sequencing to detect the differential expression of RNA and differential genes. Si­TREM2 transfection was used to verify the important role of TREM2 in the effects of PIC. Immunohistochemical staining was used to observe the expressions of TREM2 and GSDMR of tumor in nude mice after PIC administration. PIC effectively inhibited proliferation ability of C918 and Mum­2b UM cell lines via enhancing apoptosis, as evidenced by enhanced activities of caspase 3 and caspase 9. In addition, treatment of UM cells with PIC attenuated cell migration in a dose­dependent manner. PIC increased reactive oxygen species levels and suppressed the activity of the antioxidant enzymes superoxide dismutase, glutathione­S­transferase, glutathione peroxidase and catalase. PIC inhibited inflammatory responses in C918 cells. PIC treatment upregulated IL­1ß, IL­18 and Nod­like receptor protein 3 and downregulated gasdermin D (GSDMD). RNA sequencing results revealed the activation of an unconventional pyroptosis­associated signaling pathway, namely caspase 3/GSDME signaling, following PIC treatment, which was mediated by triggering receptor expressed on myeloid cells 2 (TREM2) upregulation. As an agonist of TREM2, COG1410­mediated TREM2 upregulation inhibited proliferation of C918 cells, displaying similar effects to PIC. Furthermore, PIC inhibited tumor growth via regulating the TREM2/caspase 3/GSDME pathway in a mouse model. Collectively, the present study revealed a novel mechanism underlying the inhibitory effects of PIC on UM, providing a potential treatment approach for UM in clinic.

Crosstalk Between Cancer-associated Fibroblasts and Myeloid Cells Shapes the Heterogeneous Microenvironment of Gastric Cancer.

Background: Targeted therapies have improved the clinical outcomes of most patients with cancer. However, the heterogeneity of gastric cancer remains a major hurdle for precision treatment. Further investigations into tumor microenvironment heterogeneity are required to resolve these problems. Methods: In this study, bioinformatic analyses, including metabolism analysis, pathway enrichment, differentiation trajectory inference, regulatory network construction, and survival analysis, were applied to gain a comprehensive understanding of tumor microenvironment biology within gastric cancer using single-cell RNA-seq and public datasets and experiments were carried out to confirm the conclusions of these analyses. Results: We profiled heterogeneous single-cell atlases and identified eight cell populations with differential expression patterns. We identified two cancer-associated fibroblasts (CAFs) subtypes, with particular emphasis on the role of inflammatory cancer-associated fibroblasts (iCAFs) in EMT and lipid metabolic crosstalk within the tumor microenvironment. Notably, we detected two differentiation states of iCAFs that existed in different tissues with discrepant expression of genes involved in immuno-inflammation or ECM remodeling. Moreover, investigation of tumor-infiltrating myeloid cells has revealed the functional diversity of myeloid cell lineages in gastric cancer. Of which a proliferative cell lineage named C1QC+MKI67+TAMs was recognized with high immunosuppressive capacities, suggesting it has immune suppression and cell proliferation functions in the tumor niche. Finally, we explored regulatory networks based on ligand-receptor pairs and found crucial pro-tumor crosstalk between CAFs and myeloid cells in the tumor microenvironment (TME). Conclusion: These findings provide insights for future cancer treatments and drug discovery.