Search Results (81)

In individuals with diabetes, dysregulation of inflammatory processes hinders the progression of wounds into the proliferative phase, resulting in chronic, non-healing wounds. Total saponins from Rhizoma Panacis majoris (SRPM), bioactive compounds naturally extracted from the rhizome of Panax japonicus C.A.Mey. var. major (Burk.) C.Y.Wu and K.M.Feng, have demonstrated extensive anti-inflammatory and immunomodulatory properties. This study aims to elucidate the molecular mechanisms underlying the facilitative effects of SRPM on diabetic wound healing, with particular emphasis on its anti-inflammatory actions. A high-fat diet combined with streptozotocin (STZ) administration was used to induce type 2 diabetes in rats. After two weeks of oral treatment with SRPM suspension, a wound model was established. Subsequently, a two-week course of combined local and systemic therapy was administered using both SRPM suspension and SRPM gel. SRPM markedly reduces the levels of pro-inflammatory mediators, including IL-1α, IL-1β, IL-6, MIP-1α, TNF-α, and MCP-1, in both rat tissues and serum. Concurrently, it increases the expression of anti-inflammatory cytokines such as IL-10, TGF-β1, and PDGF-BB, while also enhancing the expression of the tissue remodelling marker bFGF. Additionally, SRPM significantly decreases the accumulation of apoptotic cells within tissues by downregulating the pro-apoptotic gene Caspase-3, upregulating the anti-apoptotic gene Bcl-2, and increasing the expression of the apoptotic cell clearance receptor MerTK. Moreover, SRPM inhibits neutrophil infiltration and the release of neutrophil extracellular traps (NETs) in tissues, promotes macrophage polarisation towards the M2 phenotype, and activates the Wnt/β-catenin signalling pathway at the molecular level. SRPM promotes the healing of wounds in diabetic rats potentially due to its anti-inflammatory properties. Full article

Efferocytosis, the process by which macrophages clear apoptotic cells, plays a vital role in maintaining immune homeostasis. This study explores the influence of inflammatory cytokines—tumor necrosis factor-alpha (TNF-α) and transforming growth factor-beta (TGF-β)—on efferocytosis dysregulation in coronary artery disease (CAD). Peripheral blood samples were collected from 27 non-obstructive and 29 obstructive CAD patients to isolate monocytes, which were then differentiated into M1 and M2 macrophages using specific cytokine stimuli. These macrophages were transfected with TNF-α and TGF-β siRNA to assess cytokine impact on efferocytosis. Expression levels of the efferocytosis receptor MERTK and its regulatory protease ADAM17 were quantified via qPCR. Statistical analysis revealed significantly higher MERTK expression in M2 macrophages compared to M1 (p = 0.002). Notably, TNF-α silencing enhanced efferocytosis in M2 macrophages, with increased clearance of early apoptotic bodies in non-obstructive CAD and late apoptotic bodies in obstructive CAD (both p < 0.001). These findings suggest that macrophage phenotype, apoptotic stage, and cytokine environment influence efferocytosis efficiency and may involve pathways beyond MERTK-ADAM17. They offer preliminary mechanistic insights into cytokine-mediated modulation of efferocytosis in CAD. Further in vivo studies are needed to confirm these observations and evaluate their relevance for future therapeutic strategies. Full article

Muscle gradually loses its regenerative capacity with aging. Recent evidence highlights age-related immune dysregulation as a key driver of satellite cell dysfunction and reduced muscle regeneration. Timely elimination of apoptotic cells by phagocytes through efferocytosis is essential for tissue repair. Therefore, exploring age-related alterations in the molecular machinery of efferocytosis and their impact on muscle regeneration is of great relevance. This study examined the efferocytic machinery in the gastrocnemius muscle tissue of young and aged rats after doxorubicin-induced acute myotoxicity and assessed the potential of Vitamin B12-loaded chitosan nanoparticles (B12 CS NPS) to enhance efferocytosis and promote skeletal muscle injury repair in aged rats. Aged rats exhibited impaired efferocytosis with a significant reduction in MerTK, PPARγ, and miR-124 expression, and increased ADAM17 expression. B12 CS NPS administration significantly improved efferocytosis and reduced necrotic tissue areas, accompanied by increased MerTK, PPARγ, and miR-124, and reduced ADAM17 expression. Supplementation with B12 CS NPS significantly enhanced satellite cell proliferation and differentiation, which was indicated by upregulated expression of Pax7, Myog, and MyoD. These findings reveal that age-related alterations in regulatory molecules impair efferocytosis in aged muscle and demonstrate the potential of B12 CS NPs to enhance efferocytosis and improve skeletal muscle repair. Full article

Inherited retinal degenerations (IRDs), driven by pathogenic mutations, often involve primary dysfunction of the retinal pigment epithelium (RPE)—a pathogenic feature shared with atrophic age-related macular degeneration (aAMD), despite aAMD’s multifactorial etiology. Prominin-1 (Prom1), traditionally linked to photoreceptor pathology, has an unclear role in RPE homeostasis. We assessed Prom1 expression in C57BL/6J mouse retina sections and RPE flat mounts using immunohistochemistry and generated Prom1-knockout (KO) mouse RPE cells via CRISPR/Cas9. Bulk RNA sequencing with DESeq2 and gene set enrichment analysis (GSEA) revealed Prom1-regulated pathways. Prom1-KO cells exhibited upregulation of Grem1, Slc7a11, Serpine2, Il1r1, and IL33 and downregulation of Ablim1, Cldn2, IGFBP-2, BMP3, and OGN. Hallmark pathway interrogation identified reduced expression of PINK1 (mitophagy) and MerTK (phagocytosis), implicating defects in mitochondrial quality control and outer segment clearance. Enrichment analysis revealed activation of E2F/MYC targets, mTORC1 signaling, oxidative phosphorylation, and TNFα/NF-κB signaling, alongside suppression of apical junctions, bile acid metabolism, and Epithelial-Mesenchymal Transition (EMT) pathways. These findings suggest Prom1 safeguards RPE integrity by modulating stress responses, mitochondrial turnover, phagocytosis, metabolism, and junctional stability. Our study uncovers Prom1-dependent signaling networks, providing mechanistic insights into RPE degeneration relevant to both IRD and aAMD, and highlights potential therapeutic targets for preserving retinal health. Full article

ZIKA virus (ZIKV) infections in human neonates and adults are associated with deleterious effects on brain cognition and neurological disorders. The mechanism(s) of ZIKV infection in neurons and associated neuronal antiviral responses are not fully understood. In this study, we determined the effects of ZIKV infectivity in human neuronal (SH-SY5Y) cells and mouse N2a cells/primary cultures of murine cortical neurons at early and late tested timepoints of infection. The human neuronal cells had higher ZIKV loads compared to the mouse N2a cells, but the viral loads in the murine cortical neurons were between the loads in these two in vitro cell lines. The murine cortical neurons were thought to be more permissive to ZIKV infection, but viral infection kinetics showed a declining trend like that observed in the mouse N2a cells. We noted that infectious extracellular vesicle (EV)-mediated ZIKV infection showed higher viral loads in the SH-SY5Y cells compared to direct infection with laboratory virus stocks. Similar results were obtained with ZIKV infectious EVs in the mouse N2a cells and cortical neurons. In addition, we noted that ZIKV infection significantly induced EV secretion from all three neuronal cells. Also, we found that ZIKV infection modulates the expression of type 1 interferons (IFNs) and entry receptors such as Tyro3, Axl, and MER-TK (TAM). Alongside the increased ZIKV loads in the SH-SY5Y cells, IFN-beta transcript levels and receptors Tyro3/MER-TK were upregulated at early timepoints of infection. Overall, the reduced ZIKV loads and decreasing IFN expression in the mouse neuronal cells suggested a unique murine cellular ability to restrict and limit viral replication. This could be one of the reasons for the unavailability of wild-type mouse models for ZIKV infection. Our data further shows that ZIKV may preferentially infect human rather than murine neuronal cells, and this could be the potential reason for microcephaly in newborns. Full article

Brain damage caused by hypoxia-ischemia is a serious complication for a newborn with possible life-long sequelae. To develop targeted neuroprotective strategies, it is essential to understand the mechanisms of injury, particularly the role of microglial phagocytosis, which may contribute to neuronal loss after hypoxia-ischemia. The aim was to evaluate neuronal cell death by phagocytosis in neonatal hypoxia-ischemia by investigating key signaling molecules and the effect of gene deletion of the phagocytic receptor Myeloid-epithelial-reproductive tyrosine kinase (MerTK) in a neonatal mouse model. MerTK, growth arrest–specific 6, and genes related to phagoptosis were regulated in the brain 6–72 h after hypoxic ischemia. Brain injury was reduced in MerTK knock-out vs. wild-type mice by 48% in gray matter (p = 0.002) and by 32% in white matter (p = 0.04). There was a near 40% reduction in NeuN immunoreactivity in microglia in MerTK knock-out mice vs. wild-type (p = 0.03) indicating attenuation of neuronal phagocytosis by microglia. In summary, the reduction in microglial neuronal engulfment and brain injury in MerTK-deficient mice strongly indicates that phagoptosis contributes to neuronal loss after neonatal hypoxia-ischemia. This insight suggests that targeting MerTK-mediated phagocytosis may represent a potential therapeutic approach in neonatal hypoxia-ischemic brain injury. Full article

Ras gene mutations are frequently observed in many types of cancers. However, there are currently no effective anticancer drugs against Ras-induced cancers. Therefore, identifying the downstream effectors of the Ras signaling pathway can facilitate the development of promising novel therapeutic approaches. We previously showed that oncogenic Ras induces the expression of the receptor tyrosine kinase c-Mer proto-oncogene tyrosine kinase (MerTK) in an interleukin-1 family member NF-HEV/IL-33-dependent manner and that IL-33 and MerTK contribute to oncogenic Ras-induced cell migration. In the present study, we purified the MerTK complex from NIH-3T3 cells transformed by the expression of oncogenic Ras, H-Ras (G12V). Mass spectrometric analysis identified STK38 (also known as NDR1) as a candidate binding partner for MerTK. STK38 is a serine/threonine protein kinase that plays diverse roles in normal and cancerous cells. In addition to MerTK knockdown, STK38 knockdown effectively attenuated the H-Ras (G12V)-induced migration of NIH-3T3 cells. STK38 kinase activity is required for oncogenic Ras-induced cell migration and MerTK tyrosine phosphorylation. Furthermore, MerTK or STK38 knockdown attenuated the activation of Rac1 and Cdc42. Taken together, these results revealed a novel role for STK38 in oncogenic Ras-induced enhanced cell migration, which may be useful for developing novel therapeutic strategies targeting Ras-mutated cells. Full article

Cationic polyamine-based carbon dots (CDs) are increasingly being explored for biomedical applications. These ultrasmall (<10 nm) fluorescent nanoparticles, synthesized from organic precursors and functionalized with polyamines, possess a strong positive surface charge that enables efficient complexation and delivery of nucleic acids, making them promising candidates for gene therapy. However, the mechanisms by which the immune system, particularly macrophages, recognizes and responds to these nanomaterials remain poorly understood. In this study, we investigated the role of surface receptors in the uptake and biological effects of cationic polyamine-based CDs in macrophages. Our data showed that Fc receptors and the Toll-like receptor 4 (TLR4) were minimally involved in CD internalization and associated cellular responses in contrast to scavenger receptors (SRs). Indeed, SR inhibition reduced CD-induced cell viability loss, LDH release, and secretion of the pro-inflammatory cytokine IL-1β. Among SRs, SR-A1 was identified as a key receptor mediating CD recognition and toxicity, likely through activation of the MERTK signaling pathway. Importantly, these mechanisms occurred in the absence of serum, indicating that protein corona formation is not required for CD interaction with macrophage surface receptors. Overall, our findings highlight the prominent role of SRs, particularly SR-A1, as receptors recognizing cationic polyamine-based CDs on the surface of macrophages, and provide new insights into the cellular mechanisms underlying the immunotoxicity of these carbon-based nanomaterials. Full article

Metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH) are spreading worldwide as the most critical causes of cirrhosis and hepatocellular carcinoma (HCC). Thus, improving the screening and managing strategies for patients with MASLD or MASH is necessary. A traditional non-systemic review provided this narrative. Genetic variations associated with the development of MASLD and MASH, such as PNPLA3, TM6SF2, GCKR, MBOAT7, MERTK, and HSD17B13, were initially reviewed. PNPLA3 genetic variants appeared to be strongly associated with the increased pathogenesis of MASLD, MASH, cirrhosis, and HCC. We also reviewed the useful polygenic risk score (PRS) for the development of MASLD, MASH, their related cirrhosis, and the occurrence of HCC. PRSs appeared to be better predictors of MASLD, MASH, the development of cirrhosis, and the occurrence of HCC in patients with MASLD or MASH than any single-nucleotide polymorphisms. RNA interference and antisense nucleotides against the genetic variations of PNPLA3 and HSD17B13 are also being developed. Multidisciplinary collaboration and cooperation involving hepatologists, geneticists, pharmacologists, and pathologists should resolve complicated problems in MASLD and MASH. This narrative review highlights the importance of the genetic susceptibility and PRS as predictive markers and personalized medicine for patients with MASLD or MASH in the future. Full article

Background: A hallmark of cancer is the presence of an immunosuppressive tumor microenvironment (TME). Immunosuppressive M2 macrophages (MΦs) in the TME facilitate escape from immune surveillance and promote tumor growth; therefore, TME-induced immunosuppression is a potent immunotherapeutic approach to treating cancer. Methods: Cancer cell-secreted proteins were detected by using liquid chromatography–mass spectrometry (LC-MS). Neutralizing antibodies (nAbs) were used to assess which proteins were involved in MΦs polarization and differentiation. The protein–protein interaction was characterized using co-immunoprecipitation and immunofluorescence assays. Cancer-secreted heat shock protein 70 (Hsp70) protein was quantified using an enzyme-linked immunosorbent assay (ELISA). MΦ polarization and tumor growth were assessed in vivo with subcutaneous LLC-GFP tumor models and toll-like receptor 2 (TLR2) knockout mice; in vitro assessments were conducted using TLR2 knockout and both LLC-GFP and LN227 lentiviral-mediated knockdown (KD) cells. Results: Cancer cells released a secreted form of Hsp70 that acted on MΦ TLR2 to upregulate Mer receptor tyrosine kinase (MerTK) and induce MΦ M2 polarization. Hsp70 nAbs led to a reduction in CD14 expression by 75% in THP-1 cells in response to Gli36 EMD-CM. In addition, neutralizing TLR2 nAbs resulted in a 30% and 50% reduction in CD14 expression on THP-1 cells in response to MiaPaCa-2 and Gli36 exosome/microparticle-depleted conditioned media (EMD-CMs), respectively. Hsp70, TLR2, and MerTK formed a protein complex. Tumor growth and intra-tumor M2 MΦs were significantly reduced upon cancer cell Hsp70 knockdown and in TLR2 knockout mice. Conclusions: Cancer-secreted Hsp70 interacts with TLR2, upregulates MerTK on MΦs, and induces immunosuppressive MΦ M2 polarization. This previously unreported action of secreted Hsp70 suggests that disrupting the Hsp70-TLR2-MerTK interaction could serve as a promising immunotherapeutic approach to mitigate TME immunosuppression in solid cancers. Full article

Zika virus (ZIKV), a member of the Flaviviridae family, is primarily transmitted through mosquito bites, but can also spread via sexual contact and from mother to fetus. While often asymptomatic, ZIKV can lead to severe neurological conditions, including microcephaly in fetuses and Guillain–Barré Syndrome in adults. ZIKV can infect placental macrophages and fetal microglia in vivo as well as human monocytes and monocyte-derived macrophages (MDMs) in vitro. Here, we observed that both human monocytes, and MDM particularly, supported ZIKV replication without evident cytopathicity, with virions accumulating in cytoplasmic vacuoles. We also investigated whether the cytokine-induced polarization of MDMs into M1 or M2 cells affected ZIKV replication. The stimulation of MDMs with pro-inflammatory cytokines (interferon-γ and tumor necrosis factor-α) polarized MDMs into M1 cells, significantly reducing ZIKV replication, akin to previous observations with a human immunodeficiency virus type-1 infection. In contrast, M2 polarization, induced by interleukin-4, did not affect ZIKV replication in MDMs. M1 polarization selectively reduced the expression of MERTK, a TAM family putative entry receptor, and increased the expression of several interferon-stimulated genes (ISGs) previously associated with the containment of ZIKV infection; of interest, ZIKV infection transiently boosted the expression of some ISGs in M1-MDMs. These findings suggest a dual mechanism of ZIKV restriction in M1-MDMs and highlight potential antiviral strategies targeting innate immune responses. Full article

Head and neck squamous cell carcinoma (HNSCC) is diagnosed in more than 71,000 patients each year in the United States, with nearly 16,000 associated deaths. One significant hurdle in the treatment of HNSCC is acquired and intrinsic resistance to existing therapeutic agents. Over the past several decades, the University of Wisconsin has formed a multidisciplinary team to move basic scientific discovery along the translational spectrum to impact the lives of HNSCC patients. In this review, we outline key discoveries made throughout the years at the University of Wisconsin to deepen our understanding of therapeutic resistance in HNSCC and how a strong, interdisciplinary team can make significant advances toward improving the lives of these patients by combatting resistance to established therapeutic modalities. We are profoundly grateful to the many scientific teams worldwide whose groundbreaking discoveries, alongside evolving clinical paradigms in head and neck oncology, have been instrumental in making our work possible. Full article

Patients with unstable angina present clinical characteristics of atherosclerotic plaque vulnerability, contrary to chronic coronary syndrome patients. The process of athersclerotic plaque destabilization is also regulated by microRNA particles. In this study, the investigation on expression levels of microRNAs inhibiting the expression of proteins that protect from atherosclerotic plaque progression (miR-92a inhibiting KLF2, miR-10b inhibiting KLF4, miR-126 inhibiting MerTK, miR-98 inhibiting IL-10, miR-29b inhibiting TGFβ1) was undertaken. A number of 62 individuals were enrolled—unstable angina (UA, n = 14), chronic coronary syndrome (CCS, n = 38), and healthy volunteers (HV, n = 10). Plasma samples were taken, and microRNAs expression levels were assessed by qRT-PCR. As a result, the UA patients presented significantly increased miR-10b levels compared to CCS patients (0.097 vs. 0.058, p = 0.033). Moreover, in additional analysis when UA patients were grouped together with stable patients with significant plaque in left main or proximal left anterior descending (“UA and LM/proxLAD” group, n = 29 patients) and compared to CCS patients with atherosclerotic lesions in other regions of coronary circulation (“CCS other” group, n = 25 patients) the expression levels of both miR-10b (0.104 vs. 0.046; p = 0.0032) and miR-92a (92.64 vs. 54.74; p = 0.0129) were significantly elevated. In conclusion, the study revealed significantly increased expression levels of miR-10b and miR-92a, a regulator of endothelial protective KLF factors (KLF4 and KLF2, respectively) in patients with more vulnerable plaque phenotypes. Full article

Outcomes are poor in patients with advanced or relapsed Ewing sarcoma (EWS) and current treatments have significant short- and long-term side effects. New, less toxic and more effective treatments are urgently needed. MER proto-oncogene tyrosine kinase (MERTK) promotes tumor cell survival, metastasis, and resistance to cytotoxic and targeted therapies in a variety of cancers. MERTK was ubiquitously expressed in five EWS cell lines and five patient samples. Moreover, data from CRISPR-based library screens indicated that EWS cell lines are particularly dependent on MERTK. Treatment with MRX-2843, a first-in-class, MERTK-selective tyrosine kinase inhibitor currently in clinical trials, decreased the phosphorylation of MERTK and downstream signaling in a dose-dependent manner in A673 and TC106 cells and provided potent anti-tumor activity against all five EWS cell lines, with IC₅₀ values ranging from 178 to 297 nM. Inhibition of MERTK correlated with anti-tumor activity, suggesting MERTK inhibition as a therapeutic mechanism of MRX-2843. Combined treatment with MRX-2843 and BCL-2 inhibitors venetoclax or navitoclax provided enhanced therapeutic activity compared to single agents. These data highlight MERTK as a promising therapeutic target in EWS and provide rationale for the development of MRX-2843 for the treatment of EWS, especially in combination with BCL-2 inhibitors. Full article

HER2-Low is defined as low levels of HER2 expression, based on a score of 1+ on immunohistochemical (IHC) assay or as an IHC score of 2+ and negative results on in situ hybridization (ISH or FISH). They are a heterogeneous population of breast cancers that vary in prognosis and sensitivity to systemic treatments. The frequency and clinical characteristics of pathogenic germline variants (PGVs) in HER2-Low breast cancer (BC) patients is not defined. We analyzed results from patients with BC who underwent multi-gene panel testing (MGPT) (maximum 145 genes) between 2018–2019. We reclassified HER-2 status accordingly. Relationships between the variables of interest were assessed by adopting the proportional regression Cox models. Of a total of 167 BC patients who underwent MGPT, half were hormone-receptor-positive. The median age was 45 years. About two thirds of the patients were in the earlier stage of BC. A total of 57% of the cases were reclassified as HER-2-negative or -Low. PGVs were found in 19% of the patients overall, as follows: seven BRCA1, four BRCA2, two ATM, one ATR, two CFTR, three CHEK2, one FANCA, one MERTK, one MLH1, three MUTYH, one RAD50, three RAD51C, one RECQL4, and two TP53 mutations. In HER2-Low, 26.5% of the patients had PGVs, and in the overall cohort, this was 19.8%. In conclusion, differences in the prevalence of deleterious germline mutations in HER2-Low BC patients compared to non-HER2-Low BC patients were identified. Similar alterations in BRCA were observed in this group of patients compared to the overall cohort. Germline genetic tests should be evaluated in larger cohorts of patients with HER2-Low status to better address the findings. Full article