Search Results (16)

Background: Diet-induced obesity (DIO) is increasingly linked to microglial proliferation in the central nervous system, yet the causal role of microglia in metabolic and behavioral changes remains unclear. Methods: Here, we investigated the effects of microglial suppression using the CSF-1R antagonist PLX 3397 (Pexidartinib; PLX) on body weight, adiposity, and sucrose preference in lean and DIO male and female rats. Microglial activation was quantified in the hypothalamus and nucleus tractus solitarius (NTS). Results: PLX administered during initial high-energy-diet (HED) exposure produced sex-specific effects: body weight increased in males but decreased in females. In male DIO rats, PLX+HED reduced body fat percentage without altering total weight. PLX treatment did not significantly alter body weight, food intake, or glucose tolerance in females. Hypothalamic microglial suppression was more extensive in males, whereas NTS suppression was similar across sexes. PLX also reversed HED-induced reductions in low-concentration sucrose preference in males. Substantial individual variability was observed in both susceptibility to DIO and responsiveness to PLX. Conclusions: These findings reveal a clear sexual dimorphism in microglial responses to HED, with females showing relative protection and males’ greater vulnerability. Overall, the results underscore the importance of accounting for sex differences in the design and application of microglia-targeted interventions. Full article

Background: Pigmented villonodular synovitis (PVNS), also known as tenosynovial giant cell tumor, is a rare proliferative disorder of the synovial membrane that primarily affects the knee joint. Despite advances in imaging and surgical techniques, diagnosis is often delayed, and optimal treatment remains debated. Methods: A Narrative review was conducted according to PRISMA guidelines using PubMed, MEDLINE, and Scopus databases from January 2000 to December 2024. Studies reporting on epidemiology, clinical features, imaging, treatment, and outcomes of PVNS were included. Results: Sixty-six studies encompassing 120 patients were included. The majority of cases were diffuse PVNS. MRI was the most effective imaging tool. Arthroscopic synovectomy was the most common treatment, though recurrence rates remained high, particularly in diffuse forms. Adjuvant treatments, including radiosynoviorthesis and biologic therapies such as infliximab or pexidartinib, were employed in recurrent or unresectable cases. Conclusions: Early diagnosis and complete surgical excision remain the mainstay of treatment. Combined open and arthroscopic approaches are recommended in diffuse PVNS. Further prospective studies are needed to define optimal long-term management. Full article

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease with limited therapeutic options and increasing global incidence, with a median survival of only 2–5 years. The clinical utility of macrophage polarization to regulate the progression of pulmonary fibrosis remains understudied. This study determined the efficacy of nintedanib and pexidartinib (PLX3397) combination therapy for treating IPF. Combination treatment effectively inhibited the progression of radiation-induced pulmonary fibrosis (RIPF) and prolonged survival in bleomycin-treated mice. Micro-CT analysis revealed a significant tissue repair efficacy. The therapy significantly normalized the abnormal vascular structure observed during RIPF and bleomycin-induced pulmonary fibrosis progression and was accompanied by a decrease in the M2 population. Polarized M1 macrophages enhanced normalized tube formation of irradiated endothelial cells (ECs) in vitro; M2 macrophages increased adhesion in irradiated ECs and abnormal tube formation. Single-cell RNA sequencing data from patients with IPF further supports colony stimulating factor (CSF) 1 upregulation in macrophages and downregulation of capillary EC markers. This study highlights a promising combination strategy to overcome the therapeutic limitations of monotherapy with nintedanib for the treatment of IPF. Full article

Background/Objectives: Colony stimulating factor 1 receptor kinase (CSF1R) is a well-validated molecular target in drug discovery for various reasons. Based on the structure of an early lead molecule identified in our lab and the marketed drug Pexidartinib (PLX3397), we merged fragments of Pexidartinib with our pyrrolo[2,3-d]pyrimidine nucleus, and the idea was supported by initial molecular docking studies. Thus, several new compounds were synthesized with Pexidartinib fragments on C4, C5, and C6 on the pyrrolopyrimidine scaffold using molecular hybridization. Methods: Nine final products were synthesized using a combination of Buchwald-Hartwig and Suzuki-Miyaura cross-coupling reactions in three to four steps and in good yields. The analogues were subsequently profiled as CSF1R inhibitors in enzymatic and cellular assays, and ADME properties were evaluated for some derivatives. Results: N-Methyl-N-(3-methylbenzyl)-6-(6-((pyridin-3-ylmethyl)amino)pyridin-3-yl)-7H-pyrrolo[2,3-d]pyrimidin-4-amine (12b) emerged as the most potent CSF1R inhibitor, showing low-nanomolar enzymatic activity, cellular efficacy, and favorable ADME properties, highlighting its promise as a lead compound for further development. Conclusions: These findings suggest that combining structural elements from previously reported CSF1R inhibitors such as Pexidartinib could guide the development of improved drug candidates targeting this kinase. Full article

Acute myeloid leukemia (AML) is a heterogenous malignant hemopathy, and although new drugs have emerged recently, current treatment options still show limited efficacy. Therapy resistance remains a major concern due to its contribution to treatment failure, disease relapse, and increased mortality among patients. The underlying mechanisms of resistance to therapy are not fully understood, and it is crucial to address this challenge to improve therapy. Macrophages are immune cells found within the bone marrow microenvironment (BMME), of critical importance for leukemia development and progression. One defining feature of macrophages is their plasticity, which allows them to adapt to the variations in the microenvironment. While this adaptability is advantageous during wound healing, it can also be exploited in cancer scenarios. Thus, clinical and preclinical investigations that target macrophages as a therapeutic strategy appear promising. Existing research indicates that targeting macrophages could enhance the effectiveness of current AML treatments. This review addresses the importance of macrophages as therapeutic targets including relevant drugs investigated in clinical trials such as pexidartinib, magrolimab or bexmarilimab, but also provides new insights into lesser-known therapies, like macrophage receptor with a collagenous structure (MACRO) inhibitors and Toll-like receptor (TLR) agonists. Full article

Tumor-associated macrophages (TAMs) and cancer-associated fibroblasts (CAFs) are known to play supportive roles in tumor development and progression, but their interactions in colorectal cancer (CRC) remain unclear. Here, we investigated the effects of colon-cancer-derived CAFs on TAM differentiation, migration, and tumor immunity, both in vitro and in vivo. When co-cultured with monocytes, CAFs attracted monocytes and induced their differentiation into M2 macrophages. Immunohistology of surgically resected human CRC specimens and orthotopically transplanted mouse tumors revealed a correlation between numbers of CAFs and numbers of M2 macrophages. In a mouse model of CRC orthotopic transplantation, treatment with an inhibitor of the colony-stimulating factor-1 receptor (PLX3397) depleted M2 macrophages and increased CD8-positive T cells infiltrating the tumor nest. While this treatment had a minor effect on tumor growth, combining PLX3397 with anti-PD-1 antibody significantly reduced tumor growth. RNA-seq following combination therapy showed activation of tumor immunity. In summary, CAFs are involved in the induction and mobilization of M2 macrophage differentiation in the CRC tumor immune microenvironment, and the combination of cancer immunotherapy and PLX3397 may represent a novel therapeutic option for CRC. Full article

Hypoxic–ischemic brain injury induces metabolic dysfunction that ultimately leads to neuronal cell death. Astrocytes, a type of glial cell, play a key role in brain metabolism; however, their response to hypoxic–ischemic brain injury is not fully understood. Microglia were removed from murine primary mixed glial cultures to enrich astrocytes. Next, we explored genes whose expression is altered following oxygen–glucose deprivation using a microarray. Microarray analysis revealed that the expression of Nr4a1 and Nr4a3 is markedly increased in astrocyte-enriched cultures after 15 h of oxygen–glucose deprivation. The expression of both Nr4a1 and Nr4a3 was regulated by HIF-1α. At the protein level, NR4A1 was translocated from the nucleus to the cytoplasm following oxygen–glucose deprivation and co-localized with mitochondria in apoptotic cells; however, its localization was restored to the nucleus after reoxygenation. Oxygen–glucose deprivation causes an increase in NR4A1 mRNA in astrocytes as well as its nuclear to cytoplasmic transfer. Furthermore, reoxygenation enhances NR4A1 transcription and promotes its nuclear translocation. Full article

Tenosynovial giant cell tumor (TGCT) is a rare and locally aggressive benign tumor arising from the synovium of joints, bursae, and tendon sheaths. It is classified into localized (L-TGCT) and diffuse (D-TGCT) forms based on the extent of involvement. Surgical resection is the primary treatment, though achieving a definitive cure remains challenging due to the high recurrence rates, especially in D-TGCT. Systemic therapies targeting the CSF1-CSF1R axis have emerged as promising treatment options. CSF1R tyrosine kinase inhibitors (TKIs) such as imatinib, nilotinib, pexidartinib, and vimseltinib, alongside anti-CSF1R antibodies like emactuzumab, cabiralizumab, and lacnotuzumab, have shown encouraging results in managing TGCT, particularly when surgery is not feasible or poses significant morbidity. Other potential therapies, including local treatments and anti-inflammatory drugs, are being explored for TGCT management. This review provides an overview of systemic treatment options for D-TGCT, highlighting emerging therapeutic modalities and their potential implications. Effective management is crucial due to TGCT’s significant morbidity despite its non-life-threatening nature, necessitating novel approaches to improve patient prognosis and quality of life. Full article

The dihydrochloride salt of pexidartinib was synthesized and the crystal structure of its dihydrate was determined from single crystal data. The asymmetric unit consists of one formula unit. In the pexidartinib molecule, the N atom of the central pyridine ring and the pyridine-N atom of the pyrrolopyridine group are both protonated. The pexidartinib molecule forms N–H···O and N–H···Cl interactions with neighboring water molecules and chloride ions, respectively. Water/chloride (O–H···Cl) and water/water (O–H···O) interactions are also observed. Collectively, these intermolecular interactions result in a complex H-bonded framework structure. Full article

Small molecule protein kinase inhibitors (PKIs) have become an effective strategy for cancer patients. However, hepatotoxicity is a major safety concern of these drugs, since the majority are reported to increase transaminases, and few of them (Idelalisib, Lapatinib, Pazopanib, Pexidartinib, Ponatinib, Regorafenib, Sunitinib) have a boxed label warning. The exact rate of PKI-induced hepatoxicity is not well defined due to the fact that the majority of data arise from pre-registration or registration trials on fairly selected patients, and the post-marketing data are often based only on the most severe described cases, whereas most real practice studies do not include drug-related hepatotoxicity as an end point. Although these side effects are usually reversible by dose adjustment or therapy suspension, or by switching to an alternative PKI, and fatality is uncommon, all patients undergoing PKIs should be carefully pre-evaluated and monitored. The management of this complication requires an individually tailored reappraisal of the risk/benefit ratio, especially in patients who are responding to therapy. This review reports the currently available data on the risk and management of hepatotoxicity of all the approved PKIs. Full article

Glioblastoma multiforme (GBM) is the most aggressive form of adult brain tumor which is highly resistant to conventional treatment and therapy. Glioma cells are highly motile resulting in infiltrative tumors with poorly defined borders. Another hallmark of GBM is a high degree of tumor macrophage/microglia infiltration. The level of these tumor-associated macrophages/microglia (TAMs) correlates with higher malignancy and poorer prognosis. We previously demonstrated that inhibition of TAM infiltration into glioma tumors with the CSF-1R antagonist pexidartinib (PLX3397) can inhibit glioma cell invasion in-vitro and in-vivo. In this study, we demonstrate an important role for the chemokine receptor CCR1 in mediating microglia/TAM stimulated glioma invasion. Using two structurally distinct CCR1 antagonists, including a novel inhibitor “MG-1-5”, we were able to block microglial activated GL261 glioma cell invasion in a dose dependent manner. Interestingly, treatment of a murine microglia cell line with glioma conditioned media resulted in a strong induction of CCR1 gene and protein expression. This induction was attenuated by inhibition of CSF-1R. In addition, glioma conditioned media treatment of microglia resulted in a rapid upregulation of gene expression of several CCR1 ligands including CCL3, CCL5, CCL6 and CCL9. These data support the existence of tumor stimulated autocrine loop within TAMs which ultimately mediates tumor cell invasion. Full article

Background Anaplastic thyroid cancer (ATC) is the greatest lethal thyroid neoplasm with a low incidence and lacks an effective treatment strategy and standardized treatment protocol. PLX3397 (Pexidartinib) is an FDA-approved multitarget tyrosine kinase inhibitor. The research is designed to explore the possible anti-proliferative activity of pexidartinib on ATC, as well as its related molecular mechanisms. Methods The cell viability was assessed by CCK-8, LDH release, colony formation, and EdU detection assays. Apoptosis and the alteration on cell cycle arrest were characterized by flow cytometry (FCM). ER stress was evaluated by immunofluorescence (IF). ROS levels were determined by flow cytometry. Western blot assays were conducted to evaluate changes in key molecules related to apoptosis and ER stress. The ATC xenografts model was established, and immunohistochemistry was performed to validate the anti-ATC effects of pexidartinib in vivo. Results Pexidartinib significantly inhibited ATC cell proliferation and induced apoptosis and cell cycle arrest. Moreover, pexidartinib potently induced ER stress and elevated ROS in ATC cells, and the apoptotic cells and ER stress in ATC after administration of pexidartinib could be reversed by an ER stress inhibitor and ROS scavenger, respectively. Furthermore, pexidartinib treatment induced Nrf2 accumulation in nuclei and reduced the interaction of Nrf2 with Keap-1, and knockdown of Nrf2 enhanced the anti-ATC effects of pexidartinib in vitro. In addition, pexidartinib significantly inhibited ATC xenograft growth and proliferation in vivo, and the combination of ML385, an Nrf2 inhibitor, potently enhanced the anti-ATC effects of pexidartinib in vivo. Conclusion Our findings suggest pexidartinib is a potential agent for treating ATC. Co-administration with an Nrf2 inhibitor is an effective synergistic strategy. Full article

Breast cancer cell proliferation and migration are inhibited by naturally extracted trans-(−)-kusunokinin. However, three additional enantiomers of kusunokinin have yet to be investigated: trans-(+)-kusunokinin, cis-(−)-isomer and cis-(+)-isomer. According to the results of molecular docking studies of kusunokinin isomers on 60 breast cancer-related proteins, trans-(−)-kusunokinin was the most preferable and active component of the trans-racemic mixture. Trans-(−)-kusunokinin targeted proteins involved in cell growth and proliferation, whereas the cis-(+)-isomer targeted proteins involved in metastasis. Trans-(−)-kusunokinin targeted CSF1R specifically, whereas trans-(+)-kusunokinin and both cis-isomers may have bound AKR1B1. Interestingly, the compound’s stereoisomeric effect may influence protein selectivity. CSF1R preferred trans-(−)-kusunokinin over trans-(+)-kusunokinin because the binding pocket required a ligand planar arrangement to form a π-π interaction with a selective Trp550. Because of its large binding pocket, EGFR exhibited no stereoselectivity. MD simulation revealed that trans-(−)-kusunokinin, trans-(+)-kusunokinin and pexidartinib bound CSF1R differently. Pexidartinib had the highest binding affinity, followed by trans-(−)-kusunokinin and trans-(+)-kusunokinin, respectively. The trans-(−)-kusunokinin-CSF1R complex was found to be stable, whereas trans-(+)-kusunokinin was not. Trans-(±)-kusunokinin, a potential racemic compound, could be developed as a selective CSF1R inhibitor when combined. Full article

Pexidartinib is the first drug approved by the U.S. Food and Drug Administration specifically to treat the rare joint tumor tenosynovial giant cell tumor. In the current study, a validated, selective, and sensitive UPLC-MS/MS assay was developed for the quantitative determination of pexidartinib in plasma samples using gifitinib as an internal standard (IS). Pexidartinib and IS were extracted by liquid-liquid extraction using methyl tert-butyl ether and separated on an acquity BEH C₁₈ column kept at 40 °C using a mobile phase of 0.1% formic acid in acetonitrile: 0.1% formic acid in de-ionized water (70:30). The flow rate was 0.25 mL/min. Multiple reaction monitoring (MRM) was operated in electrospray (ESI)-positive mode at the ion transition of 418.06 > 165.0 for the analyte and 447.09 > 128.0 for the IS. FDA guidance for bioanalytical method validation was followed in method validation. The linearity of the established UPLC-MS/MS assay ranged from 0.5 to 1000 ng/mL with r > 0.999 with a limit of quantitation of 0.5 ng/mL. Moreover, the metabolic stability of pexidartinib in liver microsomes was estimated. Full article

The extracellular matrix (ECM) plays a key role in synaptogenesis and the regulation of synaptic functions in the central nervous system. Recent studies revealed that in addition to dopaminergic and serotoninergic neuromodulatory systems, microglia also contribute to the regulation of ECM remodeling. In the present work, we investigated the physiological role of microglia in the remodeling of perineuronal nets (PNNs), predominantly associated with parvalbumin-immunopositive (PV+) interneurons, and the perisynaptic ECM around pyramidal neurons in the hippocampus. Adult mice were treated with PLX3397 (pexidartinib), as the inhibitor of colony-stimulating factor 1 receptor (CSF1-R), to deplete microglia. Then, confocal analysis of the ECM and synapses was performed. Although the elimination of microglia did not alter the overall number or intensity of PNNs in the CA1 region of the hippocampus, it decreased the size of PNN holes and elevated the expression of the surrounding ECM. In the neuropil area in the CA1 str. radiatum, the depletion of microglia increased the expression of perisynaptic ECM proteoglycan brevican, which was accompanied by the elevated expression of presynaptic marker vGluT1 and the increased density of dendritic spines. Thus, microglia regulate the homeostasis of pre- and postsynaptic excitatory terminals and the surrounding perisynaptic ECM as well as the fine structure of PNNs enveloping perisomatic—predominantly GABAergic—synapses. Full article