Efficacy of durvalumab plus chemotherapy in advanced biliary duct cancer and biomarkers exploration.

BACKGROUND: The anti-PD-L1 antibody durvalumab has been approved for use in first-line advanced biliary duct cancer (ABC). So far, predictive biomarkers of efficacy are lacking. METHODS: ABC patients who underwent gemcitabine-based chemotherapy with or without durvalumab were retrospectively enrolled, and their baseline clinical pathological indices were retrieved from medical records. Overall (OS) and progression free survival (PFS) were calculated and analyzed. The levels of peripheral biomarkers from 48 patients were detected with assay kits including enzyme-linked immunosorbent assay. Genomic alterations in 27 patients whose tumor tissues were available were depicted via targeted next-generation sequencing. RESULTS: A total of 186 ABC patients met the inclusion criteria between January 2020 and December 2022 were finally enrolled in this study. Of these, 93 patients received chemotherapy with durvalumab and the rest received chemotherapy alone. Durvalumab plus chemotherapy demonstrated significant improvements in PFS (6.77 vs. 4.99 months; hazard ratio 0.65 [95% CI 0.48-0.88]; P = 0.005), but not OS (14.29 vs. 13.24 months; hazard ratio 0.91 [95% CI 0.62-1.32]; P = 0.608) vs. chemotherapy alone in previously untreated ABC patients. The objective response rate (ORR) in patients receiving chemotherapy with and without durvalumab was 19.1% and 7.8%, respectively. Pretreatment sPD-L1, CSF1R and OPG were identified as significant prognosis predictors in patients receiving durvalumab. ADGRB3 and RNF43 mutations were enriched in patients who responded to chemotherapy plus durvalumab and correlated with superior survival. CONCLUSION: This retrospective real-world study confirmed the clinical benefit of durvalumab plus chemotherapy in treatment-naïve ABC patients. Peripheral sPD-L1 and CSF1R are promising prognostic biomarkers for this therapeutic strategy. Presence of ADGRB3 or RNF43 mutations could improve the stratification of immunotherapy outcomes, but further studies are warranted to explore the underlying mechanisms.

Colony stimulating factor 1 receptor (Csf1r) expressing cell ablation in mafia (macrophage-specific Fas-induced apoptosis) mice alters monocyte landscape and atherosclerotic lesion characteristics.

Macrophage infiltration and accumulation in the atherosclerotic lesion are associated with plaque progression and instability. Depletion of macrophages from the lesion might provide valuable insights into plaque stabilization processes. Therefore, we assessed the effects of systemic and local macrophage depletion on atherogenesis. To deplete monocytes/macrophages we used atherosclerosis-susceptible Apoe- /- mice, bearing a MaFIA (macrophage-Fas-induced-apoptosis) suicide construct under control of the Csf1r (CD115) promotor, where selective apoptosis of Csf1r-expressing cells was induced in a controlled manner, by administration of a drug, AP20187. Systemic induction of apoptosis resulted in a decrease in lesion macrophages and smooth-muscle cells. Plaque size and necrotic core size remained unaffected. Two weeks after the systemic depletion of macrophages, we observed a replenishment of the myeloid compartment. Myelopoiesis was modulated resulting in an expansion of CSF1Rlo myeloid cells in the circulation and a shift from Ly6chi monocytes toward Ly6cint and Ly6clo populations in the spleen. Local apoptosis induction led to a decrease in plaque burden and macrophage content with marginal effects on the circulating myeloid cells. Local, but not systemic depletion of Csf1r+ myeloid cells resulted in decreased plaque burden. Systemic depletion led to CSF1Rlo-monocyte expansion in blood, possibly explaining the lack of effects on plaque development.

Unveiling the contribution of tumor-associated macrophages in driving epithelial-mesenchymal transition: a review of mechanisms and therapeutic Strategies.

Tumor-associated macrophages (TAMs), fundamental constituents of the tumor microenvironment (TME), significantly influence cancer development, primarily by promoting epithelial-mesenchymal transition (EMT). EMT endows cancer cells with increased motility, invasiveness, and resistance to therapies, marking a pivotal juncture in cancer progression. The review begins with a detailed exposition on the origins of TAMs and their functional heterogeneity, providing a foundational understanding of TAM characteristics. Next, it delves into the specific molecular mechanisms through which TAMs induce EMT, including cytokines, chemokines and stromal cross-talking. Following this, the review explores TAM-induced EMT features in select cancer types with notable EMT characteristics, highlighting recent insights and the impact of TAMs on cancer progression. Finally, the review concludes with a discussion of potential therapeutic targets and strategies aimed at mitigating TAM infiltration and disrupting the EMT signaling network, thereby underscoring the potential of emerging treatments to combat TAM-mediated EMT in cancer. This comprehensive analysis reaffirms the necessity for continued exploration into TAMs' regulatory roles within cancer biology to refine therapeutic approaches and improve patient outcomes.

MANEUVER: A Phase III study of pimicotinib to assess efficacy and safety in tenosynovial giant cell tumor patients.

Tenosynovial giant cell tumor (TGCT) is a rare, locally invasive soft tissue tumor arising from the synovium of joints, bursa and tendon sheaths and is associated with the overexpression of the colony-stimulating factor 1 (CSF-1) gene. Pimicotinib is an orally available, highly selective and potent small molecule CSF-1 receptor (CSF-1R) inhibitor with robust efficacy and safety profile in patients with TGCT and is under development in multiple diseases. In an open-label Phase I study in patients with TGCT not amenable to surgery, pimicotinib showed superior efficacy and safety. In this article, we elucidate the rationale and study design of the multi-region Phase III MANEUVER trial (NCT05804045), which is designed to assess the efficacy and safety of pimicotinib in patients with TGCT not amenable to surgical resection in Asia, North America and Europe.

Tenosynovial giant cell tumor (TGCT) is a rare soft tissue tumor which grows in the soft tissues around joints or parts of the body used for movement. It is caused by high levels of a type of protein called CSF-1. Even though surgery is a preferred treatment option, some patients may be unable to have surgery because of where the tumor is, how complicated it is, or the risk of serious problems or illness after the surgery. Therefore, new treatments that are safe, effective and that help people live well are still needed for this disease. Pimicotinib is a medicine which blocks CSF-1, and researches have shown that it is safe and effective for treating TGCT in smaller, early study. To confirm these results, researchers have started a larger study, known as MANEUVER, in some parts of Asia, North America and Europe. This study will confirm if pimicotinib is safe and effective in patients with TGCT who may not be able to have surgery.Clinical Trial Registration: NCT05804045 (ClinicalTrials.gov).

Heterozygous missense CSF1R variants hamper in vitro CD34+-derived dendritic cell generation but not in vivo dendritic cell development.

Colony stimulating factor 1 receptor (CSF1R) is an essential receptor for both colony stimulating factor 1 (CSF1) and interleukin (IL) 34 signaling expressed on monocyte precursors and myeloid cells, including monocytes, dendritic cells (DC), and microglia. In humans, dominant heterozygous pathogenic variants in CSF1R cause a neurological condition known as CSF1R-related disorder (CSF1R-RD), typically with late onset, previously referred to as adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP). CSF1R-RD is characterized by microglia reduction and altered monocyte function; however, the impact of pathogenic CSF1R variants on the human DC lineage remains largely unknown. We previously reported that cord blood CD34+ stem cell-derived DCs generated in vitro originate specifically from CSF1R expressing precursors. In this study, we examined the DC lineage of four unrelated patients with late-onset CSF1R-RD who carried heterozygous missense CSF1R variants (c.2330G>A, c.2375C>A, c.2329C>T, and c.2381T>C) affecting different amino acids in the protein tyrosine kinase domain of CSF1R. CD34+ stem cells and CD14+ monocytes were isolated from peripheral blood and subjected to an in vitro culture protocol to differentiate towards conventional DCs and monocyte-derived DCs, respectively. Flow cytometric analysis revealed that monocytes from patients with late-onset CSF1R-RD were still able to differentiate into monocyte-derived DCs in vitro, whereas the ability of CD34+ stem cells to differentiate into conventional DCs was impaired. Strikingly, the peripheral blood of patients contained all naturally occurring DC subsets. We conclude that the in vitro abrogation of DC-development in patients with heterozygous pathogenic missense CSF1R variants does not translate to an impairment in DC development in vivo and speculate that CSF1R signalling in vivo is compensated, which needs further study.

JDF promotes the apoptosis of M2 macrophages and reduces epithelial-mesenchymal transition and migration of liver cancer cells by inhibiting CSF-1/PI3K/AKT signaling pathway.

Background: The interaction between cancer cells and the tumor microenvironment is of critical importance in liver cancer. Jiedu Granule formula (JDF) has been shown to minimize the risk of recurrence and metastasis following liver cancer resection. Investigating the mechanism underlying the therapeutic effects of JDF can extend its field of application and develop novel treatment approaches. Methods: We established a rat liver orthotopic transplantation tumor model, and recorded the prognostic effects of JDF adjuvant therapy on the recurrence and metastasis of liver cancer. Liver and lung tissues were collected for immunofluorescence staining and H&E staining, respectively. In addition, THP-1 cells were incubated with PMA and IL-4 to induce them to differentiate into M2 macrophages. CSF-1 expression was knocked down using lentivirus to determine the function of CSF-1. Liver cancer cells were cultured with a conditioned medium (CM) or co-cultured with macrophages. Cell viability was determined using the MTT assay. The levels of CSF-1, CSF-1R, E-cadherin, N-cadherin, PI3K, AKT, and cleaved caspase-3 were detected using ELISA, Western blotting and qPCR. The ability of cells to migrate was assessed using cell scratch and transwell assays. Apoptosis was evaluated using flow cytometry. Results: The JDF treatment decreased the risk of liver cancer metastasis after surgery and the infiltration of CD206/CD68 cells in liver cancer tissue. In cell experiments, JDF showed effects in suppressing M2 macrophages activity and downregulating the expression of CSF-1 and CSF-1R. The concentration of CSF-1 in the supernatant was also lower in the JDF-treated group. Futhermore, M2-CM was found to promote cancer cell migration and epithelial-mesenchymal transition (EMT); however, these effects were weakened after administering JDF. Knocking down endogenous CSF-1 in M2 macrophages resulted in a comparable suppression of cancer cell migration and EMT. Additionally, JDF treatment inhibited activation of the PI3K/AKT pathway, thus promoting the apoptosis of M2 macrophages. Conclusions: Treatment with JDF reduced the EMT and migratory capacity of liver cancer cells, which might be attributed to the inhibition of M2 macrophage infiltration and interruption of the CSF-1/PI3K/AKT signaling pathway. This mechanism may hold significant implications for mitigating the risk of metastatic spread in the aftermath of hepatic surgery.

LncRNA018392 promotes the proliferation of Liaoning cashmere goat skin fibroblasts by upregulating CSF1R through binding to SPI1.

BACKGROUND: Liaoning cashmere goat is recognized as a valuable genetic resource breed, with restrictions on genetic outflow in China. Hair follicle development in the cashmere goat is influenced by melatonin and long non-coding RNAs (lncRNAs). However, the role of lncRNAs in facilitating melatonin-promoted cashmere growth remains poorly understood. Previous studies have identified a new lncRNA, lncRNA018392, which is involved in the melatonin-promoted proliferation of cashmere skin fibroblasts. METHOD: Flow cytometry and CCK-8 assays confirmed that silencing lncRNA018392 negates the effects of melatonin on cell proliferation, and that proliferation was reduced when the gene CSF1R, located near lncRNA018392, was inhibited. Further investigation using a dual-luciferase reporter assay showed that lncRNA018392 could positively regulate the promoter of CSF1R. RESULTS: Results from RNA-binding protein immunoprecipitation (RIP) and chromatin immunoprecipitation sequencing (ChIP-Seq) revealed that lncRNA018392 interacts with the transcription factor SPI1, with CSF1R being a downstream target gene regulated by SPI1. This interaction was confirmed by ChIP-PCR, which demonstrated SPI1's binding to CSF1R. CONCLUSIONS: This study found that the melatonin-responsive lncRNA018392 accelerates the cell cycle and promotes cell proliferation by recruiting SPI1 to upregulate the expression of the neighboring gene CSF1R. These findings provide a theoretical foundation for elucidating the molecular mechanisms of cashmere growth and for the molecular breeding of cashmere goats.

Brain volume and microglial density changes are correlated in a juvenile mouse model of cranial radiation and CSF1R inhibitor treatment.

Microglia have been shown to proliferate and become activated following cranial radiotherapy (CRT), resulting in a chronic inflammatory response. We investigated the role of microglia in contributing to widespread volume losses observed in the brain following CRT in juvenile mice. To manipulate microglia, we used low-dose treatment with a highly selective CSF1R inhibitor called PLX5622 (PLX). We hypothesized that alteration of the post-CRT microglia population would lead to changes in brain development outcomes, as evaluated by structural MRI. Wild-type C57BL/6J mice were provided with daily intraperitoneal injections of PLX (25 mg/kg) or vehicle from postnatal day (P)14 to P19. Mice also received whole-brain irradiation (7 Gy) or sham irradiation (0 Gy) at 16 days of age. In one cohort of mice, immunohistochemical assessment in tissue sections was conducted to assess the impact of the selected PLX and CRT doses as well as their combination. In a separate cohort, mice were imaged using MRI at P14 (pretreatment), P19, P23, P42 and P63 in order to assess induced volume changes, which were measured based on structures from a predefined atlas. We observed that PLX and radiation treatments led to sex-specific changes in the microglial cell population. Across treatment groups, MRI-detected anatomical volumes at P19 and P63 were associated with microglia and proliferating microglia densities, respectively. Overall, our study demonstrates that low-dose PLX treatment produces a sex-dependent response in juvenile mice, that manipulation of microglia alters CRT-induced volume changes and that microglia density and MRI-derived volume changes are correlated in this model.

Suppression of inner blood-retinal barrier breakdown and pathogenic Müller glia activation in ischemia retinopathy by myeloid cell depletion.

Ischemic retinopathies including diabetic retinopathy are major causes of vision loss. Inner blood-retinal barrier (BRB) breakdown with retinal vascular hyperpermeability results in macular edema. Although dysfunction of the neurovascular unit including neurons, glia, and vascular cells is now understood to underlie this process, there is a need for fuller elucidation of the underlying events in BRB dysfunction in ischemic disease, including a systematic analysis of myeloid cells and exploration of cellular cross-talk. We used an approach for microglia depletion with the CSF-1R inhibitor PLX5622 (PLX) in the retinal ischemia-reperfusion (IR) model. Under non-IR conditions, PLX treatment successfully depleted microglia in the retina. PLX suppressed the microglial activation response following IR as well as infiltration of monocyte-derived macrophages. This occurred in association with reduction of retinal expression of chemokines including CCL2 and the inflammatory adhesion molecule ICAM-1. In addition, there was a marked suppression of retinal neuroinflammation with reduction in expression of IL-1b, IL-6, Ptgs2, TNF-a, and Angpt2, a protein that regulates BRB permeability. PLX treatment significantly suppressed inner BRB breakdown following IR, without an appreciable effect on neuronal dysfunction. A translatomic analysis of Müller glial-specific gene expression in vivo using the Ribotag approach demonstrated a strong suppression of Müller cell expression of multiple pro-inflammatory genes following PLX treatment. Co-culture studies of Müller cells and microglia demonstrated that activated microglia directly upregulates Müller cell-expression of these inflammatory genes, indicating Müller cells as a downstream effector of myeloid cells in retinal IR. Co-culture studies of these two cell types with endothelial cells demonstrated the ability of both activated microglia and Müller cells to compromise EC barrier function. Interestingly, quiescent Müller cells enhanced EC barrier function in this co-culture system. Together this demonstrates a pivotal role for myeloid cells in inner BRB breakdown in the setting of ischemia-associated disease and indicates that myeloid cells play a major role in iBRB dysregulation, through direct and indirect effects, while Müller glia participate in amplifying the neuroinflammatory effect of myeloid cells.

Phagocytosis Checkpoints in Glioblastoma: CD47 and Beyond.

Glioblastoma multiforme (GBM) is one of the deadliest human cancers with very limited treatment options available. The malignant behavior of GBM is manifested in a tumor which is highly invasive, resistant to standard cytotoxic chemotherapy, and strongly immunosuppressive. Immune checkpoint inhibitors have recently been introduced in the clinic and have yielded promising results in certain cancers. GBM, however, is largely refractory to these treatments. The immune checkpoint CD47 has recently gained attention as a potential target for intervention as it conveys a "don't eat me" signal to tumor-associated macrophages (TAMs) via the inhibitory SIRP alpha protein. In preclinical models, the administration of anti-CD47 monoclonal antibodies has shown impressive results with GBM and other tumor models. Several well-characterized oncogenic pathways have recently been shown to regulate CD47 expression in GBM cells and glioma stem cells (GSCs) including Epidermal Growth Factor Receptor (EGFR) beta catenin. Other macrophage pathways involved in regulating phagocytosis including TREM2 and glycan binding proteins are discussed as well. Finally, chimeric antigen receptor macrophages (CAR-Ms) could be leveraged for greatly enhancing the phagocytosis of GBM and repolarization of the microenvironment in general. Here, we comprehensively review the mechanisms that regulate the macrophage phagocytosis of GBM cells.

Microglia are not necessary for maintenance of blood-brain barrier properties in health, but PLX5622 alters brain endothelial cholesterol metabolism.

Microglia, the resident immune cells of the central nervous system, are intimately involved in the brain's most basic processes, from pruning neural synapses during development to preventing excessive neuronal activity throughout life. Studies have reported both helpful and harmful roles for microglia at the blood-brain barrier (BBB) in the context of disease. However, less is known about microglia-endothelial cell interactions in the healthy brain. To investigate the role of microglia at a healthy BBB, we used the colony-stimulating factor 1 receptor (CSF1R) inhibitor PLX5622 to deplete microglia and analyzed the BBB ultrastructure, permeability, and transcriptome. Interestingly, we found that, despite their direct contact with endothelial cells, microglia are not necessary for the maintenance of BBB structure, function, or gene expression in the healthy brain. However, we found that PLX5622 treatment alters brain endothelial cholesterol metabolism. This effect was independent from microglial depletion, suggesting that PLX5622 has off-target effects on brain vasculature.

The Novel-m0230-3p miRNA Modulates the CSF1/CSF1R/Ras Pathway to Regulate the Cell Tight Junctions and Blood-Testis Barrier in Yak.

The yak (Bos grunniens) is a valuable livestock animal endemic to the Qinghai-Tibet Plateau in China with low reproductive rates. Cryptorchidism is one of the primary causes of infertility in male yaks. Compared with normal testes, the tight junctions (TJs) of Sertoli cells (SCs) and the integrity of the blood-testis barrier (BTB) in cryptorchidism are both disrupted. MicroRNAs are hairpin-derived RNAs of about 19-25 nucleotides in length and are involved in a variety of biological processes. Numerous studies have shown the involvement of microRNAs in the reproductive physiology of yak. In this study, we executed RNA sequencing (RNA-seq) to describe the expression profiles of mRNAs and microRNAs in yaks with normal testes and cryptorchidism to identify differentially expressed genes. GO and KEGG analyses were used to identify the biological processes and signaling pathways which the target genes of the differentially expressed microRNAs primarily engaged. It was found that novel-m0230-3p is an important miRNA that significantly differentiates between cryptorchidism and normal testes, and it is down-regulated in cryptorchidism with p < 0.05. Novel-m0230-3p and its target gene CSF1 both significantly contribute to the regulation of cell adhesion and tight junctions. The binding sites of novel-m0230-3p with CSF1 were validated by a dual luciferase reporter system. Then, mimics and inhibitors of novel-m0230-3p were transfected in vitro into SCs, respectively. A further analysis using qRT-PCR, immunofluorescence (IF), and Western blotting confirmed that the expression of cell adhesion and tight-junction-related proteins Occludin and ZO-1 both showed changes. Specifically, both the mRNA and protein expression levels of Occludin and ZO-1 in SCs decreased after transfection with the novel-m0230-3p mimics, while they increased after transfection with the inhibitors, with p < 0.05. These were achieved via the CSF1/CSF1R/Ras signaling pathway. In summary, our findings indicate a negative miRNA-mRNA regulatory network involving the CSF1/CSF1R/Ras signaling pathway in yak SCs. These results provide new insights into the molecular mechanisms of CSF1 and suggest that novel-m0230-3p and its target protein CSF1 could be used as potential therapeutic targets for yak cryptorchidism.

Emerging Microglial Therapies and Targets in Clinical Trial.

Modulation of microglia function for treatment of neurodegenerative and neuropsychiatric disorders is an emerging field of neuroscience drug development. This is largely attributed to human genetic association studies combined with biological evidence indicating that the innate immune system acts as a causal contributor superimposed on the reactive component of neuronal loss in neurological dysfunction. The identification of disease risk gene variants that encode immune-modulatory proteins in microglia provides tools to evaluate how microglia cellular function or dysfunction affect neuronal health. The development of clinical stage therapeutic compounds that modify myeloid cell function enables us to investigate how modulating microglia function could become a transformational approach to mitigate neurological disorders. Improving our ability to boost microglia-promoting homeostatic and reparative functions hopefully will translate into achieving a better outcome for patients affected by neurological diseases. In this chapter, we aim to provide an overview of the microglial emerging therapies and targets being studied in current clinical trials.

Deciphering glial contributions to CSF1R-related disorder via single-nuclear transcriptomic profiling: a case study.

CSF1R-related disorder (CSF1R-RD) is a neurodegenerative condition that predominantly affects white matter due to genetic alterations in the CSF1R gene, which is expressed by microglia. We studied an elderly man with a hereditary, progressive dementing disorder of unclear etiology. Standard genetic testing for leukodystrophy and other neurodegenerative conditions was negative. Brain autopsy revealed classic features of adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP), including confluent white matter degeneration with axonal spheroids and pigmented glial cells in the affected white matter, consistent with CSF1R-RD. Subsequent long-read sequencing identified a novel deletion in CSF1R that was not detectable with short-read exome sequencing. To gain insight into potential mechanisms underlying white matter degeneration in CSF1R-RD, we studied multiple brain regions exhibiting varying degrees of white matter pathology. We found decreased CSF1R transcript and protein across brain regions, including intact white matter. Single nuclear RNA sequencing (snRNAseq) identified two disease-associated microglial cell states: lipid-laden microglia (expressing GPNMB, ATG7, LGALS1, LGALS3) and inflammatory microglia (expressing IL2RA, ATP2C1, FCGBP, VSIR, SESN3), along with a small population of CD44+ peripheral monocyte-derived macrophages exhibiting migratory and phagocytic signatures. GPNMB+ lipid-laden microglia with ameboid morphology represented the end-stage disease microglia state. Disease-associated oligodendrocytes exhibited cell stress signatures and dysregulated apoptosis-related genes. Disease-associated oligodendrocyte precursor cells (OPCs) displayed a failure in their differentiation into mature myelin-forming oligodendrocytes, as evidenced by upregulated LRP1, PDGFRA, SOX5, NFIA, and downregulated NKX2-2, NKX6.2, SOX4, SOX8, TCF7L2, YY1, ZNF488. Overall, our findings highlight microglia-oligodendroglia crosstalk in demyelination, with CSF1R dysfunction promoting phagocytic and inflammatory microglia states, an arrest in OPC differentiation, and oligodendrocyte depletion.

Novel variants in CSF1R associated with adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP).

The CSF1R gene, located on chromosome 5, encodes a 108 kDa protein and plays a critical role in regulating myeloid cell function. Mutations in CSF1R have been identified as a cause of a rare white matter disease called adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP, also known as CSF1R-related leukoencephalopathy), characterized by progressive neurological dysfunction. This study aimed to broaden the genetic basis of ALSP by identifying novel CSF1R variants in patients with characteristic clinical and imaging features of ALSP. Genetic analysis was performed through whole-exome sequencing or panel analysis for leukodystrophy genes. Variant annotation and classification were conducted using computational tools, and the identified variants were categorized following the recommendations of the American College of Medical Genetics and Genomics (ACMG). To assess the evolutionary conservation of the novel variants within the CSF1R protein, amino acid sequences were compared across different species. The study identified six previously unreported CSF1R variants (c.2384G>T, c.2133_2919del, c.1837G>A, c.2304C>A, c.2517G>T, c.2642C>T) in seven patients with ALSP, contributing to the expanding knowledge of the genetic diversity underlying this rare disease. The analysis revealed considerable genetic and clinical heterogeneity among these patients. The findings emphasize the need for a comprehensive understanding of the genetic basis of rare diseases like ALSP and underscored the importance of genetic testing, even in cases with no family history of the disease. The study's contribution to the growing spectrum of ALSP genetics and phenotypes enhances our knowledge of this condition, which can be crucial for both diagnosis and potential future treatments.

CSF1R inhibition depletes brain macrophages and reduces brain virus burden in SIV-infected macaques.

Perivascular macrophages (PVMs) and, to a lesser degree, microglia are targets and reservoirs of HIV and simian immunodeficiency virus (SIV) in the brain. Previously, we demonstrated that colony-stimulating factor 1 receptor (CSF1R) in PVMs was upregulated and activated in chronically SIV-infected rhesus macaques with encephalitis, correlating with SIV infection of PVMs. Herein, we investigated the role of CSF1R in the brain during acute SIV infection using BLZ945, a brain-penetrant CSF1R kinase inhibitor. Apart from three uninfected historic controls, nine Indian rhesus macaques were infected acutely with SIVmac251 and divided into three groups (n = 3 each): an untreated control and two groups treated for 20-30 days with low- (10 mg/kg/day) or high- (30 mg/kg/day) dose BLZ945. With the high-dose BLZ945 treatment, there was a significant reduction in cells expressing CD163 and CD206 across all four brain areas examined, compared with the low-dose treatment and control groups. In 9 of 11 tested regions, tissue viral DNA (vDNA) loads were reduced by 95%-99% following at least one of the two doses, and even to undetectable levels in some instances. Decreased numbers of CD163+ and CD206+ cells correlated significantly with lower levels of vDNA in all four corresponding brain areas. In contrast, BLZ945 treatment did not significantly affect the number of microglia. Our results indicate that doses as low as 10 mg/kg/day of BLZ945 are sufficient to reduce the tissue vDNA loads in the brain with no apparent adverse effect. This study provides evidence that infected PVMs are highly sensitive to CSF1R inhibition, opening new possibilities to achieve viral clearance.

Pexidartinib and Immune Checkpoint Inhibitors Combine to Activate Tumor Immunity in a Murine Colorectal Cancer Model by Depleting M2 Macrophages Differentiated by Cancer-Associated Fibroblasts.

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.

Redefining the ontogeny of hyalocytes as yolk sac-derived tissue-resident macrophages of the vitreous body.

BACKGROUND: The eye is a highly specialized sensory organ which encompasses the retina as a part of the central nervous system, but also non-neural compartments such as the transparent vitreous body ensuring stability of the eye globe and a clear optical axis. Hyalocytes are the tissue-resident macrophages of the vitreous body and are considered to play pivotal roles in health and diseases of the vitreoretinal interface, such as proliferative vitreoretinopathy or diabetic retinopathy. However, in contrast to other ocular macrophages, their embryonic origin as well as the extent to which these myeloid cells might be replenished by circulating monocytes remains elusive. RESULTS: In this study, we combine transgenic reporter mice, embryonic and adult fate mapping approaches as well as parabiosis experiments with multicolor immunofluorescence labeling and confocal laser-scanning microscopy to comprehensively characterize the murine hyalocyte population throughout development and in adulthood. We found that murine hyalocytes express numerous well-known myeloid cell markers, but concomitantly display a distinct immunophenotype that sets them apart from retinal microglia. Embryonic pulse labeling revealed a yolk sac-derived origin of murine hyalocytes, whose precursors seed the developing eye prenatally. Finally, postnatal labeling and parabiosis established the longevity of hyalocytes which rely on Colony Stimulating Factor 1 Receptor (CSF1R) signaling for their maintenance, independent of blood-derived monocytes. CONCLUSION: Our study identifies hyalocytes as long-living progeny of the yolk sac hematopoiesis and highlights their role as integral members of the innate immune system of the eye. As a consequence of their longevity, immunosenescence processes may culminate in hyalocyte dysfunction, thereby contributing to the development of vitreoretinal diseases. Therefore, myeloid cell-targeted therapies that convey their effects through the modification of hyalocyte properties may represent an interesting approach to alleviate the burden imposed by diseases of the vitreoretinal interface.

Targeting CSF1R in myeloid-derived suppressor cells: insights into its immunomodulatory functions in colorectal cancer and therapeutic implications.

OBJECTIVE: This study aimed to investigate the critical role of MDSCs in CRC immune suppression, focusing on the CSF1R and JAK/STAT3 signaling axis. Additionally, it assessed the therapeutic efficacy of LNCs@CSF1R siRNA and anti-PD-1 in combination. METHODS: Single-cell transcriptome sequencing data from CRC and adjacent normal tissues identified MDSC-related differentially expressed genes. RNA-seq analysis comprehensively profiled MDSC gene expression in murine CRC tumors. LNCs@CSF1R siRNA nanocarriers effectively targeted and inhibited CSF1R. Flow cytometry quantified changes in MDSC surface markers post-CSF1R inhibition. RNA-seq and pathway enrichment analyses revealed the impact of CSF1R on MDSC metabolism and signaling. The effect of CSF1R inhibition on the JAK/STAT3 signaling axis was validated using Colivelin and metabolic assessments. Glucose and fatty acid uptake were measured via fluorescence-based flow cytometry. The efficacy of LNCs@CSF1R siRNA and anti-PD-1, alone and in combination, was evaluated in a murine CRC model with extensive tumor section analyses. RESULTS: CSF1R played a significant role in MDSC-mediated immune suppression. LNCs@CSF1R siRNA nanocarriers effectively targeted MDSCs and inhibited CSF1R. CSF1R regulated MDSC fatty acid metabolism and immune suppression through the JAK/STAT3 signaling axis. Inhibition of CSF1R reduced STAT3 activation and target gene expression, which was rescued by Colivelin. Combined treatment with LNCs@CSF1R siRNA and anti-PD-1 significantly slowed tumor growth and reduced MDSC abundance within CRC tumors. CONCLUSION: CSF1R via the JAK/STAT3 axis critically regulates MDSCs, particularly in fatty acid metabolism and immune suppression. Combined therapy with LNCs@CSF1R siRNA and anti-PD-1 enhances therapeutic efficacy in a murine CRC model, providing a strong foundation for future clinical applications.

Microglia contribute to nociception via CSF-1R signaling pathway in rat orofacial carcinoma.

OBJECTIVE: Cancer-induced pain is the most common complication of the head and neck cancer. The microglia colony-stimulating factor receptor 1 (CSF1R) plays a crucial role in the inflammation and neuropathic pain. However, the effect of CSF1R on orofacial cancer-induced pain is unclear. Here, we aimed to determine the role of CSF1R in orofacial pain caused by cancer. METHODS: We established an animal model of cancer-induced orofacial pain with Walker 256B cells. Von Frey filament test and laser-intensity pain tester were used to evaluate tumor-induced mechanical and thermal hypersensitivity. Minocycline and PLX3397 were used to alter tumor-induced mechanical and thermal hyperalgesia. Additionally, we evaluated the effect of PLX3397 on immunoinflammatory mediators and neuronal activation within the trigeminal spinal subnucleus caudalis (Vc). RESULTS: Walker 256B cell-induced tumor growth resulted in mechanical and thermal hyperalgesia, accompanying by microglia activation and CSF1R upregulation. Treatment with minocycline or PLX3397 reversed the associated nocifensive behaviors and microglia activation triggered by tumor. As a result of PLX3397 treatment, tumor-induced increases in pro-inflammatory cytokine expression and neuronal activation of the Vc were significantly inhibited. CONCLUSIONS: The results of our study showed that blocking microglial activation via CSF1R may help prevent cancer-induced orofacial pain.