Targeted enhancement of antigen cross-presentation capability of M2-like tumor-associated macrophages to boost glioblastoma immunotherapy.

To monitor the progression of chronic kidney disease to kidney failure is a pressing clinical challenge given its increasing incidence. In a retrospective cohort of 764 patients admitted to our hospital between June 2021 and June 2024, we performed a comprehensive analysis of serum complement C3/C4 levels. Longitudinal assessment revealed a progressive, dose-dependent decline in serum C3 that correlated with disease advancement from renal insufficiency to chronic renal failure and ultimately to kidney failure. To further investigate the role of C3, we utilized an adenine-induced nephropathy model in mice. C3-/- (C3-deficient) mice exhibited heightened susceptibility to renal injury, reflected by significant elevations in urea, uric acid, and creatinine levels. Flow cytometric analysis showed an 11% reduction in renal CD19+ B cell infiltration in C3-/- mice compared with wild-type controls. Mechanistically, C3 promotes B cell recruitment via the CD21/CD35 complement receptors, and these recruited B cells upregulate IL-10 to exert a renoprotective effect. Logistic regression identified serum C3 as a candidate predictive biomarker for distinguishing kidney failure. Serum C3 may represent a candidate biomarker worthy of further prospective validation for tracking the progression of CKD. Our research findings are expected to establish a novel prognostic framework for risk stratification of CKD patients through continuous serum C3 monitoring, offering a critical window for early intervention in end-stage renal disease.

Background Medicinal mushrooms have a long history of use in traditional medicine and are increasingly investigated in modern oncology as supportive care agents. In recent decades, clinical research has explored their immunomodulatory properties and potential to mitigate chemotherapy-related adverse effects when used as adjuncts to conventional cancer treatment. Objective This review aims to critically evaluate the clinical evidence supporting the use of medicinal mushrooms in oncology, with particular emphasis on immunological modulation, treatment tolerability, safety, and their integration with chemotherapy. Methods A narrative review of clinical trials, cohort studies, systematic reviews, and meta-analyses was conducted. The literature search was conducted in PubMed, Scopus and Google Scholar. Studies published between 2000 to 2026 were considered, Clinical trials, experimental studies and relevant review articles focusing on medicinal mushrooms, chemotherapy and cancer-related mechanisms were included. Mushroom focusing on species with documented clinical evaluation in cancer patients, including Trametes versicolor (L.) Lloyd (Turkey tail), Lentinula edodes (Berk.) Pegler (Shiitake), Grifola frondosa (Dicks.) Gray (Maitake), Ganoderma lucidum (Fr.) Karst. (Reishi), Cordyceps species, Pleurotus species , and selected additional fungi. Outcomes assessed included immune parameters, hematological indices, quality of life, chemotherapy tolerance, and safety. Results Clinical evidence indicates that polysaccharide-rich mushroom extracts exert immunomodulatory effects through interactions with innate immune receptors such as Dectin-1 and complement receptor 3, leading to enhanced natural killer cell activity, improved antigen presentation, and modulation of Th1-associated immune responses. Adjunctive use during chemotherapy is associated with favorable trends in immune preservation, reduced severity of myelosuppression, mitigation of gastrointestinal and systemic inflammatory effects, and improvements in patient-reported quality of life. Serious adverse events are rare, and standardized mushroom preparations demonstrate a favorable safety profile when used appropriately. Conclusion Medicinal mushrooms should be viewed as supportive, rather than cytotoxic, interventions in oncology. When integrated responsibly alongside chemotherapy, selected mushroom extracts may enhance immune resilience, improve treatment tolerability, and support continuity of care. Although evidence is strongest for specific compounds such as PSK and lentinan, further high-quality randomized trials and standardized formulations are required to clarify optimal use and define their role within evidence-based integrative oncology.

Primary gastric lymphoma (PGL) is a rare form of lymphoma that arises within the gastric mucosa-associated lymphoid tissue (MALT), often linked to Helicobacter pylori (Hp) infection. The endoscopic features of PGL are heterogeneous, and understanding these characteristics could help distinguish between different lymphoma subtypes. This study aims to systematically assess the endoscopic features of PGL and explore the role of complement receptor type 2/B-cell lymphoma 6 protein (CD21/BCL6)-based grading of lymphoid follicular disruption in predicting the effectiveness of Hp eradication (HPE) treatment in gastric MALT lymphoma. A retrospective study was conducted involving 100 patients diagnosed with PGL at Peking University Third Hospital between January 2010 and January 2025. Patients were divided into two groups based on histopathological findings: indolent and aggressive lymphoma. The clinical and endoscopic characteristics of these two groups were compared. Survival analysis, including overall survival (OS) and progression-free survival (PFS), was performed using Kaplan-Meier curves and Log-rank tests. A subgroup of 25 patients with gastric MALT lymphoma and known HPE outcomes was selected for further analysis. Diagnostic biopsies were immunohistochemically stained with CD21 and BCL6 and graded from G0 to G4 based on follicular disruption. Logistic regression analysis was used to identify factors associated with HPE failure. Among the 100 patients, the average age was 63.0 (55.8, 71.0) years, with 47 men and 53 women. Aggressive lymphoma showed a significantly higher incidence of B symptoms compared with indolent lymphoma (49.0% vs. 19.6%, P= 0.004). Endoscopically, aggressive lymphoma presented more frequently with ulcerative or mixed morphologies (P < 0.001) and exhibited higher rates of mucosal erosion, ulceration with white slough, lesion friability, bleeding tendency, gastric stenosis, and impaired peristalsis (P < 0.001 for all). Aggressive lymphoma also had significantly worse OS and PFS (OS: P=0.009; PFS: P=0.003). In the subgroup of 25 MALT lymphoma patients, those with ineffective HPE were more likely to be Hp-negative (P=0.049) and had a significantly higher degree of follicular disruption (P=0.015). Multivariable Logistic regression revealed that follicular disruption grading was independently associated with HPE failure (AOR=3.63, 95%CI: 1.14-11.58, P=0.021), while Hp infection status was not (P=0.240). PGL demonstrates considerable variability in its endoscopic presentation. Features, such as ulcerative/mixed morphology, friability, bleeding tendency, stenosis, and impaired peristalsis are indicative of more aggressive disease and correlate with poorer survival outcomes. The CD21/BCL6-based grading of lymphoid follicular disruption provides a valuable tool for identifying patients at high risk of HPE failure, supporting early intervention and risk stratification for gastric MALT lymphoma treatment.

Liver diseases, ranging from chronic hepatitis and metabolic dysfunction to cirrhosis and hepatocellular carcinoma, represent a major global public health burden. As an immune-privileged organ, the liver harbors a unique and intricate immune microenvironment, which plays a dual role in pathogen clearance and chronicity. Kupffer cells (KCs), the primary resident macrophages in the liver, constitute the first line of defense in liver innate immunity and play complex and important roles in pathogen recognition, phagocytosis, and the regulation of liver inflammation and immune responses. The complement receptor of the immunoglobulin superfamily (CRIg) is a membrane receptor that is specifically expressed on KCs. It serves not only as a sentinel for the liver against pathogen invasion but also as a sophisticated regulator for maintaining immune homeostasis. As a key component of the liver's immune system, CRIg can efficiently mediate the clearance of complement-opsonized particles, thereby playing multidimensional roles in pathogen clearance, antigen cross-presentation, and the establishment of immune tolerance, functioning as both a "pathogen catcher" and an "immune brake." This review focuses on the CRIg molecule, detailing its mechanisms in the recognition and phagocytic clearance by KCs, and its subsequent impact on hepatic immune responses. Furthermore, we explored the potential involvement of CRIg in the pathological progression of diverse liver diseases, including persistent inflammation, fibrosis, and hepatocarcinogenesis. This synthesis provides novel insights into the immunopathology of liver diseases and establishes a theoretical foundation for developing CRIg-targeted therapeutic strategies.

Introduction Macrophage phagocytosis is a major cytotoxic mechanism for therapeutic monoclonal antibodies (mAbs) that opsonize target cells. This antibody-dependent cellular phagocytosis (ADCP) can occur via the Fcγ or complement pathways, but the relative contribution of these pathways to mAb-mediated cell clearance is not known. Here, we analyzed the kinetics, functional cooperation, and phagocytic capacities of Fcγ receptor-dependent and complement-dependent ADCP, separately and concomitantly, in primary macrophages challenged with mAb-opsonized lymphocytes. Methods Using quantitative live-cell imaging of primary mouse macrophages, genetic disruption of Fcγ receptor signaling, and controlled modulation of complement activity, we directly compared the kinetics, capacity, and exhaustion behavior of ADCP via the Fcγ (fADCP) and complement (cADCP) pathways. Results cADCP operates as a mechanistically independent phagocytic pathway with distinct temporal dynamics. Relative to fADCP, cADCP exhibits delayed onset but substantially greater cumulative target clearance. When both pathways are engaged simultaneously, their effects on target removal are additive, indicating functional non-redundancy. Notably, macrophages rendered refractory to further phagocytosis following fADCP retain full capacity for cADCP, demonstrating that complement receptor–mediated engulfment can bypass Fcγ receptor–associated hypophagia. However, despite its greater capacity, cADCP is also finite, as increasing target burden induces a dose-dependent state of complement-associated phagocytic exhaustion that is kinetically distinct from fADCP hypophagia and is largely reversible within 24 h. Discussion Our mechanistic understanding of mAb-mediated cytotoxicity via ADCP is disproportionately focused on Fcγ receptor engagement and signaling, with comparatively less emphasis on the role of complement activation. These findings establish complement-mediated ADCP as a quantitatively powerful macrophage effector pathway that can be leveraged to enhance the overall cytotoxic efficacy of mAbs. Further, our work provides a functional framework for understanding how Fcγ receptor and complement pathways differentially contribute to macrophage cytotoxic capacity and highlights effector exhaustion as a shared but mechanistically distinct constraint on sustained antibody-mediated cell clearance. Effector exhaustion therefore represents a fundamental bottleneck to durable responses to ADCP-inducing therapeutic antibodies, but one that can potentially be mitigated via utilization of both ADCP pathways.

Pulmonary fibrosis (PF), the irreversible scarring of the lungs in many interstitial lung diseases, remains fatal despite currently approved antifibrotic therapy. Converging evidence shows that dysregulated innate and adaptive immunity orchestrates every stage of the fibrotic cascade. Roughly 20% of PF susceptibility loci map to immune regulatory genes, including Toll-interacting protein, interleukin (IL)-1 receptor antagonist, Toll-like receptor-3, complement receptor-1 and tumour necrosis factor-α (TNF-α), indicating that genetically primed host defence pathways predispose to maladaptive repair. Recurrent epithelial injury triggers a type 1 inflammatory response that gradually shifts toward type 2-skewed wound healing; the resulting cytokine milieu rich in transforming growth factor-β, IL-13, IL-6 and platelet-derived growth factor reprogrammes fibroblasts into collagen-secreting myofibroblasts. Spatial-omic profiling of PF lungs corroborates this model, revealing niches where profibrotic macrophages, T-helper cells and inflammatory fibroblasts colocalise within a stiff, collagen-rich matrix. Beyond their direct antimesenchymal actions, the current therapeutics pirfenidone and nintedanib also temper innate and adaptive immune signalling. Proof of concept for sharper immunomodulation now comes from recent phase III trials of nerandomilast, a highly selective phosphodiesterase-4B inhibitor that preserved forced vital capacity and downregulated TNF-α, IL-6 and IL-17 networks. These results demonstrate that immune pathway modulation can complement existing antifibrotics and invigorate efforts to align mechanism-based therapies with patient-specific immune endotypes, steered by genetics, cellular phenotypes and circulating biomarkers. This review synthesises current understanding of how immunity initiates, amplifies and perpetuates PF, linking genetic and mechanistic insights to emerging therapeutic opportunities. A deeper grasp of immune-epithelial-fibroblast crosstalk is essential for transforming disease-slowing care into genuinely disease-modifying intervention.

C3a-C3ar1 axis mediates macrophage M1 polarization to drive silicosis inflammation and fibrosis.

WCN26-6131 THE ROLE OF COMPLEMENT RECEPTOR CR4-POSITIVE MACROPHAGES IN ENDOCAPPILLALY PROLIFERATIVE GLOMEULAR LESIONS OF CHRONIC GLOMERULONEPHRITIS

High-expression variants of the complement C4 gene increase schizophrenia (SZ) risk. C4 overexpression (C4-OE) in the mouse frontal cortex recapitulates SZ-associated phenotypes, including lower synapse density, but the underlying mechanisms remain unclear. In the complement cascade, C4 is upstream of C3, whose cleavage fragments can bind complement receptors, including CR3, selectively expressed by microglia in the brain parenchyma. Therefore, we hypothesize that microglial CR3 mediates C4-OE effects. We show that C4-OE alters synapse density and function and that these effects are rescued in CR3-deficient mice. Contrary to the models of excessive microglia-mediated synaptic elimination, our previous results indicate that C4-OE reduces spine formation and elimination. Here, using in vivo two-photon imaging, we find that C4-OE decreases microglial surveilled volume, motility, and the frequency of microglial contacts with pre- and postsynaptic structures. These changes are abolished by CR3 deficiency. Our findings suggest that CR3-mediated modulation of microglia-synapse interactions underlies C4-OE effects relevant to SZ.

Pan-cancer macrophage atlas uncovers that MHC-IIhigh TAMs induce Treg activation through physical interactions.

Although systemic inflammation has been implicated in PD pathogenesis, the underlying mechanisms remain poorly understood. In this study, we investigate the pathological events in a systemic inflammation-induced PD mouse model. We demonstrate that synaptic loss in the midbrain occurs as early as 1 day after the final lipopolysaccharide (LPS) administration, preceding dopaminergic (DA) neuron degeneration, which was observed only at later stages (14 days). Early microglial activation in the midbrain is detected, accompanied by excessive synaptic engulfment, suggesting a critical role of microglia-dependent synapse elimination in PD pathogenesis. Furthermore, we identify the complement receptor 3 (CR3) as a key mediator of microglial synaptic engulfment, revealing that its inhibition rescues synaptic integrity and prevents neurodegeneration. Our results contribute to a deeper understanding of early events of PD progression driven by systemic inflammation and provide early intervention strategies targeting microglial complement signaling to halt PD progression.

Cerebrovascular disruption has been implicated in the pathophysiology of head trauma and chronic traumatic encephalopathy (CTE). However, the long-term consequences of repetitive head trauma on blood-brain barrier (BBB) integrity and its link to cognitive function remain unknown. Here, using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), we show that BBB disruption can be detected years after the retirement of combat and collision sports athletes (n = 47) from their respective sports. A subgroup of individuals (n = 17) with extensive BBB disruption displayed worse cognitive decline compared with those with less extensive BBB disruption. Commonly used systemic markers of central nervous system injury and neurodegeneration were of limited utility; however, a greater systemic inflammatory burden with a higher proportion of circulating monocytes was associated with cognitive decline in the retired athletes. Transcriptomic analysis of these peripheral immune cells revealed dysregulation of the complement system and vascular developmental pathways. Altered expression of complement receptors, including C5AR1, ITGAM, ITGB2, and CD59, a potent inhibitor of the membrane attack complex (MAC), was associated with BBB disruption and cognitive decline. Postmortem brain tissues from those with confirmed cases of CTE showed MAC deposition around cerebral blood vessels. Bioinformatic analysis of single-nucleus RNA sequencing data from postmortem individuals with CTE revealed microglia-endothelial cross-talk, which may mediate complement dysregulation. Together, our data suggest that sustained systemic inflammation and persistent BBB disruption are associated with the long-term outcome of repetitive head trauma.

The complement receptor immunoglobulin (CRIg), a key microbial pathogen phagocytosis-promoting receptor, responsible for intravascular clearance of bacteria, is purported to be expressed selectively on tissue-fixed macrophages such as Kupffer cells. However, recently it has been reported that neutrophils can also express functional CRIg following activation by inflammatory mediators. Monocytes have been reported not to express CRIg under non-activated conditions. Thus, investigations were undertaken to examine whether blood monocytes express CRIg under cell activation conditions and its role in anti-microbial immunity. Monocytes CRIg expression in whole human and mouse blood or peripheral blood mononuclear cells and purified monocytes using density gradient centrifugation or anaffinity purification kit was examined using PE/FITC-labelled anti-CRIg monoclonal antibody and flow cytometry. Characterization of CRIg isoforms in monocytes was determined by the detection of CRIg mRNA transcripts and protein using RT-PCR and Western blot, respectively. Gene-edited CRIg- and CD18- monocytic THP-1 cell lines were generated to assess the role of CRIg and CD18 in cell adhesion, phagocytosis, and microbial killing. Functional assays were performed using Staphylococcus aureus as a model pathogen. CRIg was constitutively expressed, dynamically, on the surface of human and mouse blood monocytes. All three human monocyte subpopulations expressed CRIg, equally. The inability to demonstrate expression on monocytes cell surface by previous studies can be explained by its lability during blood storage and loss during monocyte isolation steps. Interestingly of the monocyte subpopulations only the classical and intermediate but not the non-classical showed a loss of CRIg expression. The data showed that loss from the surface was most likely due to relocation of the receptor intracellularly. Monocytes expressed 6 different CRIg mRNA transcripts and immunoreactive isoforms. Using CRIg- and CD18- THP-1 monocytic cells, we found that both CRIg and CD18 (CR3/CR4) were critical for cell adhesion, but for phagocytosis and killing of S. aureus, either receptor was independently effective. The data provide compelling evidence that monocytes express functional CRIg, relevant to the cells' anti-microbial role of the 'wandering' phagocyte and consolidate a view that CRIg is widely expressed in our phagocytic cell system, similar to the classical complement receptors CR3 and CR4.

Escherichia coli is a leading cause of neonatal sepsis, with infection occurring in approximately one in every 1,000 live births1,2. However, withE. coli colonization beginning soon after birth3-5 and defects in neonatal host defencematuration6-9, analternativeconsideration iswhy infection does not occur even more frequently. Here we show that newborn babies with E. coli sepsis have selectively reduced vertically transferred natural antibodies that recognize E. coli, mechanistically explaining their susceptibility to infection. Complementary preclinical studies show that preconceptual intestinal colonization with probiotic E. coli Nissle 1917 (EcN)10 primes anti-E. coli immunoglobulin G (IgG) antibodies with broad cross-reactivity to clinical isolates responsible for neonatal sepsis that override the inherent susceptibility of neonatal mice. Outer membrane protein A (OmpA) is a target of maternal IgG and is also essential for EcN colonization-induced serological immunogenicity. Upon vertical transfer to neonates, colonization-primed anti-E. coli IgG uniquely protects against infection via opsonization, requiring both complement and IgG Fc receptors. Compared with specimens fromsex and gestational age-matched healthy controlbabieswithout infection, dried blood spot specimens collected one day after birth from 100 babies with E. coli sepsis show consistently reduced IgG titres to pooled E. coli clinical isolates and OmpA, along with impaired IgG-dependent antibacterial opsonization. Together, these results demonstrate that natural infection susceptibility of neonates is efficiently rescued by anti-E. coli IgG and identify defects in pathogen-targeted vertically transferred immunity as a primary risk factor for severe invasive infection in newborn babies.

Chronic muscle pain (CMP) is highly prevalent, frequently comorbid with emotional disorders and characterized by a high risk of recurrence. Yet, the complex mechanisms underlying the generation and maintenance of CMP remain unclear, limiting the development of therapy. Here we identified suppressed glutamatergic neuronal excitability and reduced synaptic plasticity in the dorsomedial prefrontal cortex (dmPFC) of CMP rats using fiber photometry, patch-clamp, in vivo recording of field potentials and other techniques. The optochemical genetical activation of dmPFC glutamatergic neurons alleviated pain and anxiety-like behaviors. Single-cell RNA sequencing revealed a marked upregulation of proinflammatory microglia and complement receptor 3 (CR3) in the dmPFC, which correlated with reduced neuronal excitability and synaptic function. Flow cytometry and immunofluorescence further showed that hyperactive glutamatergic neurons induced microglial activation, proliferation, polarization and chemotaxis. Notably, the inhibition of microglia or knockdown of microglial CR3 restored dmPFC glutamatergic neuronal excitability and synaptic plasticity, thereby alleviating hyperalgesia and anxiety-like behaviors. This study demonstrates that microglial CR3-dependent synaptic pruning underlies suppressed glutamatergic neuronal excitability and reduced synaptic plasticity, playing a pivotal role in CMP generation and maintenance. These findings uncover novel microglia-neuron interactions and offer promising therapeutic targets for CMP and its emotional comorbid disorders. Microglial CR3-mediated synaptic pruning in the dmPFC suppresses glutamatergic neuronal excitability, contributing to chronic muscle pain generation and maintenance and represents a promising therapeutic target.

Generalized myasthenia gravis (gMG) is a chronic autoimmune neuromuscular disorder characterized by fluctuating muscle weakness and exertional fatigue, often requiring long-term immunosuppressive or biologic treatment. Although international guidelines recommend achieving minimal manifestations as the primary treatment goal, the lack of a standardized measurement approach has limited its application in clinical settings and trials. Minimal Symptom Expression (MSE), defined as a Myasthenia Gravis Activities of Daily Living (MG-ADL) score of 0 or 1, has recently emerged as a practical, patient-centric endpoint that reflects minimal functional burden and aligns with regulatory priorities around patient-reported outcomes. This position paper examines the rationale for MSE as a clinically meaningful, actionable treatment target in gMG. We summarize the strengths of the underlying MG-ADL scale and highlight phase 3 trial data showing that MSE is attainable with biologic therapies, including complement and neonatal Fc receptor inhibitors. Data also suggest that achieving MSE correlates with improvements in physician-assessed outcomes and quality of life metrics. However, inconsistencies in how sustained MSE is defined and reported limit comparability across trials. MSE, as a patient-centric endpoint, can be used alongside clinician-assessed measures and safety measures to support an integrated treatment goal that encompasses both efficacy and tolerability for the treatment of gMG. Future research should further define the clinical utility of MSE and sustained MSE and incorporate stakeholder input to validate MSE as a part of an integrated treatment goal in both clinical trials and real-world clinical practice.

BackgroundAlthough the molecular basis of Alzheimer's disease (AD) is often studied in Caucasians, its genetic basis in Bangladesh remains elusive.ObjectiveWe explored the association between single-nucleotide variants (SNVs) of Apolipoprotein E (APOE) and other genes for AD risk among Bangladeshis.MethodsWe recruited AD patients and controls aged ≥18 years and conducted next generation sequencing (NGS) to analyze ∼30 Mb of the human exome. The NGS targets ∼99% of the Consensus Coding Sequence and RefSeq annotations, along with the complete mitochondrial genome.ResultsA total of 132 (72 AD: 60 control) age- and sex-matched participants were sequenced. The average age of AD was comparable to that of controls (64.5 ± 11.3 versus 63.6 ± 9.8, p = 0.69), and the gender distribution (p = 0.49) was similar between the study groups. Following NGS analysis 23 SNVs from 16 potential genes were identified. The APOE variant rs429358 was associated with a significantly increased age- and sex- adjusted risk of AD (OR) 8.0 (95% CI: 2.3-27.9, p = 0.001) in the additive model, 10.5 (95% CI: 2.8-39.5, p < 0.001) in the dominant model, and 6.9 (95% CI: 1.8-26.9, p = 0.005) in the heterozygous genotype model, as determined using the Bonferroni adjustment method. The top SNV for predicting AD was the APOE variant rs429358 with a -logP value of 3, followed by BDNF gene variant rs6265 at 1.3, and CR1 gene variant rs1349409945 at 1.2.ConclusionsThe APOE variant rs429358 is linked to an 8-fold increased risk of AD among Bangladeshis.

Microglia play a critical role in synapse remodeling and neuroinflammation, both of which are dysregulated in Alzheimer’s disease (AD). However, most in vitro models rely on neonatal or immortalized microglia, limiting their relevance to adult pathophysiological context. Here, we present a compartmentalized microfluidic co-culture platform that enables spatially controlled interactions between primary cortical neurons and adult microglia from wild-type (WT) and APP-transgenic mice. This system allows precise functional analysis of microglia–synapse interactions under defined inflammatory conditions. Upon lipopolysaccharide (LPS) stimulation, APP microglia exhibited exaggerated morphological responses, elevated IL-1β secretion, and selectively increased uptake of synaptic material. In contrast, internalization of non-specific substrates such as pHrodo™ Zymosan remained unchanged, suggesting substrate-specific microglial responses. Blocking the complement receptor CD11b abolished the LPS-induced increase in synaptic uptake, confirming the role of complement-dependent pathways. Transcriptomic profiling revealed robust inflammatory responses in both genotypes, with genotype-dependent differences in proinflammatory gene expression, consistent with a primed immune phenotype. Importantly, increased synaptic uptake occurred without measurable loss of global synaptic connectivity, highlighting the ability of the system to detect microglial functional changes. This model captures genotype-dependent microglial reactivity under inflammatory stimulus and provides a physiologically relevant, tractable in vitro platform for dissecting microglial contributions to synaptic vulnerability under inflammatory conditions relevant to neurodegenerative diseases.

Abstract Purpose: To assess the potential of an estrogen receptor beta (ERβ) agonist as an immunotherapy for triple negative breast cancer (TNBC). Background: Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer characterized by the absence of ERα, PR, and HER2 expression with limited treatment options. Although immune checkpoint inhibitors (ICIs) have shown some benefit, response rates remain low in advanced-stage TNBC. This highlights a critical gap in our understanding of oncogenic mechanisms, especially those leading to immunosuppressive tumor microenvironment (TME), and underscores the urgent need for innovative therapeutic targets to improve patient outcomes. Estrogen receptor beta (ERβ), expressed in approximately 30% of TNBCs, is a subtype of estrogen receptor with known anti-tumor properties. While prior studies have established ERβ’s tumor-suppressive role, its effect on the TME remains poorly defined. Despite recently observed clinical associations of ERβ with improved prognosis and immune-related markers, the mechanisms by which ERβ impacts immune cell recruitment, phenotype, and response to immunotherapy have not been thoroughly studied. Here, we aim to define how ERβ regulates immune activity in TNBC and to evaluate its utility as an immunotherapeutic target and biomarker. Methods: To test whether tumor-specific ERβ activity contributes to an immunostimulatory tumor microenvironment, we generated unique syngeneic models and patient-derived xenografts (PDXs) of TNBC with altered ERβ expression and investigated differences in tumor growth and immunophenotype using flow cytometry and immunohistochemistry. Single-cell and spatial genomics were used to study how ERβ alters signaling in tumor cells, affecting effector cells to reduce immunosuppression. To determine whether activating ERβ with agonists further stimulates tumor immunity and inhibits tumor progression, we administered the ERβ agonist LY500307, which is clinically tested in other diseases. ERβ targets and downstream signaling were validated through transcriptional and functional studies in isolated immune cells and cocultures. Lastly, we correlated ERβ’s expression and function with immune signatures and clinical outcome by deconvoluting sequencing data from TCGA-profiled breast cancers and through spatial proteomics analysis of a tissue microarray with TNBC samples. Result: We observed that activated tumor-specific ERβ leads to slowed tumor growth and a less immunosuppressive TME, which is characterized by a significant reduction in tumor-associated M2-like macrophages and increased cytotoxic T cell activity. RNA-seq and cytokine profiling of LY500307-treated ERβ-expressing breast cancer cells identified key target cytokines as downstream mediators, particularly CXCL2, CCL5, CSF2, and IL4 that regulate macrophage function and antigen presentation during tumor adaptive immunity. Preliminary clinical analysis revealed an inverse correlation between ERβ expression and the frequency of myeloid cells that predicted a worse patient outcome, reinforcing the prognostic significance of the receptor. Conclusions: By integrating spatial and single-cell genomics, and immune-functional assays, this study uncovers important functional and mechanistic features of the immunomodulatory role of ERβ. Our findings aim to transform our understanding of ERβ as a tumor suppressor in the immunosuppressive TME of TNBC and could help identify predictive biomarkers and therapy targets to improve patient outcomes. Citation Format: K. A. Zambo, F. Nikolos, H. Nagandla, K. Cap, A. Phillips, W. Qian, J. Qian, K. Chan, J. Chang, C. Thomas. Targeting ERβ signaling as a novel immunotherapeutic strategy in TNBC [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS3-12-03.