Increased Macrophage Recruitment Research Articles

T cell specific deletion of Casitas B lineage lymphoma-b reduces atherosclerosis, but increases plaque T cell infiltration and systemic T cell activation.

Atherosclerosis is a lipid-driven inflammatory disease of the arterial wall, and the underlying cause of the majority of cardiovascular diseases. Recent advances in high-parametric immunophenotyping of immune cells indicate that T cells constitute the major leukocyte population in the atherosclerotic plaque. The E3 ubiquitin ligase Casitas B-lymphoma proto-oncogene-B (CBL-B) is a critical intracellular regulator that sets the threshold for T cell activation, making CBL-B a potential therapeutic target to modulate inflammation in atherosclerosis. We previously demonstrated that complete knock-out of CBL-B aggravated atherosclerosis in Apoe-/- mice, which was attributed to increased macrophage recruitment and increased CD8+ T cell activation in the plaque. To further study the T cell specific role of CBL-B in atherosclerosis, Apoe-/- CD4cre Cblb fl/fl (Cbl-bcKO) mice and Apoe-/-CD4WTCblbfl/fl littermates (Cbl-bfl/fl) were fed a high cholesterol diet for ten weeks. Cbl-bcKO mice had smaller atherosclerotic lesions in the aortic arch and root compared to Cbl-bfl/fl, and a substantial increase in CD3+ T cells in the plaque. Collagen content in the plaque was decreased, while other plaque characteristics including plaque necrotic core, macrophage content, and smooth muscle cell content, remained unchanged. Mice lacking T cell CBL-B had a 1.4-fold increase in CD8+ T cells and a 1.8-fold increase in regulatory T cells in the spleen. Splenic CD4+ and CD8+ T cells had increased expression of C-X-C Motif Chemokine Receptor 3 (CXCR3) and interferon-γ (IFN-γ), indicating a T helper 1 (Th1)-like/effector CD8+ T cell-like phenotype. In conclusion, Cbl-bcKO mice have reduced atherosclerosis but show increased T cell accumulation in the plaque accompanied by systemic T cell activation.

Interaction between Macrophages and Adipose Stromal Cells Increases the Angiogenic and Proliferative Potential of Pregnancy-Associated Breast Cancers.

Pregnancy associated breast cancers (PABCs) exhibit increased aggressiveness and overall poorer survival. During lactation, changes take place in the breast tissue microenvironment that lead to increased macrophage recruitment and alterations in adipose stromal cells (ASC-Ls). The interaction of these cells in PABCs could play a role in the increased aggressiveness of these cancers. We utilized an in vitro co-culture model to recreate the interactions of ASC-Ls and macrophages in vivo. We performed qRT-PCR to observe changes in gene expression and cytokine arrays to identify transcriptional changes that result in an altered microenvironment. Additionally, functional assays were performed to further elicit how these changes affect tumorigenesis. The co-culture of ASC-Ls and macrophages altered both mRNA expression and cytokine secretion in a tumor promoting manner. Tumorigenic cytokines, such as IL-6, CXCL1, CXCL5, and MMP-9 secretion levels, were enhanced in the co-culture. Additionally, conditioned media from the co-culture elevated the tumor cell proliferation and angiogenic potential of endothelial cells. These finds indicate that the changes seen in the microenvironment of PABC, specifically the secretion of cytokines, play a role in the increased tumorigenesis of PABCs by altering the microenvironment to become more favorable to tumor progression.

Abstract #1407860: Rare Cause of Non-PTH Mediated Hypercalcemia Due to Pneumocystis Pneumonia in Renal Transplant Recipient

Hypercalcemia secondary to persistent hyperparathyroidism is common in kidney transplant recipients (KTR). We report a rare cause of non-PTH mediated hypercalcemia in KTR due to pneumocystis jirovecii pneumonia (PJP). The incidence of PJP in KTR is 5-15% in absence of antibiotic prophylaxis. Incidence of hypercalcemia in KTR with PJP is unclear, but scattered case reports are found in literature. The proposed mechanism for hypercalcemia is an infectious granulomatous reaction. PJP induced hypercalcemia needs to be considered in KTR patients with non-PTH mediated hypercalcemia. A 62-year-old male with kidney transplant for renal failure from glomerulosclerosis, three years prior to presentation was admitted for dyspnea and fever. Imaging showed bilateral lung infiltrates, concerning for multifocal infection. Considering his imaging findings and elevated Beta D glucan levels, he was empirically started on PJP treatment with atovaquone on day 4 of admission. Bactrim was not used due to acute renal failure. On day 1, calcium was 10 mg/dL (8.4-10.4), which then progressively increased from 10.7mg/dl on day 4 to a peak calcium level of 14.4 mg/dL on day 12. Further work up showed PTH: 4.7 pg/mL (12-88), PTHrP: 0.6 pMol/L (< /= 4.2), Vitamin D 1, 25: 198 pg/mL (18-72), Vitamin D 25: 79 ng/mL (20-100), SPEP: no M spike, UPEP: no M spike but had a lysozyme band suggestive of granulomatous infection, other fungal studies negative, normal thyroid levels, AFB culture negative. On day 12, he was started on prednisone 60mg presuming hypercalcemia from PJP. On day 13, calcium improved to 11.7 mg/ dL, but his renal function worsened requiring hemodialysis (HD). On day 14, he had respiratory failure requiring intubation and underwent bronchio-alveolar lavage (BAL) which was positive for pneumocystis PCR. He was started on bactrim on day 17 and continued on high dose steroid. By day 19, he was extubated, renal function stabilized without HD and calcium normalized to 8.9 mg/dL. Unfortunately, he had gastrointestinal bleed and refused further procedures eventually opting for hospice on day 23. PJP is a common opportunistic infection in immunosuppressed patients like KTR. The advent of prophylaxis has significantly decreased the incidence of PJP in KTR to 0.3%-2.6%. PJP in KTR is sometimes associated with hypercalcemia. Prevalence of hypercalcemia in KTR with PJP is unclear, but as per a hospital based retrospective study (Hamroun et al., 2019), 37% of PJP patients in KTR (18/49) had hypercalcemia that preceded pneumonia/findings on imaging. The proposed mechanism for hypercalcemia is granulomatous in nature, due to increased extra renal production of 1 alpha hydroxylase enzyme from increased macrophage recruitment in lungs to clear pneumocystis organisms. Hypercalcemia resolved after completion of treatment and resolution of PJP. High dose steroids can be used as hypercalcemia is mediated by a granulomatous reaction. It is crucial for physicians to have a high index of suspicion for PJP as the etiology of pneumonia in immunocompromised organ transplant recipients with non- PTH mediated hypercalcemia, thus ensuring timely diagnosis and treatment.

Inhibition of autophagy in macrophage promotes IL-1β-mediated hepatocellular carcinoma progression via inflammasome accumulation and self-recruitment

Hepatocellular carcinoma (HCC) has a complex and changeable tumor microenvironment. Despite emerging evidence focusing on autophagy process within immune cells, the function and regulatory mechanism of macrophage autophagy in tumor progression remains unclear. Our results of multiplex-immunohistochemistry and RNA-sequencing identified the reduced levels of autophagy in tumor macrophages in the HCC microenvironment, associated with a poor prognosis and increased microvascular metastasis in HCC patients. Specifically, HCC suppressed the macrophage autophagy initiation through the up-regulation of mTOR and ULK1 phosphorylation at Ser757. Knockdown of autophagy-related proteins to further inhibit autophagy significantly boosted the metastatic potential of HCC. Mechanistically, the accumulation of NLRP3 inflammasome mediated by autophagy inhibition promoted the cleavage, maturation, and release of IL-1β, which facilitated the HCC progression, eventually accelerating HCC metastasis via the epithelial-mesenchymal transition. Autophagy inhibition provoked macrophage self-recruitment through the CCL20-CCR6 signaling was also a crucial account of HCC progression. Recruited macrophages mediated the cascade amplification of IL-1β and CCL20 to form a novel pro-metastatic positive feedback loop through promoting HCC metastasis and increased macrophage recruitment, respectively. Notably, targeting IL-1β/IL-1 receptor signaling impaired lung metastasis induced by macrophage autophagy inhibition in a mice HCC lung metastasis model. In summary, this study highlighted that inhibition of tumor macrophage autophagy facilitated HCC progression by increasing IL-1β secretion via NLRP3 inflammasome accumulation and by macrophage self-recruitment through the CCL20 signaling pathway. Interruption of this metastasis-promoting loop by IL-1β blockade may provide a promising therapeutic strategy for HCC patients.

Podocyte derived TNF-α mediates monocyte differentiation and contributes to glomerular injury.

Diabetes shortens the life expectancy by more than a decade, and the excess mortality in diabetes is correlated with the incidence of kidney disease. Diabetic kidney disease (DKD) is the leading cause of end-stage kidney disease. Macrophage accumulation predicts the severity of kidney injury in human biopsies and experimental models of DKD. However, the mechanism underlying macrophage recruitment in diabetes glomeruli is unclear. Elevated plasma growth hormone (GH) levels in type I diabetes and acromegalic individuals impaired glomerular biology. In this study, we examined whether GH-stimulated podocytes contribute to macrophage accumulation. RNA-seq analysis revealed elevated TNF-α signaling in GH-treated human podocytes. Conditioned media from GH-treated podocytes (GH-CM) induced differentiation of monocytes to macrophages. On the other hand, neutralization of GH-CM with the TNF-α antibody diminished GH-CM's action on monocytes. The treatment of mice with GH resulted in increased macrophage recruitment, podocyte injury, and proteinuria. Furthermore, we noticed the activation of TNF-α signaling, macrophage accumulation, and fibrosis in DKD patients' kidney biopsies. Our findings suggest that podocytes could secrete TNF-α and contribute to macrophage migration, resulting in DKD-related renal inflammation. Inhibition of either GH action or TNF-α expression in podocytes could be a novel therapeutic approach for DKD treatment.

EMILIN-1 deficiency promotes chronic inflammatory disease through TGFβ signaling alteration and impairment of the gC1q/α4β1 integrin interaction

Alterations in extracellular matrix (ECM) components that modulate inflammatory cell behavior have been shown to serve as early starters for multifactorial diseases such as fibrosis and cancer. Here, we demonstrated that loss of the ECM glycoprotein EMILIN-1 alters the inflammatory context in skin during IMQ-induced psoriasis, a disease characterized by a prominent inflammatory infiltrate and alteration of vessels that appear dilated and tortuous. Abrogation of EMILIN-1 expression or expression of the EMILIN-1 mutant E933A impairs macrophage polarization and leads to imbalanced tissue homeostasis. We found that EMILIN-1 deficiency is associated with dilated lymphatic vessels, increased macrophage recruitment and psoriasis severity. Importantly, the null or mutant EMILIN-1 background was characterized by the induction of a myofibroblast phenotype, which in turn drove macrophages towards the M1 phenotype. By using the transgenic mouse model carrying the E933A mutation in the gC1q domain of EMILIN-1, which abolishes the interaction with α4- and α9-integrins, we demonstrated that the observed changes in TGFβ signaling were due to both the EMI and gC1q domains of EMILIN-1. gC1q may exert multiple functions in psoriasis, in the context of a final, more consistent inflammatory condition by controlling skin homeostasis via interaction with both keratinocytes and fibroblasts, influencing non-canonical TGFβ signaling, and likely acting on lymphatic vessel structure and function. The analyses of human psoriatic lesions, in which lower levels of EMILIN-1 were present with a very rare association with lymphatic vessels, support the multifaceted role of this ECM component in the skin inflammatory scenario.

Sulfatase-2 from Cancer Associated Fibroblasts: An Environmental Target for Hepatocellular Carcinoma?

Introduction: Heparin sulphate proteoglycans in the liver tumour microenvironment (TME) are key regulators of cell signalling, modulated by sulfatase-2 (SULF2). SULF2 overexpression occurs in hepatocellular carcinoma (HCC). Our aims were to define the nature and impact of SULF2 in the HCC TME. Methods: In liver biopsies from 60 patients with HCC, expression and localization of SULF2 were analysed associated with clinical parameters and outcome. Functional and mechanistic impacts were assessed with immunohistochemistry (IHC), in silico using The Cancer Genome Atlas (TGCA), in primary isolated cancer activated fibroblasts, in monocultures, in 3D spheroids, and in an independent cohort of 20 patients referred for sorafenib. IHC targets included αSMA, glypican-3, β-catenin, RelA-P-ser536, CD4, CD8, CD66b, CD45, CD68, and CD163. SULF2 impact of peripheral blood mononuclear cells was assessed by migration assays, with characterization of immune cell phenotype using fluorescent activated cell sorting. Results: We report that while SULF2 was expressed in tumour cells in 15% (9/60) of cases, associated with advanced tumour stage and type 2 diabetes, SULF2 was more commonly expressed in cancer-associated fibroblasts (CAFs) (52%) and independently associated with shorter survival (7.2 vs. 29.2 months, p = 0.003). Stromal SULF2 modulated glypican-3/β-catenin signalling in vitro, although in vivo associations suggested additional mechanisms underlying the CAF-SULF2 impact on prognosis. Stromal SULF2 was released by CAFS isolated from human HCC. It was induced by TGFβ1, promoted HCC proliferation and sorafenib resistance, with CAF-SULF2 linked to TGFβ1 and immune exhaustion in TGCA HCC patients. Autocrine activation of PDGFRβ/STAT3 signalling was evident in stromal cells, with the release of the potent monocyte/macrophage chemoattractant CCL2 in vitro. In human PBMCs, SULF2 preferentially induced the migration of macrophage precursors (monocytes), inducing a phenotypic change consistent with immune exhaustion. In human HCC tissues, CAF-SULF2 was associated with increased macrophage recruitment, with tumouroid studies showing stromal-derived SULF2-induced paracrine activation of the IKKβ/NF-κB pathway, tumour cell proliferation, invasion, and sorafenib resistance. Conclusion: SULF2 derived from CAFs modulates glypican-3/β-catenin signalling but also the HCC immune TME, associated with tumour progression and therapy resistance via activation of the TAK1/IKKβ/NF-κB pathway. It is an attractive target for combination therapies for patients with HCC.

Cholesterol absorption blocker ezetimibe prevents muscle wasting in severe dysferlin-deficient and mdx mice.

BackgroundMuscular dystrophy (MD) causes muscle wasting and is often lethal in patients due to a lack of proven therapies. In contrast, mouse models of MD are notoriously mild. We have previously shown severe human‐like muscle pathology in mdx [Duchenne MD (DMD)] and dysferlin‐deficient limb‐girdle MD type 2B (LGMD2B) mice by inactivating the gene encoding for apolipoprotein E (ApoE), a lipid transporter synthesized by the liver, brain and adipocytes to regulate lipid and fat metabolism. Having recently established that human DMD is a novel type of primary genetic dyslipidaemia with elevated cholesterol, we sought to determine whether cholesterol could exacerbate the muscle wasting process observed in severe rodent MD.MethodsSevere mdx and dysferlin knock‐out mice lacking ApoE were treated with ezetimibe (15 mg/kg/day), a clinically approved drug exhibiting few pleiotropic effects. In separate studies, dietary cholesterol was raised (from 0.2% to 2% cholesterol) in combination with experimental micro‐injury and direct cholesterol injection assays. Muscles were assessed histologically for changes in collagen and adipocyte infiltration and both transcriptomic and cellular changes by RNA‐seq and fluorescence‐activated cell sorting analysis.ResultsTreatment of severe DMD and LGMD2B mice with ezetimibe completely prevented clinical signs of ambulatory dysfunction (0% incidence vs. 33% for vehicle treatment; P < 0.05). Histological analyses revealed that ezetimibe‐reduced fibro‐fatty infiltration up to 84% and 63% in severely affected triceps (P ≤ 0.0001) and gastrocnemius (P ≤ 0.003) muscles, resulting in a respective 1.9‐fold and 2.2‐fold retention of healthy myofibre area (P ≤ 0.0001). Additionally, raising dietary cholesterol and thus concentrations of plasma low‐density lipoprotein‐associated cholesterol (by 250%; P < 0.0001) reduced overall survivability (by 100%; P < 0.001) and worsened muscle damage in the LGMD2B triceps by 767% (P < 0.03). Micro‐pin‐induced mechanical injury in LGMD2B mice fed a high cholesterol diet exacerbated muscle damage by 425% (P < 0.03) and increased macrophage recruitment (by 98%; P = 0.03) compared with those injured on a chow diet. Parallel RNA‐seq analyses revealed that injury in cholesterol‐fed mice also modulated the expression of 3671 transcripts (1953 up‐regulated), with fibrogenic, inflammatory and programmed cell death‐associated pathways among the most enriched. Mice lacking dysferlin also displayed heightened muscle necrosis (by 123%; P < 0.0001) following a direct intramuscular injection of cholesterol compared with control mice.ConclusionsCholesterol exacerbates rodent MD. Specific inhibition of cholesterol absorption with ezetimibe may safely attenuate human MD severity and delay death.

Ablation of mpeg+ Macrophages Exacerbates mfrp-Related Hyperopia.

PurposeProper refractive development of the eye, termed emmetropization, is critical for focused vision and is impacted by both genetic determinants and several visual environment factors. Improper emmetropization caused by genetic variants can lead to congenital hyperopia, which is characterized by small eyes and relatively short ocular axial length. To date, variants in only four genes have been firmly associated with human hyperopia, one of which is MFRP. Zebrafish mfrp mutants also have hyperopia and, similar to reports in mice, exhibit increased macrophage recruitment to the retina. The goal of this research was to examine the effects of macrophage ablation on emmetropization and mfrp-related hyperopia.MethodsWe utilized a chemically inducible, cell-specific ablation system to deplete macrophages in both wild-type and mfrp mutant zebrafish. Spectral-domain optical coherence tomography was then used to measure components of the eye and determine relative refractive state. Histology, immunohistochemistry, and transmission electron microscopy were used to further study the eyes.ResultsAlthough macrophage ablation does not cause significant changes to the relative refractive state of wild-type zebrafish, macrophage ablation in mfrp mutants significantly exacerbates their hyperopic phenotype, resulting in a relative refractive error 1.3 times higher than that of non-ablated mfrp siblings.ConclusionsGenetic inactivation of mfrp leads to hyperopia, as well as abnormal accumulation of macrophages in the retina. Ablation of the mpeg1-positive macrophage population exacerbates the hyperopia, suggesting that macrophages may be recruited in an effort help preserve emmetropization and ameliorate hyperopia.

The IL-23/IL-17 axis promotes the formation of retinal neovascularization by activating the NLRP3 inflammasome in macrophages in an experimental retinopathy mouse model.

Retinal neovascularization (RNV), a pathological process shared among diabetic retinopathy, retinopathy of prematurity and other retinopathies, has been widely studied, but the mechanism remains unclear. In this study, the mechanism by which the interleukin (IL)-23/IL-17 axis regulates RNV in oxygen-induced retinopathy (OIR) model mice and in cell experiments in vitro was characterized. In the retinas of OIR mice, IL-23/IL-17 axis activation was increased and regulated RNV formation, and this effect was accompanied by increased macrophage recruitment and nucleotide-binding domain leucine-rich repeat and pyrin domain containing receptor 3 (NLRP3) inflammasome activation. Moreover, inhibiting the IL-23/IL-17 axis reduced the number of macrophage and the expression and activation of NLRP3 inflammasome. On the other hand, recombinant (r) IL-23p19 and rIL-17A promoted the expression and activation of NLRP3 inflammasome, and the proliferation and migration of macrophages. Furthermore, macrophage elimination decreased the activation of IL-23/IL-17 axis and the expression and activation of NLRP3 inflammasome. In summary, our experiments showed that the IL-23/IL-17 axis promoted the formation of RNV by activating the NLRP3 inflammasome in retinal macrophages of an OIR mouse model.

USP12 downregulation orchestrates a protumourigenic microenvironment and enhances lung tumour resistance to PD-1 blockade

Oncogenic activation of KRAS and its surrogates is essential for tumour cell proliferation and survival, as well as for the development of protumourigenic microenvironments. Here, we show that the deubiquitinase USP12 is commonly downregulated in the KrasG12D-driven mouse lung tumour and human non-small cell lung cancer owing to the activation of AKT-mTOR signalling. Downregulation of USP12 promotes lung tumour growth and fosters an immunosuppressive microenvironment with increased macrophage recruitment, hypervascularization, and reduced T cell activation. Mechanistically, USP12 downregulation creates a tumour-promoting secretome resulting from insufficient PPM1B deubiquitination that causes NF-κB hyperactivation in tumour cells. Furthermore, USP12 inhibition desensitizes mouse lung tumour cells to anti-PD-1 immunotherapy. Thus, our findings propose a critical component downstream of the oncogenic signalling pathways in the modulation of tumour-immune cell interactions and tumour response to immune checkpoint blockade therapy.

Exercise‐linked FNDC5/Irisin attenuates macrophage‐mediated renal inflammation in type 1 diabetes in aged mice

Diabetes is associated with chronic low-grade inflammation in the kidney. Both classically and alternately activated macrophages play key roles in diabetic nephropathy by mediating inflammatory processes and anti-inflammatory responses respectively. Physical activity is known to modulate innate immune function, indeed exercise training is reported to reduce low-grade inflammation and improve insulin sensitivity in obese subjects. FNDC5 is a myokine secreted by skeletal muscles during exercise and the cleavage of its extracellular domain yields Irisin. In vitro studies have demonstrated that Irisin exhibits anti-inflammatory properties in adipose tissues and RAW 264.7 cells. The purpose of our study was to investigate the effect of exercise induced FNDC5/Irisin on inflammation and damage of aged kidney in type I diabetes. C57BL/6-Ins2Akita/J (Type 1 diabetes, Akita) and C57BL/6J (Wild type, WT) mice aged 54 - 56 weeks underwent 16-week exercise training of 280 m run on treadmill at speed of 7m/min. for 5 days/week for 2 weeks and increased to 12 m/min. for the remaining 14 weeks. FNDC5/Irisin was upregulated in the kidneys of WT and Akita exercise groups but to a greater magnitude in the WT. Sedentary Akita mice kidneys showed increased macrophage recruitment and M1 macrophages (CCL2, CXCL2, and CD86+/CD40+ cells) and inflammatory cytokine production. In contrast, Akita mice undergoing exercise training increased anti-inflammatory profile and M2 phenotype polarization (CD206+ cells). Exercise induced changes were associated with robust activation of AMPK and MAPK signaling in Akita mice. In comparison to sedentary group, exercise training reduced renal resistive index, improved cortical blood flow and glomerular filtration rate in WT and Akita mice. Taken together, our results suggest that exercise training and Irisin secretion protects the aged kidney from type 1 diabetes induced damage by reducing macrophage-mediated inflammation.

Alveolar epithelial TET2 is not involved in the development of bleomycin-induced pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease of unknown etiology with minimal treatment options. Repetitive alveolar epithelial injury has been suggested as one of the causative mechanisms of this disease. Type 2 alveolar epithelial cells (AEC2) play a crucial role during fibrosis by functioning as stem cells able to repair epithelial damage. The DNA demethylase Tet methylcytosine dioxygenase 2 (TET2) regulates the stemness of multiple types of stem cells, but whether it also affects the stemness of AEC2 during fibrosis remains elusive. To study the role of TET2 in AEC2 during fibrosis, we first determined TET2 protein levels in the lungs of IPF patients and compared TET2 expression in AEC2 of IPF patients and controls using publicly available data sets. Subsequently, pulmonary fibrosis was induced by the intranasal administration of bleomycin to wild-type and AEC2-specific TET2 knockout mice to determine the role of TET2 in vivo. Fibrosis was assessed by hydroxyproline analysis and fibrotic gene expression. Additionally, macrophage recruitment and activation, and epithelial injury were analyzed. TET2 protein levels and gene expression were downregulated in IPF lungs and AEC2, respectively. Bleomycin inoculation induced a robust fibrotic response as indicated by increased hydroxyproline levels and increased expression of pro-fibrotic genes. Additionally, increased macrophage recruitment and both M1 and M2 activation were observed. None of these parameters were, however, affected by AEC2-specific TET2 deficiency. TET2 expression is reduced in IPF, but the absence of TET2 in AEC2 cells does not affect the development of bleomycin-induced pulmonary fibrosis.

TNF\u03b1 secreted by glioma associated macrophages promotes endothelial activation and resistance against anti-angiogenic therapy

One of the most prominent features of glioblastoma (GBM) is hyper-vascularization. Bone marrow-derived macrophages are actively recruited to the tumor and referred to as glioma-associated macrophages (GAMs) which are thought to provide a critical role in tumor neo-vascularization. However, the mechanisms by which GAMs regulate endothelial cells (ECs) in the process of tumor vascularization and response to anti-angiogenic therapy (AATx) is not well-understood. Here we show that GBM cells secrete IL-8 and CCL2 which stimulate GAMs to produce TNFα. Subsequently, TNFα induces a distinct gene expression signature of activated ECs including VCAM-1, ICAM-1, CXCL5, and CXCL10. Inhibition of TNFα blocks GAM-induced EC activation both in vitro and in vivo and improve survival in mouse glioma models. Importantly we show that high TNFα expression predicts worse response to Bevacizumab in GBM patients. We further demonstrated in mouse model that treatment with B20.4.1.1, the mouse analog of Bevacizumab, increased macrophage recruitment to the tumor area and correlated with upregulated TNFα expression in GAMs and increased EC activation, which may be responsible for the failure of AATx in GBMs. These results suggest TNFα is a novel therapeutic that may reverse resistance to AATx. Future clinical studies should be aimed at inhibiting TNFα as a concurrent therapy in GBMs.

Abstract PO042: Microfluidic modeling of tumor-macrophage signaling in ovarian cancer

Abstract In ovarian cancer, the presence of macrophages in the tumor microenvironment (TME) has been associated with poor clinical outcomes. Understanding mechanisms of macrophage recruitment and signaling with tumor cells in the TME may uncover novel therapeutic targets to block the pro-tumor effects of macrophages and improve patient outcomes. Several tumor secreted factors, such as mCSF, CCL2, IL8, and periostin have been implicated in the recruitment of macrophages to the tumor site. However, previous studies of macrophage recruitment have utilized culture systems that fail to recapitulate TME complexity. Therefore, a 3D physiologically relevant microfluidic platform was used in this work that can accurately control cell-cell interactions. Our microfluidic design incorporates chemokine concentration gradients and allows for the study of the spatiotemporal macrophage infiltration dynamics towards ovarian cancer cells using live cell microscopy. We first studied the abilities of a panel of high grade serous ovarian cancer models comprised of established cancer cell lines (murine ID8 and human CaOV3, OHSAHO, OVCAR8) and patient-derived high-grade serous ovarian cancer xenografts (4 PDX models) to recruit macrophages via microfluidic and collagen-droplet based 3D assays. The presence of tumor cells enhanced macrophage infiltration into collagen 3-fold after 48 hours. We found that ovarian cancer models that efficiently recruited macrophages expressed higher levels of mCSF, CCL2, and IL8 cytokines. Furthermore, tumor cell secreted factors more potently increased macrophage recruitment compared to chemotactic gradients of CCL2 and mCSF, indicating a complex signaling network between tumor cells and macrophages. RAW264.7 murine macrophages additionally induced resistance to cisplatin-induced cell death in ID8 cells proportional to increasing macrophage:tumor cell ratios. We also studied the ability of CSF1R inhibition to block macrophage infiltration. Treatment with BLZ945, a potent CSF1R inhibitor that is evaluated in clinical trials, effectively blocked the recruitment of the RAW264.7 macrophages towards ID8 ovarian cancer cells. We subsequently characterized the attachment and invasion profiles of the human and murine ovarian cancer models in syngeneic and immunocompromised xenografts in vivo. We found that tumor cells attached and invaded the ovaries, abdominal organs, and fatty tissue. In a preliminary analysis, one of the PDX models that efficiently recruited macrophages also formed invasive implants, while another PDX model with poor macrophage infiltration did not exhibit invasive implant formation. This work demonstrates the capability of a microfluidic platform to model macrophage infiltration in ovarian cancer. In ongoing studies using this microfluidic platform we are investigating the effects of chemotherapy-induced changes in the tumor cell secretome on macrophage infiltration and the resulting effects on tumor cell chemotherapy sensitivity. Citation Format: Alexis L. Scott, Oluwadamilola Ayoola, Ioannis K. Zervantonakis. Microfluidic modeling of tumor-macrophage signaling in ovarian cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on the Evolving Tumor Microenvironment in Cancer Progression: Mechanisms and Emerging Therapeutic Opportunities; in association with the Tumor Microenvironment (TME) Working Group; 2021 Jan 11-12. Philadelphia (PA): AACR; Cancer Res 2021;81(5 Suppl):Abstract nr PO042.

OTUD5-mediated deubiquitination of YAP in macrophage promotes M2 phenotype polarization and favors triple-negative breast cancer progression.

Macrophages, which are highly plastic, can be polarized to M1 or M2 subtypes according to the diverse signals in complex microenvironment. Studies have shown the activation of YAP, an oncogenic transcriptional co-activator, increased macrophage recruitment. However, its role in macrophage polarization remains to be elucidated, especially in triple-negative breast cancer (TNBC) progression. Here we found TNBC cells increased YAP expression in macrophages, which depended on OTUD5-mediated deubiquitination and stabilization of YAP, then the high expression of YAP polarized macrophage to the M2-like phenotype. Moreover, the elevation of YAP in M2-like macrophage promotes the pro-metastatic potential of TNBC cells via MCP-1/CCR2 pathway. We also observed high expression of YAP in M2 macrophage was negatively related to survival. Collectively, our finding suggested the therapeutic strategy that targets YAP+ M2 macrophage could be a novel option for TNBC treatment.

Abstract 13040: Left Ventricle Dysfunction is Prevented by the Treatment With Methotrexate Carried in Lipid Nanoparticles in Lipopolysaccharide-injected Rats

Introduction: In infectious processes, left ventricle (LV) dysfunction is often associated with dysregulation of the immune response. LDE, a lipid core nanoparticle resembling LDL, is able to concentrate in inflammatory sites. We showed that methotrexate (MTX), associated with LDE, modulated inflammation and improved cardiac function in rats with myocardial infarction Hypothesis: Investigate therapeutic effects of LDE-MTX on LV function in lipopolysaccharide (LPS)-injected rats Methods: Wistar rats were submitted to 2 injections of LPS (10mg/kg ip), with 24h interval. Animals were allocated to control group (CT, without LPS) and 3 LPS groups: LDE, treated with only LDE; MTX, with commercial MTX; and LDE-MTX. LDE-MTX dose was 1mg/kg I.P. 72h after LPS, animals were submitted to echocardiographic analysis. Animals were euthanised for analysis of the LV Results: Rats treated with LDE developed diastolic dysfunction and presented decreased diastolic volume and diameter of the LV, which was prevented by LDE-MTX. Only LDE-MTX treatment elicited cardiac hypertrophy through the increase of the thickness of LV septum and posterior wall, LV mass, relative heart weight and myocyte diameter. Inflammatory and apoptotic markers were similar in LPS groups, but LDE-MTX treatment increased macrophage recruitment (CD68). Angiogenesis, represented by vascular endothelial growth factor (VEGF), was higher in LDE-MTX compared to all other groups. Hypoxia-inducible factor 1 alpha, which was remarkably higher in LDE, was normalized by LDE-MTX to CT levels. A1, A2b and A3 adenosine receptors expression was higher in LDE-MTX, compared to CT, indicating an increase in intracellular adenosine. Myocyte diameter was positively correlated with VEGF (r2= 0.52; p&lt;0.0001) Conclusions: The increased recruitment of immune cells to the LV indicates that treatment with LDE-MTX was effective in activating immune response, impaired by LPS. LDE-MTX increased intracellular adenosine availability, contributing to an adaptive LV hypertrophy, increase in angiogenesis and diminished cellular hypoxia. These mechanisms conceivably elicited the observed LV improvement of diastolic dysfunction caused by LPS challenge

TAMI-46. TNFα SECRETED BY GLIOMA ASSOCIATED MACROPHAGES PROMOTES ENDOTHELIAL ACTIVATION AND RESISTANCE AGAINST ANTI-ANGIOGENIC THERAPY

Abstract Glioblastoma (GBM) remains a universal fatal disease and improving survival remains a challenge. One of the most prominent features of GBM is hyper-vascularization, characterized by abnormally dilated, distorted, and leaky vessels. Bone marrow (BM)-derived macrophages are recognized to be an important host cell population that are actively recruited to the tumor and referred to as glioma-associated macrophages (GAMs). GAMs are found to associate closely with blood vessels, and thought to provide a critical role in tumor neo-vascularization. However, the mechanisms by which GAMs regulate and promote endothelial cells (ECs) in the process of tumor vascularization and response to anti-angiogenic therapy (AATx) is not understood. To understand how GBM, GAMs and EC interacts, we designed and developed a novel GBMs-GAMs-EC co-culture system as well as a unique in vivo model in which the BM of NOD/SCID mice were reconstituted with red fluorescent protein (RFP)-BM cells to create a chimeric mouse and then using intracranial injection of GFP-U87 cells to create a GBM xenograft. Our study is the first to demonstrate that glioma cells-secreted IL8 and CCL2 which stimulate GAMs to secrete TNFα and promote EC activation. TNFα inhibition led to normalization of the tumor vasculature and significant improvement in survival in glioma mice model. More importantly, we validate these findings using clinical data showing that TNFα is a predictor of overall survival and response to AATx in GBM patients. We further demonstrated that increased macrophage recruitment and upregulation of TNFα in GAMs activating EC in response to bevacizumab treatment is one of the critical molecular mechanisms underlying the failure of AATx in GBM. Collectively, these results provide compelling evidence to further explore the clinical impact of inhibiting TNFα concurrent with AATx.

Macrophages Promote Aortic Valve Cell Calcification and Alter STAT3 Splicing.

Macrophages have been described in calcific aortic valve disease, but it is unclear if they promote or counteract calcification. We aimed to determine how macrophages are involved in calcification using the Notch1+/- model of calcific aortic valve disease. Approach and Results: Macrophages in wild-type and Notch1+/- murine aortic valves were characterized by flow cytometry. Macrophages in Notch1+/- aortic valves had increased expression of MHCII (major histocompatibility complex II). We then used bone marrow transplants to test if differences in Notch1+/- macrophages drive disease. Notch1+/- mice had increased valve thickness, macrophage infiltration, and proinflammatory macrophage maturation regardless of transplanted bone marrow genotype. In vitro approaches confirm that Notch1+/- aortic valve cells promote macrophage invasion as quantified by migration index and proinflammatory phenotypes as quantified by Ly6C and CCR2 positivity independent of macrophage genotype. Finally, we found that macrophage interaction with aortic valve cells promotes osteogenic, but not dystrophic, calcification and decreases abundance of the STAT3β isoform. This study reveals that Notch1+/- aortic valve disease involves increased macrophage recruitment and maturation driven by altered aortic valve cell secretion, and that increased macrophage recruitment promotes osteogenic calcification and alters STAT3 splicing. Further investigation of STAT3 and macrophage-driven inflammation as therapeutic targets in calcific aortic valve disease is warranted.

Topical α-gal nanoparticles accelerate diabetic wound healing.

An inadequate response from macrophages, key orchestrators of the wound healing process, has been implicated in the pathophysiology of impaired healing in diabetes. This study explored the utility of nanoparticles presenting the α-gal (Galα1-3Galβ1-4GlcNAc-R) epitope to induce anti-Gal antibody-mediated local transient recruitment of macrophages to accelerate wound closure and healing in a diabetic murine model. α1,3galactosyltrasferase knockout mice were stimulated to produce anti-Gal antibodies and subsequently diabetes was induced by streptozotocin-induced β-cell destruction. Six mm full-thickness skin wounds were made and α-gal nanoparticles (AGN) were topically applied on postwounding days 0 and 1. Wounds were analysed histologically for macrophage invasion and markers of wound healing, including epithelialization, vascularization and granulation tissue deposition through postoperative day 12. We found that application of AGN transiently but significantly increased macrophage recruitment into the wounds of diabetic mice. Treated wounds demonstrated more rapid closure and enhanced wound healing as demonstrated by significantly accelerated rates of epithelialization, vascularization and granulation tissue deposition. Thus, topical treatment of full-thickness wounds in diabetic mice with α-gal nanoparticles induced a transient but significant increase in macrophage recruitment resulting in an accelerated rate of wound healing. Using α-gal nanoparticles as a topical wound healing adjunct is a simple, safe and effective means of augmenting dysregulated macrophage recruitment present in the diabetic state.