Granulocyte-macrophage Colony-stimulating Factor Receptor Research Articles

Macrophage colony-stimulating factor receptor/CD115+ non-classical monocytes are expanded in systemic lupus erythematosus and associated with lupus nephritis

Objective In systemic lupus erythematosus (SLE), the non-classical monocyte compartment is expanded, but its phenotype and association with clinical disease manifestations have not been explored. Method Monocyte subsets from 39 SLE patients, 32 healthy age-matched controls, and 16 patients from a disease control (autoimmune connective tissue disease other than SLE) were determined based on CD14 and CD16 surface expression. Cell surface expression of the receptors for macrophage colony-stimulating factor (M-CSF) (CD115) and granulocyte–macrophage colony-stimulating factor (GM-CSF) (CD116), as well as 6-Sulpho LacNAc (slan), were analysed by flow cytometry. The association of monocyte populations with disease manifestations, disease activity markers, and current medication of each patient was analysed by chart review. Results Non-classical monocytes displayed a cell-type specific signature of high M-CSF receptor CD115 and low GM-CSF receptor CD116 expression that separated them from the other two monocyte subsets. In healthy individuals, the M-CSF receptor on non-classical monocytes was an age-dependent surface marker, with lower expression in young adults. However, SLE monocytes were characterized by a marked expansion of M-CSF receptor/CD115+ non-classical monocytes in patients of all ages. The expanded population of M-CSF receptor/CD115+ non-classical monocytes was associated with lupus nephritis but not with disease activity, and coexpressed slan. Conclusion The non-classical monocyte subset in SLE is characterized by an expansion of M-CSF receptor/CD115+ cells that are associated with lupus nephritis and coexpress slan.

Recruited atypical Ly6G+ macrophages license alveolar regeneration after lung injury.

The lung is constantly exposed to airborne pathogens and particles that can cause alveolar damage. Hence, appropriate repair responses are essential for gas exchange and life. Here, we deciphered the spatiotemporal trajectory and function of an atypical population of macrophages after lung injury. Post-influenza A virus (IAV) infection, short-lived monocyte-derived Ly6G-expressing macrophages (Ly6G+ Macs) were recruited to the alveoli of lung perilesional areas. Ly6G+ Macs engulfed immune cells, exhibited a high metabolic potential, and clustered with alveolar type 2 epithelial cells (AT2s) in zones of active epithelial regeneration. Ly6G+ Macs were partially dependent on granulocyte-macrophage colony-stimulating factor and interleukin-4 receptor signaling and were essential for AT2-dependent alveolar regeneration. Similar macrophages were recruited in other models of injury and in the airspaces of lungs from patients with suspected pneumonia. This study identifies perilesional alveolar Ly6G+ Macs as a spatially restricted, short-lived macrophage subset promoting epithelial regeneration postinjury, thus representing an attractive therapeutic target for treating lung damage.

Pathogenesis-driven treatment of primary pulmonary alveolar proteinosis.

Pulmonary alveolar proteinosis (PAP) is a syndrome that results from the accumulation of lipoproteinaceous material in the alveolar space. According to the underlying pathogenetic mechanisms, three different forms have been identified, namely primary, secondary and congenital. Primary PAP is caused by disruption of granulocyte-macrophage colony-stimulating factor (GM-CSF) signalling due to the presence of neutralising autoantibodies (autoimmune PAP) or GM-CSF receptor genetic defects (hereditary PAP), which results in dysfunctional alveolar macrophages with reduced phagocytic clearance of particles, cholesterol and surfactant. The serum level of GM-CSF autoantibody is the only disease-specific biomarker of autoimmune PAP, although it does not correlate with disease severity. In PAP patients with normal serum GM-CSF autoantibody levels, elevated serum GM-CSF levels is highly suspicious for hereditary PAP. Several biomarkers have been correlated with disease severity, although they are not specific for PAP. These include lactate dehydrogenase, cytokeratin 19 fragment 21.1, carcinoembryonic antigen, neuron-specific enolase, surfactant proteins, Krebs von Lungen 6, chitinase-3-like protein 1 and monocyte chemotactic proteins. Finally, increased awareness of the disease mechanisms has led to the development of pathogenesis-based treatments, such as GM-CSF augmentation and cholesterol-targeting therapies.

GMCSF: More an Inflammatory Immune ‘Cytokine’ Than a Growth Factor

GMCSF, discovered in 1977, was one of the first growth factors for myelopoiesis. However, over time, it has been found to be redundant for basal myelopoiesis. Rather, its important function seems to be its effect on mature myeloid cells and the immune system. It is produced by a variety of cells, including macrophages, endothelial cells, T-cells etc. and works on the GMCSF receptor, which is mainly expressed by mature myeloid cells such as neutrophils, monocytes and macrophages. It has been found to be an important mediator of at least two autoimmune diseases: rheumatoid arthritis and multiple sclerosis. Animal models prove that GMCSF produced from T-cells play a crucial role in their pathogenesis of both these autoimmune diseases. This has led to the development of therapeutics which target GMCSF or its receptor. Clinical trials have been carried out in rheumatoid arthritis, which have shown modest efficacy. In addition, anti-GMCSF therapy has shown promise in giant cell arteritis.

Mechanism study of tyrosine phosphatase shp-1 in inhibiting hepatocellular carcinoma progression by regulating the SHP2/GM-CSF pathway in TAMs

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. Macrophage-mediated innate immune responses play a crucial role in tumor development. This study revealed the mechanism of SHP-1 in regulating HCC progression. SHP-1 inhibits tumour development in vivo. Increasing SHP-1 expression in macrophages promotes the expression of p-SHP-1, SHP2, and p-SHP-2. In macrophages GM-CSF recruits SHP-2 to the GM-CSF receptor GM-CSFR induces p-SHP-2 dephosphorylation. GM-CSF recruits p-SHP-2 for dephosphorylation by up-regulating HoxA10HOXA10 activates the transcription of TGFβ2 by interacting with tandem cis-elements in the promoter thereby regulating the proliferation and migration of liver cancer cells. GM-CSF inhibits SHP-1 regulation of p-SHP-1, SHP2, and p-SHP-2 in macrophages. Detailed studies have shown that SHP-1 regulates SHP2 expression, and SHP-1 and SHP2 are involved in macrophage M2 polarisation. SHP-1 inhibits HOXA10 and TGFβ2 which in turn regulates the expression of the migration-associated proteins, MMP2/9, and the migration of hepatocellular carcinoma cells. Overexpression of SHP-1 inhibits macrophage M2 polarisation via the p-STAT3/6 signalling pathway Classical markers arginase-1, CD206, CD163 and regulate the expression of M2 polarisation cytokines IL-4 and IL-10. In addition, hypoxia-induced ROS inhibited SHP-1 regulation by suppressing the expression of p-SHP-1. The combined effect of GM-CSF and ROS significantly increased p-HOXA10/TGFβ2 and macrophage M2 polarisation, and the regulatory effect of ROS was significantly suppressed by GM-CSF knockdown. These findings suggest that increasing the expression of tyrosine phosphatase SHP-1 can inhibit hepatocellular carcinoma progression by modulating the SHP2/GM-CSF pathway in TAM and thus inhibit the progression of hepatocellular carcinoma.

GM-CSF receptor expression determines opposing innate memory phenotypes at different stages of myelopoiesis

AbstractInflammatory responses must be tightly coordinated with the activation of emergency myelopoiesis to produce potent myeloid cells that fight infection without causing excessive host damage. Here, we show that granulocyte-macrophage colony-stimulating factor (GM-CSF) programs myeloid-committed progenitors to produce trained macrophages (increased cytokine response), but programs the upstream noncommitted LKS+ progenitors (defined as Lin− c-Kit+ Sca-1+ cells) to produce tolerized macrophages (decreased cytokine response). In myeloid progenitors, GM-CSF strongly activates signal transducer and activator of transcription 5 (STAT5), Ras-Raf-extracellular signal regulated kinase (ERK), and Akt-mTOR signaling pathways, which are essential to establish a training program, whereas in LKS+ progenitors, GM-CSF induces NF-κB translocation to the nucleus to establish a tolerization program. These differences arise from higher GM-CSF receptor expression in myeloid progenitors compared with LKS+ cells. We demonstrate that β-catenin regulation of NF-κB nuclear translocation is central in this process. In myeloid progenitors, glycogen synthase kinase 3 (GSK3) inactivation by strong ERK and phosphatidylinositol 3 kinase (PI3K)-Akt signaling increases cytoplasmic β-catenin levels to block NF-κB nuclear translocation. In contrast, when ERK and PI3K-Akt signaling are weak, active GSK3 causes a decrease in β-catenin, allowing NF-κB nuclear translocation in LKS+ progenitors. Finally, GM-CSF-induced LKS+ tolerization takes place in several murine models of trained immunity and in human CD34+ CD38− progenitors. Our study reveals that in addition to activating myelopoiesis, GM-CSF also programs early and immediate myeloid progenitors to produce opposing immune memory phenotypes. We propose that the inflammatory response from immediate myeloid progenitors may be balanced by the tolerized phenotype of early progenitors, thus providing a mechanism for appropriate resolution of inflammation and protection against a prolonged cytokine storm.

Recognition of granulocyte-macrophage colony-stimulating factor by specific S100 proteins

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a pleiotropic myelopoietic growth factor and proinflammatory cytokine, clinically used for multiple indications and serving as a promising target for treatment of many disorders, including cancer, multiple sclerosis, rheumatoid arthritis, psoriasis, asthma, COVID-19. We have previously shown that dimeric Ca2+-bound forms of S100A6 and S100P proteins, members of the multifunctional S100 protein family, are specific to GM-CSF. To probe selectivity of these interactions, the affinity of recombinant human GM-CSF to dimeric Ca2+-loaded forms of 18 recombinant human S100 proteins was studied by surface plasmon resonance spectroscopy. Of them, only S100A4 protein specifically binds to GM-CSF with equilibrium dissociation constant, Kd, values of 0.3–2 μM, as confirmed by intrinsic fluorescence and chemical crosslinking data. Calcium removal prevents S100A4 binding to GM-CSF, whereas monomerization of S100A4/A6/P proteins disrupts S100A4/A6 interaction with GM-CSF and induces a slight decrease in S100P affinity for GM-CSF. Structural modelling indicates the presence in the GM-CSF molecule of a conserved S100A4/A6/P-binding site, consisting of the residues from its termini, helices I and III, some of which are involved in the interaction with GM-CSF receptors. The predicted involvement of the ‘hinge’ region and F89 residue of S100P in GM-CSF recognition was confirmed by mutagenesis. Examination of S100A4/A6/P ability to affect GM-CSF signaling showed that S100A4/A6 inhibit GM-CSF-induced suppression of viability of monocytic THP-1 cells. The ability of the S100 proteins to modulate GM-CSF activity is relevant to progression of various neoplasms and other diseases, according to bioinformatics analysis. The direct regulation of GM-CSF signaling by extracellular forms of the S100 proteins should be taken into account in the clinical use of GM-CSF and development of the therapeutic interventions targeting GM-CSF or its receptors.

Intestinal stroma guides monocyte differentiation to macrophages through GM-CSF

Stromal cells support epithelial cell and immune cell homeostasis and play an important role in inflammatory bowel disease (IBD) pathogenesis. Here, we quantify the stromal response to inflammation in pediatric IBD and reveal subset-specific inflammatory responses across colon segments and intestinal layers. Using data from a murine dynamic gut injury model and human ex vivo transcriptomic, protein and spatial analyses, we report that PDGFRA+CD142−/low fibroblasts and monocytes/macrophages co-localize in the intestine. In primary human fibroblast-monocyte co-cultures, intestinal PDGFRA+CD142−/low fibroblasts foster monocyte transition to CCR2+CD206+ macrophages through granulocyte-macrophage colony-stimulating factor (GM-CSF). Monocyte-derived CCR2+CD206+ cells from co-cultures have a phenotype similar to intestinal CCR2+CD206+ macrophages from newly diagnosed pediatric IBD patients, with high levels of PD-L1 and low levels of GM-CSF receptor. The study describes subset-specific changes in stromal responses to inflammation and suggests that the intestinal stroma guides intestinal macrophage differentiation.

Current Perspectives in Giant Cell Arteritis: Can We Better Connect Pathogenesis and Treatment?

Giant cell arteritis (GCA) is a large-vessel vasculitis affecting elderly patients and targeting the aorta and its main branches, leading to cranial and extracranial manifestations. The mechanism behind the ischemia is a granulomatous-type inflammation with potentially critical lesions, including visual loss involving the ophthalmic artery. Despite significant progress in unraveling the pathophysiology of this disease, treatment options still rely on glucocorticoids (GCs) to overcome active vascular lesions and disease flares. However, uncertainty still revolves around the optimal dose and tapering rhythm. Few corticosteroid-sparing agents have proven useful in GCA, namely, methotrexate and tocilizumab, benefiting cumulative GC dose and relapse-free intervals. The future looks promising with regard to using other agents like abatacept and Janus-kinase inhibitors or blocking the granulocyte-macrophage colony-stimulating factor receptor.

Ten-year experience of whole lung lavage in pediatric Pulmonary Alveolar Proteinosis.

Pulmonary Alveolar Proteinosis (PAP) is extremely rare and can be caused by hereditary dysfunction of the granulocyte macrophage colony-stimulating factor receptor (GM-CSF) receptor, autoantibodies against GM-CSF, or other diseases leading to alveolar macrophage (AM) dysfunction. This leads to protein accumulation in the lung and severe dyspnea and hypoxemia. Whole lung lavage (WLL) is the first line treatment strategy. Here, we present data from more than ten years of WLL practice in pediatric PAP. WLL performed by the use of a single lumen or double lumen tube (SLT vs. DLT) were compared for technical features, procedure time, and adverse events. A total of n=57 procedures in six PAP patients between 3.5 and 14.3 years of age were performed. SLT based WLL in smaller children was associated with comparable rates of adverse events but with longer intervention times and postprocedural intensive care treatment when compared to DLT based procedures. Our data shows that WLL is feasible even in small children. DLT based WLL seems to be more effective, and our data supports the notion that it should be considered as early as possible in pediatric PAP. WLL lavage is possible in small PAP patients but should performed in close interdisciplinary cooperation and with age appropriate protocols.

ЛЕГЕНЕВИЙ АЛЬВЕОЛЯРНИЙ ПРОТЕЇНОЗ: ВИПАДОК СУБТОТАЛЬНОГО УРАЖЕННЯ ПАРЕНХІМИ ЛЕГЕНЬ)

Pulmonary alveolar proteinosis (PAP) is a rare pulmonary disease, characterized by the intraalveolar accumulation of surfactant-like lipoprotein substance. There are three forms of the disease: autoimmune (formerly known as idiopathic), secondary and congenital PAP. The disturbances of surfactant metabolism (protein-lipoid complex secreted by type II pneumocytes) play the crucial role in the development of the disease. Surfactant decreases a surface tension of alveoli and prevents its collapse at the end of the expiration and takes part in protection against infections as well. Surfactant is inactivated through the transformation into the surface-inactive aggregates, which are mainly absorbed by type II pneumocytes. The rest of surfactant are catabolized by alveolar macrophages (AM). This process is regulated by cytokines, especially granulocyte-macrophage colony-stimulating factor (GM-CSF) being the most important of them. Disturbances of interrelation between GM-CSF and cellular receptors blocks the signals to effector cells for surfactant deactivation. This is resulted in excessive accumulation of surfactant in alveoli. General lavage of the lung is a standard method of symptomatic management of PAP. Contemporary pathogenesis treatment uses two approaches — increasing the clearance of surfactant by means of exogenous GM-CSF administration and decreasing the level of GM-CSF antibodies using the rituximab and plasmapheresis. Due to the use of broncho-alveolar lavage (BAL) 5-year survival rate of th patients reaches 95 %. The mortality depends on the area of lung lesion and reversely correlated with the timely diagnosis and treatment. We report the case of subtotal lung parenchyma lesion associated with severe respiratory failure in 46 years old patient. Three series of BAL (5 procedures in each with 1-2 months interval) were performed using the limited volume of lavage fluid due to the severity of the patient’s condition. The results was an improvement of clinical condition, resolution of respiratory failure, significant reduction of the size of the lesions, improved lung transparency on CT scan, restoration of lung diffusion and total lung capacity. Conclusion. Therapeutic BAL is an effective method of PAP management. The outcome of clinical case presented and our many years experience confirm not only the effectiveness of conventional BAL with reduced lavage volume application but also a safety of fiberoptic bronchoscopy, especially in patients with subtotal involvement of lung parenchyma. Key words: pulmonary alveolar proteinosis, subtotal pulmonary parenchyma involvement, pulmonary bronchoalveolar lavage, efficiency.

Hereditary Pulmonary Alveolar Proteinosis in a Pediatric Patient – A Diagnostic and Therapeutic Challenge

Abstract The abstract will be: “Pulmonary Alveolar Proteinosis (PAP) is a rare but potentially fatal respiratory disorder. The hereditary form is due to mutations affecting the GM-CSF receptor subunits. We are presenting this case report of a 3-year-old girl -who was the child of a fourth-degree consanguineous marriage- who developed Hereditary Alveolar Proteinosis. Her diagnosis was confirmed by surgical biopsy as well as whole exome sequencing (WES) genetic testing that revealed homozygous gene deletion of the CSF2RA gene (Colony Stimulating Factor 2RA). She had a favorable outcome and spontaneous resolution of her disease on follow-up.”

GATA1 Target Gene CSF2RB Is Functionally Coupled to MPL and Marks a TPO-Dependent Preleukemic TAM Cell Population Sustained By the Fetal Liver but Not Bone Marrow

Paediatric cancers differ from adult cancers on the basis of their genetics and biology. Understanding these differences can identify factors important in oncogenesis during development. One exemplar are the genetically linked myeloid pre-leukemic and leukemic disorders in newborns and children with Trisomy 21 (T21) or Down syndrome (DS). DS children have a 400-fold increased risk of developing myeloid leukemia (ML-DS) in early life. ML-DS is preceded by a fetal/neonatal pre-leukemic phase known as transient abnormal myelopoiesis (TAM), when T21 hemopoietic cells acquire mutations in the GATA1 gene. These mutations produce an N-terminal truncated GATA1 protein (GATA1s). Remarkably, the proliferative effect exerted by T21 and GATA1s is developmentally restricted. As hemopoiesis shifts from fetal liver to new-born bone marrow, TAM usually spontaneously regresses. The biological basis for the requirement of a fetal liver environment for TAM cells and their failure to thrive in the bone marrow is unknown. However, a clue is that TAM cells can proliferate in bone marrow if they acquire oncogenic mutations, typically in genes of the JAK-STAT signalling pathway. These mutations transform the TAM clone to an ML-DS clone. To address the question of why TAM cells survive only in a fetal liver environment, we performed scRNA sequencing, coupled with genotyping from 3 primary TAM samples. 4 T21 and 3 disomic cord blood samples were used as controls (Fig1A). We identified a marked expansion of mutant TAM GATA1s cells, compared to controls, at the earliest GATA1-expressing progenitor stages (Fig1A). TAM GATA1s cells displayed transcriptional upregulation of the PI3K/AKT/mTOR, TNFA/NFκB and JAK/STAT pathways and enhanced STAT3 regulon activity when compared to controls (Fig1A). We hypothesized that aberrant cytokine receptor activation leading to increased STAT3 activity is essential for GATA1s cell proliferation. Differential gene expression between TAM GATA1s cells and disomic cells, pointed to CSF2RB, a cytokine receptor that directly activates the JAK-STAT signalling pathway (Fig1A). Next, we demonstrated that CSF2RB is overexpressed at the protein level in TAM and marks 80% of CD34 + cells compared to 5% CD34+ control cells. Using CUT&TAG we confirmed binding of GATA1s and GATA2 at two GATA sites in the CSF2RB locus in CMK cells (Fig 1A). CRISPR-Cas9 disruption of either GATA2, or the -12kb GATA motif led to downregulation of CSF2RB protein (Fig1A). We are testing if GATA1 represses CSF2RB and whether GATA1s fails to repress CSF2RB, allowing sustained abnormal CSF2RB expression in TAM. CSF2RB gene knockout in GATA1s cells leads to cell death. Taken together, CSF2RB is a direct GATA target gene and abnormal sustained, CSF2RB expression in TAM cells is required for GATA1s cell survival. Classically, CSF2RB partners with the α-chain of either IL3, IL5 or GMCSF receptors. Interestingly, none of the α-chains are expressed at the protein or RNA level in TAM CSF2RB+ cells, suggesting that CSF2RB might partner with another cytokine receptor. We nominated MPL, the thrombopoietin (TPO) receptor as a new candidate binding partner of CSF2RB for the following reasons: (i) we documented co-expression of MPL with CSF2RB at the RNA and protein level in TAM cells. (ii) we confirmed functional coupling between CSF2RB and MPL in Ba/F3 and TF-1 cells, where at equivalent MPL levels, TPO signalling via the JAK-STAT pathway is enhanced by CSF2RB. This effect is stronger at high TPO levels. (iii) A mutation in CSFR2RB (A455D) that we described in ML-DSrequires interaction with human MPL to induce autonomous growth of cytokine-dependent hematopoietic cells. Notably, direct interaction between MPL and CSF2RB A455D is detected by BRET assays. We hypothesize that high levels of fetal liver derived TPO sustain TAM proliferation because of the functional coupling between MPL and CSF2RB (Fig1B). This proliferation signal is lost as cells migrate to the low TPO bone marrow environment. Further work will assess TPO concentration in DS fetal liver and whether TAM cells display increased proliferation in response to varying TPO doses. In summary, we propose a model whereby reduced TPO levels experienced by TAM cells as they migrate from fetal liver to bone marrow creates selective pressure for acquisition of secondary mutations that permit TAM cells to proliferate independently of the high TPO environment of the fetal liver (Fig1B).

Role of GM-CSF in lung balance and disease.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a hematopoietic growth factor originally identified as a stimulus that induces the differentiation of bone marrow progenitor cells into granulocytes and macrophages. GM-CSF is now considered to be a multi-origin and pleiotropic cytokine. GM-CSF receptor signals activate JAK2 and induce nuclear signals through the JAK-STAT, MAPK, PI3K, and other pathways. In addition to promoting the metabolism of pulmonary surfactant and the maturation and differentiation of alveolar macrophages, GM-CSF plays a key role in interstitial lung disease, allergic lung disease, alcoholic lung disease, and pulmonary bacterial, fungal, and viral infections. This article reviews the latest knowledge on the relationship between GM-CSF and lung balance and lung disease, and indicates that there is much more to GM-CSF than its name suggests.

The divergent role of the GM-CSF/GM-CSFR signaling pathway in cholangiocarcinoma and pancreatic ductal adenocarcinoma.

736 Background: The granulocyte-macrophage colony-stimulating factor ligand and receptor (GM-CSF/GM-CSFR) pathway plays a multifaceted role in the setting of cancer, exerting an anti-tumorigenic or pro-tumorigenic effect depending on GM-CSF expression. In previous work, we and others have shown increased GM-CSF expression to correlate with poor prognosis in patients with cholangiocarcinoma (CCA) and pancreatic ductal adenocarcinoma (PDAC). We also demonstrated how GM-CSF neutralization leads to reduced tumor size in murine CCA models, in part due to inhibition of alternative macrophage polarization. Here, we explore the impact of blocking GM-CSFR signaling in CCA and PDAC, two immunologically cold tumors with poor prognoses. Methods: Immunohistochemistry (IHC) and digital quantification of staining was performed on tissue from a human PDAC and CCA databank. Murine F4/80+ bone marrow-derived macrophages were cultured in tumor-conditioned media (TCM) derived from PDAC (KP2) or CCA (URCCA4.3) cell lines, with and without anti-GM-CSFR antibody. Quantitative real time PCR (qRT-PCR) analysis was performed for gene expression. URCCA4.3 and a luciferase-labeled PDAC (KCKO) cell line were orthotopically implanted into Bc/BIL3 knockout (KO) mice which lack GM-CSFR and C57BL/6 mice. Mice implanted with URCCA4.3 were enrolled into vehicle or gemcitabine treatment groups. Mice implanted with KCKO were untreated. Tumor growth was monitored by ultrasonography or bioluminescence imaging. Results: Digital analysis of IHC staining for GM-CSFR in human PDAC tumors revealed low expression to be associated with improved overall survival (OS) and greater number of days to recurrence, while high levels were associated with worse OS and fewer days to recurrence (p<0.01). In addition, human CCA specimens had greater GM-CSFR expression compared to normal uninvolved liver (p<0.01). qRT-PCR analysis of RNA from bone marrow-derived macrophages exposed to either CCA or PDAC TCM demonstrated lower expression of genes associated with alternative macrophage polarization ( Arg1, Cd274, Pdcd1lg2) and chronic inflammation ( Ccl2, Ccl17, Irf4) (all p<0.01) in response to GM-CSFR blockade. GM-CSFR KO mice implanted with URCCA4.3 demonstrated no differences in tumor growth with or without chemotherapy, compared to wild-type controls. Similarly, KO mice implanted with an immunogenic PDAC cell line (KCKO) had no differences in tumor size compared to wild-type controls. Conclusions: GM-CSFR expression is prognostic in the setting of PDAC and elevated in human CCA compared to normal liver. In vitro, GM-CSFR blockade downregulated pro-tumor genes associated with immunosuppression and inflammation. However, complete disruption of GM-CSFR signaling reversed the efficacy generated with GM-CSF ligand neutralization, suggesting some signaling is required for inducing anti-tumor immune responses.

Granulocyte-macrophage colony-stimulating factor: Conductor of the wound healing orchestra?

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a glycoprotein and is derived from both hemopoietic and nonhemopoietic sources which exert immunomodulatory properties. Various theories have been proposed to explain why some wounds become chronic and non-healing. Generalized suppression of inflammation locally or systemically may impede the body's physiological healing response by crippling the activity of reparative cells within the wound ecosystem. Thus, highlighting the importance of promoting host-directed therapeutics with immunomodulatory properties. The temporal and spatial expression of GM-CSF and GM-CSF receptors in the integumentary system suggests that epithelial-derived GM-CSF functions in an autocrine/paracrine manner. This may positively affect wound healing physiology via local inflammatory regulation promoting macrophage survival. Although diabetes negatively affects multiple aspects of wound healing GM-CSF activation is particularly impacted. Compared to acute/healthy wounds diabetic foot ulcers (DFU) only partially activate GM-CSF activity. There is a deleterious chain of events associated with this unfortunate sequala. DFUs also have a high proportion of monocytes and an absence of activated macrophages which results in an impaired inflammatory response. This may potentially serve as a vital point for GM-CSF to act as a companion diagnostic/theragnostic modality to help modulate the inflammatory response in wound healing. Correcting macrophage immune dysfunction with exogenous GM-CSF may help restore the immune balance in the wound ecosystem and jumpstart the wound healing cascade. Thus, the recognized beneficial role of GM-CSF in immune regulation across many studies provides a rationale for the initiation of the ongoing randomized controlled trials using GM-CSF.

SHP-2 and PD-1-SHP-2 signaling regulate myeloid cell differentiation and antitumor responses

The inhibitory receptor PD-1 suppresses T cell activation by recruiting the phosphatase SHP-2. However, mice with a T-cell-specific deletion of SHP-2 do not have improved antitumor immunity. Here we showed that mice with conditional targeting of SHP-2 in myeloid cells, but not in T cells, had diminished tumor growth. RNA sequencing (RNA-seq) followed by gene set enrichment analysis indicated the presence of polymorphonuclear myeloid-derived suppressor cells and tumor-associated macrophages (TAMs) with enriched gene expression profiles of enhanced differentiation, activation and expression of immunostimulatory molecules. In mice with conditional targeting of PD-1 in myeloid cells, which also displayed diminished tumor growth, TAMs had gene expression profiles enriched for myeloid differentiation, activation and leukocyte-mediated immunity displaying >50% overlap with enriched profiles of SHP-2-deficient TAMs. In bone marrow, GM-CSF induced the phosphorylation of PD-1 and recruitment of PD-1-SHP-2 to the GM-CSF receptor. Deletion of SHP-2 or PD-1 enhanced GM-CSF-mediated phosphorylation of the transcription factors HOXA10 and IRF8, which regulate myeloid differentiation and monocytic-moDC lineage commitment, respectively. Thus, SHP-2 and PD-1-SHP-2 signaling restrained myelocyte differentiation resulting in a myeloid landscape that suppressed antitumor immunity.

Dissecting the role of CSF2RB expression in human regulatory T cells.

Colony stimulating factor 2 receptor subunit beta (CSF2RB; CD131) is the common subunit of the type I cytokine receptors for granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-3 and IL-5. Interestingly, FOXP3+ regulatory T cells (Tregs), which play a pivotal role in prevention of autoimmunity have been demonstrated to highly overexpress CSF2RB and genome-wide association studies (GWAS) identified CSF2RB as being linked to autoimmune diseases like multiple sclerosis (MS). However, the exact biological role of CD131 in human Tregs has not been defined yet. Here we investigated CD131 importance on Treg phenotype and function in a broad range of in vitro studies. Although we could not recognize a specific function of CSF2RB; CD131 in human Tregs, our data show that CD131 expression is vastly restricted to Tregs even under stimulatory conditions, indicating that CD131 could aid as a potential marker to identify Treg subpopulations from pools of activated CD4+ T cells. Importantly, our analysis further demonstrate the overexpression of CSF2RB in Tregs of patients with autoimmune diseases like MS and systemic lupus erythematosus (SLE) in comparison to healthy controls, thereby indicating that CSF2RB expression in Tregs could serve as a potential novel biomarker for disease.

SHP-2 Regulates Myeloid Cell Differentiation, Anti-Tumor Responses and Innate Immune Memory

PD-1 is a T cell checkpoint inhibitor and the most extensively exploited therapeutic target of cancer immunotherapy. PD-1-mediated T cell inactivation is attributed to the function of SHP-2 phosphatase, which is activated by recruitment to PD-1 cytoplasmic tail. However, T cell-specific SHP-2 deletion did not improve anti-tumor immunity or altered responses to anti-PD-1 immunotherapy. Previously, we determined that PD-1 is also expressed in common myeloid progenitors and granulocyte/macrophage progenitors, which accumulate during cancer-driven emergency myelopoiesis and give rise to immunosuppressive myeloid-derived suppressor cells (MDSC) and tumor-associated macrophages (TAMs). In tumor-bearing mice with myeloid-specific PD-1 ablation, accumulation of MDSCs was prevented, while output of differentiated effector myeloid cells with monocytic lineage dominance was increased. However, the molecular mechanism remains elusive. It is also unknown whether a canonical PD-1:SHP-2 axis is operative in myeloid cells. Temporal activation of SHP-2 is critical for myeloid cell fate. Gain of function SHP-2 mutations, resulting in constitutive phosphatase activation, prevent myeloid differentiation and lead to the accumulation of immature myelocytes and development of leukemia. HOXA proteins, members of the HOX family of transcription factors involved in normal hematopoiesis, are targets of SHP-2, which dephosphorylates HOXA and prevents derepressing of HOXA target genes and myeloid cell differentiation. In addition, SHP-2 regulates the function of IFN regulatory factor (IRF)-8, a transcription factor that has a decisive role in myeloid progenitor differentiation toward monocytes and DCs. IRF8 phosphorylation is mandatory for its nuclear translocation and initiation of gene transcription. The cytoplasmic-nuclear shuttling of IRF8 is regulated by SHP-2, which dephosphorylates IRF8 and prevents its nuclear localization and transcriptional activation. We generated mice with conditional targeting of the Ptpn11 gene (encoding for Shp-2) in T cells (Shp2f/fLckCre) or myeloid cells (Shp2f/fLysMCre), and found that Shp2f/fLysMCre but not Shp2f/fLckCre mice had diminished tumor growth. As determined by RNA-sequencing, this was paralleled by the presence of inflammatory neutrophils and tumor-associated macrophages (TAMs) with molecular signatures of enhanced differentiation, phagocytosis and antigen-processing and presentation. SHP-2 deficient TAMs also had increased monocyte and dendritic cells (DCs) specification transcription factors, chemokine and cytokine production, and expression of immunostimulatory molecules that promote T cell recruitment and activation. Moreover, monocytes from tumor-bearing Shp2f/fLysMCre mice suppressed tumor growth after transfer to naïve recipients indicating development of innate immune memory, named trained immunity. In bone marrow myelocytes, SHP-2 deletion enhanced GM-CSF-mediated phosphorylation of the transcription factors HOXA10 and IRF8 that promote myeloid differentiation and monocytic/moDC lineage commitment, respectively. In contrast, in WT bone marrow myelocytes GM-CSF induced PD-1 expression, phosphorylation and interaction with SHP-2, the Src family kinase Lyn, and GM-CSF receptor beta chain, indicating that the PD-1:SHP-2 axis targets a key pathway of myelocyte differentiation. Our results reveal a previously unidentified mechanistic role of SHP-2 and the PD-1:SHP-2 axis in regulating myeloid cell differentiation in the context of cancer and provide evidence that SHP-2 poses a signaling restrain to myeloid differentiation and monocyte lineage commitment resulting in a myeloid landscape that suppresses anti-tumor immunity. This process is hijacked by the PD-1/PD-L1 pathway.

Congenital Pulmonary Alveolar Proteinosis: An Exceptional Cause of Diffuse Interstitial Lung Disease

Introduction: Pulmonary alveolar proteinosis is a rare respiratory disease characterized by the accumulation of surfactant-derived material in the lungs. It is commonly revealed by progressively increasing exertional dyspnoea contrasting with a poor clinical examination in the context of a diffuse infiltrating pneumonia. Bronchoalveolar lavage is the key to diagnosis. Genetic PAPs are usually diagnosed at birth or in childhood. PAPs of genetic origin mainly include surfactant production disorders, lysinuric protein intolerances and mutations of the GM-CSF receptor. CSF treatment is ineffective. On the other hand, large therapeutic lung lavage seems to be effective. The course of PAP is variable, ranging from spontaneous resolution to death from respiratory failure or lung infection. Case Report: A 3- month-old girl with family history of first-degree consanguineous parents, who was having a background of a Progressive worsening of respiratory symptoms and who was referred to our department for the treatment of diffuse pneumonia. The respiratory functional explorations objectified a restrictive syndrome. Chest X-ray revealed Bilateral alveolar-interstitial syndrome with left basal condensation and a Chest CT scan showed diffuse infiltrating pneumopathy, reasons why a bronchoalveolar lavage was performed showing a milky appearance. It contains a large amount of proteinaceous eosinophilic acellular granular material, which is PAS - positive. There are also foamy macrophages with PAS-positive intracellular inclusions. Those data are consistent with the diagnosis of PAP. The genetic study had shown an alpha chain mutation of the GM-CSF receptor confirming the diagnosis of primary alveolar proteinosis of genetic origin. The Evolution After two therapeutic bronchoalveolar lavages of both lungs was favorable with a clear decrease in pulmonary signs of effort. Conclusion: Alveolar proteinosis is a rare etiology of chronic interstitial lung disease in children. The diagnosis of certainty is do ne thanks to BAL and the treatment is based on therapeutic BAL sessions. The primitive forms are frequent and their prognosis seems be inversely correlated with age at onset.