Probes for INS

Chronic microglial activation and associated neuroinflammation are key factors in neurodegenerative diseases including HIV-associated neurocognitive disorders. Colony stimulating factor 1 receptor (CSF1R)-mediated signaling is constitutive in cells of the myeloid lineage, including microglia, promoting cell survival, proliferation, and differentiation. In amyotrophic lateral sclerosis and Alzheimers disease, CSF1R is upregulated. Inhibiting CSF1R signaling in animal models of these diseases improved disease outcomes. In our studies, CNS expression of the CSF1R ligand, colony-stimulating factor 1 (CSF1) was significantly increased in a SIV/macaque model of HIV CNS disease. Using a Nanostring nCounter immune panel, we found CSF1 overexpression was strongly correlated with upregulation of microglial genes involved in antiviral and oxidative stress responses. Using in situ hybridization, we found that CSF1R mRNA was only present in Iba-1 positive microglia. By ELISA and immunostaining with digital image analysis, SIV-infected macaques had significantly higher CSF1R levels in frontal cortex than uninfected macaques (p = 0.018 and p = 0.02, respectively). SIV-infected macaques treated with suppressive ART also had persistently elevated CSF1R similar to untreated SIV-infected macaques. Coordinate upregulation of CSF1 and CSF1R expression implicates this signaling pathway in progressive HIV CNS disease.

Resistance to current therapies still impacts a significant number of melanoma patients and can be regulated by epigenetic alterations. Analysis of global cytosine methylation in a cohort of primary melanomas revealed a pattern of early demethylation associated with overexpression of oncogenic transcripts. Loss of methylation and associated overexpression of the CSF 1 receptor (CSF1R) was seen in a majority of tumors and was driven by an alternative, endogenous viral promoter in a subset of samples. CSF1R was particularly elevated in melanomas with BRAF and other MAPK activating mutations. Furthermore, rebound ERK activation after BRAF inhibition was associated with RUNX1-mediated further upregulation of CSF-1R and its ligand IL-34. Importantly, increased CSF-1R and IL-34 overexpression were detected in an independent cohort of resistant melanomas. Inhibition of CSF-1R kinase or decreased CSF-1R expression by RNAi reduced 3-D growth and invasiveness of melanoma cells. Coinhibition of CSF-1R and BRAF resulted in synergistic efficacy in vivo. To our knowledge, our data unveil a previously unknown role for the autocrine-regulated CSF-1R in BRAF V600E resistance and provide a preclinical rationale for targeting this pathway in melanoma.

Colony-stimulating factor 1 (CSF1) controls the growth and differentiation of macrophages.CSF1R signaling has been implicated in the maintenance of the intestinal stem cell niche and differentiation of Paneth cells, but evidence of expression of CSF1R within the crypt is equivocal. Here we show that CSF1R-dependent macrophages influence intestinal epithelial differentiation and homeostasis. In the intestinallamina propria CSF1R mRNA expression is restricted to macrophages which are intimately associated with the crypt epithelium, and is undetectable in Paneth cells. Macrophage ablation following CSF1R blockade affects Paneth cell differentiation and leads to a reduction of Lgr5+ intestinal stem cells. The disturbances to the crypt caused by macrophage depletion adversely affect the subsequent differentiation of intestinal epithelial cell lineages. Goblet cell density is enhanced, whereas the development of M cells in Peyer's patches is impeded. We suggest that modification of the phenotype or abundance of macrophages in the gut wall alters the development of the intestinal epithelium and the ability to sample gut antigens.