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Eunjae Kim, Disha Varma, llangovan Raju, Zhiqiang Liu, Anubhav Pradeep, Christine Mun, Joy Sarkar, Sandeep Jain; Semaphorin 7a is differentially expressed in myeloid-derived suppressor cells (MDSCs) in naïve and inflammatory conditions.. Invest. Ophthalmol. Vis. Sci. 2016;57(12):4919.
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© ARVO (1962-2015); The Authors (2016-present)
We investigated the expression of neurotrophic factors, Semaphorin 7a (Sema7a) and nerve growth factors (NGF), in MDSCs in naïve, wound healing and inflammatory conditions and determined the viability of MDSCs under these conditions.
YFP fluorescent MDSCs were harvested from bone marrow of thy-1 YFP+ mice (8-10week old) and sorted using the Legacy MoFlo cell sorter. Sorted MDSCs (>95% purity) were used for all assays. qPCR was performed after 3 days of culture for expression of Sema7a and NGF, and cell viability was determined using a dimeric cyanine nucleic acid stain over 60 hours. MDSCs were cultured in DMEM under various conditions (serum free for naïve condition, 10% FBS addition for wound healing condition and GM-CSF addition for inflammatory condition). Similar conditions (naïve, 1M NaOH corneal alkali burn for inflammatory condition, epithelial debridement for wound healing condition, and laser transection of corneal stromal nerves for neurotrophic condition) were created in vivo in thy1-YFP mouse (n=5/group).
MDSCs showed significant difference in the expression levels of neurotrophic factors under various culture conditions. NGF, but not Sema7a, was expressed in serum free condition and after addition of 10% FBS (wound healing condition). A significant increase in Sema7a expression was noticed after GM-CSF addition (inflammatory condition). The viability of MDSCs was highest in the inflammatory culture condition. In vivo data showed that Sema7a was significantly expressed in neurotrophic cornea and alkali burn cornea. In naïve corneas NGF was expressed but not Sema7a. In corneas with epithelial debridement only (superficial nerves injured but intact stromal nerves), NGF expression was upregulated, but not Sema7a.
Sema7a is expressed by murine MDSCs and corneas under inflammatory conditions. Injury to stromal nerve trunks in the cornea, but not the subepithelial nerve plexus, causes upregulation of Sema7a. These findings suggest that in naïve cornea and under wound healing conditions NGF is predominantly expressed neurotrophic factor. However, in inflammatory and neurotrophic conditions, Sema7a is the predominantly expressed neurotrophic factor.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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