Lowercase property names from Json() in .Net core

Have class ClientViewModel:

public class Result
{      
  public long PKID
  {
      get;
      set;
  }

   public string Name
   { 
      get; 
      set; 
   }
}

And have post method to return this model:

[HttpPost]
    public JsonResult Search(string orderBy, List<Order> order, Search search,
        int start, int length, string searchTerm, bool isAsc, bool hideVoidedAndDeclined, bool recent = false)
    {
        var take = length;
        var skip = start;
        var m = _clientsService.Search(searchTerm, orderBy, hideVoidedAndDeclined, isAsc, take, skip, recent);


        return Json(m);
    }

but when try to return object in json it looks as:

name:"Nick22"
pkid: 5

But i need to save register

Name:"Nick22"
PKID: 5