What is the significance of port 49153?

There is a wealth of knowledge on well known ports like port 49153 available on the internet and the services that run behind them. I would recommend researching the hardening of the IIS / Windows server and go from there. It's good that you've taken a proactive approach to assess your web server, and understand how it functions. It's not uncommon for known good services to initiate communications and open ports dynamically, so even if your research to a high number port comes empty handed it's not necessarily something to worry about. For the most part Windows IIS is pretty secure out of the box and doesn't require too much tweaking, but just ensure that you're updating your server with patches regularly. These days most attackers will focus on the web application running on your server, rather than attacking the server itself.

Using TCPView will also provide you with a look into what services are utilising the ports.