Laravel: orderby count on pivot while filtering parent with keyword

Good morning everybody,

I have two tables, users, questions and one pivot table users_questions. A question belongs to many users. A user has many questions.

users
-----
id | name

questions
---------
id | description

users_questions
---------------
user_id | question_id

I would like to get the top 3 users who asked the most questions for a specific keyword.

To search a keyword inside a question, I use a simple filter package. The code looks like that:

Questions::with('user')
        ->filter()
        ->paginate();

To get the 3 users who asked the most questions without filtering anything, I wrote this code:

UsersQuestions::with('user')
            ->select('mep_id')
            ->selectRaw('COUNT(*) AS count')
            ->groupBy('user_id')
            ->orderByDesc('count')
            ->limit(3)
            ->get();

But I can not figure out how to “mix” those two requests together.

Thanks in advance for your help!