Task: Text Simplification
Input (English): Psychoneuroimmunology ( PNI ) , also referred to as psychoendoneuroimmunology ( PENI ) or psychoneuroendocrinoimmunology ( PNEI ) , is the study of the interaction between psychological processes and the nervous and immune systems of the human body .
Output (English): Psychoneuroimmunology ( PNI ) is the study of the interaction between psychological processes and the nervous and immune systems of the human body .