MMP9 and pneumonia: Acquired immunodeficiency syndrome (AIDS) pneumonia patients show a higher microbiota diversity than AIDS-free pneumonia patients.201 In a case of 60 Ugandan AIDS patients who had their pneumonia treated with antimicrobial therapy, those with decreased airway bacterial diversity showed an increased bacterial load and increased expression of matrix metalloproteinase (MMP)−9 and pro-inflammatory TNF-α.202 In addition, the differences in the lower respiratory groups of patients with advanced human immunodeficiency virus (HIV) are much greater than those of healthy individuals.