CD8A and neoplasm: Certain metabolites of Lactobacillus also have direct tumor-suppressive roles, γ-linolenic acid from Lactobacillus plantarum MM89 induce ferroptosis in colorectal cancer cells 158, reuterin from Lactobacillus reuteri disrupts redox homeostasis to inhibit tumor growth 159, and indole derivatives such as IAA, ICA, ILA, and IPA from Lactobacillus modulate Treg differentiation, enhance dendritic cell function, and reprogram CD8+ T cell chromatin accessibility to strengthen antitumor immunity and improve responses to immunotherapy 125, 160-162.