TNF and depressive disorder: Second, while the study's focus on the role of IL-6 as a broad marker of peripheral proinflammatory activity (Roohi et al., 2021) provides a valuable entry point, IL-6 alone may not capture the full complexity of the inflammatory profile involved in depression or its inflammatory subtype, which involves additional cytokines such as IL-1β and TNF-α (Ahmed, 2011).