FOXP3+ regulatory T cells are associated with the severity and prognosis of sarcoidosis

Insights on immune profile, pathogenesis and differential diagnosis of hypersensitivity pneumonitis and pulmonary sarcoidosis-A holistic review and bibliometric analysis

Hypersensitivity pneumonitis (HP) and sarcoidosis are granulomatous interstitial lung diseases with overlapping clinical and immunological features, posing diagnostic and therapeutic challenges. This review offers a comprehensive assessment of their immune mechanisms, etiology, and pathogenesis. HP is predominantly triggered by exposure to environmental antigens, while sarcoidosis involves an exaggerated immune response to elusive antigens. Both diseases are driven by Th1 and Th17 pathways, regulatory T-cell dysfunction, and cytokine-mediated granuloma formation. Emerging diagnostic and prognostic biomarkers, such as KL-6, GDF15, PD-1, TIGIT, and genetic regulators including m6A and m5C modifications, provide valuable insights for disease stratification. Incorporating findings from a total of 38 studies (HP: n = 13; sarcoidosis: n = 25) published in the last 5 years, this review highlights key immune regulatory mechanisms, identifies critical research gaps, and provides directions for improving differential diagnosis. Addressing these gaps through multi-omics integration, computational tools, and interdisciplinary collaboration holds significant potential for refining diagnostic accuracy, advancing therapeutic strategies, and improving patient outcomes in both HP and sarcoidosis.

Beyond the Granuloma: New Insights into Cardiac Sarcoidosis Using Spatial Proteomics

Cardiac sarcoidosis is poorly understood, challenging to diagnose, and portends a poor prognosis. A lack of animal models necessitates the use of residual human samples to study sarcoidosis, which in turn necessitates the use of analytical tools compatible with archival, fixed tissue. We employed high-plex spatial protein analysis within a large cohort of archival human cardiac sarcoidosis and control tissue samples, studying the immunologic, fibrotic, and metabolic landscape of sarcoidosis at different stages of disease, in different cardiac tissue compartments, and in tissue regions with and without overt inflammation. Utilizing a small set of differentially expressed protein biomarkers, we also report the development of a predictive model capable of accurately discriminating between control cardiac tissue and sarcoidosis tissue, even when no histologic evidence of sarcoidosis is present. This finding has major translational implications, with the potential to markedly improve the diagnostic yield of clinical biopsies obtained from suspected sarcoidosis patients.

Regulatory T cells: Supporting lung homeostasis and promoting resolution and repair after lung injury

Regulatory T cells, characterized by their expression of the transcription factor Forkhead box P3, are indispensable in maintaining immune homeostasis. The respiratory system is constantly exposed to many environmental challenges, making it susceptible to various insults and infections. Regulatory T cells play essential roles in maintaining homeostasis in the lung and promoting repair after injury. Regulatory T cell function dysregulation can lead to inflammation, tissue damage, or aberrant repair. Research on regulatory T cell mechanisms in the lung has unveiled their influence on lung inflammation and repair mechanisms. In this review, our goal is to highlight the advances in regulatory T cell biology with respect to lung injury and resolution. We further provide a perspective that a deeper understanding of regulatory T cell interactions in the lung microenvironment in health and disease states offers opportunities for therapeutic interventions as treatments to promote lung health.