Tuberculosis (TB) continues to be a leading global health challenge, affecting more than 10 million people annually and claiming around 1.25 million lives each year. While steroids such as dexamethasone are commonly used in specific TB cases like TB meningitis, their impact on immune cells has remained poorly understood.
Exploring the Role of Dexamethasone in TB Treatment
Amid renewed global attention to dexamethasone—especially after its use as a host-directed therapy during the COVID-19 pandemic—researchers from Trinity College Dublin, based at St James’s Hospital, investigated how this steroid influences immune cell function in TB. Their findings, published in Scientific Reports, reveal that dexamethasone may enhance the macrophages’ ability to kill Mycobacterium tuberculosis (Mtb) while simultaneously reducing harmful inflammation.
Understanding the Research Approach
As reported by medicalxpress, the team aimed to determine how dexamethasone affects the macrophage’s ability to fight TB. Although glucocorticoids are sometimes linked to TB reactivation, they remain the only adjunctive host-directed therapy endorsed by the World Health Organization (WHO) for certain TB cases.
To explore this paradox, researchers studied macrophages derived from healthy volunteers’ blood and lung fluid obtained from patients undergoing routine bronchoscopies. By infecting these immune cells with Mtb in the laboratory, they examined how dexamethasone influences the macrophage response during infection.
Key Findings from the Study
- Reduced Energy Use but Balanced Inflammation
Dexamethasone, a potent glucocorticoid, reduces glycolysis in both lung and blood-derived macrophages—limiting energy production but also reducing excessive inflammation. It decreased the production of key cytokines, including IL-1β, TNF, IL-6, IL-8, and IL-10, which are involved in immune signaling. This balance helps the immune system fight infection while preventing tissue damage. - Enhanced Macrophage Survival and Function
The study found that Mtb-infected macrophages survived longer when treated with dexamethasone. This suggests that the drug may protect immune cells from dying due to infection or harmful immune responses. - Improved Bacterial Clearance
Remarkably, dexamethasone reduced bacterial burden in infected macrophages. The researchers identified that this effect is mediated through autophagy and phagosomal acidification—processes that help macrophages degrade and clear bacteria more efficiently. - Differences Between Lung and Blood Macrophages
The study also revealed that macrophages from different tissues respond differently to glucocorticoids. This finding underscores the importance of tissue-specific drug responses in designing future TB therapies.
Implications for TB Treatment and Patient Care
These findings suggest that steroids like dexamethasone can reduce inflammation without weakening antimicrobial defense. Therefore, combining steroids with existing antimicrobial therapies could accelerate recovery and improve outcomes in TB patients—especially those suffering from severe inflammation.
Moreover, steroids might play a role in preventive TB therapy, potentially helping to halt the progression from latent infection to active disease. This opens exciting new avenues for macrophage-targeted steroid therapies that carefully balance immune suppression and bacterial clearance.
Expert Perspectives
Dr. Donal Cox, Senior Research Fellow in Clinical Medicine at Trinity College Dublin, stated, “Our study shows that dexamethasone, known for dampening inflammation, can also help macrophages fight tuberculosis more effectively. This challenges the assumption that steroids always suppress immunity and opens the door to smarter, targeted adjunctive therapies.”
Prof. Joseph Keane, Professor of Medicine at Trinity College Dublin and Consultant Respiratory Physician at St James’s Hospital, added, “Steroids are often underused in TB care. This study reassures us that dexamethasone not only controls inflammation but also supports macrophages in fighting infection. It’s time to rethink how we use steroids to enhance TB treatment.”
Future Directions: Toward Smarter Steroid Therapies
The research team now aims to develop targeted steroid delivery methods, such as inhaled nanoparticles, to direct treatment specifically to lung macrophages—the primary site of TB infection. They also plan to study how steroids alter metabolic pathways in different macrophage types, paving the way for next-generation, precision-based therapies for tuberculosis.
A Step Forward in Combating TB
In summary, this groundbreaking study provides fresh insights into how dexamethasone can balance inflammation control with bacterial clearance, redefining the role of steroids in TB management. The findings bring hope for more effective, targeted treatments that could shorten recovery time and improve quality of life for millions affected by tuberculosis worldwide.