Tocilizumab Induces IL-10-Mediated Immune Tolerance in Invasive Candidiasis

Area of Science:

• Immunology
• Infectious Diseases
• Pharmacology

Background:

• Invasive fungal infections (IFI) can trigger hyperinflammatory states, potentially causing host tissue damage and adverse outcomes.
• Exaggerated inflammatory responses, particularly involving interleukin-6 (IL-6), may contribute to morbidity in IFI patients with compromised immunity.
• Tocilizumab is an established immunomodulator used in treating inflammatory conditions.

Purpose of the Study:

• To evaluate the efficacy of tocilizumab in mitigating post-infective inflammatory responses in a mouse model of invasive candidiasis.
• To investigate the impact of tocilizumab on immune cell populations and cytokine profiles during invasive fungal infection.

Main Methods:

• An in-vivo mouse model of invasive candidiasis was established.
• Mice were treated with tocilizumab or saline following Candida infection.
• Immune responses, including cytokine levels (IL-6, IL-10, TNF-α, IFN-γ) and specific dendritic cell (DC) subsets (CD8α+ conventional DCs, CD11b+ conventional DCs, plasmacytoid DCs), were analyzed.

Main Results:

• Tocilizumab treatment led to improved short-term survival compared to saline controls.
• A reduced host inflammatory response was observed in tocilizumab-treated mice.
• Tocilizumab modulated cytokine levels, decreasing IL-6 and increasing IL-10, while TNF-α and IFN-γ remained unaffected.
• Immune tolerance was facilitated by tocilizumab, which selectively induced IL-10-producing CD8α+ conventional DCs and peripheral T-regulatory cells over other DC subsets.

Conclusions:

• Tocilizumab demonstrates potential in curbing excessive inflammation associated with invasive fungal infections.
• The drug's ability to modulate immune responses, promoting tolerance through specific DC and T-regulatory cell induction, offers a novel therapeutic avenue.
• Further exploration of monoclonal antibodies like tocilizumab is warranted for managing invasive fungal infections and their associated inflammatory complications.