Javier Orozco-Cordoba

Mexico

Trim33 regulates TH9 differentiation and in vivo function.

Javier Orozco-Cordoba1, Eugenio Contreras-Castillo1, Ofelia Muñoz-Paleta1, Daniel Zambrano-Romero1, Jose Luis Ramos-Balderas1, Paula Licona-Limon1

1. Instituto de Fisiologia Celular, UNAM.

Abstract

Background

The TGF-β signaling pathway has been extensively studied in CD4+ T cells, particularly in TH17, Treg, and, more recently in TH9 cells, characterized by high IL-9 production and its dependency on TGF-β and IL-4 for their generation. The canonical TGF-β pathway is regulated by Smad2/3 and Smad4; however, non-canonical TGF-β pathways in TH9 remain unknown. In this work, we dilucidated the role of the alternative TGF-β pathway regulated by Trim33, an E3 Ubiquitin ligase and double epigenetic reader, which was underexplored in Th9 cells.

Methods

By using a conditional knockout mouse model for Trim33 (CD4-Cre) in the IL-9, IL-4 and FOXP3 reporter background, we evaluated the effect of Trim33’s absence by measuring in vitro differentiation and Th9 in vivo function during helminth infection and melanoma models.

Results

We demonstrated that Trim33 plays a crucial role during cell commitment to the Th9 lineage by inhibiting IL-9 expression and cell proliferation in vitro. While, during helminth infection with Nippostrongylus brasiliensis, Trim33 negatively regulates TH9 differentiation and effector function, thus modulating ILCs and Mast cell function and expansion. Furthermore, in a B16 melanoma model, we found an enhanced antitumor response in Trim33-deficient mice, led by an increment of TH9 cells within the tumor and lymph nodes. Mechanistically, Trim33 also modulates IL-4 signaling, as Trim33-deficient cells exhibit heightened IL-4 sensitivity and higher expression of STAT6 and IRF4. On the other hand, we demonstrated in these inflammatory contexts the generation of TH9-like Treg cells, a poorly described population characterized by the concomitant expression of IL-9 and FOXP3, and the acquisition of exhausting markers, however, the biological relevance of this population is still unknown.

Conclusions

Collectively, our data indicates that Trim33 is a crucial molecule in the differentiation and function of TH9 lymphocytes, highlighting its potential as a therapeutic target in diseases where TH9 cells play a central role, while with TH9-like Treg, we open the venue to evaluate its biological role within these diseases.