Assessing cell chimerism in an acute graft-versus-host disease model established in TLR4 knockout mice

Graft-versus-host disease (GVHD) is a major complication after allogeneic hematopoietic stem cell transplantation.

To elucidate the role of Toll-like receptor 4 (TLR4), the major receptor for bacterial lipopolysaccharide, in the development of GVHD, we constructed a GVHD model in TLR4 knockout (TLR4^-/-) mice and monitored the cell chimerism.

In this study, we used polymerase chain reaction to identify whether TLR4 knockout (TLR4^-/-) mice were established. Before transplantation, we pretreated mice with irradiation so as to obtain an appropriate irradiation dose. Flow cytometry was applied to measure the chimerism status, the distributions of antigen-presenting cells (APCs), and T-cells in TLR4^+/+ and TLR4^-/- recipient mice.

The general condition of TLR4^-/- recipients was better than that of TLR4^+/+ recipients, and the TLR4^-/- recipient mice showed less severe GVHD manifestations than the TLR4^+/+ recipient mice. Most of the APCs and T-cells in the host mouse spleen were derived from donor cells, and CD4⁺ T-cells, including memory T-cells, were in the majority in host mice.

In general, our data show that TLR4 deletion attenuated GVHD development, which suggests that TLR4 could be used as a novel target and therapeutic paradigm in GVHD therapies.