No abstract

No abstract

Immune checkpoint blockade (ICB) therapy shows little or no clinical benefit in most colorectal cancer (CRC) patients, due to the immunosuppressive T cell contexture in the tumor microenvironment (TME). Immunoglobulin-like transcript (ILT) 4 is an immunosuppressive molecule in myeloid cells. ILT4 is enriched in solid tumor cells, facilitating their proliferation, invasion, and metastasis. However, the regulatory role of ILT4 in T cell immunity of CRC is still undetermined. Here, we aimed to explore how tumor cell-derived ILT4 orchestrates T cell infiltration, subset distribution, and function in CRC. Methods: A total of 145 paraffin-embedded cancer tissues and the corresponding clinicopathological information were collected from CRC patients. Immunohistochemical (IHC) staining and public database analyses determined the correlation of ILT4 expression with different T cell subset densities, IFN-γ levels, and patient outcomes. Paired Ig-like receptor B (PIR-B, ILT4 mouse ortholog)-overexpressing/-downregulated MC38 cells were subcutaneously injected into C57BL/6 mice as a CRC transplantation model. The frequencies, subsets, and IFN-γ levels of T cells in mouse blood and spleens were determined using flow cytometry and immunohistochemistry, respectively. Results: High ILT4 expression in CRC cells was associated with decreased T cell infiltration, disease progression, and poor patient survival. T cell subset analyses indicated that ILT4-high patients showed reduced CD8 + T cell but elevated FOXP3 + regulatory T (Treg) cell frequencies in the TME. High ILT4 levels predicted lower IFN-γ production by tumorinfiltrating lymphocytes (TILs), especially by CD8 + T cells in human CRC tissues. Moreover, PIR-B overexpression accelerated MC38 growth in mice, decreased CD3 + /CD8 + /IFN-γ + T cell densities, and elevated Treg infiltration in the TME, blood, and spleens. PIR-B knockdown had the opposite effects. Conclusion: ILT4 in CRC cells induced immunosuppressive T cell subset infiltration and impaired IFN-γ production in TILs, suggesting that ILT4 might be a potential immunotherapeutic target and prognostic biomarker.

Grain size is an important trait that directly affects grain yield in rice; however, the genetic and molecular mechanisms regulating grain size remain unclear. In this study, we identified a mutant, grain length and grain weight 10 (glw10), which exhibited significantly reduced grain length and grain weight. Histological analysis demonstrated that GLW10 affects cell expansion, which regulates grain size. MutMap-based gene mapping and transgenic experiments demonstrated that GLW10 encodes a putative brassinosteroid (BR)-signaling kinase, OsBSK2. OsBSK2 is a plasma membrane protein, and an N-myristoylation site is needed for both its membrane localization and functions. OsBSK2 directly interacts with the BR receptor kinase OsBRI1, however, genetic experiments have demonstrated that OsBSK2 likely regulates grain size independently of the BR signaling pathway. OsBSK2 can form a homodimer or heterodimers with OsBSK3 and OsBSK4, and silencing OsBSK2, OsBSK3, and OsBSK4 reduced grain size. This indicates that OsBSKs seem to function as homodimers or heterodimers to positively regulate grain size in rice. They are both highly expressed in young panicles and spikelet hulls, which indicates that they regulate grain size. In summary, our results provide novel insights into the function of BSKs in rice and novel targets for improving grain size during crop breeding.