Residue substitution enhances the immunogenicity of neoepitopes from gastric cancers

Objective:Neoantigens arising from gene mutations in tumors can induce specific immune responses,and neoantigen-based immunotherapies have been tested in clinical trials.Here,we characterized the efficacy of altered neoepitopes in improving immunogenicity against gastric cancer.Methods:Raw data of whole-exome sequencing derived from a patient with gastric cancer were analyzed using bioinformatics methods to identify neoepitopes.Neoepitopes were modified by P1Y(the first amino acid was replaced by tyrosine)and P2L(the second amino acid was replaced by leucine).T2 binding and stability assays were used to detect the affinities between the neoepitopes and the HLA molecules,as well as the stabilities of complexes.Dendritic cells(DCs)presented with neoepitopes stimulated naïve CD8+T cells to induce specific cytotoxic T lymphocytes.ELISA and carboxyfluorescein succinimidyl ester were used to detect IFN-γand TNF-αlevels,and T cell proliferation.Perforin was detected by flow cytometry.The cytotoxicity of T cells was determined using the lactate dehydrogenase assay.Results:Bioinformatics analysis,T2 binding,and stability assays indicated that residue substitution increased the affinity between neoepitopes and HLA molecules,as well as the stabilities of complexes.DCs presented with altered neoepitopes stimulated CD8+T cells to release more IFN-γand had a greater effect on promoting proliferation than wild-type neoepitopes.CD8+T cells stimulated with altered neoepitopes killed more wild-type neoepitope-pulsed T2 cells than those stimulated with wild-type neoepitopes,by secreting more IFN-γ,TNF-α,and perforin.Conclusions:Altered neoepitopes exhibited greater immunogenicity than wild-type neoepitopes.Residue substitution could be used as a new strategy for immunotherapy to target neoantigens.

Kidney injury molecule-1 is a potential receptor for SARS-CoV-2

COVID-19 patients present high incidence of kidney abnormalities,which are associated with poor prognosis and mortality.The identification of SARS-CoV-2 in the kidney of COVID-19 patients suggests renal tropism of SARS-CoV-2.However,whether there is a specific target of SARS-CoV-2 in the kidney remains unclear.Herein,by using in silico simulation,coimmunoprecipitation,fluorescence resonance energy transfer,fluorescein isothiocyanate labeling,and rational design of antagonist peptides,we demonstrate that kidney injury molecule-1(KIM1),a molecule dramatically upregulated upon kidney injury,binds with the receptor-binding domain(RBD)of SARS-CoV-2 and facilitates its attachment to cell membrane,with the immunoglobulin variable Ig-like(Ig V)domain of KIM1 playing a key role in this recognition.The interaction between SARS-CoV-2 RBD and KIM1 is potently blockaded by a rationally designed KIM1-derived polypeptide AP2.In addition,our results also suggest interactions between KIM1 Ig V domain and the RBDs of SARS-CoV and MERS-CoV,pathogens of two severe infectious respiratory diseases.Together,these findings suggest KIM1 as a novel receptor for SARS-CoV-2 and other coronaviruses.We propose that KIM1 may thus mediate and exacerbate the renal infection of SARS-CoV-2 in a‘vicious cycle’,and KIM1 could be further explored as a therapeutic target.