Evaluation of antibody-dependent cell-mediatedcy totoxicity activity and cetuximab response in KRAS wildtype metastatic colorectal cancer patients

AIM:To investigate the prognostic role of invariant natural killer T(iNKT) cells and antibody-dependent cell-mediated cytotoxicity(ADCC) in wild type KRAS metastatic colorectal cancer(mC RC) patients treated with cetuximab.METHODS: Forty-one KRAS wt mC RC patients,treated with cetuximab and irinotecan-based chemotherapy in Ⅱ and Ⅲ lines were analyzed. Genotyping of single nucleotide polymorphism(SNP)s in the FCGR2A,FCGR3A and in the 3' untranslated regions of KRAS and mutational analysis for KRAS,BRAF and NRAS genes was determined either by sequencing or allelic discrimination assays. Enriched NK cells were obtained from lymphoprepperipheral blood mononuclear cell and iN KT cells were defined by co-expression of CD3,TCRVα24,TCRVβ11. ADCC was evaluated as ex vivo NK-dependent activity,measuring lactate dehydrogenase release.RESULTS: At basal,mCRC patients performing ADCC activity above the median level(71%) showed an improved overall survival(OS) compared to patients with ADCC below(median 16 vs 8 mo;P=0.026). We did not find any significant correlation of iN KT cells with OS(P=0.19),albeit we observed a trend to a longer survival after 10 mo in patients with iN KT above median basal level(0.382 cells/microliter). Correlation of OS and progression-free survival(PFS) with interesting SNPs involved in ADCC ability revealed not to be significant. Patients carrying alleles both with A in FCGR2 A and TT in FCGR3A presented a trend of longer PFS(median 9 vs 5 mo;P=0.064). Chemotherapy impacted both iN KT cells and ADCC activity. Their prognostic values get lost when we analysed them after 2 and 4 mo of treatment.CONCLUSION: Our results suggest a link between iN KT cells,basal ADCC activity,genotypes in FCGR2A and FCGR3A,and efficacy of cetuximab in KRAS wt mC RC patients.

Anti-PD-L1 antibody enhances curative effect of cryoablation via antibody-dependent cell-mediated cytotoxicity mediating PD-L1^(high)CD11b^(+)cells elimination in hepatocellular carcinoma

Cryoablation(CRA)and microwave ablation(MWA)are two main local treatments for hepatocellular carcinoma(HCC).However,which one is more curative and suitable for combining with immunotherapy is still controversial.Herein,CRA induced higher tumoral PD-L1 expression and more T cells infiltration,but less PD-L1^(high)CD11b^(+)myeloid cells infiltration than MWA in HCC.Furthermore,CRA had better curative effect than MWA for anti-PD-L1 combination therapy in mouse models.Mechanistically,anti-PD-L1 antibody facilitated infiltration of CD8^(+)T cells by enhancing the secretion of CXCL9 from cDC1 cells after CRA therapy.On the other hand,anti-PD-L1 antibody promoted the infiltration of NK cells to eliminate PD-L1^(high)CD11b^(+)myeloid cells by antibody-dependent cell-mediated cytotoxicity(ADCC)effect after CRA therapy.Both aspects relieved the immunosuppressive microenvironment after CRA therapy.Notably,the wild-type PD-L1 Avelumab(Bavencio),compared to the mutant PD-L1 atezolizumab(Tecentriq),was better at inducing the ADCC effect to target PD-L1^(high)CD11b^(+)myeloid cells.Collectively,our study uncovered the novel insights that CRA showed superior curative effect than MWA in combining with anti-PD-L1 antibody by strengthening CTL/NK cell immune responses,which provided a strong rationale for combining CRA and PD-L1 blockade in the clinical treatment for HCC.

Potential of Antibody-Dependent Cellular Cytotoxicity in Acute and Recovery Phases of SARS-CoV-2 Infection

Background:Severe acute respiratory syndrome coronavirus-2(SARS-CoV-2)has caused a global pandemic that has resulted in millions of casualties.Although researchers have reported the existence of neutralizing antibodies and viral T cell immunity against SARS-CoV-2,little is known about the presence of antibody-dependent cellular cytotoxicity(ADCC)and its role in combating SARS-CoV-2 infection.Methods:Nineteen acute COVID-19 patients at the First Affiliated Hospital of Guangzhou Medical University from January to February,2020 and 55 recovery COVID-19 patients at the Second Peoples Hospital of Changde City from February,2020 to February,2021 were recruited in this study.Longitudinal plasma samples were collected.A virus-specific ADCC assay was performed to study the COVID-19 plasma samples.The correlations between ADCC and total IgG titer,including anti-RBD,anti-N,and neutralizing antibody titer were analyzed.Results:A high level of ADCC with 0.86%of IFN-g+CD107a+NK cells induced by anti RBD antibodies and with 0.54%of IFN-g+CD107a+NK cells induced by anti N antibodies was observed.This activity peaked at 3 weeks after disease onset with 1.16%and 0.63%of IFN-g+CD107a+NK cells induced by anti RBD and anti N antibodies respectively,declined to 0.32%and 0.32%of IFN-g+CD107a+NK cells respectively after more than 2 months,and persisted for 12 months after disease onset.The ADCC did not aggravate the severity of COVID-19 in terms of sequential organ failure assessment,although ADCC decreased with the age of COVID-19 patients.Interestingly,ADCC response is not correlated with neutralizing antibody titer or total IgG titers against S protein RBD and N protein in acute patients.ADCC in recovered patients showed a significant correlation with anti RBD IgG titer(R2=0.33,P<0.001).Conclusion:Antibodies from COVID-19 patients against the N protein and S protein RBD domains could stimulate high levels of ADCC response.Our results provide evidence that vaccination should not only focus on neutralizing antibodies but also binding antibodies that may facilitate the antiviral function of ADCC,especially in the elderly.

A novel method to assess antibody-dependent cell-mediated cytotoxicity against influenza A virus M2 in immunized murine models

The matrix protein 2 (M2) is a preferred target for developing a universal vaccine against the influenza A virus (IAV). This study aimed to develop a method for assessing antibody-dependent cell-mediated cytotoxicity (ADCC) associated with M2-based immunization in mice. We first established a stable cell line derived from mouse lymphoma cells (YAC-1) expressing M2 of H3N2. This cell line, designated as YAC-1-M2, was generated using a second-generation lentiviral tricistronic plasmid system to transduce the M2 gene into YAC-1 cells. The ADCC effect induced by polyclonal antibodies targeting matrix protein 2 ectodomain (M2e) was demonstrated by YAC-1-M2 cell lysis by natural killer cells (NK) derived from mice, in the presence of anti-M2 antibodies obtained from mice immunized with an mRNA vaccine based on M2e. This ADCC effect was found to be stronger compared to the effect induced by monoclonal antibodies (14C2) against M2. Moreover, the ADCC effect was enhanced as the effector-to-target ratio of NK to YAC-1-M2 cells increased. In conclusion, we established a novel method to detect ADCC of M2 of IAV, which paves the way for the development of an M2-based universal vaccine against IAV and an in-depth analysis of its mechanism of broad-spectrum immune protection in mice.

The Effect of Tremella Fuciformis Spores Polysaccharides (TSP) on Immune Cellular Function of Mice in Vitro

TSP could markedly enhance the proliferative response of the murine splenocyte to LPS and induce the mitogenesis of the spleen cells.Furthermore,it was able to augment the activity of natural killer cell and ADGG;at a dosage of 25-250μg/ml,the ability of splenocytes to produce IL-2 induced by onA had been improved; at the concentration of 250μg／ml or more,TSP could inhibit the proliferative response of the murine lymphocyte to GonA and the ~3-HTdR spontaneous incorporation rate of thymocytes,and the inhibitory action ran in paralell with the increase in concentration of TSP.

Novel Strategies for Redirecting NK Cells in Cancer Immunotherapy

Natural killer(NK)cells act as a first line of defense in innate immune system against new malignant transformed cells without prior exposure to tumor antigens.The activity of NK cells is tightly controlled by a balance between inhibitory receptors and activating receptors,and when activation signals outweigh inhibitory signals,NK cells can mediate a response to eliminate the targeted cells.As a bridge between the innate and adaptive immune responses to enhance destruction of tumors,NK cells kill their tumor targets through a variety of mechanisms,including receptor-mediated cytotoxicity,antibody-dependent cell-mediated cytotoxicity(ADCC),death receptor Fas/FasL signaling pathway-mediated cancer apoptosis.However,the efficacy of using NK cells for tumor immunotherapy has been limited by a lack of antigen specificity.To overcome this limitation,Vallera and colleagues developed a bispecific killer cell engager(BiKE),which is comprised of a first ScFv that recognizes a tumor antigen and a second ScFv against CD16(expressed on NK cells)to trigger ADCC.To overcome the poor expansion of NK cells in vivo,a novel trispecific killer cell engager(TriKE)was evolved from the BiKE by the same team.In this molecule,IL-15 was integrated to promote NK cell expansion,thereby eliciting superior NK cytotoxicity and NK cell persistence in vivo compared to BiKE.In order to simultaneously target drug-refractory cancer stem cells(CSC)and cancer cells,a novel tetraspecific killer engager(TetraKE)comprising anti-CD133,EpCAM,CD16 ScFvs and a sustaining IL-15 signal cross-linker was recently developed.Compared to BiKE or TriKE,TetraKE1615EpCAM133 was highly specific against EpCAM-and CD133-bearing cells,leading to enhanced NK cell proliferation,prolonged survival and a limited cytokine response.This TetraKE represents a promising new modality for immunotherapy.

Electrophoretic Analysis on RNA of Deltamethrin－resistant Culex Pipiens Pallens

TSP could markedly enhance the proliferative response of the murine splenocyte to LPS and induce the mitogenesis of the spleen cells.Furthermore,it was able to augment the activity of natural killer cell and ADGG;at a dosage of 25-250μg/ml,the ability of splenocytes to produce IL-2 induced by onA had been improved; at the concentration of 250μg/ml or more,TSP could inhibit the proliferative response of the murine lymphocyte to GonA and the ￣3-HTdR spontaneous incorporation rate of thymocytes,and the inhibitory action ran in paralell with the increase in concentration of TSP.

Promotion of cell proliferation and inhibition of ADCC by cancerous immunoglobulin expressed in cancer cell lines

To explore the significance of cancerous immunoglobulin(Ig)in cancer cell growth,HeLa cervical cancer cells were stably transfected with small interfering RNA(siRNA)that specifically,efficiently and consistently silences the expression of heavy chain genes of all immunoglobulin isotypes.This stable cell line was used to examine cell viability,colony formation and tumor growth in athymic nude mice.The results of these experiments indicated that siRNA-mediated knockdown of cancerous Ig inhibited cell growth in vitro and suppressed tumor cell growth in immune-deficient nude mice in vivo.Similarly,this siRNA also inhibited the growth of MGC gastric cancer cells and MCF-7 breast cancer cells.Furthermore,the presence of cancerous Ig specifically reduced antibody-dependent cell-mediated cytotoxicity(ADCC)induced by an anti-human epithelial growth factor receptor(EGFR)antibody in a dose-dependent manner,suggesting that the cancerous Ig-Fc receptor interaction inhibits natural killer cell(or NK cell)effector function.The prevalent expression of Ig in human carcinomas and its capacity to promote growth and inhibit immunity might have important implications in growth regulation and targeted therapy for human cancers.