Preparation of anti-PD-L1 nanobodies fused with C3Fab and their effect on plasma half-life / 国际生物医学工程杂志

Objective:To prepare the anti-programmed death-ligand 1 (PD-L1) nanoantibody P3C8-C3Fab by ligating with C3Fab and to investigate its role in plasma half-life.Methods:The C3Fab peptide derived from protein G was molecularly fused with the nanobody P3C8 by DNA recombination technology. The nanoantibody P3C8-C3Fab was inducibly expressed and purified in the E. coli BL21 strain, and the binding of it to PD-L1 protein, mouse IgG, and PD-L1-expressing tumor cells was detected by enzyme-linked immunosorbent assay (ELISA). The residual P3C8-C3Fab was detected in mouse serum at different times using double-antibody sandwich ELISA to assess the prolongation of the plasma half-life of PD-L1 nanobodies by C3Fab. Results:The nanoantibody P3C8-C3Fab was successfully constructed, and it could efficiently express itself in soluble form in BL21. The purified NbP3C8-C3Fab protein was obtained with a mass fraction of about 90% at a yield of 7.18 mg/L. The affinity of P3C8-C3Fab for PD-L1 protein and mouse IgG gradually increased with increasing mass concentration and showed a concentration correlation. The binding of P3C8-C3Fab to lung cancer A549 cells showed a concentration correlation. The concentration standard curve of P3C8-C3Fab in mouse serum showed a typical S-shape with a concentration correlation. The plasma half-life of P3C8 was only 0.44 h, while the plasma half-life of P3C8-C3Fab was 21.27-fold higher, up to 9.36 h.Conclusions:The linkage of C3Fab to the nanobodies of P3C8 can significantly prolong the plasma half-life of P3C8, which is valuable for the improvement of in vivo nanobody effects.

The serum levels of FCGBP, SAA1, CXCL10 in children with mycoplasma pneumoniae pneumonia and their relationship with prognosis / 中国医师杂志

Objective:To investigate the serum levels and clinical significance of Fc fragment of the IgG-binding protein (FCGBP), serum amyloid protein A1 (SAA1), and CXC chemokine ligand 10 (CXCL10) in children with mycoplasma pneumoniae pneumonia (MPP) and their relationship with prognosis.Methods:A prospective study was conducted on 122 children with MPP admitted to the department of pediatrics of the 970th Hospital of the Joint Logistics Support Force of the Chinese People′s Liberation Army from January 2019 to December 2021. According to the severity and prognosis of MPP, they were divided into mild and severe groups, good prognosis group, and poor prognosis group. Forty healthy children who underwent physical examination during the same period were set as the control group. Enzyme-linked immunosorbent assay (ELISA) was used to detect the serum levels of FCGBP, SAA1, and CXCL10 in each subject, and to compare the differences in serum levels of FCGBP, SAA1, and CXCL10 among different groups. Multivariate logistic regression analysis was used to investigate the influencing factors of poor prognosis in MPP patients. The diagnostic value of individual and combined detection of serum procalcitonin (PCT), FCGBP, SAA1, and CXCL10 for poor prognosis in MPP children by analyzing the receiver operating characteristic (ROC) curve.Results:The levels of serum FCGBP [(115.68±10.57)ng/ml, (78.41±6.73)ng/ml, (12.55±3.25)ng/ml], SAA1 [(34.18±3.72)mg/L, (25.54±2.63)mg/L, (6.74±0.82)mg/L], and CXCL10 [(714.26±55.64)ng/L, (353.74±42.67)ng/L, (106.25±12.92)ng/L] in the severe MPP group were significant higher than those in the mild MPP group and the control group, with statistical significance (all P<0.05). The white blood cell (WBC), neutrophil percentage, C reactive protein (CRP), erythrocyte sedimentation rate (ESR), PCT, lactate dehydrogenase (LDH), D-dimer (D-D), FCGBP, SAA1, CXCL10 of the children in the poor prognosis group were significantly higher than those in the good prognosis group, and the differences were statistically significant (all P<0.05). Multivariate logistic regression analysis showed that increased PCT ( OR=1.603, 95% CI: 1.190-2.160), FCGBP ( OR=1.757, 95% CI: 1.115-2.770), SAA1 ( OR=1.900, 95% CI: 1.327-2.720) and CXCL10 ( OR=1.704, 95% CI: 1.212-2.397) were independent risk factors for poor prognosis of MPP children (all P<0.05). The combined detection of serum PCT, FCGBP, SAA1, and CXCL10 had a significantly higher diagnostic value for the risk of poor prognosis in children with MPP than a single indicator. Conclusions:The elevated levels of serum FCGBP, SAA1, and CXCL10 in children with MPP are associated with the severity of MPP and are independent risk factors for poor prognosis in MPP patients.

Proteomics study of Mycoplasma pneumoniae pneumonia reveals the Fc fragment of the IgG-binding protein as a serum biomarker and implicates potential therapeutic targets / 医学前沿

Macrolide and corticosteroid resistance has been reported in patients with Mycoplasma pneumoniae (MP) pneumonia (MPP). MP clearance is difficult to achieve through antibiotic treatment in sensitive patients with severe MPP (SMPP). SMPP in children might progress to airway remodeling and even bronchiolitis/bronchitis obliterans. Therefore, identifying serum biomarkers that indicate MPP progression and exploring new targeted drugs for SMPP treatment require urgency. In this study, serum samples were collected from patients with general MPP (GMPP) and SMPP to conduct proteomics profiling. The Fc fragment of the IgG-binding protein (FCGBP) was identified as the most promising indicator of SMPP. Biological enrichment analysis indicated uncontrolled inflammation in SMPP. ELISA results proved that the FCGBP level in patients with SMPP was substantially higher than that in patients with GMPP. Furthermore, the FCGBP levels showed a decreasing trend in patients with GMPP but the opposite trend in patients with SMPP during disease progression. Connectivity map analyses identified 25 possible targeted drugs for SMPP treatment. Among them, a mechanistic target of rapamycin kinase (mTOR) inhibitor, which is a macrolide compound and a cell proliferation inhibitor, was the most promising candidate for targeting SMPP. To our knowledge, this study was the first proteomics-based characterization of patients with SMPP and GMPP.

Biological functions of SPA-PEI conjugate as one key component for construction of a novel antibody-targeted DNA delivery system / 重庆医学

Objective To investigate the biological function of SPA-PEI conjugate(staphylococcal protein A-polyethyleneimine cross-linker),which is one key component for construction of a novel antibody-targeted DNA delivery system.Methods The binding capacity of SPA-PEI conjugate with multiple sources of IgG was determined by enzyme-linked immunosorbent assay and neutralization inhibition assay.The binding capacity of SPA-PEI conjugate with DNA fragment was determined by DNA gel retardation assay,and its DNA condensing ability was measured by Ethidium bromide exclusion assay.Results SPA-PEI conjugate could bind well to many species-derived IgGs.SPA-PEI conjugate had no significant effect on the binding properties of SPA.SPAPEI conjugate could neutralize negative charges of the plasmid DNA or DzTi.Its DNA condensing ability was nearly same to that of free PEI,which suggested a excellent DNA condensing ability of the SPA-PEI conjugate.Conclusion SPA-PEI cross-linkers prepared by this project group maintained the biological activity of SPA and PEI.SPA-PEI cross-linkers could be used for the construction of a novel antibody-targeted non-virus DNA delivery system.

Study on Fused Expression of the IgG-binding Domain of Streptococcal Protein G and Its IgG-binding Activity / 中国生物工程杂志

The IgG binding domain of Streptococcal Protein G which can selectively immobilizes the Fc regions of immunoglobulin G(IgG) is a kind of good material for oriented immobilization of antibodies in antibody microarrays.Here,genetically engineered three glutathione S-transferase(GST) fused proteins,bearing one,two and three B-Domains respectively(GST-GBx).The IgG-bindding ability of GST-GBx was investigated by ELISA.The data revealed that when the B-domain's quantity of GST-GBx is identical,the GST-GB3 is the most efficient protein among three GST-GBx protein both the capacity and sensibility of binding IgG.The GST-GB2 is the next one and GST-GB1 is the least one.Thus,the GST-GB3 has significantly predominance in comparison to GST-GB2 and GST-GB1.

Construction of the fusion protein between EGFP and IgG-binding peptide / 中国海洋药物

Objective Making the fusion protein of IgG-binding peptide with enhanced green fluorescent protein(EGFP) and determining its bioactivity.Methods The enhanced green fluorescent protein(EGFP) gene was cloned into pEZZ 18 vector containing ZZ peptide gene to construct expression vector pSpA-EGFP-His.The fusion protein was expressed in E.coliDH5? and its bioactivity was detected by competitive ELISA and fluorescence properties.Results The fusion protein migrated at approximately 42kD in SDS-PAGE,which correspond to the theoretical molecular weight.The spectra of SpA-EGFP fusion protein was similar to what was reported.SpA-EGFP competed with SpA-Peroxidase to bind IgG.Conclusion The plasmid pSpA-EGFP-His correctly expressed in E.coli.The fusion protein retains the bifunctional effects of EGFP and IgG-binding activity.