Intranasal booster drives class switching and homing of memory B cells for mucosal IgA response
Si Chen, Zhengyuan Zhang, Zihan Lin, Li Yin, Lishan Ning, Wenming Liu, Qian Wang, Chenchen Yang, Bo Feng, Ying Feng, Yongping Wang, Hengchun Li, Ping He, Huan Liang, Yichu Liu, Zhixia Li, Bo Liu, Yang Li, Diana Boraschi, Linbing Qu, Xuefeng Niu, Nanshan Zhong, Pingchao Li, Ling Chen
Si Chen, Zhengyuan Zhang, Zihan Lin, Li Yin, Lishan Ning, Wenming Liu, Qian Wang, Chenchen Yang, Bo Feng, Ying Feng, Yongping Wang, Hengchun Li, Ping He, Huan Liang, Yichu Liu, Zhixia Li, Bo Liu, Yang Li, Diana Boraschi, Linbing Qu, Xuefeng Niu, Nanshan Zhong, Pingchao Li, Ling Chen
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Research Article Immunology Infectious disease Public Health

Intranasal booster drives class switching and homing of memory B cells for mucosal IgA response

Abstract

Mucosal secretory IgA (sIgA) plays a central role in protecting against the invasion of respiratory pathogen via the upper respiratory tract. To understand how intranasal booster induces mucosal sIgA response in humans, we first used liquid chromatography–tandem mass spectrometry for peptide identification of immunoglobulin (MS Ig-seq) and single-cell B cell receptor sequencing (scBCR-seq) to identify 42 mucosal spike-specific sIgA monoclonal antibodies (mAbs) after intranasal booster. These mucosal sIgA mAbs exhibited enhanced neutralization up to 100-fold against SARS-CoV-2 variants compared with their monomeric IgG and IgA isotypes. Deep sequencing and longitudinal analysis of B cell receptor repertoires revealed that intranasal booster restimulates memory B cells primed by intramuscular vaccination to undergo IgA class switching, somatic hypermutation, and clonal expansion. Single-cell RNA-seq (scRNA-seq) revealed that intranasal booster upregulated the expression of mucosal homing receptors in spike-specific IgA-expressing B cells. This increase coincided with a transient increase of cytokines and chemokines that facilitate B cell recruitment in the nasal mucosa. Our findings demonstrate that intranasal booster can be an effective strategy for inducing upper respiratory mucosal sIgA and establishing mucosal immune protection.

Authors

Si Chen, Zhengyuan Zhang, Zihan Lin, Li Yin, Lishan Ning, Wenming Liu, Qian Wang, Chenchen Yang, Bo Feng, Ying Feng, Yongping Wang, Hengchun Li, Ping He, Huan Liang, Yichu Liu, Zhixia Li, Bo Liu, Yang Li, Diana Boraschi, Linbing Qu, Xuefeng Niu, Nanshan Zhong, Pingchao Li, Ling Chen

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Figure 2

Identification of mucosal sIgA mAbs using MS Ig-seq and scBCR-seq.

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Identification of mucosal sIgA mAbs using MS Ig-seq and scBCR-seq. (A) S...
(A) Scheme of the study. The schematic was drawn using BioRender. For MS Ig-seq, BA.1 spike-specific sIgA from a donor was isolated using magnetic beads coupled with BA.1 spike, digested with trypsin, and analyzed using LC-MS/MS. A personalized antibody repertoire was constructed by scBCR-seq from the same donor. cDNAs encoding the heavy chain and light chain of respective antibodies were synthesized and cloned into expression plasmids. (B) The germline heavy- and light-chain gene usage (IGHV, IGKV, and IGLV) and their pairing combinations among the 45 isolated antibodies were visualized using a chord diagram. Each arc represents a heavy-chain and light-chain germline gene pair, the width of which is proportional to the corresponding antibody count. (C) Binding of mucosal mAbs (719-1 to 45, IgG) to variant spike proteins (BA.1, BA.5, XBB.1.5, and JN.1) was measured by ELISA. The chart shows mAbs with EC50 below 5 nM against at least 2 variants. (D) BLI-based competition assays were performed between RBD-binding mAbs 719-1, 719-14, 719-37, 719-40, 719-42, and known antibodies targeting distinct RBD epitopes (LY-CoV-555, P2B-2F6, FC08, S309 and CR3022) or ACE2. The competition percent between each isolated mAb and the known antibodies or ACE2 is presented in the table. (E) Assessment of the neutralizing potency of mAbs 719-1, 719-3, 719-4, 719-14, 719-19, 719-37, 719-39, 719-40, and 719-42 expressed in IgG, mIgA, dIgA, and sIgA forms against pseudoviruses expressing spike from WT and Omicron subvariants BA.1, BA.5, XBB.1.5, JN.1, and KP.3. Data are shown as IC50.