035 Humanized anti-Desmoglein-3 antibodies as tools for research on the role of the neonatal Fc receptor in pemphigus vulgaris

Crystallographic evidence suggests that the pH-dependent affinity of IgG molecules for the neonatal Fc receptor (FcRn) receptor primarily arises from salt bridges involving IgG histidine residues, resulting in moderate affinity at mildly acidic conditions. However, this view does not explain the diversity in affinity found in IgG variants, such as the YTE mutant (M252Y,S254T,T256E), which increases affinity to FcRn by up to 10×. Here we compare hydrogen exchange measurements at pH 7.0 and pH 5.5 with and without FcRn bound with surface plasmon resonance estimates of dissociation constants and FcRn affinity chromatography. The combination of experimental results demonstrates that differences between an IgG and its cognate YTE mutant vary with their pH-sensitive dynamics prior to binding FcRn. The conformational dynamics of these two molecules are nearly indistinguishable upon binding FcRn. We present evidence that pH-induced destabilization in the CH2/3 domain interface of IgG increases binding affinity by breaking intramolecular H-bonds and increases side-chain adaptability in sites that form intermolecular contacts with FcRn. Our results provide new insights into the mechanism of pH-dependent affinity in IgG-FcRn interactions and exemplify the important and often ignored role of intrinsic conformational dynamics in a protein ligand, to dictate affinity for biologically important receptors.

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Orodigital Pemphigus Vulgaris: A Pathogenic Role of Anti-Desmoglein-3 Autoantibodies in Pemphigus Paronychia?

Dermatology ◽

10.1159/000155645 ◽

2008 ◽

Vol 217 (4) ◽

pp. 337-339 ◽

Cited By ~ 2

Author(s):

Emmanuel Laffitte ◽

Renato G. Panizzon ◽

Luca Borradori

Keyword(s):

Pemphigus Vulgaris ◽

Pathogenic Role ◽

Desmoglein 3

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Knockout of the neonatal Fc receptor in cultured podocytes alters IL-6 signaling and the actin cytoskeleton

AJP Cell Physiology ◽

10.1152/ajpcell.00235.2019 ◽

2019 ◽

Vol 317 (5) ◽

pp. C1048-C1060 ◽

Cited By ~ 2

Author(s):

Pantipa Tonsawan ◽

James Dylewski ◽

Linda Lewis ◽

Judith Blaine

Keyword(s):

Immune Complexes ◽

Fc Receptor ◽

Actin Dynamics ◽

Minimal Amount ◽

Neonatal Fc Receptor ◽

Scratch Assay ◽

Immune Mediated ◽

Actin Structure ◽

Robust Response

The neonatal Fc receptor (FcRn) has been shown to be required for antigen presentation in dendritic cells, and global knockout of FcRn attenuates immune-mediated kidney disease. Podocytes express interleukin-6 (IL-6) receptor and produce IL-6 under proinflammatory conditions. Here we examined the role of FcRn in the IL-6-mediated inflammatory response in podocytes. We examined IL-6 production by ELISA and expression by qPCR in wild type (WT) and FcRn knockout (KO) podocytes after treatment with proinflammatory stimuli as well as IL-6-mediated signaling via the JAK/STAT pathway. We also examined podocyte motility in cultured WT and KO podocytes after a proinflammatory challenge. We found that FcRn KO podocytes produced minimal amount of IL-6 after treatment with albumin, IgG, or immune complexes whereas WT podocytes had a robust response. FcRn KO podocytes also had minimal expression of IL-6 compared with WT. By Western blotting, there was significantly less phosphorylated STAT3 in KO podocytes after treatment with IFNγ or immune complexes. In a scratch assay, FcRn KO podocytes showed increased motility comparted KO, suggesting a defect in actin dynamics. Cultured FcRn KO podocytes also demonstrated abnormal stress fibers compared with WT and the defect could be rescued by IL-6 treatment. This study shows that in podocytes, FcRn modulates the IL-6 mediated response to proinflammatory stimuli and regulates podocytes actin structure, motility and synaptopodin expression.

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Differential trafficking of albumin and IgG facilitated by the neonatal Fc receptor in podocytes in vitro and in vivo.

10.1101/494823 ◽

2018 ◽

Author(s):

James Dylewski ◽

Evgenia Dobrinskikh ◽

Linda Lewis ◽

Pantipa Tonsawan ◽

Parmjit Jat ◽

...

Keyword(s):

Plasma Proteins ◽

Serum Proteins ◽

Mesangial Cells ◽

Smooth Muscle Actin ◽

Fc Receptor ◽

Neonatal Fc Receptor ◽

Kidney Disease Progression

Proteinuria is strongly associated with kidney disease progression but the mechanisms underlying podocyte handling of serum proteins such as albumin and IgG remain to be elucidated. We have previously shown that albumin and IgG are transcytosed by podocytes in vitro. In other epithelial cells, the neonatal Fc receptor (FcRn) is required to salvage albumin and IgG from the degradative pathway thereby allowing these proteins to be transcytosed or recycled. Here we directly examine the role of FcRn in albumin and IgG trafficking in podocytes by studying handling of these proteins in FcRn knockout (KO) podocytes in vitro and in a podocyte-specific FcRn knockout mice in vivo. In vitro, we find that knockout of FcRn leads to IgG accumulation in podocytes but does not alter albumin trafficking. Similarly, in vivo, podocyte-specific knockout of FcRn does not result in albumin accumulation in podocytes in vivo as measured by mean albumin fluorescence intensity whereas these mice demonstrate significant intraglomerular accumulation of IgG over time. In addition we find that podocyte-specific FcRn KO mice demonstrate mesangial expansion as they age and activation of mesangial cells as demonstrated by increased expression of ?-smooth muscle actin. Taken together, these results suggest that trafficking pathways for albumin and IgG differ in podocytes and that sustained disruption of trafficking of plasma proteins alters glomerular structure.

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Role of the Neonatal Fc Receptor for IgG in the Pathophysiology of Lupus

Case Medical Research ◽

10.31525/ct1-nct03896373 ◽

2019 ◽

Author(s):

Keyword(s):

Fc Receptor ◽

Neonatal Fc Receptor

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Th1/Th17-Related Cytokines and Chemokines and Their Implications in the Pathogenesis of Pemphigus Vulgaris

Mediators of Inflammation ◽

10.1155/2017/7151285 ◽

2017 ◽

Vol 2017 ◽

pp. 1-9 ◽

Cited By ~ 23

Author(s):

Rodolfo Pessato Timoteo ◽

Marcos Vinicius da Silva ◽

Camila Botelho Miguel ◽

Djalma Alexandre Alves Silva ◽

Jonatas Da Silva Catarino ◽

...

Keyword(s):

Immune Response ◽

Pemphigus Vulgaris ◽

Serum Levels ◽

Skin Lesions ◽

Clinical Parameters ◽

Cytokines And Chemokines ◽

Th17 Cytokines ◽

Control Disease ◽

Desmoglein 3

Pemphigus vulgaris (PV) is an autoimmune disease characterized by the presence of IgG autoantibodies against desmoglein-3. Despite the variety of findings, the chemokine and cytokine profiles that characterize the immune response in the disease are still poorly explored. Thus, 20 PV patients and 20 controls were grouped according to gender, ethnicity, place of residence, and clinical parameters of the disease. Then, the levels of chemokines and of Th1/Th2/Th17/Treg/Th9/Th22-related cytokines were assessed in the serum. PV patients had higher levels of inflammatory Th1/Th17 cytokines (IFN-γ, IL-17, and IL-23), as well as higher levels of CXCL8 and reduced levels of Th1/Th2-related chemokines (IP-10 and CCL11). However, no differences in the levels of IL-2, IL-6, TNF-α, IL-1β, IL-4, IL-9, IL-12, TGF-β, IL-33, MCP-1, RANTES, and MIP-1α were found between PV patients and their control counterparts. Furthermore, PV patients with skin lesions had higher serum levels of IL-6 and CXCL8 when compared to PV patients without lesions. Taken together, our findings describe the role of cytokines and chemokines associated with Th1/Th17 immune response in PV patients. Finally, these data are important for better understanding of the immune aspects that control disease outcome, and they may also provide important information about why patients develop autoantibodies against desmogleins.

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