Proteasome inhibition reduces plasma cell and antibody secretion, but not angiotensin II-induced hypertension

Hericka Bruna Figueiredo Galvao; Quynh Nhu Dinh; Jordyn M Thomas; Flavia Wassef; Henry Diep; Alex Bobik; Christopher G Sobey; Grant R Drummond; Antony Vinh

doi:10.3389/fcvm.2023.1184982

Proteasome inhibition reduces plasma cell and antibody secretion, but not angiotensin II-induced hypertension

Front Cardiovasc Med. 2023 Jun 2:10:1184982. doi: 10.3389/fcvm.2023.1184982. eCollection 2023.

Authors

Hericka Bruna Figueiredo Galvao¹, Quynh Nhu Dinh¹, Jordyn M Thomas², Flavia Wassef¹, Henry Diep¹, Alex Bobik^{3

4

5}, Christopher G Sobey^{1

3}, Grant R Drummond^#^{1

3}, Antony Vinh^#¹

Affiliations

¹ Department of Microbiology, Anatomy, Physiology and Pharmacology, Centre for Cardiovascular Biology and Disease Research, School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, VIC, Australia.
² Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia.
³ Baker Heart and Diabetes Institute, Prahran, Australia.
⁴ Department of Immunology, Monash University, Melbourne, VIC, Australia.
⁵ Centre for Inflammatory Diseases, Monash University, Clayton, VIC, Australia.

^# Contributed equally.

Abstract

Introduction: Depletion of mature B cells affords protection against experimental hypertension. However, whether B cell-mediated hypertension is dependent on differentiation into antibody-secreting cells (ASCs) remains unclear. Using the proteasome inhibitor, bortezomib, the present study tested the effect of ASC reduction on angiotensin II-induced hypertension.

Methods: Male C57BL6/J mice were infused with angiotensin II (0.7 mg/kg/day; s.c.) for 28 days via osmotic minipump to induce hypertension. Normotensive control mice received saline infusion. Bortezomib (750 μg/kg) or vehicle (0.1% DMSO) was administered (i.v.) 3 days prior to minipump implantation, and twice weekly thereafter. Systolic blood pressure was measured weekly using tail-cuff plethysmography. Spleen and bone marrow B1 (CD19⁺B220^-), B2 (B220⁺CD19⁺) and ASCs (CD138^hiSca-1⁺Blimp-1⁺) were enumerated by flow cytometry. Serum immunoglobulins were quantified using a bead-based immunoassay.

Results: Bortezomib treatment reduced splenic ASCs by ∼68% and ∼64% compared to vehicle treatment in normotensive (2.00 ± 0.30 vs. 0.64 ± 0.15 × 10⁵ cells; n = 10-11) and hypertensive mice (0.52 ± 0.11 vs. 0.14 ± 0.02 × 10⁵ cells; n = 9-11), respectively. Bone marrow ASCs were also reduced by bortezomib in both normotensive (4.75 ± 1.53 vs. 1.71 ± 0.41 × 10³ cells; n = 9-11) and hypertensive mice (4.12 ± 0.82 vs. 0.89 ± 0.18 × 10³ cells; n = 9-11). Consistent with ASC reductions, bortezomib reduced serum IgM and IgG2a in all mice. Despite these reductions in ASCs and antibody levels, bortezomib did not affect angiotensin II-induced hypertension over 28 days (vehicle: 182 ± 4 mmHg vs. bortezomib: 177 ± 7 mmHg; n = 9-11).

Conclusion: Reductions in ASCs and circulating IgG2a and IgM did not ameliorate experimental hypertension, suggesting other immunoglobulin isotypes or B cell effector functions may promote angiotensin II-induced hypertension.

Keywords: angiotensin II; antibody secreting cells; bortezomib; hypertension; immunoglobulins; plasma cells; proteasome inhibition.

Grants and funding

NHMRC Project Grant GNT1144243.