monoclonal immunoglobulins in plasma cell survival Mara Victoria - - PowerPoint PPT Presentation

New animal model to study the role of monoclonal immunoglobulins in plasma cell survival

María Victoria Ayala, Sébastien Bender and Christophe Sirac

Disclosure of f Conflict of f In Interest

Nature of relationship(s)

Name of for-profit or not-for-profit

• rganization(s)

Description of relationship(s) Any direct financial payments including receipt of honoraria

Unversité de Limoges Employer

Membership on advisory boards or speakers’ bureaus Funded grants or clinical trials

Not-for-profit:

• Fondation Française pour la recherche sur

le Myélome et les gammapathies

• Ligue Contre le Cancer (France)

Research funds

Patents on a drug, product or device All other investments or relationships that could be seen by a reasonable, well- informed participant as having the potential to influence the content of the educational activity

❑ I do not have a relationship with a for-profit and/or a not-for-profit organization to disclose X I have a relationship with a for-profit and/or a not-for-profit organization to disclose

In Introduction

• Plasma cell development is closely linked to their capacity to cope with Endoplasmic

Reticulum (ER) stress during massive production of Immunoglobulins

We want to explore the direct effect of different pathogenic immunoglobulins on Plasma Cell proliferation/stress

• No mouse model available to study the toxicity induced by different immunoglobulins

in differentiated Plasma Cells

Use of B- specific promoters (CD19, CD21)

Emerging Plasma cells derive from B-cells that

• vercome the stress of

toxic immunoglobulins

Selection bias

• Abnormal Immunoglobulins can themselves be stressors and could explain the difference

in Proteasome Inhibitors sensitivity

First model of plasma cell-specific induction

CreERT2

IgJ Promoter

CreERT2

PA

Knock In (IgJ locus)

3’ Arm IgJ 5’ Arm IgJ

Only active in CD138+ cells /secreting cells

STOP

LoxP LoxP

Gene X

Oncogenes (c-MyC, Bcl2) Pathogenic Ig

CreERT2

STOP

LoxP LoxP

Gene X

STOP

LoxP LoxP

Gene X

Active CreERT2 Recombinase Cre

ERT2

T T

Tamoxifen (ERT2 agonist) Cre

ERT2

Inactive CreERT2 Recombinase

First model of plasma cell-specific induction

STOP

LoxP LoxP

Tomato

CreERT2

T

Tamoxifen (ERT2 agonist) Cre

ERT2

T

LoxP

Tomato

STOP Plasma Cell Plasma Cell + Tomato fluorescent protein IgJ-CreERT2 x Tomato Mouse

Plasma cells B cells

CH1- Mouse

+

CH2 CH3 V

Truncated Heavy Chain (CH1-)

Monoclonal Im Immunoglobulin Mouse Model

Selection bias?

CreERT2 CH1

LoxP LoxP

+

CH2 CH3 V

LoxP CH1+ Mouse IgJ-CreERT2 x

✓Check the effect of truncated HC on PC while inducing deposits formation in kidney

Heavy Chain Deposition Disease (HCDD) mouse

CD138 B220

Treated (CH1-)

Monoclonal immunoglobulin effect on PC PC

Total Spleen Cells- LPS stimulation D4

The truncated Heavy Chain generated causes a difference in stress that kills plasma cells

PC PC

B cells B cells

IgJ-CreERT2 x LoxP CH1+ Mouse

Less Plasma Cells

Death is caused by the modification of the immunoglobulin and not the production of a “novel” protein in PC: Tomato induced in differentiated PCs does not provoke death When PC develops with the truncated Heavy Chain produced from early stages there is no death: PC “selected” during B cell development to tolerate stress levels

IgJ-CreERT2 x Tomato Mouse

PC

B cells

Treated

PC

B cells

HCDD (CH1-) Mouse

Non Treated (CH1+)

Fixable Viability Stain 780 (FVS780) B220 CD138 Fixable Viability Stain 780 (FVS780)

Treated 12H Non Treated Treated 12H Non Treated Sorted PCs and B cells - LPS stimulation D3

Treated Non Treated Treated Non Treated

12H OH-Tamoxifen Treatment CH1+ CH1-

Plasma Cell Death

4-fold more dead cells

B cells Plasma Cells B cells Plasma Cells

Perspectives

• In vivo assays to validate ex vivo findings
• Analyse the precise mechanism involved in PC cell

death using the IgJ-CreERT2 x LoxP CH1+ Mouse as well as others (Light Chain Deposition Disease, Fanconi Syndrome, etc)

• Study of PC that become resistant: molecular

mechanisms and proteasome inhibitors sensitivity

Thanks for your attention!