molecular mechanisms in Heavy Chain Deposition Disease Presented by - - PowerPoint PPT Presentation

Presented by Sébastien BENDER

Contribution in the understanding of the molecular mechanisms in Heavy Chain Deposition Disease

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Name of for-profit or not-for-profit

• rganization(s)

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Heavy Chain Deposition Disease =HCDD

Molecular mechanisms of HCDD

Healthy glomerulus Sclerotic glomerulus

▪ Deposition of a truncated heavy chain (HC), mainly in the kidney. ▪ Non-organized/amorphous deposits along tubular and glomerular basement membranes. ▪ Proteinuria. ▪ Nodular glomerulosclerosis.

3

VDJ CH1 CH2 CH3

Normal 1

H

γ1 case 1

CH1 deletion is always present in HCDD

4

Molecular mechanisms of HCDD

= Binding Ig Protein

5

Molecular mechanisms of HCDD

Can CH1 deletion occur due to a problem with the light chain (LC)?

6

Molecular mechanisms of HCDD

7

Molecular mechanisms of HCDD

Identification of 2 monoclonal components

Gamma heavy chain Serum

The 2 components are produced by the same clone

@human gamma @human lambda Merge

BM

Lambda light chain BM Serum

8

Molecular mechanisms of HCDD

The lambda light chain has its V domain truncated

λmRNA atggcctgggctctgctgctcctcaccctcctcactcagggcacaggatcctgggctcagtctgccctgactcagcctccctccgtgtccgggtctcctggacagtcagtcaccatctcc Prot M A W A L L L L T L L T Q G T G S W A Q S A L T Q P P S V S G S P G Q S V T I S λmRNA tgcactggaatcagcagtgacgttggtcagcccaaggctgccccctcggtcactctgttcccaccctcctctgaggagcttcaagccaacaaggccacactggtgtgtctcataagtgac Prot C T G I S S D V G Q P K A A P S V T L F P P S S E E L Q A N K A T L V C L I S D λmRNA ttctacccgggagccgtgacagtggcctggaaggcagatagcagccccgtcaaggcgggagtggagaccaccacaccctccaaacaaagcaacaacaagtacgcggccagcagctacctg Prot F Y P G A V T V A W K A D S S P V K A G V E T T T P S K Q S N N K Y A A S S Y L λmRNA agcctgacgcctgagcagtggaagtcccacaaaagctacagctgccaggtcacgcatgaagggagcaccgtggagaagacagtggcccctacagaatgttcatag Prot S L T P E Q W K S H K S Y S C Q V T H E G S T V E K T V A P T E C S -

Leader FR1 CDR1 Cλ3 Cλ3 Cλ3

VC junction

+22nt

• 19nt

V J Cλ3 L

Protein gDNA cDNA

L V Cλ3 9

Molecular mechanisms of HCDD

CH1 deletion of the heavy chain is genomic

VDJ CH1 CH2 CH3

Normal 1

H

γ1 case 1

B C

Protein gDNA cDNA

H CH2 VDJ CH1 CH3 Sµ-Sγ1 L L VDJ H CH2 CH3 10

Molecular mechanisms of HCDD

Is the truncated LC can associate with a HC ?

F L   +     F L   c

• n

t r o l +   2 0 0 0 4 0 0 0 6 0 0 0

[ I g G  ] i n c u t u r e s u p e r n a t a n t s [IgG] in ng/mL

ND

ɣFL λcontrol Δλ ɣFL

? ?

11

Molecular mechanisms of HCDD

Is the CH1 deletion beneficial to the plasma cell ?

ɣFL Δɣ

)  (+  )  FL(+   +)  (  FL+)  ( 20 40 60 80 5 10 15 20

 HC secretion

** ns

[] intracellular/secreted [] intracellulaire/sécrété

    +         F L +   0.0 0.5 1.0 1.5 2.0 2.5

*

Stress marker Xbp1-s expression in sp2/0 clones

Relative mRNA expression

Xbp1-s

Δλ

+

OR

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Molecular mechanisms of HCDD

PROLIFERATION

Immunoglobulin

PLASMA CELL

Truncated heavy chain Truncated light chain

Oncogenics events

L VDJ CH1 H CH2 CH3 L VJλ Cλ

+

1

L VDJ CH1 H CH2 CH3 L Vλ Cλ

+

2

L VDJ H CH2 CH3 L Vλ Cλ

+

3

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Molecular mechanisms of HCDD

A new model to mimic the loss of the light chain

L VJk Ck LoxP LoxP

Light chain of Fanconi syndrome mouse model

Recombinase CRE induction

L VDJ H CH2 CH3 CH1 Ck

?

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Molecular mechanisms of HCDD

Mouse heavy chain Light chain of Fanconi syndrome mouse model (deleted)

Conclusion

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▪ We showed that deletion of the LC could be the first event leading to the generation of a truncated heavy chain in HCDD ▪ Results must be confirmed in other HCDD patients ▪ Regarding the mouse model first tests are ongoing

Thank you for your attention

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Pr Christophe Sirac Pr Arnaud Jaccard Pr Frank Bridoux Dr Vincent Javaugue Maria Victoria Ayala Amélie BONAUD Pr Guy Touchard