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Phagocytosis of necrotic cells in systemic lupus erythematosus - a possible source of autoantigens?

Meftah, Layla (2013) MOBT13 20122
Degree Projects in Molecular Biology
Abstract
Abstract

Objectives: Serum from patients with systemic lupus erythematosus (SLE) is often characterized by their ability to promote phagocytosis of necrotic cell (NC) by polymorphonuclear leukocytes (PMNs). The aim of this project was to study phagocytosis of NC by PMNs in presence of serum from SLE patients, and associate the ability of phagocytosis with circulating nucleosomes and autoantibodies against different histone proteins. In addition, determine which subclasses of IgG autoantibodies SLE patients produce against the different histone proteins. Moreover, investigate if phagocytosis of NC by PMNs leads to NETosis and release of the pro-inflammatory complexes S100A8/A9. Finally, we study the variation of possible autoantigens... (More)
Abstract

Objectives: Serum from patients with systemic lupus erythematosus (SLE) is often characterized by their ability to promote phagocytosis of necrotic cell (NC) by polymorphonuclear leukocytes (PMNs). The aim of this project was to study phagocytosis of NC by PMNs in presence of serum from SLE patients, and associate the ability of phagocytosis with circulating nucleosomes and autoantibodies against different histone proteins. In addition, determine which subclasses of IgG autoantibodies SLE patients produce against the different histone proteins. Moreover, investigate if phagocytosis of NC by PMNs leads to NETosis and release of the pro-inflammatory complexes S100A8/A9. Finally, we study the variation of possible autoantigens available in apoptotic cell, necrotic cells and in NETs.
Methods: In this study 68 patient with SLE and 97 healthy individuals were included. Phagocytosis of NC by PMNs was assessed by flow cytometry. Immunoblot was used to determine the specificity and subclasses of IgG of the autoantibodies directed against histone proteins present in serum from SLE patients. ELISA was used to measure circulating nucleosomes and S100A8/A9. Proteins from apoptotic cells, necrotic cells and NETs were purified by acetone precipitation and presence of autoantibodies in serum from SLE patients against the different proteins was analyzed by immunoblot.
Results: A clear difference in phagocytosis of NC by PMNs was seen between healthy individuals and SLE patients. SLE patients were grouped according to their ability to promote phagocytosis of NC by PMNs into positive and negative patients. Phagocytosis of NC by PMNs correlated with the presence of anti-histone and anti-DNA autoantibodies as well as consumption of complement proteins and clinical manifestations involved in glomerulonephritis. All subclasses of IgG were represented in the anti-histones antibodies found in serum from SLE patients. Elevated levels of S100A8/A9 were associated to a broad spectrum of antibodies against histone proteins. The autoantibody pattern against proteins purified from apoptotic and necrotic cells resembled each other more than the autoantibody pattern against proteins purified from NETs.
Conclusion: Phagocytosis of NC by PMNs was associated with presence of autoantibodies against many different histone proteins in combination, complement consumption and disease manifestations involved in glomerulonephritis.

Popular science summary:

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by systemic inflammation in different organ system. The cause for development of autoimmunity in SLE still unclear. Serum from patients with SLE is often characterized by their ability to promote engulf of necrotic cell (NC) by polymorphonuclear leukocytes cells (PMNs). In this project, we aimed to measure engulf of NC by PMNs in presence of serum from SLE patients, and its association with nuclear material available in the patient serum and antibodies directed against different nuclear proteins. In addition, determine which type of antibodies SLE patients produce against the different nuclear proteins. Moreover, we try to look for the possible source of the proteins especially nucleus proteins that stimulate the immune system to react against the body tissues. Finally, we study the variation of possible proteins especially nucleus proteins available in different dyeing cells that stimulate the immune system. During our project, we found there was a clear difference in ability to engulf necrotic cell material by PMN between healthy persons and SLE patients. According to that, SLE patient grouped into positive and negative for ability to engulf NC. Present of antibodies directed against nuclear component important to engulf nuclear material by PMN, and consuming of serum complement proteins seem to play important role during that process. SLE patient serum showed different type of antibodies that produce against the different nuclear proteins. All different kind of dying cell in the body was possible source for proteins that stimulate the immune system to react against the body, with some variation.

Advisors: Anders Bengtsson/Birgitta Gullstrand
Master´s Degree Project in Immunology, 60 credits
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Meftah, Layla
supervisor
organization
course
MOBT13 20122
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
3910707
date added to LUP
2013-06-27 10:54:25
date last changed
2013-06-27 10:54:25
@misc{3910707,
  abstract     = {Abstract 

Objectives: Serum from patients with systemic lupus erythematosus (SLE) is often characterized by their ability to promote phagocytosis of necrotic cell (NC) by polymorphonuclear leukocytes (PMNs). The aim of this project was to study phagocytosis of NC by PMNs in presence of serum from SLE patients, and associate the ability of phagocytosis with circulating nucleosomes and autoantibodies against different histone proteins. In addition, determine which subclasses of IgG autoantibodies SLE patients produce against the different histone proteins. Moreover, investigate if phagocytosis of NC by PMNs leads to NETosis and release of the pro-inflammatory complexes S100A8/A9. Finally, we study the variation of possible autoantigens available in apoptotic cell, necrotic cells and in NETs. 
Methods: In this study 68 patient with SLE and 97 healthy individuals were included. Phagocytosis of NC by PMNs was assessed by flow cytometry. Immunoblot was used to determine the specificity and subclasses of IgG of the autoantibodies directed against histone proteins present in serum from SLE patients. ELISA was used to measure circulating nucleosomes and S100A8/A9. Proteins from apoptotic cells, necrotic cells and NETs were purified by acetone precipitation and presence of autoantibodies in serum from SLE patients against the different proteins was analyzed by immunoblot. 
Results: A clear difference in phagocytosis of NC by PMNs was seen between healthy individuals and SLE patients. SLE patients were grouped according to their ability to promote phagocytosis of NC by PMNs into positive and negative patients. Phagocytosis of NC by PMNs correlated with the presence of anti-histone and anti-DNA autoantibodies as well as consumption of complement proteins and clinical manifestations involved in glomerulonephritis. All subclasses of IgG were represented in the anti-histones antibodies found in serum from SLE patients. Elevated levels of S100A8/A9 were associated to a broad spectrum of antibodies against histone proteins. The autoantibody pattern against proteins purified from apoptotic and necrotic cells resembled each other more than the autoantibody pattern against proteins purified from NETs. 
Conclusion: Phagocytosis of NC by PMNs was associated with presence of autoantibodies against many different histone proteins in combination, complement consumption and disease manifestations involved in glomerulonephritis.

Popular science summary:

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by systemic inflammation in different organ system. The cause for development of autoimmunity in SLE still unclear. Serum from patients with SLE is often characterized by their ability to promote engulf of necrotic cell (NC) by polymorphonuclear leukocytes cells (PMNs). In this project, we aimed to measure engulf of NC by PMNs in presence of serum from SLE patients, and its association with nuclear material available in the patient serum and antibodies directed against different nuclear proteins. In addition, determine which type of antibodies SLE patients produce against the different nuclear proteins. Moreover, we try to look for the possible source of the proteins especially nucleus proteins that stimulate the immune system to react against the body tissues. Finally, we study the variation of possible proteins especially nucleus proteins available in different dyeing cells that stimulate the immune system. During our project, we found there was a clear difference in ability to engulf necrotic cell material by PMN between healthy persons and SLE patients. According to that, SLE patient grouped into positive and negative for ability to engulf NC. Present of antibodies directed against nuclear component important to engulf nuclear material by PMN, and consuming of serum complement proteins seem to play important role during that process. SLE patient serum showed different type of antibodies that produce against the different nuclear proteins. All different kind of dying cell in the body was possible source for proteins that stimulate the immune system to react against the body, with some variation.

Advisors: Anders Bengtsson/Birgitta Gullstrand
Master´s Degree Project in Immunology, 60 credits
Department of Biology, Lund University},
  author       = {Meftah, Layla},
  language     = {eng},
  note         = {Student Paper},
  title        = {Phagocytosis of necrotic cells in systemic lupus erythematosus - a possible source of autoantigens?},
  year         = {2013},
}