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Pparg-Cre.Csf1r-LSL-DTR-mCherry - A new model to study macrophages and monocytes

Markström, Elise (2017) MOBN01 20171
Degree Projects in Molecular Biology
Abstract
Macrophages are innate immune cells involved in tissue homeostasis and immunity. They are phagocytes and provide the first line of defense to invading pathogens. Tumors are abundantly populated with macrophages and they are also involved in many autoimmune diseases. Since macrophages play a crucial role in homoeostasis and disease they have emerged as key therapeutic target. However, to manipulate them it is essential to have in depth understanding of their origin and function.
Here we describe a newly generated mouse line, that requires both the expression of Pparg and Csf1r to label and deplete macrophages via mCherry and DTR expression, respectively. The transcription factor peroxisome proliferator activated receptor gamma (PPARγ)... (More)
Macrophages are innate immune cells involved in tissue homeostasis and immunity. They are phagocytes and provide the first line of defense to invading pathogens. Tumors are abundantly populated with macrophages and they are also involved in many autoimmune diseases. Since macrophages play a crucial role in homoeostasis and disease they have emerged as key therapeutic target. However, to manipulate them it is essential to have in depth understanding of their origin and function.
Here we describe a newly generated mouse line, that requires both the expression of Pparg and Csf1r to label and deplete macrophages via mCherry and DTR expression, respectively. The transcription factor peroxisome proliferator activated receptor gamma (PPARγ) contribution to the development and polarization of spleen and alveolar macrophages, and the colony-stimulating factor 1 receptor (CSF1R) is the major lineage regulator of macrophages which once bound by its ligand stimulates survival and proliferation. This mouse model is an improved model for monocytes as it labels all monocytes as well as its progenitors, MDPs and cMoPs. This model is however not entirely specific for macrophages and monocytes since it also labels granulocytes and DCs. Based on the mouse model, we also characterized a more mature subset of bone marrow Ly6C- monocytes. (Less)
Popular Abstract
A new model to study macrophages

Macrophages are specialized immune cells that protects us against infection by “eating” or engulfing pathogens in a process called phagocytosis. They are also in charge of engulfing the body’s own cellular debris and dead cells. Researchers have linked malfunctions in taking care of the dead cells to autoimmune diseases. Autoimmune diseases, such as multiple sclerosis and Crohn’s disease, arise when the immune system attacks the body’s own cells or cellular debris, instead of foreign intruders such as bacteria and viruses. Furthermore, macrophages are present in tumors where they can promote tumor growth and suppress antitumor immunity. Since macrophages play a crucial role in maintaining a healthy body... (More)
A new model to study macrophages

Macrophages are specialized immune cells that protects us against infection by “eating” or engulfing pathogens in a process called phagocytosis. They are also in charge of engulfing the body’s own cellular debris and dead cells. Researchers have linked malfunctions in taking care of the dead cells to autoimmune diseases. Autoimmune diseases, such as multiple sclerosis and Crohn’s disease, arise when the immune system attacks the body’s own cells or cellular debris, instead of foreign intruders such as bacteria and viruses. Furthermore, macrophages are present in tumors where they can promote tumor growth and suppress antitumor immunity. Since macrophages play a crucial role in maintaining a healthy body as well as in disease they are emerging as therapeutic targets. However, in order to manipulate them it is essential to have an in depth understanding of their origin and function, two processes that are still not completely understood.

In this thesis, we have studied the origin and function of macrophages using a newly generated mouse line. The aim of the new line was to specifically tag and delete macrophages. To do so, two transgenes; one encoding for a red fluorescent protein and one for the diphtheria toxin receptor (DTR), were expressed under the control of two macrophage-specific genes. The red fluorescent protein allowed the visualisation of the tagged cells using a technique called flow cytometry. The DTR is not normally expressed in mice and binds diphtheria toxin (DT) produced by Corynebacterium diphtheria. When DT is injected into these transgenic mice, the cells expressing DTR are killed. This gives us the opportunity to analyse the effect a loss of macrophages has on disease and the maintenance of a healthy body.

Similar models have been tested before, but the crucial part of limiting transgene expression to macrophages has so far been insufficient. Here we show that the combination of two macrophage-specific genes used to tag macrophages, labels macrophages in many organs, while other immune cells such as T cell were not labelled. However, immune cells closely related to macrophages such as granulocytes and DC were also tagged in our new mouse model. Deletion of the macrophages by DT injection was highly efficient in the new mouse line, although further experiments are needed to evaluate the effect DT has on other cell types.


Master’s Degree Project in Molecular Biology, 45 credits 2017
Department of Biology, Lund University
German Cancer Research Centre (DKFZ), Heidelberg, Germany

Advisor: Markus Feuerer
Helmholtz University Junior Research Group Immune Tolerance, DKFZ, Heidelberg, Germany (Less)
Please use this url to cite or link to this publication:
author
Markström, Elise
supervisor
organization
course
MOBN01 20171
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
8925106
date added to LUP
2017-09-08 14:53:20
date last changed
2017-09-08 14:53:20
@misc{8925106,
  abstract     = {Macrophages are innate immune cells involved in tissue homeostasis and immunity. They are phagocytes and provide the first line of defense to invading pathogens. Tumors are abundantly populated with macrophages and they are also involved in many autoimmune diseases. Since macrophages play a crucial role in homoeostasis and disease they have emerged as key therapeutic target. However, to manipulate them it is essential to have in depth understanding of their origin and function.
Here we describe a newly generated mouse line, that requires both the expression of Pparg and Csf1r to label and deplete macrophages via mCherry and DTR expression, respectively. The transcription factor peroxisome proliferator activated receptor gamma (PPARγ) contribution to the development and polarization of spleen and alveolar macrophages, and the colony-stimulating factor 1 receptor (CSF1R) is the major lineage regulator of macrophages which once bound by its ligand stimulates survival and proliferation. This mouse model is an improved model for monocytes as it labels all monocytes as well as its progenitors, MDPs and cMoPs. This model is however not entirely specific for macrophages and monocytes since it also labels granulocytes and DCs. Based on the mouse model, we also characterized a more mature subset of bone marrow Ly6C- monocytes.},
  author       = {Markström, Elise},
  language     = {eng},
  note         = {Student Paper},
  title        = {Pparg-Cre.Csf1r-LSL-DTR-mCherry - A new model to study macrophages and monocytes},
  year         = {2017},
}