The document summarizes a study investigating the role of regulatory T cells (Tregs) and the protein synaptotagmin 7 (Syt7) in the development of autoimmune myositis. The study found that mice lacking both Tregs and Syt7 (double knockout or DKO mice) developed more severe autoimmune myositis compared to mice with either deficiency alone. Adoptive transfer of immune cells from DKO mice into recipient mice also induced myositis. Additionally, the study identified the muscle protein myosin as a potential self-antigen that can stimulate an inflammatory response. Supplementation of Tregs was able to suppress the myositis induced by DKO immune cells, highlighting the role

1. Myosin Skews Effector
Immune Cells of Scurfy Mice
to Target Muscles in an
Adoptive Transfer Model of
Myositis
Nicholas A. Young1
, Rahul Sharma2
, Alexandra Friedman1
, Benjamin
Kaffenberger1
, Brad Bolon1
, and Wael N. Jarjour1
1
Wexner Medical Center at The Ohio State University, Columbus, Ohio
2
University of Virginia Health System, Charlottesville, VA

2. No Conflicts of Interest

3. Background
3
 Autoimmune myositis results in an inflammatory
response targeting muscle tissue
 Pathogenesis remains unclear
 Standard treatment includes non-specific
immunosuppressive therapy
Targeted therapies could be made if the disease
mechanism was better understood
 Dermatomyositis patients have reduced
Regulatory Tcell (Treg) populations
 Tregs could suppress this inflammatory
response

4. Synaptotagmin 7 (Syt7)
 Member of the synaptotagmin family of
membrane trafficking proteins
 Involved in membrane resealing
 Mutation to Syt7 causes the abnormal release of
intercellular proteins
 Syt7 knockout mice develop myositis
 Presumably due to endogenous muscle tissue
antigen exposure from “leaky” cells
• activation and expansion of autoreactive
lymphocytes
Preliminary work---Syt7

5. Preliminary work---FoxP3 knockout (scurfy mice)
are Treg deficient
 Gene product is scurfin
 X-linked gene encoding a transcription factor
imperative in the maturation and activation of
Tregs
 So these mice are Treg deficient
 Tregs suppress autoreactive cells in the
peripheral immune system
 FoxP3 knockout results in multi-organ
inflammation into a few target organs in male
mice
 No response to muscle tissue
 The mice succumb to this inflammation before
5 weeks of age
FoxP3-/y
Treg knockout
(scurfy) mouse
Forkhead box P3 (FoxP3)

6. IP transfer of autoimmune responses against multiple
organs/tissues into RAG1-/- recipients
 Not only were the target organs of the FoxP3 knockout mouse inflamed
 But 7 additional organs had an inflammatory response
 Very mild muscle tissue inflammation
 There are autoimmune lymphocytes against organs that were spared from
autoimmune attack in the FoxP3 knockout mice
 A greater repertoire of autoreactive cells exists in this mouse
 Additional preliminary data suggested that autoreactive cells to
muscle also existed
 This then served as the model for further work
Preliminary work---FoxP3 knockout adoptive
transfers into adult RAG1 -/- mice

7. Hypotheses
 Abnormal release of intracellular proteins can result in
robust autoimmune myositis when combined with the
absence of Tregs
 Tregs can suppress the pathogenesis of autoimmune
inflammation of muscle tissue
Project Goals
Design an animal model of autoimmune myositis to:
 Explore disease mechanism
 Identify possible self-antigens that could drive this
autoimmune response
 Characterize infiltrate
 Examine role of Tregs
 See if Tregs could suppress target organ inflammation

8. Analysis of inflammation
HISTOPATHOLOGY SCORING CRITERIA
Score Criteria
Skeletal Muscle: Inflammation (H&E-stained slide)
0 Within normal limits
•essentially no inflammatory cells between fibers
•any inflammatory cells are isolated, not clustered
1 Minimal
•few inflammatory cells in the fascia between fibers
•inflammatory cells are isolated or in very small clusters (< 10 cells)
2 Mild
•few inflammatory cells are located in the fascia between myofibers
•inflammatory cells typically are arranged in small clusters (15 to 25 cells)
3 Moderate
•inflammatory foci are fairly common between fibers
•inflammatory cells typically are arranged in short rows or modest clusters (30 to 45
cells)
4 Marked
•inflammatory foci are numerous
•inflammatory cells typically are arranged in long rows and large clusters (> 50 cells)
Lesion scores were assigned in a coded (“blinded”) fashion using the 10x objective

9. Analysis of inflammation

10. Syt7-/-Syt7+/-
Week
4 8 12 17+
Histopathologyscore
Ave strong intensity
IM IM
inj non-inj homogenate
CD4--Tcells 377661.2 1122126 69100
CD8--Tcells 163976.1 1027996 6252.8
F4/80--Macrophages 226820.3 702672.6 10181.8
B220--Bcells 0 0 0
SD strong intensity
IM IM
inj non-inj homogenate
CD4--Tcells 261189.3 467778.8 15308.6253
CD8--Tcells 68405.15 454180.2 2538.56078
F4/80--Macrophages 152379.5 534542 13801.8185
B220--Bcells 0 0 0
Syt7 knockout mice have mild muscle tissue
inflammation that subsides with time
*
At 4 weeks

11. Generation of double knockout (DKO) (Syt 7/FoxP3) mice
Syt7+/-
FoxP3+/y
X
FoxP3 –/y
Syt7-/-
males
Syt7+/-
Foxp3+/-
females
FoxP3 –/y
Syt7 +/-
FoxP3 +/y
Syt7 +/-
Will the absence of Tregs lead to greater muscle
tissue inflammation in Syt 7-induced myositis?
KODKO

12. FoxP3 KO Syt 7-/- DKO mouse
Treg/Syt7 double knockout (DKO) mice develop
autoimmune myositis—4weeks
supp 4wks 4wks
scurfy Treg Syt het Syt ko dko
0 1 0 2 2
1 * 1 1 3
1 * 0 2 3
1 * 0 2 2
0 * * * 3
* * * * *
* * * * *
* * * * *
* * * * *
* * * * *
0.6 1 0.25 1.75 2.6
0.547723 #DIV/0! 0.5 0.5 0.547723
0.028834
0
0.5
1
1.5
2
2.5
3
3.5
DKO
KO
DKO Ave
KO AVE
Histopathologyscore
FoxP3 KO FoxP3 KO
Syt7 -/+ Syt7 -/-
FoxP3 KO
Syt 7 -/-
FoxP3 KO
Syt 7 +/-
KO
DKO
KO DKO
*
CD3
T cells B220
B cells

13. IP Adoptive transfer into RAG1 -/- mice
Rag1 -/-
Lymph node
preparation
FoxP3 –/y
Syt7 -/-
FoxP3 –/y
Syt7 +/-
or
Can this double knockout of Syt and FoxP3
induce myositis in Rag1 mouse adoptive
transfer model?
KO
DKO

14. 0
1
2
3
4
KO
DKO
KO Ave
DKO AVE
IP
adoptive transfer
into RAG1 -/-
Histopathologyscore
Adoptive
Transfer
KO DKO
FoxP3 KO FoxP3 KO
Syt7 -/+ Syt7 -/-
FoxP3 KO
Syt 7 -/-
FoxP3 KO
Syt 7 +/-
KO
DKO
FoxP3/Syt7 double knockout adoptive transfer into
RAG1 -/- mice induces even more robust
autoimmune myositis
*

15. FoxP3/Syt7 double knockout adoptive transfer into
RAG1 -/- mice has primarily a CD4+ infiltrate
CD4--Tcells 261189.3 467778.8 15308.6253 4367.94 646067.6
CD8--Tcells 68405.15 454180.2 2538.56078 5396.437 155713.6
F4/80--Macrophages 152379.5 534542 13801.8185 688.0432 243180.2
B220--Bcells 0 0 0 0 0
0
200000
400000
600000
800000
1000000
1200000
CD4--Tcells CD8--Tcells F4/80--
Macrophages
B220--Bcells
IM-injected muscle
IM-non-injected muscle
IP+muscle tissue homogenate
IP+myosin
0
200000
400000
600000
800000
1000000
1200000
1400000
1600000
1800000
CD4--Tcells CD8--Tcells F4/80--Macrophages B220--Bcells
IM-noninjected muscle
IM-injected muscle
DKO-RAG1
0
200000
400000
600000
800000
1000000
1200000
1400000
1600000
1800000
CD4--Tcells CD8--Tcells F4/80--Macrophages B220--Bcells
FoxP3 KO
Syt 7 -/-
Pixelintensity
*
T cells
CD4
T cells
CD8
B cells
B220
Macrophage
s
F 4/80
T cells
CD4
T cells
CD8
B cells
B220
Macrophage
s
F 4/80

16. 16
WT B6
mice
IP Adoptive transfer into RAG1 -/- mice with and without muscle tissue
preparation
Will endogenous tissue antigens
induce myositis?
Rag1 -/-
Lymph node
preparation
FoxP3 –/y
Lymph node
preparation
Muscle tissue preparation
or
purified myosin protein

17. 0
1
2
3
4 IP
IP+homogenate
IP+myosin
Average
IP
IP + muscle
homogenate
IP + myosin
protein
Intracellular muscle tissue antigens can
stimulate an inflammatory response
Histopathologyscore
*
*
IP
IP + muscle
homogenate
IP + myosin
protein

18. IP+myosin
protein
T cells
CD4
T cells
CD8
B cells
B220
Macrophages
F 4/80
IP+muscle
homogenate
Pixelintensity
Pixelintensity
0
1000000
2000000
3000000
4000000
5000000
6000000
0
200000
400000
600000
800000
1000000
1200000
1400000
1600000
1800000 IP + myosin
protein
IP + muscle
homogenate
muscle antigens stimulate an inflammatory response
primarily of CD4+ cells
T cells
CD4
T cells
CD8
B cells
B220
Macrophages
F 4/80
T cells
CD4
T cells
CD8
*
*
Macrophages
F 4/80
B cells
B220

19. 19
Rag1 -/-
Lymph node
preparation
FoxP3 –/y
Syt7 -/-
Lymph node
preparation
Treg cells
Can Tregs prevent myositis in the
adoptive transfer Rag1 model?
WT
mice
IP Adoptive transfer into RAG1 -/- mice with and without purified Treg addition

20. 0
1000000
2000000
3000000
4000000
5000000
6000000
7000000
8000000
- Treg
+ Treg
Pixelintensity
Histopathology score = 1
*
Histopathology score = 3
+ Treg
- Treg
Treg supplementation suppresses inflammation induced by
Treg/Syt7 double knockout adoptive transfer into RAG1 -/- mice

21. Conclusions
 Abnormal exposure or release of intracellular proteins can cause
autoimmune myositis
 Our results indicate that myosin is at least one self-antigen that
can stimulate this response
 priming autoreactive effector T cells
 This muscle tissue infiltrate consists largely of T cells (both CD4 and
CD8)
 Few to no B cells
 This highlights the pathogenic role of CD4 cells in the disease
 Depletion of Tregs cause an inflammatory myositis
 Very mild inflammation observed in syt7 -/- mouse (which has
Tregs)
 Very robust inflammatory response seen when combined with
Treg deficiency
 Addition of Tregs can suppress this response

22. Study Implications and Future Work
 Animal models for polymyositis and dermatomyositis are
rare
 Can be used as a model to study any autoimmune
disease that involves abnormal release of cellular
protein
 Muscle tissue cells are subjected to:
 Mechanical stress
 Drug injury
 This leads to cell death, which can
contribute to abnormal release of
intracellular muscle tissue antigens
 Future investigations will focus on drug injury (statin-
induced myopathy)
22

23. Acknowledgements
23
Principal Investigator:
Dr. Wael Jarjour
Research Associate:
Alex Friedman
Medical Student Researcher:
Dr. Ben Kaffenberger
Dr. Norma Andrews:
(Synaptotagmin VII+/- females)
Collaborator:
Dr. Rahul Sharma
The Ohio State University Medical
Center, Columbus, OH
University of Virginia Health System,
Charlottesville, VA
Undergraduate Researcher:
Nitish Aggarwal
The Ohio State University
Department of Veterinary Bioscience
Veterinary Pathologist:
Dr. Brad Bolon
University of Maryland
College Park, MD

24.  Great thanks to the ACR for the invitation to speak at
the conference this year
 Questions?
24