Disclosures. Pathogenesis of Autoimmunity Normal immune response: 11/5/2011. Methotrexate and JUN Pathway Activation in Rheumatoid Arthritis

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1 Methotrexate and JUN Pathway Activation in Rheumatoid Arthritis Disclosures N. Olsen and T. Aune are co-founders of ArthroChip LLC. Nancy J. Olsen Penn State MS Hershey Medical Center Thomas M. Aune Vanderbilt University Medical Center Pathogenesis of Autoimmunity Normal immune response: General recognition of danger by the innate immune system. Specific recognition of foreign antigen by the adaptive immune system. Autoimmune response: Breach in self-tolerance. Self recognized as foreign by the adaptive immune system. Renoir Pathogenesis of RA: Is danger from without or within? Exogenous: infectious agents, environmental exposures or Endogenous: internal or intracellular components. BACKGROUND: How did we get here? 1

2 Peripheral Blood Gene Expression Patterns in Autoimmune Disease A set of downregulated genes in autoimmune disease patients (gray bars) vs. normal subjects (black bars). The autoimmune group included RA patients, and p53 was one of the downregulated genes. Maas et al, J Immunol Patterns of Gene Expression: Autoimmune Diseases MAPK9: Relatively specific downregulation in RA patients who are not on MTX. MAP Kinase 9 Expression Decreased in Rheumatoid Arthritis SYMBOL PROTEIN HEALTHY RA P VALUE MAPK8 JNK NS MAPK9 JNK < MAPK10 P 38 alpha NS MAPK3 ERK NS MAPK1 ERK NS MAPK7 ERK NS Gene Expression values are relative to GAPDH. Healthy N=43 RA N=18 Downregulation of JNK Protein in RA Lymphocytes RA lymphocyte subsets (CD4, CD8, CD19) show low levels of JNK (top). The p38-associated protein is not decreased (bottom). RA; HC (N=7 to 18/group) Spurlock et al, submitted JNK Expression Inversely Correlated with C-reactive Protein Levels JNK detected by flow cytometry in CD4- gated PBMCs from RA patients who were not being treated with methotrexate. MAPK9 (above) and TP53 (right) measured in RA PBMCS by realtime PCR. MTX Treatment is Associated with Higher Levels of MAPK9, TP53 Spurlock et al, submitted 2

3 MTX treatment in RA patients: Higher levels of JNK protein in PBMCs Methotrexate Treatment: Increased JNK2 and Related Genes in vivo Flow Cytometric Detection of intracellular JNK in PBMCs from: Healthy controls (N=7) RA patients not on MTX (N=8) RA patients on MTX (N=4). MTX mg/week; followup 4-12 weeks MTX: Induces JNK Protein in vitro MTX Induces JNK-related Proteins Induced by MTX in Jurkat T cells: Jurkat T cells (A:Left) and human peripheral blood mononuclear cells (B:Right) MTX concentrations: 10-8, 10-7, 10-6 M JUN TP53 CDKN1A pjnk p21. JNK1/2 Requirement for MTX Action p53 p21 * * Jurkat cells: transfected with dominant negative JNK1/2 constructs cultured with MTX diminished upregulation p53 and p21. MAPK 9 (JNK2) mediates many cellular functions including apoptosis. Question: How is this pathway related to actions of MTX? 3

4 MTX Primes T cells for Increased Sensitivity to Apoptosis MTX primes Jurkat T cells for Increased Sensitivity to Apoptosis Jurkat T cells: pre-incubated with MTX 0.1 um for 48 hours, followed by addition of H or anti- Fas for 24 hours. Caspase 3 activation measured as a marker of apoptosis. Cells were pre-incubated with MTX 0.1 um for 48 hours, followed by addition of H or anti-fas x 24 hours. Caspase 3 activation measured as a marker of apoptosis. MTX Sensitization of Activated T Cells* for Apoptosis Uses Folate and ROS Pathways MTX primes cells for increased sensitivity to apoptosis. This effect is mediated by: Apoptosis bypassed by addition of BH 4 Generates ROS blocked by + BH 4 Production of reactive oxygen species. JNK upregulation and activation. JNK-dependent induction of other genes that promote apoptosis. *T cells activated with anti-cd3 + IL-2 Spurlock et al, submitted The T Cell Problem in RA T cells in RA: poor DNA damage repair inefficient mechanisms for removing damaged cells smoldering apoptosis accelerated T cell aging The MTX/JNK/RA hypothesis MTX: Inhibits DHFR which blocks reduction of dihydrobiopterin (BH 2 ) to tetrahydrobiopterin (BH 4 ) Decreased BH4 leads to uncoupling of NOS Increased ROS, JNK activation, induction of pro-apoptotic target genes Increased susceptibility to apoptotic signals Overall consequence: Correction of the senescent RA T cell repertoire?? 4

5 The Path Ahead in Rheumatoid Arthritis Methotrexate: Promotes apoptotic removal of autoreactive, activated T cells. ACKNOWLEDGEMENTS Can methotrexate also: Repair DNA damage response pathways and cell cycle checkpoint deficiencies? And shut down the danger signal? C. Spurlock, Vanderbilt University C. McAloose, Penn State University This work supported by: 5