New Directions in Therapy for Sjogren’s Syndrome

1. New Directions in Therapy for Sjogren’s Syndrome Robert I. Fox, MD., Ph.D. Scripps-Ximed La Jolla, CA robertfoxmd@mac.com (all slides on my website www.robertfoxmd.com)

2. Goals • Recognize that Sjogren’s has “benign” and “systemic” manifestations • Review the concept of “functional circuit” that links the inflammation of the mucosal circuit to the brain cortical regions that “sense pain” • Discuss the potential target of microglial cells and their cytokines/neurokines that may influence the perception of pain/dryness in SS

3. Background-1SS patients have Benign and Systemic Symptoms • Systemic symptoms—rash, arthritis, lung, kidney, lymphoma, hematologic--measured by ESSDAI which measures 12 organ domains. • Although ESSDAI usually less than 10, it has scale 0-100. • Improvement by at least 3.5 units is significant • Benign symptoms—dry and painful eyes/mouth, fatigue, cognitive, myalgia—measured by ESSPRI

4. Background-2 • Benign symptoms are leading cause of disability as identified by SS patients and poorly correlate with acute phase markers of inflammation • The failure to improve benign symptoms is the main reason why current therapies have failed in FDA trials

5. Background-1 Benign symptoms include: • Dry and Painful eyes • Dry and Painful Mouth • Fatigue, and Myalgia

6. Background-2 Benign Symptoms • These do not correlate well with acute phase reactants • They are more similar to “neuropathic” symptoms and involve “nociceptive” pain circuits • Nociceptive pain is caused when special nerve endings—called nociceptors –are activated and follow a particular pathway to cortex of brain

7. Use of Biologics in Systemic Manifestations of SS We have had modest success with biologics as measured by ESSDAI (clinical significance >3 units improvement) in SS patients with early disease • Rituximab • Belimumab • Abatacept • Tocilizumab

8. Background-2The functional Circuit • To understand “benign symptoms” and develop better therapies—we must review the concept of the functional circuit in SS • the interaction of immune activation on microglial cells and associated neurons • New targets include mTor and AKT pathways

9. Background-3The functional circuit in SS 1. Mucosal Surface (inflammatory cytokines and metalloproteinase) Brain Cortex Nociception (pain) glial cells and corticcal neurons 2. Midbrain Vth Nucleus (lymphocytes and glial cells) 3. Vascular (iNOS, CAMs, Chemokines) 4. Gland (lymphs, cytokines, metalloproteinase) We must understand these sites to treat “benign” symptoms These sites and their cytokines correlate with systemic manifestations

10. Does this apply to Sjogren’s syndrome? • Patients with early SS had corneal pain that decreased completely with topical anesthesia* • Patients with chronic SS showed only a partial (30% decrease) in eye pain after topical anesthetic* • Functional MRI (fMRI) showed nocioceptive pattern—called phantom pain amplification *Rosenthal et al

11. To study the mechanism of neurogenic or nociceptive pain we must use animal model-1 • The thrombospondin (-/-) mouse (TSP null) or the TGF-b receptor mutation both develop SS like disease • The mouse develops both oral and ocular lesions • The mouse develops ANA and SS-A antibodies • Thrombospondin is a matrix protein that plays a role in activation of latent TGF-b • Activated TGF-b promotes Treg and inhibits Th-17 (IFN-g) • Thus, TSP (null) has high levels of Th-17, IL-17 and IFN-g

12. Thrombospondin (-/-) mouse model of SS 4 wks 24 wks WT Tsp-/- Lacrimal gland biopsies The mouse has ANA+, SS-A+ TSP null can not activate TGF-b In absence TGF-b , continuous Th-17 TGF-b and cytokine activation stimulates mTor/AKT

13. The Pain Threshold is Lowered in the Tsp (-/-) mouse A pain stimuli that is innocuous in Wild Type does cause nociceptive pain in tsp (-/-) mouse model Thrombospondin (-/-) Mouse at 24 wks Where a trivial stimuli Causes pain response Wild type • Ocular chemical stress model of nociceptive pain • Le Bars D, Animal models of nociception. Pharmacological reviews 2001;53:597-652.

14. At the level of the Vth nerve(Tsp -/- mouse) • Microglial cells translate inflammatory signals that go to nociceptive cortex WT TSP (-/-) mTor and AKT activated in response to “lower stimuli” in the tsp (-/-) mouse

15. Of interest, the same regions are activated with physiologic or emotional stressors Emotional Physiological Similar pattern of Fos-ir in cortical neurons in response to distinct stressors

16. Summary-1 • Functional circuit needs to be considered when assessing “benign” symptoms of corneal or oral pain • Symptoms of oral/ocular pain do not correlate with markers of systemic inflammation (ESR/CRP) because the events are contained within the brainstem and cortex

17. Summary-2 • Afferents go to midbrain regions of Cranial Vth • Microglial cells are site of cytokine/neurokine interaction • Receptors and neurokines from microglial cells are therapeutic targets

18. Summary-3 • Novel targets include mTor and AKT pathways • These mTor/AKT pathways also implicated in chronic pain and depression—so we must collaborate with these neurochemists

19. Summary-4 • Cortical “memory” of nociceptive pain is well described in neurologic literature • fMRI indicates that nociceptive pain is the cause of benign symptoms in SS that do not correlate with acute phase reactants

20. Moulton et*. Al used fMRI in SS patients with chronic ocular painusing fMRI of nociceptive pain have been studied Cortical regions that activate with ocular pain signal at “benign stimuli levels” occur only in chronic SS patients with severe pain *Moulton EA, Becerra L, Rosenthal P, Borsook D. An Approach to Localizing Corneal Pain Representation in Human Primary Somatosensory Cortex. PloS one 2012;7:e44643.

21. Summary-5 • We have made advances in “systemic inflammation” and these are encouraging • For “drug licensing” we will also need to improve the patient’s “quality of life” symptoms of dryness, pain and fatigue • We need for “autoimmune” divisions to work with “neuro-chemistry” research divisions

22. どうもありがとうございました Takayuki Sumida,MD.-President Ichiro Saito, DDS (Tokyo) Kaz Tsubota, MD (Tokyo) Bruce Beutler, Ph.D. (Scripps TSRI) Ari Theofilopoulos (Scripps TSRI) V. Ramachandran, MD (Salk Neurology) P. Rosenthal (Harvard Corneal Pain Unit)

24. We are also looking atAdditional Targets of Interests Chemokines and their receptors (CCR) on vascular cells and lymphocytes TLR receptors: SLAC-15 that links Toll receptor and type 1 IFN Methylation modulators and siRNA Neural mediator circuits: • Receptors on cornea--substance P (TRPV1), VIP and CGRP pain receptors • TRPM8, TRPA1, and CGRP in trigeminal ganglion neurons • Trigeminal ganglion neurons- MCP-1, MIP-2, • CCR and CCL at the blood brain barrier

25. CCR and Blood Brain Barrier

26. Similar pattern of Fos-ir in PVH neurons in response to distinct stressors Emotional Physiological

27. We need to examine microglial pathways • Upon activation, microglia (M1 and M2) secrete inflammatory mediators that contribute to the resolution or to further enhancement of damage in the central nervous system (CNS). • Particularly, the role of the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) and glycogen synthase kinase-3

28. The tsp-null mouse allows us to look at the interaction of peripheral inflammation and microglial cells • Activation of microglial cells through mTor/AKT • In absence of thrombospondin, constitutive activation of Th17 and IFN-g activates microglial cells • Nociceptive (pain) pathway occurs through smad3 and non-smad pathways that involve mTor/AKT pathways in cranial nerve V