Research

Research Highlights: Rheumatology, Allergy, and Immunology

Examining the mechanism by which reactive oxygen species regulate chondrocyte signaling to contribute to osteoarthritis – Richard Loeser, MD

Measurement of intracellular H2O2 levels in chondrocytes using a redox biosensor
Measurement of intracellular H2O2 levels in chondrocytes using a redox biosensor. Fibronectin fragments found in arthritic cartilage generate low physiologic levels of H2O2 while the redox-cycling agent menadione generates high levels characteristic of oxidative stress.

Dr. Richard Loeser’s research focuses on basic mechanisms underlying cartilage breakdown in osteoarthritis (OA).  

In OA, the articular chondrocytes (cartilage cells) produce excessive amounts of matrix degrading enzymes including matrix metalloproteinases (MMPs). Cell signaling pathways that regulate MMP expression include the mitogen-activated protein (MAP) kinases. 

Reactive oxygen species (ROS), such as hydrogen peroxide (H2O2), have been found to be important second messengers in the regulation of cell signaling in numerous cell types including chondrocytes. This regulation occurs through reversible oxidation of reactive protein thiols present in a number of kinases and phosphatases. 

The Loeser lab recently reported in the Journal of Biological Chemistry that in human articular chondrocytes, the activity of the MAP kinase family member c-Jun N-terminal kinase 2 (JNK2) is regulated by the level of H2O2 Using dimedone-based chemical probes that react specifically with oxidized protein thiols (RSOH), they identified Cys-222 in JNK2, a residue not conserved in JNK1 or JNK3, as a redox-reactive site. Substitution of Cys-222 to alanine rendered JNK2 insensitive to H2O2.

Cumulatively, these findings indicate for the first time differential regulation of JNK2 signaling dependent on H2O2levels and point to a key cysteine residue regulating JNK2 activity. As levels of intracellular H2O2rise, a switch occurs from activation to inhibition of JNK2 activity, linking JNK2 regulation to the redox status of the cell. 

The research findings further showed that fragments of the matrix protein fibronectin that are found in arthritic cartilage generate low physiologic levels of H2O2(see figure) resulting in JNK2 activation which leads to increased MMP production while the compound menadione generates excessive levels of H2O2that inactivate JNK2 resulting in chondrocyte death.   
 

How 3D Chromatin Structure Shapes Human Development and Disease – Doug Phanstiel, PhD

DNA looping at the IL1B locus corresponds with binding of AP-1 and increased IL1B transcription
DNA looping at the IL1B locus corresponds with binding of AP-1 and increased IL1B transcription

Dr. Douglas Phanstiel studies the role of DNA looping in regulating gene transcription.  

Cell-type specific DNA loops connect genomic regulatory regions with gene promoters allowing for tightly regulated transcriptional programs during human development; however, the mechanisms of loop formation and subsequent transcriptional alteration remain poorly understood.

The Phanstiel lab uses DNA sequencing-based genomics and bioinformatic analysis to map DNA loops in human macrophages during development and activation.  

They found that the transcription factor complex Activator Protein 1 (AP-1) is highly enriched at the anchors of loops formed during macrophage development and are using CRISPR/Cas-9 to determine the role of AP-1 in loop-based gene regulation. 

The Phanstiel lab also develops new software for the analysis and visualization of proteomic and genomic data.  

They are applying these tools to understand how genetic variation outside of gene coding regions contribute to human diseases including Alzheimer’s Disease, Cancer, and Rheumatoid Arthritis.  

Relevant research:  

Alpha-gal mammalian meat food allergy – Scott Commins, MD, PhD 

Fluorescence-activated cell sorting of alpha-gal specific and IgE producing B cell plasmablast populations in subjects allergic to red meat and non-allergic control
Fluorescence-activated cell sorting of alpha-gal specific and IgE producing B cell plasmablast populations in subjects allergic to red meat (top 3 rows) and non-allergic control (bottom row)

Scott Commins, MD, PhD, is a physician scientist who is conducting research to better understand the regulation of IgE production in the recently described alpha-gal mammalian meat food allergy.  To do so he has focused on IgE-expressing (IgE+) B cells. These cells typically circulate in low abundance and are generally difficult to detect. However, recent improvements in technical methods have made their analysis more feasible. 

As shown in the figure, Dr. Commins has detected IgE+B cells that also stained positive for alpha-gal in several subjects allergic to mammalian meat. These alpha-gal-specific IgE+B cells were absent in healthy, non-allergic controls. 

Of total stained singlet cells, the population of alpha-gal-specific IgE+B cells was 0.092% (median) with a range of 0.013% to 0.15%. There was no association of alpha-gal-specific IgE+B cell frequency with reported severity of allergic reactions. Although B cell receptor signaling is thought to negatively regulate IgE responses, Dr. Commins’ research found that subjects reporting ongoing consumption of alpha-gal antigen in dairy form had generally higher proportion of antigen-specific IgE+B cells. 

Future studies will track these double-positive B cells longitudinally to assess the impact of additional tick bites. 

One of Dr. Commins’ recent grants, an R01 AI135049, is entitled, “Understanding alpha-gal red meat allergy,” and is funded by NIAID for 5 years. The proposed work aims to define both the cause and the mechanism of α-gal IgE response, as well as identifying the antigen responsible for the delayed food reactions. Ultimately, these studies will provide insight into the factors that govern allergic responses and control anaphylaxis. 

Broad Based Osteoarthritis Research, Including Longitudinal Population Studies, and Innovative Uses of Imaging Technologies Such as Musculoskeletal Ultrasound – Amanda Nelson, MD, MSCR, RhMSUS

Radiographically defined hip morphologies
Radiographically defined hip morphologies

Amanda E. Nelson, MD, MSCR, RhMSUS, is a rheumatologist and epidemiologist with the UNC Thurston Arthritis Research Center, and co-PI of the large, ongoing, Johnston County Osteoarthritis Project (JoCo OA). Her research primarily centers around various aspects of osteoarthritis epidemiology, with a focus on ultrasound, joint shape and multiple joint involvement. 

Dr. Nelson is a nationally recognized expert concerning the innovative use of musculoskeletal ultrasound in the study of osteoarthritis (OA). A portion of her work is funded by the Rheumatology Research Foundation. One aspect of her research includes musculoskeletal ultrasound’s benefits compared to X-rays or MRIs for studying OA, including the fact that it is cost-effective, widely available, reliable, and can often identify OA changes at an earlier stage, when early interventions for the patient are more feasible.  

Dr. Nelson’s publications during 2018 include a paper in Seminars in Arthritis and Rheumatism describing a systematic review of definitions of multiple joint OA, as well as the frequency of these definitions in JoCo OA and their association with pain and function (1). Dr. Nelson has also published research findings focused on features of hip shape and how these relate to OA risk (2), and provided an overview of the Clinical OA literature at the 2017 Osteoarthritis Research Society International (OARSI) meeting, which was published in Osteoarthritis and Cartilage in 2018.

Relevant Research:

  1. Gullo TR, Golightly YM, Cleveland RJ, Renner JB, Callahan LF, Jordan JM, Kraus VB, Nelson AE. Defining multiple joint osteoarthritis, its frequency and impact in a community-based cohort. Semin Arthritis Rheum. 2018 Oct 9. pii: S0049-0172(18)30508-0. doi: 10.1016/j.semarthrit.2018.10.001. [Epub ahead of print] PubMed PMID: 30390991.
  2. Raveendran R, Stiller JL, Alvarez C, Renner JB, Schwartz TA, Arden NK, Jordan JM, Nelson AE. Population-based prevalence of multiple radiographically-defined hip morphologies: the Johnston County Osteoarthritis Project. Osteoarthritis Cartilage. 2018 Jan;26(1):54-61. doi: 10.1016/j.joca.2017.10.002. Epub 2017 Oct 9. PubMed PMID: 29024801; PubMed Central PMCID: PMC5732866.

Dr. Nelson has also been a co-author on numerous scientific papers with her UNC Thurston colleagues on related topics.  
 

Biomechanical Risk Factors for Osteoarthritis: The Johnston County Osteoarthritis Project – Yvonne Golightly, PT, PhD

Beighton Criteria for Joint HypermobilityDr. Yvonne Golightly is a musculoskeletal epidemiologist and a physical therapist whose research interests include osteoarthritis (OA), musculoskeletal injury, lower body biomechanics, physical activity, rehabilitation, and OA-related biomarkers. She is also the co-Principal Investigator for the Johnston County Osteoarthritis Project (JoCo OA).

Dr. Golightly and her colleagues focus on studying biomechanical risk factors for OA, particularly limb length inequality and joint hypermobility. She led the first large population-based study demonstrating that limb length inequality is associated with knee and hip OA and symptoms based on data from JoCo OA, which showed that among obese individuals, limb length inequality was associated with progressive radiographic knee OA. Limb length inequality appears to be a modifiable risk factor for incident and progressive disability outcomes when accounting for OA.

Dr. Golightly currently leads an R01 titled “The Role of Joint Hypermobility in Lower Body Osteoarthritis.” This ongoing project includes JoCoOA data. In cross-sectional analyses, joint hypermobility was associated with ankle & foot radiographic OA & pain. Joint hypermobility was not associated with low back pain and lumbar spine OA, although it was found to be inversely associated with the trunk flexion maneuver.

Joint hypermobility was more common in Whites than African-Americans in this cohort. Hypermobility was associated with lower back symptoms in Whites, but not in African-Americans. Associations between joint hypermobility and other knee, hip, or lumbar spine/facet OA variables were not statistically significant and did not differ by race.

Relevant research:
 

 

Improving Outcomes for Patients with Osteoarthritis – Kelli Allen, PhD

Change in self-reported pain, stiffness and function based on number of PT sessions
Change in self-reported pain, stiffness and function based on number of PT sessions

Kelli Allen, PhD, is a health services researcher and exercise scientist whose research focuses on strategies to improve care and outcomes for patients with chronic musculoskeletal conditions, especially osteoarthritis. Dr. Allen’s team focuses on pragmatic trials, examining interventions that can be disseminated and implemented in real-world clinical and community settings.  

Dr. Allen and colleagues, in partnership with UNC University Physical Therapy clinics, recently completed a clinical trial that compared physical therapy and internet-based exercise training for knee osteoarthritis. The main results of this trial showed that although these two interventions resulted in similar changes in pain and function, neither differed substantially from a control group.   

However, an important secondary finding of this study was that among patients in the physical therapy study arm, those who received more visits – particularly 6-8 visits – had greater, clinically relevant improvements in pain and function. These findings support the principle of encouraging patients to participate in 6-8 outpatient physical therapy visits for knee osteoarthritis.  

Relevant research includes:   

Dr. Allen’s research team is also collaborating with primary care clinics in the UNC Physicians Network on a new study that aims to improve physical activity levels among patients with osteoarthritis, through screening, phone-based coaching and connection with community programs. 
 

Clinical trials and development of diagnostic & prognostic tools that directly impact the care of Lupus patients – Saira Z. Sheikh, MD

Saira Z. Sheikh, MD is an Allergist/Immunologist and Rheumatologist, whose work focuses on answering scientific questions that directly impact the care of patients with Lupus and Sjogren’s. Given that only one drug has been approved by the FDA for Lupus in the past 50 years, there is an unmet need for new therapeutics and other interventions to improve the lives of Lupus patients. Dr. Sheikh is Principal Investigator on several clinical trials studying novel therapies for these diseases.

Dr. Sheikh is keenly aware of the health disparities that exist in Lupus clinical trials, and is leading two national initiatives around this important issue to develop real-world, practical models to improve education of patients and change providers practice to promote inclusion of minority patients in lupus clinical trials. Dr. Sheikh is also interested in using technology based applications to improve education and understanding about lupus clinical trials, and at UNC is leading project PURPLE (Programs to address Unmet needs and promote Representation of all Participants in Lupus clinical trials using mobile technology for Engagement).

Dr. Sheikh is working collaboratively with basic scientists and a local biotech company on translational projects that are looking to develop an epigenetic histone peptide microarray platform (EpiSeraTM) as a diagnostic and prognostic tool for autoimmune diseases. Another project is focused on understanding mechanisms for development of premature coronary artery disease in this patient population.

Cartoon depiction of the stepwise procedure for autoantibody screening on a histone peptide microarray

Walk SLE - Results from a pilot study exploring Walk with Ease, a self-directed walking program, in Lupus patients

Dr. Sheikh and her team recently completed a pilot study, “Walk SLE” that was the first study examining an evidence-based, self-directed exercise program (Walk with Ease) in Lupus patients. They found that this is a feasible, low-cost program that may decrease lupus related fatigue and stiffness, improve activity and promote long-term lifestyle changes.

Relevant research: