Thermal signature analysis as a novel method for evaluating inflammatory arthritis activity

Thermal imaging in rheumatoid arthritis knee joints and its correlation with power Doppler ultrasound

Background

Power Doppler ultrasound (PDUS) is an established non-invasive modalities for quantification of inflammation, which has a bearing on the assessment of disease activity in rheumatoid arthritis (RA). However, PDUS has several disadvantages including cost of equipment, steep learning curve and inter-observer variability. Thermal imaging has emerged as a simple, powerful tool for mapping the heat distribution pattern and has the potential to document and quantify disease activity in RA. The objective was to study the thermal imaging pattern of inflamed knee joints in cases of RA and its correlation with PDUS.

Methods

This pilot case-control study was carried out at the rheumatology centre in India including 100 subjects (50 controls and 50 RA patients). All participants underwent thermal imaging and PDUS for the knee joints. The mean temperatures in area of interest in knee, thigh and knee-thigh differential were analysed in comparison with PDUS findings.

Results

RA subjects had significantly higher mean knee temperature and mean knee-thigh temperature differential compared with controls (p value < 0.00001). PDUS documented inflammation strongly correlated with knee-thigh temperature differential.

Conclusion

There was a statistically significant difference in mean knee temperature as well as mean knee-thigh temperature differential of inflamed versus control knees. Thermal imaging has the potential to become simple, objective, cost-effective and reliable tool for diagnosis and assessment of disease activity in inflammatory arthritis.

Ratiometric Fluorescence and Afterglow Lifetime Dual-Channel Nanoprobe for Simultaneous Imaging of HOCl and Temperature in Arthritis

Arthritis is a joint disorder that potentially causes permanent joint damage and eventual disability without effective treatment. Clinical detection methods, including in vitro blood tests and anatomical imaging, still have limitations in achieving real-time in situ early detection of arthritis. In this work, a dual-channel luminescence nanoprobe (AGNPs-Cy7) is reported, which combines a cyanine dye and a photochemical reaction-based afterglow system for real-time in vivo imaging of arthritis. AGNPs-Cy7 simultaneously detect hypochlorous acid (HOCl) and temperature, two important indicators associated with the early development of arthritis, by monitoring the respective changes in independent ratiometric fluorescence and afterglow lifetime signals. The anti-interference properties of both the ratiometric fluorescence signal and afterglow lifetime signal enhance sensing accuracy compared to the single luminescence intensity. The developed probe successfully reveals the simultaneous increase in HOCl concentration and temperature in an arthritis mouse model.

Validating within-limb calibrated algorithm using a smartphone attached infrared thermal camera for detection of arthritis in children

OBJECTIVES

To determine the impact of physical activity on temperature after within-limb calibration (TAWiC) measures and their reproducibility. To determine if thermal imaging from a smartphone attached thermal camera is comparable to thermal imaging using a handheld thermal camera for detection of arthritis in children.

METHODS

Children without symptoms were enrolled to the "asymptomatic exercise cohort", and received infrared imaging, using a standard handheld camera, after initial resting period, after activity, and after second resting period. Children seen in the rheumatology clinic with knee pain were enrolled into the "symptomatic knee pain cohort" and received imaging with both the smartphone-attached and handheld cameras before a routine clinical exam. TAWiC was defined as the temperature differences between joint and ipsilateral mid-tibia as the main readout for arthritis detection.

RESULTS

The asymptomatic exercise cohort demonstrated notable changes in absolute and TAWiC temperatures collected by thermal imaging after physical activity, and temperatures did not consistently return to pre-activity levels after a second period of rest. The 95th TAWiC from anterior view were, resting one -0.1 C (0.5), activity -0.7 C (0.5), resting two -0.2 C (0.6) (resting 1 vs resting 2, p-value = 0.13). In the symptomatic knee pain cohort, the smartphone attached and handheld thermal cameras performed similarly in regards to detection of joint inflammation and evaluation of joint temperature using the TAWiC algorithm, with high sensitivity of 80% (55.2-100.0%) and specificity of 84.2% (76.0-92.4%) in the anterior knee view when compared with the gold standard joint exam performed by a pediatric rheumatologist. The mean 95th TAWiC temperature difference between the two cameras was -0.1 C (-0.1 to 0.0) (p = 0.0004).

CONCLUSIONS

This study showed continued validity of the TAWiC algorithm across two distinct thermal camera platforms and demonstrates promise for improved accessibility and utility of this technology for arthritis detection.

A Thermographic Disease Activity Index for remote assessment of rheumatoid arthritis

OBJECTIVES

Remote assessment of patients with rheumatoid arthritis (RA) has increased during recent years. However, telematic consultations preclude the possibility of carrying out a physical examination and obtaining objective inflammation. In this study, we developed and validated two novel composite disease activity indexes (Thermographic Disease Activity Index (ThermoDAI) and ThermoDAI-CRP) based on thermography of hands and machine learning, in order to assess disease activity easily, rapidly and without formal joint counts.

METHODS

ThermoDAI was developed as the sum of Thermographic Joint Inflammation Score (ThermoJIS), a novel joint inflammation score based on the analysis of thermal images of the hands by machine learning, the Patient Global Assessment (PGA) and, for ThermoDAI-CRP, the C reactive protein (CRP). Construct validity was tested in 146 patients with RA by using Spearman's correlation with ultrasound-determined grey-scale synovial hypertrophy (GS) and power Doppler (PD) scores, CDAI, SDAI and DAS28-CRP.

RESULTS

Correlations of ultrasound scores with ThermoDAI (GS=0.52; PD=0.56) and ThermoDAI-CRP (GS=0.58; PD=0.61) were moderate to strong, while the correlations of ultrasound scores with PGA (GS=0.35; PD=0.39) and PGA+CRP (GS=0.44; PD=0.46) were weak to moderate. ThermoDAI and ThermoDAI-CRP also showed strong correlations with Clinical Disease Activity Index (ρ>0.83), Simplified Disease Activity Index (ρ>0.85) and Disease Activity Score with 28-Joint Counts-CRP (ρ>0.81) and high sensitivity for detecting active synovitis using remission criteria.

CONCLUSIONS

ThermoDAI and ThermoDAI-CRP showed stronger correlations with ultrasound-determined synovitis than PGA and PGA + CRP, thus presenting an opportunity to improve remote consultations with patients with RA.

Iron-Based Magnetic Nanosystems for Diagnostic Imaging and Drug Delivery: Towards Transformative Biomedical Applications

The advancement of biomedicine in a socioeconomically sustainable manner while achieving efficient patient-care is imperative to the health and well-being of society. Magnetic systems consisting of iron based nanosized components have gained prominence among researchers in a multitude of biomedical applications. This review focuses on recent trends in the areas of diagnostic imaging and drug delivery that have benefited from iron-incorporated nanosystems, especially in cancer treatment, diagnosis and wound care applications. Discussion on imaging will emphasise on developments in MRI technology and hyperthermia based diagnosis, while advanced material synthesis and targeted, triggered transport will be the focus for drug delivery. Insights onto the challenges in transforming these technologies into day-to-day applications will also be explored with perceptions onto potential for patient-centred healthcare.

Assessment of inflammation in patients with rheumatoid arthritis using thermography and machine learning: a fast and automated technique

Objectives

Sensitive detection of joint inflammation in rheumatoid arthritis (RA) is crucial to the success of the treat-to-target strategy. In this study, we characterise a novel machine learning-based computational method to automatically assess joint inflammation in RA using thermography of the hands, a fast and non-invasive imaging technique.

Methods

We recruited 595 patients with arthritis and osteoarthritis, as well as healthy subjects at two hospitals over 4 years. Machine learning was used to assess joint inflammation from the thermal images of the hands using ultrasound as the reference standard, obtaining a Thermographic Joint Inflammation Score (ThermoJIS). The machine learning model was trained and tuned using data from 449 participants with different types of arthritis, osteoarthritis or without rheumatic disease (development set). The performance of the method was evaluated based on 146 patients with RA (validation set) using Spearman’s rank correlation coefficient, area under the receiver-operating curve (AUROC), average precision, sensitivity, specificity, positive and negative predictive value and F1-score.

Results

ThermoJIS correlated moderately with ultrasound scores (grey-scale synovial hypertrophy=0.49, p<0.001; and power Doppler=0.51, p<0.001). The AUROC for ThermoJIS for detecting active synovitis was 0.78 (95% CI, 0.71 to 0.86; p<0.001). In patients with RA in clinical remission, ThermoJIS values were significantly higher when active synovitis was detected by ultrasound.

Conclusions

ThermoJIS was able to detect joint inflammation in patients with RA, even in those in clinical remission. These results open an opportunity to develop new tools for routine detection of joint inflammation.

Magnetic cryogels as a shape-selective and customizable platform for hyperthermia-mediated drug delivery

Cryogels consisting of polyvinyl alcohol and iron (II, III) oxide magnetic nanoparticles coated with a model drug—acetaminophen, were developed as a tunable platform for thermally triggered drug release, based on shape-selective heat transfer. Two different shapes of cryogels; discs and spherical caps, were formed via adding polymer-nanoparticle-drug mixtures into 3D printed molds, followed by freeze-thawing five times. No additional chemical crosslinking agents were used for gel formation and the iron oxide nanoparticles were coated with acetaminophen using only citric acid as a hydrogen-bonding linker. The two gel shapes displayed varying levels of acetaminophen release within 42–50 °C, which are ideal temperatures for hyperthermia induced drug delivery. The amount and time of drug-release were shown to be tunable by changing the temperature of the medium and the shape of the gels, while keeping all other factors (ex. gel volume, surface area, polymer/nanoparticle concentrations and drug-loading) constant. The discs displayed higher drug release at all temperatures while being particularly effective at lower temperatures (42–46 °C), in contrast to the spherical caps, which were more effective at higher temperatures (48–50 °C). Magnetic hyperthermia-mediated thermal imaging and temperature profiling studies revealed starkly different heat transfer behavior from the two shapes of gels. The disc gels retained their structural integrity up to 51 °C, while the spherical caps were stable up to 59 °C, demonstrating shape-dependent robustness. The highly customizable physicochemical features, facile synthesis, biocompatibility and tunable drug release ability of these cryogels offer potential for their application as a low cost, safe and effective platform for hyperthermia-mediated drug delivery, for external applications such as wound care/muscle repair or internal applications such as melanoma treatment.

Infrared Thermography as a Non-Invasive Tool in Musculoskeletal Disease Rehabilitation—The Control Variables in Applicability—A Systematic Review

In recent years, the usefulness of infrared thermography (IRT) as a valuable supplementary imaging method in medical diagnostics, as well as for assessing the effects of the treatment of musculoskeletal injuries, has been increasingly confirmed. At the same time, great importance is attached to the standards of thermographic research, the fulfillment of which determines the correct methodology and interpretation of the results. This article discusses the medical applications of infrared thermography in musculoskeletal system diseases, with particular emphasis on its usefulness in assessing the therapeutic effects of physical treatments used in rehabilitation. The literature from the last decade that is available in the Medline and Web of Science databases has been reviewed. Among the physiotherapeutic methods used, the following were selected that directly affect the musculoskeletal system: cryotherapy, laser therapy, electrotherapy, diathermy, and massage. The article summarizes all the guidelines and recommendations for IR imaging in medicine and rehabilitation.

Infrared Thermography for the Evaluation of Inflammatory and Degenerative Joint Diseases: A Systematic Review

OBJECTIVE

Inflammation plays a central role in the pathophysiology of rheumatic diseases as well as in osteoarthritis. Temperature, which can be quantified using infrared thermography, provides information about the inflammatory component of joint diseases. This systematic review aims at assessing infrared thermography potential and limitations in these pathologies.

DESIGN

A systematic review was performed on 3 major databases: PubMed, Cochrane library, and Web of Science, on clinical reports of any level of evidence in English language, published from 1990 to May 2021, with infrared thermography used for diagnosis of osteoarthritis and rheumatic diseases, monitoring disease progression, or response to treatment. Relevant data were extracted, collected in a database, and analyzed for the purpose of this systematic review.

RESULTS

Of 718 screened articles 32 were found to be eligible for inclusion, for a total of 2094 patients. Nine studies reported the application to osteoarthritis, 21 to rheumatic diseases, 2 on both. The publication trend showed an increasing interest in the last decade. Seven studies investigated the correlation of temperature changes with osteoarthritis, 16 with rheumatic diseases, and 2 with both, whereas 2 focused on the pre-post evaluation to investigate treatment results in patients with osteoarthritis and 5 in patients with rheumatic diseases. A correlation was shown between thermal findings and disease presence and stage, as well as the clinical assessment of disease activity and response to treatment, supporting infrared thermography role in the study and management of rheumatic diseases and osteoarthritis.

CONCLUSIONS

The systematic literature review showed an increasing interest in this technology, with several applications in different joints affected by inflammatory and degenerative pathologies. Infrared thermography proved to be a simple, accurate, noninvasive, and radiation-free method, which could be used in addition to the currently available tools for screening, diagnosis, monitoring of disease progression, and response to medical treatment.

A Novel Algorithm using Within-leg Calibration for Enhanced Accuracy of Detection of Arthritis by Infrared Thermal Imaging in Children

OBJECTIVE

To standardize and improve the accuracy of detection of arthritis by thermal imaging.

METHODS

Children with clinically active arthritis in the knee or ankle, as well as healthy controls, were enrolled to the development cohort and another group of children with knee symptoms were enrolled to the validation cohort. Ultrasound was performed for the arthritis subgroup for the development cohort. Joint exam by certified rheumatologists was used as a reference for the validation cohort. Infrared thermal data were analyzed using a custom software. Temperature after within-limb calibration (TAWiC) was defined as the temperature differences between joint and ipsilateral midtibia. TAWiC of knees and ankles was evaluated using ANOVA across subgroups. Optimal thresholds were determined by receiver operating characteristic (ROC) analysis using Youden index.

RESULTS

There were significant differences in mean and 95^th TAWiC of knee in anterior, medial, lateral views, and of ankles in anterior view, between inflamed and uninflamed counterparts (p<0.05). The area under the curve (AUC) was higher by 36% when using TAWiC_Knee than those when using absolute temperature. Within validation cohort, the sensitivity of accurate detection of arthritis in knee using both mean and 95^th TAWiC from individual views or combined all 3 views ranged from 0.60 to 0.70 and the specificity was greater than 0.90 in all views.

CONCLUSION

Children with active arthritis or tenosynovitis in knees or ankles exhibited higher TAWiC than healthy joints. Our validation cohort study showed promise of the clinical utility of infrared thermal imaging for arthritis detection.

Thermal imaging ruled out as a supplementary assessment in patients with fibromyalgia: A cross-sectional study

BACKGROUND

The diagnosis of fibromyalgia syndrome (FMS) syndrome is often complicated and relies on diagnostic criteria based mostly on the symptoms reported by patients. Implementing objective complementary tests would be desirable to better characterize this population.

OBJECTIVE

The purpose of this cross-sectional study was to compare the skin temperature at rest using thermography in women with FMS and healthy women.

METHODS

Eighty-six women with FMS and 92 healthy controls volunteered to participate. The temperature of all participants was measured by infra-red thermography, registering the skin surface temperature (minimum, maximum and average) at rest in different areas: neck, upper and lower back, chest, knees and elbows. In order to analyze the differences in the skin temperature between groups, inferential analyses of the data were performed using Mann-Whitney U test.

RESULTS

The results showed no significant difference in skin temperature between groups in the neck, upper back, chest and elbows (p>0.05). The lower back and knees areas showed significant differences between groups (p<0.05), although these differences did not reach a minimum of clinically detectable change.

CONCLUSIONS

Women with fibromyalgia presented no clinically meaningful reduction or difference in skin temperature at rest when compared with a group of healthy women. The infra-red thermography is not an effective supplementary assessment tool in women with fibromyalgia.

Accurate In Vivo Nanothermometry through NIR-II Lanthanide Luminescence Lifetime

Luminescence nanothermometry is promising for noninvasive probing of temperature in biological microenvironment at nanometric spatial resolution. Yet, wavelength- and temperature-dependent absorption and scattering of tissues distort measured spectral profile, rendering conventional luminescence nanothermometers (ratiometric, intensity, band shape, or spectral shift) problematic for in vivo temperature determination. Here, a class of lanthanide-based nanothermometers, which are able to provide precise and reliable temperature readouts at varied tissue depths through NIR-II luminescence lifetime, are described. To achieve this, an inert core/active shell/inert shell structure of tiny nanoparticles (size, 13.5 nm) is devised, in which thermosensitive lanthanide pairs (ytterbium and neodymium) are spatially confined in the thin middle shell (sodium yttrium fluoride, 1 nm), ensuring being homogenously close to the surrounding environment while protected by the outmost calcium fluoride shell (CaF₂ , ≈2.5 nm) that shields out bioactive milieu interferences. This ternary structure enables the nanothermometers to consistently resolve temperature changes at depths of up to 4 mm in biological tissues, having a high relative temperature sensitivity of 1.4-1.1% °C^-1 in the physiological temperature range of 10-64 °C. These lifetime-based thermosensitive nanoprobes allow for in vivo diagnosis of murine inflammation, mapping out the precise temperature distribution profile of nanoprobes-interrogated area.

Refinement and validation of infrared thermal imaging (IRT): a non-invasive technique to measure disease activity in a mouse model of rheumatoid arthritis

Background

The discovery and development of new medicines requires high-throughput screening of possible therapeutics in a specific model of the disease. Infrared thermal imaging (IRT) is a modern assessment method with extensive clinical and preclinical applications. Employing IRT in longitudinal preclinical setting to monitor arthritis onset, disease activity and therapeutic efficacies requires a standardized framework to provide reproducible quantitative data as a precondition for clinical studies.

Methods

Here, we established the accuracy and reliability of an inexpensive smartphone connected infrared (IR) camera against known temperature objects as well as certified blackbody calibration equipment. An easy to use protocol incorporating contactless image acquisition and computer-assisted data analysis was developed to detect disease-related temperature changes in a collagen-induced arthritis (CIA) mouse model and validated by comparison with two conventional methods, clinical arthritis scoring and paw thickness measurement. We implemented IRT to demonstrate the beneficial therapeutic effect of nanoparticle drug delivery versus free methotrexate (MTX) in vivo.

Results

The calibrations revealed high accuracy and reliability of the IR camera for detecting temperature changes in the rheumatoid arthritis animal model. Significant positive correlation was found between temperature changes and paw thickness measurements as the disease progressed. IRT was found to be superior over the conventional techniques specially at early arthritis onset, when it is difficult to observe subclinical signs and measure structural changes.

Conclusion

IRT proved to be a valid and unbiased method to detect temperature changes and quantify the degree of inflammation in a rapid and reproducible manner in longitudinal preclinical drug efficacy studies.

Musculoskeletal applications of infrared thermography on back and neck syndromes: a systematic review

INTRODUCTION

Thermography is a noninvasive method to detect temperature changes on or near the surface of the body. Despite its utility has not yet been fully verified, it may be used as a complementary method to screening and/or monitoring treatment effectiveness. This systematic review evaluates the role of infrared thermography as a helpful outcome measure tool in subjects with back and neck syndromes.

EVIDENCE ACQUISITION

A literature search was conducted across the National Library of Medicine (MEDLINE), Web of Science and Scopus databases for studies that evaluated the role of infrared thermography as a helpful outcome measure tool in subjects with back and neck syndromes. The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA).

EVIDENCE SYNTHESIS

The search strategy and selection criteria yielded 812 articles. From these, 268 duplicates were removed, and only 16 were in line with the aim of this review. Ultimately, only seven precisely fulfilled the inclusion and exclusion criteria and were included in the review. According to the articles reviewed, thermography seems to give an objective notion of change in inflammatory activity, which can corroborate the usefulness of treatment or the improvement/worsening of the patient's symptoms. The overall quality of research was uneven in the study design, endpoint measures, and sample characteristics.

CONCLUSIONS

The number of high-quality studies of the role of infrared thermography in patients with back and neck syndromes remains limited. More than a diagnostic tool, thermography can be an objective tool for monitoring the effectiveness of treatment by identifying deviations from a healthy state.

Thermal and Visual Imaging to Assist with Juvenile Idiopathic Arthritis Examination of the Knees

Juvenile idiopathic arthritis (JIA) causes inflammation of the joints, and it is frequently associated with their pain and stiffness. Its timely diagnosis is important to avoid its progressive damage to the bones and cartilage. Increases in the joint’s temperature and redness could be indicators of active JIA, hence their accurate quantification could assist with diagnosis. Thermal and visual images of the knees in 20 JIA participants (age: mean = 11.2 years, standard deviation = 2.3 years) were studied. The median temperature of knees with active inflammation was 3.198% higher than that of inactive knees. This difference, examined by a Wilcoxon signed-rank test, was statistically significant (p = 0.0078). In six out of the eight participants who had one active inflamed knee, thermal imaging identified the corresponding knee as warmer. In 16 out of 20 participants, the knee identified as warmer by thermal imaging was also identified as having a greater colour change by visual imaging as compared to their respective reference regions. The devised methods could accurately quantify the colour and temperature of the knees. It was concluded that thermal and visual imaging methods can be valuable in examining JIA. Further studies involving a larger number of participants and more detailed explorations would be needed prior to clinical application.

Potential clinical utility of a novel optical tomographic imaging for the quantitative assessment of hand rheumatoid arthritis

Optical tomographic imaging (OTI) was reported to be a novel technique for the early diagnosis and disease activity assessment of rheumatoid arthritis (RA). This study aimed to evaluate the clinical utility of OTI for the detection of hand synovitis of RA patients. Manu-scan was used to perform imaging targeting the proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints in 12 RA patients and three controls. The enrolled RA patients also underwent magnetic resonance imaging (MRI) and bone scintigraphy (BS) to provide reference images. Of the 181 joints feasible for OTI analysis, 140 joints (111 in RA patients and 29 in controls, 77.3%) in which the difference of the OTI indices in the two measurements was within 20% were evaluated. The OTI indices in RA joints were significantly lower than those in control joints (p < 0.001). Overall, the OTI indices in RA joints decreased as the synovitis grades on MRI or BS increased. Moreover, OTI was able to discriminate between RA and control joints (AUC = 0.815, 95% CI 0.739-0.891), even if RA joints were normal on physical examination (AUC = 0.714, 95% CI 0.594-0.834). OTI was in good agreement (kappa = 0.60) with MRI for evaluating synovitis in RA patients and showed positive results in 11.4% of clinically asymptomatic joints. OTI in this study showed the potential to be a supplementary imaging modality for the quantification of synovial inflammation in PIP and MCP joints of RA patients. Further large-scale trials are needed to confirm these findings.

Pre-Clinical Testing of Microwave Radiometer and a Pilot Study on the Screening Inflammation of Knee Joints

This article presents the pre-clinical evaluation of our custom-built, single-band microwave radiometer centered at 1.3 GHz for deep tissue thermometry, and a pilot study on volunteers for passive detection of inflammation in knee joints. The electromagnetic (EM) compatibility of the battery-operated radiometer for clinical use was assessed as per International Special Committee on Radio Interference (CISPR) 22 standard. The ability to detect inflammation in knee joints was assessed using a substrate integrated waveguide antenna connected to the radiometer. EM compatibility tests carried out in the laboratory indicated device immunity to intentional radiated interference up to -20 dBm injected power in the global system for mobile communication frequency band, and pre-compliance to CISPR 22 standard. Radiometer temperature measurements recorded at the lateral and medial aspects of both knees of 41 volunteers indicated mean temperature greater than 33°C for the diseased sites compared with the mean temperature of 28°C measured for the healthy sites. One-way analysis of variance statistics indicated significantly (P < 0.005) higher radiometer temperature at the diseased sites unlike the healthy sites. Thus, the EM pre-compliance of the device and the potential to measure deep tissue inflammation were demonstrated. Bioelectromagnetics. 2019;40:402-411. © 2019 Bioelectromagnetics Society.

Hyperthermia in rheumatic diseases. A promising approach?

Hyperthermia is a method applied in the treatment of many diseases, including rheumatic diseases. There are relatively few reports concerning the role of that method in the treatment of these diseases, and most studies have not been randomised. Hyperthermia includes directed application of thermal energy. The aim of that therapy is to overcome the body’s natural thermoregulation mechanism through application of external heat sources such as electromagnetic radiation of various frequencies, or ultrasound. Usually, temperatures are used within the 38.5–43° range. Hyperthermia can be applied as topical, regional, or systemic treatment (the latter is called hyperthermia of the whole body). In rheumatology, mainly the effect of hyperthermia on the immune system of the body is used. That effect depends on the type of hyperthermia and temperatures applied. Best documented are the effects of hyperthermia in fibromyalgia and ankylosing spondylitis.

Ratiometric nanothermometer in vivo based on triplet sensitized upconversion

Temperature is an essential factor that counts for living systems where complicated vital activities are usually temperature dependent. In vivo temperature mapping based on non-contact optical approach will be beneficial for revealing the physiological phenomena behind with minimized influence to the organism. Herein, a highly thermal-sensitive upconversion system based on triplet–triplet annihilation (TTA) mechanism is pioneered to indicate body temperature variation sensitively over the physiological temperature range. The temperature-insensitive NaYF₄: Nd nanophosphors with NIR emission was incorporated into the temperature-responsive TTA-upconversion system to serve as an internal calibration unit. Consequently, a ratiometric thermometer capable of accurately monitoring the temperature changes in vivo was developed with high thermal sensitivity (~7.1% K⁻¹) and resolution (~0.1 K).

Though luminescence imaging is a promising approach for contactless thermometry in vivo, the low thermal sensitivity of existing thermometers limits its potential. Here, the authors develop a high-sensitivity ratiometric nanothermometer based on triplet-sensitized upconversion.

Thermal tomography for monitoring tumor response to neoadjuvant chemotherapy in women with locally advanced breast cancer

BACKGROUND & AIMS

This study aims to analyze the feasibility and predictive value of thermal tomography (TT) for monitoring early treatment response in patients with locally advanced breast cancer (LABC) receiving neoadjuvant chemotherapy (NAC).

METHODS

Patients with LABC who were due to receive six cycles of NAC were examined by TT prior to NAC, the second cycle of NAC, the fourth cycle of NAC and surgery. Changes in TT parameters and ultrasonography were correlated with pathologic response to NAC, and the predictive value was assessed.

RESULTS

Forty-four patients were evaluable for response (25 pathologic responders and 19 nonresponders). As early as after the first cycle of NAC, changes in the TT parameters ΔTs, ΔTn, and ΔTa correlated significantly with pathologic response (P < 0.05). The best predictor of pathologic response after the 6th cycle of NAC was TT (area under the receiver operating characteristic curve, 0.794), as opposed to cross-sectional areas and the longest diameter by ultrasonography.

CONCLUSIONS

TT allows for monitoring early tumor response to NAC and can predict pathologic response in the early stages of therapy. Therefore, TT could be used as a novel imaging modality to monitor NAC treatment.

Methods for Testing Immunological Factors

Hypersensitivity reactions can be elicited by various factors: either immunologically induced, i.e., allergic reactions to natural or synthetic compounds mediated by IgE, or non-immunologically induced, i.e., activation of mediator release from cells through direct contact, without the induction of, or the mediation through immune responses. Mediators responsible for hypersensitivity reactions are released from mast cells. An important preformed mediator of allergic reactions found in these cells is histamine. Specific allergens or the calcium ionophore 48/80 induce release of histamine from mast cells. The histamine concentration can be determined with the o-phthalaldehyde reaction.

Lower temperature at the wound edge detected by thermography predicts undermining development in pressure ulcers: a pilot study

Undermined pressure ulcers (PUs) are troublesome complications that are likely to delay wound healing. Early skin incision and debridement can prevent the deterioration of undermined PUs, thus it is necessary to identify devitalised tissue areas to determine the appropriate timing for such interventions. This retrospective cohort study evaluated whether a lower temperature at the wound edge than the wound bed and periwound skin, detected by thermography, can predict undermining development in PUs 1 week after the assessment. Twenty-two participants with category III, IV, or unstageable PUs who were examined by interdisciplinary PU team and were followed up for at least two consecutive weeks were analysed. We found 9/11 PUs without a lower temperature at the wound edge did not develop undermining development, whereas 8/11 PUs with the lower temperature did develop undermining. The relative risk of undermining development after 1 week in PUs with the lower temperature was 4·00 (95% confidence intervals: 1·08-14·7). The sensitivity, specificity, positive predictive value and negative predictive value were 0·80, 0·75, 0·73 and 0·81, respectively. A thermal imaging assessment focusing on a lower temperature pattern at the wound edge may provide sufficient information to predict undermining development.

Diagnosis of breast tumor using thermal tomography q-r curve

Metabolic heat, the product following the metabolism of cells, is closely related to the pathological information of living organisms, which means there are strong connections between the heat distribution and the pathological state of the living organism. The mathematical function δ is introduced in the classical Pennes bioheat transfer equation as a point heat source, and by simplifying the boundary condition, a bioheat transfer model is established. Based on the temperature distribution of the human body surface, the q−r curve of heat intensity q varying with depth r is acquired while combining the fitting method of the Lorentz curve. According to 34,977 clinical confirmed cases and the corresponding classified statistics, diagnostic criteria (for breast diseases) for judging diseases by the q−r curve are proposed. The P -value of our statistics is <0.05 , which means our classified statistics are reliable. Six typical clinical examinations are performed, and the diagnosis results are very consistent with those of B-ultrasonic images, molybdenum target x-ray, and pathological examination, which suggests that the method of diagnosing diseases with a q−r curve has very good prospects for application. It is radiation free and noninvasive to the human body.

Q-r curve of thermal tomography and its clinical application on breast tumor diagnosis

Heat is the product following the metabolism of cells, and the metabolism is closely related with the pathological information of living organism. So, there are strong ties between the heat distribution and the pathological state in living organism. In this paper, the mathematical function δ is introduced in the classical Pennes bio-heat transfer equation as the point heat source. By simplifying the boundary conditions, a novel bio-heat transfer model is established and solved in a spherical coordinate system. Based on the temperature distribution of human body surface, the information of heat source is mined layer by layer, and the corresponding q-r curve of heat intensity varying with depth is acquired combining the fitting method of Lorentz curve. According to a large number of clinical confirmed cases and statistics, the diagnostic criteria judging diseases by q-r curve are proposed. Five typical clinical practices are performed and four of the diagnosis results are very consistent with those of molybdenum target (MT) X-ray, B-ultrasonic images and pathological examination, one gives the result of early stage malignant tumor that MT X-ray and B-ultrasonic can't check out. It is a radiation-free green method with noninvasive diagnostic procedure and accurate diagnosis result.

Effects of the selective glucocorticoid receptor modulator compound A on bone metabolism and inflammation in male mice with collagen-induced arthritis

Glucocorticoids (GCs) are potent drugs to treat rheumatoid arthritis but exert adverse skeletal effects. Compound A (CpdA) is a selective GC receptor modulator with an improved risk/benefit profile in mouse models of inflammation and bone loss. Here we tested whether CpdA also exerts bone-sparing effects under proinflammatory circumstances using the collagen-induced arthritis model, a murine model of rheumatoid arthritis. CpdA decreased disease activity, paw swelling, and the paw temperature by 43%, 12%, and 7%, respectively, but was less potent than dexamethasone (DEX), which reduced these parameters by 72%, 22%, and 10%, respectively. Moreover, T cells isolated from CpdA- and DEX-treated animals were less active based on proliferation rates after challenge with type II collagen and produced smaller amounts of interferon-γ and TNF as compared with T cells from PBS-treated mice. Histological assessment of the joints confirmed the weaker potency of CpdA as compared with DEX in preventing infiltration of inflammatory cells, induction of osteoclastogenesis, and destruction of articular cartilage. Due to the lack of GC-susceptible arthritis models, we were not able to fully address the bone-sparing potential of CpdA in inflammatory conditions. Nevertheless, the bone formation marker procollagen type 1 N-terminal peptide, a surrogate marker for GC-mediated suppression of bone formation, was significantly decreased by DEX in arthritic mice but not by CpdA. Our data indicate that CpdA moderately suppresses inflammation, whereas the concurrent effects on bone remain unknown. In light of its narrow therapeutic range, CpdA may be more useful as a molecular tool for dissecting GC actions rather than a therapeutic agent.

In vivo molecular imaging of experimental joint inflammation by combined (18)F-FDG positron emission tomography and computed tomography

Introduction

The purpose of this work was to establish and validate combined small animal positron emission tomography - computed tomography (PET/CT) as a new in vivo imaging method for visualisation and quantification of joint inflammation.

Methods

Signalling of radioisotope ¹⁸F labelled Fluorodeoxyglucose (¹⁸F-FDG) injected in mice with glucose-6-phosphate isomerase (G6PI)-induced arthritis was analysed by PET/CT. Accumulation of ¹⁸F-FDG in tissue was quantified by PET measurement, whereas high definition CT delivered anatomical information. The fusion of both images revealed in detail spatial and temporal distribution and metabolism of ¹⁸F-FDG.

Results

A distinct ¹⁸F-FDG signal could be measured by PET in carpal and tarsal joints, from mice with early or established arthritis. In contrast, no accumulation of ¹⁸F-FDG was detectable before arthritis onset. Comparison of ¹⁸F-FDG joint uptake with histopathological evaluation revealed a significant correlation of both methods.

Conclusions

Small animal PET/CT using ¹⁸F-FDG is a feasible method for monitoring and, more importantly, quantitative assessment of inflammation in G6PI-arthritis. Since it is possible to perform repeated non-invasive measurements in vivo, not only numbers of animals in preclinical studies can markedly be reduced by this method, but also longitudinal studies come into reach, e. g. for individual flare-up reactions or monitoring therapy response in progressive arthritis.

Gait changes precede overt arthritis and strongly correlate with symptoms and histopathological events in pristane-induced arthritis

INTRODUCTION

Pristane-induced arthritis (PIA) in the rat has been described as an animal model of inflammatory arthritis which exhibits features similar to rheumatoid arthritis in humans, such as a chronic, destructive, and symmetrical involvement of peripheral joints. However, so far little is known about the earliest inflammatory events and their influence on locomotor behaviour during the course of PIA. To investigate this issue a detailed analysis of the pathologic changes occurring during the prodromal and early stages of PIA was performed.

METHODS

Arthritis was induced in DA.rats by injection of 150 microl 2,6,10,4-tetramethyl-pentadecane (pristane) at the base of the tail and changes in locomotor behaviour of the affected paws were monitored using the CatWalk quantitative gait analysis system. The pathologic events occurring in the joints of pristane-injected animals were studied before onset, at onset, and during acute phase of arthritis by histological methods.

RESULTS

Gait analysis revealed that changes in locomotion such as reduced paw print areas and stance phase time are already apparent before the onset of clinically discernible arthritis symptoms (erythema, paw swelling) and correlate with PIA scores. In agreement with these findings, inflammatory tenosynovitis could be observed by histology already before the onset of erythema and swelling of the respective paws. In the most heavily affected rats also irregularities in step sequence patterns occurred A kinetic analysis of clinical and histological findings demonstrated that gait changes precede the pathological changes occurring during the acute phase of pristane-induced arthritis.

CONCLUSIONS

Gait analysis allows for pinpointing the initial inflammatory changes in experimental arthritis models such as pristane-induced arthritis. Analysis of early clinically relevant symptoms in arthritis models may facilitate the search for novel therapeutics to interfere with pain, inflammation and joint destruction in patients suffering from inflammatory arthritis.

The application of infrared thermography in the assessment of patients with coccygodynia before and after manual therapy combined with diathermy

OBJECTIVE

This study examines the potential usefulness of a novel thermal imaging technique in the assessment of local physiologic responses before and after conservative therapies for coccygodynia.

METHODS

Patients with coccygodynia were selected on the basis of detailed history taking, clinical examination, and dynamic series radiography. They underwent therapeutic modalities consisting of 6 to 8 sessions of manual medicine treatments (massage of the levators followed by Maigne's manipulative technique) and external physiotherapy (short-wave diathermy) 3 times a week for 8 weeks. We performed the assessments with numeric pain rating scale (NPRS) and infrared thermography (IRT) before treatment and at 12 weeks.

RESULTS

A total of 53 patients (6 males and 47 females) ranging from 18 to 71 years of age and clinically diagnosed with coccygodynia received the full course of therapy and assessments. There were significant differences in both NPRS and surface temperature obtained by IRT in the 12-week follow-up (P < .05). The correlation between NPRS improvement and temperature decrement was significantly high (r = 0.67, P < .01).

CONCLUSIONS

The study shows that IRT can objectively show the decrement of surface temperatures correlating with changes in subjective pain intensity after treatment of coccygodynia. With the advantages of being painless, noninvasive, and easy to repeat, IRT appears to be useful as a quantifiable tool for monitoring the dynamics of the disease activity in coccygodynia.

Ultrasonographic and thermographic screening for latent inflammation in diabetic foot callus

AIMS

Inflammation within the diabetic foot callus may be an earliest, predicting symptom of foot ulcer developing later. The purpose of this study was to identify latent inflammation within the foot callus using thermography and ultrasonography, and to investigate relationship between the inflammatory findings in callus and presence or absence of diabetes.

METHODS

This was a cross-sectional study of 60 cases with asymptomatic foot callus; the 30 diabetic patients and the 30 non-diabetic matched volunteers. Inflammation was defined using physiological imaging techniques; as skin temperature elevation in thermography and low echoic lesion in ultrasonography.

RESULTS

Sixty-three and ninety-four calli were observed in the diabetic and non-diabetic groups, respectively. The inflammation signs were detected by both of the two techniques in 10% of the calli in the diabetic group. No inflammation was noted in the non-diabetic group (p=0.014).

CONCLUSIONS

The inflammation signs presented here were specifically observed in the diabetic group. We consider that the physiological imaging techniques may be valuable screening tools for potential risk of diabetic foot ulcers.

Use of a portable thermal imaging unit as a rapid, quantitative method of evaluating inflammation and experimental arthritis

INTRODUCTION

Thermal imaging has been utilized, both preclinically and clinically, as a tool for assessing inflammation and arthritis. However, previous studies have employed large, relatively immobile devises to obtain the thermal signature of the tissue of interest. The present study describes the characterization of a hand-held thermal imaging device in a preclinical model of general inflammation and a model of rheumatoid arthritis (RA).

METHODS

A hand-held ThermoView Ti30 portable thermal imager was utilized to detect the temporal changes in thermal signatures in rat model of carrageenan-induced paw edema (CFE) and a model of collagen-induced arthritis (CIA). In both in vivo models, the kinetics of the thermal changes were correlated to footpad swelling. In addition, the CFE model was utilized to examine the ability of this technology to delineate pharmacodynamic changes in thermal signature in response to the non-steroidal anti-inflammatory drug indomethacin (10 mg/kg; p.o.).

RESULTS

Thermal analysis of rat paws in the CFE model demonstrated a significant increase in the mean temperature difference between the inflamed and contralateral control paw by two hours post-carrageenan (8.3 +/-0.5 degrees F). Indomethacin significantly decreased the mean temperature difference in treated animals as compared to vehicle. In the rat CIA model, increases in footpad temperature, as determined by thermal imaging, were significantly elevated by Day 11 and remained elevated throughout the duration of the 28 day protocol. Thermal changes were also found to precede increases in footpad edema (swelling).

DISCUSSION

The results of this study demonstrate that the hand-held thermal imaging technology represents a rapid, highly-reproducible method by which to quantitate the degree of inflammation in rat models of general inflammation and rheumatoid arthritis. The ability to detect pharmacodynamic responses in paw temperature suggests that this technology may be a useful tool for the development of pharmacologic interventions for the treatment inflammation-related pathologies.

Three-dimensional and thermal surface imaging produces reliable measures of joint shape and temperature: a potential tool for quantifying arthritis

Introduction

The assessment of joints with active arthritis is a core component of widely used outcome measures. However, substantial variability exists within and across examiners in assessment of these active joint counts. Swelling and temperature changes, two qualities estimated during active joint counts, are amenable to quantification using noncontact digital imaging technologies. We sought to explore the ability of three dimensional (3D) and thermal imaging to reliably measure joint shape and temperature.

Methods

A Minolta 910 Vivid non-contact 3D laser scanner and a Meditherm med2000 Pro Infrared camera were used to create digital representations of wrist and metacarpalphalangeal (MCP) joints. Specialized software generated 3 quantitative measures for each joint region: 1) Volume; 2) Surface Distribution Index (SDI), a marker of joint shape representing the standard deviation of vertical distances from points on the skin surface to a fixed reference plane; 3) Heat Distribution Index (HDI), representing the standard error of temperatures. Seven wrists and 6 MCP regions from 5 subjects with arthritis were used to develop and validate 3D image acquisition and processing techniques. HDI values from 18 wrist and 9 MCP regions were obtained from 17 patients with active arthritis and compared to data from 10 wrist and MCP regions from 5 controls. Standard deviation (SD), coefficient of variation (CV), and intraclass correlation coefficients (ICC) were calculated for each quantitative measure to establish their reliability. CVs for volume and SDI were <1.3% and ICCs were greater than 0.99.

Results

Thermal measures were less reliable than 3D measures. However, significant differences were observed between control and arthritis HDI values. Two case studies of arthritic joints demonstrated quantifiable changes in swelling and temperature corresponding with changes in symptoms and physical exam findings.

Conclusion

3D and thermal imaging provide reliable measures of joint volume, shape, and thermal patterns. Further refinement may lead to the use of these technologies to improve the assessment of disease activity in arthritis.

Contribution of genetic studies in rodent models of autoimmune arthritis to understanding and treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic and potentially debilitating autoimmune disease. While novel therapies have emerged in recent years, disease remission is rarely achieved. RA is a complex trait, and the identifying of its susceptibility and severity genes has been anticipated to generate new targets for therapeutic intervention. However, finding those genes and understanding their function has been a challenging task. Studies in rodent intercrosses and congenics generated from inbred strains have been an important complementary strategy to identify arthritis genes, and understand how they operate to regulate disease. Furthermore, these new rodent arthritis genes will be new targets for therapeutic interventions, and will identify new candidate genes or candidate pathways for association studies in RA. In this review-opinion article I discuss RA genetics, difficulties involved in gene identification, and how rodent models can facilitate (1) the discovery of both arthritis susceptibility and severity genes, (2) studies of gene-environment interactions, (3) studies of gene-gender interactions, (4) epistasis, (5) functional characterization of the specific genes, (6) development of novel therapies and (7) how the information generated from rodent studies will be useful to understanding and potentially treating RA.

Decreased core temperature and increased beta(3)-adrenergic sensitivity in diabetes-prone BB rats

BACKGROUND

Diabetes-prone (DP) congenic DR.lyp/lyp BioBreeding (BB) rats all develop Type 1 diabetes between 50 and 81 days of age, while DR.lyp/+ or DR.+/+ BB rats are diabetes resistant (DR). The DP rats display reduced weight gain prior to developing hyperglycemia, implying that metabolic events may precede diabetes onset. We tested the hypothesis that temperature measurements could serve as a physiological marker for the impending onset of hyperglycemia.

METHODS

Prior to the onset of hyperglycemia, brain, lower back, and intrascapular brown adipose tissue temperatures were analyzed by thermal signature analysis, which measures infrared emission from tissues. A thermocoupled rectal probe measured core temperature. In addition we performed a beta(3)-adrenergic receptor challenge test with the beta(3)-adrenergic receptor agonist BRL37344.

RESULTS

DP rats displayed lower core temperature than DR rats prior to the onset of hyperglycemia. No temperature difference was detected in brain, lower back, or intrascapular brown adipose tissue between DP and DR rats. The beta(3)-adrenergic challenge showed that the rate of temperature increase after administration of BRL37344 was significantly higher (0.005 +/- 0.002 degrees C/min) in DP than in DR rats (P = 0.044).

CONCLUSIONS

These studies reveal that the prediabetic DP rats fail to maintain core temperature and that they display increased sensitivity to heat production induced by a beta(3)-adrenergic receptor agonist. These studies suggest that body temperature as a measure of metabolic dysregulation is altered in the prediabetic DP rat prior to the onset of hyperglycemia.

The arthritis severity quantitative trait loci Cia4 and Cia6 regulate neutrophil migration into inflammatory sites and levels of TNF-alpha and nitric oxide

Neutrophils are required for the development of arthritis, and their migration into the synovial tissue coincides with the onset of clinical disease. Synovial neutrophil numbers also correlate with rheumatoid arthritis disease activity and severity. We hypothesized that certain arthritis severity genes regulate disease via the regulation of neutrophil migration into the joint. This hypothesis was tested in the synovial-like air pouch model injected with carrageenan using arthritis-susceptible DA and arthritis-resistant F344 rats. DA had nearly 3-fold higher numbers of exudate neutrophils compared with F344 (p < 0.001). Five DA.F344(QTL) strains congenic for severity loci and protected from autoimmune arthritis were studied. Only DA.F344(Cia4) (chromosome 7) and DA.F344(Cia6) (chromosome 8) congenics had significantly lower exudate neutrophil counts compared with DA. TNF-alpha levels were 2.5-fold higher in DA exudates as compared with F344 exudates, and that difference was accounted for by the Cia4 locus. Exudate levels of NO, a known inhibitor of neutrophil chemotaxis, were higher in F344, compared with DA, and that difference was accounted for by Cia6. This is the first time that non-MHC autoimmune arthritis loci are found to regulate three central components of the innate immune response implicated in disease pathogenesis, namely neutrophil migration into an inflammatory site, as well as exudate levels of TNF-alpha and NO. These observations underscore the importance of identifying the Cia4 and Cia6 genes, and suggest that they should generate useful novel targets for development of new therapies.

Cia25 on rat chromosome 12 regulates severity of autoimmune arthritis induced with pristane and with collagen

BACKGROUND

A genomewide scan in a DA x ACI F2 intercross studied for collagen-induced arthritis (CIA) identified the severity quantitative trait locus Cia25 on rat chromosome 12. Cia25 co-localises with loci regulating several forms of autoimmune diseases in rats, mice and humans, suggesting a common gene.

OBJECTIVE

To characterise the effects of Cia25 on severity of arthritis in congenic rats.

METHODS

DA.ACI(Cia25) congenic rats were constructed according to a genotype-guided strategy, and tested for pristane-induced arthritis (PIA) and CIA, induced with rat type II collagen (CII). A well-established scoring system previously shown to correlate with histological damage, including cartilage and bone erosions, synovial hyperplasia and synovial inflammation, was used.

RESULTS

The introgression of ACI alleles at Cia25 into DA background, as in DA.ACI(Cia25) rats, was enough to significantly reduce arthritis severity by 60% in PIA and by 40% in CIA, both in males and females compared with DA rats of the same sex. Levels of IgG anti-CII in male DA.ACI(Cia25) rats were 83% lower than in male DA. Levels of anti-CII in females were not affected by the congenic interval.

CONCLUSIONS

Cia25 contains a gene that regulates disease severity in two distinct models of autoimmune arthritis. Although both genders were protected in arthritis studies, only male congenic rats had a dramatic reduction in levels of anti-CII, suggesting the possibility of a second arthritis gene in this interval that operates via the regulation of autoantibodies in a sex-specific manner. The identification of the gene(s) accounting for Cia25 is expected to generate novel prognostic biomarkers and targets for therapy.

The arthritis severity quantitative trait locus Cia7 regulates neutrophil migration into inflammatory sites

Neutrophils are required for the development of arthritis in rodents, and are the predominant cell in the synovial fluid of active rheumatoid arthritis. We hypothesized that neutrophil migration into the inflammed joint is genetically regulated. In addition, this genetic regulation would be accounted for by one of the arthritis loci that we have previously identified in an intercross between arthritis-susceptible DA and arthritis-resistant ACI rats studied for collagen-induced arthritis. We used the synovial-like air pouch model injected with carrageenan, and tested DA, ACI, and four congenic strains. ACI exudates had a significantly lower number of neutrophils compared with DA. Transfer of DA alleles at Cia7 into the ACI background, as in ACI.DA(Cia7) congenics, was enough to increase exudate neutrophil numbers to levels identical to DA, and this locus accounted for the difference between parental strains. None of the other congenic intervals explained the differences in exudate neutrophil counts. In conclusion, we have identified a novel function for Cia7, and determined that it regulates neutrophil migration into a synovial-like inflammatory site. Our data revealed no intrinsic defect in neutrophil responses to chemotactic agents, and suggest that Cia7 regulates an as yet unidentified factor central to neutrophil recruitment into inflammed tissues.

Cia27 is a novel non-MHC arthritis severity locus on rat chromosome 10 syntenic to the rheumatoid arthritis 17q22–q25 locus

Cia27 on rat chromosome 10 is a collagen-induced arthritis (CIA) severity quantitative trait locus originally identified in a study of (DA x ACI) F2. As an initial step towards the positional cloning of the Cia27 gene, a 17 cM (21 Mb) interval from the DA strain (arthritis-susceptible) containing the two-logarithm of odds support interval comprising Cia27 was introgressed into the ACI (arthritis-resistant) background through genotype-guided congenic breeding. ACI.DA(Cia27) congenics developed a significantly more severe form of arthritis (CIA), with a 5.9-fold increase in median arthritis severity index, a parameter known to correlate with synovial inflammation, and cartilage and bone erosions, compared with ACI (P< or =0.001). The arthritis severity enhancing effect could be detected from day 21 onwards. Rats heterozygous at the congenic interval developed a disease similar to ACI rats, suggesting that DA alleles operate in a recessive manner. Levels of autoantibodies anti-rat type II collagen did not correlate with arthritis severity. Synovial tissue mRNA levels of interleukin-1beta (IL-1beta) were significantly increased in ACI.DA(Cia27) congenics compared with ACI. These results demonstrate that Cia27 harbors a novel arthritis severity regulatory gene. The identification of this gene should facilitate the identification of the rheumatoid arthritis gene mapped to the human syntenic region on chromosome 17q22-q25.