Reducing cardiovascular risk with immunomodulators: a randomised active comparator trial among patients with rheumatoid arthritis.

OBJECTIVE: Recent large-scale randomised trials demonstrate that immunomodulators reduce cardiovascular (CV) events among the general population. However, it is uncertain whether these effects apply to rheumatoid arthritis (RA) and if certain treatment strategies in RA reduce CV risk to a greater extent. METHODS: Patients with active RA despite use of methotrexate were randomly assigned to addition of a tumour necrosis factor (TNF) inhibitor (TNFi) or addition of sulfasalazine and hydroxychloroquine (triple therapy) for 24 weeks. Baseline and follow-up 18F-fluorodeoxyglucose-positron emission tomography/CT scans were assessed for change in arterial inflammation, an index of CV risk, measured as an arterial target-to-background ratio (TBR) in the carotid arteries and aorta. RESULTS: 115 patients completed the protocol. The two treatment groups were well balanced with a median age of 58 years, 71% women, 57% seropositive and a baseline disease activity score in 28 joints of 4.8 (IQR 4.0, 5.6). Baseline TBR was similar across the two groups. Significant TBR reductions were observed in both groups-ΔTNFi: -0.24 (SD=0.51), Δtriple therapy: -0.19 (SD=0.51)-without difference between groups (difference in Δs: -0.02, 95% CI -0.19 to 0.15, p=0.79). While disease activity was significantly reduced across both treatment groups, there was no association with change in TBR (ß=0.04, 95% CI -0.03 to 0.10). CONCLUSION: We found that addition of either a TNFi or triple therapy resulted in clinically important improvements in vascular inflammation. However, the addition of a TNFi did not reduce arterial inflammation more than triple therapy. TRIAL REGISTRATION NUMBER: NCT02374021.

Testing the Effects of Disease-Modifying Antirheumatic Drugs on Vascular Inflammation in Rheumatoid Arthritis: Rationale and Design of the TARGET Trial.

Individuals with rheumatoid arthritis (RA) are at increased risk for atherosclerotic cardiovascular disease (ASCVD) events relative to the general population, potentially mediated by atherosclerotic plaques that are more inflamed and rupture prone. We sought to address whether RA immunomodulators reduce vascular inflammation, thereby reducing ASCVD risk, and whether such reduction depends on the type of immunomodulator. The TARGET (Treatments Against RA and Effect on 18-Fluorodeoxyglucose [18 F-FDG] Positron Emission Tomography [PET]/Computed Tomography [CT]) trial (NCT02374021) will enroll 150 patients with RA with active disease and an inadequate response to methotrexate. Participants will be randomized to add either a tumor necrosis factor (TNF) inhibitor (etanercept or adalimumab) or sulfasalazine and hydroxychloroquine to their background methotrexate. Participants will undergo full-body 18 F-FDG-labelled PET scanning at baseline and after 6 months. Efficacy and safety evaluations will occur every 6 weeks, with therapy modified in a treat-to-target approach. The primary outcome is the comparison of change in arterial inflammation in the wall of the aorta and carotid arteries between the randomized treatment groups, specifically, the change in the mean of the maximum target-to-background ratio of arterial 18 F-FDG uptake in the most diseased segment of either the aorta and carotid arteries. A secondary analysis will compare the effects of achieving low disease activity or remission with those of moderate to high disease activity on vascular inflammation. The TARGET trial will test, for the first time, whether RA treatments reduce arterial inflammation and whether such reduction differs according to treatment strategy with either TNF inhibitors or a combination of nonbiologic disease-modifying antirheumatic drugs.

Outcomes of a Mobile App to Monitor Patient-Reported Outcomes in Rheumatoid Arthritis: A Randomized Controlled Trial.

OBJECTIVE: To examine the effects of a smartphone application (app) to monitor longitudinal electronic patient-reported outcomes (ePROs) on patient satisfaction and disease activity in patients with rheumatoid arthritis (RA). METHODS: We conducted a 6-month randomized controlled trial of care coordination along with an app (intervention) versus care coordination alone (control) in 191 RA patients. Participants in the intervention group were prompted to provide information daily using ePROs. In both the intervention and control groups, a care coordinator contacted participants at 6 and 18 weeks to assess for flares. The main outcome measures were the global satisfaction score from the Treatment Satisfaction Questionnaire for Medication (TSQM), the score from the Perceived Efficacy in Patient-Physician Interactions (PEPPI) Questionnaire, and the Clinical Disease Activity Index (CDAI) score. RESULTS: Groups were similar at baseline. The median TSQM score at 6 months was 83.3 in both groups, and the median PEPPI score at 6 months was 50 in both groups. The median CDAI score at 6 months was 8 in the intervention group versus 10 in the control group. No statistically significant group differences in the medians of TSQM, PEPPI, or CDAI scores at 6 months were detected. Of the 67 intervention participants who completed the exit survey, 90% rated their likelihood of recommending the app as ≥7 of 10. Of the 11 physicians who completed the exit survey, 73% agreed/strongly agreed that they wanted to continue offering the app to patients. CONCLUSION: A mobile app designed to collect ePRO data on RA symptoms did not significantly improve patient satisfaction or disease activity compared to care coordination alone. However, both patients and physicians reported positive experiences with the app.

Patient adherence with a smartphone app for patient-reported outcomes in rheumatoid arthritis.

OBJECTIVES: Electronic patient-reported outcomes (ePROs) transmitted digitally allow patients to communicate with their clinicians and track the activity of chronic diseases, such as RA. Several ePRO smartphone apps have been developed in rheumatology, yet few data have been reported regarding patient adherence. We developed a PRO app for RA and assessed adherence over 6 months. METHODS: We developed an app to deliver daily assessments to participants (RA App v.1.0). The app was tested as part of a randomized controlled trial examining potential clinical benefits. The current analyses focus on the adherence to the ePRO app for patients randomized to receive the app. We recruited RA patients from an academic rheumatology practice in the USA. Patients randomized to receive the app received daily notifications regarding ePROs. We examined adherence to the PRO questionnaires over the 6-month study and examined factors related to adherence. RESULTS: Seventy-eight patients received the app and have data included in these analyses: 63 (80.7%) were female, mean age was 55.2 years, 71% had attended college or beyond, and the mean Clinical Disease Activity Index at baseline was 9.7 (low disease activity). Median adherence to the daily questions was 79% (interquartile range 48-90%). Significant predictors of increased adherence were age ≥65 (P = 0.03) and low baseline Clinical Disease Activity Index (P = 0.02). CONCLUSION: We developed and tested an ePRO app for RA over a 6-month study. Adherence to the app was strong. There was correlation between older age and better disease control and increased adherence. TRIAL REGISTRATION: ClinicalTrials.gov, https://clinicaltrials.gov/, NCT02822521.

Adverse Effects of Low-Dose Methotrexate in a Randomized Double-Blind Placebo-Controlled Trial: Adjudicated Hematologic and Skin Cancer Outcomes in the Cardiovascular Inflammation Reduction Trial.

OBJECTIVE: Low-dose methotrexate (LD-MTX), a cornerstone in the treatment of rheumatoid arthritis, is associated with a moderately increased risk of anemia, leukopenia, and skin cancers, but the risks of myelosuppression and malignancy during LD-MTX use remain incompletely described. We examined the risks of cytopenias and skin cancers among patients taking LD-MTX versus placebo in a large randomized controlled trial (RCT). METHODS: We prespecified secondary analyses of a double-blind, placebo-controlled RCT that included adults with known cardiovascular disease and diabetes or metabolic syndrome in the United States and Canada. Subjects were randomly allocated to LD-MTX (20 mg/week maximum) or placebo. All subjects received folic acid (1 mg daily for 6days/week). We assessed the frequency of blindly adjudicated hematologic and malignant adverse events (AEs). RESULTS: A total of 2391 subjects were randomized to LD-MTX (mean dosage 14.9 mg/week), and 2395 were randomized to placebo. During follow-up, in the LD-MTX arm, simultaneous two-line cytopenias (n = 92 [3.9%]) or pancytopenia (n = 13 [0.54%]) were infrequent. Pancytopenia developed as soon as 4 months and as late as 3.5 years after beginning LD-MTX, though the latter subject had been recently diagnosed with multiple myeloma. Overall skin cancer risk was increased in users of LD-MTX compared with users of placebo, which driven largely by a statistically significant increased risk of squamous cell skin cancer (hazard ratio [HR] 3.31; 95% confidence interval [CI] 1.63-6.71). Melanoma was increased in LD-MTX, but this was not statistically significant (HR 2.33; 95% CI 0.60-9.01). CONCLUSIONS: Among subjects using LD-MTX, simultaneous two-line cytopenias and pancytopenia were uncommon. We found more cases of skin cancer, particularly squamous cell carcinomas, in the LD-MTX arm than the placebo arm.

Adverse Effects of Low-Dose Methotrexate: A Randomized Trial.

Background: Low-dose methotrexate (LD-MTX) is the most commonly used drug for systemic rheumatic diseases worldwide and is the recommended first-line agent for rheumatoid arthritis. Despite extensive clinical use for more than 30 years, few data on adverse event (AE) rates derive from randomized, placebo-controlled trials, where both causality and magnitude of risk can be inferred. Objective: To investigate AE rates, risk, and risk differences comparing LD-MTX versus placebo. Design: Prespecified secondary analyses of a double-blind, placebo-controlled, randomized trial. (ClinicalTrials.gov: NCT01594333). Setting: North America. Participants: Adults with known cardiovascular disease and diabetes or metabolic syndrome. Intervention: Random allocation to LD-MTX (≤20 mg/wk) or placebo. All participants received folic acid, 1 mg/d, 6 days per week. Measurements: Risks for specific AEs of interest, as well as for all AEs, were compared across treatment groups after blinded adjudication. Results: After an active run-in period, 6158 patients were enrolled and 4786 randomly assigned to a group; median follow-up was 23 months and median dosage 15 mg/wk. Among the randomly assigned participants, 81.2% were male, median age was 65.7 years, and median body mass index was 31.5 kg/m2. Of 2391 participants assigned to LD-MTX, 2080 (87.0%) had an AE of interest, compared with 1951 of 2395 (81.5%) assigned to placebo (hazard ratio [HR], 1.17 [95% CI, 1.10 to 1.25]). The relative hazards of gastrointestinal (HR, 1.91 [CI, 1.75 to 2.10]), pulmonary (HR, 1.52 [CI, 1.16 to 1.98]), infectious (HR, 1.15 [CI, 1.01 to 1.30]), and hematologic (HR, 1.15 [CI, 1.07 to 1.23]) AEs were elevated for LD-MTX versus placebo. With the exception of increased risk for skin cancer (HR, 2.05 [CI, 1.28 to 3.28]), the treatment groups did not differ in risk for other cancer or mucocutaneous, neuropsychiatric, or musculoskeletal AEs. Renal AEs were reduced in the LD-MTX group (HR, 0.85 [CI, 0.78 to 0.93]). Limitation: The trial was done in patients without rheumatic disease who tolerated LD-MTX during an active run-in period. Conclusion: Use of LD-MTX was associated with small to moderate elevations in risks for skin cancer and gastrointestinal, infectious, pulmonary, and hematologic AEs, whereas renal AEs were decreased. Primary Funding Source: National Institutes of Health.

Mobile Apps for Individuals With Rheumatoid Arthritis: A Systematic Review.

BACKGROUND: Mobile health applications (apps) have the potential to help individuals with chronic illnesses learn about, monitor, and manage their condition, but these apps are largely unexamined, with the state and direction of development unclear. OBJECTIVE: We performed a systematic review of publicly available apps, directed toward individuals with rheumatoid arthritis (RA); described their current features; and determined areas of unmet need. METHODS: We searched the iTunes and Google Play App Stores for the term "arthritis" and reviewed the descriptions of these apps for specific mentions of RA. Applications that met inclusion criteria were downloaded and reviewed. Using a set of quality measures identified from literature review, we assessed each app for 4 features: basic characteristics, content source, functionality, and security. Frequencies for each feature were recorded, and percentages were calculated. RESULTS: Twenty apps intended for use by RA patients were identified in December 2016. Fifty percent of apps (n = 10) offered only symptom tracking. Five (20%) provided only information about RA, and 5 (20%) engaged patients by providing both symptom tracking and educational information. Fewer than 50% of apps provided means to contact health care providers or link to an online community, and only 6 (30%) offered security protection for the user. CONCLUSIONS: Most current RA apps do not provide a comprehensive experience for individuals with RA. Areas for optimization include the implementation of smartphone accessibility features and secure methods of protecting individual health information.

A Novel Mobile App and Population Management System to Manage Rheumatoid Arthritis Flares: Protocol for a Randomized Controlled Trial.

BACKGROUND: Rheumatoid arthritis flares have a profound effect on patients, causing pain and disability. However, flares often occur between regularly scheduled health care provider visits and are, therefore, difficult to monitor and manage. We sought to develop a mobile phone app combined with a population management system to help track RA flares between visits. OBJECTIVE: The objective of this study is to implement the mobile app plus the population management system to monitor rheumatoid arthritis disease activity between scheduled health care provider visits over a period of 6 months. METHODS: This is a randomized controlled trial that lasts for 6 months for each participant. We aim to recruit 190 patients, randomized 50:50 to the intervention group versus the control group. The intervention group will be assigned the mobile app and be prompted to answer daily questionnaires sent to their mobile devices. Both groups will be assigned a population manager, who will communicate with the participants via telephone at 6 weeks and 18 weeks. The population manager will also communicate with the participants in the intervention group if their responses indicate a sustained increase in rheumatoid arthritis disease activity. To assess patient satisfaction, the primary outcomes will be scores on the Treatment Satisfaction Questionnaire for Medication as well as the Perceived Efficacy in Patient-Physician Interactions questionnaire at 6 months. To determine the effect of the mobile app on rheumatoid arthritis disease activity, the primary outcome will be the Clinical Disease Activity Index at 6 months. RESULTS: The trial started in November 2016, and an estimated 2.5 years will be necessary to complete the study. Study results are expected to be published by the end of 2019. CONCLUSIONS: The completion of this study will provide important data regarding the following: (1) the assessment of validated outcome measures to assess rheumatoid arthritis disease activity with a mobile app between routinely scheduled health care provider visits, (2) patient engagement in monitoring their condition, and (3) communication between patients and health care providers through the population management system. TRIAL REGISTRATION: ClinicalTrials.gov NCT02822521, http://clinicaltrials.gov/ct2/show/NCT02822521 (Archived by WebCite at http://www.webcitation.org/6xed3kGPd).

Identification of monosodium urate crystal deposits in patients with asymptomatic hyperuricemia using dual-energy CT.

OBJECTIVES: Dual-energy CT (DECT) scan is a sensitive and specific tool used to visualise and quantify monosodium urate (MSU) crystal deposits in the joints. Few studies have examined MSU crystal deposits in patients with asymptomatic hyperuricemia (ie, hyperuricemia in the absence of gout) using DECT. METHODS: We conducted a prospective, non-interventional cross-sectional study to detect MSU crystal deposits on DECT scans among patients with asymptomatic hyperuricemia. We also examined patient factors associated with subclinical MSU crystal deposits. Out of 130 subjects aged ≥40 years with metabolic syndrome screened for serum uric acid (sUA) levels ≥6.5 mg/dL, 46 underwent a foot/ankle DECT scan. RESULTS: The mean age of the study participants was 62 (±8) years, 41% were men and the mean sUA level was 7.8 (±1.0) mg/dL. Seven (15%) of 46 patients had MSU crystal deposits on DECT with a mean total volume of 0.13 (±0.14) cm3. In the univariable logistic regression analysis, older age had a significant association with presence of MSU crystal deposits (OR 1.20, 95% CI 1.03 to 1.39), but sUA did not (OR 1.36, 95% CI 0.63 to 2.95). In the univariable analysis, sUA levels showed a trend towards a modest linear association (ß=0.11, P=0.09) with total volume of MSU crystal deposits. CONCLUSIONS: Fifteen per cent of patients with asymptomatic hyperuricemia had subclinical MSU crystal deposits on foot/ankle DECT scans. Older age, but not sUA, was significantly associated with presence of subclinical MSU crystal deposits among patients with asymptomatic hyperuricemia. Clinical significance of these subclinical MSU crystal deposits needs to be determined.

Asymptomatic hyperuricemia and coronary flow reserve in patients with metabolic syndrome.

BACKGROUND: Patients with metabolic syndrome (MetS) are at increased risk of asymptomatic hyperuricemia (i.e., elevated serum uric acid (SUA) level without gout) and cardiovascular disease. We conducted a cross-sectional study to examine associations between SUA levels and coronary flow reserve and urate deposits in carotid arteries in patients with asymptomatic hyperuricemia and MetS. METHODS: Adults aged ≥40 years with MetS and SUA levels ≥6.5 mg/dl, but no gout, were eligible. Using a stress myocardial perfusion positron emission tomography (PET), we assessed myocardial blood flow (MBF) at rest and stress and calculated coronary flow reserve (CFR). CFR < 2.0 is considered abnormal and associated with increased cardiovascular risk. We also measured insulin resistance by homeostatic model assessment (HOMA-IR) method and urate deposits using dual-energy CT (DECT) of the neck for the carotid arteries. RESULTS: Forty-four patients with the median age of 63.5 years underwent a blood test, cardiac PET and neck DECT scans. Median (IQR) SUA was 7.8 (7.1-8.4) mg/dL. The median (IQR) CFR was abnormally low at 1.9 (1.7-2.4) and the median (IQR) stress MBF was 1.7 (1.3-2.2) ml/min/g. None had urate deposits in the carotid arteries detected by DECT. In multivariable linear regression analyses, SUA had no association with CFR (ß = - 0.12, p = 0.78) or stress MBF (ß = - 0.52, p = 0.28). Among non-diabetic patients (n = 25), SUA was not associated with HOMA-IR (ß = 2.08, p = 0.10). CONCLUSIONS: Among MetS patients with asymptomatic hyperuricemia, we found no relationship between SUA and CFR, stress MBF, and insulin resistance. No patients had any DECT detectable subclinical urate deposition in the carotid arteries.

Investigating methotrexate toxicity within a randomized double-blinded, placebo-controlled trial: Rationale and design of the Cardiovascular Inflammation Reduction Trial-Adverse Events (CIRT-AE) Study.

BACKGROUND: The role of low dose methotrexate (LDM) in potential serious toxicities remains unclear despite its common use. Prior observational studies investigating LDM toxicity compared LDM to other active drugs. Prior placebo-controlled clinical trials of LDM in inflammatory conditions were not large enough to investigate toxicity. The Cardiovascular Inflammation Reduction Trial (CIRT) is an ongoing NIH-funded, randomized, double-blind, placebo-controlled trial of LDM in the secondary prevention of cardiovascular disease. We describe here the rationale and design of the CIRT-Adverse Events (CIRT-AE) ancillary study which aims to investigate adverse events within CIRT. DESIGN: CIRT will randomize up to 7000 participants with cardiovascular disease and no systemic rheumatic disease to either LDM (target dose: 15-20mg/week) or placebo for an average follow-up period of 3-5 years; subjects in both treatment arms receive folic acid 1mg daily for 6 days each week. The primary endpoints of CIRT include recurrent cardio vascular events, incident diabetes, and all-cause mortality, and the ancillary CIRT-AE study has been designed to adjudicate other clinically important adverse events including hepatic, gastrointestinal, respiratory, hematologic, infectious, mucocutaneous, oncologic, renal, neurologic, and musculoskeletal outcomes. Methotrexate polyglutamate levels and genome-wide single nucleotide polymorphisms will be examined for association with adverse events. SUMMARY: CIRT-AE will comprehensively evaluate potential LDM toxicities among subjects with cardiovascular disease within the context of a large, ongoing, double-blind, placebo-controlled trial. This information may lead to a personalized approach to monitoring LDM in clinical practice.

Using Cognitive Testing to Develop Items for Surveying Asian American Cancer Patients and Their Caregivers as a Pathway to Culturally Competent Care.

We report the results from cognitive interviews with Asian American patients and their caregivers. We interviewed seven caregivers and six patients who were all bilingual Asian Americans. The main goal of the cognitive interviews was to test a survey instrument developed for a study about perspectives of Asian American patients with advanced cancer who are facing decisions around end-of-life care. We were particularly interested to see whether items commonly used in White and Black populations are culturally meaningful and equivalent in Asian populations, primarily those of Chinese and Vietnamese ethnicity. Our exploration shows that understanding respondents' language proficiency, degree of acculturation, and cultural context of receiving, processing, and communicating information about medical care can help design questions that are appropriate for Asian American patients and caregivers, and therefore can help researchers obtain quality data about the care Asian American cancer patients receive.

Human C1-Inhibitor Suppresses Malaria Parasite Invasion and Cytoadhesion via Binding to Parasite Glycosylphosphatidylinositol and Host Cell Receptors.

Plasmodium falciparum-induced severe malaria remains a continuing problem in areas of endemicity, with elevated morbidity and mortality. Drugs targeting mechanisms involved in severe malaria pathology, including cytoadhesion of infected red blood cells (RBCs) to host receptors and production of proinflammatory cytokines, are still necessary. Human C1-inhibitor (C1INH) is a multifunctional protease inhibitor that regulates coagulation, vascular permeability, and inflammation, with beneficial effects in inflammatory disease models, including septic shock. We found that human C1INH, at therapeutically relevant doses, blocks severe malaria pathogenic processes by 2 distinct mechanisms. First, C1INH bound to glycan moieties within P. falciparum glycosylphosphatidylinositol (PfGPI) molecules on the parasite surface, inhibiting parasite RBC invasion and proinflammatory cytokine production by parasite-stimulated monocytes in vitro and reducing parasitemia in a rodent model of experimental cerebral malaria (ECM) in vivo. Second, C1INH bound to host CD36 and chondroitin sulfate A molecules, interfering with cytoadhesion of infected RBCs by competitive binding to these receptors in vitro and reducing sequestration in specific tissues and protecting against ECM in vivo. This study reveals that C1INH is a potential therapeutic antimalarial molecule able to interfere with severe-disease etiology at multiple levels through specific interactions with both parasite PfGPIs and host cell receptors.

The effect of C1 inhibitor on myocardial ischemia and reperfusion injury.

BACKGROUND: Activation of the complement system has been demonstrated to be an important mechanism in the mediation of myocardial ischemia and reperfusion (MIR) injury. C1 inhibitor (C1INH) has been shown to be beneficial in experimental MIR models. The underlying mechanism of this effect has been assumed to result primarily from inhibition of complement system activation. We recently demonstrated that C1INH plays a direct role in suppression of leukocyte transmigration in the mouse intestinal ischemia and reperfusion model. The purpose of this study was to investigate the mechanism of the beneficial effect of C1INH in mouse MIR model. METHODS: C57BL/6, C1INH-deficient (C1INH(-/-)), and C3-deficient mice (C3(-/-)) were subjected to 30-min (C57BL/6 and C1INH(-/-)) or 60-min (C3(-/-)) occlusion of the left anterior descending branch of the coronary artery followed by 4-h reperfusion. C1INH or reactive center cleaved inactive C1INH (iC1INH) was injected intravenously 5 min before reperfusion. RESULTS: Myocardial infarct size relative to the area at risk or relative to left ventricular area was significantly reduced in C1INH-treated wild-type, C1INH(-/-), and C3(-/-) mice compared with vehicle-treated mice. MIR induced an increase in myocardial polymorphonuclear neutrophil accumulation and plasma cardiac specific troponin I levels in vehicle-treated MIR mice, while C1INH treatment significantly attenuated these effects. iC1INH had a similar protective effect. CONCLUSIONS: These results suggested that C1INH prevented MIR injury in mice and that this cardioprotective effect may not solely result from complement inhibition, but might be also contributed by inhibiting leukocyte recruitment into ischemic tissue, an effect that is not mediated via protease inhibition.

C1 inhibitor, a multi-functional serine protease inhibitor.

C1 inhibitor (C1INH) is a serpin that regulates both complement and contact (kallikrein-kinin) system activation. It consists of a serpin domain that is highly homologous to other serpins and an amino terminal non-serpin mucin-like domain. Deficiency of C1INH results in hereditary angioedema, a disease characterised by episodes of angioedema of the skin or the mucosa of the gastrointestinal tract or the oropharynx. Although early data suggested that angioedema was mediated via complement system activation, the preponderance of the data indicate that bradykinin is the mediator. In the past few years, it has become apparent that C1INH has additional anti-inflammatory functions independent of protease inhibition. These include interactions with leukocytes that may result in enhanced phagocytosis, with endothelial cells via E- and P-selectins that interfere with leukocyte rolling and in turn results in suppression of transmigration of leukocytes across the endothelium, and interactions with extracellular matrix components that may serve to concentrate C1INH at sites of inflammation. In addition, C1INH suppresses gram negative sepsis and endotoxin shock, partly via direct interaction with endotoxin that interferes with its interaction with macrophages, thereby suppressing tumour necrosis factor-a and other inflammatory mediators. C1INH treatment improves outcome in a number of disease models, including sepsis and other bacterial infections, possibly malaria, ischaemia-reperfusion injury (intestinal, hepatic, muscle, cardiac, brain), hyper-acute transplant rejection, and other inflammatory disease models. Recent data suggest that this effectiveness is the result of mechanisms that do not require protease inhibition, in addition to both complement and contact system activation.

The role of the complement and contact systems in the dextran sulfate sodium-induced colitis model: the effect of C1 inhibitor in inflammatory bowel disease.

The complement and contact systems may be involved in the pathophysiological process of inflammatory bowel disease (IBD). C1 inhibitor (C1INH) is the most important inhibitor of both the complement and contact systems. We evaluated the role of these systems and the effect of both active and inactive forms of C1INH (iC1INH) in dextran sulfate sodium (DSS)-induced colitis mouse model. Three percent DSS was used in drinking water to induce colitis in complement C3-deficient (C3(-/-)) mice, bradykinin type 2 receptor deficient (Bk(2)R(-/-)) mice, and C57BL/6 mice. After ten days DSS exposure, C3(-/-) mice exhibited markedly less weight loss than wild-type (WT) mice (12 +/- 3.3% vs. 30 +/- 1.2%, P < 0.05) and developed a milder disease-activity index (DAI), histological score, colon shortening, and myeloperoxidase (MPO) elevation (P < 0.05, respectively). The Bk(2)R(-/-) mice were not protected from the disease. Seven-day treatment with either native C1INH or iC1INH reduced the severity of the disease in WT mice, as indicated by decreased weight loss (15 +/- 1.8%, 14 +/- 2.1% vs. 30 +/- 1.2%, P < 0.05, respectively), DAI, intestinal tissue damage, and MPO elevation compared with untreated WT DSS control mice (P < 0.05, respectively). These findings suggest that complement plays a role in the development of DSS-induced colitis and that blockade of the complement system might be useful for the acute phase of IBD treatment. C1INH, however, leads to an amelioration of DSS-induced colitis via a mechanism that does not involve the inhibition of complement or contact system activation but does result in significant suppression of leukocyte infiltration.

The effect of C1 inhibitor on intestinal ischemia and reperfusion injury.

Complement activation and neutrophil stimulation are two major components in events leading to ischemia and reperfusion (IR) injury. C1 inhibitor (C1INH) inhibits activation of each of the three pathways of complement activation and of the contact system. It is also endowed with anti-inflammatory properties that are independent of protease inhibition. The goal of these studies was to investigate the role and mechanism of C1INH in alleviating IR-induced intestinal injury. C57BL/6, C1INH-deficient (C1INH(-/-)), bradykinin type 2 receptor-deficient (Bk2R(-/-)), and C3-deficient mice (C3(-/-)) were randomized into three groups: sham operated control, IR, and IR + C1INH-treated groups. Ischemia was generated by occlusion of the superior mesenteric artery followed by reperfusion. C1INH or reactive center-cleaved inactive C1INH (iC1INH) was injected intravenously before reperfusion. IR resulted in intestinal injury in C57BL/6, C1INH(-/-), Bk2R(-/-), and C3(-/-) mice with significantly increased neutrophil infiltration into intestinal tissue. In each mouse strain, C1INH treatment reduced intestinal tissue injury and attenuated leukocyte infiltration compared with the untreated IR group. C1INH inhibited leukocyte rolling in the mesenteric veins of both C57BL/6 and C3-deficient mice subjected to IR. C1INH treatment also improved the survival rate of C57BL/6 and C1INH(-/-) mice following IR. Similar findings were observed in the IR animals treated with iC1INH. These studies emphasize the therapeutic benefit of C1INH in preventing intestinal injury caused by IR. In addition to the protective activities mediated via inhibition of the complement system, these studies indicate that C1INH also plays a direct role in suppression of leukocyte transmigration into reperfused tissue.

Biological activities of C1 inhibitor.

Broadly speaking, C1 inhibitor plays important roles in the regulation of vascular permeability and in the suppression of inflammation. Vascular permeability control is exerted largely through inhibition of two of the proteases involved in the generation of bradykinin, factor XIIa and plasma kallikrein (the plasma kallikrein-kinin system). Anti-inflammatory functions, however, are exerted via several activities including inhibition of complement system proteases (C1r, C1s, MASP2) and the plasma kallikrein-kinin system proteases, in addition to interactions with a number of different proteins, cells and infectious agents. These more recently described, as yet incompletely characterized, activities serve several potential functions, including concentration of C1 inhibitor at sites of inflammation, inhibition of alternative complement pathway activation, inhibition of the biologic activities of gram negative endotoxin, enhancement of bacterial phagocytosis and killing, and suppression of the influx of leukocytes into a site of inflammation. C1 inhibitor has been shown to be therapeutically useful in a variety of animal models of inflammatory diseases, including gram negative bacterial sepsis and endotoxin shock, suppression of hyperacute transplant rejection, and treatment of a variety of ischemia-reperfusion injuries (heart, intestine, skeletal muscle, liver, brain). In humans, early data appear particularly promising in myocardial reperfusion injury. The mechanism (or mechanisms) of the effect of C1 inhibitor in these conditions is (are) not completely clear, but involve inhibition of complement and contact system activation, in addition to variable contributions from other C1 inhibitor activities that do not involve protease inhibition.

C1 inhibitor-mediated protection from sepsis.

C1 inhibitor (C1INH) protects mice from lethal Gram-negative bacterial LPS-induced endotoxin shock and blocks the binding of LPS to the murine macrophage cell line, RAW 264.7, via an interaction with lipid A. Using the cecal ligation and puncture (CLP) model for sepsis in mice, treatment with C1INH improved survival in comparison with untreated controls. The effect was not solely the result of inhibition of complement and contact system activation because reactive center-cleaved, inactive C1INH (iC1INH) also was effective. In vivo, C1INH and iC1INH both reduced the number of viable bacteria in the blood and peritoneal fluid and accelerated killing of bacteria by blood neutrophils and peritoneal macrophages. In vitro, C1INH bound to bacteria cultured from blood or peritoneal fluid of mice with CLP-induced sepsis, but had no direct effect on bacterial growth. However, both C1INH and iC1INH enhanced the bactericidal activity of blood neutrophils and peritoneal exudate leukocytes. C1INH-deficient mice (C1INH-/- mice) subjected to CLP had a higher mortality than did wild-type littermate mice. Survival of C1INH-/- mice was significantly increased with two doses of C1INH, one given immediately following CLP, and the second at 6 h post-CLP. C1INH may be important in protection from sepsis through enhancement of bacterial uptake by, and/or bactericidal capacity of, phagocytes. Treatment with C1INH may provide a useful additional therapeutic approach in some patients with peritonitis and/or sepsis.