Renal deposits of complement factors as predictors of end-stage renal disease and death in patients with lupus nephritis.

OBJECTIVE: Lupus nephritis (LN) increases the risks of end-stage renal disease (ESRD) and death, but these risks are difficult to estimate. Since complement factors play an essential role in the pathogenesis and are deposited in the kidneys as C1q and C3, we studied whether these deposits predict ESRD and death in patients with LN. METHODS: We collected demographic, clinical and pathological data from 183 adult patients with LN classes II-V diagnosed with a first native kidney biopsy. Pathological data included the localization and intensity of immunofluorescence staining of C1q and C3. We obtained dates of incident ESRD and death from the United States Renal Data System and National Death Index, respectively, and evaluated survival curves and hazard ratios for ESRD and death as a composite outcome and as separate outcomes. RESULTS: The presence and intensity of deposits of C1q and C3 in glomeruli, tubular walls and vascular walls differed between classes and were associated with known unfavourable prognostic factors, such as hypertension, hypoalbuminemia and hypocomplementemia. However, over a median follow-up of 7.5 years, their presence and intensity were associated with neither survival free of ESRD and death nor hazard ratios for ESRD and death. CONCLUSION: Renal deposits of complement factors did not predict ESRD and death in patients with LN.

Circulating plasma metabolites and risk of rheumatoid arthritis in the Nurses' Health Study.

OBJECTIVES: RA develops slowly over years. We tested for metabolic changes prior to RA onset using a large non-targeted metabolomics platform to identify novel pathways and advance understanding of RA development. METHODS: Two hundred and fifty-four incident RA cases with plasma samples drawn pre-RA onset in the Nurses' Health Study (NHS) cohorts were matched 1:2 to 501 controls on age, race, menopause/post-menopausal hormone use and blood collection features. Relative abundances of 360 unique, known metabolites were measured. Conditional logistic regression analyses assessed associations between metabolites and incidence of RA, adjusted for age, smoking and BMI, accounting for multiple comparisons. Subgroup analyses investigated seropositive (sero+) RA and RA within 5 years of sample collection. Significant metabolites were then tested in a female military pre-RA case-control study (n = 290). RESULTS: In the NHS, metabolites associated with RA and sero+RA in multivariable models included 4-acetamidobutanoate (odds ratio (OR) = 0.80/S.d., 95% CI: 0.66, 0.95), N-acetylputrescine (OR = 0.82, 95% CI: 0.69, 0.96), C5 carnitine (OR = 0.84, 95% CI: 0.71, 0.99) and C5:1 carnitine (OR = 0.81, 95% CI: 0.68, 0.95). These were involved primarily in polyamine and leucine, isoleucine and valine metabolism. Several metabolites associated with sero+RA within 5 years of diagnosis were replicated in the independent military cohort: C5 carnitine (OR = 0.55, 95% CI: 0.33, 0.92), C5:1 carnitine (OR = 0.62, 95% CI: 0.39, 0.99) and C3 carnitine (OR = 0.57, 95% CI: 0.36, 0.91). CONCLUSION: Several metabolites were inversely associated with incidence of RA among women. Three short-chain acylcarnitines replicated in a smaller dataset and may reflect inflammation in the 5-year period prior to sero+RA diagnosis.

Comparison of an administrative algorithm for SLE disease severity to clinical SLE Disease Activity Index scores.

Systemic lupus erythematosus (SLE) severity, reflecting both disease intensity and duration, is heterogeneous making it challenging to study in administrative databases where severity may confound or mediate associations with outcomes. Garris et al. developed an administrative claims-based algorithm employing claims over a 1-year period to classify SLE severity as mild, moderate or severe. We sought to compare this administrative algorithm to a measure of SLE activity, the SLE Disease Activity Index-2000 (SLEDAI-2K) score at clinical visits. We identified 100 SLE patients followed in the Brigham and Women's Hospital (BWH) Lupus Center (in 2008-2010) with SLEDAI-2K scores at each visit over a 1-year period per person. We obtained data for the Garris algorithm for the same year per subject. We compared Garris SLE severity to the highest SLEDAI-2K in that year, with SLEDAI-2K categories of mild < 3, moderate 3-6, and severe > 6. We compared classification using weighted kappa statistics, and positive and negative predictive values (PPV, NPV). We also assessed the binary comparison of mild vs. moderate/severe. We calculated sensitivity, specificity, and McNemar's test. We analyzed 377 SLEDAI-2K assessments (mean 3.8 [SD 2.6] per subject/year). For classifying moderate/severe vs. mild SLE severity, the sensitivity was 85.7%, specificity 67.6%, PPV 81.8% and NPV 73.5%. The Garris algorithm for classifying SLE severity in administrative datasets had moderate agreement for classification of mild vs. moderate/severe SLE activity assessed by SLEDAI-2K assessments in an academic lupus center. It may be a useful tool for classifying SLE severity in administrative database studies.

Use of nuclear magnetic resonance spectroscopy in diagnosis of inborn errors of metabolism.

Nuclear Magnetic Resonance (NMR) spectroscopy has been applied in many fields of science and is increasingly being considered as a tool in the clinical setting. This review examines its application for diagnosis of inborn errors of metabolism (IEMs). IEMs, whether involving deficiency in the synthesis and degradation of metabolites, or in lipoprotein metabolism, affect nearly 3% of the global population. NMR is a preferred method for comprehensive evaluation of complex biofluids such as blood or urine, as it can provide a relatively unbiased overview of all compounds that are present and does not destroy or otherwise chemically alter the sample. While current newborn screening programs take advantage of other more sensitive methods, such as mass spectrometry, NMR has advantages especially for urine analysis with respect to ease of sample preparation and the reproducibility of results. NMR spectroscopy is particularly compatible with analysis of lipoproteins because it provides information about their size and density, not easily attained by other methods, that can help the clinician to better manage patients with dyslipidemia. We believe that NMR holds great potential for expanding clinical diagnosis in the future, in the field of IEMs and beyond.

Elevated Anti-Citrullinated Protein Antibodies Prior to Rheumatoid Arthritis Diagnosis and Risks for Chronic Obstructive Pulmonary Disease or Asthma.

OBJECTIVE: To investigate elevation of anti-citrullinated protein antibodies (ACPAs) before diagnosis of rheumatoid arthritis (RA) and risks for chronic obstructive pulmonary disease (COPD) or asthma. METHODS: We performed a matched cohort study nested within the Nurses' Health Studies among women who donated blood. Women with incident RA after blood draw (self-reported, then confirmed by medical records) were each matched to 3 controls by age, cohort, year, and menopausal factors. Pre-RA ACPA positivity was defined as >99th percentile of control distribution by a research assay or by cyclic citrullinated peptide in a subset. Incident COPD and asthma after index date (date of blood draw) were identified by questionnaires. Cox regression estimated hazard ratios (HRs) for incident COPD or asthma (in separate analyses) associated with pre-RA, pre-RA ACPA+, or pre-RA ACPA- phenotypes each compared to their matched non-RA controls. RESULTS: We analyzed 283 women who were pre-RA and 842 controls; blood was donated a mean ± SD of 9.7 ± 5.8 years before RA diagnosis. Fifty-nine women (20.8%) were pre-RA ACPA+. There were 107 cases of incident COPD and 105 incident asthma cases during 21,489 person-years of follow-up. Pre-RA ACPA+ was associated with increased COPD risk (HR 3.04 [95% confidence interval (95% CI) 1.33-7.00]) after adjusting for covariates including smoking pack-years. Pre-RA ACPA+ had an HR for asthma of 1.74 (multivariable 95% CI 0.72-4.24), similar to the risk of asthma for pre-RA ACPA- (HR 1.65 [95% CI 1.11-2.46]). CONCLUSION: Women with elevated ACPA before RA diagnosis had increased risk for developing COPD compared to controls. Women who later developed RA were more likely to develop asthma than controls, regardless of pre-RA ACPA status.

Inflammatory dietary pattern and risk of developing rheumatoid arthritis in women.

Our objective was to investigate whether a dietary pattern derived using inflammatory biomarkers is associated with rheumatoid arthritis (RA) risk. We prospectively followed 79,988 women in the Nurses' Health Study (NHS, 1984-2014) and 93,572 women in the NHSII (1991-2013); incident RA was confirmed by medical records. Food frequency questionnaires (FFQ) were completed at baseline and approximately every 4 years. Inflammatory dietary pattern was assessed from FFQ data using the Empirical Dietary Inflammatory Pattern (EDIP), including 18 anti-/pro-inflammatory food/beverage groups weighted by correlations with plasma inflammatory biomarkers (interleukin-6, C-reactive protein, and tumor necrosis factor-α receptor 2). We investigated associations between EDIP and RA using Cox regression. We identified 1185 incident RA cases over 4,425,434 person-years. EDIP was not associated with overall RA risk (p trend = 0.21 across EDIP quartiles). Among women ≤ 55 years, increasing EDIP was associated with increased overall RA risk; HRs (95% CIs) across EDIP quartiles were 1.00 (reference), 1.14 (0.86-1.51), 1.35 (1.03-1.77), and 1.38 (1.05-1.83; p for trend = 0.01). Adjusting for BMI attenuated this association. Increasing EDIP was associated with increased seropositive RA risk among women ≤ 55 years (p for trend = 0.04). There was no association between EDIP and RA among women > 55 years (EDIP-age interaction, p = 0.03). An inflammatory dietary pattern was associated with increased seropositive RA risk with onset ≤ 55 years old, and this association may be partially mediated through BMI.

Clinical characteristics and renal prognosis associated with interstitial fibrosis and tubular atrophy (IFTA) and vascular injury in lupus nephritis biopsies.

BACKGROUND: Interstitial fibrosis and tubular atrophy (IFTA) and vascular injury are frequent histologic features of lupus nephritis renal biopsies, but their clinical correlates and prognostic value are not well understood. This cohort study investigated demographic, clinical and laboratory characteristics, and outcomes, associated with IFTA and vascular injury in lupus nephritis. METHODS: Reports of all renal biopsies performed at an academic medical center (1990-2017) with WHO/ISN/RPS Class II-V lupus nephritis were reviewed. Demographics, clinical variables and labs at biopsy, treatment, and date of death were collected. Additional data from the U.S. Renal Data System (USRDS) provided dates of ESRD and death after ESRD. Multivariable regression analyses identified demographic and clinical factors associated with each histologic finding. Cumulative incidence functions and multivariable Cox proportional hazard models estimated the risk of progression to ESRD and death. RESULTS: Within 202 initial biopsies, IFTA was associated with the patient's SLICC/ACR damage index (without renal domain) and serum creatinine, and vascular injury was associated with serum creatinine in multivariable models. In Cox regression models adjusting for age, sex, race, serum creatinine, calendar year, and biopsy class, moderate/severe IFTA was associated with elevated ESRD (HRSD 5.18, 95% CI 2.53, 10.59) and death (HR 4.19, 95%CI 1.27, 13.81). After adjustment for age, sex and race, moderate/severe vascular injury was associated with ESRD (HRSD 2.13, 95% CI 1.21, 3.75) and but this relationship was not significant after adjustment for serum creatinine and calendar year. CONCLUSIONS: IFTA is a strong predictor of ESRD and death, even in proliferative nephritis, and a risk factor for poor outcomes independent of class. Vascular injury is a strong predictor of prognosis, but not independent of serum creatinine and class. The prognostic value of these lesions calls for consideration when determining treatment for lupus nephritis.

Impact and Timing of Smoking Cessation on Reducing Risk of Rheumatoid Arthritis Among Women in the Nurses' Health Studies.

OBJECTIVE: To investigate the impact and timing of smoking cessation on developing rheumatoid arthritis (RA) and serologic phenotypes. METHODS: We investigated smoking cessation and RA risk in the Nurses' Health Study (NHS) (1976-2014) and the NHS II (1989-2015). Smoking exposures and covariates were obtained by biennial questionnaires. Self-reported RA was confirmed by medical record review for American College of Rheumatology/European League Against Rheumatism criteria. Cox regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs) for RA serologic phenotypes (all, seropositive, seronegative) according to smoking status, intensity, pack-years, and years since cessation. RESULTS: Among 230,732 women, we identified 1,528 incident cases of RA (63.4% of which were seropositive) during 6,037,151 person-years of follow-up. Compared with never smoking, current smoking increased the risk of all RA (multivariable HR 1.47, 95% CI 1.27-1.72) and seropositive RA (HR 1.67, 95% CI 1.38-2.01) but not seronegative RA (HR 1.20, 95% CI 0.93-1.55). An increasing number of smoking pack-years was associated with an increased trend for the risk of all RA (P < 0.0001) and seropositive RA (P < 0.0001). With increasing duration of smoking cessation, a decreased trend for the risk of all RA was observed (P = 0.009) and seropositive RA (P = 0.002). Compared to recent quitters (<5 years), those who quit ≥30 years ago had an HR of 0.63 (95% CI 0.44-0.90) for seropositive RA. However, a modestly increased risk of RA was still detectable 30 years after quitting smoking (for all RA, HR 1.25 [95% CI 1.02-1.53]; for seropositive RA, HR 1.30 [95% CI 1.01-1.68]; reference, never smoking). CONCLUSION: These results confirm that smoking is a strong risk factor for developing seropositive RA and demonstrate for the first time that a behavior change of sustained smoking cessation could delay or even prevent seropositive RA.

Long-Term Physical Activity and Subsequent Risk for Rheumatoid Arthritis Among Women: A Prospective Cohort Study.

OBJECTIVE: To evaluate the effects of long-term physical activity on subsequent risk of rheumatoid arthritis (RA) in a prospective cohort study. METHODS: This study investigated physical activity and RA risk among women from the Nurses' Health Study II (1989-2015). Physical activity exposures and covariates were prospectively obtained using biennial questionnaires. Two rheumatologists independently reviewed the medical records of women who self-reported a new diagnosis of RA on biennial questionnaires and who screened positive for RA based on a supplemental survey. All incident RA cases met the 1987 American College of Rheumatology (ACR) or 2010 ACR/European League Against Rheumatism (EULAR) classification criteria for RA. The primary analysis investigated the long-term cumulative average number of hours spent in recreational physical activity 2-8 years prior to the RA diagnosis, a time span chosen to reduce the potential for reverse causation bias, since early RA affects physical activity prior to diagnosis. Estimated Cox regression hazard ratios (HRs) with 95% confidence intervals (95% CIs) were used to assess the risk of RA serologic phenotypes (all, seropositive, or seronegative) in relation to physical activity categories. The analyses were adjusted for body mass index (BMI) at age 18 years and time-varying potential confounders, and the mediating effect of updated BMI on the interaction between physical activity and RA risk was quantified. RESULTS: Among the 113,366 women analyzed, 506 incident RA cases (67.0% with seropositive RA) were identified during 2,428,573 person-years of follow-up. After adjustment for confounders, including smoking, dietary quality, and BMI at age 18 years, increasing cumulative average total hours of recreational physical activity was associated with a reduced risk of RA, as follows: HR 1.00 for <1 hour/week (reference), HR 1.00 (95% CI 0.78-1.29) for 1 to <2 hours/week, HR 0.92 (95% CI 0.72-1.17) for 2 to <4 hours/week, HR 0.84 (95% CI 0.63-1.12) for 4 to <7 hours/week, and HR 0.67 (95% CI 0.47-0.98) for ≥7 hours/week (P for trend = 0.02). The proportion of the effect between physical activity and RA mediated by updated BMI was 14.0% (P = 0.002) for all RA and 20.0% (P = 0.001) for seropositive RA. CONCLUSION: Higher levels of physical activity were associated with reduced RA risk. These results add to the literature implicating metabolic factors in the pathogenesis of RA.

Asthma and elevation of anti-citrullinated protein antibodies prior to the onset of rheumatoid arthritis.

BACKGROUND: Anti-citrullinated protein antibodies (ACPA) are central to rheumatoid arthritis (RA) pathogenesis and may develop at inflamed mucosa. We investigated whether asthma, a disease of airway mucosal inflammation, was associated with elevated ACPA before RA diagnosis. METHODS: We performed a nested case-control study among women in two prospective cohorts, the Nurses' Health Study (NHS; 1976-2014) and NHSII (1989-2015). Blood was obtained on a subset (NHS: 1989-1990; NHSII: 1996-1999). Cases met 1987 ACR or 2010 ACR/EULAR RA criteria by medical record review and were classified as seropositive (ACPA+ or rheumatoid factor positivity) or seronegative by clinical laboratory testing at diagnosis. We identified RA cases with blood drawn before the date of RA diagnosis (index date), matching each to three controls by age, cohort, year, time from blood draw to index date, and menopause. Pre-RA ACPA elevation for cases was defined as >99th percentile of the control distribution on a research assay composed of autoantibodies targeting citrullinated protein epitopes or positivity on the second-generation commercial assay for cyclic citrullinated peptide. Asthma status and covariates were obtained through biennial questionnaires before blood draw. Conditional logistic regression estimated ORs and 95%CIs for RA by pre-RA ACPA and clinical serostatus, adjusted for matching factors, smoking pack-years, passive smoking, and body mass index (BMI). RESULTS: We identified 284 incident RA cases and 849 matched controls; mean age at the index date was 61.2 years (SD 10.1). Blood was drawn 9.7 years (mean; SD 5.8) before the index date. We identified 96 (33.8%) RA cases with elevated pre-RA ACPA. At blood draw, 17.7% of pre-RA ACPA+ cases and 6.3% of matched controls (p = 0.0008) reported clinician-diagnosed asthma. After adjusting for matching factors, smoking pack-years, passive smoking, and BMI, asthma was significantly associated with pre-RA ACPA+ RA (OR 3.57, 95%CI 1.58,8.04). Asthma was not associated with overall RA (OR 1.45, 95%CI 0.91,2.31), but was significantly associated with seropositive RA (OR 1.79, 95%CI 1.01,3.18). CONCLUSIONS: Asthma was strongly associated with ACPA elevation in blood drawn prior to RA diagnosis, independent of smoking. Chronic mucosal airway inflammation may contribute to ACPA development and RA pathogenesis.

Cigarette smoking and the pathogenesis of systemic lupus erythematosus.

INTRODUCTION: Systemic lupus erythematosus (SLE) is a multi-system inflammatory autoimmune disease of incompletely understood etiology. It is thought that environmental exposures 'trigger' or accelerate the disease in genetically-predisposed individuals. Areas covered: Substantial epidemiological evidence exists to support the association between cigarette smoking and the risk of incident SLE. Recent evidence points to current smoking as the specific risk factor, with decreasing risk 5 years after smoking cessation, and the greatest risk for disease characterized by the presence of SLE-specific autoantibodies. Research has begun to search for possible explanations for the temporal nature of the relationship between current smoking and autoantibody positive-SLE. Here we review potential biologic mechanisms linking smoking and SLE risk, including effects upon T and B cells, inflammatory cytokines, oxidative stress, and the formation of short-lived DNA adducts. Expert commentary: The directions for future research in this field include studies of gene-environment interactions, epigenetics, metabolomics and putative biologic mechanisms.