Citations

Objective To provide evidence‐based recommendations and expert guidance for the management of antineutrophil cytoplasmic antibody–associated vasculitis (AAV), including granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Methods Clinical questions regarding the treatment and management of AAV were developed in the population, intervention, comparator, and outcome (PICO) format (47 for GPA/MPA, 34 for EGPA). Systematic literature reviews were conducted for each PICO question. The Grading of Recommendations Assessment, Development and Evaluation methodology was used to assess the quality of evidence and formulate recommendations. Each recommendation required ≥70% consensus among the Voting Panel. Results We present 26 recommendations and 5 ungraded position statements for GPA/MPA, and 15 recommendations and 5 ungraded position statements for EGPA. This guideline provides recommendations for remission induction and maintenance therapy as well as adjunctive treatment strategies in GPA, MPA, and EGPA. These recommendations include the use of rituximab for remission induction and maintenance in severe GPA and MPA and the use of mepolizumab in nonsevere EGPA. All recommendations are conditional due in part to the lack of multiple randomized controlled trials and/or low‐quality evidence supporting the recommendations. Conclusion This guideline presents the first recommendations endorsed by the American College of Rheumatology and the Vasculitis Foundation for the management of AAV and provides guidance to health care professionals on how to treat these diseases.

The objective of this study was to identify signaling pathways leading to the development of interstitial fibrosis and tubular atrophy in the stenotic kidney and compensatory hypertrophy/hyperplasia of the contralateral kidney in a murine 2 kidney 1 clip model of hypertensive nephrosclerosis. Mice were studied 2, 5, and 11 weeks after undergoing surgery to establish unilateral renal artery stenosis (RAS). RAS animals, but not sham controls, became hypertensive within 1 week. Compensatory enlargement of the contralateral kidney was associated with a transient increase in proliferation (as assessed by PCNA and Mib‐1), p‐ERK, caspase 3, p27, p53, and TGF‐β expression at early time points, with return to baseline levels by 11 weeks. Tubular atrophy in the stenotic kidney was associated with a persistent increase in p‐ERK, Mib‐1, p53, p21, and p27 expression through 11 weeks. Proliferative activity was observed in tubular epithelial cells and in inflammatory cells. The atrophic kidneys had little apoptotic activity (caspase 3, TUNEL staining). The atrophic kidneys showed progressive increases in TGF‐β and α‐SMA expression and extracellular matrix deposition throughout 11 weeks. Interstitial inflammation was associated with increased MCP‐1 expression. Mechanisms underlying this differential response to unilateral RAS await definition.

Functional renal oxygen consumption, V r O 2 is due to tubular reabsorption of sodium (T Na ) in the proximal and distal nephrons, resulting in compartments (cortex/medulla) with distinct V r O 2 /T Na relationships. Compartmental divisions promote non‐invasive imaging strategies like MRI, to indirectly assess tissue oxygenation, (P t O 2 ). However, the extent to which these regional P t O 2 differences are affected by successive T Na are not fully understood. The objective is to determine V r O 2 and intra‐renal regional alterations in P t O 2 directly and indirectly during successive T Na inhibition. It is hypothesized successive T Na inhibition is accompanied by intra‐renal regional changes in P t O 2 . Pigs (n=6) underwent MRI scans at baseline, furosemide and acetazolamide. Five days later, the right kidney was instrumented with P t O 2 sensors (cortex/medulla). P t O 2 was measured during drug infusions (identical to MRI exam). There was a decrease in V r O 2 , and a 40% and 30% increase in medullary and cortical P t O 2 following drug infusions. There was ~25% medullary and ~20–30% cortical decrease in BOLD signal with furosemide and acetazolamide administration, respectively. This study suggests successive inhibition of T Na is accompanied by intra‐renal regional P t O 2 changes and these changes are detectable with BOLD‐MRI, a non‐invasive imaging modality. Funding provided by NIH Grant (HL16496‐32), 2007 APS Porter Physiology Fellowship and the Mayo Foundation.

Functional renal oxygen consumption, V r O 2 is due to tubular reabsorption of sodium (T Na ) in the proximal (∼67%) and distal(∼30%) nephrons, resulting in compartments (cortex/medulla) with distinct V r O 2 /T Na relationships. A progressive drop in renal blood flow (RBF) with renal arterial stenosis (RAS), disrupts O 2 delivery, vital for reabsorption. The overall objective for the study is to determine the intra‐renal regional alterations in tissue oxygenation (P t O 2 ) and theV r O 2 /T Na relationship in acute RAS. The hypothesis is RAS is accompanied by intra‐renal regional changes in oxygenation. Unilateral acute RAS was induced in 8 pigs by an extra‐vascular balloon. RBF and P t O 2 were measured continuously with an ultrasound flow probe during baseline, RBF autoregulation and 3 sequential decreases in RBF, recovery, and furosemide administration. V r O 2 was determined using Fick arterio‐venous differences. There were concomitant decreases in V r O 2 , and P t O 2 throughout the occlusion periods. Medullary P t O 2 changes were 35% more pronounced than cortical. This study suggests medullary decreases in P t O 2 are more aggravated than cortical changes with reductions in RBF, accentuating the medulla's vulnerability to progressive RAS. Mild to moderately severe obstructions seem to preserve the tubular transport costs. Funding provided by NIH Grant (HL16496‐32), 2007 APS Porter Physiology Fellowship and the Mayo Foundation.

The objective of this study was to define a role for chemokine generation by parenchymal cells versus circulating inflammatory cells in the initiation of renal damage in the 2K1C model of renovascular hypertension. 129 SV mice were subjected to renal artery stenosis (RAS) by placement of a polytetraethylene cuff on the right renal artery. Systolic blood pressure increased within 2 days of surgery. The cuffed kidney developed tubular atrophy, whereas the contralateral kidney developed compensatory enlargement. Immunohistochemical staining of the cuffed kidney revealed less than 2 CD3+ T cells per 200x field, and rare F4/80+ macrophages or CD20+ B cells in the first 2 weeks following RAS, with progressive increases in macrophages and T cells throughout the 6‐week observation period. Despite the relative paucity of infiltrating inflammatory cells, there was a dramatic increase in chemokine generation within the first week following RAS, as assessed by qPCR analysis of renal cortical homogenates, with 25‐fold induction of MCP‐1, 47‐fold induction of RANTES, and 15‐fold induction of MIP‐2. Chemokine generation continued to increase throughout the 6 weeks, during which circulating inflammatory cells infiltrated the cuffed kidney. Increased expression of MCP‐1 was detected in tubular epithelial cells within 1 week of RAS. We conclude that chemokine generation precedes inflammatory cell influx in RAS.

Recent studies have implicated CCR2 ‐ CCL2 signaling in macrophage influx and development of chronic renal disease in human and experimental renal artery stenosis (RAS). We sought to test the hypothesis that development of chronic renal disease would be abrogated in CCR2 knockout (KO) mice. We established RAS in CCR2 KO and WT mice (n=10) through placement of a cuff on the right renal artery We have shown that the cuff reproducibly reduces blood flow by 65% to the kidney. Sham mice underwent manipulation of the right renal artery without cuff placement. Both CCR2 KO and WT mice developed hypertension, which persisted throughout the 4 week study. There was no difference in renal atrophy between CCR2 KO (53+//‐14.6% cortical surface area) and WT (61.2%+/‐14%) mice. Furthermore, there were no significant differences in F4/80+ macrophage infiltration (12.78+/‐4.9% surface area for CCR2 KO mice and 13.13+/‐ 3.1% for WT mice) or CD3+ T cell infiltration. Infiltrating macrophages were predominantly iNOS+ M1 phenotype; few arginase+ cells were observed in any group. Urine protein excretion was similar in CCR2 KO and WT mice. CCL was induced to a similar extent in CCR2 KO and WT mice. Furthermore, no differences in CCL5, CCL7, CCR5, CCR1, or iNOS expression was observed between CCR2 KO and WT mice. We conclude that macrophage infiltration and chronic renal damage occurs in mice with deletion of CCR2. Future studies will identify signaling pathway(s) responsible for macrophage influx and chronic renal damage in this model. Grant Funding Source : AI‐100911

Renal artery stenosis (RAS) may lead to hypertension and renal injury. Reversibility of renal tubular dysfunction in RAS upon revascularization is unclear. We tested the hypothesis that percutaneous transluminal renal angioplasty (PTRA) would restore tubular function assessed as medullary oxygenation response to furosemide, a diuretic that inhibits medullary tubular transport. This was studied in 16 pigs after 6 wks of RAS, using blood oxygen level dependent magnetic resonance imaging (BOLD MRI) before and after furosemide. Renal blood flow (RBF) and glomerular filtration rate (GFR) were determined with multidetector computed tomography. Pigs were then randomized for PTRA or sham (n=8 each) and studied again 4 wks later; 8 normal pigs served as controls. Results Stenotic kidney RBF, GFR, and BOLD MRI responses were reduced in RAS shams (Figure). PTRA decreased the degree of stenosis (11±7 vs. 71±5% in untreated RAS) and blood pressure (108±3 vs. 130±9 mmHg, p<0.05). Renal and tubular function were improved in RAS+PTRA, although not to normal (Figure). Non‐stenotic kidneys showed no change in tubular function. Therefore, tubular solute transport‐related oxygen consumption can be partially restored and detected by BOLD MRI 4 wks after PTRA in post stenotic swine kidneys. This noninvasive method may be useful to assess the functional status of kidneys in RAS patients. Supported by NIH, HL085307.

We tested the hypothesis that dietary Na + intake alters the hemodynamic response to mental stress (MS) in normotensive subjects, which could be mediated by β‐adrenergic receptors (ADRB). As part of an ongoing ADRB2 phenotyping protocol, 12 subjects (age 23±5 year) completed 5 days of low (10 mmol day −1 ), normal (150) and high (400) dietary Na + intake. We measured heart rate (ECG), mean arterial pressure (MAP, Finometer), and calculated stroke volume (SV), cardiac output (CO) and systemic vascular resistance (SVR) responses to arithmetic MS, before and after administration of propranolol. The high Na + diet decreased CO (6.3±0.3 vs. 5.7±0.3 l min −1 , p<0.01) and increased SVR (1187±47 vs. 1311±68 dynes s −1 cm −1 , p<0.01) at rest, but MAP was unchanged (92±2 vs. 93±3 mmHg, p=0.37). During MS, the increase in HR, CO, and MAP was not affected by diet, nor was the decrease in SVR. However, on the high Na + diet β‐blockade increased resting MAP (93±3 vs. 97±2 mmHg, p<0.01), while the absolute MAP response to MS was unchanged, the ΔMAP was blunted (7.3 vs. 4.3 %, p=0.03) and ΔSV was decreased (1.7±3.5 vs. −5.3±2.0 %, p=0.03). In conclusion, reactivity to MS was not influenced by dietary Na + , but systemic β‐blockade after high Na + blunted the SV response during MS. This may be suggestive of augmented ADRB function or blunted non‐ADRB mechanisms of ventricular function during MS after high Na + . Support: R‐01 HL‐089331 and CTSA RR‐024150.