Mast Cell Activation in the Systemic Sclerosis Esophagus

Introduction

Previously, we discovered similar esophageal gene expression patterns in patients with systemic sclerosis (SSc) and eosinophilic esophagitis (EoE) where eosinophil/mast cell-targeted therapies are beneficial. Because SSc and EoE patients experience similar esophageal symptoms, we hypothesized that eosinophil/mast cell-directed therapy may potentially benefit SSc patients. Herein, we determine the association between esophageal mast cell quantities, gene expression and clinical parameters in order to identify SSc patients who may benefit from eosinophil/mast cell-directed therapy.

Methods

Esophageal biopsies from SSc patients and healthy participants were stained for tryptase, a mast cell marker, and associations with relevant clinical parameters including 24h esophageal pH testing were assessed. Intra-epithelial mast cell density was quantified by semi-automated microscopy. Microarray data were utilized for functional and gene set enrichment analyses and to identify intrinsic subset (IS) assignment, an SSc molecular classification system that includes inflammatory, proliferative, limited and normal-like subsets.

Results

Esophageal biopsies from 40 SSc patients (39 receiving proton pump inhibition) and eleven healthy participants were studied. Mast cell numbers in both the upper esophagus (r_s = 0.638, p = 0.004) and the entire (upper + lower) esophagus (r_s = 0.562, p = 0.019) significantly correlated with acid exposure time percentage. The inflammatory, fibroproliferative, and normal-like ISs originally defined in skin biopsies were identified in esophageal biopsies. Although esophageal mast cell numbers in SSc patients and healthy participants were similar, gene expression for mast cell-related pathways showed significant upregulation in the inflammatory IS of SSc patients compared to patients classified as proliferative or normal-like.

Discussion

Esophageal mast cell numbers are heterogeneous in SSc patients and may correlate with acid exposure. Patients with inflammatory IS profiles in the esophagus demonstrate more tryptase staining. Mast cell targeted therapy may be a useful therapeutic approach in SSc patients belonging to the inflammatory IS, but additional studies are warranted.

Mycophenolate Mofetil Treatment of Systemic Sclerosis Reduces Myeloid Cell Numbers and Attenuates the Inflammatory Gene Signature in Skin

Fewer than half of patients with systemic sclerosis demonstrate modified Rodnan skin score improvement during mycophenolate mofetil (MMF) treatment. To understand the molecular basis for this observation, we extended our prior studies and characterized molecular and cellular changes in skin biopsies from subjects with systemic sclerosis treated with MMF. Eleven subjects completed ≥24 months of MMF therapy. Two distinct skin gene expression trajectories were observed across six of these subjects. Three of the six subjects showed attenuation of the inflammatory signature by 24 months, paralleling reductions in CCL2 mRNA expression in skin and reduced numbers of macrophages and myeloid dendritic cells in skin biopsies. MMF cessation at 24 months resulted in an increased inflammatory score, increased CCL2 mRNA and protein levels, modified Rodnan skin score rebound, and increased numbers of skin myeloid cells in these subjects. In contrast, three other subjects remained on MMF >24 months and showed a persistent decrease in inflammatory score, decreasing or stable modified Rodnan skin score, CCL2 mRNA reductions, sera CCL2 protein levels trending downward, reduction in monocyte migration, and no increase in skin myeloid cell numbers. These data summarize molecular changes during MMF therapy that suggest reduction of innate immune cell numbers, possibly by attenuating expression of chemokines, including CCL2.

Cryptococcosis in liver and kidney transplant recipients receiving anti-thymocyte globulin or alemtuzumab

Rabbit anti-thymocyte globulin (ATG) and alemtuzumab have been used for induction or preconditioning and for the treatment of acute rejection in organ transplant recipients in many centers. Such regimens may lead to a substantial decline in the CD4 lymphocyte count to levels seen in other population groups at high risk of cryptococcosis. In view of this, we examined the impact of such therapy on the cumulative incidence of cryptococcosis among liver and kidney recipients. A total of 834 liver and 727 kidney transplants were performed during the study period. Seven hundred and eighty-one patients did not receive ATG or alemtuzumab; 646 received 1 dose of either drug, and 134 patients received 2 doses of either drug. The cumulative incidence of cryptococcosis was 0.26% (2/781) among those who did not receive ATG or alemtuzumab; 0.3% (2/646) among those who received only 1 dose, and 2.24% (3/134) among those who received 2 doses (P=0.03). There were 5 cases of cryptococcosis in liver recipients and 2 in kidney recipients. There were 3 cases of cryptococcal meningitis, 3 of pneumonia, and 1 of disseminated disease. The 2 kidney recipients had meningitis. Diagnosis occurred at a median of 255 days (range 7-517) after transplantation. The mortality rate was 14.2%. We conclude that the use of 1 dose of ATG or alemtuzumab is not associated with an increased cumulative incidence of cryptococcosis, but that those patients receiving 2 doses are at increased risk.

Survival of liver transplant patients coinfected with HIV and HCV is adversely impacted by recurrent hepatitis C

Although liver transplantation (LTx) in HIV-positive patients receiving highly active antiretroviral therapy (HAART) has been successful, some have reported poorer outcomes in patients coinfected with hepatitis C virus (HCV). Here we discuss the impact of recurrent HCV on 27 HIV-positive patients who underwent LTx. HIV infection was well controlled post-transplantation. Survival in HIV-positive/HCV-positive patients was shorter compared to a cohort of HIV-negative/HCV-positive patients matched in age, model for end-stage liver disease (MELD) score, and time of transplant, with cumulative 1-, 3- and 5-year patient survival of 66.7%, 55.6% and 33.3% versus 75.7%, 71.6% and 71.6%, respectively, although not significantly (p = 0.07), and there was a higher likelihood of developing cirrhosis or dying from an HCV-related complication in coinfected subjects (RR = 2.6, 95% CI, 1.06-6.35; p = 0.03). Risk factors for poor survival included African-American race (p = 0.02), MELD score > 20 (p = 0.05), HAART intolerance postLTx (p = 0.01), and postLTx HCV RNA > 30000000 IU/mL (p = 0.00). Recurrent HCV in 18 patients was associated with eight deaths, including three from fibrosing cholestatic hepatitis. Among surviving coinfected recipients, five are alive at least 3 years after LTx, and of 15 patients treated with interferon-alpha/ribavirin, six (40%) are HCV RNA negative, including four with sustained virological response. Hepatitis C is a major cause of graft loss and patient mortality in coinfected patients undergoing LTx.

Vocal intensity in falsetto phonation of a countertenor: an analysis by synthesis approach

An analysis by synthesis paradigm was implemented to model glottal airflow and vocal tract acoustics for the falsetto phonation of a trained countertenor. Changes in vocal intensity were measured as a function of subglottal pressure, open quotient of the time-varying glottal airflow pulse, and formant tuning. The contributions of laryngeal adduction (open quotient of the glottal flow pulse) and of formant tuning to intensity change were derived from modeled data. The findings were: (1) Subglottal pressure accounted for almost 90% of the variation in SPL in falsetto phonation. (2) The open quotient of the glottal flow pulse was remarkably constant in these falsetto phonations, and thus did not affect vocal intensity significantly. (3) Formant tuning occurred in two out of nine possibilities for the vowel /a/. These instances did not support the concept of systematic exploitation of formant tuning.

Three-dimensional vocal tract imaging and formant structure: varying vocal register, pitch, and loudness

Although advances in techniques for image acquisition and analysis have facilitated the direct measurement of three-dimensional vocal tract air space shapes associated with specific speech phonemes, little information is available with regard to changes in three-dimensional (3-D) vocal tract shape as a function of vocal register, pitch, and loudness. In this study, 3-D images of the vocal tract during falsetto and chest register phonations at various pitch and loudness conditions were obtained using electron beam computed tomography (EBCT). Detailed measurements and differences in vocal tract configuration and formant characteristics derived from the eight measured vocal tract shapes are reported.

Mechanisms permitting nephrotic patients to achieve nitrogen equilibrium with a protein-restricted diet

Clinical experience suggests nephrotic patients are at risk for malnutrition. To determine if nephrotic patients can adapt successfully to a protein-restricted diet, nephrotic (glomerular filtration rate, 52+/-15 ml/min; urinary protein [Uprot.], 7.2+/-2.2 grams/d) and control subjects completed a crossover comparison of diets providing 0.8 or 1.6 grams protein (plus 1 gram protein/gram Uprot.) and 35 kcal per kg per day. Nitrogen balance (BN) was determined and whole body protein turnover measured during fasting and feeding using intravenous -[1-13C]leucine and intragastric -[5,5, 5- 2H3]leucine. BN was positive in both nephrotic and control subjects consuming either diet and rates of whole-body protein synthesis, protein degradation, and leucine oxidation did not differ between groups. In both nephrotic and control subjects anabolism was due to a suppression of whole-body protein degradation and stimulation of protein synthesis during feeding. The principal compensatory response to dietary protein restriction was a decrease in amino acid oxidation and this response was the same in both groups. With the low protein diet leucine oxidation rates during feeding correlated inversely with Uprot. losses (r = -0.83; P < 0. 05).

CONCLUSIONS

(a) a diet providing 0.8 gram protein (plus 1 gram protein/gram Uprot.) and 35 kcal per kg per day maintains BN in nephrotic patients; (b) nephrotic patients activate normal anabolic responses to dietary protein restriction (suppression of amino acid oxidation) and feeding (stimulation of protein synthesis and inhibition of protein degradation); (c) the inverse correlation between leucine oxidation and Uprot. losses suggests that proteinuria is a stimulus to conserve dietary essential amino acids.

How is lean body mass conserved with the very-low protein diet regimen?

Eight CRF patients (GFR = 18.8 +/- 2.7 ml/min) underwent a crossover comparison of a very-low-protein diet (VLPD) providing 0.28 g protein and 35 kcal/kg/day, plus an isomolar mixture of ketoacids (KA) or essential amino acids (EAA). During each dietary period, a 5-day nitrogen balance (BN) was performed and whole-body protein turnover (WBPT) was measured during fasting and feeding using intravenous [1-13C]leucine and intragastric [5,5,5-2H3]leucine. Although the VLPD/KA regimen contained 15% less nitrogen, BN was neutral and did not differ between the regimens. Similarly, rates of WBPT did not differ between the KA or EAA regimens, and neutral BN was achieved by a marked suppression of amino acid oxidation and postprandial inhibition of protein degradation (PD). Participants were then discharged on the VLPD/KA regimen and monitored as outpatients for > or = 1 year. Repeat BN was neutral and rates of WBPT did not differ from baseline values. Thus, the adaptive responses to dietary protein restriction are sustained during long-term therapy.

Long-term adaptive responses to dietary protein restriction in chronic renal failure

Six patients with chronic renal failure (glomerular filtration rate 18 +/- 2 ml/min) underwent two 10-day admissions separated by at least 1 yr of outpatient therapy with a very low-protein diet (VLPD) providing 0.28 g protein.kg-1.day-1 plus an amino acid-ketoacid supplement. During each Clinical Research Center admission, subjects completed a 5-day nitrogen balance (BN), and whole body protein turnover was measured during fasting and feeding using intravenous [1-13C]leucine and intragastric [5,5,5-2H3]leucine. Outpatient dietary protein compliance was very good (25 vs. 20 g protein/day or 125% goal), whereas energy intake was only 69% of goal (24 vs. 35 kcal.kg-1.day-1). During the 16 +/- 2 mo of dietary therapy, there were no changes in serum proteins or anthropometrics. BN after > or = 1 yr of dietary therapy was neutral and did not differ from initial values (+0.46 +/- 0.20 vs. +0.55 +/- 0.19 g N/day). Similarly, rates of whole body protein synthesis, degradation, and leucine oxidation after long-term therapy with the VLPD regimen did not differ from baseline values, and neutral BN was maintained by a marked suppression of amino acid oxidation and postprandial inhibition of protein degradation. This is the first evidence that the compensatory changes in whole body protein turnover activated in response to dietary protein restriction are sustained during long-term therapy.

Vancomycin redistribution: dosing recommendations following high-flux hemodialysis

Although increased vancomycin clearance has been reported with highly permeable hemodialysis membranes (such as polysulfone), failure to consider post-dialysis redistribution could lead to unnecessary dosage supplementation. In protocol 1, twelve hemodialysis patients admitted for vascular access thrombectomy received 15 mg/kg of vancomycin as surgical prophylaxis. Post-operatively, patients underwent high-flux hemodialysis (HFHD) for two hours using a Fresenius F-80 polysulfone dialyzer (QB = 417 +/- 49, QD = 800 ml/min). Vancomycin's intradialytic clearance increased 13-fold compared to the patient's endogenous clearance (120 +/- 59 vs. 9 +/- 8 ml/min, respectively) yet dialysate recovery indicated that only 17% of body stores were removed (179 +/- 70 mg). Although serum vancomycin levels decreased 33% during HFHD, vancomycin levels increased in all patients following dialysis and the post-rebound values reached 87% of the pre-dialysis concentration. In protocol 2, eight outpatients receiving maintenance HFHD with a F-80 dialyzer (Kt/V = 1.29 +/- 0.08) were given 20 mg/kg of vancomycin immediately following dialysis on Monday; pre- and post-levels were measured during the next three dialysis treatments. The predialysis serum vancomycin levels were > 7.5 micrograms/ml (9.7 +/- 1.0 micrograms/ml; range 8.0 to 11.0) in all patients the following Monday. Thus, vancomycin clearance is increased during HFHD, but redistribution post-HD minimizes changes in serum levels. We recommend a 20 mg/kg i.v. loading dose and subsequent doses of 15 mg/kg every seven days; to account for individual variability, weekly vancomycin levels should be drawn before dialysis.

Effects of nutritional copper deficiency on the biomechanical properties of bone and arterial elastin metabolism in the chick

Increased bone fragility was observed in chickens fed diets containing less than 1 ppm copper. Using a device that was designed to measure torsion during fracture, it could be demonstrated that bone from copper-deficient chicks fractured with less deformation and torque than bone from control chicks. The collagen of bone from copper-deficient chicks appeared to contain fewer cross-links than normal bone. The introduction of artificial cross-links into collagen from copper-deficient chick bone by formaldehyde and NaBH4 treatments improved bone strength and strain (deformation) so that it was comparable with normal bone. Copper deficiency blocks the formation of cross-links in collagens and elastin from various tissues. It is felt that the bone fragility related to nutritional copper deficiency is the result of decreased bone collagen cross linking. Arterial elastin metabolism was also investigated. By radioactively labeling arterial soluble elastin (tropoelastin) in vivo by an intraperitoneal injection of [G-3H]valine, it could be demonstrated that copper deficiency appeared to reduce its rate of metabolic turnover. Soluble elastin or tropoelastin is assumed to be the precursor of mature or insoluble elastin. The observations presented here are consistent with the view that by retarding the steps associated with elastin cross-link formation, the incorporation of soluble elastin into mature elastin may be retarded as well.