The Oral and Fecal Microbiota in a Canadian Cohort of Alzheimer's Disease.

BACKGROUND: Despite decades of research, our understanding of Alzheimer's disease (AD) etiology remains incomplete. In recent years, appreciation has grown for potential roles for the microbiota in shaping neurological health. OBJECTIVE: This study aimed to examine associations between the microbiota and AD in a human cross-sectional cohort. METHODS: Forty-five AD patients and 54 matched controls were recruited in Vancouver, Canada. Fecal and oral samples underwent 16S microbiota sequencing. A wide array of demographic and clinical data were collected. Differences between participant groups were assessed, and associations between microbes and clinical variables were examined within the AD population. RESULTS: The gut microbiota of AD patients displayed lower diversity relative to controls, although taxonomic differences were sparse. In contrast, the AD oral microbiota displayed higher diversity, with several taxonomic differences relative to controls, including a lower abundance of the families Streptococcaceae and Actinomycetaceae, and a higher abundance of Weeksellaceae, among others. The periodontitis-associated oral microbe Porphyromonas gingivalis was 5 times more prevalent among patients. No significant associations between gut or oral microbes and cognition were detected, but several correlations existed between microbes and mood disorders and BMI among patients, including a strong positive correlation between Alphaproteobacteria and depression score. CONCLUSION: The gut microbiota of AD patients was not overtly different from controls, although it displayed lower diversity, an overall marker of microbiota health. The oral microbiota did display marked differences. Cognition was not associated with a microbial signature, but other relevant AD factors including mood and BMI did demonstrate an association.

Gut microbes shape microglia and cognitive function during malnutrition.

Fecal-oral contamination promotes malnutrition pathology. Lasting consequences of early life malnutrition include cognitive impairment, but the underlying pathology and influence of gut microbes remain largely unknown. Here, we utilize an established murine model combining malnutrition and iterative exposure to fecal commensals (MAL-BG). The MAL-BG model was analyzed in comparison to malnourished (MAL mice) and healthy (CON mice) controls. Malnourished mice display poor spatial memory and learning plasticity, as well as altered microglia, non-neuronal CNS cells that regulate neuroimmune responses and brain plasticity. Chronic fecal-oral exposures shaped microglial morphology and transcriptional profile, promoting phagocytic features in MAL-BG mice. Unexpectedly, these changes occurred independently from significant cytokine-induced inflammation or blood-brain barrier (BBB) disruption, key gut-brain pathways. Metabolomic profiling of the MAL-BG cortex revealed altered polyunsaturated fatty acid (PUFA) profiles and systemic lipoxidative stress. In contrast, supplementation with an ω3 PUFA/antioxidant-associated diet (PAO) mitigated cognitive deficits within the MAL-BG model. These findings provide valued insight into the malnourished gut microbiota-brain axis, highlighting PUFA metabolism as a potential therapeutic target.

The Gut Mycobiome in Parkinson's Disease.

The gut microbiome has been increasingly implicated in Parkinson's disease (PD); however, most existing studies employ bacterial-specific sequencing, and have not investigated non-bacterial microbiome constituents. Here, we use fungal-specific internal transcribed spacer (ITS)-2 amplicon sequencing in a cross-sectional PD cohort to investigate associations between the fungal gut microbiome and PD. Fungal load among participants was extremely low, and genera identified were almost exclusively of proposed dietary or environmental origin. We observed significantly lower fungal DNA relative to bacterial DNA among PD patients. No fungi differed in abundance between patients and controls, nor were any associated with motor, cognitive, or gastrointestinal features among patients.

Microbiota Composition and Metabolism Are Associated With Gut Function in Parkinson's Disease.

BACKGROUND: Parkinson's disease is characterized by a high burden of gastrointestinal comorbidities, especially constipation and reduced colonic transit time, and by gut microbiota alterations. The diverse metabolites produced by the microbiota are broadly relevant to host health. How microbiota composition and metabolism relate to gastrointestinal function in Parkinson's disease is largely unknown. The objectives of the current study were to assesses associations between microbiota composition, stool consistency, constipation, and systemic microbial metabolites in Parkinson's disease to better understand how intestinal microbes contribute to gastrointestinal disturbances commonly observed in patients. METHODS: Three hundred participants (197 Parkinson's patients and 103 controls) were recruited for this cross-sectional cohort study. Participants supplied fecal samples for microbiota sequencing (n = 300) and serum for untargeted metabolomics (n = 125). Data were collected on motor and nonmotor Parkinson's symptoms, medications, diet, and demographics. RESULTS: Significant microbiota taxonomic differences were observed in Parkinson's patients, even when controlling for gastrointestinal function. Parkinson's microbiota was characterized by reduced carbohydrate fermentation and butyrate synthesis capacity and increased proteolytic fermentation and production of deleterious amino acid metabolites, including p-cresol and phenylacetylglutamine. Taxonomic shifts and elevated proteolytic metabolites were strongly associated with stool consistency (a proxy for colonic transit time) and constipation among patients. CONCLUSIONS: Compositional and metabolic alterations in the Parkinson's microbiota are highly associated with gut function, suggesting plausible mechanistic links between altered bacterial metabolism and reduced gut health in this disease. The systemic detection of elevated deleterious proteolytic microbial metabolites in Parkinson's serum suggests a mechanism whereby microbiota dysbiosis contributes to disease etiology and pathophysiology. © 2020 International Parkinson and Movement Disorder Society.

Celebrities' Memorial Afterlives: Obituaries, Tributes, and Posthumous Gossip in the Romanian Media Deathscape.

Cross-culturally, dead are protected from posthumous negative evaluations by the universal "nil nisi bonum" precept that governs the ethics within the community of mourners. In this study, we set out to test the observance of this injunction against posthumous gossiping in the Romanian public deathscape. Obituaries and other posthumous articles (N = 1,148) were collected that covered the deaths of 63 celebrities who passed away between 2013 and 2016. Materials were gathered from the digital archives of three Romanian news sources (a news agency, a "quality" newspaper, and a tabloid), published one week after the moment of death. The findings show that 22% of the articles do contain negative evaluations of the deceased. The percentage rises to 36.4% if we restrict the sample to only those celebrities with a controversial anthumous reputation (19 of 63). These results indicate that celebrities are not spared from critical assessments after they pass away.

Rutile RuxTi1-xO2 nanobelts to enhance visible light photocatalytic activity.

We herein report on the synthesis by a facile sol-gel method without templates for preparing rutile RuxTi1-xO2 (x = 0.16; 0.07; 0.01) nanobelts with exposed (001) facets. The rutile nanobelts with exposure (001) facets, favor the separation photogenerated electron-hole pairs and inhibit the recombination of the electron-hole pairs resulting in the increase of the number of main superoxide and hydroxyl radicals. The photocatalytic properties of the rutile RuxTi1-xO2 nanobelts were evaluated by discoloring of MB (methylene blue) dye under sunlight irradiation at an intensity of 40000 lx. It was also done a thorough interface analysis to determine the band energy.

Impact of PCSK9 loss-of-function genotype on 1-year mortality and recurrent infection in sepsis survivors.

BACKGROUND: Reduced activity of proprotein convertase subtilisin/kexin type 9 (PCSK9) has been associated with decreased short-term death in patients with septic shock. Whether PCSK9 genotype influences long-term outcomes in sepsis survivors is unknown. METHODS: We evaluated the impact of PCSK9 loss-of-function (LOF) genotype on both 1-year mortality and infection-related readmission (IRR) after an index sepsis admission. The Derivation cohort included 342 patients who survived 28 days after a sepsis admission in a tertiary hospital (Vancouver/Canada, 2004-2014), while an independent Validation cohort included 1079 septic shock patients admitted at the same hospital (2000-2006). All patients were genotyped for three common missense PCSK9 LOF variants rs11591147, rs11583680, rs562556 and were classified in 3 groups: Wildtype, single PCSK9 LOF, and multiple PCSK9 LOF, according to the number of LOF alleles per patient. We also performed a meta-analysis using both cohorts to investigate the effects of PCSK9 genotype on 90-day survival. FINDINGS: In the Derivation cohort, patients carrying multiple PCSK9 LOF alleles showed lower risk for the composite outcome 1-year death or IRR (HR: 0.40, P = 0.006), accelerated reduction on neutrophil counts (P = 0.010), and decreased levels of PCSK9 (P = 0.037) compared with WT/single LOF groups. Our meta-analysis revealed that the presence of multiple LOF alleles was associated with lower 90-day mortality risk (OR = 0.69, P = 0.020). INTERPRETATION: The presence of multiple PCSK9 LOF alleles decreased the risk of 1-year death or IRR in sepsis survivors. Biological measures suggest this may be related to an enhanced resolution of the initial infection. FUNDING: Canadian Institutes of Health Research (PJT-156056).

Comparison of Linear and Non-linear Regression Analysis to Determine Pulmonary Pressure in Hyperthyroidism.

OBJECTIVES: This study aimed at assessing the incidence of pulmonary hypertension (PH) at newly diagnosed hyperthyroid patients and at finding a simple model showing the complex functional relation between pulmonary hypertension in hyperthyroidism and the factors causing it. METHODS: The 53 hyperthyroid patients (H-group) were evaluated mainly by using an echocardiographical method and compared with 35 euthyroid (E-group) and 25 healthy people (C-group). In order to identify the factors causing pulmonary hypertension the statistical method of comparing the values of arithmetical means is used. The functional relation between the two random variables (PAPs and each of the factors determining it within our research study) can be expressed by linear or non-linear function. By applying the linear regression method described by a first-degree equation the line of regression (linear model) has been determined; by applying the non-linear regression method described by a second degree equation, a parabola-type curve of regression (non-linear or polynomial model) has been determined. We made the comparison and the validation of these two models by calculating the determination coefficient (criterion 1), the comparison of residuals (criterion 2), application of AIC criterion (criterion 3) and use of F-test (criterion 4). RESULTS: From the H-group, 47% have pulmonary hypertension completely reversible when obtaining euthyroidism. The factors causing pulmonary hypertension were identified: previously known- level of free thyroxin, pulmonary vascular resistance, cardiac output; new factors identified in this study- pretreatment period, age, systolic blood pressure. According to the four criteria and to the clinical judgment, we consider that the polynomial model (graphically parabola- type) is better than the linear one. CONCLUSIONS: The better model showing the functional relation between the pulmonary hypertension in hyperthyroidism and the factors identified in this study is given by a polynomial equation of second degree where the parabola is its graphical representation.

Increased Plasma PCSK9 Levels Are Associated with Reduced Endotoxin Clearance and the Development of Acute Organ Failures during Sepsis.

PURPOSE: We have recently shown that PCSK9 reduces the clearance of endotoxin and is therefore a critical regulator of the innate immune response during infection. However, plasma PCSK9 levels during human sepsis and their relationship to outcomes are not known. Our objective was to determine the relationship between plasma PCSK9 levels and the rate of endotoxin clearance, and then correlate PCSK9 levels with the development of acute organ failures in a cohort of patients with sepsis. METHODS: Using human hepatocyte cells, we determined the threshold at which PCSK9 is able to reduce Escherichia coli endotoxin uptake by cultured human hepatocytes. In a single-centre observational cohort at St. Paul's Hospital in Vancouver, Canada, we recruited 200 patients who activated our Emergency Department's sepsis protocol and measured plasma PCSK9 and lipid levels at triage and throughout the admission. Outcomes were the development of sepsis-induced cardiovascular or respiratory failure. RESULTS: We reviewed the literature and determined that the normal human range of PCSK9 found in plasma is 170-220 ng/ml, while levels of 250 ng/ml and above reduced E. coli endotoxin clearance in cultured human hepatocytes. In septic patients, the median levels associated with new-onset respiratory and cardiovascular failure were 370 (250-500) and 380 (270-530) ng/ml, respectively, versus 270 (220-380) ng/ml in patients who did not go on to develop any organ failure (p = 0.003 and 0.005, respectively). CONCLUSIONS: Plasma PCSK9 levels are greatly increased in sepsis. At normal levels, PCSK9 has no influence upon hepatocyte bacterial endotoxin clearance, but as levels rise, there is a progressive inhibition of clearance. During sepsis, PCSK9 levels are highly correlated with the development of subsequent multiple organ failure. Inhibition of PCSK9 activity is an attractive target for treating the spectrum of sepsis and septic shock.

Phytotherapeutic activity of Euphorbia cyparissias extracts on Ixodidae (Acari) female ticks.

BACKGROUND: Given its numerous biologically active components, Euphorbiaceae has been found to be a large plant family and polyvalent with quite interesting therapeutic activity that can be studied. MATERIALS AND METHODS: The ixodicidal activity of Euphorbia cyparissias extracts was studied in vitro and in vivo. Tested concentrations were 10, 5, 2, 1, 0.5 and 0.25%. RESULTS: For the in vitro study, conducted on field-collected female specimens of Dermacentor marginatus and Haemaphysalis punctata, the efficacy results showed that the ticks died after exposure in the case of 10, 5, and 2% tincture concentrations. The effects appeared after 30 minutes and became more visible 120 minutes after each exposure. The statistical differences regarding the used concentrations were found to be: F = 6.51, df = 5, P < 0.001. The in vivo study of the efficacy of E. cyparissias concentrations was performed on 35 naturally infested sheep and on 30 bovines parasitized with Ixodes ricinus, sprayed with tincture and glycerinate dilutions (bovines) on days 0 and 7. The results revealed detrimental effects on the survivability of female ticks, the most prominent being the reduction of their movement capacity. In sheep in vivo efficiency observed within 24 hrs varied, between 1 and 23% for D. marginatus and between 7 and 27% for H. punctata and respectively between 2 and 53% after 24 hrs, for I. ricinus, comparable effects being also found 72 hrs after the second administration of Euphorbia extracts. CONCLUSION: Extracts from E. cyparissias may be used, with results, as an ecologic alternative tick control management method, being a cheap solution, with a sizeable role in reducing the use of synthetic and/or other harming and resistance source ixodicidal conditionings.

PCSK9 is a critical regulator of the innate immune response and septic shock outcome.

A decrease in the activity of proprotein convertase subtilisin/kexin type 9 (PCSK9) increases the amount of low-density lipoprotein (LDL) receptors on liver cells and, therefore, LDL clearance. The clearance of lipids from pathogens is related to endogenous lipid clearance; thus, PCSK9 may also regulate removal of pathogen lipids such as lipopolysaccharide (LPS). Compared to controls, Pcsk9 knockout mice displayed decreases in inflammatory cytokine production and in other physiological responses to LPS. In human liver cells, PCSK9 inhibited LPS uptake, a necessary step in systemic clearance and detoxification. Pharmacological inhibition of PCSK9 improved survival and inflammation in murine polymicrobial peritonitis. Human PCSK9 loss-of-function genetic variants were associated with improved survival in septic shock patients and a decrease in inflammatory cytokine response both in septic shock patients and in healthy volunteers after LPS administration. The PCSK9 effect was abrogated in LDL receptor (LDLR) knockout mice and in humans who are homozygous for an LDLR variant that is resistant to PCSK9. Together, our results show that reduced PCSK9 function is associated with increased pathogen lipid clearance via the LDLR, a decreased inflammatory response, and improved septic shock outcome.

Advanced glycation end products, aortic stiffness, and wave reflection in peritoneal dialysis as compared to hemodialysis.

BACKGROUND: Modification of vascular extracellular matrix by advanced glycation end products (AGEs) may result in vascular stiffness. Because of higher exposure to glucose, we hypothesized that patients on peritoneal dialysis (PD) may have higher tissue levels of AGEs, increased vascular stiffness, and enhanced central augmentation pressure as compared to hemodialysis patients (HD). METHODS: In a cross-sectional study, 43 PD were matched to 43 HD based on age, gender, diabetes, and dialysis vintage. Tissue levels of AGEs were assessed by skin autofluorescence (skin AF). Aortic stiffness was measured by carotid-femoral pulse wave velocity (cf-PWV), and heart rate-adjusted augmentation pressure (AP@75) was performed by arterial tonometry. RESULTS: Baseline characteristics were similar in both groups except for lower prevalence of cardiovascular disease (CVD) and higher exposure to smoking in PD. Skin AF and cf-PWV were not statistically different, but PD patients had a lower AP@75 (P = 0.023). However, after adjustments for prevalence of CVD and smoking status, skin AF was higher in PD by 0.587 AU (95 % CI 0.091-1.215, P = 0.020), and cf-PWV was higher in PD by 2.20 m/s (95 % CI 0.56-3.84, P = 0.009), while AP@75 was not different. Overall, there was a significant association between skin AF and cf-PWV and AP@75. CONCLUSION: Skin AF and aortic stiffness were higher in PD after adjustments for imbalances in baseline characteristics. Independent of dialysis modality, there was a positive association between skin AF, aortic stiffness, and enhanced wave reflection.

Determinants of progression of aortic stiffness in hemodialysis patients: a prospective longitudinal study.

Aortic stiffness is associated with increased cardiovascular mortality in patients with chronic kidney disease. However, the rate of progression of arterial stiffness and the role of cardiovascular risk factors in the progression of arterial stiffness has never been established in a longitudinal study. In a prospective, longitudinal, observational study, carotid-femoral pulse wave velocity and carotid-radial pulse wave velocity were assessed in 109 hemodialysis patients at baseline and after a mean follow-up of 1.2 years. We examined the impact of age, atherosclerotic cardiovascular disease, diabetes mellitus, dialysis vintage, and pentosidine (a well-characterized, advanced glycation end products) on the rate of progression of aortic stiffness. The annual rate of changes in carotid-femoral pulse wave velocity and carotid-radial pulse wave velocity were 0.84 m/s per year (95% confidence interval, 0.50-1.12 m/s per year) and -0.66 m/s per year (95% confidence interval, -0.85 to -0.47 m/s per year), respectively. Older subjects, and patients with diabetes mellitus or atherosclerotic cardiovascular disease had higher aortic stiffness at baseline, however, the rate of progression of aortic stiffness was only determined by plasma pentosidine levels (P=0.001). The degree of baseline aortic stiffness was a significant determinant of the regression of brachial stiffness (P<0.001) suggesting that the regression of brachial stiffness occurs in response to central aortic stiffness. These findings suggest that traditional cardiovascular risk factors may play some role in the progression of aortic stiffness before development of advanced chronic kidney disease, and that the enhanced rate of progression of aortic stiffness in chronic kidney disease patients on dialysis are probably determined by more specific chronic kidney disease-related risk factors such as advanced-glycation end products.

Lithium diisopropylamide-mediated ortholithiation of 2-fluoropyridines: rates, mechanisms, and the role of autocatalysis.

Lithium diisopropylamide (LDA)-mediated ortholithiations of 2-fluoropyridine and 2,6-difluoropyridine in tetrahydrofuran at -78 °C were studied using a combination of IR and NMR spectroscopic and computational methods. Rate studies show that a substrate-assisted deaggregation of LDA dimer occurs parallel to an unprecedented tetramer-based pathway. Standard and competitive isotope effects confirm post-rate-limiting proton transfer. Autocatalysis stems from ArLi-catalyzed deaggregation of LDA proceeding via 2:2 LDA-ArLi mixed tetramers. A hypersensitivity of the ortholithiation rates to traces of LiCl derives from LiCl-catalyzed LDA dimer-monomer exchange and a subsequent monomer-based ortholithiation. Fleeting 2:2 LDA-LiCl mixed tetramers are suggested to be key intermediates. The mechanisms of both the uncatalyzed and catalyzed deaggregations are discussed. A general mechanistic paradigm is delineated to explain a number of seemingly disparate LDA-mediated reactions, all of which occur in tetrahydrofuran at -78 °C.

BDNF and its pro-peptide are stored in presynaptic dense core vesicles in brain neurons.

Although brain-derived neurotrophic factor (BDNF) regulates numerous and complex biological processes including memory retention, its extremely low levels in the mature central nervous system have greatly complicated attempts to reliably localize it. Using rigorous specificity controls, we found that antibodies reacting either with BDNF or its pro-peptide both stained large dense core vesicles in excitatory presynaptic terminals of the adult mouse hippocampus. Both moieties were ~10-fold more abundant than pro-BDNF. The lack of postsynaptic localization was confirmed in Bassoon mutants, a seizure-prone mouse line exhibiting markedly elevated levels of BDNF. These findings challenge previous conclusions based on work with cultured neurons, which suggested activity-dependent dendritic synthesis and release of BDNF. They instead provide an ultrastructural basis for an anterograde mode of action of BDNF, contrasting with the long-established retrograde model derived from experiments with nerve growth factor in the peripheral nervous system.

Age-related and blood pressure-independent reduction in aortic stiffness after kidney transplantation.

OBJECTIVES: Aortic stiffness is a novel cardiovascular risk factor in patients with chronic kidney disease (CKD). The purpose of the present study is to examine whether there is a blood pressure-independent improvement in aortic stiffness 3 months after successful kidney transplantation (KTx), and whether this improvement is age-dependent. METHOD: In this prospective, longitudinal observational study, we studied hemodynamic and biological parameters prior to and 3 months after a KTx in 52 stage 5 CKD patients. Aortic stiffness was measured by carotido-femoral pulse wave velocity (c-f PWV) and enhanced central wave reflection was evaluated by the heart rate-adjusted central augmentation index (AIx) by means of arterial tonometry. Endothelin-1, L-arginine, asymmetric dimethylarginine (biomarkers of endothelial dysfunction), pentosidine (advanced glycation end-products) and mineral metabolism parameters were also measured. RESULTS: After adjusting for the reduction in mean blood pressure, c-f PWV decreased significantly from 12.1 ± 3.3 to 11.6 ± 2.3 m/s (P < 0.05). In an analysis stratified by age, this improvement was only present in patients older than 50 years of age as compared with patients younger than 50 years of age (-5.5 ± 2.2 vs. 2.1 ± 1.9%, P < 0.05). AIx decreased from 22 ± 11 to 14 ± 13% (P < 0.01), but this reduction was not age-dependent. We also observed a similar degree of improvement in the biomarker levels of endothelial dysfunction and pentosidine in both groups. CONCLUSION: This study shows for the first time that there is an age-dependent improvement in aortic stiffness after KTx. These observations suggest that older patients may have an added cardiovascular risk reduction after a successful KTx.

Mechanism of lithium diisopropylamide-mediated substitution of 2,6-difluoropyridine.

Treatment of 2,6-difluoropyridine with lithium diisopropylamide in THF solution at -78 degrees C effects ortholithiation quantitatively. Warming the solution to 0 degrees C converts the aryllithium to 2-fluoro-6-(diisopropylamino)pyridine. Rate studies reveal evidence of a reversal of the ortholithiation and a subsequent 1,2-addition via two monomer-based pathways of stoichiometries [ArH*i-Pr(2)NLi(THF)](double dagger) and [ArH*i-Pr(2)NLi(THF)(3)](double dagger). Computational studies fill in the structural details and provide evidence of a direct substitution without the intermediacy of a Meisenheimer complex.

The impact of arteriovenous fistulas on aortic stiffness in patients with chronic kidney disease.

BACKGROUND: The creation of arteriovenous fistulas (AVF) in patients with advanced chronic kidney disease (CKD) has been shown to have adverse effects on their central pulse wave profile suggesting a likely increase in arterial stiffness. The aim of the present study was to directly evaluate the effect of AVF on arterial stiffness. Method. Thirty-one stage-5 CKD patients underwent haemodynamic assessment prior to and 3 months after creation of AVF. Haemodynamic assessment included measurement of blood pressure (BP), central and carotidal pulse wave profile analysis, and carotido-femoral and carotido-radial pulse wave velocities (PWV). Pre-AVF and post-AVF haemodynamic parameters were compared using the Wilcoxon signed-rank test or the paired Student t-test as appropriate. Pearson correlations, single and multiple linear regressions, were used to determine the association between variables. RESULTS: After creation of AVF, peripheral and central BPs decreased without significant change in heart rate (HR) or pulse pressure. Carotido-femoral PWV ((c-f)PWV) fell from 13.2 +/- 4.1 to 11.7 +/- 3.1 m/s (P < 0.001). There was an increase in the central augmentation index (20.8% +/- 11.5 versus 23.7% +/- 11.6, P = 0.07) of borderline significance, and a significant reduction in the subendocardial viability ratio (153% +/- 34 versus 143% +/- 32, P < 0.05), which was mainly the result of a decrease in the diastolic pressure time index (DPTI) without any significant change in the diastolic duration. The reduction of (c-f)PWV was explained by changes in mean BP and HR (R(2) = 0.29). The reduction in DPTI was related to changes in central diastolic BP and changes in end-systolic BP (adjusted R(2) = 0.87). The significant improvement in aortic stiffness was mostly the result of the relative reduction of (c-f)PWV in the subgroup of patients with baseline (c-f)PWV above the median value of 13 m/s. CONCLUSION: The creation of AVF is associated with a passive improvement of aortic stiffness especially in patients with stiffer arteries. This improvement in arterial stiffness could potentially be beneficial to the cardiovascular system despite an associated deterioration in the aortic pulse wave profile.

Binding of avian IgY to type VII collagen does not activate complement and leucocytes and fails to induce subepidermal blistering in mice.

BACKGROUND: Epidermolysis bullosa acquisita (EBA) is a severe autoimmune skin disease characterized by tissue-bound and circulating autoantibodies to type VII collagen, the major component of anchoring fibrils. When passively transferred into mice, rabbit IgG against type VII collagen induces Fc-dependent activation of complement, the recruitment of leucocytes into the skin, and subepidermal blistering. In addition to these inflammatory mechanisms, clinical and experimental evidence suggests that antibodies against type VII collagen might induce blisters by disrupting the ligand function of type VII collagen by an Fc-independent mechanism. OBJECTIVES: To study noninflammatory mechanisms of blister formation in experimental EBA. METHODS: We generated chicken IgY antibodies directed to recombinant type VII collagen and examined their pathogenic activity using ex vivo and animal models. RESULTS: Mice injected with these chicken IgY antibodies showed binding of the antibodies to the dermal-epidermal junction of skin sections. However, IgY antibodies did not fix complement C3 in enzyme-linked immunosorbent assay and immunofluorescence complement-binding assays. In addition, IgY antibodies did not induce dermal-epidermal separation ex vivo. Following their passive transfer into Balb/c mice, chicken IgY antibodies against type VII collagen bound at the dermal-epidermal junction, but, in contrast to rabbit IgG, did not fix complement C3, recruit granulocytes, or induce skin blisters. CONCLUSIONS: These findings demonstrate that binding of avian IgY to type VII collagen is not pathogenic in vivo and strongly suggest that in experimental EBA, antibodies to type VII collagen induce blisters not by direct disruption of the ligand function of type VII collagen, but rather by an Fc-dependent engagement of humoral and cellular inflammatory factors.