Hypoxia Increases the Potential for Neutrophil-mediated Endothelial Damage in Chronic Obstructive Pulmonary Disease

Rationale: Patients with chronic obstructive pulmonary disease (COPD) experience excess cardiovascular morbidity and mortality, and exacerbations further increase the risk of such events. COPD is associated with persistent blood and airway neutrophilia and systemic and tissue hypoxia. Hypoxia augments neutrophil elastase release, enhancing capacity for tissue injury. Objective: To determine whether hypoxia-driven neutrophil protein secretion contributes to endothelial damage in COPD. Methods: The healthy human neutrophil secretome generated under normoxic or hypoxic conditions was characterized by quantitative mass spectrometry, and the capacity for neutrophil-mediated endothelial damage was assessed. Histotoxic protein concentrations were measured in normoxic versus hypoxic neutrophil supernatants and plasma from patients experiencing COPD exacerbation and healthy control subjects. Measurements and Main Results: Hypoxia promoted PI3Kγ-dependent neutrophil elastase secretion, with greater release seen in neutrophils from patients with COPD. Supernatants from neutrophils incubated under hypoxia caused pulmonary endothelial cell damage, and identical supernatants from COPD neutrophils increased neutrophil adherence to endothelial cells. Proteomics revealed differential neutrophil protein secretion under hypoxia and normoxia, and hypoxia augmented secretion of a subset of histotoxic granule and cytosolic proteins, with significantly greater release seen in COPD neutrophils. The plasma of patients with COPD had higher content of hypoxia-upregulated neutrophil-derived proteins and protease activity, and vascular injury markers. Conclusions: Hypoxia drives a destructive "hypersecretory" neutrophil phenotype conferring enhanced capacity for endothelial injury, with a corresponding signature of neutrophil degranulation and vascular injury identified in plasma of patients with COPD. Thus, hypoxic enhancement of neutrophil degranulation may contribute to increased cardiovascular risk in COPD. These insights may identify new therapeutic opportunities for endothelial damage in COPD.

The Biological Effects of Double-Dose Alpha-1 Antitrypsin Augmentation Therapy. A Pilot Clinical Trial

Rationale: Augmentation therapy with intravenous AAT (alpha-1 antitrypsin) is the only specific therapy for individuals with pulmonary disease from AAT deficiency (AATD). The recommended standard dose (SD; 60 mg/kg/wk) elevates AAT trough serum levels to around 50% of normal; however, outside of slowing emphysema progression, its effects in other clinical outcomes have not been rigorously proven.

Objectives: To evaluate the biological effects of normalizing AAT trough levels with double-dose (DD) therapy (120 mg/kg/wk) in subjects with AATD already receiving SD therapy.

Methods: Clinically stable subjects were evaluated after 4 weeks of SD therapy, followed by 4 weeks of DD therapy, and 4 weeks after return to SD therapy. At the end of each phase, BAL fluid (BALF) and plasma samples were obtained.

Measurements and Main Results: DD therapy increased trough AAT levels to normal and, compared with SD therapy, reduced serine protease activity in BALF (elastase and cathepsin G), plasma elastase footprint (Aα-Val³⁶⁰), and markers of elastin degradation (desmosine/isodesmosine) in BALF. DD therapy also further downregulated BALF ILs and cytokines including Jak-STAT (Janus kinases–signal transducer and activator of transcription proteins), TNFα (tumor necrosis factor-α), and T-cell receptor signaling pathways, cytokines involved in macrophage migration, eosinophil recruitment, humoral and adaptive immunity, neutrophil activation, and cachexia. On restarting SD after DD treatment, a possible carryover effect was seen for several biological markers.

Conclusions: Subjects with AATD on SD augmentation therapy still exhibit inflammation, protease activity, and elastin degradation that can be further improved by normalizing AAT levels. Higher AAT dosing than currently recommended may lead to enhanced clinical benefits and should be explored further.

Clinical trial registered with www.clinicaltrials.gov (NCT 01669421).

A specific proteinase 3 activity footprint in α1-antitrypsin deficiency

α₁-Antitrypsin (α₁-AT) deficiency is a risk factor for emphysema due to tissue damage by serine proteases. Neutrophil elastase (NE) has long been considered the enzyme responsible. However, proteinase 3 (PR3) also produces the pathological features of chronic obstructive pulmonary disease (COPD), is present in the same granules in the neutrophil and is inhibited after NE. We developed a specific footprint assay for PR3 activity and assessed its relationship to an NE footprint in α₁-AT deficiency.

An ELISA was developed for the specific PR3 fibrinogen cleavage site Aα-Val⁵⁴¹. Levels were measured in plasma from 239 PiZZ patients, 94 PiSZ patients, 53 nondeficient healthy smokers and 78 individuals with usual COPD. Subjects underwent extensive demographic characterisation including full lung function and lung computed tomography scanning.

Aα-Val⁵⁴¹ was greater than the NE footprint in all cohorts, consistent with differential activity. Values were highest in the PiZZ α₁-AT-deficient patients and correlated with the NE marker Aα-Val³⁶⁰, but were ∼17 times higher than for the NE footprint, consistent with a greater potential contribution to lung damage. Aα-Val⁵⁴¹ was related cross-sectionally to the severity of lung disease (forced expiratory volume in 1 s % pred: r_s= −0.284; p<0.001) and was sensitive to augmentation therapy, falling from 287.2 to 48.6 nM (p<0.001).

An in vivo plasma footprint of PR3 activity is present in greater quantities than an NE footprint in patients with α₁-AT deficiency, is sensitive to augmentation therapy and represents a likely biomarker for dose-ranging studies.

This novel assay provides evidence of proteinase 3 activity in α₁-antitrypsin deficiency, suggesting it may play a significant role in lung tissue damage and act as a specific biomarker for augmentation therapyhttp://bit.ly/32dnx66

Impact of month of birth on the development of autoimmune thyroid disease in the United Kingdom and Europe

CONTEXT

Viral/bacterial infection is proposed as a trigger for the autoimmune thyroid diseases (AITD): Graves' disease (GD) and Hashimoto's thyroiditis (HT). Previous studies in European Caucasian AITD subjects found higher birth rates in the autumn/winter, suggesting those born in the autumn/winter experience increased viral/bacterial exposure after birth, impacting upon immune system development and predisposing to AITD later in life.

OBJECTIVE

Month of birth effects were investigated in three independent European Caucasian AITD datasets.

DESIGN

Variation in GD and HT onset was compared across months and seasons, with fluctuations across all 12 months analyzed using a Walter-Elwood test.

SETTING

The study was conducted at a research laboratory.

PATIENTS

National UK Caucasian AITD Case Control Collection (2746 GD and 502 HT compared with 1 423 716 UK births), National UK Caucasian GD Family Collection (239 GD and 227 unaffected siblings), and OXAGEN AITD Caucasian Family Collection (885 GD, 717 HT, and 794 unaffected siblings of European Caucasian decent).

MAIN OUTCOME MEASURES

Case-control and family-based association studies were measured.

RESULTS

No consistent month of birth effects were detected in GD females or males across all three collections. In HT females from the OXAGEN AITD Caucasian Family Collection, slightly higher birth rates were detected in autumn (Walter's test statistic = 7.47, P = .024) however, this was not seen in the HT females from the case-control cohort.

CONCLUSION

Our results suggest in UK/Northern European Caucasian GD subjects, month of birth does not impact on AITD development. Although some month of birth effects for HT females in one collection cannot be excluded, only further work in larger European Caucasian AITD collections can confirm these effects.

Skewed X chromosome inactivation and female preponderance in autoimmune thyroid disease: an association study and meta-analysis

CONTEXT

A number of small data sets have suggested a potential role for skewed X chromosome activation (XCI), away from the expected 50:50 parent of origin ratio, as an explanation for the strong female preponderance seen in the common autoimmune thyroid diseases (AITD), Graves' disease (GD), and Hashimoto's thyroiditis (HT).

OBJECTIVE

The objective of the study was to confirm a role for XCI skewing as a potential explanation for the strong female preponderance seen in AITD.

DESIGN

The design of the study was to screen XCI in the largest GD, HT, and control case-control cohort and family cohort to date and undertake a meta-analysis of previous AITD XCI reports.

SETTING

The study was conducted at a research laboratory.

PATIENTS

Three hundred and nine GD, 490 HT, and 325 female UK Caucasians controls, 273 UK Caucasian GD families, and a meta-analysis of 454 GD, 673 HT, and 643 female Caucasian controls were included in the study.

MAIN OUTCOME MEASURES

Case-control and family-based association studies and meta-analysis were measured.

RESULTS

Skewed XCI was observed with GD [odds ratio (OR) 2.17 [95% confidence interval (CI) 1.43-3.30], P=2.1×10(-4)] and a trend toward skewing with HT (P=.08) compared with the control cohort. A meta-analysis of our UK data and that of four previous non-UK Caucasian studies confirmed significant skewing of XCI with GD [OR 2.54 (95% CI 1.58-4.10), P=1.0×10(-4), I2=30.2%] and HT [OR 2.40 (95% CI 1.10-5.26), P=.03, I2=74.3%].

CONCLUSIONS

Convincing evidence exists to support a role for skewed XCI in female subjects with AITD, which may, in part, explain the strong female preponderance observed in this disease.

Association of Fc receptor-like 5 (FCRL5) with Graves' disease is secondary to the effect of FCRL3

OBJECTIVE

The Fc receptor-like 3 (FCRL3) molecule, involved in controlling B-cell signalling, may contribute to the autoimmune disease process. Recently, a genome-wide screen detected association of neighbouring gene FCRL5 with Graves' disease (GD). To determine whether FCRL5 represents a further independent B-cell signalling GD susceptibility loci, we screened 12 tag SNPs, capturing all known common variation within FCRL5, in 5192 UK Caucasian GD index cases and controls.

DESIGN

A case-control association study investigating twelve tag SNPs within FCRL5 which captured the majority of known common variation within this gene region.

PATIENTS

A data set comprising 2504 UK Caucasian patients with GD and 2688 geographically matched controls taken from the 1958 British Birth cohort.

MEASUREMENTS

We used the chi-squared test and haplotype analysis to investigate the association between the tag SNPs and GD before performing logistic regression analysis to determine whether association at FCRL5 was independent of the known FCRL3 association.

RESULTS

Three of the FCRL5 tag SNPs, rs6667109, rs3811035 and rs6692977 showed association with GD (P = 0·015-0·001, OR = 1·15-1·16). Logistic regression performed on all FCRL5 and, previously screened, FCRL3 tag SNPs revealed that association with FCRL5 was secondary to linkage disequilibrium with the FCRL3, rs11264798 and rs10489678 SNPs.

CONCLUSIONS

FCRL5 does not appear to be exerting an independent effect on the development of GD in the UK. Fine mapping of the entire FCRL region is required to determine the exact location of the aetiological variant/s present.

Association of FcGRIIa with Graves' disease: a potential role for dysregulated autoantibody clearance in disease onset/progression

OBJECTIVE

Although autoantibody production is a key feature of autoimmunity, it is not known whether variation in autoantibody production and clearance pathways is involved in disease susceptibility. The Fc Gamma Receptor IIa (FcGRIIa) molecule is involved in the clearance of autoantibodies and a functional single nucleotide polymorphism (SNP), rs1801274, which has been shown to alter autoantibody clearance, has been associated with a number of autoimmune diseases (AIDs) including systemic lupus erythematosus and type 1 diabetes. This study aimed to determine whether FcGRIIa is associated with Graves' disease (GD) in the UK Caucasian population by Tag SNP screening common polymorphisms within the FcGRIIa region.

DESIGN

A case control association study investigating nine Tag SNPs within FcGRIIa, which captured the majority of known common variation within this gene region.

PATIENTS

A dataset comprising 2504 UK Caucasian GD patients and 2784 geographically matched controls taken from the 1958 British Birth cohort.

MEASUREMENTS

We used the chi(2)-test to investigate association between the Tag SNPs and GD.

RESULTS

Association between the rs1801274 (P = 0.003, OR = 1.12 [95% CI = 1.03-1.22] and rs6427598 (P = 0.012, OR = 0.90 [95% CI = 0.83-0.98]) SNPs and GD was observed. No other SNPs showed association with GD. No associations were seen between any of the SNPs investigated and specific GD clinical phenotypes.

CONCLUSIONS

This study suggests that variation in FcGRIIa predisposes to GD and further supports the role of FcGRIIa as a susceptibility locus for AIDs in general.

Follow-up of potential novel Graves' disease susceptibility loci, identified in the UK WTCCC genome-wide nonsynonymous SNP study

A recent association scan using a genome-wide set of nonsynonymous coding single-nucleotide polymorphisms (nsSNPs) conducted in four diseases including Graves' disease (GD), identified nine novel possible regions of association with GD. We used a case-control approach in an attempt to replicate association of these nine regions in an independent collection of 1578 British GD patients and 1946 matched Caucasian controls. Although none of these loci showed evidence of association with GD in the independent data set, when combined with the original Wellcome Trust Case-Control Consortium study group, minor differences in allele frequencies (P>or=10(-3)) remained in the combined collection of 5924 subjects for four of the nsSNPs, present within HDLBP, TEKT1, JSRP1 and UTX. An additional 29 Tag SNPs were screened within these four gene regions to determine if further associations could be detected. Similarly, minor differences only (P=0.042-0.002) were detected in two HDLBP and two TEKT1 Tag SNPs in the combined UK GD collection. In conclusion, it is unlikely that the SNPs selected in this replication study have a significant effect on the risk of GD in the United Kingdom. Our study confirms the need for large data sets and stringent analysis criteria when searching for susceptibility loci in common diseases.

Confirmation of association of chromosome 5q31-33 with United Kingdom Caucasian Graves' disease

BACKGROUND

Previous genome-wide microsatellite screening in Graves' disease (GD) has suggested several regions of linkage to disease. Although replication has been inconsistent, some regions such as chromosome 5q31-33 have been associated with several Oriental GD patient cohorts. Recently, two studies have reported association of single-nucleotide polymorphism (SNP) rs31480 in interleukin 3 (IL-3) and the rs1368408 and SNP75 (-623 approximately -622 AG/-T) SNPs in secretoglobulin family 3a member 2 (SCGB3A2) with GD and suggested that this may account for linkage to the 5q31-33 region in Oriental GD datasets. We sought to confirm this association in a large Caucasian U.K. GD cohort.

METHODS

The rs31480 SNP was shown to tag all known common variations in IL-3 and the rs1368408 SNP was shown to tag all common variations in SCGB3A2. The SCGB3A2 SNP75 was found to be rare in the U.K. Caucasian population and, therefore, was not screened. We genotyped rs31480 and rs1368408 and performed a case-control association study in 2504 GD cases and 2688 controls from the U.K.

RESULTS

Association between the SCGB3A2 rs1368408 SNP and GD was detected (p = 0.007, odds ratio = 1.18, 95% confidence intervals = 1.05-1.33). No association between the IL-3 rs31804 SNP and U.K. Caucasian GD patients was observed.

CONCLUSIONS

These data suggest that chromosome 5q31-q33 contains a susceptibility locus for Caucasian GD patients as well as Oriental GD patients. Although association was detected between SCGB3A2 and U.K. Caucasian GD subjects, the size of effect was smaller than that seen in the Oriental population (odds ratio = 1.28-1.73). Fine mapping within this region will be required to determine the exact location of the etiological variants present within this region for both Caucasian and Oriental GD patients.

Association of the thyroid stimulating hormone receptor gene (TSHR) with Graves' disease

Graves' disease (GD) is a common autoimmune disease (AID) that shares many of its susceptibility loci with other AIDs. The thyroid stimulating hormone receptor (TSHR) represents the primary autoantigen in GD, in which autoantibodies bind to the receptor and mimic its ligand, thyroid stimulating hormone, causing the characteristic clinical phenotype. Although early studies investigating the TSHR and GD proved inconclusive, more recently we provided convincing evidence for association of the TSHR region with disease. In the current study, we investigated a combined panel of 98 SNPs, including 70 tag SNPs, across an extended 800 kb region of the TSHR to refine association in a cohort of 768 GD subjects and 768 matched controls. In total, 28 SNPs revealed association with GD (P < 0.05), with strongest SNP associations at rs179247 (chi(2) = 32.45, P = 8.90 x 10(-8), OR = 1.53, 95% CI = 1.32-1.78) and rs12101255 (chi(2) = 30.91, P = 1.95 x 10(-7), OR = 1.55, 95% CI = 1.33-1.81), both located in intron 1 of the TSHR. Association of the most associated SNP, rs179247, was replicated in 303 GD families (P = 7.8 x 10(-4)). In addition, we provide preliminary evidence that the disease-associated genotypes of rs179247 (AA) and rs12101255 (TT) show reduced mRNA expression ratios of flTSHR relative to two alternate TSHR mRNA splice variants.

The TNFalpha gene relates to clinical phenotype in alpha-1-antitrypsin deficiency

BACKGROUND

Genetic variation may underlie phenotypic variation in chronic obstructive pulmonary disease (COPD) in subjects with and without alpha 1 antitrypsin deficiency (AATD). Genotype specific sub-phenotypes are likely and may underlie the poor replication of previous genetic studies. This study investigated subjects with AATD to determine the relationship between specific phenotypes and TNFalpha polymorphisms.

METHODS

424 unrelated subjects of the PiZZ genotype were assessed for history of chronic bronchitis, impairment of lung function and radiological presence of emphysema and bronchiectasis. A subset of subjects with 3 years consecutive lung function data was assessed for decline of lung function. Four single nucleotide polymorphisms (SNPs) tagging TNFalpha were genotyped using TaqMan(R) genotyping technologies and compared between subjects affected by each phenotype and those unaffected. Plasma TNFalpha levels were measured in all PiZZ subjects.

RESULTS

All SNPs were in Hardy-Weinberg equilibrium. A significant difference in rs361525 genotype (p = 0.01) and allele (p = 0.01) frequency was seen between subjects with and without chronic bronchitis, independent of the presence of other phenotypes. TNFalpha plasma level showed no phenotypic or genotypic associations.

CONCLUSION

Variation in TNFalpha is associated with chronic bronchitis in AATD.

Tag SNP screening of the PDCD1 gene for association with Graves' disease

OBJECTIVE

The Programmed Cell Death 1 gene (PDCD1) on chromosome 2q37.3 encodes PD-1 which is involved in providing a negative signal to activated T cells. Large case-control studies have shown association of PDCD1 with several autoimmune diseases although, to date, no such studies have been performed for Graves' disease (GD). The objective of our study was to investigate eight tag SNPs representing the majority of common variation in PDCD1 within a well-characterized large UK Caucasian GD dataset.

DESIGN

A case control association study of eight polymorphisms.

PATIENTS

2671 Graves' disease patients and 864 controls.

MEASUREMENTS

Tests for association with disease.

RESULTS

No association with disease was seen for any of the +4163, +5049, +5318, +5640, +5678 and +7078 SNPs genotyped in this study. Association was detected between the +2375 SNP (P = 0.021, OR = 1.14 [95% CI = 1.01-1.29]) and GD and a small protective effect was seen with the +6799 SNP genotypes (P = 0.028, OR = 0.77 [95% CI = 0.58-1.03]).

CONCLUSIONS

This study has, for the first time, shown that small effects within PDCD1 may contribute towards the development of GD, supporting the hypothesis that much of the currently unknown genetic contribution to GD could be due to several small genetic effects with ORs 1.2. Replication of this result is now needed to confirm our findings and justify more detailed fine mapping of a primary aetiological variant in this gene region.

Use of Tag single nucleotide polymorphisms (SNPs) to screen PTPN21: no association with Graves' disease

OBJECTIVE

The protein-tyrosine-phosphate nonreceptor 22 gene (PTPN22) has recently been identified as a susceptibility locus for a number of autoimmune diseases including Graves' disease (GD). PTPN21 is another member of the PTPN family and its gene PTPN21 maps to the first reported region of genetic linkage to GD, GD-1, on chromosome 14q31. The aim of this study was to determine whether PTPN21 is acting as a GD susceptibility locus in UK Caucasian subjects.

DESIGN

A case control association study of seven Tag single nucleotide polymorphisms (SNPs) (rs1469602, rs8007288, rs1998670, rs11622270, rs2274736, rs2295136 and rs366476) selected to predict 51 un-genotyped polymorphisms present within PTPN21.

PATIENTS

Unrelated Caucasian patients of UK origin with GD and ethnically and gender matched control subjects with no family history of autoimmune disease were recruited. In total, DNA was obtained from 768 GD patients and 768 control subjects.

RESULTS

No association of any of the seven Tag SNPs was detected with GD. Preliminary evidence of association of rs2274736 was found with younger age of GD onset (0-30 years) (OR = 1. 48 [95% CI = 1.11-1.97]). No other correlations with clinical phenotype or previously established susceptibility loci were detected.

CONCLUSIONS

Using a Tag SNP approach we screened PTPN21 as a susceptibility locus for GD and found no evidence for association with disease. Preliminary evidence for association of rs2274736 with younger age of GD onset requires replication in similar sized data sets to exclude a false positive result. Methods such as the Tag SNP approach significantly reduce the amount of genotyping required when screening candidate loci, including those within regions of chromosomal linkage.