Immunoglobulin allotypes and IgG subclass antibody response to Aspergillus fumigatus in cystic fibrosis patients

Culture independent markers of nontuberculous mycobacterial (NTM) lung infection and disease in the cystic fibrosis airway

Nontuberculous mycobacteria (NTM) are opportunistic pathogens that affect a relatively small but significant portion of the people with cystic fibrosis (CF), and may cause increased morbidity and mortality in this population. Cultures from the airway are the only test currently in clinical use for detecting NTM. Culture techniques used in clinical laboratories are insensitive and poorly suited for population screening or to follow progression of disease or treatment response. The lack of sensitive and quantitative markers of NTM in the airway impedes patient care and clinical trial design, and has limited our understanding of patterns of acquisition, latency and pathogenesis of disease. Culture-independent markers of NTM infection have the potential to overcome many of the limitations of standard NTM cultures, especially the very slow growth, inability to quantitate bacterial burden, and low sensitivity due to required decontamination procedures. A range of markers have been identified in sputum, saliva, breath, blood, urine, as well as radiographic studies. Proposed markers to detect presence of NTM or transition to NTM disease include bacterial cell wall products and DNA, as well as markers of host immune response such as immunoglobulins and the gene expression of circulating leukocytes. In all cases the sensitivity of culture-independent markers is greater than standard cultures; however, most do not discriminate between various NTM species. Thus, each marker may be best suited for a specific clinical application, or combined with other markers and traditional cultures to improve diagnosis and monitoring of treatment response.

Immunoglobulin GM and KM allotypes are associated with antibody responses to Pseudomonas aeruginosa antigens in chronically infected cystic fibrosis patients

BACKGROUND

Chronic infection with Pseudomonas aeruginosa (P. aeruginosa) is a leading cause of death in patients with cystic fibrosis (CF). Immunobiology of P. aeruginosa infection is complex and not well understood. Chronically infected CF patients generate high levels of antibodies to P. aeruginosa, but this response does not lead to clinical improvement. Therefore, additional studies aimed at identification and understanding of the host factors that influence naturally occurring immune responses to P. aeruginosa are needed. In this investigation, we evaluated the contribution of immunoglobulin GM (γ marker) and KM (κ marker) allotypes to the antibody responses to P. aeruginosa lipopolysaccharide (LPS) O1, O6, O11, and alginate antigens and the broadly-conserved surface polysaccharide expressed by many microbial pathogens, poly-N-acetyl-D-glucosamine (PNAG), in 58 chronically infected CF patients.

METHODS

IgG1 markers GM 3 and 17 and IgG2 markers GM 23- and 23+ were determined by a pre-designed TaqMan® genotyping assay. The κ chain determinants KM 1 and 3 were characterized by PCR-RFLP. Antibodies to the LPS O antigens, alginate, and PNAG were measured by an ELISA.

RESULTS

Several significant associations were noted with KM alleles. Particular KM 1/3 genotypes were individually and epistatically (with GM 3/17) associated with the level of IgG antibodies to O1, O11, alginate, and PNAG antigens.

CONCLUSIONS

Immunoglobulin GM and KM genotypes influence the magnitude of humoral immunity to LPS O, alginate, and PNAG antigens. These results, if confirmed in a larger study population, will be helpful in devising novel immunotherapeutic approaches against P. aeruginosa.

Allergic Aspects of IgG4-Related Disease: Implications for Pathogenesis and Therapy

IgG4-related disease (IgG4-RD) is a rare systemic fibroinflammatory disease frequently associated with allergy. The pathogenesis of IgG4-RD is poorly understood, and effective therapies are limited. However, IgG4-RD appears to involve some of the same pathogenic mechanisms observed in allergic disease, such as T helper 2 (Th2) and regulatory T cell (Treg) activation, IgG4 and IgE hypersecretion, and blood/tissue eosinophilia. In addition, IgG4-RD tissue fibrosis appears to involve activation of basophils and mast cells and their release of alarmins and cytokines. In this article, we review allergy-like features of IgG4-RD and highlight targeted therapies for allergy that have potential in treating patients with IgG4-RD.

MS-Based Allotype-Specific Analysis of Polyclonal IgG-Fc N-Glycosylation

Current approaches to study glycosylation of polyclonal human immunoglobulins G (IgG) usually imply protein digestion or glycan release. While these approaches allow in-depth characterization, they also result in a loss of valuable information regarding certain subclasses, allotypes and co-occuring post-translational modifications (PTMs). Unfortunately, the high variability of polyclonal IgGs makes their intact mass spectrometry (MS) analysis extremely challenging. We propose here a middle-up strategy for the analysis of the intact fragment crystallizable (Fc) region of human plasma IgGs, with the aim of acquiring integrated information of the N-glycosylation and other PTMs of subclasses and allotypes. Human plasma IgG was isolated using Fc-specific beads followed by an on-bead C _H 2 domain digestion with the enzyme IdeS. The obtained mixture of Fc subunits was analyzed by capillary electrophoresis (CE) and hydrophilic interaction liquid chromatography (HILIC) hyphenated with MS. CE-MS provided separation of different IgG-subclasses and allotypes, while HILIC-MS allowed resolution of the different glycoforms and their oxidized variants. The orthogonality of these techniques was key to reliably assign Fc allotypes. Five individual donors were analyzed using this approach. Heterozygosis was observed in all the analyzed donors resulting in a total of 12 allotypes identified. The assignments were further confirmed using recombinant monoclonal IgG allotypes as standards. While the glycosylation patterns were similar within allotypes of the same subclass, clear differences were observed between IgG subclasses and donors, highlighting the relevance of the proposed approach. In a single analysis, glycosylation levels specific for each allotype, relative abundances of subclasses and information on co-occurring modifications are obtained. This middle-up method represents an important step toward a comprehensive analysis of immunoglobulin G-Fc variants.

Serum IgE and IgG reactivity to Aspergillus recombinant antigens in patients with cystic fibrosis

PURPOSE

The diagnosis of aspergillosis in cystic fibrosis (CF) patients remains a challenge due to overlapping features of both diseases. This is further complicated by inconsistent antibody reactivity to the currently used crude antigen, which has led a more focused evaluation of the efficacy of IgE response to a number of pure Aspergillus fumigatus recombinant proteins in patients with CF and asthma. In this study, we dissected the IgE and IgG responses to multiple A. fumigatus recombinant antigens in CF patients with different Aspergillus diseases.

METHODOLOGY

Serum IgE and IgG antibodies were measured in 12 CF patients with allergic bronchopulmonary aspergillosis (ABPA), 12 with Aspergillus sensitization (AS) and 12 with Aspergillus bronchitis (AB) against recombinant antigens Asp f1, f2, f3, f4 and f6.

RESULTS

The ABPA group showed significantly greater IgE reactivity to Asp f1, f2, f3 and f4 compared to patients with AS. Patients with AB expressed higher IgG positivity to Asp f1 and Asp f2 compared with those with ABPA. There were very low IgE antibody levels against all recombinant antigens in patients with AS. Aspf1 IgG reactivity in ABPA patients correlated with positive culture.

CONCLUSION

The use of multiple recombinant antigens may improve the diagnostic accuracy in CF complicated with ABPA or AB. Asp f1 reactivity may relate to the presence of actively growing Aspergillus spp., which might be a useful marker for guiding antifungal therapy in ABPA.

Antibody response against Mycobacterium avium complex in cystic fibrosis patients measured by a novel IgG ELISA test

BACKGROUND

Early signs of Mycobacterium avium complex pulmonary disease can be missed in patients with cystic fibrosis due to subclinical infection or delays in mycobacterial culture. The aim of this study was to determine the diagnostic accuracy of a novel enzyme linked immunosorbent assay for immunoglobulin G against Mycobacterium avium complex, which could help stratify patients according to risk.

METHODS

A retrospective cross sectional analysis of serum samples from the Copenhagen Cystic Fibrosis Center was performed. Corresponding clinical data were reviewed and patients with cystic fibrosis were assigned to one of four groups based on their mycobacterial culture results. In addition, anti-Mycobacterium avium complex immunoglobulin G levels were measured longitudinally before and after first positive culture in the period 1984-2015.

RESULTS

Three-hundred and five patients with cystic fibrosis were included with a median of five nontuberculous mycobacterial cultures. Four individuals had Mycobacterium avium complex pulmonary disease at the time of cross sectional testing and their median antibody level was 22-fold higher than patients with no history of infection (1820 vs. 80 IgG units; p < 0.001). Test sensitivity was 100% (95% CI 40-100) and specificity 77% (95% CI 72-81). Longitudinal kinetics showed rising antibodies prior to first positive culture suggesting diagnostic delay.

CONCLUSIONS

Antibody screening for Mycobacterium avium complex may be used as a supplement to culture. Although confirmation in a larger cohort is needed, our findings suggest that stratifying a cystic fibrosis population into high- and low-risk groups based on antibody levels may help clinicians identify patients in need of more frequent culture.

Evaluation of a bovine antibody test for diagnosing Mycobacterium avium complex in patients with cystic fibrosis

INTRODUCTION

The aim of this study was to test a commercial bovine enzyme-linked immunosorbent assay for investigating antibody activity against Mycobacterium avium complex.

METHODS

All patients at the Copenhagen Cystic Fibrosis (CF) Center who had culture for nontuberculous mycobacteria performed were included. A commercially available antibody test used in veterinary medicine, was adjusted for human use, and applied to patient sera in a cross sectional test. The test positivity threshold was determined using a receiver operating curve (ROC). A longitudinal analysis of antibody kinetics before and after culture conversion was performed in case patients.

RESULTS

Out of 286 included subjects, six had clinical M. avium complex pulmonary disease at the time of sera sampling. These patients presented with higher antibody test values (P-value <0.01). A test cut point of 0.78 was chosen, corresponding to a sensitivity of 100% (54-100), specificity of 66% (60-72), a positive predictive value of 6% (2-13), and negative predictive value of 100% (98-100).

CONCLUSION

While not suited for direct diagnosis of M. avium complex due to a high number of false positive subjects, the assay proved useful at ruling out pulmonary disease. Screening sera from patients with CF could guide clinicians to focus attention on patients at higher risk of M. avium complex pulmonary disease. Pediatr Pulmonol. 2017;52:34-40. © 2016 Wiley Periodicals, Inc.

Ventricular tachycardia as the first manifestation of Churg-Strauss syndrome

Life-threatening arrhythmias are often found in heart diseases, but they are rare as clinical symptoms of Churg-Strauss syndrome. We report a case of a 66-year-old woman with symptomatic monomorphic ventricular tachycardia as the first sign of Churg-Strauss syndrome. Cardiac manifestations were the main clinical symptoms of the disease, and changes in other organs were weakly expressed. Furthermore, increased serum IgG4 level was revealed. It was the reason for the differential diagnosis with IgG4-related diseases. Echocardiography, cardiac magnetic resonance imaging, and histopathological analysis of biopsies had an important role in diagnosis. <Learning objective: Ventricular arrhythmias are rare clinical symptoms of Churg-Strauss syndrome. This case is interesting because cardiac manifestations were the main clinical symptom of the disease, and changes in other organs were weakly expressed. Echocardiography, cardiac magnetic resonance imaging, and histopathological analysis of biopsies had an important role in diagnosis. Increased serum IgG4 level was the reason for the differential diagnosis with IgG4-related diseases. Churg-Strauss syndrome should be considered as part of the differential diagnosis in patients with noncoronary ventricular arrhythmias.>.

Serodiagnosis of Mycobacterium abscessus complex infection in cystic fibrosis

Early signs of pulmonary disease with Mycobacterium abscessus complex (MABSC) can be missed in patients with cystic fibrosis (CF). A serological method could help stratify patients according to risk. The objective of this study was to test the diagnostic accuracy of a novel method for investigating IgG activity against MABSC.A prospective study of all patients attending the Copenhagen CF Centre was conducted by culturing for MABSC during a 22-month period and then screening patients with an anti-MABSC IgG ELISA. Culture-positive patients had stored serum examined for antibody kinetics before and after culture conversion.307 patients had 3480 respiratory samples cultured and were then tested with the anti-MABSC IgG ELISA. Patients with MABSC pulmonary disease had median anti-MABSC IgG levels six-fold higher than patients with no history of infection (434 versus 64 ELISA units; p<0.001). The test sensitivity was 95% (95% CI 74-99%) and the specificity was 73% (95% CI 67-78%). A diagnostic algorithm was constructed to stratify patients according to risk.The test accurately identified patients with pulmonary disease caused by MABSC and was suited to be used as a complement to mycobacterial culture.

Serum markers for allergic bronchopulmonary aspergillosis in cystic fibrosis: State of the art and further challenges

Allergic bronchopulmonary aspergillosis (ABPA), which results from hypersensitivity, primarily to Aspergillus, represents a severe complication in patients suffering from asthma or cystic fibrosis (CF). Since early treatment of ABPA is supposed to prevent long-term damages, ABPA has to be diagnosed promptly. However, this diagnosis is not straightforward due to clinical and radiological features of ABPA overlapping with those of CF. Despite ABPA specific diagnosis criteria proposed by the Cystic Fibrosis Foundation in 2003, making a definitive ABPA diagnosis in CF patients remains a challenge. Recent advances in the immunopathogenesis of ABPA have initiated the development of new serological tests, such as the recently reported detection of specific IgE to recombinant A. fumigatus allergens, or Thymus- and activation-regulated chemokine (TARC / CCL17), both of which are of value in the diagnosis of APBA. We review in this paper the serum markers that can advance ABPA diagnosis in CF patients, ranging from the well known criteria (anti-A. fumigatus IgE, IgG, and precipitins) to the recent biomarkers (IgE towards recombinant A. fumigatus allergens or TARC detection). Taking into account the up-dated physiopathology of ABPA, we discuss their place and their usefulness, especially TARC, to improve early ABPA detection and monitoring in CF patients.

Analysis of serum IgG subclasses in Churg-Strauss syndrome--the meaning of elevated serum levels of IgG4

OBJECTIVE

Mikulicz's disease (MD) is characterized by symmetrical and persistent enlargement of the lacrimal and salivary glands. Recently it has been categorized as an 'Ig (immunoglobulin) G4-related disease.' It presents with elevated serum levels of IgG4 and abundant infiltration of IgG4-bearing plasmacytes in involved organs. Allergic symptoms are often observed in patients with IgG4-related disease. On the other hand, allergic diseases are often complicated with Churg-Strauss syndrome (CSS). Here we focused on CSS and analyzed the relation of IgG4 in its pathogenesis.

MATERIALS AND METHODS

We analyzed five patients (2 men and 3 women) with CSS and 51 patients (20 men and 31 women) with MD who presented at Sapporo Medical University Hospital since 2001. We measured the serum concentrations of IgG subclasses in the patients with MD and CSS, and evaluated renal specimens from CSS patients, staining them for anti-IgG4 antibody.

RESULTS

We surprisingly found elevated serum levels of IgG4 not only in MD but also in CSS patients. The renal specimens in CSS patients revealed the infiltration of IgG4-positive plasmacytes.

CONCLUSION

IgG4-bearing plasmacytes may be involved in the pathogenesis of CSS, and it is possible that an allergic reaction plays an important role in the pathogenesis of IgG4-related disease.

Usefulness of serum IgG4 in the diagnosis and follow up of autoimmune pancreatitis: A systematic literature review and meta-analysis

High circulating serum immunoglobulin G4 (IgG4) levels have been proposed as a marker of autoimmune pancreatitis (AIP). The aim of the present study was to review the data existing in the English literature on the usefulness of the IgG4 serum levels in the diagnosis and follow up of patients with AIP. A total of 159 patients with AIP and 1099 controls were described in seven selected papers reporting the usefulness of serum IgG4 in diagnosing AIP. In total, 304 controls had pancreatic cancer, 96 had autoimmune diseases, and the remaining 699 had other conditions. The summary receiver-operating characteristic curve analysis was carried out by means of Meta-DiSc open-access software. Serum IgG4 showed good accuracy in distinguishing between AIP and the overall controls, pancreatic cancer and other autoimmune diseases (area under the curve [+/- SE]: 0.920 +/- 0.073, 0.914 +/- 0.191, and 0.949 +/- 0.024, respectively). The studies analyzed showed significantly heterogeneous specificity values in each of the three analyses performed. The analysis of the four studies comparing AIP and pancreatic cancers also showed significantly heterogeneous values of sensitivities and odds ratios. Regarding the usefulness of IgG4 as a marker of efficacy of steroid treatment, a decrease in the serum concentrations of IgG4 was found in the four available studies. The serum IgG4 subclass is a good marker of AIP, and its determination should be included in the diagnostic workup of this disease. However, the heterogeneity of the studies published until now means that more studies are necessary in order to better evaluate the true accuracy of IgG4 in discriminating AIP versus other autoimmune diseases.

Prevalence of allergic bronchopulmonary aspergillosis in cystic fibrosis in an area with a high frequency of atopy

BACKGROUND

Lower airway colonisation with Aspergillus fumigatus and the complicating hypersensitivity reaction allergic bronchopulmonary aspergillosis (ABPA) is well recognised in patients with cystic fibrosis (CF). There is a wide range in reported prevalence of ABPA in CF. Differences in predisposing factors such as atopy and climatic humidity, but also differences in reporting may in part explain this observation. In the Australian population there is a high frequency of atopy and the climate is relatively humid.

PATIENTS AND METHODS

Children and adolescents with CF (n = 277) from the CF Clinic, Children's Hospital at Westmead, Sydney, Australia were included in a retrospectively conducted study of Aspergillus colonisation and ABPA (1998-2003).

RESULTS

The prevalence of Aspergillus colonised patients increased significantly from 7.4% in 1998 to 18.8% in 2002. No seasonal variation in initial positive Aspergillus culture or in humidity was observed. A total of 13 patients (4.7%) were diagnosed with ABPA over the study period, with a significant increase in prevalence from 0.3% in 1998 to 4.0% in 2002. In addition, the criteria used for reporting ABPA in the study population were in agreement with the recently published diagnostic criteria for ABPA in CF.

CONCLUSIONS

In spite of a high frequency of atopy and a relatively humid climate in the Sydney area, Aspergillus colonisation and ABPA in CF patients was not disproportionate. Moreover, criteria for reporting of ABPA in this setting was not different from that in the Northern Hemisphere.