Diana A. van Kessel

Polymorphisms in innate immunity genes associated with development of bronchiolitis obliterans after lung transplantation

BACKGROUND Activation of the immune system is suggested to prevent transplant tolerance and to promote the development of bronchiolitis obliterans syndrome (BOS). The innate immune system is activated by the interaction of pathogen-associated molecular patterns of microorganisms with Toll-like receptors (TLRs). Activation of innate immunity via TLRs was shown to be a barrier to the induction of transplantation tolerance after lung transplantation. We hypothesized that polymorphisms in 10 genes coding for TLR1 to TLR10 might contribute to an altered immune response and the subsequent development of BOS. METHODS DNA was collected from 110 lung transplant recipients. Twenty patients developed BOS. The control group comprised 422 individuals. Sixty-four single-nucleotide polymorphisms (SNPs) in 10 genes coding for TLR1 to TLR10 were genotyped. RESULTS The genotype distribution of TLR2 (rs1898830 and rs7656411), TLR4 (rs1927911) and TLR9 (rs352162 and rs187084) was significantly different between BOS(pos) patients and BOS(neg) patients and controls. The BOS(pos) group had significantly more patients with 3 or 4 of these risk alleles compared with the BOS(neg) and control groups. CONCLUSIONS Polymorphisms in TLR2, TLR4 and TLR9 that recognize bacterial and viral pathogens are associated with BOS after lung transplantation.

Systemic and exhaled cytokine and chemokine profiles are associated with the development of bronchiolitis obliterans syndrome

BACKGROUND The mechanisms that lead to the fibrotic obliteration in bronchiolitis obliterans syndrome (BOS) may involve the interactions between T-helper (Th)1 and Th2 cytokines. The aim of this study is to determine the Th1 and Th2 cytokine and chemokine profiles in serum and exhaled breath condensate (EBC) in lung transplant recipients and to assess their usefulness as biomarkers to predict the development of BOS. METHODS Serum and EBC from 10 patients with BOS (BOS(pos)) and 10 patients without BOS (BOS(neg)), matched for clinical and demographic variables, were analyzed with a multiplex immunoassay to measure a panel of 27 cytokines and chemokines. RESULTS The pro-inflammatory cytokines in serum were elevated in lung transplant recipients compared with controls. BOS(pos) patients had significantly lower concentrations of interleukin (IL)-4, IL-13, and vascular endothelial growth factor (VEGF) compared with BOS(neg) patients. The concentration of IL-5, however, was significantly higher in BOS(pos) patients. Levels of IL-4 and IL-5 were hardly detectable in EBC. IL-13 and VEGF, both decreased in serum in BOS(pos) patients, were also decreased in EBC in BOS(pos) patients compared with BOS(neg) patients. Longitudinal analysis of cytokines and chemokines in serum and EBC from the time of lung transplantation onwards did not reveal significant trends in cytokines and chemokines that preceded the diagnosis of BOS. CONCLUSIONS Levels of pro-inflammatory cytokines were increased in lung transplant recipients compared with controls. From the moment of transplantation onwards, there is a different pattern of Th2 cytokines in serum in BOS(pos) patients than in BOS(neg) patients.

Genetic polymorphisms in MMP7 and reduced serum levels associate with the development of bronchiolitis obliterans syndrome after lung transplantation

BACKGROUND Pulmonary epithelium is the primary target of injury in the development of bronchiolitis obliterans syndrome (BOS) after lung transplantation. Matrix metalloproteinases (MMP)-8 and -9 already have been implicated in the pathogenesis of BOS. MMP-7, which is involved in the repair of the lung epithelium, has not been studied in this respect. We hypothesized that genetic polymorphisms in MMP7 influence its expression and correlate with serum MMP-7 levels and the development of BOS. METHODS DNA was collected from 110 lung transplant recipients, including 21 patients with BOS. We genotyped 7 single nucleotide polymorphisms in MMP7 and measured serum MMP-7 levels. The control group comprised 422 healthy individuals. RESULTS BOS(pos) patients had lower levels of MMP-7 than BOS(neg) patients (7.87 vs 10.18 ng/ml). Significant differences in genotype and haplotype distribution between the BOS(pos) and BOS(neg) patients and controls were found. An increased risk for BOS development was found in patients homozygous for the major alleles of rs17098318, rs11568818, and rs12285347, and for the minor allele rs10502001 (odds ratio, 3.88-5.30). Haplotypes constructed with 3 or 4 risk alleles correlated with lower MMP-7 levels. CONCLUSIONS Genetic polymorphisms of MMP7 predispose to the development of BOS. Patients carrying these risk alleles express lower levels of MMP-7, which may contribute to aberrant tissue repair and culminate in the development of BOS.

Chimerism of dendritic cell subsets in peripheral blood after lung transplantation.

BACKGROUND Passenger leukocytes of donor origin are transferred to the patient resulting in circulatory microchimerism after lung transplantation (LTx). This chimeric state has been shown to occur in the total leukocyte fraction as well as unseparated peripheral blood mononuclear cells (PBMCs). In this study we determined the microchimerism levels of B cells, monocytes, natural killer (NK) and T cells and dendritic cell (DC) subsets (mDC1, mDC2 and pDC) during the first year after lung transplantation. METHODS To identify circulating donor cells, 11 donor-patient combinations were selected, which were mismatched for HLA-B8. Analysis consisted of flow cytometry on a minimum of 1 million PBMCs taken monthly up to 1 year after LTx. RESULTS Levels of microchimerism were found to be stable after LTx for all cell types investigated, although for NK+T cells an above-baseline chimerism of donor cells from the donor lung was observed in the first month after transplantation. Circulating PBMCs consisted of, on average, 0.002%, 1.7%, 0.03% and 0.001% of B cells, monocytes, NK+T cells and DCs, respectively, indicating that overall levels of microchimerism differed between the cell types investigated. In 2 patients no B-cell chimerism and in 1 patient no DC chimerism could be detected. Cell types and DC subsets of recipient origin were normally distributed. Conversely, monocytes, B cells and DCs of donor origin were increased and donor NK+T cells were decreased in number, compared with the recipient ratios. Analysis of circulating recipient DCs showed a normal distribution of mDC1s (70%), mDC2s (5%) and pDCs (25%). However, circulating donor DCs consisted of 80%, 20% and <1% of DC subsets mDC1, MDC2 and pDC, indicating that donor plasmacytoid dendritic cells were not detectable in the circulation. CONCLUSIONS In the first year after lung transplantation a stable microchimerism was detected for all cell types investigated. However, donor pDCs were consistently absent in all samples investigated, which may be linked with graft rejection often observed after LTx.

The Induction of IgM and IgG Antibodies against HLA or MICA after Lung Transplantation

The production of IgG HLA antibodies after lung transplantation (LTx) is considered to be a major risk factor for the development of chronic rejection, represented by the bronchiolitis obliterans syndrome (BOS). It has recently been observed that elevated levels of IgM HLA antibodies also correlates with the development of chronic rejection in heart and kidney transplantation. This study investigates the relationship between IgM and IgG antibodies against HLA and MICA after lung transplantation. Serum was collected from 49 patients once prior to transplantation and monthly for up to 1 year after lung transplantation was analyzed by Luminex to detect IgM and IgG antibodies against HLA and MICA. The presence of either IgM or IgG HLA and/or MICA antibodies prior to or after transplantation was not related to survival, gender, primary disease, or the development of BOS. Additionally, the production of IgG alloantibodies was not preceded by an increase in levels of IgM, and IgM levels were not followed by an increase in IgG. Under current immune suppressive regimen, although the presence of IgM antibodies does not correlate with BOS after LTx, IgM high IgG low HLA class I antibody titers were observed more in patients with BOS compared to patients without BOS.

Soluble CD30 Measured After Lung Transplantation Does Not Predict Bronchiolitis Obliterans Syndrome in a Tacrolimus/ Mycophenolate Mofetil-based Immunosuppressive Regimen

BACKGROUND The purpose of this study was to determine the utility of post-transplant serum soluble CD30 levels as a biomarker for the development of the bronchiolitis obliterans syndrome (BOS) after lung transplantation during a tacrolimus/mycophenolate mofetil-based regimen. METHODS Soluble CD30 (sCD30) concentrations were measured prior to transplantation and in 175 samples taken after transplantation in 7 patients developing BOS and 7 non-BOS patients closely matched for age, underlying diseases, follow-up and gender. RESULTS High pre-transplant sCD30 levels dropped significantly after lung transplantation, but in the post-transplant samples no differences could be detected between patients developing BOS or not, and no changes were found prior to or during the development of BOS. CONCLUSIONS After transplantation, sCD30 levels are consistently suppressed, but BOS is not prevented, indicating that sCD30 cannot be used as a biomarker to predict BOS after transplantation in the regimen employed.

Soluble CD59 is a Novel Biomarker for the Prediction of Obstructive Chronic Lung Allograft Dysfunction after Lung Transplantation

CD59 is a complement regulatory protein that inhibits membrane attack complex formation. A soluble form of CD59 (sCD59) is present in various body fluids and is associated with cellular damage after acute myocardial infarction. Lung transplantation (LTx) is the final treatment for end-stage lung diseases, however overall survival is hampered by chronic lung allograft dysfunction development, which presents itself obstructively as the bronchiolitis obliterans syndrome (BOS). We hypothesized that, due to cellular damage and activation during chronic inflammation, sCD59 serum levels can be used as biomarker preceding BOS development. We analyzed sCD59 serum concentrations in 90 LTx patients, of whom 20 developed BOS. We observed that BOS patients exhibited higher sCD59 serum concentrations at the time of diagnosis compared to clinically matched non-BOS patients (p = 0.018). Furthermore, sCD59 titers were elevated at 6 months post-LTx (p = 0.0020), when patients had no BOS-related symptoms. Survival-analysis showed that LTx patients with sCD59 titers ≥400 pg/ml 6 months post-LTx have a significant (p < 0.0001) lower chance of BOS-free survival than patients with titers ≤400 pg/ml, 32% vs. 80% respectively, which was confirmed by multivariate analysis (hazard ratio 6.2, p < 0.0001). We propose that circulating sCD59 levels constitute a novel biomarker to identify patients at risk for BOS following LTx.

Pulmonary embolism and pulmonary infarction after lung transplantation.

Venous thromboembolism (VTE), which includes pulmonary embolism (PE) and deep vein thrombosis (DVT), is a common occurrence in patients undergoing surgery and is a potentially fatal complication. Especially after lung transplantation, vascular complications can compromise the function of the allograft and limit survival. Typically, the risk of pulmonary infarction after PE in lung transplant recipients is high because the absence or poor development of the collateral bronchial circulation may predispose lung transplant recipients to pulmonary infarction. This article reports 2 cases of PE with associated pulmonary infarction after lung transplantation with significant morbidity.

Clara cell secretory protein and surfactant protein-D do not predict bronchiolitis obliterans syndrome after lung transplantation.

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Immune status assessment in adult lung transplant candidates.

BACKGROUND Lung transplant recipients have an increased susceptibility to a variety of infections due to immunosuppressive therapy. Current guidelines recommend pneumococcal and other vaccinations, prior to lung transplantation to protect against post-transplant infections, but measurement of the antibody response to vaccination is not advised. Immune status investigation in lung transplant candidates, including the response to pneumococcal polysaccharide vaccination, has not been described. METHODS Immune status investigation, including measurement of immunoglobulins, complement and the response to 23-valent pneumococcal polysaccharide vaccination (23vPPV) was performed in 81 adult lung transplant candidates. RESULTS Eighteen patients had low IgG levels and 32 patients had low IgG1 and/or IgG2 levels. After vaccination with 23vPPV the median antibody concentration of all serotypes increased significantly. Fifty-two patients had protective IgG-post-vaccination antibody levels to at least 10 serotypes. Twenty-nine patients had an impaired response to 23vPPV. CONCLUSIONS In conclusion, a significant proportion of our cohort of lung transplant candidates had one or more abnormalities in the immune status. It is likely that these patients have an increased risk for infections after transplantation. Revaccination, including measurement of antibody response, and possibly antibody replacement therapy should be considered to minimize infection risk.