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

Influence of highly effective modulator therapy on the sputum proteome in cystic fibrosis

BACKGROUND

There have been dramatic clinical improvements in people with cystic fibrosis (PwCF) commenced on the cystic fibrosis conductance regulator (CFTR) modulator elexacaftor/tezacaftor/ivacaftor (ETI). Sputum proteomics is a powerful research technique capable of identifying important airway disease mechanisms. Using this technique, we evaluated how ETI changes the sputum proteome in PwCF.

METHODS

Sputum samples from 21 CF subjects pre- and post- ETI, 6 CF controls ineligible for ETI, and 15 healthy controls were analysed by liquid chromatography mass spectrometry.

RESULTS

Post-ETI, mean FEV1 % increased by 13.7 % (SD 7.9). Principal component and hierarchical clustering analysis revealed that the post-ETI proteome shifted to an intermediate state that was distinct from pre-ETI and healthy controls, even for those achieving normal lung function. Functional analysis showed incomplete resolution of neutrophilic inflammation. The CF control sputum proteome did not alter. At the protein-level many more proteins increased in abundance than decreased following ETI therapy (80 vs 30; adjusted p value <0.05), including many that have anti-inflammatory properties. Of those proteins that reduced in abundance many were pro-inflammatory neutrophil-derived proteins. Several important respiratory proteases were unchanged.

CONCLUSIONS

Sputum proteomics can provide insights into CF lung disease mechanisms and how they are modified by therapeutic intervention, in this case ETI. This study identifies imbalances in pro- and anti- inflammatory proteins in sputum that partially resolve with ETI even in those achieving normal spirometry values. This post-ETI intermediate state could contribute to ongoing airway damage and therefore its relevance to clinical outcomes needs to be established.

Voluntary wheel running prevents formation of membrane attack complexes and myelin degradation after peripheral nerve injury

Regular aerobic activity is associated with a reduced risk of chronic pain in humans and rodents. Our previous studies in rodents have shown that prior voluntary wheel running can normalize redox signaling at the site of peripheral nerve injury, attenuating subsequent neuropathic pain. However, the full extent of neuroprotection offered by voluntary wheel running after peripheral nerve injury is unknown. Here, we show that six weeks of voluntary wheel running prior to chronic constriction injury (CCI) reduced the terminal complement membrane attack complex (MAC) at the sciatic nerve injury site. This was associated with increased expression of the MAC inhibitor CD59. The levels of upstream complement components (C3) and their inhibitors (CD55, CR1 and CFH) were altered by CCI, but not increased by voluntary wheel running. Since MAC can degrade myelin, which in turn contributes to neuropathic pain, we evaluated myelin integrity at the sciatic nerve injury site. We found that the loss of myelinated fibers and decreased myelin protein which occurs in sedentary rats following CCI was not observed in rats with prior running. Substitution of prior voluntary wheel running with exogenous CD59 also attenuated mechanical allodynia and reduced MAC deposition at the nerve injury site, pointing to CD59 as a critical effector of the neuroprotective and antinociceptive actions of prior voluntary wheel running. This study links attenuation of neuropathic pain by prior voluntary wheel running with inhibition of MAC and preservation of myelin integrity at the sciatic nerve injury site.

Predictive value of soluble CD59 for poor 28-day neurological prognosis and all-cause mortality in patients after cardiopulmonary resuscitation: a prospective observatory study

BACKGROUND

sCD59, as a soluble form of CD59, is observed in multiple types of body fluids and correlated with the cell damage after ischemia/reperfusion injury. This study aims to observe the dynamic changes of serum sCD59 in patients after restoration of spontaneous circulation (ROSC) and explore the association of serum sCD59 with neurological prognosis and all-cause mortality in patients after ROSC.

METHODS

A total of 68 patients after ROSC were prospectively recruited and divided into survivors (n = 23) and non-survivors (n = 45) groups on the basis of 28-day survival. Twenty healthy volunteers were enrolled as controls. Serum sCD59 and other serum complement components, including sC5b-9, C5a, C3a, C3b, C1q, MBL, Bb, and pro-inflammatory mediators tumor necrosis factor (TNF)-α, interleukin-6 (IL-6), neurological damage biomarkers neuron-specific enolase (NSE) and soluble protein 100β (S100β) were measured by enzyme linked immunosorbent assay on day 1, 3, and 7 after ROSC. Neurologic outcome was assessed using cerebral performance category scores, with poor neurologic outcome defined as 3-5 points.

RESULTS

In the first week after ROSC, serum levels of sCD59, sC5b-9, C5a, C3a, C3b, C1q, MBL, Bb, TNF-α, IL-6, NSE and S100β were significantly elevated in patients after ROSC compared to healthy volunteers, with a significant elevation in the non-survivors compared to survivors except serum C1q and MBL. Serum sCD59 levels were positively correlated with serum sC5b-9, TNF-α, IL-6, NSE, S100β, SOFA score and APACHE II score. Moreover, serum sCD59 on day 1, 3, and 7 after ROSC could be used for predicting poor 28-day neurological prognosis and all-cause mortality. Serum sCD59 on day 3 had highest AUCs for predicting poor 28-day neurological prognosis [0.862 (95% CI 0.678-0.960)] and 28-day all-cause mortality [0.891 (95% CI 0.769-0.962)]. In multivariate logistic regression analysis, the serum level of sCD59_D1 was independently associated with poor 28-day neurological prognosis and all-cause mortality.

CONCLUSIONS

The elevated serum level of sCD59 was positively correlated with disease severity after ROSC. Moreover, serum sCD59 could have good predictive values for the poor 28-day neurological prognosis and all-cause mortality in patients after ROSC.

The bioinformatics analysis of CD59 in Helicobacter pylori infected gastric cancer

BACKGROUND

Cell surface molecules play important roles in cell signal transduction pathways during microbial infection.

OBJECTIVE

In this study, the expression and the functions of CD59 was investigated in H. pylori infected gastric cancer (GC).

METHODS AND RESULTS

The differential expression of CD59 and the influence of H. pylori on the expression of CD59 were analyzed via bioinformatics through Gene Set Enrichment in GC. In addition, the expression of CD59 in GES-1, AGS cells and GC tissues infected with H. pylori was confirmed by Western blot. Bioinformatics results and H. pylori infection experiments showed CD59 decreased obviously in H. pylori infected GC cells and tissues. The expression of CD59 was linked to the survival rate of GC patients, and influenced various immune cells in the immune microenvironment of GC. CD59 interacts with other genes to form a network in H. pylori infected GC. Certainly, CD59 decreased significantly in H. pylori infected GC tissues, GES-1 and AGS cells in vitro.

CONCLUSION

H. pylori infection could influence the expression of CD59 in GC indicating that CD59 may be a promising treatment target.

Complement regulatory proteins: Candidate biomarkers in differentiating tuberculosis pleural effusion

Background and aims

Complement activation is essential for tuberculosis pleural effusion. However, little is known about the value of complement regulatory protein (CD46, CD55, and CD59) in the differential diagnosis of tuberculosis.

Materials and methods

Ninety-nine patients with exudative pleural effusion admitted to Xiangya Hospital of Central South University from June 1, 2021to November 14, 2022 were enrolled. The expression levels of soluble CD46 (sCD46), soluble CD55 (sCD55), and soluble CD59 (sCD59) in pleural effusion were quantified by enzyme-linked immunosorbent assay, and the receiver operating characteristic (ROC) curves were plotted to evaluate the diagnostic and co-diagnostic values.

Results

The ADA level is higher in TPE patients than non-TPE patients. It is well-found that TPE patients had lower levels of sCD46, sCD55, and sCD59 compared with non-TPE patients. Moreover, the expression of sCD46, sCD55, and sCD59 in pleural effusion was negatively correlated with ADA. In addition, the diagnostic efficacy of sCD46, sCD55 and sCD59 was comparable to that of ADA, with 0.896, 0.857, 0.858 and 0.893, respectively. Furthermore, combine detection of sCD46, sCD55, sCD59 and ADA could improve the diagnostic accuracy.

Conclusions

Complement regulatory factors (CD46, CD55, and CD59) were validated by this project to be promising candidate biomarkers for the diagnosis of TPE with high accuracy. The combination of the CD46, CD55, and CD59 and ADA assay exist a better diagnostic value in TPE.

Markers of Bronchiolitis Obliterans Syndrome after Lung Transplant: Between Old Knowledge and Future Perspective

Bronchiolitis obliterans syndrome (BOS) is the most common form of CLAD and is characterized by airflow limitation and an obstructive spirometric pattern without high-resolution computed tomography (HRCT) evidence of parenchymal opacities. Computed tomography and microCT analysis show abundant small airway obstruction, starting from the fifth generation of airway branching and affecting up to 40-70% of airways. The pathogenesis of BOS remains unclear. It is a multifactorial syndrome that leads to pathological tissue changes and clinical manifestations. Because BOS is associated with the worst long-term survival in LTx patients, many studies are focused on the early identification of BOS. Markers may be useful for diagnosis and for understanding the molecular and immunological mechanisms involved in the onset of BOS. Diagnostic and predictive markers of BOS have also been investigated in various biological materials, such as blood, BAL, lung tissue and extracellular vesicles. The aim of this review was to evaluate the scientific literature on markers of BOS after lung transplant. We performed a systematic review to find all available data on potential prognostic and diagnostic markers of BOS.

Complement Activation in Patients With Heat-Related Illnesses: Soluble CD59 Is a Novel Biomarker Indicating Severity of Heat-Related Illnesses

Although multiple organ dysfunction syndrome (MODS) is the main cause of death in patients with heat-related illnesses, its underlying pathophysiological mechanism remains elusive. Complement activation is considered one of the main causes of MODS in patients with sepsis and trauma. Considering the pathophysiological similarity of heat related-illnesses with sepsis and trauma, the complement system might be activated in patients with heat-related illnesses as well. Our aim was to investigate whether excessive complement activation occurs in patients with heat-related illnesses.

Complement as driver of systemic inflammation and organ failure in trauma, burn, and sepsis

Complement is one of the most ancient defense systems. It gets strongly activated immediately after acute injuries like trauma, burn, or sepsis and helps to initiate regeneration. However, uncontrolled complement activation contributes to disease progression instead of supporting healing. Such effects are perceptible not only at the site of injury but also systemically, leading to systemic activation of other intravascular cascade systems eventually causing dysfunction of several vital organs. Understanding the complement pathomechanism and its interplay with other systems is a strict requirement for exploring novel therapeutic intervention routes. Ex vivo models exploring the cross-talk with other systems are rather limited, which complicates the determination of the exact pathophysiological roles that complement has in trauma, burn, and sepsis. Literature reporting on these three conditions is often controversial regarding the importance, distribution, and temporal occurrence of complement activation products further hampering the deduction of defined pathophysiological pathways driven by complement. Nevertheless, many in vitro experiments and animal models have shown beneficial effects of complement inhibition at different levels of the cascade. In the future, not only inhibition but also a complement reconstitution therapy should be considered in prospective studies to expedite how meaningful complement-targeted interventions need to be tailored to prevent complement augmented multi-organ failure after trauma, burn, and sepsis.

This review summarizes clinically relevant studies investigating the role of complement in the acute diseases trauma, burn, and sepsis with important implications for clinical translation.

[Predictors for the Bronchiolitis Obliterans Syndrome in Lung Transplant Patient]

肺移植是治疗终末期肺病的有效方法。目前，肺移植术后1年生存率已达到80%，由于闭塞性细支气管炎综合症（bronchiolitis obliterans syndrome, BOS）的发生，5年生存率维持在50%左右。BOS是一个纤维化的过程，最终导致不可逆的气道闭塞。缺血-再灌注损伤、感染、氧化应激以及急性排斥反应等多个因素参与了BOS的发生。研究证实BOS的早期诊断与预后良好相关。因此，寻找灵敏、特异的BOS预测标记物对于提高肺移植患者长期生存具有重要的科学和临床意义。本文就与BOS发生发展相关的免疫调节细胞、分泌性蛋白质、细胞膜蛋白等指标的变化在BOS早期诊断中的作用进行综述。

Inhibition of NADPH Oxidase-Derived Reactive Oxygen Species Decreases Expression of Inflammatory Cytokines in A549 Cells

Various experimental models strongly support the hypothesis that airway inflammation can be caused by oxidative stress. Inflammatory airway diseases like asthma and COPD are characterized by higher levels of ROS and inflammatory cytokines. One of the sources of ROS is NADPH oxidase. Therefore, the aim of the study was to investigate influence of NADPH oxidase inhibition on the expression of IL-6, IL-8, TNF, TSLP, CD59, and PPAR-γ in vitro. A549 cells were incubated with apocynin in three concentrations (0.5 mg/ml, 1 mg/ml, and 3 mg/ml). Cells were trypsinized and RNA isolated after 1 h, 2 h, and 4 h of apocynin incubation at each concentration. Afterwards, reverse transcription was performed to evaluate mRNA expression using real-time PCR. The time-response and dose-response study showed that apocynin significantly influenced the relative expression of chosen genes (IL-6, IL-8, TNF, PPAR-γ, TSLP, and CD59). Apocynin decreased the mRNA expression of TNF-α at all concentrations used, and of IL-6 at concentrations of 1 and 3 mg/ml (p < 0.05). TSLP mRNA expression was also reduced by apocynin after 1 h and 2 h, and CD59 mRNA after 1 h, but only at the highest concentration. The expression of PPAR-γ was reduced after apocynin in the highest concentrations only (p < 0.05). The results might suggest that proinflammatory agents’ expression levels are strongly connected to the presence of oxidative stress generated by NADPH oxidase and this might be at least partially eliminated by anti-oxidative action. Apocynin, as an effective inhibitor of NADPH oxidase, seems to be useful in potential anti-oxidative and anti-inflammatory therapy.

Serum CD59: a novel biomarker of idiopathic pulmonary fibrosis?

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is the most common among idiopathic interstitial pneumonia. Life expectancy is estimated around 3-5 years at diagnosis. No reliable prognostic biomarker has been approved for routinary clinical practice of IPF. The aim of this study is to investigate the potential prognostic value of serum CD59 in a cohort of IPF patients.

METHODS

Fifty-seven patients (45 males, 66.1±10 years old) were recruited in Siena Regional Referral Center for Interstitial Lung Disease and underwent serum sampling for CD59 detection during diagnostic pathway. Clinical, functional, radiological and survival data were retrospectively collected. As control group for CD59 values, we recruited eight healthy volunteers (five males, 59.2±18 years old).

RESULTS

CD59 levels were significantly higher in IPF patients in respect with healthy controls (P=0.0238). Patients with CD59 concentrations lower than 15 ng/mL reported a significant reduction of survival time (P=0.009); current or former smokers with CD59 <15 ng/mL showed the worst prognosis (P=0.014).

CONCLUSIONS

CD59 levels were significantly increased in IPF patients, supporting the existence of epithelial damage in the pathogenesis of disease. Lower values of CD59 were associated with a significantly worse prognosis, suggesting a potential role of CD59 in the prognostic estimation of IPF patients.

Single-cell RNA sequencing study of retinal immune regulators identified CD47 and CD59a expression in photoreceptors-Implications in subretinal immune regulation

The neuroretina is protected by its own defense system, that is microglia and the complement system. Under normal physiological conditions, microglial activation is tightly regulated by the neurons although the underlying mechanism remains elusive. Using published single-cell RNA sequencing data sets, we found that immune regulatory molecules including CD200, CD47, CX3CL1, TGFβ, and complement inhibitor CD59a are expressed by various retinal neurons. Importantly, we found that photoreceptors express higher levels of CD47 and CD59a, which was further confirmed in cultured 661W cells, WERI-Rb1 cells, and microdissected photoreceptors from human eyes. The expression of CD59a mRNA in 661W cells was upregulated by TNFα and hypoxia, whereas LPS, hypoxia, and IL-4 upregulated CD47 mRNA expression in 661W cells. Immunofluorescence staining detected strong CD59a immunoreactivity in the outer nuclear layer, inner/outer segments, and discrete staining in ganglion cell layer (GCL), inner plexiform layer (IPL), and outer plexiform layer. The expression of CD59a in photoreceptors was increased in the detached retina, but decreased in retinas from experimental autoimmune uveoretinitis (EAU) mice. In EAU retina, CD59a was highly expressed by active immune cells. CD47 was detected in GCL, IPL, and inner nuclear layer and some photoreceptors. The expression of CD47 in photoreceptors was also increased in the detached retina but decreased in EAU retina. In a coculture system, 661W enhanced arginase-1 and reduced IL-6 mRNA expression in BV2 microglial cells. Our results suggest that photoreceptors express immune regulatory molecules and may have the potential to regulate immune activation in the outer retina/subretinal space under pathophysiological conditions.

Blood CD9+ B cell, a biomarker of bronchiolitis obliterans syndrome after lung transplantation

Bronchiolitis obliterans syndrome is the main limitation for long-term survival after lung transplantation. Some specific B cell populations are associated with long-term graft acceptance. We aimed to monitor the B cell profile during early development of bronchiolitis obliterans syndrome after lung transplantation. The B cell longitudinal profile was analyzed in peripheral blood mononuclear cells from patients with bronchiolitis obliterans syndrome and patients who remained stable over 3 years of follow-up. CD24^hi CD38^hi transitional B cells were increased in stable patients only, and reached a peak 24 months after transplantation, whereas they remained unchanged in patients who developed a bronchiolitis obliterans syndrome. These CD24^hi CD38^hi transitional B cells specifically secrete IL-10 and express CD9. Thus, patients with a total CD9⁺ B cell frequency below 6.6% displayed significantly higher incidence of bronchiolitis obliterans syndrome (AUC = 0.836, PPV = 0.75, NPV = 1). These data are the first to associate IL-10-secreting CD24^hi CD38^hi transitional B cells expressing CD9 with better allograft outcome in lung transplant recipients. CD9-expressing B cells appear as a contributor to a favorable environment essential for the maintenance of long-term stable graft function and as a new predictive biomarker of bronchiolitis obliterans syndrome-free survival.

Altered Expression of Complement Regulatory Proteins CD35, CD46, CD55, and CD59 on Leukocyte Subsets in Individuals Suffering From Coronary Artery Disease

Studies conducted in animal models have suggested that membrane complement regulatory proteins play an important role in the pathophysiology of coronary artery disease (CAD). In this study, a total of 100 individuals, with stable CAD and 100 healthy controls, both groups predominantly male, were recruited. We evaluated the plasma levels of complement regulatory proteins (Cregs) CD35, CD46, CD55, and CD59 and their surface expression on granulocytes, lymphocytes, and monocytes by flow cytometry. The mRNA expression of these Cregs in total leukocytes was determined by quantitative PCR. The soluble forms of Cregs, C3c, Mannose binding protein-associated serine protease 2 (MASP-2), Platelet activating factor-acetyl hydrolase (PAF-AH), and inflammatory cytokines were quantified by ELISA. High plasma levels of C3c, indicative of complement activation, in addition to significantly low levels of Cregs, were observed in CAD patients. A significantly lower expression of CD46 and CD55 on the surface of lymphocytes, monocytes, and granulocytes and higher surface expression of CD35 and CD59 on granulocytes (p < 0.0001) was seen in CAD patients as compared to healthy donors. The high expression of CD59 on granulocytes positively correlated with the severity of disease and may serve as a potential marker of disease progression in CAD.

Early Identification of Chronic Lung Allograft Dysfunction: The Need of Biomarkers

A growing number of patients with end-stage lung disease have benefited from lung transplantation (LT). Improvements in organ procurement, surgical techniques and intensive care management have greatly increased short-term graft survival. However, long-term outcomes remain limited, mainly due to the onset of chronic lung allograft dysfunction (CLAD), whose diagnosis is based on permanent loss of lung function after the development of irreversible lung lesions. CLAD is associated with high mortality and morbidity, and its exact physiopathology is still only partially understood. Many researchers and clinicians have searched for CLAD biomarkers to improve diagnosis, to refine the phenotypes associated with differential prognosis and to identify early biological processes that lead to CLAD to enable an early intervention that could modify the inevitable degradation of respiratory function. Donor-specific antibodies are currently the only biomarkers used in routine clinical practice, and their significance for accurately predicting CLAD is still debated. We describe here significant studies that have highlighted potential candidates for reliable and non-invasive biomarkers of CLAD in the fields of imaging and functional monitoring, humoral immunity, cell-mediated immunity, allograft injury, airway remodeling and gene expression. Such biomarkers would improve CLAD prediction and allow differential LT management regarding CLAD risk.

Complement and Transplantation: From New Mechanisms to Potential Biomarkers and Novel Treatment Strategies

The complement system, traditionally considered a component of innate immunity, is now recognized as a crucial mediator of the adaptive immune response in solid organ transplantation. Preclinical and early human trials have demonstrated the importance of complement effector mechanisms in driving allograft injury during specific antigraft immune responses, including ischemia-reperfusion injury, T-cell-mediated rejection, and antibody-mediated rejection, as well as a potential role for complement-derived risk stratification biomarkers. These data support the need for further testing of complement inhibitors in solid organ transplant recipients.

Urinary proteome analysis of acute hypercoagulable state in rat model induced by ε-aminocaproic acid

The hypercoagulable state occurs in a group of prothrombotic disorders associated with an increased risk for thromboembolic events, but it is difficult to diagnose due to the lack of available biomarkers. This study aimed to investigate systematic changes of urinary proteome in acute hypercoagulable state induced by certain antifibrinolytics. To reduce the effects of both genetic and environmental factors on the urinary proteome, we used a rat model of acute hypercoagulable state induced by an antifibrinolytic agent ε-aminocaproic acid, resembling human hypercoagulable state. Urine samples were collected during acute hypercoagulable state for analysis by liquid chromatography-tandem mass spectrometry (LCMS/MS). Of 65 significantly changed proteins in acute hypercoagulable state, 38 proteins had human orthologs, and 18 proteins were identified as stable in normal human urine. None of the identified proteins have been found to be clotting factors, but 4 proteins are known to be involved in the regulation of blood coagulation factors. Two proteins were verified as the markers associated with acute hypercoagulable state by Western blot analysis. In addition, four common differential urinary proteins have been found in acute hypercoagulable state induced by another antifibrinolytics tranexamic acid. These four proteins are potential biomarkers for early diagnosis of hypercoagulable state to prevent the development of thrombotic diseases.

Molecular pathogenesis of human CD59 deficiency

Objective

To characterize all 4 mutations described for CD59 congenital deficiency.

Methods

The 4 mutations, p.Cys64Tyr, p.Asp24Val, p.Asp24Valfs*, and p.Ala16Alafs*, were described in 13 individuals with CD59 malfunction. All 13 presented with recurrent Guillain-Barré syndrome or chronic inflammatory demyelinating polyneuropathy, recurrent strokes, and chronic hemolysis. Here, we track the molecular consequences of the 4 mutations and their effects on CD59 expression, localization, glycosylation, degradation, secretion, and function. Mutants were cloned and inserted into plasmids to analyze their expression, localization, and functionality.

Results

Immunolabeling of myc-tagged wild-type (WT) and mutant CD59 proteins revealed cell surface expression of p.Cys64Tyr and p.Asp24Val detected with the myc antibody, but no labeling by anti-CD59 antibodies. In contrast, frameshift mutants p.Asp24Valfs* and p.Ala16Alafs* were detected only intracellularly and did not reach the cell surface. Western blot analysis showed normal glycosylation but mutant-specific secretion patterns. All mutants significantly increased MAC-dependent cell lysis compared with WT. In contrast to CD59 knockout mice previously used to characterize phenotypic effects of CD59 perturbation, all 4 hCD59 mutations generate CD59 proteins that are expressed and may function intracellularly (4) or on the cell membrane (2). None of the 4 CD59 mutants are detected by known anti-CD59 antibodies, including the 2 variants present on the cell membrane. None of the 4 inhibits membrane attack complex (MAC) formation.

Conclusions

All 4 mutants generate nonfunctional CD59, 2 are expressed as cell surface proteins that may function in non-MAC-related interactions and 2 are expressed only intracellularly. Distinct secretion of soluble CD59 may have also a role in disease pathogenesis.

CD59: a promising target for tumor immunotherapy

CD59 has been identified as a glycosylphosphatidylinositol-anchored membrane protein that acts as an inhibitor of the formation of the membrane attack complex to regulate complement activation. Recent studies have shown that CD59 is highly expressed in several cancer cell lines and tumor tissues. CD59 also regulates the function, infiltration and phenotypes of a variety of immune cells in the tumor microenvironment. Herein, we summarized recent advances related to the functions and mechanisms of CD59 in the tumor microenvironment. Therapeutic strategies that seek to modulate the functions of CD59 in the tumor microenvironment could be a promising direction for tumor immunotherapy.

High circulating CD4+CD25hiFOXP3+ T-cell sub-population early after lung transplantation is associated with development of bronchiolitis obliterans syndrome

BACKGROUND

Chronic bronchiolitis obliterans syndrome (BOS) remains a major limitation for long-term survival after lung transplantation. The immune mechanisms involved and predictive biomarkers have yet to be identified. The purpose of this study was to determine whether peripheral blood T-lymphocyte profile could predict BOS in lung transplant recipients.

METHODS

An in-depth profiling of CD4⁺ and CD8⁺ T cells was prospectively performed on blood cells from stable (STA) and BOS patients with a longitudinal follow-up. Samples were analyzed at 1 and 6 months after transplantation, at the time of BOS diagnosis, and at an intermediate time-point at 6 to 12 months before BOS diagnosis.

RESULTS

Although no significant difference was found for T-cell compartments at BOS diagnosis or several months beforehand, we identified an increase in the CD4⁺CD25^hiFoxP3⁺ T-cell sub-population in BOS patients at 1 and 6 months after transplantation (3.39 ± 0.40% vs 1.67 ± 0.22% in STA, p < 0.001). A CD4⁺CD25^hiFoxP3⁺ T-cell threshold of 2.4% discriminated BOS and stable patients at 1 month post-transplantation. This was validated on a second set of patients at 6 months post-transplantation. Patients with a proportion of CD4⁺CD25^hiFoxP3⁺ T cells up to 2.4% in the 6 months after transplantation had a 2-fold higher risk of developing BOS.

CONCLUSIONS

This study is the first to report an increased proportion of circulating CD4⁺CD25^hiFoxP3⁺ T cells early post-transplantation in lung recipients who proceed to develop BOS within 3 years, which supports its use as a BOS predictive biomarker.

Blood Gene Expression Predicts Bronchiolitis Obliterans Syndrome

Bronchiolitis obliterans syndrome (BOS), the main manifestation of chronic lung allograft dysfunction, leads to poor long-term survival after lung transplantation. Identifying predictors of BOS is essential to prevent the progression of dysfunction before irreversible damage occurs. By using a large set of 107 samples from lung recipients, we performed microarray gene expression profiling of whole blood to identify early biomarkers of BOS, including samples from 49 patients with stable function for at least 3 years, 32 samples collected at least 6 months before BOS diagnosis (prediction group), and 26 samples at or after BOS diagnosis (diagnosis group). An independent set from 25 lung recipients was used for validation by quantitative PCR (13 stables, 11 in the prediction group, and 8 in the diagnosis group). We identified 50 transcripts differentially expressed between stable and BOS recipients. Three genes, namely POU class 2 associating factor 1 (POU2AF1), T-cell leukemia/lymphoma protein 1A (TCL1A), and B cell lymphocyte kinase, were validated as predictive biomarkers of BOS more than 6 months before diagnosis, with areas under the curve of 0.83, 0.77, and 0.78 respectively. These genes allow stratification based on BOS risk (log-rank test p < 0.01) and are not associated with time posttransplantation. This is the first published large-scale gene expression analysis of blood after lung transplantation. The three-gene blood signature could provide clinicians with new tools to improve follow-up and adapt treatment of patients likely to develop BOS.

Update in Chronic Lung Allograft Dysfunction

Chronic lung allograft dysfunction (CLAD) is the major limitation to posttransplant survival. This review highlights the evolving definition of CLAD, risk factors, treatment, and expected outcomes after the development of CLAD.