Linking clinical phenotypes of chronic lung allograft dysfunction to changes in lung structure.

Chronic lung allograft dysfunction (CLAD) remains the major barrier to long-term success after lung transplantation. This report compares gross and microscopic features of lungs removed from patients receiving a redo-transplant as treatment for CLAD. Lungs donated by patients with either the bronchiolitis obliterans syndrome (BOS) or restrictive allograft syndrome (RAS) phenotype of CLAD and appropriate control lungs (eight per group) were air-inflated, frozen solid and kept frozen while a multi-detector computed tomography (MDCT) was obtained. The lung was then cut into 2-cm thick transverse slices and sampled for micro-CT and histopathology. The MDCT showed reduced lung volume with increased lung weight and density in RAS versus BOS and control (p<0.05). Although pre-terminal bronchioles were obstructed in both phenotypes, RAS lungs showed a reduction of pre-terminal bronchioles (p<0.01). Micro-CT and matched histopathology showed that RAS was associated with reduced numbers of terminal bronchioles/lung compared to BOS and controls (p<0.01), with expansion of the interstitial compartment and obliteration of the alveolar airspaces by fibrous connective tissue. RAS is associated with greater destruction of both pre-terminal and terminal bronchioles. Additionally, the interstitial compartments are expanded and alveolar airspaces are obliterated by accumulation of fibrous connective tissue.

Innate and adaptive interleukin-17-producing lymphocytes in chronic inflammatory lung disorders.

During T-cell receptor activation in a particular cytokine environment, naive CD4+ T cells may differentiate into lineages defined by their pattern of cytokine production and transcription factors: T helper type 1 (Th1), Th2, Th17, and Th22 cells; follicular helper T cells; and inducible regulatory T cells. Th17 cells have been recognized as a distinct lineage of Th cells, and associations between IL-17 and human disease have been known somewhat longer. It would be an oversimplification to restrict IL-17 to Th17 cells. Indeed, IL-17 is also expressed by other cells including IL-17-producing γδ T (γδ T-17) cells, natural killer T-17 cells, and IL-17-producing lymphoid tissue-induced cells. IL-17 was cloned in 1995 as a cytokine expressed by T cells, exerting inflammatory effects on epithelial, endothelial, and fibroblast cells. IL-17 is a solid link between innate and adaptive immunity and can exert both beneficial and deleterious effects. The discovery of IL-17 T cells has provided exciting new insights into host defense, immunoregulation, and autoimmunity. Unquestionably, data from mouse models have contributed enormously to our insight into immunological mechanisms. However, because of numerous differences between murine and human immunology, data obtained in mice are not simply interchangeable. We review IL-17 T cells exclusively in the human situation and more specifically their potential role in respiratory diseases. The advances in our understanding of IL-17 regulation offer opportunities to dissect the human IL-17 system and to reflect on the clinical presentation of lung diseases. More importantly, the IL-17 system allows us to speculate on new therapeutic opportunities. Some results have been previously reported in an abstract.

Arterial Vasoreactivity is Equally Affected by In Vivo Cross-Clamping with Increasing Loads in Young and Middle-Aged Mice Aortas.

PURPOSE: To compensate for the lack of haptic feedback by surgical robots, limitation of exerted forces could be implemented. The limits should be based on the observed relationship between tissue load and induced damage. This study examines whether age-related changes influence this relationship. METHODS: Descending thoracic aortas of male C57BL/6J mice of 10, 25 and 40 weeks were clamped in vivo (no clamp, 0.5N or 2.0N) for 2 min. Functional integrity was tested in vitro by studying endothelium-dependent and -independent vasoreactivity. RESULTS: Endothelium-dependent relaxation deteriorated with increased clamping force at all ages. Clamping did not influence endothelium-independent vasodilation. Age (10, 25 and 40 weeks) did not significantly impact on the effect of clamping on endothelium-dependent and independent vasoreactivity. CONCLUSIONS: Within the tested conditions, mechanical clamping induces damage to the vascular endothelium, but not to the smooth muscle cells. Age has no effect on the obtained results in mice from 10 to 40 weeks old.

Atherosclerosis Alters Loading-Induced Arterial Damage: Implications for Robotic Surgery.

BACKGROUND: Lack of intra-operative haptic information during robotic surgery increases the risk for unintended tissue overload and damage. Knowledge about the acute and chronic fundamental relationship between force load and induced damage in healthy and diseased arteries is crucial to enable intra-operative haptic feedback or shared autonomy and improve patient safety. METHODS: Arteries of wildtype and atherosclerotic mice were clamped in vivo for 2 minutes (0.0N, 0.6N or 1.27N). Histological analysis (Verhoeff's-Van Gieson, Osteopontin, CD45, CD105) was performed immediately, or after 6 hours, 2 weeks or 1 month. Endothelium-dependent and-independent vasodilatation was assessed immediately or 1 month after clamping. RESULTS: Endothelium dependent vasodilatation is worse after clamping of wildtype arteries, but is restored after one month. Clamping also results in flattening of the innermost elastic membrane of both genotypes, which is reversed over time for wildtype arteries but not for vessels from atherosclerotic mice. Higher osteopontin content in wildtype and LDLR-/- mice after 2 weeks suggests a phenotypic switch of the medial smooth muscle cells (SMCs), an effect that is reversed after 1 month. While inflammation in the intima diminishes, medial CD45 content rises through time in both genotypes. CD105 staining shows that even manipulation without clamping results in endothelial cell loss in both LDLR+/+ and LDLR-/- mice. CONCLUSIONS: Arterial clamping induces different acute and long-term injury to the vessel wall of atherosclerotic and healthy arteries.

Enhanced ß-adrenergic cardiac reserve in Trpm4⁻/⁻ mice with ischaemic heart failure.

AIMS: Heart failure (HF) is a complex syndrome characterized by critically reduced cardiac contractility and function. We have shown previously that Transient Receptor Potential Melastatin 4 protein (TRPM4) functions as a Ca(2+)-activated non-selective cation channel and constitutes a novel regulator of ventricular contractility. In healthy Trpm4-deficient (Trpm4(-/-)) mice, we observed increased cardiac contractile function after ß-adrenergic stimulation. In the current study, cardiac performance was examined in wild-type (WT) and Trpm4(-/-) mice with severe ischaemic HF. METHODS AND RESULTS: Myocardial infarction (MI) was induced in WT and Trpm4(-/-) C57Bl6/N mice by ligation of the left anterior descending artery. During the first week after MI, mortality was higher in WT mice. Both groups showed similar infarct-typical ECG patterns during follow-up period. After 10 weeks, reduced ejection fraction and severe dilatation, determined by cardiac MRI, confirmed the development of HF in both genotypes. In vivo pressure-conductance analysis revealed no differences in cardiac contractility in basal conditions. However, during ß-adrenergic stimulation, cardiac performance was significantly different between WT and Trpm4(-/-) mice. In contrast to increasing contractility in Trpm4(-/-) mice, WT mice showed a deteriorated cardiac performance. Also 30% of WT animals died during isoprenaline infusion vs. no Trpm4(-/-) mice. Infarct size, determined post mortem, was equal in WT and Trpm4(-/-) hearts. CONCLUSION: Deletion of the Trpm4 gene in mice improved survival and significantly enhanced ß-adrenergic cardiac reserve after inducing ischaemic HF. This suggests that pharmacological or genetic down-regulation of TRPM4 function might be a novel strategy in the management of HF.

Platelet endothelial aggregation receptor-1: a novel modifier of neoangiogenesis.

AIMS: Platelet endothelial aggregation receptor-1 (PEAR1) is a cell membrane protein, expressed on platelets and endothelial cells (ECs). PEAR1 sustains αIIbß3 activation in aggregating platelets and attenuates megakaryopoiesis via controlling the degree of Akt phosphorylation. Its role in EC biology is unknown. The aim of this study was to determine the expression of PEAR1 in the human endothelium of various tissues and to investigate its role in ECs in vitro and in angiogenesis, using Pear1(-/-) mice. METHODS AND RESULTS: PEAR1 is present on the membrane and on filo- and lamellipodia of human cultured ECs, and its expression coincides with CD31 in various tissues. PEAR1 expression is variable in ECs of different origin. Lentiviral knockdown of PEAR1 in cultured ECs doubled EC proliferation and significantly stimulated EC migration, in turn enhancing in vitro tube formation on matrigel through the Akt/PTEN-dependent p21/CDC2 pathway. Even when physiological blood vessel formation was unaffected in Pear1(-/-) mice, neoangiogenesis in these mice was significantly increased both in a hind limb ischaemia ligation model [4.7-fold increase in capillary density in the ligated limb of Pear1(-/-) mice compared with ligated limbs in wild-type (WT) mice] and in a skin wound-healing model, resulting in a two-fold faster wound closure in Pear1(-/-) mice compared with WT littermates. CONCLUSION: We established an inverse correlation between endothelial PEAR1 expression and vascular assembly both in vitro and in vivo. These findings identify PEAR1 as a novel modifier of neoangiogenesis.

Hematopoietic stem/progenitor cell proliferation and differentiation is differentially regulated by high-density and low-density lipoproteins in mice.

RATIONALE: Hematopoietic stem/progenitor cells (HSPC) are responsible for maintaining the blood system as a result of their self-renewal and multilineage differentiation capacity. Recently, studies have suggested that HDL cholesterol may inhibit and impaired cholesterol efflux may increase HSPC proliferation and differentiation. OBJECTIVES: We hypothesized that LDL may enhance HSPC proliferation and differentiation while HDL might have the opposing effect which might influence the size of the pool of inflammatory cells. METHODS AND RESULTS: HSPC number and function were studied in hypercholesterolemic LDL receptor knockout (LDLr(-/-)) mice on high fat diet. Hypercholesterolemia was associated with increased frequency of HSPC, monocytes and granulocytes in the peripheral blood (PB). In addition, an increased proportion of BM HSPC was in G(2)M of the cell cycle, and the percentage of HSPC and granulocyte-macrophage progenitors (GMP) increased in BM of LDLr(-/-) mice. When BM Lin-Sca-1+cKit+ (i.e. "LSK") cells were cultured in the presence of LDL in vitro we also found enhanced differentiation towards monocytes and granulocytes. Furthermore, LDL promoted lineage negative (Lin-) cells motility. The modulation by LDL on HSPC differentiation into granulocytes and motility was inhibited by inhibiting ERK phosphorylation. By contrast, when mice were infused with human apoA-I (the major apolipoprotein of HDL) or reconstituted HDL (rHDL), the frequency and proliferation of HSPC was reduced in BM in vivo. HDL also reversed the LDL-induced monocyte and granulocyte differentiation in vitro. CONCLUSION: Our data suggest that LDL and HDL have opposing effects on HSPC proliferation and differentiation. It will be of interest to determine if breakdown of HSPC homeostasis by hypercholesterolemia contributes to inflammation and atherosclerosis progression.

Vitamin D deficiency in lung transplant patients: is it important?

BACKGROUND: Vitamin D deficiency has been reported in different chronic pulmonary diseases like asthma and chronic obstructive pulmonary disease, but little is known in lung transplant recipients. METHODS: Serum 25-hydroxyvitamin D (25-OHD) levels and pulmonary function (forced expiratory volume in 1 sec [FEV(1)] %predicted) were measured in 131 lung transplant patients during their yearly posttransplant check-up hospital stay, and the total number of infections and perivascular/peribronchiolar rejections were assessed from transplantation on. RESULTS: Vitamin D deficiency (<30 ng/mL) occurred in 62 of 131 patients (47.3%), of whom 26 (19.8%) were severely deficient (<20 ng/mL). The FEV(1) was significantly lower in the deficient group compared with the group with normal levels (P=0.019). Moreover, we could find an association between FEV(1) and 25-OHD levels in univariate analysis (P=0.018), which remained significant in multivariate analysis (P=0.012). The same holds true for the association between 25-OHD levels and the peak postoperative FEV(1) (P=0.021 in multivariate analysis). We also identified significantly more patients with moderate to severe B-grade rejections in the deficient group (P=0.0038). CONCLUSION: Vitamin D deficiency is present in 47% of our lung transplant patients and seems independently associated with a lower FEV(1) and more severe B-grade rejections. This study raises the potential need for additional vitamin D treatment in lung transplantation and clearly indicates the role of a randomized placebo-controlled trial with vitamin D supplementation, which is ongoing in our center.