Die Rolle der IFN-gamma Signalübertragung und von MyD88 in der Angiotensin-II-induzierten vaskulären Dysfunkion, Inflammation und arteriellen Hypertonie

Im Rahmen dieser Arbeit wurde die Rolle von myelomonozytären Zellen, IFN-gamma (Interferon gamma), MyD88 (myeloid differentiation factor 88) und zugrundeliegenden Signalwege in der Angiotensin II (ATII)-induzierten vaskulären Inflammation, Dysfunktion und arteriellen Hypertonie untersucht. Wie bereits veröffentlichte Vordaten aus meiner Arbeitsgruppe zeigten, schützt die Depletion von Lysozym M (LysM)+ myelomonozytären Zellen (Diphteriatoxin-vermittelt in Mäusen, die transgen für den humanen Diphtheriatoxin-Rezeptor sind, LysMiDTR Mäuse) vor der ATII-induzierten vaskulären Dysfunktion und arterieller Hypertonie, und kann durch adoptiven Zelltransfer von Wildtyp Monozyten wiederhergestellt werden. In meiner Arbeit konnte ich zeigen, dass die Rekonstitution von Monozyten-depletierten LysMiDTR Mäusen mit Wildtyp Monozyten den Phänotyp der vaskulären Dysfunktion wiederherstellen kann, die Rekonstitution mit gp91phox-/y oder Agtr1-/- Monozyten jedoch nicht. Die Hypertonus-mediierenden Effekte dieser infiltrierenden Monozyten scheinen demnach von der intakten ATII und NADPH Oxidase Signalübertragung in diesen Zellen abhängig zu sein. Vermutlich ebenfalls für die Aktivierung der Monozyten funktionell wichtig sind IFN-gamma, produziert durch NK-Zellen, und der Transkriptionsfaktor T-bet (T-box expressed in T cells), exprimiert von NK-Zellen und Monozyten. IFN-gamma-/- Mäuse waren partiell geschützt vor der ATII-induzierten vaskulären Dysfunktion und charakterisiert durch reduzierte Level an Superoxid im Gefäß im Vergleich zu ATII-infundierten Wildtyp Mäusen. IFN-gamma-/- und T-bet defiziente Tbx21-/- Mäuse zeichneten sich ferner durch eine reduzierte ATII-mediierte Rekrutierung von NK1.1+ NK-Zellen, als ein Hautproduzent von IFN-gamma, sowie CD11b+GR-1low Interleukin-12 (IL-12) kompetenten Monozyten aus. Durch Depletions- und adoptive Transferexperimente konnte ich in dieser Arbeit NK-Zellen als essentielle Mitstreiter in der vaskulären Dysfunktion identifizieren und stellte fest, dass T-bet+LysM+ myelomonozytäre Zellen für die NK-Zellrekrutierung in die Gefäßwand und lokale IFN-gamma Produktion benötigt werden. Damit wurde erstmals NK-Zellen eine essentielle Rolle in der ATII-induzierten vaskulären Dysfunktion zugeschrieben. Außerdem wurde der T-bet-IFN-gamma Signalweg und die gegenseitige Monozyten-NK-Zellaktivierung als ein potentielles therapeutisches Ziel in kardiovaskulären Erkrankungen aufgedeckt. Des Weiteren identifizierte ich in meiner Arbeit MyD88 als ein zentrales Signalmolekül in der ATII-getriebenen Inflammation und vaskulären Gefäßschädigung. MyD88 Defizienz reduzierte den ATII-induzierten Anstieg des systolischen Blutdrucks und die endotheliale und glattmuskuläre vaskuläre Dysfunktion. Zusätzlich waren die vaskuläre Superoxid-Bildung sowie die Expressionslevel der NADPH Oxidase, der wichtigsten Quelle für oxidativem Stress im Gefäß, in ATII-infundierten MyD88-/- Mäusen im Vergleich zum Wildtyp reduziert. Mit Hilfe von durchflusszytometrischen Analysen deckte ich zudem auf, dass die ATII-induzierte Einwanderung von CD45+ Leukozyten, insbesondere CD11b+Ly6G-Ly6Chigh inflammatorischen Monozyten in MyD88-/- Mäusen signifikant abgeschwächt war. Diese Resultate wurden durch immunhistochemische Untersuchung von Aortengewebe auf CD68+, F4/80+ und Nox2+ Makrophagen/Phagozyten sowie Expressionsanalysen von Inflammationsmarkern untermauert. Analysen der mRNA Expression in Aortengewebe zeigten ferner eine in Wildtyp Mäusen nach ATII Infusion tendenziell gesteigerte Expression von inflammatorischen Monozytenmakern sowie eine abnehmende Expression von reparativen Monozytenmarken, während dieser Shift zu einem proinflammatorsichen Phänotyp in MyD88-/- blockiert zu sein schien. Dies zeigt eine Rolle von MyD88 in der terminalen Differenzierung von myelomonozytären Zellen an. Um dies weitergehend zu untersuchen und aufzudecken, ob die MyD88 Effekte abhängig sind von Zellen der hämatopoetischen Linie oder Gewebszellen, wurden Knochenmarktransferexperimente durchgeführt. MyD88 Defizienz in Knochenmark-abstammende Zellen reduzierte die ATII-induzierte vaskuläre Dysfunktion und Infiltration der Gefäßwand mit CD45+ Leukozyten und inflammatorischen myelomonozytären Zellen. Die protektiven Effekte der MyD88 Defizienz in der Angiotensin II-induzierten Inflammation konnten nicht auf Signalwege über die Toll-like Rezeptoren TLR2, -7 oder -9 zurückgeführt werden, wie die Untersuchung der vaskulären Reaktivität entsprechender Knockout Mäuse zeigte. Zusammenfassend konnte ich in meiner Arbeit zeigen, dass die Infiltration der Gefäßwand mit Nox2+AT1R+T-bet+MyD88+ myelomonozytären Zellen und die Wechselwirkung und gegenseitige Aktivierung dieser Zellen mit IFN-gamma produzierenden NK-Zellen eine zentrale Bedeutung in der Pathogenese der Angiotensin II (ATII)-induzierten vaskulären Dysfunktion, Inflammation und arteriellen Hypertonie einnehmen.

Rapid spontaneous malignant progression of supratentorial tanycytic ependymoma with sarcomatous features - "Ependymosarcoma"

By analogy to gliosarcoma, the term "ependymosarcoma" has recently been coined to thematize the rare phenomenon of a malignant mesenchymal component arising within an ependymoma. We report on an example of this paradigm, involving tanycytic ependymoma as the host tumor in a 40-year-old female who underwent two tumor extirpation procedures at one-year interval. She first presented with severe headaches, and was seen by imaging to harbor a moderately enhancing mass 2.5cm in diameter at the rostral septum pellucidum accompanied by occlusive hydrocephalus. Microscopically, the tumor consisted of solid, wavy fascicles of elongated cells that were occasionally interrupted by vague perivascular pseudorosettes. Mitotic activity was absent, and less than 1% of nuclei immunoreacted for MIB-1. A histological diagnosis of tanycytic ependymoma (WHO grade II) was rendered, and no adjuvant therapy given. At recurrence, the lesion was 3.5cm in diameter, intensely enhancing, and had already seeded into the subarachnoid space. Histology showed a biphasic glial-sarcomatous architecture with remnants of the original ependymoma now displaying hypercellularity and atypical - yet not frankly anaplastic - features. The sarcomatous moiety consisted of spindle and epithelioid cells densely interwoven with reticulin fibers. While the ependymal component was GFAP and S100 protein positive, and featured punctate staining for EMA, none of these markers was expressed in the adjacent sarcoma. Instead, the latter reacted for vimentin and smooth muscle actin. To the best of our knowledge, this is the first documentation of tanycytic ependymoma undergoing malignant transformation, one driven by a highly anaplastic mesenchymal component, corresponding to "ependymosarcoma".

MODELING THE DYNAMICS OF AIRWAY CONSTRICTION: EFFECTS OF AGONIST TRANSPORT AND BINDING

Recent advances have revealed that during exogenous airway challenge, airway diameters can not be adequately predicted by their initial diameters. Furthermore, airway diameters can also vary greatly in time on scales shorter than a breath. In order to better understand these phenomena, we developed a multiscale model which allows us to simulate aerosol challenge in the airways during ventilation. The model incorporates agonist-receptor binding kinetics to govern the temporal response of airway smooth muscle (ASM) contraction on individual airway segments, which together with airway wall mechanics, determines local airway caliber. Global agonist transport and deposition is coupled with pressure-driven flow, linking local airway constrictions with global flow dynamics. During the course of challenge, airway constriction alters the flow pattern, redistributing agonist to less constricted regions. This results in a negative feedback which may be a protective property of the normal lung. As a consequence, repetitive challenge can cause spatial constriction patterns to evolve in time, resulting in a loss of predictability of airway diameters. Additionally, the model offers new insight into several phenomena including the intra- and inter-breath dynamics of airway constriction throughout the tree structure.

Estrogen receptor- but not - or GPER inhibits high glucose-induced human VSMC proliferation: potential role of ROS and ERK

The decreased incidence of cardiovascular disease in premenopausal women has been attributed, at least partially, to protective effects of estrogens. However, premenopausal women with diabetes mellitus are no longer selectively protected. High-glucose (HG) conditions have previously been shown to abolish the antimitogenic effects of 17β-estradiol (E(2)) in vascular smooth muscle cells (VSMCs).

Resveratrol reduces myofibroblast arrhythmogenicity

Background: Among grape skin polyphenols, trans-resveratrol (RES) has been reported to slow the development of cardiac fibrosis and to affect myofibroblast (MFB) differentiation. Because MFBs induce slow conduction and ectopic activity following heterocellular gap junctional coupling to cardiomyocytes, we investigated whether RES and its main metabolites affect arrhythmogenic cardiomyocyte-MFB interactions. Methods: Experiments were performed with patterned growth strands of neonatal rat ventricular cardiomyocytes coated with cardiac MFBs. Impulse propagation characteristics were measured optically using voltage-sensitive dyes. Long-term video recordings served to characterize drug-related effects on ectopic activity. Data are given as means ± S.D. (n = 4–20). Results: Exposure of pure cardiomyocyte strands to RES at concentrations up to 10 µmol/L had no significant effects on impulse conduction velocity (θ) and maximal action potential upstroke velocities (dV/dtmax). By contrast, in MFB-coated strands exhibiting slow conduction, RES enhanced θ with an EC50 of ~10 nmol/L from 226 ± 38 to 344 ± 24 mm/s and dV/dtmax from 48 ± 7 to 69 ± 2%APA/ms, i.e., to values of pure cardiomyocyte strands (347 ± 33 mm/s; 75 ± 4%APA/ms). Moreover, RES led to a reduction of ectopic activity over the course of several hours in heterocellular preparations. RES is metabolized quickly in the body; therefore, we tested the main known metabolites for functional effects and found them similarly effective in normalizing conduction with EC50s of ~10 nmol/L (3-OH-RES), ~20 nmol/L (RES-3-O-β-glucuronide) and ~10 nmol/L (RES-sulfate), respectively. At these concentrations, neither RES nor its metabolites had any effects on MFB morphology and α-smooth muscle actin expression. This suggests that the antiarrhythmic effects observed were based on mechanisms different from a change in MFB phenotype. Conclusions: The results demonstrate that RES counteracts MFB-dependent arrhythmogenic slow conduction and ectopic activity at physiologically relevant concentrations. Because RES is rapidly metabolized following intestinal absorption, the finding of equal antiarrhythmic effectiveness of the main RES metabolites warrants their inclusion in future studies of potentially beneficial effects of these substances on the heart.

The effects of PTK787/ZK222584, an inhibitor of VEGFR and PDGFR? pathways, on intussusceptive angiogenesis and glomerular recovery from Thy1.1 nephritis

The aim of our study was to investigate the phenomenon of intussusceptive angiogenesis with a focus on its molecular regulation by vascular endothelial growth factor receptor (VEGFR)/platelet-derived growth factor receptor β (PDGFRβ) pathways and biological significance for glomerular recovery after acute injury. Glomerular healing by intussusception was examined in a particular setting of Thy1.1 nephritis, where the lysis of mesangial cells results in an initial collapse and successive rebuilding of glomerular capillary structure. Restoration of capillary structure after induction of Thy1.1 nephritis occurred by intussusceptive angiogenesis resulting in i) rapid expansion of the capillary plexus with reinstatement of the glomerular filtration surface and ii) restoration of the archetypical glomerular vascular pattern. Glomerular capillaries of nephritic rats after combined VEGFR2 and PDGFRβ inhibition by PTK787/ZK222584 (PTK/ZK) were tortuous and irregular. However, the onset of intussusceptive angiogenesis was influenced only after long-term PTK/ZK treatment, providing an important insight into differential molecular regulation between sprouting and intussusceptive angiogenesis. PTK/ZK treatment abolished α-smooth muscle actin and tensin expression by injured mesangial cells, impaired glomerular filtration of microspheres, and led to the reduction of glomerular volume and the presence of multiple hemorrhages detectable in the tubular system. Collectively, treatment of nephritic patients with PTK/ZK compound is not recommended.

Meningial perineurioma: a benign peripheral nerve sheath tumor in a previously unrecognized central nervous system location, mimicking meningioma

Perineurioma is an uncommon, mostly benign, spindle-cell tumor of peripheral nerve sheath origin with a predilection for the soft tissues. Although increasing awareness points to the sites of involvement by perineurioma possibly being as ubiquitous as those frequented by schwannian tumors, only one intracerebral example has been described to date. We report on a surgically resected perineurioma of the falx cerebri in an 86-year-old woman. Preoperative imaging showed an enhancing extraaxial mass of 6 cm × 5.7 cm × 3.7 cm. Histologically, the tumor consisted of a proliferation of spindle cells interwoven by a lattice of basal lamina. Alongside a prevailing soft tissue perineurioma pattern, sclerosing and reticular areas were seen as well. Tumor cells coexpressed EMA and GLUT-1, and a minority immunoreacted for smooth muscle actin. Pericellular basal lamina was decorated with collagen type IV. No staining for S100 protein was detected. Mitotic activity was virtually absent, and the MIB1 labeling index averaged 2%. Ultrastructural examination revealed abundant pinocytotic vesicles within and conspicuous tight junctions between slender cytoplasmic processes which, in turn, were encased by discontinuous basal lamina. FISH analysis confirmed loss of at least part of one chromosome 22q. This observation calls attention to perineurioma as a novel item in the repertoire of low-grade meningial spindle cell neoplasms, in the differential diagnostic context of which it is apt to being misconstrued as either meningioma, solitary fibrous tumor, or neurofibroma. Confusion with the latter bears the risk of overgrading innocuous features of perineurioma as criteria for malignancy.

Cancer therapy modulates VEGF signaling and viability in adult rat cardiac microvascular endothelial cells and cardiomyocytes

This work was motivated by the incomplete characterization of the role of vascular endothelial growth factor-A (VEGF-A) in the stressed heart in consideration of upcoming cancer treatment options challenging the natural VEGF balance in the myocardium. We tested, if the cytotoxic cancer therapy doxorubicin (Doxo) or the anti-angiogenic therapy sunitinib alters viability and VEGF signaling in primary cardiac microvascular endothelial cells (CMEC) and adult rat ventricular myocytes (ARVM). ARVM were isolated and cultured in serum-free medium. CMEC were isolated from the left ventricle and used in the second passage. Viability was measured by LDH-release and by MTT-assay, cellular respiration by high-resolution oxymetry. VEGF-A release was measured using a rat specific VEGF-A ELISA-kit. CMEC were characterized by marker proteins including CD31, von Willebrand factor, smooth muscle actin and desmin. Both Doxo and sunitinib led to a dose-dependent reduction of cell viability. Sunitinib treatment caused a significant reduction of complex I and II-dependent respiration in cardiomyocytes and the loss of mitochondrial membrane potential in CMEC. Endothelial cells up-regulated VEGF-A release after peroxide or Doxo treatment. Doxo induced HIF-1α stabilization and upregulation at clinically relevant concentrations of the cancer therapy. VEGF-A release was abrogated by the inhibition of the Erk1/2 or the MAPKp38 pathway. ARVM did not answer to Doxo-induced stress conditions by the release of VEGF-A as observed in CMEC. VEGF receptor 2 amounts were reduced by Doxo and by sunitinib in a dose-dependent manner in both CMEC and ARVM. In conclusion, these data suggest that cancer therapy with anthracyclines modulates VEGF-A release and its cellular receptors in CMEC and ARVM, and therefore alters paracrine signaling in the myocardium.

Paracrine effects of mesenchymal stem cells enhance vascular regeneration in ischemic murine skin

New theories on the regeneration of ischemic vasculature have emerged indicating a pivotal role of adult stem cells. The aim of this study was to investigate homing and hemodynamic effects of circulating bone marrow-derived mesenchymal stem cells (MSCs) in a critically ischemic murine skin flap model. Bone marrow-derived mesenchymal stem cells (Lin(-)CD105(+)) were harvested from GFP(+)-donor mice and transferred to wildtype C57BL/6 mice. Animals receiving GFP(+)-fibroblasts served as a control group. Laser scanning confocal microscopy and intravital fluorescence microscopy were used for morphological analysis, monitoring and quantitative assessment of the stem cell homing and microhemodynamics over two weeks. Immunohistochemical staining was performed for GFP, eNOS, iNOS, VEGF. Tissue viability was analyzed by TUNEL-assay. We were able to visualize perivascular homing of MSCs in vivo. After 4 days, MSCs aligned along the vascular wall without undergoing endothelial or smooth muscle cell differentiation during the observation period. The gradual increase in arterial vascular resistance observed in the control group was abolished after MSC administration (P<0.01). At capillary level, a strong angiogenic response was found from day 7 onwards. Functional capillary density was raised in the MSC group to 197% compared to 132% in the control group (P<0.01). Paracrine expression of VEGF and iNOS, but not eNOS could be shown in the MSC group but not in the controls. In conclusion, we demonstrated that circulating bone marrow-derived MSCs home to perivascular sites in critically ischemic tissue, exhibits paracrine function and augment microhemodynamics. These effects were mediated through arteriogenesis and angiogenesis, which contributed to vascular regeneration.

Huge aneurysm of the ascending aorta in a patient with adult-type Pompe's disease: histological findings mimicking fibrillinopathy

Adult-type Pompe's disease (glycogen storage disease type II) has rarely been shown to present with dilatative arteriopathy, suggesting potential smooth muscle involvement in addition to lysosomal glycogen deposits usually restricted to skeletal muscle tissue. We report the case of a middle-aged man under enzyme replacement therapy presenting with an exceedingly large thoracic aortic aneurysm. Surprisingly, the histological work-up of resected aortic tissue revealed changes mimicking those observed in patients with classic connective tissue diseases. Enzyme replacement therapy, in addition to musculoskeletal and pulmonary treatment for patients with Pompe's disease, may prolong survival and lead to patients presenting with vascular alterations that may pose surgical and potential diagnostic challenges in the future.

Sarcomatous evolution of oligodendroglioma ("oligosarcoma"): confirmatory report of an uncommon pattern of malignant progression in oligodendroglial tumors

By analogy to gliosarcoma, the neologism "oligosarcoma" is to describe an uncommon form of biphasic central nervous system tumor composed of contiguous neuroepithelial and mesenchymal elements, each of which individually meet the criteria of oligodendroglioma and sarcoma, respectively. By virtue of its distinctive genotype (codeletion 1p/19q), oligodendroglioma is a particularly inviting paradigm to test the assumption that such mixed tumors are clonally derived from a glial primary. We observed this constellation in a 41-year-old male who underwent two resection procedures for a recurring right frontal tumor at five years' interval. On imaging, both lesions were contrast-enhancing, and measured 7 cm × 7 cm × 6.8 cm and 7 cm × 6.5 cm × 4cm, respectively. Following the first operation, temozolomide monotherapy was administered. Whereas initial histology showed conventional anaplastic oligodendroglioma, the recurrence consisted mostly of a fibrosarcoma-like, fascicular neoplasm that was immunoreactive for vimentin, smooth muscle actin, S100 protein, and focally epithelial membrane antigen. In between, a subset of otherwise indistinguishable spindle cells expressed GFAP, and focally merged with residues of oligodendroglioma. Molecular testing for loss of heterozygosity confirmed codeletion of 1p/19q in both the primary tumor and the sarcomatous recurrence. Similarly, generalized immunoreactivity for the mutant R132H form of isocitrate dehydrogenase in both lesions indicated an identical mutation of the IDH1 gene. By the above standards, biologically consistent "oligosarcomas" are felt to be exceedingly rare, and possibly participate of a nosologically heterogeneous group of combined glial/mesenchymal lesions that may also include iatrogenically induced second malignancies as well as true collision tumors.

The Emerging Role of TLR and Innate Immunity in Cardiovascular Disease

Cardiovascular disease is a complex disorder involving multiple pathophysiological processes, several of which involve activation of toll-like receptors (TLRs) of the innate immune system. As sentinels of innate immunity TLRs are nonclonally germline-encoded molecular pattern recognition receptors that recognize exogenous as well as tissue-derived molecular dangers signals promoting inflammation. In addition to their expression in immune cells, TLRs are found in other tissues and cell types including cardiomyocytes, endothelial and vascular smooth muscle cells. TLRs are differentially regulated in various cell types by several cardiovascular risk factors such as hypercholesterolemia, hyperlipidemia, and hyperglycemia and may represent a key mechanism linking chronic inflammation, cardiovascular disease progression, and activation of the immune system. Modulation of TLR signaling by specific TLR agonists or antagonists, alone or in combination, may be a useful therapeutic approach to treat various cardiovascular inflammatory conditions such as atherosclerosis, peripheral arterial disease, secondary microvascular complications of diabetes, autoimmune disease, and ischemia reperfusion injury. In this paper we discuss recent developments and current evidence for the role of TLR in cardiovascular disease as well as the therapeutic potential of various compounds on inhibition of TLR-mediated inflammatory responses.

TRPM4 channels in the cardiovascular system: physiology, pathophysiology, and pharmacology

The transient receptor potential channel (TRP) family comprises at least 28 genes in the human genome. These channels are widely expressed in many different tissues, including those of the cardiovascular system. The transient receptor potential channel melastatin 4 (TRPM4) is a Ca(2+)-activated non-specific cationic channel, which is impermeable to Ca(2+). TRPM4 is expressed in many cells of the cardiovascular system, such as cardiac cells of the conduction pathway and arterial and venous smooth muscle cells. This review article summarizes the recently described roles of TRPM4 in normal physiology and in various disease states. Genetic variants in the human gene TRPM4 have been linked to several cardiac conduction disorders. TRPM4 has also been proposed to play a crucial role in secondary hemorrhage following spinal cord injuries. Spontaneously hypertensive rats with cardiac hypertrophy were shown to over-express the cardiac TRPM4 channel. Recent studies suggest that TRPM4 plays an important role in cardiovascular physiology and disease, even if most of the molecular and cellular mechanisms have yet to be elucidated. We conclude this review article with a brief overview of the compounds that have been shown to either inhibit or activate TRPM4 under experimental conditions. Based on recent findings, the TRPM4 channel can be proposed as a future target for the pharmacological treatment of cardiovascular disorders, such as hypertension and cardiac arrhythmias.

miR-199a-5p regulates urothelial permeability and may play a role in bladder pain syndrome

Defects in urothelial integrity resulting in leakage and activation of underlying sensory nerves are potential causative factors of bladder pain syndrome, a clinical syndrome of pelvic pain and urinary urgency/frequency in the absence of a specific cause. Herein, we identified the microRNA miR-199a-5p as an important regulator of intercellular junctions. On overexpression in urothelial cells, it impairs correct tight junction formation and leads to increased permeability. miR-199a-5p directly targets mRNAs encoding LIN7C, ARHGAP12, PALS1, RND1, and PVRL1 and attenuates their expression levels to a similar extent. Using laser microdissection, we showed that miR-199a-5p is predominantly expressed in bladder smooth muscle but that it is also detected in mature bladder urothelium and primary urothelial cultures. In the urothelium, its expression can be up-regulated after activation of cAMP signaling pathways. While validating miR-199a-5p targets, we delineated novel functions of LIN7C and ARHGAP12 in urothelial integrity and confirmed the essential role of PALS1 in establishing and maintaining urothelial polarity and junction assembly. The present results point to a possible link between miR-199a-5p expression and the control of urothelial permeability in bladder pain syndrome. Up-regulation of miR-199a-5p and concomitant down-regulation of its multiple targets might be detrimental to the establishment of a tight urothelial barrier, leading to chronic pain.

Pediatric severe asthma is characterized by eosinophilia and remodeling without T(H)2 cytokines

BACKGROUND: The pathology of pediatric severe therapy-resistant asthma (STRA) is little understood. OBJECTIVES: We hypothesized that STRA in children is characterized by airway eosinophilia and mast cell inflammation and is driven by the T(H)2 cytokines IL-4, IL-5, and IL-13. METHODS: Sixty-nine children (mean age, 11.8 years; interquartile range, 5.6-17.3 years; patients with STRA, n = 53; control subjects, n = 16) underwent fiberoptic bronchoscopy, bronchoalveolar lavage (BAL), and endobronchial biopsy. Airway inflammation, remodeling, and BAL fluid and biopsy specimen T(H)2 cytokines were quantified. Children with STRA also underwent symptom assessment (Asthma Control Test), spirometry, exhaled nitric oxide and induced sputum evaluation. RESULTS: Children with STRA had significantly increased BAL fluid and biopsy specimen eosinophil counts compared with those found in control subjects (BAL fluid, P < .001; biopsy specimen, P < .01); within the STRA group, there was marked between-patient variability in eosinophilia. Submucosal mast cell, neutrophil, and lymphocyte counts were similar in both groups. Reticular basement membrane thickness and airway smooth muscle were increased in patients with STRA compared with those found in control subjects (P < .0001 and P < .001, respectively). There was no increase in BAL fluid IL-4, IL-5, or IL-13 levels in patients with STRA compared with control subjects, and these cytokines were rarely detected in induced sputum. Biopsy IL-5(+) and IL-13(+) cell counts were also not higher in patients with STRA compared with those seen in control subjects. The subgroup (n = 15) of children with STRA with detectable BAL fluid T(H)2 cytokines had significantly lower lung function than those with undetectable BAL fluid T(H)2 cytokines. CONCLUSIONS: STRA in children was characterized by remodeling and variable airway eosinophil counts. However, unlike in adults, there was no neutrophilia, and despite the wide range in eosinophil counts, the T(H)2 mediators that are thought to drive allergic asthma were mostly absent.