Miao-Tzu Huang

Increased transforming growth factor-beta (TGF-β)-secreting T cells and IgA anti-cardiolipin antibody levels during acute stage of childhood Henoch–Schönlein purpura

Henoch–Schönlein purpura (HSP) is a small vessel vasculitis characterized by increased serum IgA and IgA‐dominant immune complex deposition in lesions. The involvement of IgA implies a probable role for TGF‐β, a major factor in IgA production, in the pathogenesis of HSP. Among IgA antibodies, serum IgA anti‐cardiolipin antibodies (aCL) have been found in many diseases, including vasculitis. In addition to the clinical presentations and laboratory parameters, we further investigated the roles of IgA aCL and TGF‐β in childhood HSP. Twenty‐six Chinese children with the diagnosis of HSP were enrolled. Blood samples from these patients were collected at both acute and convalescent stages. Intracellular staining of lymphocytes was performed to enumerate type 1 (interferon‐gamma‐secreting), type 2 (IL‐4‐secreting), and type 3 (TGF‐β‐secreting) helper T cells. Serum levels of TGF‐β were detected by ELISA. Serum IgA aCL of 21 of 26 patients at the acute stage, 11 of them at the convalescent stage, were measured by ELISA. The data showed that IgA aCL serum levels were significantly elevated in patients compared with healthy controls (P < 0·001), and those patients at the convalescent stage (P < 0·001). In addition, TGF‐β‐secreting T cells were significantly elevated during the acute stage, and decreased at the convalescent stage. Although more studies are needed, the high prevalence of IgA aCL and increased TGF‐β‐secreting T cells in children with acute HSP revealed some points which should permit a better understanding of the pathogenesis of HSP.

Regulatory T cells negatively regulate neovasculature of airway remodeling via DLL4-Notch signaling.

Regulatory T cells (Treg) have been shown to prevent the development of allergic asthma; however, the role of Treg in asthma with established airway remodeling is unknown. To address this, we exploited an OVA-induced chronic asthma mouse model wherein Treg were adoptively transferred to the mice at chronic stage of the model. We found that among the structural alterations of airway remodeling, Treg selectively reduced the vessel numbers in both peritracheal and peribronchial regions and the lung parenchyma. Extracellular matrix deposition, mucus metaplasia, muscular hyperplasia, and vasodilation, as were also induced by chronic allergen challenge, were not affected by Treg. TUNEL staining of the lung sections revealed an increased endothelial cell (EC) apoptosis in mice receiving Treg transfers compared with their asthmatic counterparts. By using Matrigel angiogenesis assays, we showed that Treg inhibited EC angiogenesis both in vitro and in vivo. Treg preferentially expressed Notch ligand DLL4, and an anti-DLL4 blocking Ab abrogated the inhibitory effect of Treg on EC tube formation. In vivo, decreased airway and lung vessel numbers as well as ameliorated airway hyperresponsiveness after Treg transfers were reverted when Treg-derived DLL4 signal was blocked by the anti-DLL4 Ab. Our findings demonstrate a novel function of Treg whereby Treg down-regulate remodeling angiogenesis via proapoptotic DLL4-Notch signaling, and suggest a therapeutic potential of Treg in alleviating airway hyperresponsiveness of chronic asthma.

β2-agonist exerts differential effects on the development of cord blood T cells but not on peripheral blood T cells

Asthma is a chronic inflammatory disease characterized by reversible airway obstruction caused by edematous airway lining, thickened mucosal secretions, and smooth muscle constriction. β2‐adrenoceptor agonists are widely used in the treatment of bronchial asthma because of their ability to induce relaxation of airway smooth muscle. Evidence indicates that desensitization and down‐regulation of β‐adrenoceptors occurs in long‐term β2‐agonist therapy, and these medications were thought to cause increased severity of, and mortality in, asthma. The purpose of this study was to delineate further the potential adverse effects of β2‐agonists on the development of T lymphocytes. T cells isolated from umbilical cord blood and adult peripheral blood were cultured in the presence of salbutamol. Intracellular staining with fluorescence‐labeled antibodies was used to differentiate the frequency of type 1 T‐helper (Th1) and type 2 T‐helper (Th2) cells. The results showed a statistically significant inverse relationship between the concentration of salbutamol and the ratio of Th1 over Th2 on cord blood T cells. However, this trend was not observed in adult peripheral blood T cells. The data revealed another potential adverse effect in which chronic β2‐agonist exposure predisposed differentiation of T lymphocytes towards Th2 while that of Th1 was relatively suppressed, especially in cord blood T cells. Hence, β2‐agonists, despite their effect in symptomatic rescue in asthma, should not be used indiscriminately as long‐term therapeutic agents.

Autoimmune Manifestations in Patients with Primary Immunodeficiency

Primary immunodeficiency comprises a heterogeneous group of disorders. Autoimmune and/or rheumatic manifestations are not uncommon in these patients. It may be the first and/or sole sign before the underlying disease is established. This study focuses on the children of primary immunodeficiency with autoimmune disease to survey the clinical and laboratory finding retrospectively. From January 1985 to June 1998, ten patients (M:F = 9:1) of primary immunodeficiency with at least one well defined autoimmune disease were identified. The underlying immunodeficiency included three with Brutons disease, three with common variable immunodeficiency, one with hyper-IgM, one with primary CD4 T-cell deficiency and two with Wiskott-Aldrich syndrome. The autoimmune manifestations include arthritis in six, ulcerative colitis in one, and autoimmune hemolytic anemia in three children. The major treatment was steroid and non-steroid anti-inflammatory drug. Infection could be controlled with antibiotics and intravenous immunoglobulin in all save one. The morbidity among these patients included bronchiectasis with pulmonary hypertension in three, joint stiffness, short stature, and delayed puberty in two. In conclusion, autoimmune diseases are frequently seen in patients with primary immunodeficiency. It could be the first and/or sole sign of disease. The possibility of immunodeficiency should be kept in mind when evaluating patients with autoimmune diseases.

Prognostic Significance of TWEAK Expression in Colorectal Cancer and Effect of Its Inhibition on Invasion

BackgroundTumor necrosis factor-like weak inducer of apoptosis (TWEAK) has been implicated in tumor development and progression. The aim of this study was to investigate the role of TWEAK in colorectal cancer (CRC) progression.MethodsTo investigate the involvement of TWEAK in the progression of human CRC, normal, and tumor specimens from 174 patients were analyzed immunohistochemically for the expression of TWEAK. TWEAK recombinant protein treatment, transfection of expression plasmids, and small interfering RNA to knockdown TWEAK expression were performed to test invasive ability with a Boyden chamber. The mRNA expression profile in recombinant TWEAK treatment was compared to a control group by microarray analysis. To identify downstream effectors, Raf kinase inhibitor (RKIP) and its correlation with TWEAK in vitro and in vivo were examined by quantitative real-time polymerase chain reaction and invasion assays.ResultsCRC patients whose tumors displayed high TWEAK expression had a statistically significantly higher overall survival and a disease-free advantage over those with a low TWEAK expression. In in vitro invasion assays, alterations in TWEAK expression in CRC cell lines inversely modulated their invasive ability. By means of integrated genomics, we identified RKIP as a downstream effector in TWEAK-mediated invasion inhibition. Knockout of RKIP expression in HCT116 cells by short hairpin RNA (shRKIP) resulted in increased invasiveness. Clinically, RKIP and TWEAK mRNA expression showed strong positive correlations in CRC patient samples.ConclusionsOur results implicate TWEAK as a key regulator of CRC invasion, and it appears to be a useful prognostic factor for patients with CRC.

Hepatitis B virus surface antigen can activate dendritic cells and modulate T helper type immune response

Hepatitis B virus surface antigen (HBsAg) is a major antigen of hepatitis B virus (HBV). Dendritic cells (DC) of HBV carriers have been reported to exhibit functional impairment. In this study, the role of HBsAg on mice bone marrow‐derived dendritic cells and immune responses in vivo was studied. The immune modulatory function of HBsAg was explored by using mice bone marrow‐derived dendritic cells in vitro and also by examining an ovalbumin (OVA) specific immune response in vivo. Treatment of dendritic cells with HBsAg resulted in enhanced cell surface expression of cluster of differentiation (CD) 80, CD83, CD86, and major histocompatibility complex (MHC) class II, and enhanced production of interleukin (IL)‐12 p40 and IL‐12 p70. Treatment of dendritic cells with HBsAg resulted in decreased T cell secretion of IL‐5 by OVA stimulation. In addition, the results showed stronger OVA‐specific immunoglobulin (Ig) M and weaker IgG responses in mice sera when they had been immunized with OVA and co‐injected with HBsAg. It was also found that the mice exhibited significant enhancement of anti‐OVA IgG2a antibody (Ab), as well as marked inhibition of IgG1 Ab production. In cellular immune responses, IL‐5 production was significantly decreased and interferon (IFN)‐γ increased in the group co‐injected with HBsAg. On the other hand, the induction of lymphoproliferative response to OVA stimulation in spleen cells was decreased in the HBsAg co‐injected group. These results demonstrate that HBsAg can affect the differentiation of T helper (Th) cells, which might provide a strategy for improving its prophylactic and therapeutic efficacy.

Lymph node trafficking of regulatory T cells is prerequisite for immune suppression

Regulatory T cells have a crucial role in health and disease because of their immune regulation function. However, the anatomic sites where regulatory T cells exert optimal immune regulation are open to debate. In our current study with the use of a shear‐stress flow assay, we found that regulatory T cells exhibited significantly decreased adhesion to either activated endothelial monolayer or intercellular adhesion molecule 1 or E‐selectin‐coated surfaces compared with activated effector T cells. The less transmigration capacity of the regulatory T cells prompted our speculation of preferential lymph node localization for the regulatory T cells that endowed these cells with immune regulation function in the most efficient manner. To test this hypothesis, the role of lymph node localization in regulatory T cell–mediated immune suppression was evaluated with a footpad inflammation model. We found that adoptively transferred regulatory T cells inhibited the development of footpad inflammation. In addition, although blockage of CCR7 or CD62L had no effect on the immune suppressive function of the regulatory T cells per se, pretreatment of the regulatory T cells with either CCR7 or CD62L blocking antibodies prevented their recruitment into draining lymph nodes and concomitantly abrogated the immune suppressive effects of adoptively transferred regulatory T cells during footpad inflammation. Our data demonstrate the crucial role of lymph node localization in regulatory T cell–mediated immune suppression and suggest a probable hierarchy in the anatomic sites for optimal immune regulation. Elucidating the relationships between the transmigration characteristics of the regulatory T cells and their immune regulation function will provide insightful information for regulatory T cell–based cell therapy.

Feedback regulation of IFN-α/β signaling by Axl receptor tyrosine kinase modulates HBV immunity.

Hepatitis B virus (HBV) is known to cause age‐dependent infection outcomes wherein most infections during young age result in chronicity. The mechanism underlying the differential outcome remains elusive. By using hydrodynamic injection of the replication‐competent pAAV‐HBV, we established a mouse model in which HBV persistence was generated in 4–5 w/o C57BL/6 young mice, but not in adult mice over 10 w/o. HBV‐tolerant young mice expressed higher interferon (IFN)‐α/β levels in hepatocytes and intrahepatic plasmacytoid DCs (pDCs) than adult mice after pAAV‐HBV injection. Excessive IFN‐α/β expression in young mice was associated with induction of the Axl regulatory pathway and expansion of intrahepatic Treg cells. In line with these findings, augmented IFN‐β expression increased Axl expression in the liver and HBV persistence in adult mice, whereas IFN‐α/β signaling blockage decreased Axl expression and HBV persistence in young mice. Accordingly, Axl overexpression decreased HBV clearance of adult mice whereas Axl silencing enhanced HBV clearance of young mice. In vitro, IFN‐β priming of pDCs and Axl‐overexpressing macrophages enhanced Treg‐cell differentiation. These findings suggest that age‐dependent HBV chronicity is attributed to IFN‐β‐Axl immune regulation, which is selectively induced in young mice by excessive IFN‐α/β production at early stage of HBV infection.