Peptide-specific CTL induction in HBV-seropositive PBMC by stimulation with peptides in vitro: novel epitopes identified from chronic carriers

Cytotoxic T lymphocytes (CTL) recognize and destroy virus-infected cells, and it has been established that epitope-based peptides could induce such CTL in vivo as well as in vitro. In this study attempts were made to define the epitopes that are recognized by the CTL, and thus a series of 9- to 10-mer peptides derived from the amino acid sequences of hepatitis B virus (HBV) proteins were synthesized on the basis of the previously described HLA-A2 peptide binding motif. The binding assay of the synthetic peptides using transporter-associated with antigen processing (TAP)-deficient human cell line, T2, showed that eight out of 11 peptides tested enhanced the expression of HLA-A2 molecules on the T2 cell surface. Some of these peptides triggered activation of CTL in peripheral blood mononuclear cells of HBV-seropositive chronic carriers. The activated CTL in turn recognized and killed the T2 cells pulsed with the same peptides. This study shows that novel HLA-A2-restricted epitopes exist in the natural repertoire of immunity against HBV. These findings can be useful in developing peptide-based therapeutics against viral infections.     

The development of eosinophilic colitis after liver transplantation in children

Tacrolimus-based immunosuppression in pediatric liver transplant recipients is known to be associated with EGID. Our goal was to determine the incidence, risk factors, and characteristics of EGID in our pediatric liver transplantation program. This study was a retrospective analysis of 38 pediatric liver transplant recipients. Rectal mucosal biopsy was performed to evaluate for gastrointestinal PTLD and eosinophilic colitis. There were 14 patients (37%) who were diagnosed with eosinophilic colitis. The mean age at transplantation was 10.8 +/- 1.8 months. Those with eosinophilic colitis had a higher incidence of peripheral eosinophilia (p = 0.003) during the first two months following transplantation and had a higher EBV infection rate. Symptoms, such as diarrhea, hematochezia, and abdominal pain, became apparent after an average of three months; diagnoses were made at 6.9 +/- 2.0 months after transplantation. There were eight patients (57%) with elevated food-specific IgE levels. With food restriction treatment, the symptoms of patients improved. EGID should be considered when clinical symptoms are present, because symptoms of this disorder are similar to those of gastrointestinal PTLD. It should also be considered when peripheral eosinophila is detected or when EBV seroconversion develops during the first two months following transplantation.     

Dual Roles of CD40 on Microbial Containment and the Development of Immunopathology in Response to Persistent Fungal Infection in the Lung

Persistent pulmonary infection with Cryptococcus neoformans in C57BL/6 mice results in chronic inflammation that is characterized by an injurious Th2 immune response. In this study, we performed a comparative analysis of cryptococcal infection in wild-type versus CD40-deficient mice (in a C57BL/6 genetic background) to define two important roles of CD40 in the modulation of fungal clearance as well as Th2-mediated immunopathology. First, CD40 promoted microanatomic containment of the organism within the lung tissue. This protective effect was associated with: i) a late reduction in fungal burden within the lung; ii) a late accumulation of lung leukocytes, including macrophages, CD4⁺ T cells, and CD8+ T cells; iii) both early and late production of tumor necrosis factor-α and interferon-γ by lung leukocytes; and iv) early IFN-γ production at the site of T cell priming in the regional lymph nodes. In the absence of CD40, systemic cryptococcal dissemination was increased, and mice died of central nervous system infection. Second, CD40 promoted pathological changes in the airways, including intraluminal mucus production and subepithelial collagen deposition, but did not alter eosinophil recruitment or the alternative activation of lung macrophages. Collectively, these results demonstrate that CD40 helps limit progressive cryptococcal growth in the lung and protects against lethal central nervous system dissemination. CD40 also promotes some, but not all, elements of Th2-mediated immunopathology in response to persistent fungal infection in the lung.CD40, a 48-kDa type I transmembrane protein and member of the tumor necrosis factor receptor family, is a well-described costimulatory molecule expressed on B cells, dendritic cells (DC), macrophages, basophils, and platelets as well as nonhematopoietic cells including fibroblasts, epithelial, and endothelial cells. The ligand for CD40, known as CD154 or CD40L, is a type II transmembrane protein member of the tumor necrosis factor (TNF) superfamily expressed primarily by activated T cells, B cells, and platelets.^1,2,3 CD40 can be induced on DC, monocytes, and macrophages under inflammatory conditions.^4,5 Signaling via the CD40/CD40L pathway exerts numerous biological effects including: i) increased cytokine expression (especially TNF-α and Th1 cytokines interleukin (IL)-12 and interferon (IFN)-α) and nitric oxide production; ii) upregulation of additional costimulatory molecules (CD80 and CD86) on antigen-presenting cells (APC); iii) enhanced cell survival (particularly of B and T cells, DC, and endothelial cells); iv) Ig isotype switching; and v) somatic hypermutation of Ig.^1,4,5The CD40/CD40L signaling pathway contributes to adaptive Th1 immune responses required to clear Leishmanisa spp.,^6,7,8 Trypanosoma spp.,^6,7,8,9 Shistosoma mansoini,¹⁰ and the fungi Candida albicans¹¹ and Pneumocystis spp.¹² The enhanced production of IFN-γ, TNF-α, and nitric oxide associated with CD40/CD40L signaling is thought to be responsible for this protective effect. However, other studies have suggest that CD40/CD40L signaling is not required for successful host defense against Listeria monocytogenes,^13,14 Toxoplasma gondi,¹⁵ lymphocytic choriomeningitis virus,^16,17 or the fungus Hisoplasma capsulatum.^18,19 In models of Mycobacterium spp. infection, CD40 appears dispensable for clearance of an i.v. infection,^20,21 but essential for clearing the organism in response to aerosolized infection in the lungs.^22,23 Thus, the role of CD40 in antimicrobial host defense varies and depends not only on the specific pathogen but also on the primary site of infection.Cryptococcus neoformans, an opportunistic fungal pathogen acquired through inhalation, causes significant morbidity and mortality primarily in patients with AIDS, lymphoid or hematological malignancies, or patients receiving immunosuppressive therapy secondary to autoimmune disease or organ transplantation.^24,25 Infection in non-immunocompromised patients has been reported.^26,27,28 Murine models of cryptococcal infection in CBA/J or BALB/c mice demonstrate that development of a Th1 antigen-specific immune response characterized by IFN-γ production and classical activation of macrophages is required to eradicate the organism.^{29,30,31,32,33,34,35,36,37,38,39,40} In contrast, a model of persistent cryptococcal infection has been developed using C57BL/6 mice;^{41,42,43,44,45,46,47} this model reflects many features observed in humans diagnosed with allergic bronchopulmonary mycosis.⁴⁸ Specifically, these mice fail to clear the organism from the lung and develop characteristic Th2-mediated immunopathology including: i) tissue eosinophilia; ii) airway hyperreactivity, mucus production, and fibrosis; and iii) alternative macrophage activation associated with YM1 crystal deposition.The molecular mechanisms responsible for the immunopathologic response associated with persistent cryptococcal infection are not clearly defined. These features are abrogated in the absence of IL-4,⁴⁵ whereas more severe Th2-mediated lung injury occurs in the absence of IFN-γ.^29,41 TNF-α exerts a protective effect by enhancing IFN- γ production and the subsequent classical activation of lung macrophages.^31,35,49,50 Lymphocytes are critical mediators of this Th2 response as the pathological features of chronic cryptococcal infection are substantially diminished in CD4 T cell-depleted mice despite no change in fungal clearance.⁴²Although interactions between CD4 T cells and APC are critical determinants of T cell polarization in response to cryptococcal lung infection,^{49,51,52,53,54,55} the contribution of specific costimulatory molecules including the CD40/CD40L signaling pathway has not been fully elucidated. In vitro studies suggest that activation of the CD40/CD40L pathway in response to Cryptococcus promotes IFN-γ production by T cells and TNF-α, and nitric oxide (NO) production by monocytes.⁵⁶ In the absence of CD40L, primary pulmonary infection with a weakly virulent strain of C. neoformans was associated with impaired fungal clearance; however, measurements of immune function at the site of infection in the lung or evidence of systemic fungal dissemination were not evaluated.⁵⁷ The potential to target CD40 therapeutically is highlighted by studies showing that treatment of mice with disseminated or intracerebral cryptococcal infection with an agonist antibody to CD40 in combination with IL-2 improves survival.^58,59 In this study, we used gene-targeted CD40-deficient mice (on a C57BL/6 genetic background), a clinically relevant model, and assessments of immune function and histopathology in the lung to identify two unique roles for the CD40-signaling pathway in response to persistent cryptococcal lung infection.     

Efficacy of two triple eradication regimens in children with Helicobacter pylori infection

Triple therapy with bismuth subsalicylate, amoxicillin, metronidazole (BAM) or with omeprazole, amoxicillin, clarithromycin (OAC) has been commonly used for the eradication of Helicobacter pylori infection. We compared the efficacy of these triple therapies in children with H. pylori infection. We retrospectively analyzed results in 233 children with H. pylori infection and treated with OAC (n=141) or BAM (n=92). Overall eradication rates of triple therapy with OAC and BAM were 74% and 85%, respectively, which showed no statistical difference. Our study showed that the triple therapy with BAM was more effective for the first-line eradication of H. pylori infection in Korean children, but has no statistical difference with OAC regimen.     

Microcystic adenomas of the pancreas. Report of three cases with two of multicentric origin

Three cases of microcystic adenomas of the pancreas with special reference to multicentric origin are described. The gross features and light microscopic findings were consistent with those described as being microcystic adenomas, but in two cases the gross examination and gelatin-embedded giant slices revealed multiple, isolated development of tumors ranging from submacroscopic nodules to tumors 4.5 cm in diameter. The larger tumors often showed ragged margins with small satellite nodules around the masses. A central fibrolamellar stellate core with centrifugally radiating septation was found in most of the tumor masses, even in the smaller ones. Ultrastructural and immunohistochemical findings revealed a single row of glycogen-rich epithelial cells, but participation of myoepithelial cells was not confirmed. Instead, vimentin-positive cells (pericytes) within the interstitial space incorporated closely with the basal lamina of the cyst wall. This study suggests that a small percentage of microcystic adenomas of the pancreas develop in multiple tumors, and some appear as a single tumor by their confluence.     

Global quantification of left ventricular myocardial perfusion at dynamic CT imaging: Prognostic value

Background

There is no published data on the prognostic value of global myocardial perfusion values at stress dynamic CT myocardial perfusion imaging (CTMPI).

Doubling time of thymic epithelial tumours on CT: correlation with histological subtype

Objectives

We retrospectively evaluated the doubling time (DT) of thymic epithelial tumours (TET) according to the histological subtype on CT.

Methods

From January 2005 to June 2016, we enrolled 53 patients who had pathologically confirmed TET and at least two CT scans. Tumour size was measured using a two-dimensional method, and the DT was calculated. DTs were compared among histological subtypes, and factors associated with rapid tumour growth (DT <180 days) were assessed.

Results

In 42 of the 53 patients (79.2%) the tumours showed interval growth (>2 mm) during follow-up. The median DT for all tumours was 400 days (range 48–1,964 days). There were no significant differences in DT in relation to histological subtype (p?=?0.177). When TETs were recategorized into three groups, i.e. low-risk thymomas (types A, AB, B1), high-risk thymomas (types B2, B3), and thymic carcinoma, DT was significantly different among the groups (median DT 436, 381 and 189 days, respectively; p?=?0.031). Histological subtype (type B3 and thymic carcinoma) was the single independent predictor of rapid tumour growth.

Conclusions

The majority of TETs grew during follow-up with variable and relatively slow growth rates. Histological features of aggressive behaviour significantly correlated with a decreased DT and rapid growth.

Key points

? The majority of thymic epithelial tumours grew during follow-up (79.2%, 42/53).? Doubling times of thymic epithelial tumours were highly variable (median 400 days).? Histological features of aggressive behaviour significantly correlated with a decreased doubling time.

     

Alterations in GluR2 AMPA receptor phosphorylation at serine 880 following group I metabotropic glutamate receptor stimulation in the rat dorsal striatum

Phosphorylation of ionotropic glutamate receptors in the brain plays a crucial role in the regulation of synaptic plasticity. In this study, we investigated the regulation of α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionic acid (AMPA) receptor phosphorylation by thestimulation of group I metabotropic glutamate receptors (mGluRs) in the dorsal striatum in vivo. The results showed that intrastriatal infusion of the group I mGluR agonist, (RS)‐3,5‐dihydroxyphenylglycine (DHPG, 250 nmol), enhanced the sensitivity of GluR2 subunit in its phosphorylation at serine 880 (S880) in the dorsal striatum. This enhancement of the sensitivity of GluR2‐S880 phosphorylation was reduced by blocking group I mGluRs and N‐methyl‐D‐aspartate (NMDA) receptors. Similar reduction of the enhancement was also induced by inhibiting phospholipase C (PLC), calcium/calmodulin‐dependent protein kinase (CaMK), c‐Jun N‐terminal kinase (JNK), and protein kinase C (PKC). Inhibition of protein phosphatase (PP) 1/2A and calcineurin (PP2B) alone enhanced GluR2‐S880 phosphorylation in the dorsal striatum, whereas inhibition of these phosphatases did not further enhance the S880 phosphorylation by DHPG stimulation. In addition, inhibition of PP1/2A or PP2B also enhanced the phosphorylation of CaMKII, JNK and PKC. These data suggest that the phosphorylation of AMPA receptor GluR2 subunit at S880 is subject to the upregulation by the stimulation of group I mGluRs. Interactions among glutamate receptors, protein kinases, and PPs participate in this upregulation. © 2009 Wiley‐Liss, Inc.     

Interleukin-8 and tumor necrosis factor-alpha are increased in minimal change disease but do not alter albumin permeability

AIMS: Minimal change disease (MCD) is the most common primary nephrotic syndrome in children. Some suggested that interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-alpha) are involved in the pathogenesis of MCD. This study was done to see changes of plasma and urinary IL-8, TNF-alpha, and their effects on determination of permeability of glomerular basement membrane (BM) contributed by heparan sulfate proteoglycan (HSPG). METHODS: Study patients consisted of 19 biopsy-proven MCD children aged 2-15 years old. Both plasma, urinary IL-8 and TNF-alpha were measured. Employing the Millicell system, IL-8 and TNF-alpha were screened for the permeability factors. We examined whether IL-8 and TNF-alpha regulated BM HSPG gene expression and HS synthesis in the glomerular epithelial cells (GECs). RESULTS: Urinary IL-8 during relapse was significantly increased when compared with that of during remission or controls (13,996 +/- 2,811 vs. 2,941 +/- 373, 5,331 +/- 640 ng/mg.cr) (p < 0.05). Urinary TNF-alpha during relapse was also significantly increased (364.4 +/- 51.2 vs. 155.3 +/- 20.8, 36.0 +/- 4.5 ng/mg.cr) (p < 0.05). Plasma IL-8 during relapse was significantly increased compared to that during remission(1.19 +/- 0.62 vs. 0.51 +/- 0.42 ng/ml) (p < 0.05). However, the negative results were obtained in the permeability assay using the Millicell system. No difference was seen in BM HSPG gene expression and HS synthesis in the GECs. CONCLUSION: Therefore, it seems that both IL-8 and TNF-alpha may not play a disease-specific role in the pathogenesis of MCD.