Sessile Serrated Lesion of the Appendix in a Teenage Girl.

According to the literature, serrated lesions and polyps of the appendix are extremely rare in children or teenagers. Herein, we present the pathologic and molecular features of a sessile serrated lesion (SSL) that was incidentally found in the appendix of a teenage girl. Our findings not only illustrate that appendiceal SSL may occur in young patients such as teenagers but also confirm further that BRAF V600E mutation may be found in a subset of these neoplastic lesions.

A Trypanosoma brucei kinesin heavy chain promotes parasite growth by triggering host arginase activity.

BACKGROUND: In order to promote infection, the blood-borne parasite Trypanosoma brucei releases factors that upregulate arginase expression and activity in myeloid cells. METHODOLOGY/PRINCIPAL FINDINGS: By screening a cDNA library of T. brucei with an antibody neutralizing the arginase-inducing activity of parasite released factors, we identified a Kinesin Heavy Chain isoform, termed TbKHC1, as responsible for this effect. Following interaction with mouse myeloid cells, natural or recombinant TbKHC1 triggered SIGN-R1 receptor-dependent induction of IL-10 production, resulting in arginase-1 activation concomitant with reduction of nitric oxide (NO) synthase activity. This TbKHC1 activity was IL-4Rα-independent and did not mirror M2 activation of myeloid cells. As compared to wild-type T. brucei, infection by TbKHC1 KO parasites was characterized by strongly reduced parasitaemia and prolonged host survival time. By treating infected mice with ornithine or with NO synthase inhibitor, we observed that during the first wave of parasitaemia the parasite growth-promoting effect of TbKHC1-mediated arginase activation resulted more from increased polyamine production than from reduction of NO synthesis. In late stage infection, TbKHC1-mediated reduction of NO synthesis appeared to contribute to liver damage linked to shortening of host survival time. CONCLUSION: A kinesin heavy chain released by T. brucei induces IL-10 and arginase-1 through SIGN-R1 signaling in myeloid cells, which promotes early trypanosome growth and favors parasite settlement in the host. Moreover, in the late stage of infection, the inhibition of NO synthesis by TbKHC1 contributes to liver pathogenicity.

IL-10 limits production of pathogenic TNF by M1 myeloid cells through induction of nuclear NF-κB p50 member in Trypanosoma congolense infection-resistant C57BL/6 mice.

A balance between parasite elimination and control of infection-associated pathogenicity is crucial for resistance to African trypanosomiasis. By producing TNF and NO, CD11b(+) myeloid cells with a classical activation status (M1) contribute to parasitemia control in experimental Trypanosoma congolense infection in resistant C57BL/6 mice. However, in these mice, IL-10 is required to regulate M1-associated inflammation, avoiding tissue/liver damage and ensuring prolonged survival. In an effort to dissect the mechanisms behind the anti-inflammatory activity of IL-10 in T. congolense-infected C57BL/6 mice, we show, using an antibody blocking the IL-10 receptor, that IL-10 impairs the accumulation and M1 activation of TNF/iNOS-producing CD11b(+) Ly6C(+) cells in the liver. Using infected IL-10(flox/flox) LysM-Cre(+/+) mice, we show that myeloid cell-derived IL-10 limits M1 activation of CD11b(+) Ly6C(+) cells specifically at the level of TNF production. Moreover, higher production of TNF in infected IL-10(flox/flox) LysM-Cre(+/+) mice is associated with reduced nuclear accumulation of the NF-κB p50 subunit in CD11b(+) M1 cells. Furthermore, in infected p50(-/-) mice, TNF production by CD11b(+) Ly6C(+) cells and liver injury increases. These data suggest that preferential nuclear accumulation of p50 represents an IL-10-dependent anti-inflammatory mechanism in M1-type CD11b(+) myeloid cells that regulates the production of pathogenic TNF during T. congolense infection in resistant C57BL/6 mice.

Tip-DC development during parasitic infection is regulated by IL-10 and requires CCL2/CCR2, IFN-gamma and MyD88 signaling.

The development of classically activated monocytic cells (M1) is a prerequisite for effective elimination of parasites, including African trypanosomes. However, persistent activation of M1 that produce pathogenic molecules such as TNF and NO contributes to the development of trypanosome infection-associated tissue injury including liver cell necrosis in experimental mouse models. Aiming to identify mechanisms involved in regulation of M1 activity, we have recently documented that during Trypanosoma brucei infection, CD11b(+)Ly6C(+)CD11c(+) TNF and iNOS producing DCs (Tip-DCs) represent the major pathogenic M1 liver subpopulation. By using gene expression analyses, KO mice and cytokine neutralizing antibodies, we show here that the conversion of CD11b(+)Ly6C(+) monocytic cells to pathogenic Tip-DCs in the liver of T. brucei infected mice consists of a three-step process including (i) a CCR2-dependent but CCR5- and Mif-independent step crucial for emigration of CD11b(+)Ly6C(+) monocytic cells from the bone marrow but dispensable for their blood to liver migration; (ii) a differentiation step of liver CD11b(+)Ly6C(+) monocytic cells to immature inflammatory DCs (CD11c(+) but CD80/CD86/MHC-II(low)) which is IFN-gamma and MyD88 signaling independent; and (iii) a maturation step of inflammatory DCs to functional (CD80/CD86/MHC-II(high)) TNF and NO producing Tip-DCs which is IFN-gamma and MyD88 signaling dependent. Moreover, IL-10 could limit CCR2-mediated egression of CD11b(+)Ly6C(+) monocytic cells from the bone marrow by limiting Ccl2 expression by liver monocytic cells, as well as their differentiation and maturation to Tip-DCs in the liver, showing that IL-10 works at multiple levels to dampen Tip-DC mediated pathogenicity during T. brucei infection. A wide spectrum of liver diseases associates with alteration of monocyte recruitment, phenotype or function, which could be modulated by IL-10. Therefore, investigating the contribution of recruited monocytes to African trypanosome induced liver injury could potentially identify new targets to treat hepatic inflammation in general, and during parasite infection in particular.

Fibrin-Associated EBV-Positive Large B-Cell Lymphoma Incidentally Found Within a Multinodular Goiter.

Fibrin-associated diffuse large B-cell lymphoma (fibrin-associated DLBCL) is a very rare subtype of Epstein-Barr virus (EBV)-associated DLBCL that usually develops within fibrin-rich lesions such as cardiac myxoma, chronic hematoma, thrombus, pseudocysts or cysts, prosthetic devices or breast implants. The pathogenesis as well as the clinicopathologic features of this usually indolent lymphoproliferative disorder, which are based on the analysis of a relatively limited number of cases, are still poorly known. Herein, we report a case of fibrin-associated DLBCL that was incidentally found within a multinodular goiter, a location not yet reported to our knowledge. Our findings not only illustrate further the specific nature of this peculiar lymphoproliferative disorder but also allow some interesting comments on its pathogenesis.

IL-10 dampens TNF/inducible nitric oxide synthase-producing dendritic cell-mediated pathogenicity during parasitic infection.

Antiparasite responses are associated with the recruitment of monocytes that differentiate to macrophages and dendritic cells at the site of infection. Although classically activated monocytic cells are assumed to be the major source of TNF and NO during Trypanosoma brucei brucei infection, their cellular origin remains unclear. In this study, we show that bone marrow-derived monocytes accumulate and differentiate to TNF/inducible NO synthase-producing dendritic cells (TIP-DCs) in the spleen, liver, and lymph nodes of T. brucei brucei-infected mice. Although TIP-DCs have been shown to play a beneficial role in the elimination of several intracellular pathogens, we report that TIP-DCs, as a major source of TNF and NO in inflamed organs, could contribute actively to tissue damage during the chronic stage of T. brucei brucei infection. In addition, the absence of IL-10 leads to enhanced differentiation of monocytes to TIP-DCs, resulting in exacerbated pathogenicity and early death of the host. Finally, we demonstrate that sustained production of IL-10 following IL-10 gene delivery treatment with an adeno-associated viral vector to chronically infected mice limits the differentiation of monocytes to TIP-DCs and protects the host from tissue damage.

Internalization of EGF receptor following lipid rafts disruption in keratinocytes is delayed and dependent on p38 MAPK activation.

The receptor for epidermal growth factor (EGF) plays an important role in epidermal keratinocytes and is known to move out of lipid raft after cholesterol depletion, leading to ligand-independent activation. Accumulation of evidence indicates the ability of EGF receptor (EGFR) to undergo internalization without participation of the ligand under the control of p38 MAPK during stress conditions. Since cholesterol depletion using methyl-beta-cyclodextrin is known to induce ligand-independent activation of EGFR in keratinocytes, we investigated by confocal microscopy and ligand-binding tests the processing and localization of EGFR following lipid raft disruption. Here, we report the dimerization and the slow internalization of the receptor accompanied by the delayed phosphorylation of tyrosine 1068 and its degradation by the proteasome. We also demonstrate the involvement of p38 MAPK during the process of internalization, which can be considered as a protective response to stress. Moreover, cholesterol-depleted keratinocytes recover their ability to proliferate during the recovery period that follows lipid raft disruption.

Primary breast amyloidosis presenting solely as nonpalpable microcalcifications: a case report with review of the literature.

Primary breast amyloidosis is a rare disease and usually occurs as unilateral or bilateral palpable masses. Primary breast amyloidosis presenting solely as microcalcifications is extremely rare. The authors report a case of a 73-year-old woman with persistent suspicious microcalcifications without palpable mass. The diagnosis was established by the presence of an amorphous and eosinophilic material that was positive for Congo red and dichroic under polarized light. Paraffin immunohistochemistry revealed the presence of kappa light chains (AL-type amyloidosis). The amyloid deposits were associated with microcalcifications. A complete work up was performed to exclude other localisations or associated pathologies and was negative. The primary breast amyloidosis is discussed and a review of the literature is presented.

Evaluation of a low density DNA microarray for small B-cell non-Hodgkin lymphoma differential diagnosis.

Lymphomas are classified according to the World Health Organisation (WHO) classification which defines subtypes on the basis of clinical, morphological, immunophenotypic, molecular and cytogenetic criteria. Differential diagnosis of the subtypes is sometimes difficult, especially for small B-cell lymphoma (SBCL). Standardisation of molecular genetic assays using multiple gene expression analysis by microarrays could be a useful complement to the current diagnosis. The aim of the present study was to develop a low density DNA microarray for the analysis of 107 genes associated with B-cell non-Hodgkin lymphoma and to evaluate its performance in the diagnosis of SBCL. A predictive tool based on Fisher discriminant analysis using a training set of 40 patients including four different subtypes (follicular lymphoma n = 15, mantle cell lymphoma n = 7, B-cell chronic lymphocytic leukemia n = 6 and splenic marginal zone lymphoma n = 12) was designed. A short additional preliminary analysis to gauge the accuracy of this signature was then performed on an external set of nine patients. Using this model, eight of nine of those samples were classified successfully. This pilot study demonstrates that such a microarray tool may be a promising diagnostic approach for small B-cell non-Hodgkin lymphoma.

Heparin-binding EGF-like growth factor is induced by disruption of lipid rafts and oxidative stress in keratinocytes and participates in the epidermal response to cutaneous wounds.

Epidermal homeostasis and repair of the skin barrier require that epidermal keratinocytes respond to alterations of their environment. We report that cellular stress with methyl-beta-cyclodextrin (MBCD), a molecule that extracts membrane cholesterol and thereby disrupts the structure of lipid rafts, strongly induces the synthesis of heparin-binding EGF-like growth factor (HB-EGF) in keratinocytes through the activation of p38 mitogen-activated protein kinase. Interesting parallels between lipid raft disruption and oxidative stress can be drawn as hydrogen peroxide induces p38 activation and HB-EGF synthesis in keratinocytes. Consistent with other studies, we show increased HB-EGF expression in keratinocytes located at the margin of wounded skin areas. Analyzing cultured keratinocytes exposed to rhHB-EGF, we report increased HB-EGF mRNA levels and alterations in the expression of differentiation markers. Interestingly, identical alterations in differentiation markers are shown to occur in vivo at the wound margin and in HB-EGF-treated cultures. In addition, in vitro sectioning of skin samples also induces the expression of HB-EGF at the border of the incisions. Altogether, our data suggest that expression of HB-EGF is a marker of the keratinocyte's response to a challenging environment and demonstrate that this growth factor alters the phenotype of keratinocytes in a manner similar to that observed during epidermal repair.

Experimental expansion of the regulatory T cell population increases resistance to African trypanosomiasis.

Inflammatory responses mounted to eliminate parasites can be lethal if not counterbalanced by regulatory responses protecting the host from collateral tissue damage. Here, we show that the maintained inflammation associated with tissue damage, anemia, and reduced survival of Trypanosoma brucei-infected mice correlates with the absence of the expansion of the regulatory T (T(reg)) cell population. Induction of T(reg) cell expansion via CD28 superagonist antibody treatment in these mice down-regulated interferon-gamma production by T cells and tumor necrosis factor-alpha and reactive oxygen species production by classically activated macrophages, triggered the development of alternatively activated macrophages, delayed the onset of liver injury, diminished the anemia burden, and prolonged the survival of infected animals. Thus, triggering the expansion of the T(reg) cell population coupled with the induction of alternatively activated macrophages can restore the balance between pro- and anti-inflammatory signals and thereby limit the pathogenicity of African trypanosomiasis.

Alternatively activated myeloid cells limit pathogenicity associated with African trypanosomiasis through the IL-10 inducible gene selenoprotein P.

Uncontrolled inflammation is a major cause of tissue injury/pathogenicity often resulting in death of a host infected with African trypanosomes. Thus, comparing the immune response in hosts that develop different degrees of disease severity represents a promising approach to discover processes contributing to trypanosomiasis control. It is known that limitation of pathogenicity requires a transition in the course of infection, from an IFN-gamma-dependent response resulting in the development of classically activated myeloid cells (M1), to a counterbalancing IL-10-dependent response associated with alternatively activated myeloid cells (M2). Herein, mechanisms and downstream effectors by which M2 contribute to lower the pathogenicity and the associated susceptibility to African trypanosomiasis have been explored. Gene expression analysis in IL-10 knockout and wild-type mice, that are susceptible and relatively resistant to Trypanosoma congolense infection, respectively, revealed a number of IL-10-inducible genes expressed by M2, including Sepp1 coding for selenoprotein P. Functional analyses confirm that selenoprotein P contributes to limit disease severity through anti-oxidant activity. Indeed, Sepp1 knockout mice, but not Sepp1(Delta)(240-361) mice retaining the anti-oxidant motif but lacking the selenium transporter domain of selenoprotein P, exhibited increased tissue injury that associated with increased production of reactive oxygen species and increased apoptosis in the liver immune cells, reduced parasite clearance capacity of myeloid cells, and decreased survival. These data validate M2-associated molecules as functioning in reducing the impact of parasite infection on the host.

African trypanosomiasis: naturally occurring regulatory T cells favor trypanotolerance by limiting pathology associated with sustained type 1 inflammation.

Tolerance to African trypanosomes requires the production of IFN-gamma in the early stage of infection that triggers the development of classically activated macrophages controlling parasite growth. However, once the first peak of parasitemia has been controlled, down-regulation of the type 1 immune response has been described. In this study, we have evaluated whether regulatory T cells (Tregs) contribute to the limitation of the immune response occurring during Trypanosoma congolense infection and hereby influence the outcome of the disease in trypanotolerant C57BL/6 host. Our data show that Foxp3+ Tregs originating from the naturally occurring Treg pool expanded in the spleen and the liver of infected mice. These cells produced IL-10 and limited the production of IFN-gamma by CD4+ and CD8+ effector T cells. Tregs also down-regulated classical activation of macrophages resulting in reduced TNF-alpha production. The Treg-mediated suppression of the type 1 inflammatory immune response did not hamper parasite clearance, but was beneficial for the host survival by limiting the tissue damages, including liver injury. Collectively, these data suggest a cardinal role for naturally occurring Tregs in the development of a trypanotolerant phenotype during African trypanosomiasis.

Oxidative stress, KLF6 and transforming growth factor-beta up-regulation differentiate non-alcoholic steatohepatitis progressing to fibrosis from uncomplicated steatosis in rats.

BACKGROUND/AIMS: Pathogenesis of non-alcoholic steatohepatitis (NASH) remains poorly understood. Cytochrome P450 2E1 (CYP 2E1), cytokines, oxidative stress and activation of hepatic stellate cells seem to play a role in this process. The aim was to determine the potential implication of these factors in the progression from uncomplicated steatosis to steatohepatitis with progressive fibrosis. METHODS: Animals were fed a standard diet, a 5% orotic acid-diet (OA) developing hepatic steatosis, or the methionine-choline deficient (MCD) diet inducing steatohepatitis for 2 and 6 weeks. Lipid peroxidation, CYP 2E1 expression and activity, expression of UCP-2, interleukin (IL)-6, transforming growth factor (TGF)beta1, KLF6 mRNAs, and activation of hepatic stellate cells were examined by gas chromatography, high-performance liquid chromatography, Western blotting, quantitative polymerase chain reaction and immunohistochemistry. RESULTS: Lipid peroxidation increased in the MCD model whereas only minor changes occurred in the OA model. KLF6 and TGFbeta1 mRNAs were selectively up-regulated in MCD animals. Stellate cell activation, inflammation and collagen deposition only occurred in the MCD group. CYP 2E1 expression and activity increased in the OA group while both decreased in MCD animals. UCP-2 and IL-6 mRNA increased in both groups. CONCLUSIONS: In the context of steatosis, lipid peroxidation is associated with inflammation and stellate cell activation with concomitant increase in TGFbeta1 production, possibly through up-regulation of KLF6.