Bartonella henselae Persistence within Mesenchymal Stromal Cells Enhances Endothelial Cell Activation and Infectibility That Amplifies the Angiogenic Process.

Some bacterial pathogens can manipulate the angiogenic response, suppressing or inducing it for their own ends. In humans, Bartonella henselae is associated with cat-scratch disease and vasculoproliferative disorders such as bacillary angiomatosis and bacillary peliosis. Although endothelial cells (ECs) support the pathogenesis of B. henselae, the mechanisms by which B. henselae induces EC activation are not completely clear, as well as the possible contributions of other cells recruited at the site of infection. Mesenchymal stromal cells (MSCs) are endowed with angiogenic potential and play a dual role in infections, exerting antimicrobial properties but also acting as a shelter for pathogens. Here, we delved into the role of MSCs as a reservoir of B. henselae and modulator of EC functions. B. henselae readily infected MSCs and survived in perinuclearly bound vacuoles for up to 8 days. Infection enhanced MSC proliferation and the expression of epidermal growth factor receptor (EGFR), Toll-like receptor 2 (TLR2), and nucleotide-binding oligomerization domain-containing protein 1 (NOD1), proteins that are involved in bacterial internalization and cytokine production. Secretome analysis revealed that infected MSCs secreted higher levels of the proangiogenic factors vascular endothelial growth factor (VEGF), fibroblast growth factor 7 (FGF-7), matrix metallopeptidase 9 (MMP-9), placental growth factor (PIGF), serpin E1, thrombospondin 1 (TSP-1), urokinase-type plasminogen activator (uPA), interleukin 6 (IL-6), platelet-derived growth factor D (PDGF-D), chemokine ligand 5 (CCL5), and C-X-C motif chemokine ligand 8 (CXCL8). Supernatants from B. henselae-infected MSCs increased the susceptibility of ECs to B. henselae infection and enhanced EC proliferation, invasion, and reorganization in tube-like structures. Altogether, these results indicate MSCs as a still underestimated niche for persistent B. henselae infection and reveal MSC-EC cross talk that may contribute to exacerbate bacterium-induced angiogenesis and granuloma formation.

Angiomiolipoma epitelioide hepático: correlación clínico-patológica en una serie de 4 casos / Epithelioid angiomyolipoma of the liver: clinicopathological correlation in a series of 4 cases

El angiomiolipoma hepático es una neoplasia rara que puede llegar a ser difícil de diagnosticar en casos de biopsia ecoguiada. Hemos estudiado 4 casos de pacientes de sexo femenino, con una media de edad de 51 años. Ninguno de los pacientes se ha presentado con síntomas abdominales específicos, ni otras masas tumorales detectadas incidentalmente. Uno de ellos tenía antecedentes personales relevantes: carcinoma de células renales. Este mismo paciente fue diagnosticado de un angiomiolipoma renal contralateral. Ninguno de los pacientes ha mostrado evidencia de padecer esclerosis tuberosa. Tres de los tumores han sido diagnosticados por biopsia y en sólo uno de los pacientes se ha decidido la extirpación quirúrgica completa del tumor. En ninguno de los pacientes se ha observado evidencia de recidiva de la enfermedad o aumento del tamaño tumoral durante un periodo medio de 45 meses. Histológicamente los tumores se han subclasificado en angiomiolipomas epitelioides. En el 50% de los casos se ha observado hematopoyesis extramedular. La primera impresión diagnóstica mediante métodos de imagen incluía: hiperplasia nodular focal, adenoma hepático, carcinoma hepatocelular y metástasis. Mediante técnicas de inmunohistoquímica se ha demostrado que todos los tumores expresaban marcadores melanocíticos (HMB45 y Melan A) y marcadores de células musculares lisas (actina de músculo liso). El diagnóstico de estos tumores está aumentando debido a los programas de detección precoz de carcinoma hepatocelular en pacientes con cirrosis. Hay que tener en cuenta su amplio espectro de diversidad morfológica para evitar el diagnóstico incorrecto de una neoplasia maligna (AU)

Hepatic angiomyolipoma is a rare neoplasm that can be difficult to diagnose in cases of ecoguide biopsy. We studied 4 cases of female patients with a mean age of 51 years. None of the patients presented specific abdominal symptoms, or other tumour masses detected by chance. One of them had relevant personal history: Renal cell carcinoma. This same patient was diagnosed with a contralateral renal angiomyolipoma. None of the patients showed evidence of tuberous sclerosis. Three tumours have been diagnosed by biopsy and only in one patient was decided to completely remove the tumour surgically. None of the patients had evidence of recurrence of disease or an increase in tumour size over an average period of 45 months. Histologically, the tumours have been sub classified into angiomyolipomas epithelioid. In 50% of the cases, extramedullary haematopoiesis was observed. The first diagnostic impression using imaging methods included: Focal nodular hyperplasia, hepatocellular adenoma, hepatocellular carcinoma and metastasis. By immunohistochemistry, it has been demonstrated that all tumours expressing melanocytic markers (HMB45 and Melan A) and markers of smooth muscle cells (smooth muscle actin). The diagnosis of these tumours is increasing due to programmes for early detection of hepatocellular carcinoma in patients with liver cirrhosis. It must be taken into account their broad spectrum of morphological diversity to avoid incorrect diagnosis of a malignant neoplasm (AU)

Infection of human brain vascular pericytes (HBVPs) by Bartonella henselae.

Angiogenesis is an important physiological and pathological process. Bartonella is the only genus of bacteria known to induce pathological angiogenesis in the mammalian host. Bartonella-induced angiogenesis leads to the formation of vascular tumors including verruga peruana and bacillary angiomatosis. The mechanism of Bartonella-induced angiogenesis is not completely understood. Pericytes, along with endothelial cells, play an important role in physiological angiogenesis, and their role in tumor angiogenesis has been extensively studied. Abnormal signaling between endothelial cells and pericytes contributes to tumor angiogenesis and metastasis; however, the role of pericytes in Bartonella-induced angiogenesis is not known. In this study, after infecting human brain vascular pericytes (HBVPs) with Bartonella henselae, we found that these bacteria were able to invade HBVPs and that bacterial infection resulted in decreased pericyte proliferation and increased pericyte production of vascular endothelial growth factor (VEGF) when compared to the uninfected control cells. In the context of pathological angiogenesis, reduced pericyte coverage, accompanied by increased VEGF production, may promote endothelial cell proliferation and the formation of new vessels.

Bartonella henselae engages inside-out and outside-in signaling by integrin ß1 and talin1 during invasome-mediated bacterial uptake.

The VirB/D4 type IV secretion system (T4SS) of the bacterial pathogen Bartonella henselae (Bhe) translocates seven effector proteins (BepA-BepG) into human cells that subvert host cellular functions. Two redundant pathways dependent on BepG or the combination of BepC and BepF trigger the formation of a bacterial uptake structure termed the invasome. Invasome formation is a multi-step process consisting of bacterial adherence, effector translocation, aggregation of bacteria on the cell surface and engulfment, and eventually, complete internalization of the bacterial aggregate occurs in an F-actin-dependent manner. In the present study, we show that Bhe-triggered invasome formation depends on integrin-ß1-mediated signaling cascades that enable assembly of the F-actin invasome structure. We demonstrate that Bhe interacts with integrin ß1 in a fibronectin- and VirB/D4 T4SS-independent manner and that activated integrin ß1 is essential for both effector translocation and the actin rearrangements leading to invasome formation. Furthermore, we show that talin1, but not talin2, is required for inside-out activation of integrin ß1 during invasome formation. Finally, integrin-ß1-mediated outside-in signaling by FAK, Src, paxillin and vinculin is necessary for invasome formation. This is the first example of a bacterial entry process that fully exploits the bi-directional signaling capacity of integrin receptors in a talin1-specific manner.

Cutaneous epithelioid angiomatous nodule of the chest wall with expression of estrogen receptor: a mimic of carcinoma and a potential diagnostic pitfall.

Cutaneous epithelioid angiomatous nodule (CEAN) is a rare vascular proliferation that develops on the trunk and extremities. The lesion arises over weeks to months and affects both sexes without age predilection. Histologically, CEAN is characterized by a circumscribed proliferation of epithelioid endothelial cells in the superficial dermis with a background of lymphocytes, plasma cells and eosinophils. The epithelioid cells are positive for CD31, CD34 and/or D2-40. We report a case of CEAN that had remained stable for more than 30 years on the chest wall of a woman with a history of breast cancer. The lesional cells were epithelioid in appearance and positive for estrogen receptor (ER), raising suspicion for breast carcinoma. However, the cells were positive for CD31, CD34, D2-40 and EMA (epithelial membrane antigen); they were negative for cytokeratins, carcinoembryonic antigen (CEA), CD1a, gross cystic disease fluid protein (GCDFP-15), S-100, a melanocytic cocktail, HHV-8 and progesterone receptor. The histologic and immunohistochemical features, including a low proliferation index (10% by Ki-67), helped to distinguish this lesion from carcinoma and other vascular lesions. This is the most comprehensive immunohistochemical profile reported for CEAN to date and the first time that ER expression has been described.

The head of Bartonella adhesin A is crucial for host cell interaction of Bartonella henselae.

Human pathogenic Bartonella henselae cause cat scratch disease and vasculoproliferative disorders (e.g. bacillary angiomatosis). Expression of Bartonella adhesin A (BadA) is crucial for bacterial autoagglutination, adhesion to host cells, binding to extracellular matrix proteins and proangiogenic reprogramming via activation of hypoxia inducible factor (HIF)-1. Like the prototypic Yersinia adhesin A, BadA belongs to the class of trimeric autotransporter adhesins and is constructed modularly consisting of a head, a long and repetitive neck-stalk module and a membrane anchor. Until now, the exact biological role of these domains is not known. Here, we analysed the function of the BadA head by truncating the repetitive neck-stalk module of BadA (B. henselae badA(-)/pHN23). Like B. henselae Marseille wild type, B. henselae badA(-)/pHN23 showed autoagglutination, adhesion to collagen and endothelial cells and activation of HIF-1 in host cells. Remarkably, B. henselae badA(-)/pHN23 did not bind to fibronectin (Fn) suggesting a crucial role of the deleted stalk domain in Fn binding. Additionally, the recombinantly expressed BadA head adhered to human umbilical vein endothelial cells and to a lesser degree to epithelial (HeLa 229) cells. Our data suggest that the head represents the major functional domain of BadA responsible for host adhesion and angiogenic reprogramming.

Evidence of a leading role for VEGF in Bartonella henselae-induced endothelial cell proliferations.

Bartonella henselae causes the vasculoproliferative disorders bacillary angiomatosis (BA) and bacillary peliosis (BP). The pathomechanisms of these tumorous proliferations are unknown. Our results suggest a novel bacterial two-step pathogenicity strategy, in which the pathogen triggers growth factor production for subsequent proliferation of its own host cells. In fact, B. henselae induces host cell production of the angiogenic factor vascular endothelial growth factor (VEGF), leading to proliferation of endothelial cells. The presence of B. henselae pili was associated with host cell VEGF production, as a Pil- mutant of B. henselae was unable to induce VEGF production. In turn, VEGF-stimulated endothelial cells promoted the growth of B. henselae. Immunohistochemistry for VEGF in specimens from patients with BA or BP revealed increased VEGF expression in vivo. These findings suggest a novel bacteria-dependent mechanism of tumour growth.

Tenascin-C expression in ultrastructurally defined angiogenic and vasculogenic lesions.

Tenascin-C (TN) is an extracellular matrix glycoprotein expressed during embryogenesis. Its distribution is restricted in normal adult tissues and is upregulated in tumors and inflammatory conditions. Twenty-five specimens were studied, including 7 reactive vascular lesions (6 cases of granulation tissue and 1 case of bacillary angiomatosis), and 18 vascular tumors (6 angiosarcomas, 7 hemangioendotheliomas, and 5 AIDS-related nodular type Kaposi's sarcomas). Formalin fixed-paraffin-embedded tissues were stained with monoclonal antibody to TN (DAKO) and with MIB-1 (AMAC). Heterogeneous expression of TN immunoreactivity was seen in all cases, with a diffuse pattern in bacillary angiomatosis and most granulation tissue cases and a focal pattern in angiosarcoma and most hemangioendothelioma cases. Kaposi's sarcoma cases showed both a focal and diffuse pattern of distribution. In most cases proliferation indices (PI) did not correlate with TN expression. Electron microscopy demonstrated active angiogenesis in bacillary angiomatosis and granulation tissue and vasculogenesis in angiosarcoma and hemangioendothelioma. The study demonstrated positive TN expression in reactive lesions with angiogenesis (granulation tissue and bacillary angiomatosis) and neoplastic lesions showing vasculogenesis (angiosarcoma and hemangioendothelioma), although with a different pattern of distribution. These results suggest that TN might be an important extracellular matrix glycoprotein in angiogenesis and vasculogenesis.