Jean Yannis Perentes

In vivo imaging of extracellular matrix remodeling by tumor-associated fibroblasts

Here we integrated multiphoton laser scanning microscopy and the registration of second harmonic generation images of collagen fibers to overcome difficulties in tracking stromal cell-matrix interactions for several days in live mice. We show that the matrix-modifying hormone relaxin increased tumor-associated fibroblast (TAF) interaction with collagen fibers by stimulating β1-integrin activity, which is necessary for fiber remodeling by matrix metalloproteinases.

Cancer Cell Death Enhances the Penetration and Efficacy of Oncolytic Herpes Simplex Virus in Tumors

The success of tumor oncolytic virotherapy is limited by the poor penetration of virus in tumors. Interstitial collagen fibers and the narrow spacing between cancer cells are major barriers hindering the movement of large viral particles. To bypass the cellular barrier, we tested the hypothesis that the void space produced by cancer cell apoptosis enhances the initial spread and efficacy of oncolytic herpes simplex virus (HSV). In mice with mammary tumors, apoptosis was induced by doxycycline-regulated expression/activation of CD8/caspase-8, paclitaxel, or paclitaxel plus tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). In both collagen-poor and collagen-rich tumors, apoptosis or necrosis increased the initial intratumoral spread of HSV. Compared with the isolated pattern of HSV infection generally located in the center of control tumors, apoptosis induction and a single i.t. injection of virus produced an interconnected and diffuse pattern of infection, which extended from the tumor center to the periphery. This interconnected pattern of viral infection correlated with the formation of void spaces and channel-like structures in apoptosis-rich tumor areas. We also show that the i.t. injection of HSV after caspase-8 activation or paclitaxel-TRAIL pretreatment retards tumor growth, whereas HSV administration before tumor cell death induction did not improve therapeutic efficacy. Hence, our findings show that the induction of cancer cell death before the injection of oncolytic HSV enhances intratumoral virus delivery/penetration and antitumor efficacy.

Blockade of VEGFR2 and Not VEGFR1 Can Limit Diet-Induced Fat Tissue Expansion: Role of Local versus Bone Marrow-Derived Endothelial Cells

Background We investigated if new vessel formation in fat involves the contribution of local tissue-derived endothelial cells (i.e., angiogenesis) or bone marrow-derived cells (BMDCs, i.e. vasculogenesis) and if antiangiogenic treatment by blockade of vascular endothelial growth factor (VEGF) receptors can prevent diet-induced obesity (DIO). Methodology/Principal Findings We performed restorative bone marrow transplantation into wild-type mice using transgenic mice expressing green fluorescent protein (GFP) constitutively (driven by β-actin promoter) or selectively in endothelial cells (under Tie2 promoter activation) as donors. The presence of donor BMDCs in recipient mice was investigated in fat tissue vessels after DIO using in vivo and ex vivo fluorescence microscopy. We investigated the roles of VEGF receptors 1 and 2 (VEGFR1/VEGFR2) by inducing DIO in mice and treating them with blocking monoclonal antibodies. We found only marginal (less than 1%) incorporation of BMDCs in fat vessels during DIO. When angiogenesis was inhibited by blocking VEGFR2 in mice with DIO, treated mice had significantly lower body weights than control animals. In contrast, blocking VEGFR1 had no discernable effect on the weight gain during DIO. Conclusions/Significance Formation of new vessels in fat tissues during DIO is largely due to angiogenesis rather than de novo vasculogenesis. Antiangiogenic treatment by blockade of VEGFR2 but not VEGFR1 may limit adipose tissue expansion.

Cancer cell associated MT1-MMP promotes blood vessel invasion and distant metastasis in triple-negative mammary tumors

Functional roles for the cancer cell-associated membrane type I matrix metalloproteinase (MT1-MMP) during early steps of the metastatic cascade in primary tumors remain unresolved. In an effort to determine its significance, we determined the in vivo effects of RNAi-mediated downregulation in mammary cancer cells on the migration, blood and lymphatic vessel invasion (LVI), and lymph node and lung metastasis. We also correlated the expression of cancer cell MT1-MMP with blood vessel invasion (BVI) in 102 breast cancer biopsies. MT1-MMP downregulation in cancer cells decreased lung metastasis without affecting primary tumor growth. The inhibition of lung metastasis correlated with reduced cancer cell migration and BVI. Furthermore, cancer cell-expressed MT1-MMP upregulated the expression of MT1-MMP in vascular endothelial cells, but did not affect MT1-MMP expression in lymphatic endothelial cells, LVI, or lymph node metastasis. Of clinical importance, we observed that elevated MT1-MMP expression correlated with BVI in biopsies from triple-negative breast cancers (TNBC), which have a poor prognosis and high incidence of distant metastasis, relative to other breast cancer subtypes. Together, our findings established that MT1-MMP activity in breast tumors is essential for BVI, but not LVI, and that MT1-MMP should be further explored as a predictor and therapeutic target of hematogenous metastasis in TNBC patients.

Lack of Telopeptides in Fibrillar Collagen I Promotes the Invasion of a Metastatic Breast Tumor Cell Line

Defective fibrillar collagen polymerization in primary tumors has been correlated with increased metastasis. However, it is unclear how collagen organization influences tumor invasion. In this study, we show that collagen I polymerized without telopeptides (the flanking regions of collagen molecules) can differentially affect the three-dimensional migration of mammary carcinoma cells. MDA-MB-231 cells capable of proteolytic degradation and mesenchymal motion, invaded telopeptide-intact and telopeptide-free collagen gels to the same extent. In contrast, MDA-MB-435S cells, with typical features of amoeboid cells (poor collagenolytic activity, rounded cell morphology), were 5-fold more invasive in telopeptide-free than telopeptide-intact collagen. A fraction of the MDA-MB-435S cells that invaded telopeptide-intact or telopeptide-free collagen had a rounded morphology; however, in telopeptide-free collagen, a significant fraction of the cells switched from a rounded to elongated morphology (protrusion formation). The dynamic changes in cellular shape facilitated MDA-MB-435S locomotion through the narrow interfiber gaps, which were smaller than cell diameters. Based on the spherical morphology of MDA-MB-435S cells, we tested if the changes in cell shape and invasion were related to RhoA-ROCK activity; GTP-bound RhoA was measured in pull-down assays. RhoA activity was 1.8-fold higher for MDA-MB-435S cells seeded on telopeptide-free than telopeptide-intact collagen. Y27632 inhibition of ROCK, a Rho effector, significantly reduced the changes in cellular morphodynamics and the invasion of MDA-MB-435S cells but did not alter the invasion of MDA-MB-231 cells. Thus, the higher RhoA activity of MDA-MB-435S cells in telopeptide-free collagen enhances the changes in cellular morphodynamics associated with motility and invasion.

Visualizing anti-tumor immune responses in vivo

Real-time imaging of stromal and immune cells in tumors is an emerging field that will greatly help us to understand the role of these non-malignant tumor components in tumor progression and therapy

Pyrrolidine dithiocarbamate administered during ex-vivo lung perfusion promotes rehabilitation of injured donor rat lungs obtained after prolonged warm ischemia

Damaged lung grafts obtained after circulatory death (DCD lungs) and warm ischemia may be at high risk of reperfusion injury after transplantation. Such lungs could be pharmacologically reconditioned using ex-vivo lung perfusion (EVLP). Since acute inflammation related to the activation of nuclear factor kappaB (NF-κB) is instrumental in lung reperfusion injury, we hypothesized that DCD lungs might be treated during EVLP by pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF-κB. Rat lungs exposed to 1h warm ischemia and 2 h cold ischemia were subjected to EVLP during 4h, in absence (CTRL group, N = 6) or in presence of PDTC (2.5g/L, PDTC group, N = 6). Static pulmonary compliance (SPC), peak airway pressure (PAWP), pulmonary vascular resistance (PVR), and oxygenation capacity were determined during EVLP. After EVLP, we measured the weight gain of the heart-lung block (edema), and the concentration of LDH (cell damage), proteins (permeability edema) and of the cytokines IL-6, TNF-α and CINC-1 in bronchoalveolar lavage (BAL), and we evaluated NF-κB activation by the degree of phosphorylation and degradation of its inhibitor IκBα in lung tissue. In CTRL, we found significant NF-κB activation, lung edema, and a massive release of LDH, proteins and cytokines. SPC significantly decreased, PAWP and PVR increased, while oxygenation tended to decrease. Treatment with PDTC during EVLP inhibited NF-κB activation, did not influence LDH release, but markedly reduced lung edema and protein concentration in BAL, suppressed TNFα and IL-6 release, and abrogated the changes in SPC, PAWP and PVR, with unchanged oxygenation. In conclusion, suppression of innate immune activation during EVLP using the NF-κB inhibitor PDTC promotes significant improvement of damaged rat DCD lungs. Future studies will determine if such rehabilitated lungs are suitable for in vivo transplantation.

Management of bilateral necrotizing bronchial dehiscence after a double lung transplantation

Abstract Necrotizing bronchial dehiscence following lung transplantation is a rare and deadly complication with no strict management consensus. Here, we report the case of a patient who underwent bilateral sequential lung transplantation for cystic fibrosis through a clamshell incision and developed, on postoperative day 17, complete bilateral anastomotic dehiscence. The latter was attributed to a Pseudomonas aeruginosa and Aspergillus necrotizing infection. The patient was managed surgically using a bilateral posterolateral thoracotomy approach with resection of the bronchial margins, end-to-end re-anastomosis and intercostal muscle coverage. Appropriate antibiotherapy was initiated and the airway/patient outcomes were favorable.

Personalized surgery for the management of pulmonary metastasis

Since the first report of pulmonary metastasectomy for colorectal cancer (CRC) by Blalock in 1946, many surgical adjustments have been suggested (1). Over the past years, growing evidence has shown that a subset of patients with pulmonary metastases (PMs) may benefit from a curative resection, provided some strict criteria are met (2,3).

Clinical outcome and risk factors for complications after pulmonary segmentectomy by video-assisted thoracoscopic surgery: results of an initial experience

Background Pulmonary anatomical segmentectomies are increasingly being done via video-assisted thoracoscopic surgery (VATS). We analyzed clinical outcomes and risk factors for post-operative complications after pulmonary segmentectomy by VATS was introduced in two institutions. Methods We retrospectively reviewed records of all patients who underwent anatomical pulmonary segmentectomy by VATS from 2014 to 2016 at the university hospitals of Geneva and Lausanne in Switzerland. Results One hundred twenty-nine patients (64 men; median age 68 years, range, 29-85 years) underwent anatomical VATS segmentectomy for primary lung tumors (n=100), metastases (n=16) and benign lesions (n=13). The overall 30-day mortality and morbidity rates were 0.8% and 31%, respectively. The reoperation rate was 4.7% [indications: hemothorax 2, prolonged air leak (PAL) 2, segmental torsion 1, empyema 1]. Chest drainage lasted for a median of 2 days (range, 1-33 days) and patients were discharged from the hospital after a median of 6 days (range, 2-37 days). Postoperative complications were mainly associated with chronic obstructive pulmonary disease (COPD) [odds ratio (OR) 2.54 and 95% confidence interval (95% CI), 1.18-5.47], and smoking pack-years >50 units (OR 5.27; 95% CI, 1.68-16.55). Nine patients (9%) presented with distant recurrences. Nodule size >2 cm was associated with decreased disease-free survival (DFS) (P=0.04). There was no association between surgical experience in VATS segmentectomy and DFS or postoperative complications. Conclusions Segmentectomies can be safely performed by VATS in an initial experience and result in favorable clinical outcome. COPD and smoking pack-years are associated with an increased risk of complications.