A RAD51 functional assay as a candidate test for homologous recombination deficiency in ovarian cancer.

RATIONALE: Homologous recombination deficiency (HRD), defined as BRCA1/2 mutation (BRCAmut) or high genomic instability, is used to identify ovarian cancer (OC) patients most likely to benefit from PARP inhibitors. While these tests are useful, they are imperfect. Another approach is to measure the capacity of tumor cells to form RAD51 foci in the presence of DNA damage using an immunofluorescence assay (IF). We aimed to describe for the first time this assay in OC and correlate it to platinum response and BRCAmut. METHODS: Tumor samples were prospectively collected from the randomized CHIVA trial of neoadjuvant platinum +/- nintedanib. IF for RAD51, GMN and gH2AX was performed on FFPE blocks. Tumors were considered RAD51-low if ≤10% of GMN-positive tumor cells had ≥5 RAD51 foci. BRCAmut were identified by NGS. RESULTS: 155 samples were available. RAD51 assay was contributive for 92% of samples and NGS available for 77%. gH2AX foci confirmed the presence of significant basal DNA damage. 54% of samples were considered HRD by RAD51 and presented higher overall response rates to neoadjuvant platinum (P = 0.04) and longer progression-free survival (P = 0.02). In addition, 67% of BRCAmut were HRD by RAD51. Among BRCAmut, RAD51-high tumors seem to harbor poorer response to chemotherapy (P = 0.02). CONCLUSIONS: We evaluated a functional assay of HR competency. OC demonstrate high levels of DNA damage, yet 54% fail to form RAD51 foci. These RAD51-low OC tend to be more sensitive to neoadjuvant platinum. The RAD51 assay also identified a subset of RAD51-high BRCAmut tumors with unexpected poor platinum response.

Resident PW1+ Progenitor Cells Participate in Vascular Remodeling During Pulmonary Arterial Hypertension.

RATIONALE: Pulmonary arterial hypertension is characterized by vascular remodeling and neomuscularization. PW1(+) progenitor cells can differentiate into smooth muscle cells (SMCs) in vitro. OBJECTIVE: To determine the role of pulmonary PW1(+) progenitor cells in vascular remodeling characteristic of pulmonary arterial hypertension. METHODS AND RESULTS: We investigated their contribution during chronic hypoxia-induced vascular remodeling in Pw1(nLacZ+/-) mouse expressing ß-galactosidase in PW1(+) cells and in differentiated cells derived from PW1(+) cells. PW1(+) progenitor cells are present in the perivascular zone in rodent and human control lungs. Using progenitor markers, 3 distinct myogenic PW1(+) cell populations were isolated from the mouse lung of which 2 were significantly increased after 4 days of chronic hypoxia. The number of proliferating pulmonary PW1(+) cells and the proportion of ß-gal(+) vascular SMC were increased, indicating a recruitment of PW1(+) cells and their differentiation into vascular SMC during early chronic hypoxia-induced neomuscularization. CXCR4 inhibition using AMD3100 prevented PW1(+) cells differentiation into SMC but did not inhibit their proliferation. Bone marrow transplantation experiments showed that the newly formed ß-gal(+) SMC were not derived from circulating bone marrow-derived PW1(+) progenitor cells, confirming a resident origin of the recruited PW1(+) cells. The number of pulmonary PW1(+) cells was also increased in rats after monocrotaline injection. In lung from pulmonary arterial hypertension patients, PW1-expressing cells were observed in large numbers in remodeled vascular structures. CONCLUSIONS: These results demonstrate the existence of a novel population of resident SMC progenitor cells expressing PW1 and participating in pulmonary hypertension-associated vascular remodeling.

Abnormalities of capillary microarchitecture in a rat model of coronary ischemic congestive heart failure.

The aim of the present study is to explore the role of capillary disorder in coronary ischemic congestive heart failure (CHF). CHF was induced in rats by aortic banding plus ischemia-reperfusion followed by aortic debanding. Coronary arteries were perfused with plastic polymer containing fluorescent dye. Multiple fluorescent images of casted heart sections and scanning electric microscope of coronary vessels were obtained to characterize changes in the heart. Cardiac function was assessed by echocardiography and in vivo hemodynamics. Stenosis was found in all levels of the coronary arteries in CHF. Coronary vasculature volume and capillary density in remote myocardium were significantly increased in CHF compared with control. This occurred largely in microvessels with a diameter of ≤3 µm. Capillaries in CHF had a tortuous structure, while normal capillaries were linear. Capillaries in CHF had inconsistent diameters, with assortments of narrowed and bulged segments. Their surfaces appeared rough, potentially indicating endothelial dysfunction in CHF. Segments of main capillaries between bifurcations were significantly shorter in length in CHF than in control. Transiently increasing preload by injecting 50 µl of 30% NaCl demonstrated that the CHF heart had lower functional reserve; this may be associated with congestion in coronary microcirculation. Ischemic coronary vascular disorder is not limited to the main coronary arteries, as it occurs in arterioles and capillaries. Capillary disorder in CHF included stenosis, deformed structure, proliferation, and roughened surfaces. This disorder in the coronary artery architecture may contribute to the reduction in myocyte contractility in the setting of heart failure.

Stem cell factor gene transfer promotes cardiac repair after myocardial infarction via in situ recruitment and expansion of c-kit+ cells.

RATIONALE: There is growing evidence that the myocardium responds to injury by recruiting c-kit(+) cardiac progenitor cells to the damage tissue. Even though the ability of exogenously introducing c-kit(+) cells to injured myocardium has been established, the capability of recruiting these cells through modulation of local signaling pathways by gene transfer has not been tested. OBJECTIVE: To determine whether stem cell factor gene transfer mediates cardiac regeneration in a rat myocardial infarction model, through survival and recruitment of c-kit(+) progenitors and cell-cycle activation in cardiomyocytes, and explore the mechanisms involved. METHODS AND RESULTS: Infarct size, cardiac function, cardiac progenitor cells recruitment, fibrosis, and cardiomyocyte cell-cycle activation were measured at different time points in controls (n=10) and upon stem cell factor gene transfer (n=13) after myocardial infarction. We found a regenerative response because of stem cell factor overexpression characterized by an enhancement in cardiac hemodynamic function: an improvement in survival; a reduction in fibrosis, infarct size and apoptosis; an increase in cardiac c-kit(+) progenitor cells recruitment to the injured area; an increase in cardiomyocyte cell-cycle activation; and Wnt/ß-catenin pathway induction. CONCLUSIONS: Stem cell factor gene transfer induces c-kit(+) stem/progenitor cell expansion in situ and cardiomyocyte proliferation, which may represent a new therapeutic strategy to reverse adverse remodeling after myocardial infarction.

Spatial Profiling of Ovarian Carcinoma and Tumor Microenvironment Evolution under Neoadjuvant Chemotherapy.

PURPOSE: This study investigates changes in CD8+ cells, CD8+/Foxp3 ratio, HLA I expression, and immune coregulator density at diagnosis and upon neoadjuvant chemotherapy (NACT), correlating changes with clinical outcomes. EXPERIMENTAL DESIGN: Multiplexed immune profiling and cell clustering analysis were performed on paired matched ovarian cancer samples to characterize the immune tumor microenvironment (iTME) at diagnosis and under NACT in patients enrolled in the CHIVA trial (NCT01583322). RESULTS: Several immune cell (IC) subsets and immune coregulators were quantified pre/post-NACT. At diagnosis, patients with higher CD8+ T cells and HLA I+-enriched tumors were associated with a better outcome. The CD8+/Foxp3+ ratio increased significantly post-NACT in favor of increased immune surveillance, and the influx of CD8+ T cells predicted better outcomes. Clustering analysis stratified pre-NACT tumors into four subsets: high Binf, enriched in B clusters; high Tinf and low Tinf, according to their CD8+ density; and desert clusters. At baseline, these clusters were not correlated with patient outcomes. Under NACT, tumors were segregated into three clusters: high BinfTinf, low Tinf, and desert. The high BinfTinf, more diverse in IC composition encompassing T, B, and NK cells, correlated with improved survival. PDL1 was rarely expressed, whereas TIM3, LAG3, and IDO1 were more prevalent. CONCLUSIONS: Several iTMEs exist during tumor evolution, and the NACT impact on iTME is heterogeneous. Clustering analysis of patients unravels several IC subsets within ovarian cancer and can guide future personalized approaches. Targeting different checkpoints such as TIM3, LAG3, and IDO1, more prevalent than PDL1, could more effectively harness antitumor immunity in this anti-PDL1-resistant malignancy.

Immune predictors of response to immune checkpoint inhibitors in mismatch repair-deficient endometrial cancer.

BACKGROUND: Patients with mismatch repair-deficient (MMRd) endometrial cancer (EC) can derive great benefit from immune checkpoint inhibitors (ICI). However not all responses and predictors of primary resistance are lacking. METHODS: We compared the immune tumor microenvironment of MMRd EC ICI-responders (Rs) and ICI non-responders (NRs), using spatial multiplexed immune profiling and unsupervised hierarchical clustering analysis. RESULTS: Overall, NRs exhibited drastically lower CD8+, absent terminally differentiated T cells, lack of mature tertiary lymphoid structures and dendritic cells, as well as loss of human leukocyte antigen class I. However, no single marker could predict R versus NR with confidence. Clustering analysis identified a combination of four immune features that demonstrated that accurately predicted ICI response, with a discriminative power of 92%. Finally, 80% of NRs lacked programmed death-ligand 1, however, 60% exhibited another actionable immune checkpoint (T-cell immunoglobulin and mucin containing protein-3, indoleamine 2,3-dioxygenase 1, or lymphocyte activation gene 3). CONCLUSIONS: These findings underscore the potential of immune tumor microenvironment features for identifying patients with MMRd EC and primary resistance to ICI who should be oriented towards trials testing novel immunotherapeutic combinations.

The impact of pressure overload on coronary vascular changes following myocardial infarction in rats.

This study investigates the impact of pressure overload on vascular changes after myocardial infarction (MI) in rats. To evaluate the effect of pressure overload, MI was induced in three groups: 1) left coronary artery ligation for 1 mo (MI-1m), 2) ischemia 30 min/reperfusion for 1 mo (I/R-1m), and 3) ischemia-reperfusion (I/R) was performed after pressure overload induced by aortic banding for 2 mo; 1 mo post-I/R, aortic constriction was released (Ab+I/R+DeAb). Heart function was assessed by echocardiography and in vivo hemodynamics. Resin casting and three-dimensional imaging with microcomputed tomography were used to characterize changes in coronary vasculature. TTC (triphenyltetrazohum chloride) staining and Masson's Trichrome were conducted in parallel experiments. In normal rats, MI induced by I/R and permanent occlusion was transmural or subendocardial. Occluded arterial branches vanished in MI-1m rats. A short residual tail was retained, distal to the occluded site in the ischemic area in I/R-1m hearts. Vascular pathological changes in transmural MI mostly occurred in ischemic areas and remote vasculature remained normal. In pressure overloaded rats, I/R injury induced a sub-MI in which ischemia was transmural, but myocardium in the involved area had survived. The ischemic arterial branches were preserved even though the capillaries were significantly diminished and the pathological changes were extended to remote areas, characterized by fibrosis, atrial thrombus, and pulmonary edema in the Ab+I/R+DeAb group. Pressure overload could increase vascular tolerance to I/R injury, but also trigger severe global ventricular fibrosis and results in atrial thrombus and pulmonary edema.

RAD51 as a biomarker for homologous recombination deficiency in high-grade serous ovarian carcinoma: robustness and interobserver variability of the RAD51 test.

The RAD51 test is emerging as a promising biomarker for the assessment of functional homologous recombination deficiency (HRD). Yet, the robustness and reproducibility of the immunofluorescence-based RAD51 test, in different academic laboratories, have not been systematically investigated. Therefore, we tested the performance of the RAD51 assay in formalin-fixed paraffin-embedded (FFPE) high-grade serous ovarian carcinoma (HGSOC) samples in four European laboratories. Here, we confirm that subtle differences in staining procedures result in low variability of RAD51 and γH2AX scores. However, substantial variability in RAD51 scoring was observed in some samples, likely due to complicating technical and biological features, such as high RAD51 signal-to-noise ratio and RAD51 heterogeneity. These results support the need to identify and perform additional quality control steps and/or automating image analysis. Altogether, resolving technical issues should be a priority, as identifying tumours with functional HRD is urgently needed to guide the individual treatment of HGSOC patients. Follow-up studies are needed to define the key tissue quality requirements to assess HRD by RAD51 in FFPE tumour samples, as this test could help in guiding the individual treatment of HGSOC patients.

A new model of congestive heart failure in rats.

Current rodent models of ischemia/infarct or pressure-volume overload are not fully representative of human heart failure. We developed a new model of congestive heart failure (CHF) with both ischemic and stress injuries combined with fibrosis in the remote myocardium. Sprague-Dawley male rats were used. Ascending aortic banding (Ab) was performed to induce hypertrophy. Two months post-Ab, ischemia-reperfusion (I/R) injury was induced by ligating the left anterior descending (LAD) artery for 30 min. Permanent LAD ligation served as positive controls. A debanding (DeAb) procedure was performed after Ab or Ab + I/R to restore left ventricular (LV) loading properties. Cardiac function was assessed by echocardiography and in vivo hemodynamic analysis. Myocardial infarction (MI) size and myocardial fibrosis were assessed. LV hypertrophy was observed 4 mo post-Ab; however, systolic function was preserved. LV hypertrophy regressed within 1 mo after DeAb. I/R for 2 mo induced a small to moderate MI with mild impairment of LV function. Permanent LAD ligation for 2 mo induced large MI and significant cardiac dysfunction. Ab for 2 mo followed by I/R for 2 mo (Ab + I/R) resulted in moderate MI with significantly reduced ejection fraction (EF). DeAb post Ab + I/R to reduce afterload could not restore cardiac function. Perivascular fibrosis in remote myocardium after Ab + I/R + DeAb was associated with decreased cardiac function. We conclude that Ab plus I/R injury with aortic DeAb represents a novel model of CHF with increased fibrosis in remote myocardium. This model will allow the investigation of vascular and fibrotic mechanisms in CHF characterized by low EF, dilated LV, moderate infarction, near-normal aortic diameter, and reperfused coronary arteries.

Anti-integrin αv therapy improves cardiac fibrosis after myocardial infarction by blunting cardiac PW1+ stromal cells.

There is currently no therapy to limit the development of cardiac fibrosis and consequent heart failure. We have recently shown that cardiac fibrosis post-myocardial infarction (MI) can be regulated by resident cardiac cells with a fibrogenic signature and identified by the expression of PW1 (Peg3). Here we identify αV-integrin (CD51) as an essential regulator of cardiac PW1+ cells fibrogenic behavior. We used transcriptomic and proteomic approaches to identify specific cell-surface markers for cardiac PW1+ cells and found that αV-integrin (CD51) was expressed in almost all cardiac PW1+ cells (93% ± 1%), predominantly as the αVß1 complex. αV-integrin is a subunit member of the integrin family of cell adhesion receptors and was found to activate complex of latent transforming growth factor beta (TGFß at the surface of cardiac PW1+ cells. Pharmacological inhibition of αV-integrin reduced the profibrotic action of cardiac PW1+CD51+ cells and was associated with improved cardiac function and animal survival following MI coupled with a reduced infarct size and fibrotic lesion. These data identify a targetable pathway that regulates cardiac fibrosis in response to an ischemic injury and demonstrate that pharmacological inhibition of αV-integrin could reduce pathological outcomes following cardiac ischemia.

Fibrogenic Potential of PW1/Peg3 Expressing Cardiac Stem Cells.

BACKGROUND: Pw1 gene expression is a marker of adult stem cells in a wide range of tissues. PW1-expressing cells are detected in the heart but are not well characterized. OBJECTIVES: The authors characterized cardiac PW1-expressing cells and their cell fate potentials in normal hearts and during cardiac remodeling following myocardial infarction (MI). METHODS: A human cardiac sample was obtained from a patient presenting with reduced left ventricular (LV) function following a recent MI. The authors used the PW1nLacZ+/- reporter mouse to identify, track, isolate, and characterize PW1-expressing cells in the LV myocardium in normal and ischemic conditions 7 days after complete ligature of the left anterior descending coronary artery. RESULTS: In both human and mouse ischemic hearts, PW1 expression was found in cells that were mainly located in the infarct and border zones. Isolated cardiac resident PW1+ cells form colonies and have the potential to differentiate into multiple cardiac and mesenchymal lineages, with preferential differentiation into fibroblast-like cells but not into cardiomyocytes. Lineage-tracing experiments revealed that PW1+ cells differentiated into fibroblasts post-MI. Although the expression of c-Kit and PW1 showed little overlap in normal hearts, a marked increase in cells coexpressing both markers was observed in ischemic hearts (0.1 ± 0.0% in control vs. 5.7 ± 1.2% in MI; p < 0.001). In contrast to the small proportion of c-Kit+/PW1- cells that showed cardiogenic potential, c-Kit+/PW1+ cells were fibrogenic. CONCLUSIONS: This study demonstrated the existence of a novel population of resident adult cardiac stem cells expressing PW1+ and their involvement in fibrotic remodeling after MI.

ZAP-70 upregulation in transformed B cells after early pre-BI cell transplant into NOD/SCID mice.

Understanding of the signal transduction pathways that lead to B cell development is of extreme interest to learn how alterations in these pathways might initiate malignant transformation. Long-term cultured early pre-BI cells can differentiate into IgM+ B cells after transplant into NOD/SCID mice, offering the possibility to explore checkpoints in B cell development. Using DNA microarray and Western blot analysis of IgM+ B cells vs parental early pre-BI cells, we demonstrated that zeta-associated protein 70 (ZAP-70) is upregulated in our B cell differentiation model. Unlike parental ZAP-70- early pre-BI cells, ZAP-70+ IgM+ B cells exhibited a transformed phenotype, as indicated by BCL-6 expression, a high Ki-67 proliferation index, resistance to IL-7 deprivation-induced apoptosis, and an increased repopulation rate in NOD/SCID mice. These data show the characterization and generation of a novel murine leukemia model with many similarities to human ZAP-70+ B cell chronic lymphocytic leukemia.

Stem cell factor gene transfer improves cardiac function after myocardial infarction in swine.

BACKGROUND: Stem cell factor (SCF), a ligand of the c-kit receptor, is a critical cytokine, which contributes to cell migration, proliferation, and survival. It has been shown that SCF expression increases after myocardial infarction (MI) and may be involved in cardiac repair. The aim of this study was to determine whether gene transfer of membrane-bound human SCF improves cardiac function in a large animal model of MI. METHODS AND RESULTS: A transmural MI was created by implanting an embolic coil in the left anterior descending artery in Yorkshire pigs. One week after the MI, the pigs received direct intramyocardial injections of either a recombinant adenovirus encoding for SCF (Ad.SCF, n=9) or ß-gal (Ad.ß-gal, n=6) into the infarct border area. At 3 months post-MI, ejection fraction increased by 12% relative to baseline after Ad.SCF therapy, whereas it decreased by 4.2% (P=0.004) in pigs treated with Ad.ß-gal. Preload-recruitable stroke work was significantly higher in pigs after SCF treatment (Ad.SCF, 55.5±11.6 mm Hg versus Ad.ß-gal, 31.6±12.6 mm Hg, P=0.005), indicating enhanced cardiac function. Histological analyses confirmed the recruitment of c-kit(+) cells as well as a reduced degree of apoptosis 1 week after Ad.SCF injection. In addition, increased capillary density compared with pigs treated with Ad.ß-gal was found at 3 months and suggests an angiogenic role of SCF. CONCLUSIONS: Local overexpression of SCF post-MI induces the recruitment of c-kit(+) cells at the infarct border area acutely. In the chronic stages, SCF gene transfer was associated with improved cardiac function in a preclinical model of ischemic cardiomyopathy.

Stimulating myocardial regeneration with periostin Peptide in large mammals improves function post-myocardial infarction but increases myocardial fibrosis.

AIMS: Mammalian myocardium has a finite but limited capacity to regenerate. Experimentally stimulating proliferation of cardiomyocytes with extracellular regeneration factors like periostin enhances cardiac repair in rodents. The aim of this study was to develop a safe method for delivering regeneration factors to the heart and to test the functional and structural effects of periostin peptide treatment in a large animal model of myocardial infarction (MI). METHODS AND RESULTS: We developed a controlled release system to deliver recombinant periostin peptide into the pericardial space. A single application of this method was performed two days after experimental MI in swine. Animals were randomly assigned to receive either saline or periostin peptide. Experimental groups were compared at baseline, day 2, 1 month and 3 months. Treatment with periostin peptide increased the EF from 31% to 41% and decreased by 22% the infarct size within 12 weeks. Periostin peptide-treated animals had newly formed myocardium strips within the infarct scar, leading to locally improved myocardial function. In addition the capillary density was increased in animals receiving periostin. However, periostin peptide treatment increased myocardial fibrosis in the remote region at one week and 12 weeks post-treatment. CONCLUSION: Our study shows that myocardial regeneration through targeted peptides is possible. However, in the case of periostin the effects on cardiac fibrosis may limit its clinical application as a viable therapeutic strategy.