A novel technique to estimate intravillous fetal vasculature on routine placenta histologic sections.

Placental histopathologic lesions are dichotomized into "present" or "absent" and have limited inter-rater reliability. Continuous metrics are needed to characterize placental health and function. Tissue sections (N = 64) of human placenta were stained with CD34 antibody and hematoxylin. Proportion of the villous space occupied by fetal vascular endothelium (%FVE; pixels positive for CD34/total pixels) was evaluated for effect sizes associated with pregnancy outcomes, smoking status, and subtypes of lesions (n = 30). Time to fixation>60 min significantly increased the quantification. Large effect sizes were found between %FVE and both preterm birth and intrauterine growth restriction. These results demonstrate proof-of-concept for this vascular estimation.

Epithelial plasticity and innate immune activation promote lung tissue remodeling following respiratory viral infection.

Epithelial plasticity has been suggested in lungs of mice following genetic depletion of stem cells but is of unknown physiological relevance. Viral infection and chronic lung disease share similar pathological features of stem cell loss in alveoli, basal cell (BC) hyperplasia in small airways, and innate immune activation, that contribute to epithelial remodeling and loss of lung function. We show that a subset of distal airway secretory cells, intralobar serous (IS) cells, are activated to assume BC fates following influenza virus infection. Injury-induced hyperplastic BC (hBC) differ from pre-existing BC by high expression of IL-22Ra1 and undergo IL-22-dependent expansion for colonization of injured alveoli. Resolution of virus-elicited inflammation results in BC to IS re-differentiation in repopulated alveoli, and increased local expression of protective antimicrobial factors, but fails to restore normal alveolar epithelium responsible for gas exchange.

Senescence of alveolar epithelial progenitor cells: a critical driver of lung fibrosis.

Pulmonary fibrosis comprises a range of chronic interstitial lung diseases (ILDs) that impose a significant burden on patients and public health. Among these, idiopathic pulmonary fibrosis (IPF), a disease of aging, is the most common and most severe form of ILD and is treated largely by lung transplantation. The lack of effective treatments to stop or reverse lung fibrosis-in fact, fibrosis in most organs-has sparked the need to understand causative mechanisms with the goal of identifying critical points for potential therapeutic intervention. Findings from many groups have indicated that repeated injury to the alveolar epithelium-where gas exchange occurs-leads to stem cell exhaustion and impaired alveolar repair that, in turn, triggers the onset and progression of fibrosis. Cellular senescence of alveolar epithelial progenitors is a critical cause of stemness failure. Hence, senescence impairs repair and thus contributes significantly to fibrosis. In this review, we discuss recent evidence indicating that senescence of epithelial progenitor cells impairs alveolar homeostasis and repair creating a profibrotic environment. Moreover, we discuss the impact of senescent alveolar epithelial progenitors, alveolar type 2 (AT2) cells, and AT2-derived transitional epithelial cells in fibrosis. Emerging evidence indicates that transitional epithelial cells are prone to senescence and, hence, are a new player involved in senescence-associated lung fibrosis. Understanding the complex interplay of cell types and cellular regulatory factors contributing to alveolar epithelial progenitor senescence will be crucial to developing targeted therapies to mitigate their downstream profibrotic sequelae and to promote normal alveolar repair.NEW & NOTEWORTHY With an aging population, lung fibrotic diseases are becoming a global health burden. Dysfunctional repair of the alveolar epithelium is a key causative process that initiates lung fibrosis. Normal alveolar regeneration relies on functional progenitor cells; however, the senescence of these cells, which increases with age, hinders their ability to contribute to repair. Here, we discuss studies on the control and consequence of progenitor cell senescence in fibrosis and opportunities for research.

Reciprocal interactions between alveolar progenitor dysfunction and aging promote lung fibrosis.

Aging is a critical risk factor in idiopathic pulmonary fibrosis (IPF). Dysfunction and loss of type 2 alveolar epithelial cells (AEC2s) with failed regeneration is a seminal causal event in the pathogenesis of IPF, although the precise mechanisms for their regenerative failure and demise remain unclear. To systematically examine the genomic program changes of AEC2s in aging and after lung injury, we performed unbiased single-cell RNA-seq analyses of lung epithelial cells from uninjured or bleomycin-injured young and old mice, as well as from lungs of IPF patients and healthy donors. We identified three AEC2 subsets based on their gene signatures. Subset AEC2-1 mainly exist in uninjured lungs, while subsets AEC2-2 and AEC2-3 emerged in injured lungs and increased with aging. Functionally, AEC2 subsets are correlated with progenitor cell renewal. Aging enhanced the expression of the genes related to inflammation, stress responses, senescence, and apoptosis. Interestingly, lung injury increased aging-related gene expression in AEC2s even in young mice. The synergistic effects of aging and injury contributed to impaired AEC2 recovery in aged mouse lungs after injury. In addition, we also identified three subsets of AEC2s from human lungs that formed three similar subsets to mouse AEC2s. IPF AEC2s showed a similar genomic signature to AEC2 subsets from bleomycin-injured old mouse lungs. Taken together, we identified synergistic effects of aging and AEC2 injury in transcriptomic and functional analyses that promoted fibrosis. This study provides new insights into the interactions between aging and lung injury with interesting overlap with diseased IPF AEC2 cells.

A compensatory RNase E variation increases Iron Piracy and Virulence in multidrug-resistant Pseudomonas aeruginosa during Macrophage infection.

During chronic cystic fibrosis (CF) infections, evolved Pseudomonas aeruginosa antibiotic resistance is linked to increased pulmonary exacerbations, decreased lung function, and hospitalizations. However, the virulence mechanisms underlying worse outcomes caused by antibiotic resistant infections are poorly understood. Here, we investigated evolved aztreonam resistant P. aeruginosa virulence mechanisms. Using a macrophage infection model combined with genomic and transcriptomic analyses, we show that a compensatory mutation in the rne gene, encoding RNase E, increased pyoverdine and pyochelin siderophore gene expression, causing macrophage ferroptosis and lysis. We show that iron-bound pyochelin was sufficient to cause macrophage ferroptosis and lysis, however, apo-pyochelin, iron-bound pyoverdine, or apo-pyoverdine were insufficient to kill macrophages. Macrophage killing could be eliminated by treatment with the iron mimetic gallium. RNase E variants were abundant in clinical isolates, and CF sputum gene expression data show that clinical isolates phenocopied RNase E variant functions during macrophage infection. Together these data show how P. aeruginosa RNase E variants can cause host damage via increased siderophore production and host cell ferroptosis but may also be targets for gallium precision therapy.

Plasma formation in holmium:YAG laser lithotripsy.

OBJECTIVES: During holmium:yttrium-aluminum-garnet (holmium:YAG) laser lithotripsy to break urinary stones, urologists frequently see flashes of light. As infrared laser pulses are invisible, what is the source of light? Here we studied the origin, characteristics, and some effects of flashes of light in laser lithotripsy. METHODS: Ultrahigh-speed video-microscopy was used to record single laser pulses at 0.2-1.0 J energy lasered with 242 µm glass-core-diameter fibers in contact with whole surgically retrieved urinary stones and hydroxyapatite (HA)-coated glass slides in air and water. Acoustic transients were measured with a hydrophone. Visible-light and infrared photodetectors resolved temporal profiles of visible-light emission and infrared-laser pulses. RESULTS: Temporal profiles of laser pulses showed intensity spikes of various duration and amplitude. The pulses were seen to produce dim light and bright sparks with submicrosecond risetime. The spark produced by the intensity spike at the beginning of laser pulse generated a shock wave in the surrounding liquid. The subsequent sparks were in a vapor bubble and generated no shock waves. Sparks enhanced absorption of laser radiation, indicative of plasma formation and optical breakdown. The occurrence and number of sparks varied even with the same urinary stone. Sparks were consistently observed at laser energy >0.5 J with HA-coated glass slides. The slides broke or cracked by cavitation with sparks in 63 ± 15% of pulses (1.0 J, N = 60). No glass-slide breakage occurred without sparks (1.0 J, N = 500). CONCLUSION: Unappreciated in previous studies, plasma formation with free-running long-pulse holmium:YAG lasers can be an additional physical mechanism of action in laser procedures.

Sulfated motifs in heparan sulfate inhibit Streptococcus pneumoniae adhesion onto fibronectin and attenuate corneal infection.

A large number of bacterial pathogens bind to host extracellular matrix (ECM) components. For example, many Gram-negative and Gram-positive pathogens express binding proteins for fibronectin (FN) on their cell surface. Mutagenesis studies of bacterial FN-binding proteins have demonstrated their importance in pathogenesis in preclinical animal models. However, means to draw on these findings to design therapeutic approaches that specifically target FN-bacteria interactions have not been successful because bacterial pathogens can elaborate several FN-binding proteins and also because FN is an essential protein and likely a nondruggable target. Here we report that select heparan compounds potently inhibit Streptococcus pneumoniae infection of injured corneas in mice. Using intact heparan sulfate (HS) and heparin (HP), heparinase-digested fragments of HS, HP oligosaccharides, and chemically or chemoenzymatically modified heparan compounds, we found that inhibition of S. pneumoniae corneal infection by heparan compounds is not mediated by simple charge effects but by a selective sulfate group. Removal of 2-O-sulfates significantly inhibited the ability of HP to inhibit S. pneumoniae corneal infection, whereas the addition of 2-O-sulfates to heparosan (H) significantly increased H's ability to inhibit bacterial corneal infection. Proximity ligation assays indicated that S. pneumoniae attaches directly to FN fibrils in the corneal epithelial ECM and that HS and HP specifically inhibit this binding interaction in a 2-O-sulfate-dependent manner. These data suggest that heparan compounds containing 2-O-sulfate groups protect against S. pneumoniae corneal infection by inhibiting bacterial attachment to FN fibrils in the subepithelial ECM of injured corneas. Moreover, 2-O-sulfated heparan compounds significantly inhibited corneal infection in immunocompromised hosts, by a clinical keratitis isolate of S. pneumoniae, and also when topically administered in a therapeutic manner. These findings suggest that the administration of nonanticoagulant 2-O-sulfated heparan compounds may represent a plausible approach to the treatment of S. pneumoniae keratitis.

The dynamic roles of the bladder tumour microenvironment.

Bladder cancer is a prevalent but currently understudied cancer type and patient outcomes are poor when it progresses to the muscle-invasive stage. Current research in bladder cancer focuses on the genetic and epigenetic alterations occurring within the urothelial cell compartment; however, the stromal compartment receives less attention. Dynamic changes and intercellular communications occur in the tumour microenvironment (TME) of the bladder - a new concept and niche that we designate as the bladder TME (bTME) - during tumour evolution, metastatic progression and in the context of therapeutic response. Collagens and their cognate receptors, the discoidin domain receptors, have a role in various steps of the metastatic cascade and in immune checkpoint resistance. Furthermore, the presence of another TME niche, the metastatic TME (met-TME), is a novel concept that could support divergent progression of metastatic colonization in different organs, resulting in distant metastases with distinct characteristics and genetics from the primary tumour. The stroma has divergent roles in mediating therapeutic response to BCG immunotherapy and immune checkpoint inhibitors, as well as conventional chemotherapy or trimodality therapy (that is, maximal transurethral resection of bladder tumour, chemotherapy and radiotherapy). The local bTME and distant met-TME are currently conceptually and therapeutically unexploited niches that should be actively investigated. New biological insights from these TMEs will enable rational design of strategies that co-target the tumour and stroma, which are expected to improve the outcomes of patients with advanced bladder cancer.

The ZIP8/SIRT1 axis regulates alveolar progenitor cell renewal in aging and idiopathic pulmonary fibrosis.

Type 2 alveolar epithelial cells (AEC2s) function as progenitor cells in the lung. We have shown previously that failure of AEC2 regeneration results in progressive lung fibrosis in mice and is a cardinal feature of idiopathic pulmonary fibrosis (IPF). In this study, we identified deficiency of a specific zinc transporter, SLC39A8 (ZIP8), in AEC2s from both IPF lungs and lungs of old mice. Loss of ZIP8 expression was associated with impaired renewal capacity of AEC2s and enhanced lung fibrosis. ZIP8 regulation of AEC2 progenitor function was dependent on SIRT1. Replenishment with exogenous zinc and SIRT1 activation promoted self-renewal and differentiation of AEC2s from lung tissues of IPF patients and old mice. Deletion of Zip8 in AEC2s in mice resulted in impaired AEC2 renewal, increased susceptibility to bleomycin injury, and development of spontaneous lung fibrosis. Therapeutic strategies to restore zinc metabolism and appropriate SIRT1 signaling could improve AEC2 progenitor function and mitigate ongoing fibrogenesis.

Abnormal respiratory progenitors in fibrotic lung injury.

Recent advances in single-cell RNA sequencing (scRNA-seq) and epithelium lineage labeling have yielded identification of multiple abnormal epithelial progenitor populations during alveolar type 2 (ATII) cell differentiation into alveolar type 1 (ATI) cells during regenerative lung post-fibrotic injury. These abnormal cells include basaloid/basal-like cells, ATII transition cells, and persistent epithelial progenitors (PEPs). These cells occurred and accumulated during the regeneration of distal airway and alveoli in response to both chronic and acute pulmonary injury. Among the alveolar epithelial progenitors, PEPs express a distinct Krt8+ phenotype that is rarely found in intact alveoli. However, post-injury, the Krt8+ phenotype is seen in dysplastic epithelial cells. Fully understanding the characteristics and functions of these newly found, injury-induced abnormal behavioral epithelial progenitors and the signaling pathways regulating their phenotype could potentially point the way to unique therapeutic targets for fibrosing lung diseases. This review summarizes recent advances in understanding these epithelial progenitors as they relate to uncovering regenerative mechanisms.

Placental growth factor as a diagnostic tool for placental mediated fetal growth restriction.

OBJECTIVE: Placental growth factor (PlGF) has shown promise in identification of placental fetal growth restriction (FGR). We aimed to investigate the association between PlGF and sonographic markers of placental dysfunction and assess its ability to diagnose FGR secondary to maternal vascular malperfusion (MVM). STUDY DESIGN: A retrospective study of singleton pregnancies with small for gestational age (SGA) fetuses, who had PlGF testing at 16-36 weeks. Fetuses with major chromosomal and/or structural anomalies and pregnancies with missing outcomes were excluded. Sonographic characteristics, perinatal outcomes and placental histopathology were compared between pregnancies with normal and low PlGF (<10th percentile for gestational age). The diagnostic accuracy of PlGF for prediction of MVM was calculated. RESULTS: 130 fetuses met inclusion criteria. Compared to normal PlGF (n = 65), pregnancies with low PlGF (n = 65) were associated with an estimated fetal weight < 5th centile (73.8% (48) vs 53% (35), respectively, p = 0.01), abnormal uterine, umbilical and MCA Dopplers (p = 0.001 for all), fetal demise (18.8% (12) vs 0% respectively, p = 0.01) and preterm delivery (100% (65) vs 39% (59), respectively, p < 0.001) . Low PlGF had a 70.1% (58.6-80.0) sensitivity and a 79.6% (64.7-90.2) specificity for identifying MVM, with an AUC of 0.73 (0.63-0.84). Positive and negative predictive values were 85.7% (76.8-91.2) and 60.3% (51.2-68.9), respectively. PlGF outperformed other parameters of placental FGR (uterine, umbilical artery, middle cerebral artery and abdominal circumference < 5th centile), in isolation and when combined. CONCLUSION: PlGF is a useful tool to aid in the diagnosis of placental FGR secondary to MVM.

Categorization of lung mesenchymal cells in development and fibrosis.

Pulmonary mesenchymal cells are critical players in both the mouse and human during lung development and disease states. They are increasingly recognized as highly heterogeneous, but there is no consensus on subpopulations or discriminative markers for each subtype. We completed scRNA-seq analysis of mesenchymal cells from the embryonic, postnatal, adult and aged fibrotic lungs of mice and humans. We consistently identified and delineated the transcriptome of lipofibroblasts, myofibroblasts, smooth muscle cells, pericytes, mesothelial cells, and a novel population characterized by Ebf1 expression. Subtype selective transcription factors and putative divergence of the clusters during development were described. Comparative analysis revealed orthologous subpopulations with conserved transcriptomic signatures in murine and human lung mesenchymal cells. All mesenchymal subpopulations contributed to matrix gene expression in fibrosis. This analysis would enhance our understanding of mesenchymal cell heterogeneity in lung development, homeostasis and fibrotic disease conditions.

Antibody-mediated depletion of CCR10+EphA3+ cells ameliorates fibrosis in IPF.

Idiopathic pulmonary fibrosis (IPF) is characterized by aberrant repair that diminishes lung function via mechanisms that remain poorly understood. CC chemokine receptor (CCR10) and its ligand CCL28 were both elevated in IPF compared with normal donors. CCR10 was highly expressed by various cells from IPF lungs, most notably stage-specific embryonic antigen-4-positive mesenchymal progenitor cells (MPCs). In vitro, CCL28 promoted the proliferation of CCR10+ MPCs while CRISPR/Cas9-mediated targeting of CCR10 resulted in the death of MPCs. Following the intravenous injection of various cells from IPF lungs into immunodeficient (NOD/SCID-γ, NSG) mice, human CCR10+ cells initiated and maintained fibrosis in NSG mice. Eph receptor A3 (EphA3) was among the highest expressed receptor tyrosine kinases detected on IPF CCR10+ cells. Ifabotuzumab-targeted killing of EphA3+ cells significantly reduced the numbers of CCR10+ cells and ameliorated pulmonary fibrosis in humanized NSG mice. Thus, human CCR10+ cells promote pulmonary fibrosis, and EphA3 mAb-directed elimination of these cells inhibits lung fibrosis.

Differential Responses to Targeting Matrix Metalloproteinase 9 in Idiopathic Pulmonary Fibrosis.

Rationale: Aberrant lung remodeling in idiopathic pulmonary fibrosis (IPF) is characterized by elevated MMP9 (matrix metalloproteinase 9) expression, but the precise role of this matrix metalloproteinase in this disease has yet to be fully elucidated.Objectives: To evaluate antifibrotic effects of MMP9 inhibition on IPF.Methods: Quantitative genomic, proteomic, and functional analyses both in vitro and in vivo were used to determine MMP9 expression in IPF cells and the effects of MMP9 inhibition on profibrotic mechanisms.Measurements and Main Results: In the present study, we demonstrate that MMP9 expression was increased in airway basal cell (ABC)-like cells from IPF lungs compared with ABC cells from normal lungs. The inhibition of MMP9 activity with an anti-MMP9 antibody, andecaliximab, blocked TGF-ß1 (transforming growth factor ß1)-induced Smad2 phosphorylation. However, in a subset of cells from patients with IPF, TGF-ß1 activation in their ABC-like cells was unaffected or enhanced by MMP9 blockade (i.e., nonresponders). Further analysis of nonresponder ABC-like cells treated with andecaliximab revealed an association with type 1 IFN expression, and the addition of IFNα to these cells modulated both MMP9 expression and TGF-ß1 activation. Finally, the inhibition of MMP9 ameliorated pulmonary fibrosis induced by responder lung cells but not a nonresponder in a humanized immunodeficient mouse model of IPF.Conclusions: Together, these data demonstrate that MMP9 regulates the activation of ABC-like cells in IPF and that targeting this MMP might be beneficial to a subset of patients with IPF who show sufficient expression of type 1 IFNs.

High-speed video microscopy and numerical modeling of bubble dynamics near a surface of urinary stone.

Ultra-high-speed video microscopy and numerical modeling were used to assess the dynamics of microbubbles at the surface of urinary stones. Lipid-shell microbubbles designed to accumulate on stone surfaces were driven by bursts of ultrasound in the sub-MHz range with pressure amplitudes on the order of 1 MPa. Microbubbles were observed to undergo repeated cycles of expansion and violent collapse. At maximum expansion, the microbubbles' cross-section resembled an ellipse truncated by the stone. Approximating the bubble shape as an oblate spheroid, this study modeled the collapse by solving the multicomponent Euler equations with a two-dimensional-axisymmetric code with adaptive mesh refinement for fine resolution of the gas-liquid interface. Modeled bubble collapse and high-speed video microscopy showed a distinctive circumferential pinching during the collapse. In the numerical model, this pinching was associated with bidirectional microjetting normal to the rigid surface and toroidal collapse of the bubble. Modeled pressure spikes had amplitudes two-to-three orders of magnitude greater than that of the driving wave. Micro-computed tomography was used to study surface erosion and formation of microcracks from the action of microbubbles. This study suggests that engineered microbubbles enable stone-treatment modalities with driving pressures significantly lower than those required without the microbubbles.

Transcriptional and functional diversity of human macrophage repolarization.

BACKGROUND: Macrophage plasticity allows cells to adopt different phenotypes, a property with important implications in disorders such as cystic fibrosis (CF) and asthma. OBJECTIVE: We sought to examine the transcriptional and functional significance of macrophage repolarization from an M1 to an M2 phenotype and assess the role of a common human genetic disorder (CF) and a prototypical allergic disease (asthma) in this transformation. METHODS: Monocyte-derived macrophages were collected from healthy subjects and patients with CF and polarized to an M2 state by using IL-4, IL-10, glucocorticoids, apoptotic PMNs, or azithromycin. We performed transcriptional profiling and pathway analysis for each stimulus. We assessed the ability of M2-repolarized macrophages to respond to LPS rechallenge and clear apoptotic neutrophils and used murine models to determine conserved functional responses to IL-4 and IL-10. We investigated whether M2 signatures were associated with alveolar macrophage phenotypes in asthmatic patients. RESULTS: We found that macrophages exhibit highly diverse responses to distinct M2-polarizing stimuli. Specifically, IL-10 activated proinflammatory pathways and abrogated LPS tolerance, allowing rapid restoration of LPS responsiveness. In contrast, IL-4 enhanced LPS tolerance, dampening proinflammatory responses after repeat LPS challenge. A common theme observed across all M2 stimuli was suppression of interferon-associated pathways. We found that CF macrophages had intact reparative and transcriptional responses, suggesting that macrophage contributions to CF-related lung disease are primarily shaped by their environment. Finally, we leveraged in vitro-derived signatures to show that allergen provocation induces distinct M2 state transcriptional patterns in alveolar macrophages. CONCLUSION: Our findings highlight the diversity of macrophage polarization, attribute functional consequences to different M2 stimuli, and provide a framework to phenotype macrophages in disease states.

Macrophage MMP10 Regulates TLR7-Mediated Tolerance.

Using an in vivo model of tolerance to TLR7-induced skin inflammation, we found a critical role for macrophage-derived MMP10 in mediating immune hypo-responsiveness. Cutaneous exposure to Imiquimod (IMQ), a TLR7 agonist, induced acute expression of pro-inflammatory factors (IL1ß, IL6, CXCL1) and neutrophil influx equally in both wildtype and Mmp10-/- mice. However, whereas subsequent exposure (11 and 12 days later) to IMQ led to marked abrogation of pro-inflammatory factor expression in wildtype mice, Mmp10-/- mice responded similarly as they did to the first application. In addition, the second exposure led to increased expression of negative regulators of TLR signaling (TNFAIP3, IRAK3) and immunosuppressive cytokines (IL10, TGFß1) in wildtype mice but not in Mmp10-/- mice. In vitro studies demonstrated that prior exposure of IMQ to bone marrow-derived macrophages (BMDM) made wildtype cells refractory to subsequent stimulation but did not for Mmp10-/- macrophages. These findings expand the critical roles MMP10 plays in controlling macrophage activation to indicate that the development of immune tolerance to TLR7 ligand is dependent on this macrophage-derived proteinase.

Matrix metalloproteinase-10 deficiency delays atherosclerosis progression and plaque calcification.

BACKGROUND AND AIMS: Matrix metalloproteinases (MMPs) have been implicated in atherosclerosis and vascular calcification. Among them, we reported that MMP10 is present in human atheroma, associated with atherosclerosis. However, it remains unclear whether MMP10 is involved in atherogenesis and vascular calcification. METHODS: MMP10 was measured in serum from patients with subclinical atherosclerosis and analyzed in carotid endarterectomies by immunostaining. ApoE-deficient mice (Apoe-/-) were crossed to MMP10-deficient (Mmp10-/-) mice and followed up to 20 months. Plaque area and composition were assessed by histology and immunohistochemistry. Inflammatory markers were measured in atherosclerotic plaques by RT-qPCR, and leukocyte subpopulations were analyzed by flow cytometry. In vitro calcification assays were performed in aortic vascular smooth muscle cells (VSMC). RESULTS: MMP10 serum levels were associated with coronary calcification in subjects with subclinical atherosclerosis. Immunostaining revealed MMP10 expression in human atheromas, spatially associated with calcification areas, and complicated plaques released higher amounts of MMP10 than non-diseased segments. Interestingly, vascular MMP10 expression was confined to the atherosclerotic lesion in Apoe-/- mice, and Apoe-/-Mmp10-/- showed a substantial reduction in atherosclerotic lesion size, macrophage content and plaque calcification. Reduced local and systemic inflammatory markers could be demonstrated in Apoe-/-Mmp10-/- by gene expression and flow cytometry analysis. Calcium phosphate deposition and vascular calcification markers were downregulated in VSMC from Apoe-/-Mmp10-/- mice. CONCLUSIONS: Delayed plaque progression and altered cellular composition in the absence of MMP10 suggests that MMP10 plays a role in atherosclerosis, favoring inflammation, development and complication of the plaque.