Octave-spanning mid-infrared femtosecond OPA in a ZnGeP2 pumped by a 2.4†µm Cr:ZnSe chirped-pulse amplifier.

We report on the highly efficient, octave-spanning mid-infrared (mid-IR) optical parametric amplification (OPA) in a ZnGeP2 (ZGP) crystal, pumped by a 1 kHz, 2.4 µm, 250 fs Cr:ZnSe chirped-pulse amplifier. The full spectral coverage of 3-10 µm with the amplified signal and idler beams is demonstrated. The signal beam in the range of ∼3 - 5 µm is produced by either white light generation (WLG) in YAG or optical parametric generation (OPG) in ZGP using the common 2.4 µm pump laser. We demonstrate the pump to signal and idler combined conversion efficiency of 23% and the pulse energy of up to 130 µJ with ∼2 µJ OPG seeding, while we obtain the efficiency of 10% and the pulse energy of 55 µJ with ∼0.2 µJ WLG seeding. The OPA output energy is limited by the available pump pulse energy (0.55 mJ at ZGP crystal) and therefore further energy scaling is feasible with multi-stage OPA and higher pump pulse energy. The autocorrelation measurements based on random quasi-phase matching show that the signal pulse durations are ∼318 fs and ∼330 fs with WLG and OPG seeding, respectively. In addition, we show the spectrally filtered 30 µJ OPA output at 4.15 µm suitable for seeding a Fe:ZnSe amplifier. Our ultrabroadband femtosecond mid-IR source is attractive for various applications, such as strong-field interactions, dielectric laser electron acceleration, molecular spectroscopy, and medical surgery.

Vimentin intermediate filament assembly regulates fibroblast invasion in fibrogenic lung injury.

Idiopathic pulmonary fibrosis (IPF) is a progressive disease, with a median survival of 3-5 years following diagnosis. Lung remodeling by invasive fibroblasts is a hallmark of IPF. In this study, we demonstrate that inhibition of vimentin intermediate filaments (VimIFs) decreases the invasiveness of IPF fibroblasts and confers protection against fibrosis in a murine model of experimental lung injury. Increased expression and organization of VimIFs contribute to the invasive property of IPF fibroblasts in connection with deficient cellular autophagy. Blocking VimIF assembly by pharmacologic and genetic means also increases autophagic clearance of collagen type I. Furthermore, inhibition of expression of collagen type I by siRNA decreased invasiveness of fibroblasts. In a bleomycin injury model, enhancing autophagy in fibroblasts by an inhibitor of VimIF assembly, withaferin A (WFA), protected from fibrotic lung injury. Additionally, in 3D lung organoids, or pulmospheres, from patients with IPF, WFA reduced the invasiveness of lung fibroblasts in the majority of subjects tested. These studies provide insights into the functional role of vimentin, which regulates autophagy and restricts the invasiveness of lung fibroblasts.

Low-dose cadmium exposure induces peribronchiolar fibrosis through site-specific phosphorylation of vimentin.

Exposure to cadmium (Cd) has been associated with development of chronic obstructive lung disease (COPD). The mechanisms and signaling pathways whereby Cd causes pathological peribronchiolar fibrosis, airway remodeling, and subsequent airflow obstruction remain unclear. We aimed to evaluate whether low-dose Cd exposure induces vimentin phosphorylation and Yes-associated protein 1 (YAP1) activation leading to peribronchiolar fibrosis and subsequent airway remodeling. Our data demonstrate that Cd induces myofibroblast differentiation and extracellular matrix (ECM) deposition around small (<2 mm in diameter) airways. Upon Cd exposure, α-smooth muscle actin (α-SMA) expression and the production of ECM proteins, including fibronectin and collagen-1, are markedly induced in primary human lung fibroblasts. Cd induces Smad2/3 activation and the translocation of both Smad2/3 and Yes-associated protein 1 (YAP1) into the nucleus. In parallel, Cd induces AKT and cdc2 phosphorylation and downstream vimentin phosphorylation at Ser39 and Ser55, respectively. AKT and cdc2 inhibitors block Cd-induced vimentin fragmentation and secretion in association with inhibition of α-SMA expression, ECM deposition, and collagen secretion. Furthermore, vimentin silencing abrogates Cd-induced α-SMA expression and decreases ECM production. Vimentin-deficient mice are protected from Cd-induced peribronchiolar fibrosis and remodeling. These findings identify two specific sites on vimentin that are phosphorylated by Cd and highlight the functional significance of vimentin phosphorylation in YAP1/Smad3 signaling that mediates Cd-induced peribronchiolar fibrosis and airway remodeling.

Heme oxygenase-1-mediated autophagy protects against pulmonary endothelial cell death and development of emphysema in cadmium-treated mice.

Pulmonary exposure to cadmium, a major component of cigarette smoke, has a dramatic impact on lung function and the development of emphysema. Cigarette smoke exposure induces heme oxygenase-1 (HO-1), a cytoprotective enzyme. In this study, we employed a truncated mouse model of emphysema by intratracheal instillation of cadmium (CdCl2) solution (0.025% per 1 mg/kg body wt) in HO-1(+/+), HO-1(-/-), and overexpressing humanized HO-1 bacterial artificial chromosome (hHO-1BAC) mice. We evaluated the role of HO-1 in cadmium-induced emphysema in mice by analyzing histopathology, micro-computed tomography scans, and lung function tests. CdCl2-exposed HO-1(-/-) mice exhibited more severe emphysema compared with HO-1(+/+) or hHO-1BAC mice. Loss of pulmonary endothelial cells (PECs) from the alveolar capillary membrane is recognized to be a target in emphysema. PECs from HO-1(+/+), HO-1(-/-), and hHO-1BAC were employed to define the underlying molecular mechanism for the protection from emphysema by HO-1. Electron microscopy, expression of autophagic markers (microtubule-associated protein 1B-light chain 3 II, autophagy protein 5, and Beclin1) and apoptotic marker (cleaved caspase 3) suggested induction of autophagy and apoptosis in PECs after CdCl2 treatment. CdCl2-treated HO-1(-/-) PECs exhibited downregulation of autophagic markers and significantly increased cleaved caspase 3 expression and activity (∼4-fold higher). Moreover, hHO-1BAC PECs demonstrated upregulated autophagy and absence of cleaved caspase 3 expression or activity. Pretreatment of HO-1(+/+) PECs with rapamycin induced autophagy and resulted in reduced cell death upon cadmium treatment. Induction of autophagy following CdCl2 treatment was found to be protective from apoptotic cell death. HO-1 induced protective autophagy in PECs and mitigated cadmium-induced emphysema.

A histological evaluation and in vivo assessment of intratumoral near infrared photothermal nanotherapy-induced tumor regression.

PURPOSE: Nanoparticle (NP)-enabled near infrared (NIR) photothermal therapy has realized limited success in in vivo studies as a potential localized cancer therapy. This is primarily due to a lack of successful methods that can prevent NP uptake by the reticuloendothelial system, especially the liver and kidney, and deliver sufficient quantities of intravenously injected NPs to the tumor site. Histological evaluation of photothermal therapy-induced tumor regression is also neglected in the current literature. This report demonstrates and histologically evaluates the in vivo potential of NIR photothermal therapy by circumventing the challenges of intravenous NP delivery and tumor targeting found in other photothermal therapy studies. METHODS: Subcutaneous Cal 27 squamous cell carcinoma xenografts received photothermal nanotherapy treatments, radial injections of polyethylene glycol (PEG)-ylated gold nanorods and one NIR 785 nm laser irradiation for 10 minutes at 9.5 W/cm(2). Tumor response was measured for 10-15 days, gross changes in tumor size were evaluated, and the remaining tumors or scar tissues were excised and histologically analyzed. RESULTS: The single treatment of intratumoral nanorod injections followed by a 10 minute NIR laser treatment also known as photothermal nanotherapy, resulted in ~100% tumor regression in ~90% of treated tumors, which was statistically significant in a comparison to the average of all three control groups over time (P<0.01). CONCLUSION: Photothermal nanotherapy, or intratumoral nanorod injections followed by NIR laser irradiation of tumors and tumor margins, demonstrate the potential of NIR photothermal therapy as a viable localized treatment approach for primary and early stage tumors, and prevents NP uptake by the reticuloendothelial system.

Limitations of Adenoviral Vector-Mediated Delivery of Gold Nanoparticles to Tumors for Hyperthermia Induction.

Novel combinatorial treatment strategies are desired to achieve tumor eradication. In this regard, nanotechnology and gene therapy hold the potential to expand the available tumor treatment options. In particular, gold nanoparticles (AuNPs) have been utilized for hyperthermic tumor cell ablation. Similarly, adenoviral (Ad) vectors have been utilized for targeting, imaging, and cancer gene therapy. Thus, to combine AuNP-mediated hyperthermia with Ad vector-based gene therapy, we have previously coupled AuNPs to Ad vectors. Herein we tested the capability of these AuNP-coupled Ad vectors for hyperthermic tumor cell ablation. Towards this end, we compared absorption characteristics of different sized AuNPs and determined that in our system 20 nm diameter AuNPs are suitable for laser induced hyperthermic tumor cell killing. In addition, we observed that AuNPs outside and inside the cell contribute differentially towards hyperthermia induction. Unfortunately, due to the limitation of delivery of required amounts of AuNPs to cells, we observed that AuNP-coupled Ad vectors are unable to kill tumor cells via hyperthermia. However, with future technological advances, it may become possible to realize the potential of the multifunctional AuNP-coupled Ad vector system for simultaneous targeting, imaging, and combined hyperthermia and gene therapy of tumors.