Seeing cilia: imaging modalities for ciliary motion and clinical connections.

The respiratory tract is lined with multiciliated epithelial cells that function to move mucus and trapped particles via the mucociliary transport apparatus. Genetic and acquired ciliopathies result in diminished mucociliary clearance, contributing to disease pathogenesis. Recent innovations in imaging technology have advanced our understanding of ciliary motion in health and disease states. Application of imaging modalities including transmission electron microscopy, high-speed video microscopy, and micron-optical coherence tomography could improve diagnostics and be applied for precision medicine. In this review, we provide an overview of ciliary motion, imaging modalities, and ciliopathic diseases of the respiratory system including primary ciliary dyskinesia, cystic fibrosis, chronic obstructive pulmonary disease, and idiopathic pulmonary fibrosis.

Resident macrophages reprogram toward a developmental state after acute kidney injury.

Acute kidney injury (AKI) is a devastating clinical condition affecting at least two-thirds of critically ill patients, and, among these patients, it is associated with a greater than 60% risk of mortality. Kidney mononuclear phagocytes (MPs) are implicated in pathogenesis and healing in mouse models of AKI and, thus, have been the subject of investigation as potential targets for clinical intervention. We have determined that, after injury, F4/80hi-expressing kidney-resident macrophages (KRMs) are a distinct cellular subpopulation that does not differentiate from nonresident infiltrating MPs. However, if KRMs are depleted using polyinosinic/polycytidylic acid (poly I:C), they can be reconstituted from bone marrow-derived precursors. Further, KRMs lack major histocompatibility complex class II (MHCII) expression before P7 but upregulate it over the next 14 days. This MHCII- KRM phenotype reappears after injury. RNA sequencing shows that injury causes transcriptional reprogramming of KRMs such that they more closely resemble that found at P7. KRMs after injury are also enriched in Wingless-type MMTV integration site family (Wnt) signaling, indicating that a pathway vital for mouse and human kidney development is active. These data indicate that mechanisms involved in kidney development may be functioning after injury in KRMs.

Functional Anatomic Imaging of the Airway Surface.

The airway surface functional microanatomy, including the ciliated airway epithelium and overlying mucus layer, is a critical component of the mucociliary escalator apparatus, an innate immune defense that helps to maintain a clean environment in the respiratory tract. Many genetic and acquired respiratory diseases have underlying pathophysiological mechanisms in which constituents of the airway surface functional microanatomy are defective. For example, in cystic fibrosis, mutations in the cystic fibrosis transmembrane conductance regulator gene, which normally produces a secretory anion channel protein, result in defective anion secretion and consequent dehydrated and acidic mucosal layer overlying the airway epithelium. This thick, viscous mucus results in depressed ciliary beating and delayed mucociliary transport, trapping bacteria and other pathogens, compromising host defenses and ultimately propagating disease progression. Thus, developing tools capable of studying the airway surface microanatomy has been critical to better understanding key pathophysiological mechanisms, and may become useful tools to monitor treatment outcomes. Here, we discuss functional imaging tools to study the airway surface functional microanatomy, and how their application has contributed to an improved understanding of airway disease pathophysiology.

The epithelial sodium channel (ENaC) as a therapeutic target for cystic fibrosis.

Cystic fibrosis (CF) is a monogenic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. CFTR dysfunction is characterized by abnormal mucociliary transport due to a dehydrated airway surface liquid (ASL) and hyperviscous mucus, among other pathologies of host defense. ASL depletion is caused by the absence of CFTR mediated chloride secretion along with continued activity of the epithelial sodium channel (ENaC) activity, which can also be affected by CFTR mediated anion conductance. Therefore, ENaC has been proposed as a therapeutic target to ameliorate ASL dehydration and improve mucus transport. Inhibition of ENaC has been shown to restore ASL hydration and enhance mucociliary transport in induced models of CF lung disease. To date, no therapy inhibiting ENaC has successfully translated to clinical efficacy, in part due to concerns regarding off-target effects, systemic exposure, durability of effect, and adverse effects. Recent efforts have been made to develop novel, rationally designed therapeutics to produce-specific, long-lasting inhibition of ENaC activity in the airways while simultaneously minimizing off target fluid transport effects, systemic exposure and side effects. Such approaches comprise next-generation small molecule direct inhibitors, indirect channel-activating protease inhibitors, synthetic peptide analogs, and oligonucleotide-based therapies. These novel therapeutics represent an exciting step forward in the development of ENaC-directed therapies for CF.

Epigenetic modifiers upregulate MHC II and impede ovarian cancer tumor growth.

Expression of MHC class II pathway proteins in ovarian cancer correlates with prolonged survival. Murine and human ovarian cancer cells were treated with epigenetic modulators - histone deacetylase inhibitors and a DNA methyltransferase inhibitor. mRNA and protein expression of the MHC II pathway were evaluated by qPCR and flow cytometry. Treatment with entinostat and azacytidine of ID8 cells in vitro increased mRNA levels of Cd74, Ciita, and H2-Aa, H2-Eb1. MHC II and CD74 protein expression were increased after treatment with either agent. A dose dependent response in mRNA and protein expression was seen with entinostat. Combination treatment showed higher MHC II protein expression than with single agent treatment. In patient derived xenografts, CIITA, CD74, and MHC II mRNA transcripts were significantly increased after combination treatment. Expression of MHC II on ovarian tumors in MISIIR-Tag mice was increased with both agents relative to control. Combination treatment significantly reduced ID8 tumor growth in immune-competent mice. Epigenetic treatment increases expression of MHC II on ovarian cancer cells and impedes tumor growth. This approach warrants further study in ovarian cancer patients.