Chronic degenerative wounds are often deemed irreparable, directing research efforts to focus predominantly on acute tissue injury regeneration while leaving endogenous repair mechanisms for chronically damaged tissues largely unexplored. In this study, we demonstrate that non-healing, severely degenerated salivary gland tissues can be fundamentally restored through first-line treatment with muscarinic agonists. This approach rescues tissue structure and function, returning it to a homeostatic-like state, and reactivates endogenous regeneration processes to drive new cell expansion that persists for months post-treatment. Furthermore, neuromimetic activation profoundly depletes radiation-induced DNA damage and re-establishes the nerve-acinar relationship, ultimately restoring the tissues physiological capacity to maintain homeostasis, even in the absence of treatment. We show that full recovery of organ function, comparable to uninjured controls, is primarily mediated by the re-differentiation of aberrantly de-differentiated epithelial acinar cells and the restoration of mitochondrial function via a muscarinic-calcium signaling pathway. These findings challenge the prevailing notion that chronic organ degeneration is irreversible and propose a readily testable therapeutic strategy for epithelial restoration with potential applications across a spectrum of chronic injuries.

Corneal lubrication is the most common treatment for relieving the signs and symptoms of dry eye and is considered to be largely palliative with no regenerative functions. Here we challenge this notion by demonstrating that wetting the desiccated cornea of an aqueous-deficient mouse model with the simplest form of lubrication, a saline-based solution, is sufficient to rescue the severely disrupted collagen-rich architecture of the stroma, the largest corneal compartment that is essential to transparency and vision. At the single cell level we show that stromal keratocytes responsible for maintaining stromal integrity are converted from an inflammatory state into unique reparative cell states by lubrication alone, thus revealing the extensive plasticity of these cells and the regenerative function of lubricating the surface. We further show that the generation of a reparative phenotype is due, in part, to disruption of an IL1β autocrine amplification loop promoting chronic inflammation. Thus, our study uncovers the regenerative potential of topical lubrication in dry eye and represents a paradigm shift in our understanding of its therapeutic impact.

Corneal architecture is essential for vision and is greatly perturbed by the absence of tears due to the highly prevalent disorder dry eye. With no regenerative therapies available, pathological alterations of the ocular surface in response to dryness, including persistent epithelial defects and poor wound healing, result in lifelong morbidity. Here, using a mouse model of aqueous-deficient dry eye, we reveal that topical application of the synthetic tear protein lacripep reverses the pathological outcomes of dry eye through restoring the extensive network of corneal nerves that are essential for tear secretion, barrier function, epithelial homeostasis and wound healing. Intriguingly, the restorative effects of lacripep occur despite extensive immune cell infiltration, suggesting tissue reinnervation and regeneration can be achieved under chronic inflammatory conditions. In summary, our data highlight lacripep as a first-in-class regenerative therapy for returning the cornea to a near homeostatic state in individuals who suffer from dry eye.

Autoimmune-mediated dry eye disease is a pathological feature of multiple disorders including Sjögren's syndrome, lupus and rheumatoid arthritis that has a life-long, detrimental impact on vision and overall quality of life. Although late stage disease outcomes such as epithelial barrier dysfunction, reduced corneal innervation and chronic inflammation have been well characterized in both human patients and mouse models, there is little to no understanding of early pathological processes. Moreover, the mechanisms underlying the loss of cornea homeostasis and disease progression are unknown. Here, we utilize the autoimmune regulatory (Aire)-deficient mouse model of autoimmune-mediated dry eye disease in combination with genome wide transcriptomics, high-resolution imaging and atomic force microscopy to reveal a potential extracellular matrix (ECM)-biomechanical-based mechanism driving cellular and morphological changes at early disease onset. Early disease in the Aire-deficient mouse model is associated with a mild reduction in tear production and moderate immune cell infiltration, allowing for interrogation of cellular, molecular and biomechanical changes largely independent of chronic inflammation. Using these tools, we demonstrate for the first time that the emergence of autoimmune-mediated dry eye disease is associated with an alteration in the biomechanical properties of the cornea. We reveal a dramatic disruption of the synthesis and organization of the extracellular matrix as well as degradation of the epithelial basement membrane during early disease. Notably, we provide evidence that the nerve supply to the cornea is severely reduced at early disease stages and that this is independent of basement membrane destruction or significant immune cell infiltration. Furthermore, diseased corneas display spatial heterogeneity in mechanical, structural and compositional changes, with the limbal compartment often exhibiting the opposite response compared to the central cornea. Despite these differences, however, epithelial hyperplasia is apparent in both compartments, possibly driven by increased activation of IL-1R1 and YAP signaling pathways. Thus, we reveal novel perturbations in corneal biomechanics, matrix organization and cell behavior during the early phase of dry eye that may underlie disease development and progression, presenting new potential targets for therapeutic intervention.

Lung cancer is the leading cause of cancer-related death, and 87% of these deaths are directly attributable to smoking. Using three-dimensional cultures of primary human bronchial epithelial cells, we demonstrated that loss of adherens junction protein, epithelial cadherin, and the aberrant interaction of its adherens junction binding partner, p120-catenin (p120ctn), with the cytoplasmic tail of apical mucin-1 (MUC1-CT) represent initiating steps in the epithelial-to-mesenchymal transition. Smoke provoked the rapid nuclear entry of p120ctn in complex with MUC1-CT that was inhibited using the MUC1-CT inhibitory peptides, PMIP and GO-201. Nuclear entry of p120ctn promoted its interaction with transcriptional repressor kaiso and the rapid shuttling of kaiso to the cytoplasm. Nuclear exit of kaiso permitted the up-regulation of oncogenic transcription factors Fos/phospho-Ser32 Fos, FosB, Fra1/phospho-Ser265 Fra1, which was inhibited through suppression of p120ctn's nuclear export using leptomycin-B. These data indicated that smoke-induced nuclear-to-cytoplasmic translocation of kaiso depends on the nuclear import of p120ctn in complex with MUC1-CT and the nuclear export of kaiso in complex with p120ctn. The presence of MUC1-CT/p120ctn and p120ctn/kaiso complexes in lung squamous cell carcinoma and adenocarcinoma specimens from human patients confirms the clinical relevance of these events. Thus, enhancing kaiso's suppressor role of protumor genes by sequestering kaiso in the nucleus of a smoker's airway epithelium may represent a novel approach of treating lung cancer.

Cigarette smoke increases the risk of lung cancer by 20‐fold and accounts for 87% of lung cancer deaths. In the normal airway, heavily O ‐glycosylated mucin‐1 ( MUC1 ) and adherens junctions ( AJs ) establish a structural barrier that protects the airway from infectious, inflammatory and noxious stimuli. Smoke disrupts cell–cell adhesion via its damaging effects on the AJ protein epithelial cadherin (E‐cad). Loss of E‐cad is a major hallmark of epithelial–mesenchymal transition ( EMT ) and has been reported in lung cancer, where it is associated with invasion, metastasis and poor prognosis. Using organotypic cultures of primary human bronchial epithelial ( HBE ) cells treated with smoke‐concentrated medium (Smk), we have demonstrated that E‐cad loss is regulated through the aberrant interaction of its AJ binding partner, p120‐catenin (p120ctn), and the C‐terminus of MUC1 ( MUC1 ‐C). Here, we reported that even before MUC1 ‐C became bound to p120ctn, smoke promoted the generation of a novel 400 kDa glycoform of MUC1 's N ‐terminus ( MUC1 ‐N) differing from the 230 kDa and 150 kDa glycoforms in untreated control cells. The subsequent smoke‐induced, time‐dependent shedding of glycosylated MUC1 ‐N exposed MUC1 ‐C as a putative receptor for interactions with EGFR , Src and p120ctn. Smoke‐induced MUC1 ‐C glycosylation modulated MUC1 ‐C tyrosine phosphorylation ( TyrP ) that was essential for MUC1‐C/p120ctn interaction through dose‐dependent bridging of Src/MUC1‐C/galectin‐3/EGFR signalosomes. Chemical deglycosylation of MUC1 using a mixture of N ‐glycosylation inhibitor tunicamycin and O ‐glycosylation inhibitor benzyl‐ α ‐ GalNAc disrupted the Src/MUC1‐C/galectin‐3/EGFR complexes and thereby abolished smoke‐induced MUC1 ‐C‐ TyrP and MUC1‐C/p120ctn interaction. Similarly, inhibition of smoke‐induced MUC1 ‐N glycosylation using adenoviral shRNA directed against N ‐acetyl‐galactosaminyl transferase‐6 ( GALNT6 , an enzyme that controls the initiating step of O ‐glycosylation) successfully suppressed MUC1‐C/p120ctn interaction, prevented E‐cad degradation and maintained cellular polarity in response to smoke. Thus, GALNT6 shRNA represents a potential therapeutic modality to prevent the initiation of events associated with EMT in the smoker's airway. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.