In the epidermis, remodelling of Connexin43 is a key event in wound closure. However, controversy between the role of connexin channel and non-channel functions exist. We compared the impact of SiRNA targeted to Connexin43 and the connexin mimetic peptide Gap27 on scrape wound closure rates and hemichannel signalling in adult keratinocytes (AK) and fibroblasts sourced from juvenile foreskin (JFF), human neonatal fibroblasts (HNDF) and adult dermal tissue (ADF). The impact of these agents, following 24 h exposure, on GJA1 (encoding Connexin43), Ki67 and TGF-β1 gene expression, and Connexin43 and pSmad3 protein expression levels, were examined by qPCR and Western Blot respectively. In all cell types Gap27 (100 nM–100 μM) attenuated hemichannel activity. In AK and JFF cells, Gap27 (100 nM–100 μM) enhanced scrape wound closure rates by ~50% but did not influence movement in HNDF or ADF cells. In both JF and AK cells, exposure to Gap27 for 24 h reduced the level of Cx43 protein expression but did not affect the level in ADF and HNDF cells. Connexin43-SiRNA enhanced scrape wound closure in all the cell types under investigation. In HDNF and ADF, Connexin43-SiRNA enhanced cell proliferation rates, with enhanced proliferation also observed following exposure of HDNF to Gap27. By contrast, in JFF and AK cells no changes in proliferation occurred. In JFF cells, Connexin43-SiRNA enhanced TGF-β1 levels and in JFF and ADF cells both Connexin43-SiRNA and Gap27 enhanced pSmad3 protein expression levels. We conclude that Connexin43 signalling plays an important role in cell migration in keratinocytes and foreskin derived fibroblasts, however, different pathways are evoked and in dermal derived adult and neonatal fibroblasts, inhibition of Connexin43 signalling plays a more significant role in regulating cell proliferation than cell migration.

Dysregulation of Connexin (CX) expression and function is associated with a range of chronic inflammatory conditions including psoriasis and nonhealing wounds. To mimic a proinflammatory environment, HaCaT cells, a model human keratinocyte cell line, were challenged with 10 µg/ml peptidoglycan (PGN) isolated from Staphylococcus aureus for 15 min to 24 hr in the presence or absence of CX blockers and/or following CX26, CX43, PANX1 and TLR2 small interfering RNA (siRNA) knockdown (KD). Expression levels of IL‐6, IL‐8, CX26, CX43, PANX1, TLR2 and Ki67 were assessed by quantitative real‐time polymerase chain reaction, western blot analysis and/or immunocytochemistry. Nuclear factor kappa β (NF‐κβ) was blocked with BAY 11‐7082, CX‐channel function was determined by adenosine 5′‐triphosphate (ATP) release assays. Enzyme‐linked immunosorbent assay monitored IL6 release following PGN challenge in the presence or absence of siRNA or blockers of CX or purinergic signalling. Exposure to PGN induced IL‐6, IL‐8, CX26 and TLR2 gene expression but it did not influence CX43, PANX1 or Ki67 messenger RNA expression levels. CX43 protein levels were reduced following 24 hr PGN exposure. PGN‐induced CX26 and IL‐6 expression were also aborted by TLR2‐KD and inhibition of NF‐κβ. ATP and IL‐6 release were stimulated following 15 min and 1–24 hr challenge with PGN, respectively. Release of both agents was inhibited by coincubation with CX‐channel blockers, CX26‐, CX43‐ and TLR2‐KD. The IL‐6 response was also reduced by purinergic blockers. CX‐signalling plays a role in the innate immune response in the epidermis. PGN is detected by TLR2, which via NF‐κβ, directly activates CX26 and IL‐6 expression. CX43 and CX26 maintain proinflammatory signalling by permitting ATP release, however, PANX1 does not participate.

Epithelial tissues line the lumen of tracts and ducts connecting to the external environment. They are critical in forming an interface between the internal and external environment and, following assault from environmental factors and pathogens, they must rapidly repair to maintain cellular homeostasis. These tissue networks, that range from a single cell layer, such as in airway epithelium, to highly stratified and differentiated epithelial surfaces, such as the epidermis, are held together by a junctional nexus of proteins including adherens, tight and gap junctions, often forming unique and localised communication compartments activated for localised tissue repair. This review focuses on the dynamic changes that occur in connexins, the constituent proteins of the intercellular gap junction channel, during wound-healing processes and in localised inflammation, with an emphasis on the lung and skin. Current developments in targeting connexins as corrective therapies to improve wound closure and resolve localised inflammation are also discussed. Finally, we consider the emergence of the zebrafish as a concerted whole-animal model to study, visualise and track the events of wound repair and regeneration in real-time living model systems.

Epithelial tissue responds rapidly to environmental triggers and is constantly renewed. This tissue is also highly accessible for therapeutic targeting. This review highlights the role of connexin mediated communication in avascular epithelial tissue. These proteins form communication conduits with the extracellular space (hemichannels) and between neighboring cells (gap junctions). Regulated exchange of small metabolites less than 1kDa aide the co-ordination of cellular activities and in spatial communication compartments segregating tissue networks. Dysregulation of connexin expression and function has profound impact on physiological processes in epithelial tissue including wound healing. Connexin 26, one of the smallest connexins, is expressed in diverse epithelial tissue and mutations in this protein are associated with hearing loss, skin and eye conditions of differing severity. The functional consequences of dysregulated connexin activity is discussed and the development of connexin targeted therapeutic strategies highlighted.

Peroperative antegrade colonic lavage is often performed before primary anastomosis in emergency colonic surgery. The influence of colonic lavage on bacterial translocation from the obstructed colon was determined. Forty female Wistar rats were studied in four groups: (1) control; (2) non-obstructed with lavage; (3) obstructed; and (4) obstructed with lavage. Ligature obstruction of the rectum was performed in groups 3 and 4. Some 4 days later 35S-radiolabelled Escherichia coli was inoculated into the colon of all animals. Groups 2 and 4 underwent colonic lavage. Lavage in the group 4 animals with left-sided colonic obstruction significantly increased the levels of E. coli in regional nodes, liver, spleen, lung, kidney and blood (as assessed by organ culture and scintillation counting) compared with those in groups 1, 2 and 3 (P < 0.05). These results suggest that peroperative lavage of the obstructed colon significantly increases the level of bacterial translocation.

Impaired wound healing and ulceration caused by diabetes mellitus, is a significant healthcare burden, markedly impairs quality of life for patients, and is the major cause of amputation worldwide. Current experimental approaches used to investigate the complex wound healing process often involve cultures of fibroblasts and/or keratinocytes , which can be limited in terms of complexity and capacity, or utilisation of rodent models in which the mechanisms of wound repair differ substantively from that in humans. However, advances in tissue engineering, and the discovery of strategies to reprogramme adult somatic cells to pluripotency, has led to the possibility of developing models of human skin on a large scale. Generation of induced pluripotent stem cells (iPSCs) from tissues donated by diabetic patients allows the (epi)genetic background of this disease to be studied, and the ability to differentiate iPSCs to multiple cell types found within skin may facilitate the development of more complex skin models; these advances offer key opportunities for improving modelling of wound healing in diabetes, and the development of effective therapeutics for treatment of chronic wounds.

Background: Psoriasis, a chronic inflammatory disease affecting 2–3% of the population, is characterised by epidermal hyperplasia, a sustained pro-inflammatory immune response and is primarily a T-cell driven disease. Previous work determined that Connexin26 is upregulated in psoriatic tissue. This study extends these findings. Methods: Biopsies spanning psoriatic plaque (PP) and non-involved tissue (PN) were compared to normal controls (NN). RNA was isolated and subject to real-time PCR to determine gene expression profiles, including GJB2/CX26, GJB6/CX30 and GJA1/CX43. Protein expression was assessed by immunohistochemistry. Keratinocytes and fibroblasts were isolated and used in 3D organotypic models. The pro-inflammatory status of fibroblasts and 3D cultures was assessed via ELISA and RnD cytokine arrays in the presence or absence of the connexin channel blocker Gap27. Results: Connexin26 expression is dramatically enhanced at both transcriptional and translational level in PP and PN tissue compared to NN (>100x). In contrast, CX43 gene expression is not affected, but the protein is post-translationally modified and accumulates in psoriatic tissue. Fibroblasts isolated from psoriatic patients had a higher inflammatory index than normal fibroblasts and drove normal keratinocytes to adopt a “psoriatic phenotype” in a 3D-organotypic model. Exposure of normal fibroblasts to the pro-inflammatory mediator peptidoglycan, isolated from Staphylococcus aureus enhanced cytokine release, an event protected by Gap27. Conclusion: dysregulation of the connexin26:43 expression profile in psoriatic tissue contributes to an imbalance of cellular events. Inhibition of connexin signalling reduces pro-inflammatory events and may hold therapeutic benefit.

Foams have frequently been used as systems for the delivery of cosmetic and therapeutic molecules; however, there is high variability in the foamability and long-term stability of synthetic foams. The development of pharmaceutical foams that exhibit desirable foaming properties, delivering appropriate amounts of the active pharmaceutical ingredient (API) and that have excellent biocompatibility is of great interest. The production of stable foams is rare in the natural world; however, certain species of frogs have adopted foam production as a means of providing a protective environment for their eggs and larvae from predators and parasites, to prevent desiccation, to control gaseous exchange, to buffer temperature extremes, and to reduce UV damage. These foams show great stability (up to 10 days in tropical environments) and are highly biocompatible due to the sensitive nature of amphibian skin. This work demonstrates for the first time that nests of the túngara frog ( Engystomops pustulosus ) are stable ex situ with useful physiochemical and biocompatible properties and are capable of encapsulating a range of compounds, including antibiotics. These protein foam mixtures share some properties with pharmaceutical foams and may find utility in a range of pharmaceutical applications such as topical drug delivery systems.