Obesity-induced dysregulation of skin-resident PPARγ+ Treg cells promotes IL-17A-mediated psoriatic inflammation.

Obesity is a major risk factor for psoriasis, but how obesity disrupts the regulatory mechanisms that keep skin inflammation in check is unclear. Here, we found that skin was enriched with a unique population of CD4+Foxp3+ regulatory T (Treg) cells expressing the nuclear receptor peroxisome proliferation-activated receptor gamma (PPARγ). PPARγ drove a distinctive transcriptional program and functional suppression of IL-17A+ γδ T cell-mediated psoriatic inflammation. Diet-induced obesity, however, resulted in a reduction of PPARγ+ skin Treg cells and a corresponding loss of control over IL-17A+ γδ T cell-mediated inflammation. Mechanistically, PPARγ+ skin Treg cells preferentially took up elevated levels of long-chain free fatty acids in obese mice, which led to cellular lipotoxicity, oxidative stress, and mitochondrial dysfunction. Harnessing the anti-inflammatory properties of these PPARγ+ skin Treg cells could have therapeutic potential for obesity-associated inflammatory skin diseases.

Necroptosis of Lung Epithelial Cells Triggered by Ricin Toxin and Bystander Inflammation.

BACKGROUND/AIMS: The ribosome-inactivating proteins include the biothreat agent, ricin toxin (RT). When inhaled, RT causes near complete destruction of the lung epithelium coincident with a proinflammatory response that includes TNF family cytokines, which are death-inducing ligands. We previously demonstrated that the combination of RT and TNF-related apoptosis inducing ligand (TRAIL) induces caspase-dependent apoptosis, while RT and TNF-α or RT and Fas ligand (FasL) induces cathepsin-dependent cell death in lung epithelial cells. We hypothesize that airway macrophages constitute a major source of cytokines that drive lung epithelial cell death. METHODS: Here, we show that RT-induced apoptosis of the monocytic cell line, U937, leads to the bystander killing of the lung epithelial cell line, A549. U937 cells were treated with ricin. Following this, A549 cells were treated with supernatants from U937 cells and death was measured by WST-1 viability assay. RESULTS: Upon RT-induced U937 cell death, released RT and FasL contributed to A549 cell death. U937 cells also released nuclear protein HMGB1. The release of RT, FasL, and HMGB1 triggered A549 cell necroptosis, rather than cathepsin-dependent killing observed previously with RT and FasL. Reactive oxygen species (ROS) were produced in A549 cells due to HMGB1 ligation of the receptor for advanced glycation end products (RAGE). CONCLUSION: These findings demonstrate the potential for bystander necroptosis of lung epithelial cells during RT toxicosis which may perpetuate or increase the proinflammatory response.

Streamlined intravital imaging approach for long-term monitoring of epithelial tissue dynamics on an inverted confocal microscope.

Understanding normal and aberrant in vivo cell behaviors is necessary to develop clinical interventions to thwart disease initiation and progression. It is therefore critical to optimize imaging approaches that facilitate the observation of cell dynamics in situ, where tissue structure and composition remain unperturbed. The epidermis is the body's outermost barrier as well as the source of the most prevalent human cancers, namely cutaneous skin carcinomas. The accessibility of skin tissue presents a unique opportunity to monitor epithelial and dermal cell behaviors in intact animals using noninvasive intravital microscopy. Nevertheless, this sophisticated imaging approach has primarily been achieved using upright multiphoton microscopes, which represents a significant barrier-for-entry for most investigators. In this study, we present a custom-designed 3D-printed microscope stage insert suitable for use with inverted confocal microscopes that streamlines long-term intravital imaging of ear skin in live transgenic mice. We believe this versatile invention, which may be customized to fit the inverted microscope brand and model of choice, as well as adapted to image additional organ systems, will prove invaluable to the greater scientific research community by significantly enhancing the accessibility of intravital microscopy. This technological advancement is critical to bolster our understanding of live cell dynamics in both normal and disease contexts. SUMMARY: A new tool to simplify intravital imaging using inverted confocal microscopy.

Streamlined Intravital Imaging Approach for Long-Term Monitoring of Epithelial Tissue Dynamics on an Inverted Confocal Microscope.

Understanding normal and aberrant in vivo cell behaviors is necessary to develop clinical interventions to thwart disease initiation and progression. It is therefore critical to optimize imaging approaches that facilitate the observation of cell dynamics in situ, where tissue structure and composition remain unperturbed. The epidermis is the body's outermost barrier, as well as the source of the most prevalent human cancers, namely cutaneous skin carcinomas. The accessibility of skin tissue presents a unique opportunity to monitor epithelial and dermal cell behaviors in intact animals using noninvasive intravital microscopy. Nevertheless, this sophisticated imaging approach has primarily been achieved using upright multiphoton microscopes, which represent a significant barrier for entry for most investigators. This study presents a custom-designed, 3D-printed microscope stage insert suitable for use with inverted confocal microscopes, streamlining the long-term intravital imaging of ear skin in live transgenic mice. We believe this versatile invention, which may be customized to fit the inverted microscope brand and model of choice and adapted to image additional organ systems, will prove invaluable to the greater scientific research community by significantly enhancing the accessibility of intravital microscopy. This technological advancement is critical for bolstering our understanding of live cell dynamics in normal and disease contexts.