Nucleotide-induced PMN adhesion to cultured epithelial cells: possible role of MUC1 mucin

Human isogenic cells of the neurovascular unit exert transcriptomic cell type-specific effects on a blood-brain barrier in vitro model of late-onset Alzheimer disease

BACKGROUND

The function of the blood-brain barrier (BBB) is impaired in late-onset Alzheimer disease (LOAD), but the associated molecular mechanisms, particularly with respect to the high-risk APOE4/4 genotype, are not well understood. For this purpose, we developed a multicellular isogenic model of the neurovascular unit (NVU) based on human induced pluripotent stem cells.

METHODS

The human NVU was modeled in vitro using isogenic co-cultures of astrocytes, brain capillary endothelial-like cells (BCECs), microglia-like cells, neural stem cells (NSCs), and pericytes. Physiological and pathophysiological properties were investigated as well as the influence of each single cell type on the characteristics and function of BCECs. The barriers established by BCECs were analyzed for specific gene transcription using high-throughput quantitative PCR.

RESULTS

Co-cultures were found to tighten the barrier of BCECs and alter its transcriptomic profile under both healthy and disease conditions. In vitro differentiation of brain cell types that constitute the NVU was not affected by the LOAD background. The supportive effect of NSCs on the barrier established by BCECs was diminished under LOAD conditions. Transcriptomes of LOAD BCECs were modulated by different brain cell types. NSCs were found to have the strongest effect on BCEC gene regulation and maintenance of the BBB. Co-cultures showed cell type-specific functional contributions to BBB integrity under healthy and LOAD conditions.

CONCLUSIONS

Cell type-dependent transcriptional effects on LOAD BCECs were identified. Our study suggests that different brain cell types of the NVU have unique roles in maintaining barrier integrity that vary under healthy and LOAD conditions. .

4-Aroyl-3-hydroxy-5-phenyl-1H-pyrrol-2(5H)-ones as N-formyl peptide receptor 1 (FPR1) antagonists

Formyl peptide receptors (FPRs) are expressed on a variety of leukocytes and play important roles in inflammation. Thus, FPR antagonists may represent novel therapeutics for modulating innate immunity and treating inflammatory diseases. Previously, 1H-pyrrol-2(5H)-ones were reported to be potent and competitive FPR1 antagonists. In the present studies, 42 additional 1H-pyrrol-2(5H)-one analogs were evaluated for FPR1 antagonist activity. We identified a number of novel competitive FPR1 antagonists that inhibited N-formylmethionyl-leucyl-phenylalanine (fMLF)-induced intracellular Ca²⁺ mobilization in FPR1-transfected HL60 cells and effectively competed with WKYMVm-FITC for binding to FPR1 in FPR1-transfected RBL cells. The most active pyrroles inhibited human neutrophil Ca²⁺ flux, chemotaxis, and adhesion to human epithelial cells, with the most potent being compounds 14 (4-benzoyl-1-hexyl-3-hydroxy-5-(4-hydroxy-3-methoxyphenyl)-2,5-dihydro-1H-pyrrol-2-one) and 17 (4-benzoyl-5-(2,5-dimethoxyphenyl)-3-hydroxy-1-(2-methoxyethyl)-2,5-dihydro-1H-pyrrol-2-one). In addition, these FPR1 antagonists inhibited fMLF-induced phosphorylation of extracellular signal-regulated kinases (ERK1/2) in FPR1-RBL cells, differentiated HL-60 cells, and human neutrophils. Most of the antagonists were specific for FPR1 and did not inhibit WKYMVM/WKYMVm-induced intracellular Ca²⁺ mobilization in FPR2-HL60 cells, FPR3-HL60 cells, or interleukin 8-induced Ca²⁺ flux in human neutrophils. Moreover, molecular modeling showed that the active pyrroles had a significantly higher degree of similarity with the FPR1 antagonist pharmacophore template as compared to inactive analogs. Thus, the 4-aroyl-3-hydroxy-5-phenyl-1H-pyrrol-2(5H)-one scaffold represents an important backbone for the development of novel FPR1 antagonists and could provide important clues for understanding the molecular structural requirements of FPR1 antagonists.

Role of mucins in the skin during benign and malignant conditions

Skin-related diseases comprise a major health challenge to the practicing physician, and constitute a significant psychological, social and financial burden to the society. Further, skin cancer, especially non-melanoma skin cancer is currently the leading type of malignancy in the Western world. Given the huge burden of skin diseases, there is growing emphasis on understanding their pathophysiology, and towards their early detection. Mucins are high-molecular weight O- and N-linked glycoproteins that have emerged in recent years as important molecules in maintaining health and in promoting or protecting against inflammation and cancer. They have also begun to emerge as highly specific diagnostic and prognostic markers and novel therapeutic targets in several malignant disorders. However, their role in cutaneous pathologies has remained largely obscured. The present review provides the expression patterns and proposed role of mucins in the healthy skin and various benign and malignant skin diseases. The review has immense clinical significance as the availability of highly specific reagents including monoclonal antibodies against mucins makes them extremely attractive targets for specific diagnosis and/or immunotherapy of benign and malignant cutaneous diseases.

Neuronal Control of Skin Function: The Skin as a Neuroimmunoendocrine Organ

This review focuses on the role of the peripheral nervous system in cutaneous biology and disease. During the last few years, a modern concept of an interactive network between cutaneous nerves, the neuroendocrine axis, and the immune system has been established. We learned that neurocutaneous interactions influence a variety of physiological and pathophysiological functions, including cell growth, immunity, inflammation, pruritus, and wound healing. This interaction is mediated by primary afferent as well as autonomic nerves, which release neuromediators and activate specific receptors on many target cells in the skin. A dense network of sensory nerves releases neuropeptides, thereby modulating inflammation, cell growth, and the immune responses in the skin. Neurotrophic factors, in addition to regulating nerve growth, participate in many properties of skin function. The skin expresses a variety of neurohormone receptors coupled to heterotrimeric G proteins that are tightly involved in skin homeostasis and inflammation. This neurohormone-receptor interaction is modulated by endopeptidases, which are able to terminate neuropeptide-induced inflammatory or immune responses. Neuronal proteinase-activated receptors or transient receptor potential ion channels are recently described receptors that may have been important in regulating neurogenic inflammation, pain, and pruritus. Together, a close multidirectional interaction between neuromediators, high-affinity receptors, and regulatory proteases is critically involved to maintain tissue integrity and regulate inflammatory responses in the skin. A deeper understanding of cutaneous neuroimmunoendocrinology may help to develop new strategies for the treatment of several skin diseases.