Therapeutic concentration of lithium stimulates complement C3 production in dendritic cells and microglia via GSK-3 inhibition

Evidence indicates that widely prescribed mood stabilizer, lithium (Li), mediates cellular functions of differentiated monocytic cells, including microglial migration, monocyte-derived dendritic cell (MoDC) differentiation, and amelioration of monocytic malfunctions observed in neuropsychiatric diseases. Here, we surveyed molecules which take major roles in regulating these monocytic cellular functions. MoDCs treated with 1 and 5 mM Li, and microglia separated from Li-treated mice were subjected to microarray-based comprehensive gene expression analyses. Findings were validated using multiple experiments, including quantitative PCR, ELISA and immunostaining studies. Differing effects of Li on the two cell types were observed. Inflammation- and chemotaxis-relevant genes were significantly over-represented among Li-induced genes in MoDCs, whereas no specific category of genes was over-represented in microglia. The third component of complement (C3) was the only gene which was significantly induced by a therapeutic concentration of Li in both MoDCs and microglia. C3 production was increased by Li via GSK-3 inhibition. Li-induced C3 production was seen only in differentiated monocytic cells, but not in circulating monocytes. Our findings highlight a link between Li treatment and C3 production in differentiated monocytic cells, and reveal a regulatory role of GSK-3 in C3 production. Induction of microglial C3 production might be a novel neuroprotective mechanism of Li via regulating interactions between microglia and neurons. GLIA 2015;63:257-270.

Alteration of the EphA2/Ephrin-A signaling axis in psoriatic epidermis

EphA2 is a receptor tyrosine kinase (RTK) that triggers keratinocyte differentiation upon activation and subsequent downregulation by ephrin-A1 ligand. The objective of this study was to determine whether the EphA2/ephrin-A1 signaling axis was altered in psoriasis, an inflammatory skin condition in which keratinocyte differentiation is abnormal. Microarray analysis of skin biopsies from psoriasis patients revealed increased mRNA transcripts for several members of this RTK family in plaques, including the EphA1, EphA2, and EphA4 subtypes prominently expressed by keratinocytes. Of these, EphA2 showed the greatest upregulation, a finding that was confirmed by quantitative reverse-transcriptase-PCR, immunohistochemistry (IHC), and ELISA. In contrast, psoriatic lesions exhibited reduced ephrin-A ligand immunoreactivity. Exposure of primary keratinocytes induced to differentiate in high calcium or a three-dimensional (3D) raft culture of human epidermis to a combination of growth factors and cytokines elevated in psoriasis increased EphA2 mRNA and protein expression while inducing S100A7 and disrupting differentiation. Pharmacological delivery of a soluble ephrin-A1 peptidomimetic ligand led to a reduction in EphA2 expression and ameliorated proliferation and differentiation in raft cultures exposed to EGF and IL-1α. These findings suggest that ephrin-A1-mediated downregulation of EphA2 supports keratinocyte differentiation in the context of cytokine perturbation.

Integrated network analysis of transcriptomic and proteomic data in psoriasis

BACKGROUND

Psoriasis is complex inflammatory skin pathology of autoimmune origin. Several cell types are perturbed in this pathology, and underlying signaling events are complex and still poorly understood.

RESULTS

In order to gain insight into molecular machinery underlying the disease, we conducted a comprehensive meta-analysis of proteomics and transcriptomics of psoriatic lesions from independent studies. Network-based analysis revealed similarities in regulation at both proteomics and transcriptomics level. We identified a group of transcription factors responsible for overexpression of psoriasis genes and a number of previously unknown signaling pathways that may play a role in this process. We also evaluated functional synergy between transcriptomics and proteomics results.

CONCLUSIONS

We developed network-based methodology for integrative analysis of high throughput data sets of different types. Investigation of proteomics and transcriptomics data sets on psoriasis revealed versatility in regulatory machinery underlying pathology and showed complementarities between two levels of cellular organization.