Erythrocyte sedimentation rate quantitation in MRL/MpM-lpr/lpr mice

CCM2-deficient endothelial cells undergo a ROCK-dependent reprogramming into senescence-associated secretory phenotype

Cerebral cavernous malformation (CCM) is a cerebrovascular disease in which stacks of dilated haemorrhagic capillaries form focally in the brain. Whether and how defective mechanotransduction, cellular mosaicism and inflammation interplay to sustain the progression of CCM disease is unknown. Here, we reveal that CCM1- and CCM2-silenced endothelial cells expanded in vitro enter into senescence-associated secretory phenotype (SASP) that they use to invade the extracellular matrix and attract surrounding wild-type endothelial and immune cells. Further, we demonstrate that this SASP is driven by the cytoskeletal, molecular and transcriptomic disorders provoked by ROCK dysfunctions. By this, we propose that CCM2 and ROCK could be parts of a scaffold controlling senescence, bringing new insights into the emerging field of the control of ageing by cellular mechanics. These in vitro findings reconcile the known dysregulated traits of CCM2-deficient endothelial cells into a unique endothelial fate. Based on these in vitro results, we propose that a SASP could link the increased ROCK-dependent cell contractility in CCM2-deficient endothelial cells with microenvironment remodelling and long-range chemo-attraction of endothelial and immune cells.

New insights into the functional role of retrotransposon dynamics in mammalian somatic cells

Retrotransposons are genetic elements present across all eukaryotic genomes. While their role in evolution is considered as a potentially beneficial natural source of genetic variation, their activity is classically considered detrimental due to their potentially harmful effects on genome stability. However, studies are increasingly shedding light on the regulatory function and beneficial role of somatic retroelement reactivation in non-pathological contexts. Here, we review recent findings unveiling the regulatory potential of retrotransposons, including their role in noncoding RNA transcription, as modulators of mammalian transcriptional and epigenome landscapes. We also discuss technical challenges in deciphering the multifaceted activity of retrotransposable elements, highlighting an unforeseen central role of this neglected portion of the genome both in early development and in adult life.

Sexual-dimorphism in human immune system aging

Differences in immune function and responses contribute to health- and life-span disparities between sexes. However, the role of sex in immune system aging is not well understood. Here, we characterize peripheral blood mononuclear cells from 172 healthy adults 22-93 years of age using ATAC-seq, RNA-seq, and flow cytometry. These data reveal a shared epigenomic signature of aging including declining naïve T cell and increasing monocyte and cytotoxic cell functions. These changes are greater in magnitude in men and accompanied by a male-specific decline in B-cell specific loci. Age-related epigenomic changes first spike around late-thirties with similar timing and magnitude between sexes, whereas the second spike is earlier and stronger in men. Unexpectedly, genomic differences between sexes increase after age 65, with men having higher innate and pro-inflammatory activity and lower adaptive activity. Impact of age and sex on immune phenotypes can be visualized at https://immune-aging.jax.org to provide insights into future studies.

RP 54745, a potential antirheumatic compound. II. In vivo properties in different animal models

The results obtained with RP 54745, an amino-dithiole-one compound, on stimulated macrophages, revealing inhibition of the hexose monophosphate pathway (HMP), of the exocytosis of lysosomal enzymes and of the production of interleukin-1 (IL-1), by the compound in vitro as well as in vivo, suggested that RP 5475 might influence cells and cytokines implicated in the regulation of the immune system, the disfunctioning of which can lead to inflammatory disorders or autoimmune pathologies. RP 54745 was effective at moderate oral doses (around 5 mg kg-1) in different mouse models of induced arthritis and in the MRL/lpr mice, genetically predisposed to develop an autoimmune pathology including arthritic disorders. The clinical status of the MRL mice, and several of their disturbed biochemical and immunological parameters, improved after a 3-month treatment with RP 54745. This activity of RP 54745 makes it a very attractive antirheumatic compound and a potentially effective treatment in pathologies where IL-1 production is exacerbated.

Effect of (chloro-4-phenyl) thiomethylene bisphosphonic acid (SR 41319) on the autoimmune disease activity in MRL/l mice

MRL - lpr/lpr (MRL/l) mice spontaneously develop an autoimmune pathology including arthritic lesions. SR 41319, a bisphosphonate, having previously shown to be active in in vitro and in vivo models of arthritis, the aim of this study was to search for its possible effect on the pathology of the MRL/l mice. Results showed that SR 41319 reduced the severity of the disease in its early stages and increased mean life span. Further investigation would be necessary to define the effect of the drug during later stages when major changes in immune status occurred.