Directing in Vitro Selection towards G-quadruplex-forming Aptamers to Inhibit HMGB1 Pathological Activity.

In the search for novel, effective inhibitors of High-Mobility Group Box1 (HMGB1)-a protein involved in various inflammatory and autoimmune diseases as well as in cancer-we herein discovered a set of anti-HMGB1 G-quadruplex(G4)-forming aptamers by using an in vitro selection procedure applied to a doped library of guanine-rich oligonucleotides. The selected DNA sequences were then studied in a pseudo-physiological buffer mimicking the extracellular medium, where HMGB1 exerts its pathological activity, using spectroscopic, electrophoretic, and chromatographic techniques. All the oligonucleotides proved to fold into monomeric G4s and in some cases also dimeric species, stable at physiological temperature. Remarkably, the protein preferentially recognized the sequences forming dimeric parallel G4 structures, as evidenced by a properly designed chemiluminescent binding assay which also highlighted a good selectivity of these aptamers for HMGB1. Moreover, all aptamers showed anti-HMGB1 activity, inhibiting protein-induced cell migration. The acquired data allowed identifying L12 as the best anti-HMGB1 aptamer, featured by high thermal and enzymatic stability, no toxicity at least up to 5 µM concentration on healthy cells, along with potent anti-HMGB1 activity (IC50 ca. 28 nM) and good binding affinity for the protein, thus indicating it as a very promising lead candidate for in vivo studies.

High mobility group box 1 (HMGB1) as a novel frontier in epileptogenesis: from pathogenesis to therapeutic approaches.

Epilepsy is a serious neurological condition exhibiting complex pathology and deserving of more serious attention. More than 30% of people with epilepsy are not responsive to more than 20 anti-epileptic drugs currently available, reflecting an unmet clinical need for novel therapeutic strategies. Not much is known about the pathogenesis of epilepsy, but evidence indicates that neuroinflammation might contribute to the onset and progression of epilepsy following acquired brain insults. However, the molecular mechanisms underlying these pathophysiological processes are yet to be fully understood. The emerging research suggests that high-mobility group box protein 1 (HMGB1), a DNA-binding protein that is both actively secreted by inflammatory cells and released by necrotic cells, might contribute to the pathogenesis of epilepsy. HMGB1 as an initiator and amplifier of neuroinflammation, and its activation is implicated in the propagation of seizures in animal models. The current review will highlight the potential role of HMGB1 in the pathogenesis of epilepsy, and implications of HMGB1-targeted therapies against epilepsy. HMGB1 in this context is an emerging concept deserving further exploration. Increased understanding of HMGB1 in seizures and epilepsy will pave the way in designing novel and innovative therapeutic strategies that could modify the disease course or prevent its development.

The role of high mobility group box chromosomal protein 1 in rheumatoid arthritis.

High mobility group box chromosomal protein 1 (HMGB1) is a ubiquitous highly conserved single polypeptide in all mammal eukaryotic cells. HMGB1 exists mainly within the nucleus and acts as a DNA chaperone. When passively released from necrotic cells or actively secreted into the extracellular milieu in response to appropriate signal stimulation, HMGB1 binds to related cell signal transduction receptors, such as RAGE, TLR2, TLR4 and TLR9, and becomes a proinflammatory cytokine that participates in the development and progression of many diseases, such as arthritis, acute lung injury, graft rejection immune response, ischaemia reperfusion injury and autoimmune liver damage. Only a small amount of HMGB1 release occurs during apoptosis, which undergoes oxidative modification on Cys106 and delivers tolerogenic signals to suppress immune activity. This review focuses on the important role of HMGB1 in the pathogenesis of RA, mainly manifested as the aberrant expression of HMGB1 in the serum, SF and synovial tissues; overexpression of signal transduction receptors; abnormal regulation of osteoclastogenesis and bone remodelling leading to the destruction of cartilage and bones. Intervention with HMGB1 may ameliorate the pathogenic conditions and attenuate disease progression of RA. Therefore administration of an HMGB1 inhibitor may represent a promising clinical approach for the treatment of RA.