Inhibition of RANKL- and LPS-induced osteoclast differentiations by novel NF-κB inhibitor DTCM-glutarimide

Immunomodulatory nano-preparations for rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease (AD) caused by the aberrant attack of the immune system on its own joint tissues. Genetic and environmental factors are the main reasons of immune system impairment and high incidence of RA. Although there are medications on the market that lessen disease activity, there is no known cure for RA, and patients are at risk in varying degrees of systemic immunosuppression. By transporting (encapsulating or surface binding) RA-related self-antigens, nucleic acids, immunomodulators, or cytokines, tolerogenic nanoparticles-also known as immunomodulatory nano-preparations-have the potential to gently regulate local immune responses and ultimately induce antigen-specific immune tolerance. We review the recent advances in immunomodulatory nano-preparations for delivering self-antigen or self-antigen plus immunomodulator, simulating apoptotic cell avatars in vivo, acting as artificial antigen-presenting cells, and based on scaffolds and gels, to provide a reference for developing new immunotherapies for RA.

New insights into the regulation of Cystathionine beta synthase (CBS), an enzyme involved in intellectual deficiency in Down syndrome

Down syndrome (DS), the most frequent chromosomic aberration, results from the presence of an extra copy of chromosome 21. The identification of genes which overexpression contributes to intellectual disability (ID) in DS is important to understand the pathophysiological mechanisms involved and develop new pharmacological therapies. In particular, gene dosage of Dual specificity tyrosine phosphorylation Regulated Kinase 1A (DYRK1A) and of Cystathionine beta synthase (CBS) are crucial for cognitive function. As these two enzymes have lately been the main targets for therapeutic research on ID, we sought to decipher the genetic relationship between them. We also used a combination of genetic and drug screenings using a cellular model overexpressing CYS4, the homolog of CBS in Saccharomyces cerevisiae, to get further insights into the molecular mechanisms involved in the regulation of CBS activity. We showed that overexpression of YAK1, the homolog of DYRK1A in yeast, increased CYS4 activity whereas GSK3β was identified as a genetic suppressor of CBS. In addition, analysis of the signaling pathways targeted by the drugs identified through the yeast-based pharmacological screening, and confirmed using human HepG2 cells, emphasized the importance of Akt/GSK3β and NF-κB pathways into the regulation of CBS activity and expression. Taken together, these data provide further understanding into the regulation of CBS and in particular into the genetic relationship between DYRK1A and CBS through the Akt/GSK3β and NF-κB pathways, which should help develop more effective therapies to reduce cognitive deficits in people with DS.

NF-κB: At the Borders of Autoimmunity and Inflammation

The transcription factor NF-κB regulates multiple aspects of innate and adaptive immune functions and serves as a pivotal mediator of inflammatory response. In the first part of this review, we discuss the NF-κB inducers, signaling pathways, and regulators involved in immune homeostasis as well as detail the importance of post-translational regulation by ubiquitination in NF-κB function. We also indicate the stages of central and peripheral tolerance where NF-κB plays a fundamental role. With respect to central tolerance, we detail how NF-κB regulates medullary thymic epithelial cell (mTEC) development, homeostasis, and function. Moreover, we elaborate on its role in the migration of double-positive (DP) thymocytes from the thymic cortex to the medulla. With respect to peripheral tolerance, we outline how NF-κB contributes to the inactivation and destruction of autoreactive T and B lymphocytes as well as the differentiation of CD4⁺-T cell subsets that are implicated in immune tolerance. In the latter half of the review, we describe the contribution of NF-κB to the pathogenesis of autoimmunity and autoinflammation. The recent discovery of mutations involving components of the pathway has both deepened our understanding of autoimmune disease and informed new therapeutic approaches to treat these illnesses.

Cigarette smoke-associated inflammation impairs bone remodeling through NFκB activation

Background

Cigarette smoking constitutes a major lifestyle risk factor for osteoporosis and hip fracture. It is reported to impair the outcome of many clinical procedures, such as wound infection treatment and fracture healing. Importantly, although several studies have already demonstrated the negative correlation between cigarette consume and impaired bone homeostasis, there is still a poor understanding of how does smoking affect bone health, due to the lack of an adequately designed animal model. Our goal was to determine that cigarette smoke exposure impairs the dynamic bone remodeling process through induction of bone resorption and inhibition of bone formation.

Methods

We developed cigarette smoke exposure protocols exposing mice to environmental smoking for 10 days or 3 months to determine acute and chronic smoke exposure effects. We used these models, to demonstrate the effect of smoking exposure on the cellular and molecular changes of bone remodeling and correlate these early alterations with subsequent bone structure changes measured by microCT and pQCT. We examined the bone phenotype alterations in vivo and ex vivo in the acute and chronic smoke exposure mice by measuring bone mineral density and bone histomorphometry. Further, we measured osteoclast and osteoblast differentiation gene expression levels in each group. The function changes of osteoclast or osteoblast were evaluated.

Results

Smoke exposure caused a significant imbalance between bone resorption and bone formation. A 10-day exposure to cigarette smoke sufficiently and effectively induced osteoclast activity, leading to the inhibition of osteoblast differentiation, although it did not immediately alter bone structure as demonstrated in mice exposed to smoke for 3 months. Cigarette smoke exposure also induced DNA-binding activity of nuclear factor kappaB (NFκB) in osteoclasts, which subsequently gave rise to changes in bone remodeling-related gene expression.

Conclusions

Our findings suggest that smoke exposure induces RANKL activation-mediated by NFκB, which could be a “smoke sensor” for bone remodeling.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-02836-z.

A Chemically Modified Curcumin (CMC 2.24) Inhibits Nuclear Factor κB Activation and Inflammatory Bone Loss in Murine Models of LPS-Induced Experimental Periodontitis and Diabetes-Associated Natural Periodontitis

The purpose of this study was to assess the effect of a novel chemically modified curcumin (CMC 2.24) on NF-κB and MAPK signaling and inflammatory cytokine production in two experimental models of periodontal disease in rats. Experimental model I: Periodontitis was induced by repeated injections of LPS into the gingiva (3×/week, 3 weeks); control rats received vehicle injections. CMC 2.24, or the vehicle, was administered by daily oral gavage for 4 weeks. Experimental model II: Diabetes was induced in adult male rats by streptozotocin injection; periodontal breakdown then results as a complication of uncontrolled hyperglycemia. Non-diabetic rats served as controls. CMC 2.24, or the vehicle, was administered by oral gavage daily for 3 weeks to the diabetics. Hemimaxillae and gingival tissues were harvested, and bone loss was assessed radiographically. Gingival tissues were pooled according to the experimental conditions and processed for the analysis of matrix metalloproteinases (MMPs) and bone-resorptive cytokines. Activation of p38 MAPK and NF-κB signaling pathways was assessed by western blot. Both LPS and diabetes induced an inflammatory process in the gingival tissues associated with excessive alveolar bone resorption and increased activation of p65 (NF-κB) and p38 MAPK. In both models, the administration of CMC 2.24 produced a marked reduction of inflammatory cytokines and MMPs in the gingival tissues, decreased bone loss, and decreased activation of p65 (NF-κB) and p38 MAPK. Inhibition of these cell signaling pathways by this novel tri-ketonic curcuminoid (natural curcumin is di-ketonic) may play a role in its therapeutic efficacy in locally and systemically associated periodontitis.

Bu-Shen-Ning-Xin decoction suppresses osteoclastogenesis via increasing dehydroepiandrosterone to prevent postmenopausal osteoporosis

Bu-Shen-Ning-Xin decoction (BSNXD), a traditional Chinese medicine, has been used to prevent and treat age-related diseases such as postmenopausal osteoporosis (PMO) for decades. This study sought to investigate the underlying mechanisms of BSNXD in terms of receptor activation of nuclear factor κB ligand (RANKL)-induced osteoclastogenesis in vitro because of the critical roles of bone resorption in the development and progression of osteoporosis. In mice, serum levels of dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), and 17-β-estradiol (E2) were evaluated with an enzyme immunoassay kit after ovariectomy. Levels of DHEA and DHEAS increased significantly following administration of BSNXD while the level of E2 did not. In addition, tartrate-resistance acid phosphatase staining showed that DHEA profoundly inhibited RANKL-induced osteoclastogenesis in vitro in a dose-dependent manner via estrogen receptor α (ERα) but not via estrogen receptor β or androgen receptors. Cytotoxicity was not detected in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. These data suggest that BSNXD prevents PMO by increasing DHEA via the ERαpathway to suppress osteoclastogenesis.

Modulation of NF-κB Signaling as a Therapeutic Target in Autoimmunity

Autoimmune diseases arise from the loss of tolerance to endogenous self-antigens, resulting in a heterogeneous range of chronic conditions that cause considerable morbidity and mortality worldwide. In Western countries, over 5% of the population is affected by some form of autoimmune disease, with enhanced or inappropriate activation of nuclear factor (NF)-κB implicated in a number of these conditions. Although treatment strategies for autoimmunity have improved significantly in recent years, current therapeutics are still not capable of achieving satisfactory disease management in all patients, and as such, the therapeutic modulation of NF-κB is an attractive target in autoimmunity. To date, no NF-κB inhibitors have progressed to the clinic for the treatment of autoimmunity, but a variety of promising approaches targeting multiple stages of the NF-κB pathway are currently being explored. This review focuses on the current strategies being investigated for the inhibition of the NF-κB pathway in autoimmune diseases and considers potential future strategies for the therapeutic targeting of this crucial transcription factor.