Soluble Decoy Receptor Research Articles

A stable, engineered TL1A ligand co-stimulates T cells via specific binding to DR3

TL1A (TNFSF15) is a TNF superfamily ligand which can bind the TNFRSF member death receptor 3 (DR3) on T cells and the soluble decoy receptor DcR3. Engagement of DR3 on CD4+ or CD8+ effector T cells by TL1A induces downstream signaling, leading to proliferation and an increase in secretion of inflammatory cytokines. We designed a stable recombinant TL1A molecule that (1) displays high monodispersity and stability, (2) displays the ability to activate T cells in vitro and in vivo, and (3) lacks binding to DcR3 while retaining functional activity via DR3. Together these results suggest the TL1A ligand can be amenable to therapeutic development on its own or paired with a tumor-targeting moiety.

Salivary Gene Expression of RANK, RANKL, and OPG in Type 1 Diabetes Mellitus and Periodontal Disease Patients.

The relationship between type 1 diabetes mellitus (T1DM) and periodontal disease may exhibit by the alteration of bone metabolism. However, evidence for this relationship is scarce and inconclusive. Thus, the aims of the present study were to investigate salivary receptor activator of nuclear factor kappa-β (RANK), receptor activator of nuclear factor kappa-β ligand (RANKL), osteoprotegerin (OPG) gene expression and the RANKL:OPG ratio in T1DM and non-T1DM. Secondary objective was to determine the relationships of RANK, RANKL and OPG gene expression to clinical parameters of T1DM and periodontal disease. Twenty patients with T1DM and twenty age-matched non-T1DM were recruited. Clinical periodontal parameters were measured. Total RNA was isolated from non-stimulated saliva, and the relative gene expressions of RANK, RANKL, OPG and RANKL:OPG ratio were determined by quantitative real-time polymerase chain reaction. The T1DM group had significantly higher mean periodontal parameters than the non-T1DM group, while the mean plaque scores of both groups were not significantly different. There was a trend of higher relative gene expression of RANK, RANKL, and the RANKL:OPG ratio and lower expression of OPG in T1DM group but no statistic significant different when compared to non-T1DM. In the T1DM group, RANKL:OPG correlated with the percentage of bleeding sites, whereas RANK, RANKL, and HbA1c levels correlated with pocket depth. Bone metabolisms demonstrating by decreased OPG gene expression and upregulated of RANK, RANKL, RANKL:OPG with higher pocket depth and bleeding in T1DM may play an important role in periodontal destruction in T1DM.

Rilonacept and Other Interleukin-1 Inhibitors in the Treatment of Recurrent Pericarditis.

Pericarditis is the commonest form of pericardial disease. Unfortunately, despite optimal treatment, approximately 15-30% of patients with acute pericarditis have recurrence. Many of these patients are refractory to colchicine, and become corticosteroid-dependent. Recurrent pericarditis severely impairs quality of life, and is associated with significant morbidity. Inflammasome formation and overproduction of interleukin (IL)-1 have been found to drive the systemic inflammatory response in recurrent autoinflammatory pericarditis. Several IL-1 inhibitors have been evaluated for their usefulness as therapeutic options. Rilonacept is a dimeric fusion protein that functions as a soluble decoy receptor that binds to both IL-1α and IL-1β, thereby inhibiting the IL-1 pathway. It is safe and efficacious in the treatment of recurrent pericarditis in the RHAPSODY II and III trials. Anakinra is a recombinant IL-1 receptor antagonist that blocks the action of circulating IL-1α and IL-1β. It has also been shown to be safe and efficacious in the AIRTRIP and IRAP studies. Canakinumab is a selective human monoclonal antibody against IL-1β, and data on its use in recurrent pericarditis is scarce. Several questions regarding IL-1 inhibitor therapy, such as the duration of treatment and the recommended tapering protocols, as well as their use in special populations like pregnant or lactating women, remain unanswered and need to be addressed in future studies.

An ACE2 decoy can be administered by inhalation and potently targets omicron variants of SARS‐CoV‐2

Monoclonal antibodies targeting the SARS‐CoV‐2 spike (S) neutralize infection and are efficacious for the treatment of COVID‐19. However, SARS‐CoV‐2 variants, notably sublineages of B.1.1.529/omicron, have emerged that escape antibodies in clinical use. As an alternative, soluble decoy receptors based on the host entry receptor ACE2 broadly bind and block S from SARS‐CoV‐2 variants and related betacoronaviruses. The high‐affinity and catalytically active decoy sACE22.v2.4‐IgG1 was previously shown to be effective against SARS‐CoV‐2 variants when administered intravenously. Here, inhalation of aerosolized sACE22.v2.4‐IgG1 increased survival and ameliorated lung injury in K18‐hACE2 mice inoculated with P.1/gamma virus. Loss of catalytic activity reduced the decoy's therapeutic efficacy, which was further confirmed by intravenous administration, supporting dual mechanisms of action: direct blocking of S and turnover of ACE2 substrates associated with lung injury and inflammation. Furthermore, sACE22.v2.4‐IgG1 tightly binds and neutralizes BA.1, BA.2, and BA.4/BA.5 omicron and protects K18‐hACE2 mice inoculated with a high dose of BA.1 omicron virus. Overall, the therapeutic potential of sACE22.v2.4‐IgG1 is demonstrated by the inhalation route and broad neutralization potency persists against highly divergent SARS‐CoV‐2 variants.

The Sex-Dependent Role of Myostatin Signaling in Contractures Following Neonatal Brachial Plexus Injury

Purpose: Neonatal brachial plexus injury (NBPI) causes disabling and incurable muscle contractures, arising from impaired longitudinal growth of denervated muscles. This growth impairment is caused by dysregulation of muscle proteostasis characterized by increased proteasome-mediated protein degradation. Myostatin (MSTN), a secreted growth differentiation factor and prominent muscle-specific negative regulator of proteostasis, drives muscle protein degradation. MSTN signaling is thus a possible pathway through which denervation impairs muscle growth and a potential muscle-specific molecular target for preventing contractures. This study uses pharmacologic inhibition of MSTN signaling in a mouse model of NBPI to test the hypothesis that NBPI induces contractures through MSTN-dependent impairment of longitudinal muscle growth. Methods: Unilateral NBPI was generated in postnatal day (P)5 mice. Mice were treated weekly with Dulbecco’s phosphate-buffered saline (DPBS) or ACVR2B-Fc, a soluble inhibitory decoy receptor for MSTN, starting at P4. Mice were sacrificed at P33, whereupon elbow and shoulder range of motion were measured to assess contractures. Brachialis muscles were prepared for microCT assessment of cross-sectional area (CSA) and volume, then processed for sarcomere length measurement as a readout of longitudinal muscle growth. Total protein content in biceps was assessed via Bradford assay. Protein degradation in triceps was quantified via 20S proteasome β1 subunit activity assay. Results: In female mice, myostatin inhibition with ACVR2B-Fc enhanced muscle weight and total protein content of denervated biceps (Figure 1), increased cross-sectional and volumetric growth of denervated brachialis (Figure 2), preserved longitudinal growth in denervated brachialis (Figure 3), and reduced elbow and shoulder contracture severity in the denervated limbs (Figure 4). Analysis of protein dynamics demonstrates the improvements in female denervated muscles were associated with a reduction in proteasome β1 subunit activity (Figure 5). However, no such improvements in denervated muscles occurred in male mice with ACVR2B-Fc. Conversely, myostatin inhibition increased muscle weight, CSA, volume, and total protein content of the normally innervated, contralateral control muscles in both male and female mice (Figures 1 and 2). Conclusion: Our findings reveal MSTN as a driver of impaired muscle growth and contracture formation in female but not male mice. This sex dimorphism lies in the pathophysiology of denervation-induced contractures rather than drug pharmacodynamics, given the sex-independent effects of MSTN inhibition on normally innervated muscle. Future studies must rigorously interrogate the contributions of sex in contracture pathophysiology. Significance: Our discovery identifies MSTN as a signaling target for modulating contractures in females and highlights the overlooked role of sex in the pathophysiology of acquired neuromuscular disorders. Level of Evidence: Not Applicable FDA: The FDA has not cleared the following pharmaceuticals and/or medical devices for the use described in this presentation.

KYMASIN UP Natural Product Inhibits Osteoclastogenesis and Improves Osteoblast Activity by Modulating Src and p38 MAPK.

The imbalance in osteoblast (OB)-dependent bone formation in favor of osteoclast (OC)-dependent bone resorption is the main cause of loss of tissue mineral mass during bone remodeling leading to osteoporosis conditions. Thus, the suppression of OC activity together with the improvement in the OB activity has been proposed as an effective therapy for maintaining bone mass during aging. We tested the new dietary product, KYMASIN UP containing standardized Withania somnifera, Silybum marianum and Trigonella foenum-graecum herbal extracts or the single extracts in in vitro models mimicking osteoclastogenesis (i.e., RAW 264.7 cells treated with RANKL, receptor activator of nuclear factor kappa-Β ligand) and OB differentiation (i.e., C2C12 myoblasts treated with BMP2, bone morphogenetic protein 2). We found that the dietary product reduces RANKL-dependent TRAP (tartrate-resistant acid phosphatase)-positive cells (i.e., OCs) formation and TRAP activity, and down-regulates osteoclastogenic markers by reducing Src (non-receptor tyrosine kinase) and p38 MAPK (mitogen-activated protein kinase) activation. Withania somnifera appears as the main extract responsible for the anti-osteoclastogenic effect of the product. Moreover, KYMASIN UP maintains a physiological release of the soluble decoy receptor for RANKL, OPG (osteoprotegerin), in osteoporotic conditions and increases calcium mineralization in C2C12-derived OBs. Interestingly, KYMASIN UP induces differentiation in human primary OB-like cells derived from osteoporotic subjects. Based on our results, KYMASIN UP or Withania somnifera-based dietary supplements might be suggested to reverse the age-related functional decline of bone tissue by re-balancing the activity of OBs and OCs, thus improving the quality of life in the elderly and reducing social and health-care costs.

Interleukin-18 Binding Protein in Immune Regulation and Autoimmune Diseases.

Natural soluble antagonist and decoy receptor on the surface of the cell membrane are evolving as crucial immune system regulators as these molecules are capable of recognizing, binding, and neutralizing (so-called inhibitors) their targeted ligands. Eventually, these soluble antagonists and decoy receptors terminate signaling by prohibiting ligands from connecting to their receptors on the surface of cell membrane. Interleukin-18 binding protein (IL-18BP) participates in regulating both Th1 and Th2 cytokines. IL-18BP is a soluble neutralizing protein belonging to the immunoglobulin (Ig) superfamily as it harbors a single Ig domain. The Ig domain is essential for its binding to the IL-18 ligand and holds partial homology to the IL-1 receptor 2 (IL-1R2) known as a decoy receptor of IL-1α and IL-1β. IL-18BP was defined as a unique soluble IL-18BP that is distinct from IL-18Rα and IL-18Rβ chain. IL-18BP is encoded by a separated gene, contains 8 exons, and is located at chr.11 q13.4 within the human genome. In this review, we address the difference in the biological activity of IL-18BP isoforms, in the immunity balancing Th1 and Th2 immune response, its critical role in autoimmune diseases, as well as current clinical trials of recombinant IL-18BP (rIL-18BP) or equivalent.

Angiotensin II Induces Aortic Rupture and Dissection in Osteoprotegerin-Deficient Mice.

BackgroundThe biological mechanism of action for osteoprotegerin, a soluble decoy receptor for the receptor activator of nuclear factor‐kappa B ligand in the vascular structure, has not been elucidated. The study aim was to determine if osteoprotegerin affects aortic structural integrity in angiotensin II (Ang II)‐induced hypertension.Methods and ResultsMortality was higher (P<0.0001 by log‐rank test) in 8‐week‐old male homozygotes of osteoprotegerin gene‐knockout mice given subcutaneous administration of Ang II for 28 days, with an incidence of 21% fatal aortic rupture and 23% aortic dissection, than in age‐matched wild‐type mice. Ang II‐infused aorta of wild‐type mice showed that osteoprotegerin immunoreactivity was present with proteoglycan. The absence of osteoprotegerin was associated with decreased medial and adventitial thickness and increased numbers of elastin breaks as well as with increased periostin expression and soluble receptor activator of nuclear factor‐kappa B ligand concentrations. PEGylated human recombinant osteoprotegerin administration decreased all‐cause mortality (P<0.001 by log‐rank test), the incidence of fatal aortic rupture (P=0.08), and aortic dissection (P<0.001) with decreasing numbers of elastin breaks, periostin expressions, and soluble receptor activator of nuclear factor‐kappa B ligand concentrations in Ang II‐infused osteoprotegerin gene‐knockout mice.ConclusionsThese data suggest that osteoprotegerin protects against aortic rupture and dissection in Ang II‐induced hypertension by inhibiting receptor activator of nuclear factor‐kappa B ligand activity and periostin expression.

Structural basis of human IL-18 sequestration by the decoy receptor IL-18 binding protein in inflammation and tumor immunity

Human Interleukin-18 (IL-18) is an omnipresent proinflammatory cytokine of the IL-1 family with central roles in autoimmune and inflammatory diseases and serves as a staple biomarker in the evaluation of inflammation in physiology and disease, including the inflammatory phase of COVID-19. The sequestration of IL-18 by its soluble decoy receptor IL-18-Binding Protein (IL-18BP) is critical to the regulation of IL-18 activity. Since an imbalance in expression and circulating levels of IL-18 is associated with disease, structural insights into how IL-18BP outcompetes binding of IL-18 by its cognate cell-surface receptors are highly desirable; however, the structure of human IL-18BP in complex with IL-18 has been elusive. Here, we elucidate the sequestration mechanism of human IL-18 mediated by IL-18BP based on the crystal structure of the IL-18:IL-18BP complex. These detailed structural snapshots reveal the interaction landscape leading to the ultra-high affinity of IL-18BP toward IL-18 and identify substantial differences with respect to previously characterized complexes of IL-18 with IL-18BP of viral origin. Furthermore, our structure captured a fortuitous higher-order assembly between IL-18 and IL-18BP coordinated by a disulfide-bond distal to the binding surface connecting IL-18 and IL-18BP molecules from different complexes, resulting in a novel tetramer with 2:2 stoichiometry. This tetrapartite assembly was found to restrain IL-18 activity more effectively than the canonical 1:1 complex. Collectively, our findings provide a framework for innovative, structure-driven therapeutic strategies and further functional interrogation of IL-18 in physiology and disease.

Potential mechanisms of osteoprotegerin-induced damage to osteoclast adhesion structures via P2X7R-mediated MAPK signaling.

Osteoprotegerin (OPG) is a negative regulator of osteoclast formation by competing with receptor activator of the nuclear factor-κB (NF-κB) ligand (RANKL) for RANK. OPG is not only a soluble decoy receptor for RANKL, but is also considered as a direct effector of osteoclast functions. However, the mechanismsresponsible for OPG-induced changes to osteoclast bone resorption functionsremain unknown. P2X7R is involved in the process of multi-nucleation and cell fusion. Therefore, in the present study, mitogen-activated protein kinase (MAPK) inhibitors and the RNA interference of purinergic receptor P2X7 (P2X7R) were usedtoexamine the effects of P2X7R-mediated MAPK signaling on changes to osteoclast adhesion structure induced by OPG; for this purpose, western blot analysis and immunofluorescence staining were performed. The results revealed that OPG inhibited osteoclast adhesion-related protein expression, disrupted adhesion protein distribution, and destroyed osteoclast filopodia and lamellipodia structures. The inhibitors partially restored osteoclast adhesion structure, including protein expression, distribution and cell morphology. The absence of P2X7R markedly inhibited osteoclast formation, and subsequent OPG treatment accelerated the damage to adhesion structures. However, P2X7R activation significantly recosvered the phosphorylation of paxillin, vinculin, phosphorylated protein tyrosine kinase 2 and SRC proto-oncogene, non-receptor tyrosine kinase induced by OPG, and their distribution was uniform at the osteoclast periphery. P2X7R silencing suppressed the phosphorylation of MAPK. On the whole, the findings of the present study highlighta key role of P2X7R/MAPK signaling in osteoclast adhesion, and provide a novel therapeutic target for bone disease.

Anti-tumor activity of a recombinant soluble Fzd7 decoy receptor in human gastric and colon cancer cells.

Objective(s):Frizzled-7, the most common receptor of the Wnt signaling pathway, was significantly over-expressed in gastric (GC) and colorectal (CRC) cancers and stimulated tumorigenesis. The extracellular domain of Fzd7 (sFzd7) as a decoy receptor, could competitively bound with ligands and antagonize the interaction between Fzd7 receptors and Wnt ligands. Materials and Methods:We expressed and purified the extracellular region of Fzd7 including cysteine-rich domain (33 aa–185 aa) from Escherichia coli by chromatography. The effect of sFzd7 was evaluated on AGS gastric and SW480 colon cancer cell lines expressing high levels of Fzd7 receptor. Accordingly, cell viability and apoptosis were measured using MTT and flow cytometry assays, respectively. Real-Time PCR determined the relative expression of the β-catenin and cyclin-D1 genes. Results:After three days of treatment with sFzd7, the viability of AGS and SW480 cell lines was decreased in a dose-dependent manner. In addition, sFzd7 at concentrations of 10 and 20 ug/ml increased the rate of apoptosis. Especially at the concentration of 20 ug/ml, the apoptosis rate was remarkably high in AGS (P-value= 0.003) and SW480 cells (P-value= 0.0007). Finally, the expressions of β-catenin (P-value= 0.01) and cyclin-D1 (P-value= 0.02) were obviously decreased in SW480 cells. The same results were obtained in AGS cells, although not statistically significant. Conclusion:sFzd7 decoy receptor inhibits tumor cell progression by attenuating the Wnt pathway through inhibiting Fzd7 receptors and Wnt ligand interaction. Hence, sFzd7 can be proposed as a candidate therapy for GC and CRC cells with high levels of Fzd7 expression.

Soluble Fas ligand, soluble Fas receptor, and decoy receptor 3 as disease biomarkers for clinical applications: A review

&lt;abstract&gt; &lt;p&gt;Soluble Fas ligand (sFasL, sCD95L) and its specific soluble binders, soluble Fas receptor (sFas, sCD95) and decoy receptor 3 (DcR3), have been investigated as possible clinical biomarkers in many serious diseases. The present review aimed to provide an overview of the current state of this medically promising research by extensively examining the relevant literature. The summarized results of the survey are presented after classification into six categories according to the type of targeted disease. To date, the studies have been mainly devoted to the diagnosis of disease severity states and prognosis of treatments about various types of cancers and autoimmune diseases represented by autoimmune lymphoproliferative syndrome and systemic lupus erythematosus, because these important life-threatening or intractable diseases were suggested to be most relevant to the impairment of apoptotic cell death-inducing systems, including the Fas receptor-mediated signaling system, and the mechanisms responsible for their onset. However, various more general inflammation-related diseases, including, but not limited to, other autoimmune and allergic diseases (e.g., rheumatoid arthritis and atopic asthma), infectious diseases (e.g., sepsis and chronic hepatitis), cardiovascular system-specific disorders (e.g., acute coronary syndromes and heart failure) as well as other diseases specific to the renal, hepatic, and respiratory systems, etc., have also been targeted as important fields of research. The data obtained so far demonstrated that sFas, sFasL, and DcR3 possess significant potential in the assessment of various disease states, which can contribute to the development of therapeutic interventions. Although further studies in various relevant fields are essential, it is expected that clinical translation of sFas, sFasL, and DcR3 into practical biomarkers will contribute to effective treatments of a wide variety of diseases.&lt;/p&gt; &lt;/abstract&gt;

Inhibition of central axon regeneration: perspective from chondroitin sulfate proteoglycans in lamprey spinal cord injury.

Inhibition of central axon regeneration: perspective from chondroitin sulfate proteoglycans in lamprey spinal cord injury.

TNF antagonizes CCN1 in apoptosis in esophageal adenocarcinoma.

TNF signaling mostly supports cell growth by activating NFκB and only induces cell death when NFκB activation fails. CCN1 is a matricellular protein that has been reported capable to convert TNF from a pro-survival factor into a stimulus for cell death without interfering with NFκB signaling. In this study, we examined the relationship between CCN1 and TNF in the context of esophageal adenocarcinoma and found that CCN1 did not help TNF to induce cell death when they were together, instead, it inhibited TNF expression, as well as TNF-induced JNK activation and apoptosis. CCN1 induced apoptosis in the cancer cells by itself through upregulation of TRAIL and its death receptors. The presence of TNF significantly lowered CCN1 expression and its capability in apoptosis induction. Furthermore, we found that CCN1 boosted ADAM17-mediated cleavage of TNF receptors through ITGA11 and the soluble decoy receptors generated by this action neutralized TNF activity. Taken together, CCN1 and TNF antagonize each other in esophageal cancer cells.

Osteoprotegerin (OPG) mediates the anti-carcinogenic effects of normal breast fibroblasts and targets cancer stem cells through inhibition of the β-catenin pathway.

Normal breast fibroblasts (NBFs) support and maintain the architecture of the organ, and can also suppress tumorigenesis. However, the mechanisms involved are not fully understood. We have shown here that NBFs suppress breast carcinogenesis through secretion of osteoprotegerin (OPG), a soluble decoy receptor for the Receptor Activator of NF-κB ligand (RANKL). Indeed, NBFs and human recombinant OPG (rOPG), suppressed breast cancer cells proliferation and motility through inhibition of the epithelial-to-mesenchymal transition (EMT) process both in vitro and in vivo. Additionally, rOPG inhibited the IL-6/STAT3 and NF-κB pathways as well as the OPG gene, which turned out to be STAT3-regulated. This was confirmed using denosumab, a RANKL-targeted antibody, which also inhibited NF-κB, down-regulated OPG and repressed EMT in breast cancer cells grown in 2D and 3D. Importantly, both rOPG and denosumab targeted cancer stem cells (CSCs). This was mediated through inhibition of the CSC-related pathway β-catenin. Moreover, rOPG reduced tumor growth and inhibited breast CSC biomarkers in orthotopic humanized breast tumors. Therefore, normal mammary fibroblasts can suppress carcinogenesis through OPG, which constitutes great potential as preventive and/or therapeutic molecule for breast carcinomas.

Anti-interleukin-1 agents for pericarditis: a primer for cardiologists.

Anti-interleukin (IL)-1 agents have been developed for the treatment of autoinflammatory and rheumatic conditions, where overproduction of IL-1 is an important pathophysiologic process. IL-1α and IL-1β are the most studied members of the IL-1 family of cytokines and have the strongest proinflammatory effects. A naturally occurring antagonist (IL-1Ra) mitigates their proinflammatory effects. Overproduction of both IL-1α (released by inflamed/damaged pericardial cells) and IL-1β (released by inflammatory cells) is now a well-recognized therapeutic target in patients with recurrent idiopathic pericarditis. Currently, there are three available anti-IL-1 agents: anakinra (recombinant human IL-1Ra), rilonacept (a soluble decoy receptor ‘trap’, binding both IL-1α and IL-1β), and canakinumab (human monoclonal anti-IL-1β antibody). For patients with corticosteroid-dependent and colchicine-resistant recurrent pericarditis with evidence of systemic inflammation, as evidenced by elevated C-reactive protein, the efficacy and safety of anakinra (2 mg/kg/day up to 100 mg/day subcutaneously usually for at least 6 months, then tapered) and rilonacept (320 mg subcutaneously for the first day followed by 160 mg subcutaneously weekly) have been clearly demonstrated in observational studies and randomized controlled clinical trials. Severe side effects are rare and discontinuation rates are very low (<4%). The most common reported side effect is injection site reactions (>50% of patients). In this article, we describe the historical and pathophysiological background and provide a comprehensive review of these agents, which appear to be the most significant advance in medical therapy of recurrent pericarditis in the last 5 years.

Serum decoy receptor 3 (DcR3): a promising biomarker for atopic asthma in children.

Bronchial asthma is a common chronic inflammatory disease with high prevalence and morbidity, particularly in school-aged children. Decoy receptor 3 (DcR3) is a soluble decoy receptor that belongs to the tumor necrosis factor receptor superfamily and has been reported to be elevated in several allergic and inflammatory diseases. This study was designed to determine the role of DcR3 in pediatric asthma. The serum DcR3 levels were analyzed in 85 subjects (60 pediatric patients with bronchial asthma and 25 age- and sex-matched healthy control children) using the enzyme-linked immunosorbent assay technique. Patients with asthma had higher serum DcR3 levels than healthy control subjects (p = 0.007). In the atopic group of patients with asthma, the serum DcR3 levels were inversely correlated with the asthma control test score (R = - 0.392, p = 0.039). Overall, DcR3 could be a promising biomarker of atopic asthma, specifically in pediatric patients.

Role of Interleukin-1 Receptor-Like 1 (ST2) in Cerebrovascular Disease.

Following both ischemic and hemorrhagic stroke, innate immune cells initiate a proinflammatory response that further exacerbate tissue injury in the acute phase, but these cells also play an important reparative role thereafter. Numerous cytokines and signaling pathways have been implicated in driving the deleterious proinflammatory response, but less is known about the mediators that connect the initial vascular injury to the systemic immune response and the relationship between proinflammatory and reparative immune responses. The Interleukin-33 (IL-33) and serum stimulation-2 (ST2) axis is an interleukin signaling pathway that is a prime candidate to fulfill this role. In this review, we describe the biology of the IL-33/ST2 system, present evidence that its soluble decoy receptor, soluble ST2 (sST2), plays a key role in secondary neurologic injury after stroke, and discuss this in the context of the known role of IL-33/ST2 in other disease.

Salubrinal Exposes Anticancer Properties in Inflammatory Breast Cancer Cells by Manipulating the Endoplasmic Reticulum Stress Pathway.

The endoplasmic reticulum (ER) regulates protein folding, post-translational modifications, lipid synthesis, and calcium signaling to attenuate the accumulation of misfolded proteins causing ER stress and maintains cellular homeostasis. The tumor microenvironment is rich in soluble cytokines, chemokines, growth, and angiogenic factors and can drive the ER’s abnormal functioning in healthy cells. Cancer cells adapt well to the tumor microenvironment induced ER stress. We identified that the inflammatory breast cancer (IBC) cells abundantly express osteoprotegerin (OPG) and their tumor microenvironment is rich in OPG protein. OPG also called osteoclast differentiation factor/osteoclastogenesis inhibitory factor (OCIF) is a soluble decoy receptor for receptor activator of nuclear factor-kappa B ligand (RANKL). Employing mass spectrometry analysis, we identified a set of ER chaperones associated with OPG in IBC cell lysates (SUM149PT, SUM1315MO2) compared to healthy human mammary epithelial cells (HMEC). Proximity ligation assay (PLA) and immunoprecipitation assay validated the interaction between OPG and ER chaperone and master regulator of unfolded protein response (UPR) GRP78/BiP (glucose-regulated protein/Binding immunoglobulin protein). We detected remarkably high gene expression of CCAAT enhancer-binding protein homologous protein (CHOP), inositol-requiring enzyme 1 (IRE1α), protein disulfide-isomerase (PDI), PKR-like ER kinase (PERK), activating transcription factor 4 (ATF4), X-box binding protein 1 (XBP-1) and growth arrest and DNA damage-inducible protein (GADD34) in SUM149PT and SUM190PT cells when compared to HMEC. Similarly, tissue sections of human IBC expressed high levels of ER stress proteins. We evaluated cell death and apoptosis upon Salubrinal and phenylbutyrate treatment in healthy and IBC cells by caspase-3 activity and cleaved poly (ADP-ribose) polymerase (PARP) protein assay. IBC (SUM149PT and SUM190PT) cells were chemosensitive to Salubrinal treatment, possibly via inhibition in OPG secretion, upregulating ATF4, and CHOP, thus ultimately driving caspase-3 mediated IBC cell death. Salubrinal treatment upregulated PDI, which connects ER stress to oxidative stress. We observed increased ROS production and reduced cell proliferation of Salubrinal treated IBC cells. Treatment with antioxidants could rescue IBC cells from ROS and aborted cell proliferation. Our findings implicate that manipulating ER stress with Salubrinal may provide a safer and tailored strategy to target the growth of inflammatory and aggressive forms of breast cancer.

Increased Concentrations of Circulating Soluble MHC Class I-Related Chain A (sMICA) and sMICB and Modulation of Plasma Membrane MICA Expression: Potential Mechanisms and Correlation With Natural Killer Cell Activity in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a severe autoimmune disease of unknown etiology. The major histocompatibility complex (MHC) class I-related chain A (MICA) and B (MICB) are stress-inducible cell surface molecules. MICA and MICB label malfunctioning cells for their recognition by cytotoxic lymphocytes such as natural killer (NK) cells. Alterations in this recognition have been found in SLE. MICA/MICB can be shed from the cell surface, subsequently acting either as a soluble decoy receptor (sMICA/sMICB) or in CD4+ T-cell expansion. Conversely, NK cells are frequently defective in SLE and lower NK cell numbers have been reported in patients with active SLE. However, these cells are also thought to exert regulatory functions and to prevent autoimmunity. We therefore investigated whether, and how, plasma membrane and soluble MICA/B are modulated in SLE and whether they influence NK cell activity, in order to better understand how MICA/B may participate in disease development. We report significantly elevated concentrations of circulating sMICA/B in SLE patients compared with healthy individuals or a control patient group. In SLE patients, sMICA concentrations were significantly higher in patients positive for anti-SSB and anti-RNP autoantibodies. In order to study the mechanism and the potential source of sMICA, we analyzed circulating sMICA concentration in Behcet patients before and after interferon (IFN)-α therapy: no modulation was observed, suggesting that IFN-α is not intrinsically crucial for sMICA release in vivo. We also show that monocytes and neutrophils stimulated in vitro with cytokines or extracellular chromatin up-regulate plasma membrane MICA expression, without releasing sMICA. Importantly, in peripheral blood mononuclear cells from healthy individuals stimulated in vitro by cell-free chromatin, NK cells up-regulate CD69 and CD107 in a monocyte-dependent manner and at least partly via MICA-NKG2D interaction, whereas NK cells were exhausted in SLE patients. In conclusion, sMICA concentrations are elevated in SLE patients, whereas plasma membrane MICA is up-regulated in response to some lupus stimuli and triggers NK cell activation. Those results suggest the requirement for a tight control in vivo and highlight the complex role of the MICA/sMICA system in SLE.