TNF-α-Induced Apoptosis of Macrophages Following Inhibition of NF-κB: A Central Role for Disruption of Mitochondria

Inhibition of NF-κB-Mediated Proinflammatory Transcription by Ru(II) Complexes of Anti-Angiogenic Ligands in Triple-Negative Breast Cancer

Nuclear factor kappa beta (NF-κB) plays a pivotal role in breast cancer, particularly triple-negative breast cancer, by promoting inflammation, proliferation, epithelial-mesenchymal transition, metastasis, and drug resistance. Upregulation of NF-κB boosts vascular endothelial growth factor (VEGF) expression, assisting angiogenesis. The Ru(II) complexes of methyl- and dimethylpyrazolyl-benzimidazole N,N donors inhibit phosphorylation of ser536 in p65 and translocation of the NF-κB heterodimer (p50/p65) to the nucleus, disabling transcription to upregulate inflammatory signaling. The methyl- and dimethylpyrazolyl-benzimidazole inhibit VEGFR2 phosphorylation at Y1175, disrupting downstream signaling through PLC-γ and ERK1/2, ultimately suppressing Ca(II)-signaling. Partial release of the antiangiogenic ligand in a reactive oxygen species-rich environment is possible as per our observation to inhibit both NF-κB and VEGFR2 by the complexes. The complexes are nontoxic to zebrafish embryos up to 50 μM, but the ligands show strong in vivo antiangiogenic activity at 3 μM during embryonic growth in Tg(fli1:GFP) zebrafish but no visible effect on the adult phase.

A novel triptolide analog downregulates NF-κB and induces mitochondrial apoptosis pathways in human pancreatic cancer

Pancreatic cancer is the seventh leading cause of cancer-related death worldwide, and despite advancements in disease management, the 5 -year survival rate stands at only 12%. Triptolides have potent anti-tumor activity against different types of cancers, including pancreatic cancer, however poor solubility and toxicity limit their translation into clinical use. We synthesized a novel pro-drug of triptolide, (E)-19-[(1'-benzoyloxy-1'-phenyl)-methylidene]-Triptolide (CK21), which was formulated into an emulsion for in vitro and in vivo testing in rats and mice, and used human pancreatic cancer cell lines and patient-derived pancreatic tumor organoids. A time-course transcriptomic profiling of tumor organoids treated with CK21 in vitro was conducted to define its mechanism of action, as well as transcriptomic profiling at a single time point post-CK21 administration in vivo. Intravenous administration of emulsified CK21 resulted in the stable release of triptolide, and potent anti-proliferative effects on human pancreatic cancer cell lines and patient-derived pancreatic tumor organoids in vitro, and with minimal toxicity in vivo. Time course transcriptomic profiling of tumor organoids treated with CK21 in vitro revealed <10 differentially expressed genes (DEGs) at 3 hr and ~8,000 DEGs at 12 hr. Overall inhibition of general RNA transcription was observed, and Ingenuity pathway analysis together with functional cellular assays confirmed inhibition of the NF-κB pathway, increased oxidative phosphorylation and mitochondrial dysfunction, leading ultimately to increased reactive oxygen species (ROS) production, reduced B-cell-lymphoma protein 2 (BCL2) expression, and mitochondrial-mediated tumor cell apoptosis. Thus, CK21 is a novel pro-drug of triptolide that exerts potent anti-proliferative effects on human pancreatic tumors by inhibiting the NF-κB pathway, leading ultimately to mitochondrial-mediated tumor cell apoptosis.

The prognostic and therapeutic potential of HO-1 in leukemia and MDS

BACKGROUND

Heme oxygenase-1 (HO-1), a heme-degrading enzyme, is proven to have anti-apoptotic effects in several malignancies. In addition, HO-1 is reported to cause chemoresistance and increase cell survival. Growing evidence indicates that HO-1 contributes to the course of hematological malignancies as well. Here, the expression pattern, prognostic value, and the effect of HO-1 targeting in HMs are discussed.

MAIN BODY

According to the recent literature, it was discovered that HO-1 is overexpressed in myelodysplastic syndromes (MDS), chronic myeloid leukemia (CML), acute myeloblastic leukemia (AML), and acute lymphoblastic leukemia (ALL) cells and is associated with high-risk disease. Furthermore, in addition to HO-1 expression by leukemic and MDS cells, CML, AML, and ALL leukemic stem cells express this protein as well, making it a potential target for eliminating minimal residual disease (MRD). Moreover, it was concluded that HO-1 induces tumor progression and prevents apoptosis through various pathways.

CONCLUSION

HO-1 has great potential in determining the prognosis of leukemia and MDS patients. HO-1 induces resistance to several chemotherapeutic agents as well as tyrosine kinase inhibitors and following its inhibition, chemo-sensitivity increases. Moreover, the exact role of HO-1 in Chronic Lymphocytic Leukemia (CLL) is yet unknown. While findings illustrate that MDS and other leukemic patients could benefit from HO-1 targeting. Future studies can help broaden our knowledge regarding the role of HO-1 in MDS and leukemia. Video abstract.

A hierarchy of cell death pathways confers layered resistance to shigellosis in mice

Bacteria of the genus Shigella cause shigellosis, a severe gastrointestinal disease driven by bacterial colonization of colonic intestinal epithelial cells. Vertebrates have evolved programmed cell death pathways that sense invasive enteric pathogens and eliminate their intracellular niche. Previously we reported that genetic removal of one such pathway, the NAIP-NLRC4 inflammasome, is sufficient to convert mice from resistant to susceptible to oral Shigella flexneri challenge (Mitchell et al., 2020). Here, we investigate the protective role of additional cell death pathways during oral mouse Shigella infection. We find that the Caspase-11 inflammasome, which senses Shigella LPS, restricts Shigella colonization of the intestinal epithelium in the absence of NAIP-NLRC4. However, this protection is limited when Shigella expresses OspC3, an effector that antagonizes Caspase-11 activity. TNFα, a cytokine that activates Caspase-8-dependent apoptosis, also provides potent protection from Shigella colonization of the intestinal epithelium when mice lack both NAIP-NLRC4 and Caspase-11. The combined genetic removal of Caspases-1, -11, and -8 renders mice hyper-susceptible to oral Shigella infection. Our findings uncover a layered hierarchy of cell death pathways that limit the ability of an invasive gastrointestinal pathogen to cause disease.

Acinetobacter baumannii-induced infective endocarditis: new insights into pathophysiology and antibiotic resistance mechanisms

Infective endocarditis (IE), characterized by inflammation of the endocardial surface of the heart and its valves, results from infections caused by Staphylococcus, Streptococcus and Acinetobacter species and less commonly fungi. Acinetobacter-induced IE is a relatively rare condition with significant morbidity and mortality worldwide. Notably, its mortality rate is greater than that of endocarditis induced by Haemophilus species, Aggregatibacter actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens and Kingella kingae. Although it is rare, Acinetobacter-induced IE caused by A. baumannii might bring unique therapeutic challenges such as increased antibiotic resistance. Therefore, it is vital to understand perfectly the possible pathophysiologic and antibiotic resistance mechanisms adopted by A. baumannii during IE. This review discusses the probable underlying pathomechanisms involved in A. baumannii-induced IE and highlights the potential antibiotic resistance mechanisms, suggesting therapeutic targets for A. baumannii-induced IE.

Cardiac glycosides cause cytotoxicity in human macrophages and ameliorate white adipose tissue homeostasis

BACKGROUND AND PURPOSE

Cardiac glycosides inhibit Na+ /K+ -ATPase and are used to treat heart failure and arrhythmias. They can induce inflammasome activation and pyroptosis in macrophages, suggesting cytotoxicity, which remains to be elucidated in human tissues.

EXPERIMENTAL APPROACH

To determine the cell-type specificity of this cytotoxicity, we used human monocyte-derived macrophages and non-adherent peripheral blood cells from healthy donors, plus omental white adipose tissue, stromal vascular fraction-derived pre-adipocytes and adipocytes from obese patients undergoing bariatric surgery. All these cells/tissues were treated with nanomolar concentrations of ouabain (50, 100, 500 nM) to investigate the level of cytotoxicity and the mechanisms leading to cell death. In white adipose tissue, we investigated ouabain-mediated cytotoxicity by measuring insulin sensitivity, adipose tissue function and extracellular matrix deposition ex vivo.

KEY RESULTS

Ouabain induced cell death through pyroptosis and apoptosis, and was more effective in monocyte-derived macrophages compared to non-adherent peripheral blood mononuclear cell populations. This cytotoxicity is dependent on K+ flux, as ouabain causes intracellular depletion of K+ and accumulation of Na+ and Ca2+ . Consistently, the cell death caused by these ion imbalances can be rescued by addition of potassium chloride to human monocyte-derived macrophages. Remarkably, when white adipose tissue explants from obese patients are cultured with nanomolar concentrations of ouabain, this causes depletion of macrophages, down-regulation of type VI collagen levels and amelioration of insulin sensitivity ex vivo.

CONCLUSION AND IMPLICATIONS

The use of nanomolar concentration of cardiac glycosides could be an attractive therapeutic treatment for metabolic syndrome, characterized by pathogenic infiltration and activation of macrophages.

LINKED ARTICLES

This article is part of a themed issue on Inflammation, Repair and Ageing. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v179.9/issuetoc.

ADAM17, A Key Player of Cardiac Inflammation and Fibrosis in Heart Failure Development During Chronic Catecholamine Stress

Heart failure development is characterized by persistent inflammation and progressive fibrosis owing to chronic catecholamine stress. In a chronic stress state, elevated catecholamines result in the overstimulation of beta-adrenergic receptors (βARs), specifically β2-AR coupling with Gαi protein. Gαi signaling increases the activation of receptor-stimulated p38 mitogen-activated-protein-kinases (p38 MAPKs) and extracellular signal-regulated kinases (ERKs). Phosphorylation by these kinases is a common way to positively regulate the catalytic activity of A Disintegrin and Metalloprotease 17 (ADAM17), a metalloprotease that has grown much attention in recent years and has emerged as a chief regulatory hub in inflammation, fibrosis, and immunity due to its vital proteolytic activity. ADAM17 cleaves and activates proinflammatory cytokines and fibrotic factors that enhance cardiac dysfunction via inflammation and fibrosis. However, there is limited information on the cardiovascular aspect of ADAM17, especially in heart failure. Hence, this concise review provides a comprehensive insight into the structure of ADAM17, how it is activated and regulated during chronic catecholamine stress in heart failure development. This review highlights the inflammatory and fibrotic roles of ADAM17’s substrates; Tumor Necrosis Factor α (TNFα), soluble interleukin-6 receptor (sIL-6R), and amphiregulin (AREG). Finally, how ADAM17-induced chronic inflammation and progressive fibrosis aggravate cardiac dysfunction is discussed.

Reduced ELANE and SLPI expression compromises dental pulp cell activity

Background

Patients with ELANE variants and severe congenital neutropenia (SCN) commonly develop oral complications. Whether they are caused only by low neutrophil count or the combination of neutropenia and aberrant dental cells is unknown.

Methods

Genetic variant was identified with exome sequencing. Dental pulp cells isolated from the SCN patient with an ELANE mutation were investigated for gene expression, enzyme activity, proliferation, colony formation, wound healing, apoptosis, ROS, attachment, spreading and response to lipopolysaccharide.

Results

ELANE cells had diminished expression of ELANE and SLPI and reduced neutrophil elastase activity. Moreover, ELANE cells exhibited impaired proliferation, colony forming, migration, attachment and spreading; and significantly increased ROS formation and apoptosis, corresponding with increased Cyclin D1 and MMP2 levels. The intrinsic levels of TGF‐β1 and TNF‐α were significantly increased; however, IL‐6, IL‐8 and NF‐kB1 were significantly decreased in ELANE cells compared with those in controls. After exposure to lipopolysaccharide, ELANE cells grew larger, progressed to more advanced cell spreading stages and showed significantly increased SLPI, TNF‐α and NF‐kB1 and tremendously increased IL‐6 and IL‐8 expression, compared with controls.

Conclusion

This study, for the first time, suggests that in addition to neutropenia, the aberrant levels and functions of ELANE, SLPI and their downstream molecules in pulp cells play an important role in oral complications in SCN patients. In addition, pulp cells with diminished neutrophil elastase and SLPI are highly responsive to inflammation.

The Synergy of ADAM17-Induced Myocardial Inflammation and Metabolic Lipids Dysregulation During Acute Stress: New Pathophysiologic Insights Into Takotsubo Cardiomyopathy

Due to its reversible nature, Takotsubo cardiomyopathy (TTC) is considered an intriguing and fascinating cardiovascular disease characterized by a transient wall motion abnormality of the left ventricle, affecting more than one coronary artery territory, often in a circumferential apical distribution. Takotsubo cardiomyopathy was discovered by a Japanese cardiovascular expert and classified as acquired primary cardiomyopathy by the American Heart Association (AHA) in 1990 and 2006, respectively. Regardless of the extensive research efforts, its pathophysiology is still unclear; therefore, there are no well-established guidelines specifically for treating and managing TTC patients. Increasing evidence suggests that sympatho-adrenergic stimulation is strongly associated with the pathogenesis of this disease. Under acute stressful conditions, the hyperstimulation of beta-adrenergic receptors (β-ARs) resulting from excessive release of catecholamines induces intracellular kinases capable of phosphorylating and activating “A Disintegrin and Metalloprotease 17” (ADAM17), a type-I transmembrane protease that plays a central role in acute myocardial inflammation and metabolic lipids dysregulation which are the main hallmarks of TTC. However, our understanding of this is limited; hence this concise review provides a comprehensive insight into the key role of ADAM17 in acute myocardial inflammation and metabolic lipids dysregulation during acute stress. Also, how the synergy of ADAM17-induced acute inflammation and lipids dysregulation causes TTC is explained. Finally, potential therapeutic targets for TTC are also discussed.

Artemisinin protects DPSC from hypoxia and TNF-α mediated osteogenesis impairments through CA9 and Wnt signaling pathway

Dental pulp stem cells (DPSCs) possess the ability of multi-lineage differentiation, and are excellent sources of tissue engineering and regenerative medicine. Oxygen concentration and inflammation are two critical environmental factors that affect the osteogenic differentiation of DPSCs. We aimed to study the role of the antimalarial drug artemisinin on the osteogenic differentiation of human DPSCs under the hypoxia and inflammation conditions. We demonstrated that hypoxia (5% O₂) and inflammation (20 ng/mL TNF-α), alone or in combination, significantly diminished in vitro cell survival and increased apoptotic rates. Notably, hypoxia and TNF-α exerted accumulative effect in suppressing the osteogenic differentiation of DPSCs, as evidenced by reduced expression levels of osteogenesis-associated genes including ALP, RUNX2 and OCN in osteogenic condition, as well as reduced mineral nodules formation as indicated by alizarin red staining. Artemisinin at the dose of 40 μM markedly reversed the suppression in cell survival caused by hypoxia or inflammation, and reduced apoptotic rates and the expressions of pro-apoptotic proteins. Additionally, artemisinin restored osteogenic differentiation of DPSCs under the hypoxia or/and inflammation conditions. Moreover, the beneficial effect of artemisinin was dependent on upregulated expression of CA9 and CA9-mediated antioxidant responses, as CA9 knockdown abolished the protective role of artemisinin on DPSC osteogenesis. Furthermore, while hypoxia or/and inflammation significantly inactivated the Wnt/β-catenin signaling in DPSCs, additional exposure to artemisinin re-activated this pathway to promote osteogenic differentiation of DPSCs. Our results provide novel insight on the link between artemisinin and DPSC osteogenesis, and suggest promising artemisinin-based strategies for better dentin/pulp tissue engineering.

ROS-Mediated Necrosis by Glycolipid Biosurfactants on Lung, Breast, and Skin Melanoma Cells

Cancer is one of the major leading causes of death worldwide. Designing the new anticancer drugs is remained a challenging task due to ensure complexicity of cancer etiology and continuosly emerging drug resistance. Glycolipid biosurfactants are known to possess various biological activities including antimicrobial, anticancer and antiviral properties. In the present study, we sought to decipher the mechanism of action of the glycolipids (lactonic-sophorolipd, acidic-sophorolipid, glucolipid, and bolalipid) against cancer cells using lung cancer cell line (A549), breast cancer cell line (MDA-MB 231), and mouse skin melanoma cell line (B16F10). Scratch assay and fluorescence microscopy revealed that glycolipids inhibit tumorous cell migration possibly by inhibiting actin filaments. Fluorescence activated cell sorter (FACS) analysis exhibited that lactonic sophorolipid and glucolipid both induced the reactive oxygen species, altered the mitochondrial membrane potential (ΔΨ) and finally led to the cell death by necrosis. Furthermore, combinatorial effect of lactonic-sophorolipd and glucolipid demonstrated synergistic interaction on A549 cell line whereas additive effect on MDA-MB 231 and B16F10 cell lines. Our study has highlighted that lactonic-sophorolipd and glucolipid could be useful for developing new anticancer drugs either alone or in combination.

Testosterone attenuates pulmonary epithelial inflammation in male rats of COPD model through preventing NRF1-derived NF-κB signaling

Testosterone deficiency is common in male patients with chronic obstructive pulmonary disease (COPD) and may correlate with the deterioration of COPD. Clinical research suggests that testosterone replacement therapy may slow the COPD progression, but the specific biological pathway remains unclear. In this study, we explored the effect of testosterone on pulmonary inflammation in male COPD rats. The animals were co-treated with lipopolysaccharide (LPS) and cigarette to induce COPD. In COPD rats, nuclear respiratory factor 1 (NRF1) and NF-κB p65 were upregulated. In cigarette smoke extract (CSE)-, LPS-, or the combination of CSE and LPS-treated L132 cells, NRF1 and p65 were also upregulated. Silencing NRF1 resulted in the downregulation of p65. ChIP‒seq, ChIP‒qPCR, and luciferase results showed that NRF1 transcriptionally regulated p65. Both male and female COPD rats showed an upregulated NRF1 level and similar pulmonary morphology. But NRF1 was further upregulated in male castrated rats. Further supplementing testosterone in castrated male rats significantly reduced NRF1, pulmonary lesions, and inflammation. Supplementation of testosterone also reduced the phosphorylation of p65 and IKKβ induced by LPS or CSE in L132 cells. Our results suggest that testosterone plays a protective role in pulmonary epithelial inflammation of COPD through inhibition of NRF1-derived NF-κB signaling and the phosphorylation of p65.

The Effect of Deflazacort Treatment on the Functioning of Skeletal Muscle Mitochondria in Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a severe hereditary disease caused by a lack of dystrophin, a protein essential for myocyte integrity. Mitochondrial dysfunction is reportedly responsible for DMD. This study examines the effect of glucocorticoid deflazacort on the functioning of the skeletal-muscle mitochondria of dystrophin-deficient mdx mice and WT animals. Deflazacort administration was found to improve mitochondrial respiration of mdx mice due to an increase in the level of ETC complexes (complexes III and IV and ATP synthase), which may contribute to the normalization of ATP levels in the skeletal muscle of mdx animals. Deflazacort treatment improved the rate of Ca2+ uniport in the skeletal muscle mitochondria of mdx mice, presumably by affecting the subunit composition of the calcium uniporter of organelles. At the same time, deflazacort was found to reduce the resistance of skeletal mitochondria to MPT pore opening, which may be associated with a change in the level of ANT2 and CypD. In this case, deflazacort also affected the mitochondria of WT mice. The paper discusses the mechanisms underlying the effect of deflazacort on the functioning of mitochondria and contributing to the improvement of the muscular function of mdx mice.

Serum deprivation initiates adaptation and survival to oxidative stress in prostate cancer cells

Inadequate nutrient intake leads to oxidative stress disrupting homeostasis, activating signaling, and altering metabolism. Oxidative stress serves as a hallmark in developing prostate lesions, and an aggressive cancer phenotype activating mechanisms allowing cancer cells to adapt and survive. It is unclear how adaptation and survival are facilitated; however, literature across several organisms demonstrates that a reversible cellular growth arrest and the transcription factor, nuclear factor-kappaB (NF-κB), contribute to cancer cell survival and therapeutic resistance under oxidative stress. We examined adaptability and survival to oxidative stress following nutrient deprivation in three prostate cancer models displaying varying degrees of tumorigenicity. We observed that reducing serum (starved) induced reactive oxygen species which provided an early oxidative stress environment and allowed cells to confer adaptability to increased oxidative stress (H₂O₂). Measurement of cell viability demonstrated a low death profile in stressed cells (starved + H₂O₂), while cell proliferation was stagnant. Quantitative measurement of apoptosis showed no significant cell death in stressed cells suggesting an adaptive mechanism to tolerate oxidative stress. Stressed cells also presented a quiescent phenotype, correlating with NF-κB nuclear translocation, suggesting a mechanism of tolerance. Our data suggests that nutrient deprivation primes prostate cancer cells for adaptability to oxidative stress and/or a general survival mechanism to anti-tumorigenic agents.

Integrated Microfluidic Device for Functional Secretory Immunophenotyping of Immune Cells

Integrated platforms for automatic assessment of cellular functional secretory immunophenotyping could have a widespread use in the diagnosis, real-time monitoring, and therapy evaluation of several pathologies. We present a microfluidic platform with integrated biosensors and culture chambers to measure cytokine secretion from a consistent and uniform number of immune cells. The biosensor relies on a fluorescence sandwich immunoassay enabled by the mechanically induced trapping of molecular interactions method. The platform contains 32 cell culture chambers, each patterned with an array of 492 microwells, to capture and analyze both adherent and nonadherent immune cells. Multiple stimuli can be delivered to a set of culture chambers. Per chamber, we were able to capture consistently 1113 ± 191 of blood-derived monocytes and neutrophils and 348 ± 37 THP-1 monocytes. Good occupancy efficiencies of ∼70% with a uniformity of ∼90% across all of the culture chambers of the device were achieved. Furthermore, we demonstrate that up to 96% of cells remain viable for the first 48 h. The employment of epoxy-modified glass substrates and active mixing enhanced the biosensing performance compared to the use of bare glass and simple diffusion. Finally, we performed functional secretory analysis of interleukin-8 and tumor necrosis factor alpha from human neutrophils and monocytes, stimulated with various doses of lipopolysaccharide and phorbol 12-myristate 13-acetate-ionomycin, respectively. We foresee the employment of our microfluidic platform in the diagnosis of different pathologies where alterations in cytokine secretion patterns can be used as biomarkers.

JNK Signaling as a Key Modulator of Soft Connective Tissue Physiology, Pathology, and Healing

In healthy individuals, the healing of soft tissues such as skin after pathological insult or post injury follows a relatively predictable and defined series of cell and molecular processes to restore tissue architecture and function(s). Healing progresses through the phases of hemostasis, inflammation, proliferation, remodeling, and concomitant with re-epithelialization restores barrier function. Soft tissue healing is achieved through the spatiotemporal interplay of multiple different cell types including neutrophils, monocytes/macrophages, fibroblasts, endothelial cells/pericytes, and keratinocytes. Expressed in most cell types, c-Jun N-terminal kinases (JNK) are signaling molecules associated with the regulation of several cellular processes involved in soft tissue wound healing and in response to cellular stress. A member of the mitogen-activated protein kinase family (MAPK), JNKs have been implicated in the regulation of inflammatory cell phenotype, as well as fibroblast, stem/progenitor cell, and epithelial cell biology. In this review, we discuss our understanding of JNKs in the regulation of cell behaviors related to tissue injury, pathology, and wound healing of soft tissues. Using models as diverse as Drosophila, mice, rats, as well as human tissues, research is now defining important, but sometimes conflicting roles for JNKs in the regulation of multiple molecular processes in multiple different cell types central to wound healing processes. In this review, we focus specifically on the role of JNKs in the regulation of cell behavior in the healing of skin, cornea, tendon, gingiva, and dental pulp tissues. We conclude that while parallels can be drawn between some JNK activities and the control of cell behavior in healing, the roles of JNK can also be very specific modes of action depending on the tissue and the phase of healing.

TNF-α promoter polymorphisms (G-238A and G-308A) are associated with susceptibility to Systemic Lupus Erythematosus (SLE) and P. falciparum malaria: a study in malaria endemic area

Tumor necrosis factor-α (TNF-α) is a proinflammatory cytokine associated with autoimmune and infectious diseases. Importance of TNF-α in P. falciparum malaria and systemic lupus erythematosus (SLE) have been demonstrated. However, association of functional promoter variants with SLE and malaria is lacking in malaria endemic population. A total of 204 female SLE patients and 224 age and sex matched healthy controls were enrolled in the study. Three hundred fourteen P. falciparum infected patients with different clinical phenotypes were included. TNF-α polymorphisms (G-238A & G-308A) were genotyped by PCR-RFLP. Plasma levels of TNF-α was quantified by ELISA. Heterozygous mutants and minor alleles of TNF-α (G-238A and G-308A) polymorphisms were significantly higher in SLE patients compared to healthy controls and associated with development of lupus nephritis. In addition, both promoter variants were associated with severe P. falciparum malaria. SLE patients demonstrated higher levels of plasma TNF-α compared to healthy controls. TNF-α (G-238A and G-308A) variants were associated with higher plasma TNF-α. In conclusion, TNF-α (G-238A & G-308A) variants are associated with higher plasma TNF-α levels in SLE patients residing in malaria endemic areas and could be a contributing factor in the development of SLE and susceptibility to severe P. falciparum malaria.

What Is Nuclear Factor Kappa B (NF-κB) Doing in and to the Mitochondrion?

A large body of literature supports the idea that nuclear factor kappa B (NF-κB) signaling contributes to not only immunity, but also inflammation, cancer, and nervous system function. However, studies on NF-κB activity in mitochondrial function are much more limited and scattered throughout the literature. For example, in 2001 it was first published that NF-κB subunits were found in the mitochondria, including not only IkBα and NF-κB p65 subunits, but also NF-κB pathway proteins such as IKKα, IKKβ, and IKKγ, but not much follow-up work has been done to date. Upon further thought the lack of studies on NF-κB activity in mitochondrial function is surprising given the importance and the evolutionary history of both NF-κB and the mitochondrion. Both are ancient in their appearance in our biological record where both contribute substantially to cell survival, cell death, and the regulation of function and/or disease. Studies also show NF-κB can influence mitochondrial function from outside the mitochondria. Therefore, it is essential to understand the complexity of these roles both inside and out of this organelle. In this review, an attempt is made to understand how NF-κB activity contributes to overall mitochondrial function – both inside and out. The discussion at times is speculative and perhaps even provocative to some, since NF-κB does not yet have defined mitochondrial targeting sequences for some nuclear-encoded mitochondrial genes and mechanisms of mitochondrial import for NF-κB are not yet entirely understood. Also, the data associated with the mitochondrial localization of proteins must be yet further proved with additional experiments.

Novel steroidal 1,3,4-thiadiazines: Synthesis and biological evaluation in androgen receptor-positive prostate cancer 22Rv1 cells

A flexible approach to previously unknown spirofused and linked 1,3,4-thiadiazine derivatives of steroids with selective control of heterocyclization patterns is disclosed. (N-Arylcarbamoyl)spiroandrostene-17,6' [1,3,4]thiadiazines and (N-arylcarbamoyl)17-[1',3',4']thiadiazine-substituted androstenes, novel types of heterosteroids, were prepared from 16β,17β-epoxypregnenolone and 21-bromopregna-5,16-dien-20-one in good to high yields by the treatment with oxamic acid thiohydrazides. The synthesized compounds were screened for antiproliferative activity against the human androgen receptor-positive prostate cancer cell line 22Rv1. Most of (N-arylcarbamoyl)17-[1',3',4']thiadiazine-substituted androstenes exhibit better antiproliferative potency (IC₅₀ = 2.1-6.6 µM) than the antiandrogen bicalutamide. Compounds 7d with IC₅₀ = 3.0 μM and 7j with IC₅₀ = 2.1 μM proved to be the most active in the series under study. Lead synthesized compound 7j downregulates AR expression and activity in 22Rv1 cells. NF-κB activity is also blocked in 7j-treated 22Rv1 cells. Apoptosis is considered as a possible mechanism of 7j-induced cell death.

Intracellular Transport and Cytotoxicity of the Protein Toxin Ricin

Ricin can be isolated from the seeds of the castor bean plant (Ricinus communis). It belongs to the ribosome-inactivating protein (RIP) family of toxins classified as a bio-threat agent due to its high toxicity, stability and availability. Ricin is a typical A-B toxin consisting of a single enzymatic A subunit (RTA) and a binding B subunit (RTB) joined by a single disulfide bond. RTA possesses an RNA N-glycosidase activity; it cleaves ribosomal RNA leading to the inhibition of protein synthesis. However, the mechanism of ricin-mediated cell death is quite complex, as a growing number of studies demonstrate that the inhibition of protein synthesis is not always correlated with long term ricin toxicity. To exert its cytotoxic effect, ricin A-chain has to be transported to the cytosol of the host cell. This translocation is preceded by endocytic uptake of the toxin and retrograde traffic through the trans-Golgi network (TGN) and the endoplasmic reticulum (ER). In this article, we describe intracellular trafficking of ricin with particular emphasis on host cell factors that facilitate this transport and contribute to ricin cytotoxicity in mammalian and yeast cells. The current understanding of the mechanisms of ricin-mediated cell death is discussed as well. We also comment on recent reports presenting medical applications for ricin and progress associated with the development of vaccines against this toxin.

Bioactive Compounds, Antioxidant Activity, and Biological Effects of European Cranberry (Vaccinium oxycoccos)

Lesser known fruits or underutilized fruit species are recently of great research interest due to the presence of phytochemicals that manifest many biological effects. European cranberry, Vaccinium oxycoccos fruit, as an important representative of this group, is a valuable source of antioxidants and other biologically active substances, similar to American cranberry (V. macrocarpon) which is well known and studied. European cranberry fruit is rich especially in polyphenolic compounds anthocyanins (12.4⁻207.3 mg/100 g fw), proanthocyanins (1.5⁻5.3 mg/100 g fw), and flavonols, especially quercetin (0.52⁻15.4 mg/100 g fw), which mostly contribute to the antioxidant activity of the fruit. Small cranberry is also important due to its various biological effects such as urinary tract protection (proanthocyanidins), antibacterial and antifungal properties (quercetin, proanthocyanidins, anthocyanins), cardioprotective (proanthocyanidins) and anticancer activities (proanthocyanidins), and utilization in food (juice drinks, jams, jellies, sauces, additive to meat products) and pharmacological industries, and in folk medicine.

TNFR2 unlocks a RIPK1 kinase activity-dependent mode of proinflammatory TNFR1 signaling

TNF is not only a major effector molecule of PAMP/DAMP-activated macrophages, but also regulates macrophage function and viability. We recently demonstrated that TNFR2 triggers necroptosis in macrophages with compromised caspase activity by two cooperating mechanisms: induction of endogenous TNF with subsequent stimulation of TNFR1 and depletion of cytosolic TRAF2-cIAP complexes. Here we show that TNFR2 activation in caspase-inhibited macrophages results in the production of endogenous TNF and TNFR1 stimulation followed by upregulation of A20, TRAF1, IL-6, and IL-1β. Surprisingly, TNFR1-mediated induction of IL-6 and IL-1β was clearly evident in response to TNFR2 stimulation but occurred not or only weakly in macrophages selectively and directly stimulated via TNFR1. Moreover, TNFR2-induced TNFR1-mediated gene induction was largely inhibited by necrostatin-1, whereas upregulation of A20 and TRAF1 by direct and exclusive stimulation of TNFR1 remained unaffected by this compound. Thus, treatment with TNFR2/ZVAD enables TNFR1 in macrophages to stimulate gene induction via a pathway requiring RIPK1 kinase activity. TNFR2/ZVAD-induced production of IL-6 and IL-1β was largely blocked in necroptosis-resistant MLKL- and RIPK3-deficient macrophages, whereas induction of A20 and TRAF1 remained unaffected. In sum, our results show that in caspase-inhibited macrophages TNFR2 not only triggers TNF/TNFR1-mediated necroptosis but also TNF/TNFR1-mediated RIPK3/MLKL-dependent and -independent gene induction.

Sympathetic innervation regulates macrophage activity in rats with polycystic ovary

Polycystic ovarian syndrome (PCOS) is a low-grade inflammatory disease characterized by hyperandrogenism and ovarian hyperinnervation. The aim of this work is to investigate whether in vivo bilateral superior ovarian nerve (SON) section in adult rats with estradiol valerate-induced PCOS (PCO rats) affects macrophage spleen cells (MФ) and modifies the steroidogenic ability of their secretions. Culture media of MФ from PCO rats and PCO rats with SON section (PCO-SON rats) were used to stimulate in vitro intact ovaries. Compared with macrophages PCO, macrophages from PCO-SON rats released less tumor necrosis factor-α and nitric oxide, expressed lower Bax and Nfkb mRNA and showed reduced TUNEL staining. Also, in PCO rats, the SON section decreased kisspeptin and nerve growth factor mRNA expressions, without changes in Trka receptor mRNA levels. Macrophage secretions from PCO-SON rats decreased androstenedione and stimulated progesterone release in PCO ovaries, compared to macrophage secretions from PCO rats. No changes were observed in ovarian estradiol response. These findings emphasize the importance of the SON in spleen MΦ, since its manipulation leads to secondary modifications of immunological and neural mediators, which might influence ovarian steroidogenesis. In PCO ovaries, the reduction of androstenedione and the improvement of progesterone release induced by PCO-SON MΦ secretion, might be beneficial considering the hormonal anomalies characteristic of PCOS. We present functional evidence that modulation of the immune-endocrine function by peripheral sympathetic nervous system might have implications for understanding the pathophysiology of PCOS.

Antitumor Macrophage Response to Bacillus pumilus Ribonuclease (Binase)

Extracellular bacterial ribonucleases such as binase from Bacillus pumilus possess cytotoxic activity against tumor cells with a potential for clinical application. Moreover, they may induce activation of tumor-derived macrophages either into the M1-phenotype with well-documented functions in the regulation of the antitumor immune response or into M2-macrophages that may stimulate tumor growth, metastasis, and angiogenesis. In this study, binase or endogenous RNase1 (but not RNA or short oligonucleotides) stimulated the expression of activated NF-κB p65 subunit in macrophages. Since no changes in MyD88 and TRIF adaptor protein expression were observed, toll-like receptors may not be involved in RNase-related NF-κB pathway activation. In addition, short exposure (0.5 hr) to binase induced the release of cytokines such as IL-6, МСР-1, or TNF-α (but not IL-4 and IL-10), indicative for the polarization into antitumor M1-macrophages. Thus, we revealed increased expression of activated NF-κB p65 subunit in macrophages upon stimulation by binase and RNase1, but not RNA or short oligonucleotides.

SNAPIN is critical for lysosomal acidification and autophagosome maturation in macrophages

We previously observed that SNAPIN, which is an adaptor protein in the SNARE core complex, was highly expressed in rheumatoid arthritis synovial tissue macrophages, but its role in macrophages and autoimmunity is unknown. To identify SNAPIN's role in these cells, we employed siRNA to silence the expression of SNAPIN in primary human macrophages. Silencing SNAPIN resulted in swollen lysosomes with impaired CTSD (cathepsin D) activation, although total CTSD was not reduced. Neither endosome cargo delivery nor lysosomal fusion with endosomes or autophagosomes was inhibited following the forced silencing of SNAPIN. The acidification of lysosomes and accumulation of autolysosomes in SNAPIN-silenced cells was inhibited, resulting in incomplete lysosomal hydrolysis and impaired macroautophagy/autophagy flux. Mechanistic studies employing ratiometric color fluorescence on living cells demonstrated that the reduction of SNAPIN resulted in a modest reduction of H⁺ pump activity; however, the more critical mechanism was a lysosomal proton leak. Overall, our results demonstrate that SNAPIN is critical in the maintenance of healthy lysosomes and autophagy through its role in lysosome acidification and autophagosome maturation in macrophages largely through preventing proton leak. These observations suggest an important role for SNAPIN and autophagy in the homeostasis of macrophages, particularly long-lived tissue resident macrophages.

Anti-CD24 neutralizing antibody exacerbates Concanavalin A-induced acute liver injury in mice via liver M1 macrophages

Liver largely relies on its innate immunity to initiate quick and effective defense against potentially toxic agents, and innate immune cells are major players in this process. However, excessive inflammation due to out-of-control immune response may eventually cause liver injury. Thus, it is important to fully understand the regulatory mechanisms associated with liver inflammation. Here we showed that anti-CD24 neutralizing antibody exacerbated hepatic inflammation in a Con A-induced acute liver injury murine model. Our results supported that hepatic macrophages were required for anti-CD24 neutralizing antibody-aggravated liver inflammation, as depletion of macrophages significantly alleviated Con A-induced inflammation. M1 macrophages, but not M2 macrophages, were specifically induced by Con A, and more greatly by Con A in combination with anti-CD24 neutralizing antibody. The combined treatment further promoted M1 hepatic macrophages to express TNF-α, which increased hepatocytes apoptosis. Taken together, these data suggest that anti-CD24 neutralizing antibody plays an important role in aggravating inflammation in the process of Con A-induced acute liver injury in mice. The possible mechanism might involve the enhanced secretion of TNF-α by hepatic M1 macrophages. This study also implicates a role for CD24 in negative regulation of Con A-induced liver inflammation.

Activation of TNFR2 sensitizes macrophages for TNFR1-mediated necroptosis

Macrophages express TNFR1 as well as TNFR2 and are also major producers of tumor necrosis factor (TNF), especially upon contact with pathogen-associated molecular patterns. Consequently, TNF not only acts as a macrophage-derived effector molecule but also regulates the activity and viability of macrophages. Here, we investigated the individual contribution of TNFR1 and TNFR2 to TNF-induced cell death in macrophages. Exclusive stimulation of TNFR1 showed no cytotoxic effect whereas selective stimulation of TNFR2 displayed mild cytotoxicity. Intriguingly, the latter was strongly enhanced by the caspase inhibitor zVAD-fmk. The strong cytotoxic activity of TNFR2 in the presence of zVAD-fmk was reversed by necrostatin-1, indicating necroptotic cell death. TNFR1- and TNF-deficient macrophages turned out to be resistant against TNFR2-induced cell death. In addition, the cIAP-depleting SMAC mimetic BV6 also enforced TNF/TNFR1-mediated necroptotic cell death in the presence of zVAD-fmk. In sum, our data suggest a model in which TNFR2 sensitizes macrophages for endogenous TNF-induced TNFR1-mediated necroptosis by the known ability of TNFR2 to interfere with the survival activity of TRAF2-cIAP1/2 complexes.

Effect of Hypoxia-regulated Polo-like Kinase 3 (Plk3) on Human Limbal Stem Cell Differentiation

Hypoxic conditions in the cornea affect epithelial function by activating Polo-like kinase 3 (Plk3) signaling and the c-Jun·AP-1 transcription complex, resulting in apoptosis of corneal epithelial cells. Hypoxic stress in the culture conditions also regulates limbal stem cell growth and fate. In this study, we demonstrate that there is a differential response of Plk3 in hypoxic stress-induced primary human limbal stem (HLS) and corneal epithelial (HCE) cells, resulting in different pathways of cell fate. We found that hypoxic stress induced HLS cell differentiation by down-regulating Plk3 activity at the transcription level, which was opposite to the effect of hypoxic stress on Plk3 activation to elicit HCE cell apoptosis, detected by DNA fragmentation and TUNEL assays. Hypoxic stress-induced increases in c-Jun phosphorylation/activation were not observed in HLS cells because Plk3 expression and activity were suppressed in hypoxia-induced HLS cells. Instead, hypoxic stress-induced HLS cell differentiation was monitored by cell cycle analysis and measured by the decrease and increase in p63 and keratin 12 expression, respectively. Hypoxic stress-induced Plk3 signaling to regulate c-Jun activity, resulting in limbal stem cell differentiation and center epithelial apoptosis, was also found in the corneas of wild-type and Plk3(-/-)-deficient mice. Our results, for the first time, reveal the differential effects of hypoxic stress on Plk3 activity in HLS and HCE cells. Instead of apoptosis, hypoxic stress suppresses Plk3 activity to protect limbal stem cells from death and to allow the process of HLS cell differentiation.

Biaryl amide compounds reduce the inflammatory response in macrophages by regulating Dectin-1

Macrophages are archetypal innate immune cells that play crucial roles in the recognition and phagocytosis of invading pathogens, which they identify using pattern recognition receptors (PRRs). Dectin-1 is essential for antifungal immune responses, recognizing the fungal cellular component β-glucan, and its role as a PRR has been of increasing interest. Previously, we discovered and characterized a novel biaryl amide compound, MPS 03, capable of inhibiting macrophage phagocytosis of zymosan. Therefore, in this study we aimed to identify other biaryl amide compounds with greater effectiveness than MPS 03, and elucidate their cellular mechanisms. Several MPS 03 derivatives were screened, four of which reduced zymosan phagocytosis in a similar manner to MPS 03. To establish whether such phagocytosis inhibition influenced the production of inflammatory mediators, pro-inflammatory cytokine and nitric oxide (NO) levels were measured. The production of TNF-α, IL-6, IL-12, and NO was significantly reduced in a dose-dependent manner. Moreover, the inflammation-associated MAPK signaling pathway was also affected by biaryl amide compounds. To investigate the underlying cellular mechanism, PRR expression was measured. MPS 03 and its derivatives were found to inhibit zymosan phagocytosis by decreasing Dectin-1 expression. Furthermore, when macrophages were stimulated by zymosan after pretreatment with biaryl amide compounds, downstream transcription factors such as NFAT, AP-1, and NF-κB were downregulated. In conclusion, biaryl amide compounds reduce zymosan-induced inflammatory responses by downregulating Dectin-1 expression. Therefore, such compounds could be used to inhibit Dectin-1 in immunological experiments and possibly regulate excessive inflammatory responses.

ATM kinase promotes both caspase-8 and caspase-9 activation during TNF-α-induced apoptosis of HeLa cells

In this study, we show that atraxia telangiectasia mutated kinase (ATM) activity is generally upregulated by different apoptotic stimuli, i.e. TNF-α, TRAIL, paclitaxel, or UV. Apoptotic progression is markedly attenuated by siATM-RNA through down regulation of caspase-8 and caspase-9 in parallel with decreases in FLIP-S (short form of cellular FLICE inhibitory protein) protein levels and Bid cleavage. In addition, ATM activity is upregulated through t-Cdc6 while caspase-8 and caspase-9 activities increase. Taken together, we suggest that ATM regulates caspase-8 activation by influencing levels of FLIP-S, ATM kinase activity is upregulated by t-Cdc6, and increased ATM activity plays an essential role in the amplification of apoptosis in TNF-α-stimulated HeLa cells.

Differential induction of macrophage cell death by antigens of a clustered and a non-clustered multidrug-resistant Mycobacterium tuberculosis strain from Haarlem family

Some multidrug-resistant (MDR) Mycobacterium tuberculosis (Mtb) genotypes are the cause of large outbreaks, including strain M identified in Argentina. In contrast, its kin strain 410 has only caused a single case to date. Cell wall antigens from Mtb were associated with the modulation of macrophage (MΦ) cell death, and the ability to inhibit of MΦ apoptosis is considered a virulence mechanism. In this study, the ability these two clinical isolates with divergent epidemiology to induce MΦ cell death was evaluated using whole inactivated bacteria. We showed that gamma-irradiated (I-) strains induced MΦ necrosis, the strongest inducer being I-410. Cell death biased towards apoptosis with the heat-killed (hk) strains, both hk-MDR strains being poorer inducers of MΦ apoptosis than was H37Rv. These effects were partly due to their ability to induce anti-apoptotic mechanisms which were not related to the lack of tumor necrosis factor alpha induction or a compensatory effect of interleukin-10. The most noticeable difference between strain M and strain 410 was the ability shown by hk-M to interfere with apoptosis induced by hk-H37Rv. Thus, heat-stable and heat-labile antigens from these epidemiologically divergent Mtb strains differ in their ability to manipulate MΦ death.

A requirement for the p85 PI3K adapter protein BCAP in the protection of macrophages from apoptosis induced by endoplasmic reticulum stress

Macrophages are innate immune cells that play key roles in regulation of the immune response and in tissue injury and repair. In response to specific innate immune stimuli, macrophages may exhibit signs of endoplasmic reticulum (ER) stress and progress to apoptosis. Factors that regulate macrophage survival under these conditions are poorly understood. In this study, we identified B cell adapter protein (BCAP), a p85 PI3K-binding adapter protein, in promoting survival in response to the combined challenge of LPS and ER stress. BCAP was unique among nine PI3K adapter proteins in being induced >10-fold in response to LPS. LPS-stimulated macrophages incubated with thapsigargin, a sarcoplasmic/endoplasmic reticulum calcium ATPase inhibitor that induces ER stress, underwent caspase-3 activation and apoptosis. Macrophages from BCAP(-/-) mice exhibited increased apoptosis in response to these stimuli. BCAP-deficient macrophages demonstrated decreased activation of Akt, but not ERK, and, unlike BCAP-deficient B cells, expressed normal amounts of the NF-κB subunits, c-Rel and RelA. Retroviral transduction of BCAP-deficient macrophages with wild-type BCAP, but not a Y4F BCAP mutant defective in binding the SH2 domain of p85 PI3K, reversed the proapoptotic phenotype observed in BCAP-deficient macrophages. We conclude that BCAP is a nonredundant PI3K adapter protein in macrophages that is required for maximal cell survival in response to ER stress. We suggest that as macrophages engage their pathogenic targets, innate immune receptors trigger increased expression of BCAP, which endows them with the capacity to withstand further challenges from ongoing cellular insults, such as ER stress.

Harnessing programmed cell death as a therapeutic strategy in rheumatic diseases

Programmed cell death (PCD) is a key process in the regulation of immune cell development and peripheral immune homeostasis. Caspase-dependent apoptosis, as well as a number of alternative cell death mechanisms, account for immune cell PCD induced by cell-intrinsic and extrinsic pathways. In animal models, compelling evidence has emerged that genetic defects in PCD can result in autoimmune disease. Autoimmune disease can arise from single-gene mutations that affect PCD, and defective PCD has been observed in some tissues and cells from patients with rheumatic disease. Selectively inducing PCD in autoreactive B and T cells is very attractive as a therapeutic strategy because it offers the possibility of permanent elimination of these pathogenic cell subsets. In addition, the anti-inflammatory effects of apoptotic cells may add to the therapeutic benefit of induced PCD. Immune cell subsets vary widely in their sensitivity to specific inducers of cell death, and understanding these differences is key to predicting the outcome of inducing apoptosis for therapeutic means. Here, we review approaches that have been used to induce PCD in the treatment of autoimmune disease, and describe the prospects of bringing these experimental strategies into clinical practice.

The induction of apoptosis by Shiga toxins and ricin

Shiga toxins and ricin are ribosome-inactivating proteins which share the property of inhibiting protein synthesis by catalytic inactivation of eukaryotic ribosomes. There is now abundant evidence that Shiga toxins and ricin induce apoptosis in epithelial, endothelial, lymphoid and myeloid cells in vitro, and in multiple organs in animals when administered these toxins. Many studies suggest that protein synthesis inhibition and apoptosis induction mediated by Shiga toxins and ricin may be dissociated. In some cells, non-enzymatic toxin components (Shiga toxin B-subunits, ricin B-chain) appear capable of inducing apoptosis. The toxins appear capable of activating components of both the extrinsic or death receptor-mediated and intrinsic or mitochondrial-mediated pathways of apoptosis induction. Although the toxins have been shown to be capable of activating several cell stress response pathways, the precise signaling mechanisms by which Shiga toxins and ricin induce apoptosis remain to be fully characterized. This chapter provides an overview of studies describing Shiga toxin- and ricin-induced apoptosis and reviews evidence that signaling through the ribotoxic stress response and the unfolded protein response may be involved in apoptosis induction in some cell types.

Cell-death-mode switch from necrosis to apoptosis in hydrogen peroxide treated macrophages

Cell death is typically defined either as apoptosis or necrosis. Because the consequences of apoptosis and necrosis are quite different for an entire organism, the investigation of the cell-death-mode switch has considerable clinical significance. The existence of a necrosis-to-apoptosis switch induced by hydrogen peroxide in macrophage cell line RAW 264.7 cells was confirmed by using flow cytometry and fluorescence microscopy. With the help of computational simulations, this study predicted that negative feedbacks between NF-κB and MAPKs are implicated in converting necrosis into apoptosis in macrophages exposed to hydrogen peroxide, which has significant implications.

TNF-alpha-induced mitochondrial alterations in human T cells requires FADD and caspase-8 activation but not RIP and caspase-3 activation

Although much is known about how TNF-alpha induces apoptosis in the presence of inhibitors of protein synthesis, little is known about how it induces apoptosis without these inhibitors. In this report we investigated temporal sequence of events induced by TNF-alpha in the absence of protein synthesis. Regardless of whether we measured the effects by plasma membrane phosphotidylserine accumulation, by DNA strand breaks, or activation of caspases, significant changes were observed only between 12-24 h of TNF-alpha treatment. One of the earliest changes observed after TNF-alpha treatment was mitochondrial swelling at 10 min; followed by cytochrome c and Smac release at 10-30 min, and then heterochromatin clumping occurred at 60 min. While genetic deletion of receptor-interaction protein (RIP) had no effect on TNF-alpha-induced mitochondrial damage, deletion of Fas-associated death domain (FADD) abolished the TNF-induced mitochondrial swelling. Since pan-caspase inhibitor z-VAD-fmk abolished the TNF-alpha-induced mitochondrial changes, z-DEVD-fmk, an inhibitor of caspase-3 had no effect, suggesting that TNF-alpha-induced mitochondrial changes or cytochrome c and Smac release requires caspase-8 but not caspase-3 activation. Overall, our results indicated that mitochondrial changes are early events in TNF-alpha-induced apoptosis and that these mitochondrial changes require recruitment of FADD and caspase-8 activation, but not caspase-3 activation or RIP recruitment.

T cell and APC dynamics in situ control the outcome of vaccination

The factors controlling the progression of an immune response to generation of protective memory are poorly understood. We compared the in situ and ex vivo characteristics of CD8 T cells responding to different forms of the same immunogen. Immunization with live Listeria monocytogenes, irradiated L. monocytogenes (IRL), or heat-killed L. monocytogenes (HKL) induced rapid activation of CD8 T cells. However, only IRL and live L. monocytogenes inoculation induced sustained proliferation and supported memory development. Gene and protein expression analysis revealed that the three forms of immunization led to three distinct transcriptional and translational programs. Prior to cell division, CD8 T cell-dendritic cell clusters formed in the spleen after live L. monocytogenes and IRL but not after HKL immunization. Furthermore, HKL immunization induced rapid remodeling of splenic architecture, including loss of marginal zone macrophages, which resulted in impaired bacterial clearance. These results identify initial characteristics of a protective T cell response that have implications for the development of more effective vaccination strategies.

Effect of hypoxic stress-activated Polo-like kinase 3 on corneal epithelial wound healing

PURPOSE

Hypoxia/reoxygenation conditions can generate oxidative stresses resulting in the suppression of cell proliferation and the delay of corneal epithelial wound healing. The purpose of this study was to investigate the cellular mechanism involving the role of the stress-responsive Polo-like kinase 3 (Plk3) in hypoxic stress-induced delay of corneal epithelial wound healing.

METHODS

Plk3 activities were determined by immunochemistry and immunocomplex kinase assay approaches. Corneal epithelial wound healing was evaluated by a whole-eye organ culture model and by scratch-induced wound closure assay. Corneal epithelial layer was removed by using a corneal rust-ring-remover in wild-type and Plk3(-/-) mice. Wound healing was analyzed using a confocal imaging system. Cell growth was measured by MTT assays.

RESULTS

The effect of hypoxic stress on early stages of corneal epithelial wound healing was compared with other oxidative stresses, including UV, CoCl(2), and H(2)O(2) treatments. Hypoxic stress-induced delay of corneal epithelial wound healing was further evaluated in human corneal epithelial cells and in the corneas of wild-type and Plk3 knockout (Plk3(-/-)) mice. Hypoxic stress-induced Plk3 activation resulted in growth attenuation and delay of wound healing. Further evidence demonstrated that the increase in Plk3 activity in constitutively active Plk3-expressed cells significantly enhanced stress-induced delay of wound healing. In contrast, hypoxic stress-induced delay of wound healing was markedly diminished in the corneas of Plk3 deficient Plk3(-/-) mice.

CONCLUSIONS

These results provide for the first time important evidence that Plk3 plays a significant role in hypoxic stress-induced attenuation of cell growth and delay of corneal epithelial wound healing.

IL-17-mediated monocyte migration occurs partially through CC chemokine ligand 2/monocyte chemoattractant protein-1 induction

Rheumatoid arthritis (RA) is a chronic inflammatory disease that is mediated, in part, by proinflammatory factors produced by RA synovial tissue (ST) fibroblasts and macrophages, resulting in monocyte migration from the blood to the ST. To characterize the potential role of IL-17 in monocyte migration, RA synovial fibroblasts and macrophages were activated with IL-17 and examined for the expression of monocyte chemokines. The two potentially important monocyte chemoattractants identified were CCL20/MIP-3alpha and CCL2/MCP-1, which were significantly induced in RA synovial fibroblasts and macrophages. However, in vivo, only CCL2/MCP-1 was detectable following adenovirus IL-17 injection. We found that IL-17 induction of CCL2/MCP-1 was mediated by the PI3K, ERK, and JNK pathways in RA ST fibroblasts and by the PI3K and ERK pathways in macrophages. Further, we show that neutralization of CCL2/MCP-1 significantly reduced IL-17-mediated monocyte recruitment into the peritoneal cavity. We demonstrate that local expression of IL-17 in ankle joints was associated with significantly increased monocyte migration and CCL2/MCP-1 levels. Interestingly, we show that RA synovial fluids immunoneutralized for IL-17 and CCL2/MCP-1 have similar monocyte chemotaxis activity as those immunoneutralized for each factor alone. In short, CCL2/MCP-1 produced from cell types present in the RA joint, as well as in experimental arthritis, may be responsible, in part, for IL-17-induced monocyte migration; hence, these results suggest that CCL2/MCP-1 is a downstream target of IL-17 that may be important in RA.

Histone deacetylase inhibitors suppress inflammatory activation of rheumatoid arthritis patient synovial macrophages and tissue

Macrophages contribute significantly to the pathology of many chronic inflammatory diseases, including rheumatoid arthritis (RA), asthma, and chronic obstructive pulmonary disease. Macrophage activation and survival are tightly regulated by reversible acetylation and deacetylation of histones, transcription factors, and structural proteins. Although histone deacetylase (HDAC) inhibitors (HDACis) demonstrate therapeutic effects in animal models of chronic inflammatory disease, depressed macrophage HDAC activity in patients with asthma, chronic obstructive pulmonary disease, or RA may contribute to inflammation in these diseases, potentially contraindicating the therapeutic administration of HDACis. In this study, we directly examined whether HDACis could influence the activation of macrophages derived from the inflamed joints of patients with RA. We found that inhibition of class I/II HDACs or class III sirtuin HDACs potently blocked the production of IL-6 and TNF-alpha by macrophages from healthy donors and patients with RA. Two HDACis, trichostatin A and nicotinamide, selectively induced macrophage apoptosis associated with specific downregulation of the antiapoptotic protein Bfl-1/A1, and inflammatory stimuli enhanced the sensitivity of macrophages to HDACi-induced apoptosis. Importantly, inflammatory and angiogenic cytokine production in intact RA synovial biopsy explants was also suppressed by HDACis. Our study identifies redundant, but essential, roles for class I/II and sirtuin HDACs in promoting inflammation, angiogenesis, and cell survival in RA.

Molecular markers of preterm labor in the choriodecidua

Because relevant biochemical changes are known to begin at the choriodecidual interface some weeks before actual clinical onset of labor, we hypothesized that the preterm choriodecidua may display gene and protein expression patterns specific to preterm labor. Transcriptomic (microarray) and proteomic (2-dimensional gel electrophoresis [2DGE]) profiling methodologies were used to compare changes in choriodecidual tissue collected from women who delivered before 35 weeks of gestation following spontaneous preterm labor (n = 12) and gestation-matched nonlaboring controls (n = 7). Additionally, 2DGE was used to compare differences in protein expression during term and preterm labor and to construct a choriodecidual proteome map. Overall, expressed transcripts and proteins indicated active tissue remodeling independent of labor status and an association with inflammatory processes during labor. Spontaneous, infection-induced and abruption-associated preterm deliveries were each defined by distinct transcriptional profiles. Proteins osteoglycin and progesterone receptor component 2 (PGRMC2) were upregulated during term and preterm labor while galectin 1, annexin 3, annexin 5, and protein disulfide isomerase (PDI) were upregulated only during preterm labor, suggesting a probable association with the underlying pathology. Together, these results represent novel data that warrant further investigations to elucidate plausible causal relationships of these molecules with spontaneous preterm delivery.

BAX/BAK-independent mitoptosis during cell death induced by proteasome inhibition?

Proteasome inhibitors induce rapid death of cancer cells. We show that in epithelial cancer cells, such death is associated with dramatic and simultaneous up-regulation of several BH3-only proteins, including BIK, BIM, MCL-1S, NOXA, and PUMA, as well as p53. Elevated levels of these proteins seem to be the result of direct inhibition of their proteasomal degradation, induction of transcription, and active translation. Subsequent cell death is independent of BAX, and probably BAK, and proceeds through the intrinsic mitochondrial apoptosis pathway. We identify the cascade of molecular events responsible for cell death induced by a prototypical proteasome inhibitor, MG132, starting with rapid accumulation of BH3-only proteins in the mitochondria, proceeding through mitochondrial membrane permeabilization and subsequent loss of DeltaPsi(m), and leading to irreversible changes of mitochondrial ultrastructure, degradation of mitochondrial network, and detrimental impairment of crucial mitochondrial functions. Our results also establish a rationale for the broader use of proteasome inhibitors to kill apoptosis-resistant tumor cells that lack functional BAX/BAK proteins.

TNFalpha-induced macrophage death via caspase-dependent and independent pathways

Macrophages are the principal source of TNFalpha, yet they are highly resistant to TNFalpha-mediated cell death. Previously, employing in vitro differentiated human macrophages, we showed that following the inhibition of NF-kappaB, TNFalpha-induced caspase-8 activation contributes to DNA fragmentation but is not necessary for the loss of the inner mitochondrial transmembrane potential (DeltaPsim) or cell death. We here extend these observations to demonstrate that, when NF-kappaB is inhibited in macrophages, TNFalpha alters lysosomal membrane permeability (LMP). This results in the release of cathepsin B with subsequent loss of DeltaPsim and caspase-8 independent cell death. Interestingly, the cytoprotective, NF-kappaB-dependent protein A20 was rapidly induced in macrophages treated with TNFalpha. Ectopic expression of A20 in macrophages preserves LMP following treatment with TNFalpha, and as a result, mitochondrial integrity is safeguarded and macrophages are protected from cell death. These observations demonstrate that TNFalpha triggers both caspase 8-dependent and -independent cell death pathways in macrophages and identify a novel mechanism by which A20 protects these cells against both pathways.

Activation-induced degradation of FLIP(L) is mediated via the phosphatidylinositol 3-kinase/Akt signaling pathway in macrophages

Cellular FLIP (Flice-like inhibitory protein) is critical for the protection against death receptor-mediated cell apoptosis. In macrophages, FLIP long (FLIP(L)) and FLIP short (FLIP(S)) mRNA was induced by tumor necrosis factor (TNF) alpha, mediated through NF-kappaB. However, we observed TNFalpha reduced the protein level of FLIP(L), but not FLIP(S), at 1 and 2 h. Similar results were observed with lipopolysaccharide. The reduction of FLIP(L) by TNFalpha was not mediated by caspase 8, or through JNK or Itch, but was suppressed by inhibition of the phosphatidylinositol 3-kinase/Akt pathway employing chemical inhibitors, a dominant negative Akt-1, or Akt-1 small interfering RNA. The reduction of FLIP(L) resulted in the short term induction of caspase 8-like activity, which augmented NF-kappaB activation. A co-immunoprecipitation assay demonstrated that Akt-1 physically interacts with FLIP(L). Moreover, TNFalpha enhanced FLIP(L) serine phosphorylation, which was increased by activated Akt-1. Serine 273, a putative Akt-1 phosphorylation site in FLIP(L), was critical for the activation-induced reduction of FLIP(L). Thus, these observations document a novel mechanism where by TNFalpha facilitates the reduction of FLIP(L) protein, which is dependent on the phosphatidylinositol 3-kinase/Akt signaling.

Tumor necrosis factor alpha inhibits oxidative phosphorylation through tyrosine phosphorylation at subunit I of cytochrome c oxidase

Mitochondrial oxidative phosphorylation provides most cellular energy. As part of this process, cytochrome c oxidase (CcO) pumps protons across the inner mitochondrial membrane, contributing to the generation of the mitochondrial membrane potential, which is used by ATP synthase to produce ATP. During acute inflammation, as in sepsis, aerobic metabolism appears to malfunction and switches to glycolytic energy production. The pro-inflammatory cytokine tumor necrosis factor alpha (TNFalpha) has been shown to play a central role in inflammation. We hypothesized that TNFalpha-triggered cell signaling targets CcO, which is a central enzyme of the aerobic energy metabolism and can be regulated through phosphorylation. Using total bovine and murine hepatocyte homogenates TNFalpha treatment led to an approximately 60% reduction in CcO activity. In contrast, there was no direct effect of TNFalpha on CcO activity using isolated mitochondria and purified CcO, indicating that a TNFalpha-triggered intracellular signaling cascade mediates CcO inhibition. CcO isolated after TNFalpha treatment showed tyrosine phosphorylation on CcO catalytic subunit I and was approximately 50 and 70% inhibited at high cytochrome c concentrations in the presence of allosteric activator ADP and inhibitor ATP, respectively. CcO phosphorylation occurs on tyrosine 304 as demonstrated with a phosphoepitope-specific antibody. Furthermore, the mitochondrial membrane potential was decreased in H2.35 cells in response to TNFalpha. Concomitantly, cellular ATP was more than 35 and 64% reduced in murine hepatocytes and H2.35 cells. We postulate that an important contributor in TNFalpha-mediated pathologies, such as sepsis, is energy paucity, which parallels the poor tissue oxygen extraction and utilization found in such patients.

Activation of Polo-like kinase 3 by hypoxic stresses

Hypoxia/reoxygenation stress induces the activation of specific signaling proteins and activator protein 1 (AP-1) to regulate cell cycle regression and apoptosis. In the present study, we report that hypoxia/reoxygenation stress activates AP-1 by increasing c-Jun phosphorylation and DNA binding activity through activation of Polo-like-kinase 3 (Plk3) resulting in apoptosis. The specific effect of hypoxia/reoxygenation stress on Plk3 activation resulting in c-Jun phosphorylation was the opposite of UV irradiation-induced responses that are meanly independent on activation of the stress-induced JNK signaling pathway in human corneal epithelial (HCE) cells. The effect of hypoxia/reoxygenation stress-induced Plk3 activation on increased c-Jun phosphorylation and apoptosis was also mimicked by exposure of cells to CoCl(2). Hypoxia/reoxygenation activated Plk3 in HCE cells to directly phosphorylate c-Jun proteins at phosphorylation sites Ser-63 and Ser-73, and to increase DNA binding activity of c-Jun, detected by EMSA. Further evidence demonstrated that Plk3 and phospho-c-Jun were immunocolocalized in the nuclear compartment of hypoxia/reoxygenation stress-induced cells. Increased Plk3 activity by overexpression of wild-type and dominantly positive Plk3 enhanced the effect of hypoxia/reoxygenation on c-Jun phosphorylation and cell death. In contrast, knocking-down Plk3 mRNA suppressed hypoxia-induced c-Jun phosphorylation. Our results provide a new mechanism indicating that hypoxia/reoxygenation induces Plk3 activation instead of the JNK effect to directly phosphorylate and activate c-Jun, subsequently contributing to apoptosis in HCE cells.

HO-1 underlies resistance of AML cells to TNF-induced apoptosis

In human monocytes, tumor necrosis factor (TNF) induces a proinflammatory response. In NF-κB–inhibited monocytes, TNF stimulates cell death/apoptosis. In the present study, we analyzed the response of acute myeloid leukemia (AML) cells to TNF stimulation in conjunction with NF-κB inhibition. In all AML-derived cells tested, NF-κB–inhibited cells were resistant to TNF-induced apoptosis. Further investigation revealed that the cytoprotective gene heme oxygenase-1 (HO-1) was induced in NF-κB–inhibited AML cells in response to TNF stimulation, and HO-1 was responsible for the resistance of AML cells to the cytotoxic actions of TNF. Moreover, after transfection with HO-1 siRNA, the resistance to TNF-induced cell death signals of AML cells was removed. The HO-1 promoter region contains antioxidant-response elements that can bind the transcription factor NF-E2–related factor 2 (Nrf2). We further demonstrated that Nrf2 was activated by TNF under NF-κB–inhibited conditions, to play the major role in up-regulating HO-1 expression and ultimately the fate of AML cells. These results demonstrate a novel mechanism by which TNF-induced cell death is inhibited in AML cells through the induction of HO-1, via Nrf2 activation.