TNF and TNF-receptors: From mediators of cell death and inflammation to therapeutic giants - past, present and future

The effect of selected molecules influencing the detrimental host immune response on a course of rabies virus infection in a murine model

Rabies is invariably fatal, when post-exposure prophylaxis is administered after the onset of clinical symptoms. In many countries, rabies awareness is very low and the availability of post-exposure prophylaxis, as recommended by WHO guidelines, is very limited or non-existent, probably as a consequence of high cost. Therefore, new concepts for rabies therapy are needed. Innate immune mechanisms involving the production of pro-inflammatory cytokines and chemokines, activated after rabies infection, are thought to be involved in the neuropathogenesis of rabies. These mechanisms can contribute to a detrimental host response to the rabies virus (RABV) infection. The use of inhibitors of cytokines/chemokines are supposed to extend the survival of a sick individual. Inhibitors of TNF-α, IL-6 and MAPKs were used in RABV inoculated mice to define their influence on the survival time of rabid mice. The study demonstrated that all inhibitors extended mice survival, but at different rates. A log-rank test confirmed the statistically significant survival of mice treated with TNF-α (p = .0087) and MAPKs inhibitors (p = .0024). A delay in the time of onset of rabies was also recorded, in mice given TNF-α and MAPKs inhibitors. The highest virus load was found in the spinal cord and the lowest in the cortex, regardless of the experimental group. Significant TNF-α (p ≤ .0001) and IL-6 (p ≤ .0001) gene upregulation was observed in mice, as a consequence of RABV infection. Regarding MAPKs pathways, there was significant upregulation of the caspase 3 (p = .012, p = .0026) and Mcl-1 (p = .0348, p = .0153) genes, whereas significant downregulation of the cytochrome C (p ≤ .0001), Bcl2 (p = .0002, p = .0007) and JNK3 (p = .042) genes. Rabies pathogenesis is multifactorial, involving both virus and host influences on the course of the infection.

Toll-like receptors participate in Naegleria fowleri recognition

Naegleria fowleri is a protozoan that invades the central nervous system and causes primary amoebic meningoencephalitis. It has been reported that N. fowleri induces an important inflammatory response during the infection. In the present study, we evaluated the roles of Toll-like receptors in the recognition of N. fowleri trophozoites by human mucoepithelial cells, analyzing the expression and production of innate immune response mediators. After amoebic interactions with NCI-H292 cells, the expression and production levels of IL-8, TNF-α, IL-1β, and human beta defensin-2 were evaluated by RT-PCR, ELISA, immunofluorescence, and dot blot assays, respectively. To determine whether the canonical signaling pathways were engaged, we used different inhibitors, namely, IMG-2005 for MyD88 and BAY 11-7085 for the nuclear factor NFkB. Our results showed that the expression and production of the pro-inflammatory cytokines and beta defensin-2 were induced by N. fowleri mainly through the canonical TLR4 pathway in a time-dependent manner.

Lipid Peroxidation and Immune Biomarkers Are Associated with Major Depression and Its Phenotypes, Including Treatment-Resistant Depression and Melancholia

To examine immune-inflammatory and oxidative (I&O) biomarkers in major depression (MDD) and its related phenotypes, we recruited 114 well-phenotyped depressed patients and 50 healthy controls and measured serum levels of interleukin (IL)-1α, soluble IL-1 receptor antagonist (sIL-1RA), soluble IL-2 receptor (sIL-2R), soluble IL-6 receptor (sIL-6R), soluble tumor necrosis factor receptor 60 and 80 kDa (sTNF-R1/R2), and thiobarbituric acid reactive substances (TBARS). Obtained results indicate that MDD is characterized by increased sIL-1RA, sTNF-R1, and TBARS concentrations. Melancholic depression is associated with increased sIL-6R but lowered IL-1α levels. A current episode of depression is accompanied by significantly increased sIL-6R compared to the remitted state. Treatment-resistant depression (TRD) is accompanied by increased sIL-6R and TBARS but lowered sTNF-R2 levels compared to non-TRD patients. These immune markers are not significantly correlated with Hamilton Depression Rating Scale (HDRS), Montgomery-Asberg Depression Scale (MADRS), number episodes, or age at onset. Our findings show that increased sIL-1RA, sTNF-R1, and TBARS levels may be trait markers of depression, while increased sIL-6R levels may be a state marker of melancholia and an acute phase of depression. MDD is accompanied by increased lipid peroxidation and simultaneous activation of immune pathways, and the compensatory anti-inflammatory reflex system (CIRS). TRD is characterized by highly increased oxidative stress and probably increased TNFα and IL-6 trans-signalling. Novel treatments for major depression should target oxidative stress pathways, while new treatments for TRD should primary target lipid peroxidation and also activated immune-inflammatory pathways.

Antinflammatory and anticancer effects of terpenes from oily fractions of Teucruim alopecurus, blocker of IκBα kinase, through downregulation of NF-κB activation, potentiation of apoptosis and suppression of NF-κB-regulated gene expression

Teucrium alopecurus is an endemic plant limited to southern Tunisia. In the present study, the chemical composition, anticancer and nuclear factor-κB (NF-κB) inhibitory effects of Teucrium alopecurus leaf essential oil was investigated. The analysis of Teucrium alopecurus (TA-1) with Gas Chromatography-Mass Spectrometry (GC/MS) showed that α-Bisabolol, (+)-epi-Bicyclosesquiphellandrene and α-Cadinol, were found in relatively high amounts (16.16%, 15.40% and 8.52%, respectively). Cell viability was determined by 3-(4-5-dimethylthiazol-2-yl) 2-5-diphenyl-tetrazolium (MTT) assay. Cell cycle and apoptosis assay were determined by flow cytometry. TA-1 functions as an anticancer agent by triggering apoptosis potentiated by chemotherapeutic agents and TNF in human myeloid leukemia cells (KBM5) through a mechanism involving poly(ADP-ribose) polymerase (PARP) cleavage and initiator and effector caspases activation. Moreover, electrophoretic mobility shift assay (EMSA) revealed that TA-1 downregulated nuclear localization of NF-κB and its phosphorylation induced by TNF-α and this, allows the suppression of the degradation and phosphorylation of IκB and the inhibition of the phosphorylation of p65 phosphorylation and the p50-p65 heterodimer nuclear translocation, causing attenuation of NF-κB-regulated antiapoptotic (Survivin, Bcl-2, c-IAP1/2, Bcl-xL, Mcl-1, and cFLIP), invasion (ICAM1), metasatsis (MMP-9), and angiogenesis (VEGF) gene expression in KBM5; and finally reporter gene expression. Furthermore, treatment with essential oil and TNF-α suppressed the NF-κB DNA binding activity. Finally, the activation of nuclear factor-κB induced by different plasmids (TNFR1, TRADD, TRAF2, NIK, TAK1/TAB1, and IKKβ) was inhibited following treatment with TA-1. Overall, TA-1 inhibits NF-κB activation and further growth and proliferation of cancer cells.

Effects of specific egg yolk immunoglobulin on pan-drug-resistant Acinetobacter baumannii

With the growing emergence of pan-drug-resistant Acinetobacter baumannii (PDR-Ab) strains in clinical, new strategies for the treatment of PDR-Ab infections are urgently needed. Egg yolk immunoglobulin (IgY) as a convenient and inexpensive antibody has been widely applied to the therapy of infectious diseases. The aim of this study was to produce IgY specific to PDR-Ab and investigate its antibacterial effects in vitro and in vivo. IgYs specific to two PDR-Ab strains were produced by immunizing hens with formaldehyde inactivated PDR-Ab cells and isolated from yolks with a purity of 90% by water dilution, salt precipitations and ultrafiltration. IgYs showed high titers when subjected to an ELISA and inhibited the growth of PDR-Ab in a dose-dependent manner in liquid medium. Scanning electron microscopy assay showed structural modification and aggregation of PDR-Ab treated with specific IgYs. Freshly cultured PDR-Ab cells were nasally inhaled in BALB/c mice to induce acute pneumonia. The infected mice were intraperitoneally injected with specific IgYs using cefoperazone/sulbactam and dexamethasone as positive controls. The IgYs specific to PDR-Ab lowered the mortality of mice with PDR-Ab-induced acute pneumonia, decreased the level of TNF-α and IL-1β in serum and reduced inflammation in lung tissue. Specific IgY has the potential to be used as a new therapeutic approach for the treatment of A. baumannii-induced infections.

Misoprostol Inhibits Lipopolysaccharide-Induced Pro-inflammatory Cytokine Production by Equine Leukocytes

Pro-inflammatory cytokines including tumor necrosis factor α (TNFα), IL-1β, IL-6, and IL-8 are potent immune mediators that exacerbate multiple equine diseases such as sepsis and laminitis. Unfortunately, safe and effective cytokine-targeting therapies are lacking in horses; therefore, novel mechanisms of inhibiting cytokine production are critically needed. One potential mechanism for inhibiting cytokine synthesis is elevation of intracellular cyclic AMP (cAMP). In human leukocytes, intracellular cAMP production is induced by activation of E-prostanoid (EP) receptors 2 and 4. These receptors can be targeted by the EP2/4 agonist and prostaglandin E1 analog, misoprostol. Misoprostol is currently used as a gastroprotectant in horses but has not been evaluated as a cytokine-targeting therapeutic. Thus, we hypothesized that misoprostol treatment would inhibit pro-inflammatory cytokine production by lipopolysaccharide (LPS)-stimulated equine leukocytes in an in vitro inflammation model. To test this hypothesis, equine leukocyte-rich plasma (LRP) was collected from 12 healthy adult horses and used to model LPS-mediated inflammatory signaling. LRP was treated with varying concentrations of misoprostol either before (pretreated) or following (posttreated) LPS stimulation. LRP supernatants were assayed for 23 cytokines using an equine-specific multiplex bead immunoassay. Leukocytes were isolated from LRP, and leukocyte mRNA levels of four important cytokines were evaluated via RT-PCR. Statistical differences between treatments were determined using one-way RM ANOVA (Holm-Sidak post hoc testing) or Friedman's RM ANOVA on Ranks (SNK post hoc testing), where appropriate (p < 0.05, n = 3-6 horses). These studies revealed that misoprostol pre- and posttreatment inhibited LPS-induced TNFα and IL-6 protein production in equine leukocytes but had no effect on IL-8 protein. Interestingly, misoprostol pretreatment enhanced IL-1β protein synthesis following 6 h of LPS stimulation, while misoprostol posttreatment inhibited IL-1β protein production after 24 h of LPS stimulation. At the mRNA level, misoprostol pre- and posttreatment inhibited LPS-induced TNFα, IL-1β, and IL-6 mRNA production but did not affect IL-8 mRNA. These results indicate that misoprostol exerts anti-inflammatory effects on equine leukocytes when applied before or after a pro-inflammatory stimulus. However, the effects we observed were cytokine-specific and sometimes differed at the mRNA and protein levels. Further studies are warranted to establish the inhibitory effects of misoprostol on equine cytokine production in vivo.

Tumor necrosis factor superfamily ligand mRNA expression profiles differ between humans and mice during homeostasis and between various murine kidney injuries

BACKGROUND

Several tumour necrosis factor (TNF) based therapeutics have already been approved for human use and several others are emerging. Therefore, we determined the mRNA expression levels of the TNF superfamily ligands (TNFSF) - e.g. TNF-α, lymphotoxin (LT)-α, LT-β, Fas-L (CD95-L), TNF-related apoptosis-inducing ligand (TRAIL), TNF-related weak inducer of apoptosis (TWEAK), 4-1BBL, OX40-L (CD252) and amyloid precursor protein (APP) in healthy human and mouse solid organs.

METHODS

We used quantitative real time-PCR to analyse mRNA expression levels of TNFSF ligands. Murine models of acute ischemic renal injury, chronic oxalate nephropathy, and immune complex glomerulonephritis were used. Renal injury was assessed by PAS staining, and infiltrating immune cells were analysed by immunohistochemistry. Data was analysed using non-parametric ANOVA (non-parametric; Kruskal-Wallis test).

RESULTS

We observed significant differences in the mRNA expression levels of TNFSF ligands in human and mouse solid organs. Furthermore, we determined their mRNA expressions during acute and chronic kidney injuries in mice. Our data demonstrate that the mRNA expression levels of TNFSF vary depending on the type of tissue injury - for example, acute ischemic renal injury, chronic crystalline nephropathy, and immune complex glomerulonephritis. In addition, we observed that mRNA expressions of TNFSF ligands are differentially regulated during the course of a transient ischemic renal injury (IRI) and chronic kidney modelling. We observed that TNF-α, LT-β, and 4-1BBL were significantly upregulated during the progression of IRI and crystal-induced chronic kidney disease (CKD), whereas only 4-1BBL and TNF-α were significantly upregulated and LT-β was significantly downregulated during the progression of immune complex glomerulonephritis. The mRNA expression of Fas-L was higher during IRI whereas it decreased in a time dependent manner during the progression of crystal-induced CKD.

CONCLUSION

We conclude that the injury- and species-specific differences of TNFSF ligands must be considered in order to avoid the misinterpretation and wrong conclusions during data extrapolation between species.

Long non-coding RNA SeT and miR-155 regulate the Tnfα gene allelic expression profile

It is becoming increasingly appreciated that the non-coding genome may have a great impact on the regulation of chromatin structure and gene expression. The innate immune response can be mediated upon lipopolysaccharide stimulation of macrophages which leads to immediate transcriptional activation of early responsive genes including tumor necrosis factor alpha (Tnfα). The functional role of non-coding RNAs, such as lncRNAs and microRNAs, on the transcriptional activation of proinflammatory genes and the subsequent regulation of the innate immune response is still lacking mechanistic insights. In this study we wanted to unravel the functional role of the lncRNA SeT, which is encoded from the murine Tnfα gene locus, and miR-155 on the transcriptional regulation of the Tnfα gene. We utilized genetically modified mice harboring either a deletion of the SeT promoter elements or the mature miR-155 and studied the response of macrophages to lipopolysaccharide (LPS) stimulation. We found that decreased expression of the lncRNA SeT in murine primary macrophages resulted in increased mortality of mice challenged with LPS, which was corroborated by increased Tnfα steady state mRNA levels and a higher frequency of biallelically expressing macrophages. On the contrary, miR-155 deletion resulted in reduced Tnfα mRNA levels supported by a lower frequency of biallelically expressing macrophages upon stimulation with LPS. In both cases, in the absence of either lncRNA SeT or miR-155 we observed a deregulation of the Tnfα allele homologous pairing, previously shown to regulate the switch from mono- to bi-allelic gene expression. Although lncRNA SeT was not found to be a direct target of miR-155 its stability was increased upon miR-155 deletion. This study suggests a role of the non-coding genome in mediating Tnfα mRNA dosage control based on the regulation of homologous pairing of gene alleles and their subsequent biallelic expression.

NKG2D Signaling between Human NK Cells Enhances TACE-Mediated TNF-α Release

NK group 2 member D (NKG2D) is a strong NK cell-activating receptor, with engagement by ligands triggering granule release and cytokine production. The function of NKG2D signaling in NK cells has largely been studied in the context of engagement of the receptor by ligands expressed on the surface of target cells. We report that upon activation with IL-12, IL-15, and IL-18 human NK cells express NKG2D ligands of the UL16 binding protein family on the cell surface. NKG2D-ligand interaction between cytokine-stimulated NK cells increases the activity of the metalloprotease TNF-α-converting enzyme. This enhanced TNF-α-converting enzyme activity significantly increases the release of TNF-α and UL16 binding protein from the surface of the NK cells. These results demonstrate that NKG2D signaling is critical for maximal TNF-α release by NK cells. Further, they demonstrate a role for NKG2D-ligand interaction via homotypic NK cell contact in NK cell effector function.

Amyotrophic Lateral Sclerosis, a Multisystem Pathology: Insights into the Role of TNFα

Amyotrophic lateral sclerosis (ALS) is considered a multifactorial, multisystem disease in which inflammation and the immune system play important roles in development and progression. The pleiotropic cytokine TNFα is one of the major players governing the inflammation in the central nervous system and peripheral districts such as the neuromuscular and immune system. Changes in TNFα levels are reported in blood, cerebrospinal fluid, and nerve tissues of ALS patients and animal models. However, whether they play a detrimental or protective role on the disease progression is still not clear. Our group and others have recently reported opposite involvements of TNFR1 and TNFR2 in motor neuron death. TNFR2 mediates TNFα toxic effects on these neurons presumably through the activation of MAP kinase-related pathways. On the other hand, TNFR2 regulates the function and proliferation of regulatory T cells (Treg) whose expression is inversely correlated with the disease progression rate in ALS patients. In addition, TNFα is considered a procachectic factor with a direct catabolic effect on skeletal muscles, causing wasting. We review and discuss the role of TNFα in ALS in the light of its multisystem nature.

An Inflammatory Perspective on Necroptosis

Necroptosis (programmed necrosis) occurs in response to TNF, Fas, or TRAIL, as well as certain TLR ligands, when caspase activity required for apoptosis is blocked. Necroptosis is typically considered a highly pro-inflammatory mode of cell death, due to release of intracellular "danger signals" that promote inflammation. However, because most pro-necroptotic stimuli are intrinsically highly pro-inflammatory-due to their ability to initiate the synthesis of numerous cytokines and chemokines-the inflammatory consequences of necroptosis are complex. Here, we suggest that necroptosis might have anti-inflammatory effects in certain settings, through curbing excessive TNF- or TLR-induced inflammatory cytokine production.

Comparison of Diabetic and Non-diabetic Human Leukocytic Responses to Different Capsule Types of Klebsiella pneumoniae Responsible for Causing Pyogenic Liver Abscess

The major risk factor for Klebsiella liver abscess (KLA) is type 2 diabetes mellitus (DM), but the immunological mechanisms involved in the increased susceptibility are poorly defined. We investigated the responses of neutrophils and peripheral blood mononuclear cells (PBMCs) to hypervirulent Klebsiella pneumoniae (hvKP), the causative agent of KLA. DNA and myeloperoxidase levels were elevated in the plasma of KLA patients compared to uninfected individuals indicating neutrophil activation, but diabetic status had no effect on these neutrophil extracellular trap (NET) biomarkers in both subject groups. Clinical hvKP isolates universally stimulated KLA patient neutrophils to produce NETs ex vivo, regardless of host diabetic status. Ability of representative capsule types (K1, K2, and non-K1/K2 strains) to survive intra- and extra-cellular killing by type 2 DM and healthy neutrophils was subsequently examined. Key findings were: (1) type 2 DM and healthy neutrophils exhibited comparable total, phagocytic, and NETs killing against hvKP, (2) phagocytic and NETs killing were equally effective against hvKP, and (3) hypermucoviscous K1 and K2 strains were more resistant to total, phagocytic, and NETs killing compared to the non-mucoviscous, non-K1/K2 strain. The cytokine response and intracellular killing ability of type 2 DM as well as healthy PBMCs upon encounter with the different capsule types was also examined. Notably, the IL-12–IFNγ axis and its downstream chemokines MIG, IP-10, and RANTES were produced at slightly lower levels by type 2 DM PBMCs than healthy PBMCs in response to representative K1 and non-K1/K2 strains. Furthermore, type 2 DM PBMCs have a mild defect in its ability to control hvKP replication relative to healthy PBMCs. In summary, our work demonstrates that type 2 DM does not overtly impact neutrophil intra- and extra-cellular killing of hvKP, but may influence cytokine/chemokine production and intracellular killing by PBMCs.

Unlocking the NF-κB Conundrum: Embracing Complexity to Achieve Specificity

Transcription factors of the nuclear factor κB (NF-κB) family are central coordinating regulators of the host defence responses to stress, injury and infection. Aberrant NF-κB activation also contributes to the pathogenesis of some of the most common current threats to global human health, including chronic inflammatory diseases, autoimmune disorders, diabetes, vascular diseases and the majority of cancers. Accordingly, the NF-κB pathway is widely considered an attractive therapeutic target in a broad range of malignant and non-malignant diseases. Yet, despite the aggressive efforts by the pharmaceutical industry to develop a specific NF-κB inhibitor, none has been clinically approved, due to the dose-limiting toxicities associated with the global suppression of NF-κB. In this review, we summarise the main strategies historically adopted to therapeutically target the NF-κB pathway with an emphasis on oncology, and some of the emerging strategies and newer agents being developed to pharmacologically inhibit this pathway.

Biologics that inhibit the Th17 pathway and related cytokines to treat inflammatory disorders

INTRODUCTION

Advances in the understanding of TNF-α and IL-17 synergistic functions have recently led to the concept that patients who do not respond or who respond inadequately to TNF-α inhibitors may have IL-17-driven diseases, opening up the way for a new class of therapeutic development: Th17-inhibitors. Areas covered: In this review, the authors discuss the central role that the IL-23/Th17 axis plays in the pathogenesis of several inflammatory diseases, such as psoriasis, highlighting its position as a relevant therapeutic target. In particular, the authors start by giving a brief historical excursus on biologic agent development up until the success of TNF-α inhibitors, and continue with an overview of IL12/23 pathway inhibition. Next, they describe Th17 cell biology, focusing on the role of IL-17 in host defense and in human immune-inflammatory diseases, discussing the use and side effects of IL-17 inhibitors. Expert opinion: The IL-23/Th17 signaling pathway plays a central role in the pathogenesis of several inflammatory diseases, such as psoriasis. Recent data has demonstrated that biologics neutralizing IL-17 (ixekizumab, secukinumab) or its receptor (brodalumab) are highly effective with a positive safety profile in treating moderate to severe psoriasis, offering new treatment possibilities, especially for patients who do not respond adequately to anti-TNF-α therapies.

DOCK8 Drives Src-Dependent NK Cell Effector Function

Mutations in the dedicator of cytokinesis 8 (DOCK8) gene cause an autosomal recessive form of hyper-IgE syndrome, characterized by chronic immunodeficiency with persistent microbial infection and increased incidence of malignancy. These manifestations suggest a defect in cytotoxic lymphocyte function and immune surveillance. However, how DOCK8 regulates NK cell-driven immune responses remains unclear. In this article, we demonstrate that DOCK8 regulates NK cell cytotoxicity and cytokine production in response to target cell engagement or receptor ligation. Genetic ablation of DOCK8 in human NK cells attenuated cytokine transcription and secretion through inhibition of Src family kinase activation, particularly Lck, downstream of target cell engagement or NKp30 ligation. PMA/Ionomycin treatment of DOCK8-deficient NK cells rescued cytokine production, indicating a defect proximal to receptor ligation. Importantly, NK cells from DOCK8-deficient patients had attenuated production of IFN-γ and TNF-α upon NKp30 stimulation. Taken together, we reveal a novel molecular mechanism by which DOCK8 regulates NK cell-driven immunity.

Assessment of the involvement of the macrophage migration inhibitory factor-glucocorticoid regulatory dyad in the expression of matrix metalloproteinase-2 during periodontitis

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine and counter-regulator of endogenous glucocorticoids (GCs). It is implicated in acute and chronic inflammatory diseases. This study investigated the role of the MIF-GC regulatory dyad in the expression and release of matrix metalloproteinase-2 (MMP-2) during periodontitis, in vivo and in vitro. In a Mif-knockout (KO) mouse model of ligature-induced periodontitis, gingival tissues and blood were collected and analysed for levels of interleukin-6 (IL-6), MIF, MMP-2, and corticosterone. In addition, human gingival fibroblasts (HGFs) were tested for production of IL-6 and MMP-2 after stimulation with hydrocortisone (HC), MIF, tumour necrosis factor-alpha (TNF-α), or Fusobacterium nucleatum, a pathogen known to elicit immune responses during periodontitis. Wild-type (WT) mice showed a local and systemic increase of MIF levels during inflammation, which was confirmed by increased local IL-6 concentrations. Systemic GC levels were reduced in WT and Mif-KO mice during inflammation, with overall lower concentrations in Mif-KO mice. In vivo and in vitro, MMP-2 production was not dependent on MIF or inflammatory stimuli, but was inhibited by HC. Therefore, MIF does not appear to stimulate expression of MMP-2 in the gingival tissues, whereas GC upregulates MIF and downregulates MMP-2. Our findings further suggest that MIF may regulate systemic GC levels.

The role of 5-lipoxygenase in Aggregatibacter actinomycetemcomitans-induced alveolar bone loss

AIM

Leukotrienes (LTs) are pro-inflammatory lipid mediators formed by the enzyme 5-lipoxygenase (5-LO). The involvement of 5-LO metabolites in periodontal disease (PD) is not well defined. This study aimed to assess the role of 5-LO in experimental PD induced by Aggregatibacter actinomycetemcomitans (Aa).

MATERIAL AND METHODS

In vivo experiments were carried out using SV129 wild-type (WT) and 5-LO-deficient (5lo^-/- ) mice inoculated with Aa. Osteoclasts were stimulated in vitro with AaLPS in the presence or not of selective inhibitors of the 5-LO pathway, or LTB4 or platelet-activating factor (PAF), as PAF has already been shown to increase osteoclast activity.

RESULTS

In 5lo^-/- mice, there were no loss of alveolar bone and less TRAP-positive osteoclasts in periodontal tissues, after Aa inoculation, despite local production of TNF-α and IL-6. The differentiation and activity of osteoclasts stimulated with AaLPS were diminished in the presence of BLT1 antagonist or 5-LO inhibitor, but not in the presence of cysteinyl leukotriene receptor antagonist. The osteoclast differentiation induced by PAF was impaired by the BLT1 antagonism.

CONCLUSION

In conclusion, LTB4 but not CysLTs is important for Aa-induced alveolar bone loss. Overall, LTB4 affects osteoclast differentiation and activity and is a key intermediate of PAF-induced osteoclastogenesis.

Immunogenic Chemotherapy Sensitizes Renal Cancer to Immune Checkpoint Blockade Therapy in Preclinical Models

Background

Renal cell carcinoma (RCC) is among the most common malignant cancers of males worldwide. For advanced RCC patients, there still is no effective therapy. Immune checkpoint blockade therapies have shown benefits for many cancers, but previous clinical trials of immune checkpoint blockade therapies in RCC patients achieved only modest results.

Material/Methods

We explored the effects of combining chemotherapy with immune checkpoint blockade therapy in RCC xenograft mouse models. We also studied the potential mechanisms by which chemotherapy might enhance the efficacy of immune checkpoint blockade therapy, both in vitro and in vivo.

Results

Our results showed that many commonly used chemotherapy agents can induce immunogenic marker release in RCC cell lines. Importantly, the RCC xenograft mouse model mice who received the combination treatment of 5-fluorouracil (5-FU) and anti-programmed cell death-ligand 1 (PD-L1) antibodies (Abs) had longer survival times compared to those who received 5-FU or anti-PD-L1 Abs alone. Also, increased key cytokines that promote tumor immunity, such as IL-2, IFN-γ, and TNF-α, as well as tumor-infiltrating cytotoxic T cells, were also increased after the combination treatment.

Conclusions

We conclude that 5-FU can sensitize RCC to anti-PD-L1 treatment by releasing the immune suppression in the tumor microenvironment.

Development of a prodrug of hydantoin based TACE inhibitor

Our research on hydantoin based TNF-α converting enzyme (TACE) inhibitors led to fused bi-heteroaryl hydantoin series that demonstrate sub-nanomolar potency (Ki) as well as excellent activity in human whole blood (hWBA). However, lead compound 2 posed some formulation challenges which prevented it for further development. A prodrug approach was investigated to address this issue. The pivalate prodrug 3 can be formulated as stable neutral form and demonstrated improved DMPK properties when compared with parent compound.

Small molecules to the rescue: Inhibition of cytokine signaling in immune-mediated diseases

Cytokines are small, secreted proteins associated with the maintenance of immune homeostasis but also implicated with the pathogenesis of several autoimmune and inflammatory diseases. Biologic agents blocking cytokines or their receptors have revolutionized the treatment of such pathologies. Nonetheless, some patients fail to respond to these drugs or do not achieve complete remission. The signal transduction originating from membrane-bound cytokine receptors is an intricate network of events that lead to gene expression and ultimately regulate cellular functionality. Our understanding of the intracellular actions that molecules such as interleukins, interferons (IFNs) and tumor necrosis factor (TNF) set into motion has greatly increased in the past few years, making it possible to interfere with cytokines' signaling cascades. The Janus kinase (JAK)/signal transducer and activator of transcription (STAT), the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB), the mitogen activated protein kinase (MAPK) and the Phosphatidylinositol-3'-kinases (PI3K) pathways have all been intensively studied and key steps as well as molecules have been identified. These research efforts have led to the development of a new generation of small molecule inhibitors. Drugs capable of blocking JAK enzymatic activity or interfering with the proteasome-mediated degradation of intermediates in the NF-kB pathway have already entered the clinical arena confirming the validity of this approach. In this review, we have recapitulated the biochemical events downstream of cytokine receptors and discussed some of the drugs which have already been successfully utilized in the clinic. Moreover, we have highlighted some of the new molecules that are currently being developed for the treatment of immune-mediated pathologies and malignancies.

The structure-function relationship of disulfide bonds in etanercept

Etanercept is a TNFα receptor Fc fusion protein used for the treatment of rheumatic disease and psoriasis. Physicochemical and functional investigation of process fractions during development of the etanercept biosimilar GP2015 (Erelzi^®) revealed a correlation between reduced potency and incorrect disulfide bridging between specific cysteines in the receptor domain. This novel structure-function relationship was found to be the molecular basis for reduced potency in recent Enbrel^® batches, which exhibit higher levels of incorrect disulfide bridging. Interestingly, incorrect disulfide bridging was found to be reversible under serum-like redox conditions, restoring potency to normal levels. This redox dependent reversibility suggests that these variants are likely not relevant for clinical efficacy once the drug enters the bloodstream. Nonetheless, incorrect disulfide bridging in etanercept represents a new quality attribute that is critical for biopharmaceutical functionality and should thus be carefully monitored and controlled to guarantee patient safety.

Live endothelial cells imaged by Scanning Near-field Optical Microscopy (SNOM): capabilities and challenges

The scanning near-field optical microscopy (SNOM) shows a potential to study details of biological samples, since it provides the optical images of objects with nanometric spatial resolution (50-200 nm) and the topographic information at the same time. The goal of this work is to demonstrate the capabilities of SNOM in transmission configuration to study human endothelial cells and their morphological changes, sometimes very subtle, upon inflammation. Various sample preparations were tested for SNOM measurements and promising results are collected to show: 1) the influence of α tumor necrosis factor (TNF-α) on EA.hy 926 cells (measurements of the fixed cells); 2) high resolution images of various endothelial cell lines, i.e. EA.hy 926 and HLMVEC (investigations of the fixed cells in buffer environment); 3) imaging of live endothelial cells in physiological buffers. The study demonstrate complementarity of the SNOM measurements performed in air and in liquid environments, on fixed as well as on living cells. Furthermore, it is proved that the SNOM is a very useful method for analysis of cellular morphology and topography. Changes in the cell shape and nucleus size, which are the symptoms of inflammatory reaction, were noticed in TNF-α activated EA.hy 926 cells. The cellular structures of submicron size were observed in high resolution optical images of cells from EA.hy 926 and HLMVEC lines.

The totality-of-the-evidence approach to the development and assessment of GP2015, a proposed etanercept biosimilar

OBJECTIVE

The aim of this review is to describe the inherent variability that is natural to biologics and, using the proposed etanercept biosimilar (GP2015) as an example, provide details on the "totality-of-the-evidence" concept, whereby all physicochemical, biologic, preclinical, and clinical data for a biosimilar and reference medicine are evaluated in an iterative, stepwise manner and shown to be highly similar.

METHODS

This review was carried out by a search of published articles, reviews, abstracts and patents in PubMed/Medline and Google Scholar up to November 2016.

RESULTS

Analytical, functional, preclinical, and clinical data provide a comprehensive understanding of both GP2015 and reference etanercept, and demonstrate a high level of similarity between the two products in accordance with regulatory requirements. The totality of the evidence from all analyses and performed trials provides a robust scientific bridge between the biosimilar and clinical experience with the reference medicine, and is used to justify the use of the biosimilar in all indications for which the reference medicine is approved.

CONCLUSION

Biologic therapies have revolutionized the treatment of immune-mediated inflammatory diseases. The availability of biosimilars has the potential to improve patient access to biologic medicines and stimulate innovation. Physicians may be unfamiliar with the totality-of-the-evidence concept; therefore education and information on this unique approach to developing biosimilars is required to facilitate the use of biosimilars in clinical practice and allow physicians to make informed treatment decisions.

Experimental method and statistical analysis to fit tumor growth model using SPECT/CT imaging: a preclinical study

BACKGROUND

Over the last decade, several theoretical tumor-models have been developed to describe tumor growth. Oncology imaging is performed using various modalities including computed tomography (CT), magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT) and fluorodeoxyglucose-positron emission tomography (FDG-PET). Our goal is to extract useful, otherwise hidden, quantitative biophysical parameters (such as growth-rate, tumor-necrotic-factor, etc.) from these serial images of tumors by fitting mathematical models to images. These biophysical features are intrinsic to the tumor types and specific to the study-subject, and expected to add valuable information on the tumor containment or spread and help treatment plans. Thus, fitting realistic but practical models and assessing parameter-errors and degree of fit is important.

METHODS

We implemented an existing theoretical ode-compartment model and variants and applied them for the first time, in vivo. We developed an inversion algorithm to fit the models for tumor growth for simulated as well as in vivo experimental data. Serial SPECT/CT scans of mice breast-tumors were acquired, and SPECT data was used to segment the proliferating-layers of tumors.

RESULTS

Results of noisy data simulation and inversion show that 5 out of 7 parameters were recovered to within 4.3% error. In particular, tumor "growth-rate" parameter was recovered to 0.07% error. For model fitting to in vivo mice-tumors, regression analysis on the P-layer volume showed R² of 0.99 for logistic and Gompertzian while surface area model yielded R²=0.96. For the necrotic layer the R² values were 0.95, 0.93 and 0.94 respectively for surface-area, logistic and Gompertzian. The Akaike Information Criterion (AIC) weights of the models (giving their relative probability of being the best Kullback-Leibler (K-L) model among the set of candidate models) were ~0, 0.43 and 0.57 for surface-area, logistic and Gompertzian models.

CONCLUSIONS

Model-fitting to mice tumor studies demonstrates feasibility of applying the models to in vivo imaging data to extract features. Akaike information criterion (AIC) evaluations show Gompertzian or logistic growth model fits in vivo breast-tumors better than surface-area based growth model.

Systems-based approach to examine the cytokine responses in primary mouse lung macrophages infected with low pathogenic avian Influenza virus circulating in South East Asia

Background

Influenza A virus (IAV) is a major public health concern, being responsible for the death of approximately half a million people each year. Zoonotic transmissions of the virus from swine and avian origin have occurred in the past, and can potentially lead to the emgergence of new IAV stains in future pandemics. Pulmonary macrophages have been implicated in disease severity in the lower airway, and understanding the host response of macrophages infected with avian influenza viruses should provide new therapeutic strategies.

Results

We used a systems-based approach to investigate the transcriptome response of primary murine lung macrophages (PMФ) infected with the mouse-adapted H1N1/WSN virus and low pathogenic avian influenza (LPAI) viruses H5N2 and H5N3. The results showed that the LPAI viruses H5N2 and H5N3 can infect PMФ with similar efficiency to the H1N1/WSN virus. While all viruses induced antiviral responses, the H5N3 virus infection resulted in higher expression levels of cytokines and chemokines associated with inflammatory responses.

Conclusions

The LPAI H5N2 and H5N3 viruses are able to infect murine lung macrophages. However, the H5N3 virus was associated with increased expression of pro-inflammatory mediators. Although the H5N3 virus it is capable of inducing high levels of cytokines that are associated with inflammation, this property is distinct from its inability to efficiently replicate in a mammalian host.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-3803-6) contains supplementary material, which is available to authorized users.

Antigen delivery to dendritic cells shapes human CD4+ and CD8+ T cell memory responses to Staphylococcus aureus

Intracellular persistence of Staphylococcus aureus favors bacterial spread and chronic infections. Here, we provide evidence for the existence of human CD4⁺ and CD8⁺ T cell memory against staphylococcal antigens. Notably, the latter could provide a missing link in our understanding of immune control of intracellular S. aureus. The analyses showed that pulsing of monocyte-derived dendritic cells (MoDC) with native staphylococcal protein antigens induced release of Th2-associated cytokines and mediators linked to T regulatory cell development (G-CSF, IL-2 and IL-10) from both CD4⁺ and CD8⁺ T cells, thus revealing a state of tolerance predominantly arising from preformed memory T cells. Furthermore, G-CSF was identified as a suppressor of CD8⁺ T cell-derived IFNγ secretion, thus confirming a tolerogenic role of this cytokine in the regulation of T cell responses to S. aureus. Nevertheless, delivery of in vitro transcribed mRNA-encoded staphylococcal antigens triggered Th1-biased responses, e.g. IFNγ and TNF release from both naïve and memory T cells. Collectively, our data highlight the potential of mRNA-adjuvanted antigen presentation to enable inflammatory responses, thus overriding the existing Th2/Treg-biased memory T cell response to native S. aureus antigens.

Staphylococcus aureus is deemed one of the most important nosocomial pathogens but, to date, there are no safe and protective vaccines. In this study we investigate the nature of the preformed T cell response to S. aureus antigens in healthy donors. Our data reveal that CD4⁺ and—so far not described—CD8⁺ T cell memory responses against native staphylococcal antigens exist but are skewed towards minimizing inflammation and promoting tolerance. The T cell response to staphylococcal antigens is characterized by the secretion of typical Th2 cytokines such as IL-5 and IL-13 and mediators associated with formation of T regulatory cells. Most importantly, G-CSF suppresses IFNγ release from pre-existent memory T cells. However, our data reveal that the use of mRNA-encoded antigens to trigger S. aureus-specific T cell responses bears the potential to override the tolerogenic bias. It favors TNF- and IFNγ-releasing T cells and may, thus, represent an innovative tool in prophylactic and therapeutic vaccine development.

Tumor necrosis factor α Inhibition for Alzheimer's Disease

Tumor necrosis factor α (TNF-α) plays a central role in the pathophysiology of Alzheimer's disease (AD). Food and Drug Administration-approved biologic TNF-α inhibitors are thus a potential treatment for AD, but they do not cross the blood-brain barrier. In this short review, we discuss the involvement of TNF-α in AD, challenges associated with the development of existing biologic TNF-α inhibitors for AD, and potential therapeutic strategies for targeting TNF-α for AD therapy.

Tissue-Intrinsic Tumor Hotspots: Terroir for Tumorigenesis

Epithelial tissues are highly organized systems with a remarkable homeostatic ability to maintain morphology through regulation of cellular proliferation and tissue integrity. This robust self-organizing system is progressively disrupted during tumor development. Recent studies of conserved tumor-suppressor genes in Drosophila showed how protumor cells deviate from the robustly organized tissue microenvironment to take the first steps into becoming aggressive tumors. Here we review the 'tumor hotspot' hypothesis that explains how the tissue-intrinsic local microenvironment has a pivotal role in the initial stage of tumorigenesis in Drosophila epithelia and discuss comparable mechanisms in mammalian tissues.

CNS Demyelination with TNF-α Blockers

Tumor necrosis factor-α (TNF-α) blockers are a popular therapeutic choice in a number of inflammatory diseases. Thus far, five TNF- α blockers have been approved for clinical use (etanercept, infliximab, adalimumab, golimumab. and certolizumab). Despite being considered relatively safe, serious side effects associated with immune suppression have been reported, including central and peripheral nervous system (CNS) demyelinating disorders. It is still elusive whether these events are mere coincidence or a side effect of anti-TNF-α use. In this paper, we review the published case reports of CNS demyelination associated with anti-TNF-α therapy and present the follow-up of our 4 previously reported patients who developed neurologic symptoms suggestive of CNS demyelination after having received anti-TNF-α treatment. We also discuss the possible role of TNF-α blockers in demyelination.

Biglycan- and Sphingosine Kinase-1 Signaling Crosstalk Regulates the Synthesis of Macrophage Chemoattractants

In its soluble form, the extracellular matrix proteoglycan biglycan triggers the synthesis of the macrophage chemoattractants, chemokine (C-C motif) ligand CCL2 and CCL5 through selective utilization of Toll-like receptors (TLRs) and their adaptor molecules. However, the respective downstream signaling events resulting in biglycan-induced CCL2 and CCL5 production have not yet been defined. Here, we show that biglycan stimulates the production and activation of sphingosine kinase 1 (SphK1) in a TLR4- and Toll/interleukin (IL)-1R domain-containing adaptor inducing interferon (IFN)-β (TRIF)-dependent manner in murine primary macrophages. We provide genetic and pharmacological proof that SphK1 is a crucial downstream mediator of biglycan-triggered CCL2 and CCL5 mRNA and protein expression. This is selectively driven by biglycan/SphK1-dependent phosphorylation of the nuclear factor NF-κB p65 subunit, extracellular signal-regulated kinase (Erk)1/2 and p38 mitogen-activated protein kinases. Importantly, in vivo overexpression of soluble biglycan causes Sphk1-dependent enhancement of renal CCL2 and CCL5 and macrophage recruitment into the kidney. Our findings describe the crosstalk between biglycan- and SphK1-driven extracellular matrix- and lipid-signaling. Thus, SphK1 may represent a new target for therapeutic intervention in biglycan-evoked inflammatory conditions.

OX40: Structure and function - What questions remain?

OX40 is a type 1 transmembrane glycoprotein, reported nearly 30 years ago as a cell surface antigen expressed on activated T cells. Since its discovery, it has been validated as a bone fide costimulatory molecule for T cells and member of the TNF receptor family. However, many questions still remain relating to its function on different T cell sub-sets and with recent interest in its utility as a target for antibody-mediated immunotherapy, there is a growing need to gain a better understanding of its biology. Here, we review the expression pattern of OX40 and its ligand, discuss the structure of the receptor:ligand interaction, the downstream signalling it can elicit, its function on different T cell subsets and how antibodies might engage with it to provide effective immunotherapy.

Transient inflammatory response mediated by interleukin-1β is required for proper regeneration in zebrafish fin fold

Cellular responses to injury are crucial for complete tissue regeneration, but their underlying processes remain incompletely elucidated. We have previously reported that myeloid-defective zebrafish mutants display apoptosis of regenerative cells during fin fold regeneration. Here, we found that the apoptosis phenotype is induced by prolonged expression of interleukin 1 beta (il1b). Myeloid cells are considered to be the principal source of Il1b, but we show that epithelial cells express il1b in response to tissue injury and initiate the inflammatory response, and that its resolution by macrophages is necessary for survival of regenerative cells. We further show that Il1b plays an essential role in normal fin fold regeneration by regulating expression of regeneration-induced genes. Our study reveals that proper levels of Il1b signaling and tissue inflammation, which are tuned by macrophages, play a crucial role in tissue regeneration.

DOI:http://dx.doi.org/10.7554/eLife.22716.001

Animals and other multicellular organisms all have at least some ability to regenerate lost or wounded tissues. Zebrafish are particularly good at this to the extent that they can replace damaged or lost body parts with exact replicas of the originals. In 2015, a team of researchers found that some mutant zebrafish that lack blood cells including immune cells are unable to regenerate lost tissues. This is because the cells that are primed to regenerate die instead, but it was not clear why this happens.

Many immune cells have roles in fighting infection and in responding to tissue damage.When a tissue is damaged, the area often becomes inflamed as white blood cells called macrophages flock to the damaged area to protect it from infection and remove damaged cells.

Hasegawa et al. – who include several researchers involved in the 2015 study – used genetic approaches to investigate the role of inflammation in tissue regeneration in zebrafish. The experiments show that several genes involved in inflammation – including one called interleukin 1b – were active over longer periods of time in the mutant fish compared with normal zebrafish. The gene produces a signal protein and this prolonged activity causes the primed regenerative cells to die. However, the cells can survive if interleukin 1b activity is quickly suppressed by macrophages. The experiments also show that, in order for tissues to regenerate properly, interleukin 1b needs to be active for only a short period of time.

The findings reveal that some inflammation is needed for tissues to regenerate, but that a more severe inflammatory response can block the process. A future challenge will be to identify the signals that macrophages produce to suppress inflammation to allow tissues to regenerate. These anti-inflammatory signals may have the potential to be used as drugs to cure chronic inflammatory diseases and boost tissue regeneration potential in humans.

DOI:http://dx.doi.org/10.7554/eLife.22716.002

Oxaliplatin and Infliximab Combination Synergizes in Inducing Colon Cancer Regression

BACKGROUND Colon cancer is one of the most common malignant cancers and causes millions of deaths each year. There are still no effective treatments for colon cancer patients who are at advanced stage. Tumor necrosis factor-alpha (TNF-α) might be a good therapy target due to its widely-accepted roles in regulating multiple important biological processes, especially in promoting inflammation. MATERIAL AND METHODS We evaluated the expression of TNF-α in 108 human colon cancer tissue samples and 2 colon cancer cell lines (CT26 and HCT116), and analyzed its prognostic values. Further, we explored the roles and mechanism of anti-TNF-α treatment in combination with chemotherapy in vitro and in vivo. RESULTS We found that TNF-α was highly expressed in colon cancer cell lines. The survival analysis and Cox regression analysis indicated that high TNF-α was an independent adverse prognosticator of colon cancer. In addition, anti-TNF-α treatment enhanced the effects of chemotherapy in the xenograft mouse model through inducing ADCC and CDC effects. CONCLUSIONS We conclude that TNF-α is an independent adverse prognosticator of colon cancer, and anti-TNF-α might benefit colon cancer patients.

The Molecular Basis for the Lack of Inflammatory Responses in Mouse Embryonic Stem Cells and Their Differentiated Cells

We reported previously that mouse embryonic stem cells do not have a functional IFN-based antiviral mechanism. The current study extends our investigation to the inflammatory response in mouse embryonic stem cells and mouse embryonic stem cell-differentiated cells. We demonstrate that LPS, TNF-α, and viral infection, all of which induce robust inflammatory responses in naturally differentiated cells, failed to activate NF-κB, the key transcription factor that mediates inflammatory responses, and were unable to induce the expression of inflammatory genes in mouse embryonic stem cells. Similar results were obtained in human embryonic stem cells. In addition to the inactive state of NF-κB, the deficiency in the inflammatory response in mouse embryonic stem cells is also attributed to the lack of functional receptors for LPS and TNF-α. In vitro differentiation can trigger the development of the inflammatory response mechanism, as indicated by the transition of NF-κB from its inactive to active state. However, a limited response to TNF-α and viral infection, but not to LPS, was observed in mouse embryonic stem cell-differentiated fibroblasts. We conclude that the inflammatory response mechanism is not active in mouse embryonic stem cells, and in vitro differentiation promotes only partial development of this mechanism. Together with our previous studies, the findings described in this article demonstrate that embryonic stem cells are fundamentally different from differentiated somatic cells in their innate immunity, which may have important implications in developmental biology, immunology, and embryonic stem cell-based regenerative medicine.

Unsaturated lipid bodies as a hallmark of inflammation studied by Raman 2D and 3D microscopy

Endothelial HMEC-1 cells incubated with pro-inflammatory cytokine TNF-α for 6 and 24 hours were studied as a model of inflammation using Raman imaging. Striking changes in distribution, composition and concentration of cellular lipids were observed after exposure to TNF-α compared to the control. In particular, 3D Raman imaging revealed a significant increase in the amount of lipid entities formed under inflammation. Lipid bodies were randomly distributed in the cytoplasm and two types of droplets were assembled: more saturated one, in spectral characteristics resembling phosphatidylcholine and saturated cholesteryl esters, observed also in the control, and highly unsaturated one, containing also cholesterols, being a hallmark of inflamed cells. The statistical analysis showed that the number of lipid bodies was significantly dependent on the exposure time to TNF-α. Overall, observed formation of unsaturated lipid droplets can be directly correlated with the increase in production of prostacyclins - endogenous inflammation mediators.

Caspase-8: not so silently deadly

Apoptosis is a caspase-dependent programmed form of cell death, which is commonly believed to be an immunologically silent process, required for mammalian development and maintenance of cellular homoeostasis. In contrast, lytic forms of cell death, such as RIPK3- and MLKL-driven necroptosis, and caspase-1/11-dependent pyroptosis, are postulated to be inflammatory via the release of damage associated molecular patterns (DAMPs). Recently, the function of apoptotic caspase-8 has been extended to the negative regulation of necroptosis, the cleavage of inflammatory interleukin-1β (IL-1β) to its mature bioactive form, either directly or via the NLRP3 inflammasome, and the regulation of cytokine transcriptional responses. In view of these recent advances, human autoinflammatory diseases that are caused by mutations in cell death regulatory machinery are now associated with inappropriate inflammasome activation. In this review, we discuss the emerging crosstalk between cell death and innate immune cell inflammatory signalling, particularly focusing on novel non-apoptotic functions of caspase-8. We also highlight the growing number of autoinflammatory diseases that are associated with enhanced inflammasome function.