Induction of beta 2-interferon by tumor necrosis factor: a homeostatic mechanism in the control of cell proliferation

Interleukin-6: obstacles to targeting a complex cytokine in critical illness

Circulating concentrations of the pleiotropic cytokine interleukin-6 (IL-6) are known to be increased in pro-inflammatory critical care syndromes, such as sepsis and acute respiratory distress syndrome. Elevations in serum IL-6 concentrations in patients with severe COVID-19 have led to renewed interest in the cytokine as a therapeutic target. However, although the pro-inflammatory properties of IL-6 are widely known, the cytokine also has a series of important physiological and anti-inflammatory functions. An adequate understanding of the complex processes by which IL-6 signalling occurs is crucial for the correct interpretation of IL-6 concentrations in the blood or lung, the use of IL-6 as a critical care biomarker, or the design of effective anti-IL-6 strategies. Here, we outline the role of IL-6 in health and disease, explain the different types of IL-6 signalling and their contribution to the net biological effect of the cytokine, describe the approaches to IL-6 inhibition that are currently available, and discuss implications for the future use of treatments such as tocilizumab in the critical care setting.

A cut above the rest: oxidative stress in chronic wounds and the potential role of polyphenols as therapeutics

OBJECTIVES

The pathophysiology of chronic wounds typically involves redox imbalance and inflammation pathway dysregulation, often with concomitant microbial infection. Endogenous antioxidants such as glutathione and tocopherols are notably reduced or absent, indicative of significant oxidative imbalance. However, emerging evidence suggests that polyphenols could be effective agents for the amelioration of this condition. This review aims to summarise the current state of knowledge surrounding redox imbalance in the chronic wound environment and the potential use of polyphenols for the treatment of chronic wounds.

KEY FINDINGS

Polyphenols provide a multi-faceted approach towards the treatment of chronic wounds. Firstly, their antioxidant activity allows direct neutralisation of harmful free radicals and reactive oxygen species, assisting in restoring redox balance. Upregulation of pro-healing and anti-inflammatory gene pathways and enzymes by specific polyphenols further acts to reduce redox imbalance and promote wound healing actions, such as proliferation, extracellular matrix deposition and tissue remodelling. Finally, many polyphenols possess antimicrobial activity, which can be beneficial for preventing or resolving infection of the wound site.

SUMMARY

Exploration of this diverse group of natural compounds may yield effective and economical options for the prevention or treatment of chronic wounds.

Re-Examining the Role of TNF in MS Pathogenesis and Therapy

Multiple sclerosis (MS) is a common neurological disorder of putative autoimmune origin. Clinical and experimental studies delineate abnormal expression of specific cytokines over the course of the disease. One major cytokine that has been shown to play a pivotal role in MS is tumor necrosis factor (TNF). TNF is a pleiotropic cytokine regulating many physiological and pathological functions of both the immune system and the central nervous system (CNS). Convincing evidence from studies in human and experimental MS have demonstrated the involvement of TNF in various pathological hallmarks of MS, including immune dysregulation, demyelination, synaptopathy and neuroinflammation. However, due to the complexity of TNF signaling, which includes two-ligands (soluble and transmembrane TNF) and two receptors, namely TNF receptor type-1 (TNFR1) and type-2 (TNFR2), and due to its cell- and context-differential expression, targeting the TNF system in MS is an ongoing challenge. This review summarizes the evidence on the pathophysiological role of TNF in MS and in different MS animal models, with a special focus on pharmacological treatment aimed at controlling the dysregulated TNF signaling in this neurological disorder.

A linear prognostic score based on the ratio of interleukin-6 to interleukin-10 predicts outcomes in COVID-19

BACKGROUND

Prognostic tools are required to guide clinical decision-making in COVID-19.

METHODS

We studied the relationship between the ratio of interleukin (IL)-6 to IL-10 and clinical outcome in 80 patients hospitalized for COVID-19, and created a simple 5-point linear score predictor of clinical outcome, the Dublin-Boston score. Clinical outcome was analysed as a three-level ordinal variable ("Improved", "Unchanged", or "Declined"). For both IL-6:IL-10 ratio and IL-6 alone, we associated clinical outcome with a) baseline biomarker levels, b) change in biomarker level from day 0 to day 2, c) change in biomarker from day 0 to day 4, and d) slope of biomarker change throughout the study. The associations between ordinal clinical outcome and each of the different predictors were performed with proportional odds logistic regression. Associations were run both "unadjusted" and adjusted for age and sex. Nested cross-validation was used to identify the model for incorporation into the Dublin-Boston score.

FINDINGS

The 4-day change in IL-6:IL-10 ratio was chosen to derive the Dublin-Boston score. Each 1 point increase in the score was associated with a 5.6 times increased odds for a more severe outcome (OR 5.62, 95% CI -3.22-9.81, P = 1.2 × 10^-9). Both the Dublin-Boston score and the 4-day change in IL-6:IL-10 significantly outperformed IL-6 alone in predicting clinical outcome at day 7.

INTERPRETATION

The Dublin-Boston score is easily calculated and can be applied to a spectrum of hospitalized COVID-19 patients. More informed prognosis could help determine when to escalate care, institute or remove mechanical ventilation, or drive considerations for therapies.

FUNDING

Funding was received from the Elaine Galwey Research Fellowship, American Thoracic Society, National Institutes of Health and the Parker B Francis Research Opportunity Award.

Role of myokines in the development of skeletal muscle insulin resistance and related metabolic defects in type 2 diabetes

Due to its mass, skeletal muscle is the major site of glucose uptake and an important tissue in the development of type 2 diabetes (T2D). Muscles of patients with T2D are affected with insulin resistance and mitochondrial dysfunction, which result in impaired glucose and fatty acid metabolism. A well-established method of managing the muscle metabolic defects occurring in T2D is physical exercise. During exercise, muscles contract and secrete factors called myokines which can act in an autocrine/paracrine fashion to improve muscle energy metabolism. In patients with T2D, plasma levels as well as muscle levels (mRNA and protein) of some myokines are upregulated, while others are downregulated. The signalling pathways of certain myokines are also altered in skeletal muscle of patients with T2D. Taken together, these findings suggest that myokine secretion is an important factor contributing to the development of muscle metabolic defects during T2D. It is also of interest considering that lack of physical activity is closely linked to the occurrence of this disease. The causal relationships between sedentary behavior, factors secreted by skeletal muscle at rest and during contraction and the development of T2D remain to be elucidated. Many myokines shown to influence muscle energy metabolism still have not been characterized in the context of T2D in skeletal muscle specifically. The purpose of this review is to highlight what is known and what remains to be determined regarding myokine secretion in patients with T2D to uncover potential therapeutic targets for the management of this disease.

Safety evaluation of adalimumab in immune-mediated inflammatory disorders: a rheumatological point of view

INTRODUCTION

Immune-mediated inflammatory disorders (IMIDs) are systemic conditions which arise secondary to complex immune mechanism defects and can affect many organs. While previous therapies based on steroids and immunosuppressive agents had a poor risk/benefit balance, TNFα-specific inhibitors such as adalimumab have revolutionized the course of many diseases and patient outcomes. However, concerns were raised regarding the increased risk of infectious diseases and neoplasia due to potential prospective loss of immune control. This is especially true when considering that IMIDs concerns elderly/frail populations, with multiple co-morbidities, organ damage and often long-term steroid therapy. Areas covered: Now prescribed for more than 15 years for a diverse range of indications, long-term data highlighting the efficacy and safety are available and led to recommendations for the daily practice that will be discussed. Expert opinion: The efficacy of adalimumab changed the therapeutic paradigm of many diseases. Its tolerance is good and it is the most widely prescribed therapy in IMIDs. It is now the standard of care arm in head to head trials. In the long term, adalimumab dominant role might be weakened by more targeted therapies but its varied indications among IMIDs should secure its position as an important tool in our future practice.

Particulate Matter Air Pollution: Effects on the Cardiovascular System

Air pollution is a complex mixture of gaseous and particulate components, each of which has detrimental effects on human health. While the composition of air pollution varies greatly depending on the source, studies from across the world have consistently shown that air pollution is an important modifiable risk factor for significantly increased morbidity and mortality. Moreover, clinical studies have generally shown a greater impact of particulate matter (PM) air pollution on health than the gaseous components. PM has wide-ranging deleterious effects on human health, particularly on the cardiovascular system. Both acute and chronic exposure to PM air pollution is associated with increased risk of death from cardiovascular diseases including ischemic heart disease, heart failure, and ischemic/thrombotic stroke. Particulate matter has also been shown to be an important endocrine disrupter, contributing to the development of metabolic diseases such as obesity and diabetes mellitus, which themselves are risk factors for cardiovascular disease. While the epidemiological evidence for the deleterious effects of PM air pollution on health is increasingly accepted, newer studies are shedding light on the mechanisms by which PM exerts its toxic effects. A greater understanding of how PM exerts toxic effects on human health is required in order to prevent and minimize the deleterious health effects of this ubiquitous environmental hazard. Air pollution is a growing public health problem and mortality due to air pollution is expected to double by 2050. Here, we review the epidemiological evidence for the cardiovascular effects of PM exposure and discuss current understanding about the biological mechanisms, by which PM exerts toxic effects on cardiovascular system to induce cardiovascular disease.

Involvement of Interleukin-6 in the Autocrine Stimulation of Chronic Lymphocytic Leukemia B Cells by Tumor Necrosis Factor

Tumor necrosis factor α (TNFα) acts as an autocrine growth factor in chronic B cell malignancies. TNF also induces production of interleukin 6 (IL-6) which stimulates B cell growth and differentiation. We have previously demonstrated increased TNFα production by (Rai) stage 0 chronic lymphocytic leukemia (B-CLL) cells and the absence of TNF production by cells from stage IV patients. In an attempt to elucidate a possible role for TNF in the malignant progression of B-CLL we investigated the possibility of IL-6 involvment in the stimulatory action of TNF on B-CLL cells. We observed that: (1) the in vitro proliferative response of B-CLL cells to recombinant human (rh)THFα was consistently inhibited by a monoclonal antibody (MoAb) against IL-6, (2) the release of IL-6 by B-CLL cells could be augmented by rhTNFα, (3) no differences were detected in the foregoing parameters between stage 0 and stage IV-derived cells and (4) despite the inhibitory action of an anti-IL-6 MoAb on the TNF-induced proliferative response of B-CLL cells, IL-6 receptor expression was undetectable in these cells. Although these findings are suggestive of an autocrine or paracrine mechanism involving TNF and IL-6, the importance of the release and action of these cytokines in the regulation of B-CLL cell growth and malignant progression still remains to be elucidated.

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

Tumor Necrosis Factor (TNF), initially known for its tumor cytotoxicity, is a potent mediator of inflammation, as well as many normal physiological functions in homeostasis and health, and anti-microbial immunity. It also appears to have a central role in neurobiology, although this area of TNF biology is only recently emerging. Here, we review the basic biology of TNF and its normal effector functions, and discuss the advantages and disadvantages of therapeutic neutralization of TNF - now a commonplace practice in the treatment of a wide range of human inflammatory diseases. With over ten years of experience, and an emerging range of anti-TNF biologics now available, we also review their modes of action, which appear to be far more complex than had originally been anticipated. Finally, we highlight the current challenges for therapeutic intervention of TNF: (i) to discover and produce orally delivered small molecule TNF-inhibitors, (ii) to specifically target selected TNF producing cells or individual (diseased) tissue targets, and (iii) to pre-identify anti-TNF treatment responders. Although the future looks bright, the therapeutic modulation of TNF now moves into the era of personalized medicine with society's challenging expectations of durable treatment success and of achieving long-term disease remission.

Interleukin-6 and its receptors: a highly regulated and dynamic system

Interleukin-6 (IL-6) is a multifunctional cytokine with well-defined pro- and anti-inflammatory properties. Although only small amounts in the picogram range can be detected in healthy humans, IL-6 expression is highly and transiently up-regulated in nearly all pathophysiological states. IL-6 induces intracellular signaling pathways after binding to its membrane-bound receptor (IL-6R), which is only expressed on hepatocytes and certain subpopulations of leukocytes (classic signaling). Transduction of the signal is mediated by the membrane-bound β-receptor glycoprotein 130 (gp130). In a second pathway, named trans-signaling, IL-6 binds to soluble forms of the IL-6R (sIL-6R), and this agonistic IL-6/sIL-6R complexes can in principle activate all cells due to the uniform expression of gp130. Importantly, several soluble forms of gp130 (sgp130) are found in the human blood, which are considered to be the natural inhibitors of IL-6 trans-signaling. Most pro-inflammatory roles of IL-6 have been attributed to the trans-signaling pathway, whereas anti-inflammatory and regenerative signaling, including the anti-bacterial acute phase response of the liver, is mediated by IL-6 classic signaling. In this simplistic view, only a minority of cell types expresses the IL-6R and is therefore responsive for IL-6 classic signaling, whereas gp130 is ubiquitously expressed throughout the human body. However, several reports point towards a much more complex situation. A plethora of factors, including proteases, cytokines, chemical drugs, and intracellular signaling pathways, are able to modulate the cellular expression of the membrane-bound and soluble forms of IL-6R and gp130. In this review, we summarize current knowledge of regulatory mechanisms that control and regulate the dynamic expression of IL-6 and its two receptors.

Alternate virtual populations elucidate the type I interferon signature predictive of the response to rituximab in rheumatoid arthritis

Background

Mechanistic biosimulation can be used in drug development to form testable hypotheses, develop predictions of efficacy before clinical trial results are available, and elucidate clinical response to therapy. However, there is a lack of tools to simultaneously (1) calibrate the prevalence of mechanistically distinct, large sets of virtual patients so their simulated responses statistically match phenotypic variability reported in published clinical trial outcomes, and (2) explore alternate hypotheses of those prevalence weightings to reflect underlying uncertainty in population biology. Here, we report the development of an algorithm, MAPEL (Mechanistic Axes Population Ensemble Linkage), which utilizes a mechanistically-based weighting method to match clinical trial statistics. MAPEL is the first algorithm for developing weighted virtual populations based on biosimulation results that enables the rapid development of an ensemble of alternate virtual population hypotheses, each validated by a composite goodness-of-fit criterion.

Results

Virtual patient cohort mechanistic biosimulation results were successfully calibrated with an acceptable composite goodness-of-fit to clinical populations across multiple therapeutic interventions. The resulting virtual populations were employed to investigate the mechanistic underpinnings of variations in the response to rituximab. A comparison between virtual populations with a strong or weak American College of Rheumatology (ACR) score in response to rituximab suggested that interferon β (IFNβ) was an important mechanistic contributor to the disease state, a signature that has previously been identified though the underlying mechanisms remain unclear. Sensitivity analysis elucidated key anti-inflammatory properties of IFNβ that modulated the pathophysiologic state, consistent with the observed prognostic correlation of baseline type I interferon measurements with clinical response. Specifically, the effects of IFNβ on proliferation of fibroblast-like synoviocytes and interleukin-10 synthesis in macrophages each partially counteract reductions in synovial inflammation imparted by rituximab. A multianalyte biomarker panel predictive for virtual population therapeutic responses suggested population dependencies on B cell-dependent mediators as well as additional markers implicating fibroblast-like synoviocytes.

Conclusions

The results illustrate how the MAPEL algorithm can leverage knowledge of cellular and molecular function through biosimulation to propose clear mechanistic hypotheses for differences in clinical populations. Furthermore, MAPEL facilitates the development of multianalyte biomarkers prognostic of patient responses in silico.

Suppression of the growth of human colorectal cancer cells by therapeutic stem cells expressing cytosine deaminase and interferon-β via their tumor-tropic effect in cellular and xenograft mouse models

Genetically engineered stem cells (GESTECs) exhibit a potent therapeutic efficacy via their strong tumor tropism toward cancer cells. In this study, we introduced the human parental neural stem cells, HB1.F3, with the human interferon beta (IFN-β) gene which is a typical cytokine gene that has an antitumor effect and the cytosine deaminase (CD) gene from Escherichia coli (E. coli) that could convert the non-toxic prodrug, 5-fluorocytosine (5-FC), to a toxic metabolite, 5-fluorouracil (5-FU). Two types of stem cells expressing the CD gene (HB1.F3.CD cells) and both the CD and human IFN-β genes (HB1.F3.CD.IFN-β) were generated. The present study was performed to examine the migratory and therapeutic effects of these GESTECs against the colorectal cancer cell line, HT-29. When co-cultured with colorectal cancer cells in the presence of 5-FC, HB1.F3.CD and HB1.F3.CD.IFN-β cells exhibited the cytotoxicity on HT-29 cells via the bystander effect. In particular, HB1.F3.CD.IFN-β cells showed the synergistic cytotoxic activity of 5-FU and IFN-β. We also confirmed the migration ability of HB1.F3.CD and HB1.F3.CD.IFN-β cells toward HT-29 cells by a modified migration assay in vitro, where chemoattractant factors secreted by HT-29 cells attracted the GESTECs. In a xenograft mouse model, the volume of tumor mass was decreased up to 56% in HB1.F3.CD injected mice while the tumor mass was greatly inhibited about 76% in HB1.F3.CD.IFN-β injected mice. The therapeutic treatment by these GESTECs is a novel strategy where the combination of the migration capacity of stem cells as a vector for therapeutic genes towards colorectal cancer and a synergistic antitumor effect of CD and IFN-β genes can selectively target this type of cancer.

Effect of Platelet-activating Factor on in vitro and in vivo Interleukin-6 Production

The aim of the present study was to investigate the possible effect of platelet-activating factor (PAF), by comparison with interleukin-1beta and polyriboinositic/polyribocytidylic (poly I-C) acid, on IL-6 production by L 929 mouse fibroblasts. At concentrations above 1 muM PAF, the production of IL-6 by mouse fibroblasts was enhanced in a dose dependent fashion. At 5 muM PAF, the peak increase (60.1 +/- 19.4 U/ml) was similar to that induced by 50 mug/ml poly I-C (60.0 +/- 35.0 U/ml) and higher than the one evoked by 100 U/ml IL-1beta (3.8 +/- 1.8 U/ml). The increase of 11-6 activity induced by 5 muM PAF was maximal after a 22 h incubation period with L 929 cells. Lyso-PAF (5 muM) also increased IL-6 activity from fibroblasts to a similar extent compared with 5 muM PAF. In addition, the IL-6 activity induced by 5 muM PAF was still observed when the specific PAF antagonist, BN 52021 (10 muM), was added to the incubation medium of L 929 cells. The result suggests that the production of IL-6 by L 929 cells evoked by PAF in vitro is not receptor mediated. The in vivo effect of PAF on IL-6 production was also investigated in the rat. Two hours after intravenous injection of PAF (2 to 4 mug/kg), a dramatic increase of IL-6 activity in rat serum was observed, this effect being dose dependent. The increase of IL-6 induced by 3 mug/kg PAF was not observed when the animals were treated with the PAF antagonist, BN 52021 (1 to 60 mg/kg0. These results demonstrate that PAF modulates IL-6 production and that the in vivo effect is receptor mediated.

Cell-cell interaction of macrophages and vascular smooth muscle cells in the synthesis of leukotriene b(4)

Biosynthesis of LTB(4) during cell-cell interaction between vascular smooth muscle cells (SMC) and alveolar macrophages (AM) has been investigated by use of both high-pressure Hquid chromatography (HPLC) and radtoimmunoassay (RIA). Both interleukin-beta (IL-beta) and tumour necrosis factor-alpha (TNFalpha) induced a time- and dose-dependent synthesis of 15-, and 5-hydroxyeicosatetraenoic acids (HETEs) from cultured SMC. However, neither TNFalpha nor IL-1beta induced a significant LTB(4) production in SMC alone or AM alone after 24 h of incubation. Addition of IL-1beta and TNFalpha simultaneously to SMC resulted in a dose-dependent synergistic increase of HETEs. Macrophages dose-dependently transformed extremely low concentrations of exogenous LTA(4) into LTB(4). Incubation of vascular SMC with various numbers of AM in the presence of IL-1beta (5 units/ml) and TNFalpha (10 units/ml) induced a great increase of LTB(4) synthesis in comparison with the detectable levels of LTB(4) produced by macrophages alone. Pretreatment of SMC with NDGA, cycloheximide, and actinomycin not only inhibited IL-1 and TNT induced HETEs synthesis but also abolished LTB(4) production when co-incubated with macrophages. These results suggest that LTB(4) in a mixture of SMC and macrophages could originate from a transcellular metabolism, i.e. macrophages transforming SMC-derived LTA(4) into LTB(4).

Intrinsic growth deficiencies of mesenchymal stromal cells in myelodysplastic syndromes

Myelodysplastic syndromes (MDSs) are clonal disorders of hematopoietic stem cells (HSCs) characterized by ineffective hematopoiesis. MDSs are responsible for 1 or several peripheral cytopenias. The evidence accumulated in recent years demonstrates that in addition to HSC defects, a particular role is also played by stromal microenvironment dysfunctions, which mediate the direct contact with hematopoietic precursor cells (HPCs). These interactions help regulate different adhesion-related processes, such as progenitor cell proliferation, apoptosis, clonogenic growth, and maintenance in in vitro cultures. As previously reported, these interactions are responsible for altering the microenvironment in MDS. Herein, we present a novel selection protocol for obtaining a standards-compliant mesenchymal stromal cell (MSC) preparation. This method allowed us to comparatively analyze 2 subpopulations of bone marrow MSCs (BM-MSCs) in terms of their adhesion profiles and growth abilities: BM-MSCs selected from MDS settings and their normal counterparts. Functional assays revealed that the MSCs from MDS are intrinsically pathological, thus showing a continuous decline of proliferation and a reduced clonogenic capacity during 14 days of culture and in the absence of signals from hematopoietic cells. The MSC growth defects were significantly correlated with decreases in CD44 adhesion molecules and CD49e (α5-integrin).

Interleukin-1 activates synthesis of interleukin-6 by interfering with a KH-type splicing regulatory protein (KSRP)-dependent translational silencing mechanism

Post-transcriptional mechanisms play an important role in the control of inflammatory gene expression. The heterogeneous nuclear ribonucleoprotein K homology (KH)-type splicing regulatory protein (KSRP) triggers rapid degradation of mRNAs for various cytokines, chemokines, and other inflammation-related proteins by interacting with AU-rich elements (AREs) in the 3'-untranslated mRNA regions. In addition to destabilizing mRNAs, AU-rich elements can restrict their translation. Evidence that KSRP also participates in translational silencing was obtained in a screen comparing the polysome profiles of cells with siRNA-mediated depletion of KSRP with that of control cells. Among the group of mRNAs showing increased polysome association upon KSRP depletion are those of interleukin (IL)-6 and IL-1α as well as other ARE-containing transcripts. Redistribution of IL-6 mRNA to polysomes was associated with increased IL-6 protein secretion by the KSRP-depleted cells. Silencing of IL-6 and IL-1α mRNAs depended on their 3'-untranslated regions. The sequence essential for translational control of IL-6 mRNA and its interaction with KSRP was located to an ARE. KSRP-dependent silencing was reversed by IL-1, a strong inducer of IL-6 mRNA and protein expression. The results identify KSRP as a protein involved in ARE-mediated translational silencing. They suggest that KSRP restricts inflammatory gene expression not only by enhancing degradation of mRNAs but also by inhibiting translation, both functions that are counteracted by the proinflammatory cytokine IL-1.

Honey promotes angiogeneic activity in the rat aortic ring assay

OBJECTIVE

To investigate possible effects of honey on angiogenesis, using in vitro analogues of angiogenesis and an endothelial proliferation assay.

METHOD

Using an in vitro rat aortic ring assay we compared pseudotubule formation by medicinal honey (Activon), supermarket honey (Rowse) and a honey-based ointment (Mesitran), with that of artificial honey (70% w/w sugar glucose/fructose). Pseudotubules were analysed using TCS Cellworks AngioSys software. The Angiokit sytem was used to validate the results. Using the MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium. Bromide] assay, toxicity was also assessed on human umbilical vein endothelial cells (HUVEC) directly adherent to plastic.

RESULTS

All honey preparations stimulated pseudotubule formation, maximal at around 0.2% honey. Medicinal honeys were more active than Rowse. The effect was not attributable to the sugar content. Among the honeys tested, the Manuka-based Activon preparation reduced residual viable biomass compared with a sugar control at > 0.32% v/v concentration. Rowse had a similar effect only at 2.5%, the highest dose tested.

CONCLUSION

The influence of honey constituents on angiogenesis in a wound dressing context is likely to be positive, but would depend on the effective dilution of the honey and the penetration of the active constituents against an osmotic gradient. The extent to which this occurs has yet to be established.

CONFLICT OF INTEREST

This work was conceived, designed and executed by the authors. Medical honey preparations were supplied unconditionally but free of charge by the distributors.

HERPES SIMPLEX VIRUS INFECTION AND APOPTOSIS

Consequences of human herpes simplex virus (HSV) infection include the induction of apoptosis and the concomitant synthesis of proteins which act to block this process from killing the infected cell. Recent data has clarified our current understanding of the mechanisms of induction and prevention of apoptosis by HSV. These findings emphasize the fact that modulation of apoptosis by HSV during infection is a multicomponent phenomenon. We review recent evidence showing how this important human pathogen modulates the fundamental cell death process.

Biologic and clinical significance of cytokine production in B-cell malignancies

Cytokines are a group of polypeptide hormones endowed with pleiotropic biological properties. Normal B lymphocytes produce a number of these factors that subserve important regulatory functions in the combined processes of proliferation and differentiation. Also neoplastic B cells can release cytokines and, simultaneously, respond to the same factors in an autocrine circuit that supports their malignant growth. In addition, tumor cells can make use of the factors released by normal cells, either spontaneously or under the influence of inductive signals from the neoplastic cells. Inappropriate or excessive release of cytokines may have an important role in the pathophysiology of some clinical features. Thus, neutralization of cytokine biologic activity in vivo could be a therapeutic strategy for treatment of human B-cell neoplasias.

Genetic polymorphisms in immunoresponse genes TNFA, IL6, IL10, and TLR4 are associated with recurrent acute otitis media

OBJECTIVE

Cytokines and other inflammatory mediators are involved in the pathogenesis of otitis media. We hypothesized that polymorphisms in inflammatory response genes contribute to the increased susceptibility to acute otitis media in otitis-prone children.

PATIENTS AND METHODS

DNA samples from 348 children with > or = 2 acute otitis media episodes, who were participating in a randomized, controlled vaccination trial, and 463 healthy adult controls were included. Polymorphisms in TNFA, IL1B, IL4, IL6, IL10, IL8, NOS2A, C1INH, PARP, TLR2, and TLR4 were genotyped. Genotype distributions in children with recurrent acute otitis media were compared with those in controls. Within the patient group, the number of acute otitis media episodes before vaccination and the clinical and immunologic response to pneumococcal conjugate vaccinations were analyzed.

RESULTS

The IL6-174 G/G genotype was overrepresented in children with acute otitis media when compared with controls. In the patient group, TNFA promoter genotypes -238 G/G and -376 G/G and the TLR4 299 A/A genotype were associated with an otitis-prone condition. Furthermore, lower specific anticapsular antibody production after complete vaccination was observed in patients with the TNFA-238 G/G genotype or TNFA-863 A allele carriage. Finally, the IL10-1082 A/A genotype contributed to protection from the recurrence of acute otitis media after pneumococcal vaccination.

CONCLUSIONS

Variation in innate immunoresponse genes such as TNFA-863A, TNFA-376G, TNFA-238G, IL10-1082 A, and IL6-174G alleles in the promoter sequences may result in altered cytokine production that leads to altered inflammatory responses and, hence, contributes to an otitis-prone condition.

Structure-function relationship of tumour necrosis factor and its mechanism of action

We have cloned the cDNAs of both human and mouse TNF and expressed them to high efficiency in Escherichia coli. Many transformed cell lines are sensitive to the cytotoxic action of TNF, especially in the presence of gamma-interferon, whereas normal cells either are unaffected or respond mitogenically. A number of human-mouse chimeric TNF genes have been constructed and expressed. All show biological activity but none of the chimeric proteins is neutralized by monoclonal antibodies to TNF. TNF has potent antitumour activity in nude mice carrying human xenografts or in mice bearing syngeneic tumours. In some systems direct effects can be demonstrated (in combination with species-specific gamma-interferon) but in others TNF acts indirectly. Combination of TNF with cytostatic drugs can also be effective in curing in vivo. The major limitation of the use of TNF is its toxicity. On many cell types TNF has an action similar to interleukin 1 (IL-1). At least some of the secondary, intracellular events may be identical for the two effectors. A possible mechanism of action of TNF is the release and metabolism of polyunsaturated fatty acids, which would explain the synthesis of prostaglandins and leukotrienes by many cell types after TNF treatment. The activation of the phospholipase can be blocked by corticoids. Some protease inhibitors protect cells from TNF-induced cytotoxicity but the target of these inhibitors has not been identified. Several genes are switched on by TNF (and by IL-1), including the gene for the 26 kDa protein recently identified as B cell stimulation factor 2. Events preceding death in rats include hypothermia, hypotension, acidosis and hypoglycaemia. All these effects can be largely eliminated by indomethacin pretreatment, with a resulting improvement in survival. As indomethacin does not inhibit the cytotoxic action of TNF on malignant cells it may form the basis for improved treatment protocols.

Interferons: cytokines in autoimmunity

The presence of circulating interferons in the blood of patients with autoimmune diseases and the acquired immune deficiency syndrome (AIDS) raises the question of their possible pathogenetic or defence functions. Interferons control levels of HLA class I and II antigens on cells and can activate or inhibit immune killer cell activities. Tumour necrosis factors (TNF) and interleukin 1 induce a new autocrine species of interferon known as IFN-beta-2 whose gene has been cloned, sequenced and expressed. This IFN mediates the increase in HLA expression caused by TNF as well as the antiviral activity of this cytotoxin.

Effects of tumour necrosis factor and related cytokines on vascular endothelial cells

Tumour necrosis factor (TNF) and related cytokines have been found to alter the phenotype of vascular endothelial cells so as to promote coagulation, inflammation and immunity. We have used recombinant human TNF, lymphotoxin (LT), interleukin 1 alpha (IL-1 alpha) and interleukin 1 beta (IL-1 beta) to study and compare the effects of these molecules on cultured human endothelial cells (HEC). All four mediators cause HEC monolayers to reorganize from an epithelioid to a fibroblastoid morphology. Reorganization is slow (days), reversible upon cytokine withdrawal and enhanced by co-addition of immune interferon. Coincident with morphological change, TNF and LT (but not IL-1 alpha or IL-1 beta) cause a marked increase in HLA-A, B mRNA and antigen expression. TNF and LT also induce a slow increase in the mRNA levels and cell-surface expression of IL-1 species. All four cytokines have been reported to enhance HEC adhesiveness for lymphocytes and inflammatory leucocytes; these changes temporally coincide with a rapid (hours) and sustained increase in expression of intercellular adhesion molecule 1 (ICAM-1), and with a rapid but transient de novo expression of an endothelial-leucocyte adhesion molecule (detected by antibody H4/18), respectively. TNF and LT induce reciprocal tachyphylaxis for the reinduction of H4/18 binding but do not inhibit induction by IL-1 alpha and IL-1 beta; similarly, IL-1 alpha and IL-1 beta induce reciprocal tachyphylaxis but do not inhibit TNF or LT. We have used the binding of H4/18 to explore the mechanism of action of TNF. Tumour-promoting phorbol esters, but not agents which increase cytoplasmic calcium concentrations, were found to induce binding, suggesting a possible involvement of the protein kinase C pathway in the response of HEC to TNF. Cells pretreated for 24 hours with phorbol esters cannot be reinduced to express H4/18 binding by phorbol esters yet retain full responsiveness to TNF. Thus TNF also appears to act on HEC through a pathway independent of protein kinase C activation. Collectively, these effects of TNF and related cytokines may be understood as examples of endothelial cell activation.

Herpes simplex virus blocks Fas-mediated apoptosis independent of viral activation of NF-kappaB in human epithelial HEp-2 cells

The goal of our study was to characterize the apoptotic response of herpes simplex virus (HSV)-infected, human epithelial HEp-2 cells to extrinsic treatments through the Fas receptor. Initially, we defined the Fas response of these cells. We found the following: (1) Treatment of HEp-2 cells with anti-Fas antibody or Fas ligand (FasL) alone did not induce apoptosis. (2) In addition, these inducers did not activate NF-kappaB in these cells. (3) The addition of cycloheximide (CHX) during these treatments caused a dramatic increase in programmed cell death. (4) HEp-2 cells infected with HSV for 6 h prior to anti-Fas plus CHX treatment were nonapoptotic, and (5) these cells possessed nuclear NFkappaB. (6) HSV blocked anti-Fas or FasL plus CHX-induced apoptosis in HEp-2 cells that stably expressed a dominant-negative form of IkappaBalpha. These results indicate that HSV infection can block the process of Fas-mediated apoptosis through a mechanism that is independent of viral activation of NFkappaB. Our findings help define the molecular mechanisms involved in HSV evasion of the cytokine-driven, innate immune response in human epithelial cells.

Does the human leukaemia differentiation factor fragment HLDF6 improve memory via brain DNA and protein synthesis?

The novel human differentiating factor peptide fragment HLDF6 (Thr-Gly-Glu-Asn-His-Arg) was synthesized and purified. HLDF6 (0.1mg/kg i.p. but not 1mg/kg i.p.) improved not only long-term (24h) memory in adult rats in the water maze behavioural paradigm but also performance in the delayed matching-to-position (DMTP) task (0.3 and 1.0 but not 0.1mg/kg i.p). Hence, HLDF6 not only enhanced allocentric spatial learning and reference memory (water maze) but also improved temporal, spatial and working memory processes in the DMTP behavioural paradigm. Immunoreactivity blotting analysis of HLDF (the protein precursor of HLDF6) was performed and the following rank order of visual intensities from brain structures was noted: hippocampus cerebral cortex cerebellum hypothalamus striatum. Subsequently, we found that the highest absolute levels of HLDF were expressed in the hippocampus and cerebral cortex as detected by ELISA. We also demonstrated that HLDF6 enhanced [(3)H]-thymidine and [(14)C]-leucine incorporation into whole brain and hippocampal homogenates (maxima occurring within the range 10 (-12)-10 (-6) M) suggesting that this hexapeptide promoted de novo DNA and protein biosynthesis. We discuss this data in terms of their implications for links with other integrative metabolic pathways involving immediate early gene activation which may underpin a potential application for HLDF6 in limiting memory impairments associated with neurodegenerative diseases.

Immunohistochemical assessment of mucosal cytokine profile in acetic acid experimental colitis

Experimental colitis induced by acetic acid has been used extensively as a model for intestinal inflammatory disease. Colonic tissue lesions of intestinal inflammatory disease patients seem to be related to the increased local production of pro-inflammatory cytokines (IL-1, IL-6, TNF-alpha, and IFN-gamma).

PURPOSE

To assess the cytokine expression pattern identified through immunohistochemistry in colonic mucosa after experimental colitis induced by acetic acid and establish the relationship between this pattern and the presence of macroscopic lesions.

MATERIALS AND METHODS

Adult male Wistar rats (n = 39) were divided at random into 4 groups: NC45 and NC24 (control without colitis; sacrificed at 45 minutes and 24 hours, respectively); and WC45 and WC24 (with experimental colitis induced by acetic acid; sacrificed at 45 minutes and 24 hours, respectively). Macroscopic and microscopic alterations in colonic tissue were evaluated, and cytokine expression was assessed through immunohistochemistry.

RESULTS

After 24 hours, IL-1 expression was greater in the groups with colitis when compared to the groups without colitis. IL-4 expression was higher in the WC45 group. There was an increase in both INF-gamma and IL-6 related to the presence of necrosis of the colonic mucosa in the groups with colitis for both periods evaluated.

CONCLUSION

The immunohistochemical technique was efficient for the analysis of various cytokine expressions in the colonic tissue. There was an increase in the IL-1 pro-inflammatory cytokines as well as in IL-6 and IFN-gamma associated with the presence of colonic necrosis. Experimental colitis induced by acetic acid is a useful model for the development of studies assessing the role of cytokines in the inflammation of mucosa as well as anti-cytokine therapies.

Interleukin-6, interleukin-8, interleukin-11, and interferon-gamma levels in nasopharyngeal aspirates from wheezing children with respiratory syncytial virus or influenza A virus infection

The differences between respiratory syncytial virus (RSV) and influenza A virus (IFAV) in the pathogenesis of wheezing in young children have not been clearly defined. The aim of this study was to assess the contributions of RSV vs IFAV in the pathogenesis of upper airway inflammation in wheezy young children. We compared interleukin (IL)-6, IL-8, IL-11, and interferon-gamma (IFN-gamma) levels in nasopharyngeal aspirates (NPA) from non-asthmatic children with respiratory virus infections (RSV in 17 children and IFAV in 13 children), asthmatic children with viral infections (RSV in nine children, IFAV in 10 children), and 22 unaffected healthy children (controls). Levels of IL-11 in NPA from asthmatic children were significantly higher than those from non-asthmatic children with RSV infection, and RSV infection enhanced the IL-11 production in NPA significantly compared to IFAV infection. Nasopharyngeal epithelium from children with RSV infection secreted more IL-6 than that of children with IFAV infection. There was little difference in the IL-8 and IFN-gamma levels between asthmatic and non-asthmatic children with RSV or IFAV infection. In conclusion, asthma enhanced IL-11 production in RSV infection rather than IFAV infection in early childhood. There was a trend towards greater IL-6 production in RSV infection compared with IFAV infection.

C-reactive protein as a biomarker of emergent osteoarthritis

OBJECTIVE

We evaluated C-reactive protein (C-RP), a quantitative marker of the acute phase response, as a potential biomarker of prevalent and incident osteoarthritis of the knee (OAK).

METHODS

Serum C-reactive protein concentrations were characterized with ultrasensitive rate nephelometry in a population-based sample of 1025 women (318 African-American and 707 Caucasian) who are enrollees in a study of musculoskeletal conditions at the mid-life. Assignment of OAK was based on Kellgren-Lawrence (K-L) scores of 2 or more on radiographs. Prevalent OAK was based on the baseline (1996) score while the classification of incident OAK was based on a score of 2 or greater at the follow-up examination 2.5 years later amongst those with a baseline K-L scores of 0 or 1.

RESULTS

At baseline, the prevalence of radiographic OAK was 12% in participants who were aged 27-53 years and 18% in the subgroup of women aged 40-53 years. The mean C-RP value was 2.31 mg/L, with values ranging from below detection (0.3 mg/L) to 47.4 mg/L. Higher C-RP concentrations were associated with both prevalent and incident OAK (P < 0.0001, and P < 0.0001, respectively). For each K-L score increase from 0 to 3, there was a significantly higher mean C-RP value. Compared to women without incident OAK, women who developed OAK in the 2.5-year follow-up had significantly higher baseline C-RP concentrations. Women with bilateral OAK had higher C-RP concentrations than women with unilateral OAK (6.65 mg/L +/- 0.56 vs 3.63 mg/L +/- 0.42, P < 0.007). BMI was highly correlated with C-RP (r = 0.58) and obesity was an effect modifier with respect to OAK and C-RP concentrations. When stratified according presence or absence of OAK and obesity (BMI > 30 kg/m2), mean C-RP values were: obesity and OAK, 6.3 +/- 0.4 mg/L; obesity but not OAK, 4.3 mg/L +/- 0.2; no obesity but OAK, 1.7 mg/L +/- 0.8; and neither obesity nor OAK, 1.3 mg/L +/- 0.2 mg/L. These stratum means were significantly different from each other, indicating a higher C-RP with OAK after accounting for obesity.

CONCLUSION

C-RP, as a measure of an acute phase response and inflammation, is highly associated with OAK; however, its high correlation with obesity limits its utility as an exclusive marker for OAK.

Immunomodulatory effects of interferon-beta-1b in patients with multiple sclerosis

The mechanisms by which IFN beta-1b acts in the treatment of patients with multiple sclerosis (MS) are not completely known. Immunomodulatory effects of IFN beta-1b were investigated in patients with relapsing-remitting (RR) MS in vivo and in vitro. Compared to baseline and controls, defined as patients with RR-MS without immunomodulatory therapy, the expression of TGF beta-1-mRNA by peripheral blood mononuclear cells (PBMC) was persistently increased at week 6, month 3 and month 6 (p < or = 0.05), that of the TGF beta-1 receptor type II from day 5 up to month 6 (p < 0.01). The expression of TNF alpha-mRNA decreased from day 1 to month 3 compared to day 0 and the controls (p < 0.01). The in vitro investigations performed on isolated peripheral blood lymphocytes demonstrated that these effects were dose-dependent. The mRNA and protein expression of TNF alpha-R-I (55 kD-receptor) was only temporarily elevated at the beginning of the therapy in vivo. The expression of TNF alpha-R-I-mRNA increased dose-dependently after stimulation with IFN beta-1b for 24 h in vitro. Serum levels of soluble vascular cell adhesion molecule (sVCAM) were increased during the whole time of in vivo treatment (p < 0.01). The CD8CD38 lymphocyte subpopulation was continuously elevated from day 5 up to month 6 (p < 0.01) in the MS patients treated with IFN beta-1b in vivo. No persistent, significant changes were demonstrable concerning the percentage of total CD4, CD8, CD19 nor in CD4 subpopulations (CD4CD29, CD4CD45RA). The present data suggest that IFN beta-1b induces the mRNA expression of TGF beta-1 and TGF beta-R-II by PBMC, decreases that of TNF alpha and increases levels of sVCAM-1 and of circulating activated CD8 cells (CD8CD38) in blood. These might be other mechanisms by which IFN beta-1b mediates its positive effects in the treatment of MS patients.

Interferon Alpha, GM-CSF-Activated T Cells, and IL-6 in Renal Cell Carcinoma

Treatment of renal cell carcinoma (RCC) has historically involved surgical removal of the primary tumor when localized, but when presented with metastatic disease the options have been limited. Approximately 30% of patients present with metastatic disease implicating a generally poor prognosis. The most significant advances have occurred in the area of immunotherapy as treatment for metastatic disease. This is because RCC is generally resistant to chemotherapy and radiation. One of the major successes of immunotherapy has been with interleukin-2 (IL-2). Initial IL-2 therapy proved difficult due to the significant administrative and side effect problems that occurred. This led to numerous variations in dose scheduling and delivery to identify an optimal beneficial way of administering IL-2. In addition, investigation also led to other immunotherapy agents such as interferon and cellular therapy.

Suppression of interferon-induced antiviral activity in cells expressing hepatitis C virus proteins

To elucidate the mechanism of the persistent nature of hepatitis C virus (HCV) infection, we examined whether the expression of HCV proteins affect the antiviral activity of interferon (IFN). Antiviral activity of IFN in HepG2 cells expressing all HCV (type 1b) proteins was much lower than vector control (VC) HepG2 cells when encephalomyocarditis virus (EMCV) was used as a challenge virus. Lesser sensitivity to IFN was also observed in cells expressing NS3, NS4, and NS5 and in cells expressing only NS5A. In contrast, HepG2 cells expressing core, E1, E2, NS2, and NS3 proteins were equally sensitive to IFN as VC cells. We then tested the antiviral activity by IFN in two human amnion-derived FL cell lines expressing NS5A from two different clones, one with an intact sequence of IFN sensitivity-determining region (ISDR) and the other with a mutated ISDR sequence. They were almost equally insensitive to IFN treatment when EMCV was challenged. HCV thus has functional protein(s), possibly NS5A, to suppress IFN-induced antiviral activity and plays an important role in virus-cell interaction and regulation of viral replication.

Salmeterol enhances the inhibitory activity of dexamethasone on allergen-induced blood mononuclear cell activation

The possibility that salmeterol could interfere with the inhibitory effect of glucocorticosteroids on allergen-induced activation of leukocytes was assessed in cultures of human blood mononuclear cells (BMCs). BMCs, recovered from 27 patients (21 +/- 4 years of age) sensitized to Dermatophagoides pteronyssinus (Der p), were incubated with a purified Der p extract (10 micrograms/ml) for 7 days in the presence of salmeterol (10(-8) and 10(-7) M) and/or dexamethasone (10(-10) and 10(-9) M). BMC proliferation and cytokine release were respectively tested by [3H]thymidine incorporation and EASIA. Stimulation with Der p extract induced a significant BMC proliferation (Der p 18.7 +/- 1.9 cpm x 10(3), control 1.8 +/- 0.3 cpm x 10(3), p < 0.01) which was significantly inhibited both by salmeterol and dexamethasone (p < 0.05, each comparison). The inhibition of BMC proliferation induced by dexamethasone (10(-9) M) was significantly enhanced by salmeterol 10(-7) M (p < 0.05). Evaluation of cytokine levels in BMC supernatants showed that Der p extract significantly increased the release of granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1 beta and IL-2 (p < 0.001, each comparison). Salmeterol (10(-7) M) or dexamethasone (10(-9) M) induced a similar, statistically significant, downregulation of GM-CSF release (p < 0.05, each comparison) and induced a slight, not significant, decrease in the production of IFN-gamma, TNF-alpha, IL-1 beta and IL-2 (p > 0.05 each comparison). Interestingly, salmeterol (10(-7) M) significantly enhanced the inhibitory activity of dexamethasone (10(-9) M) on the release of GM-CSF, TNF-alpha, IL-1 beta and IL-2 (p < 0.05, each comparison) but not of IFN-gamma (p > 0.05). Thus beta 2-adrenoceptors may enhance the inhibitory activity of low doses of corticosteroids on allergen-induced BMC activation.