Limited dynamic range of immune response gene expression observed in healthy blood donors using RT-PCR

Using transcriptomics to predict and visualize disease status in bighorn sheep (Ovis canadensis)

Increasing risk of pathogen spillover coupled with overall declines in wildlife population abundance in the Anthropocene make infectious disease a relevant concern for species conservation worldwide. While emerging molecular tools could improve our diagnostic capabilities and give insight into mechanisms underlying wildlife disease risk, they have rarely been applied in practice. Here, employing a previously reported gene transcription panel of common immune markers to track physiological changes, we present a detailed analysis over the course of both acute and chronic infection in one wildlife species where disease plays a critical role in conservation, bighorn sheep (Ovis canadensis). Differential gene transcription patterns distinguished between infection statuses over the course of acute infection and differential correlation (DC) analyses identified clear changes in gene co-transcription patterns over the early stages of infection, with transcription of four genes-TGFb, AHR, IL1b and MX1-continuing to increase even as transcription of other immune-associated genes waned. In a separate analysis, we considered the capacity of the same gene transcription panel to aid in differentiating between chronically infected animals and animals in other disease states outside of acute disease events (an immediate priority for wildlife management in this system). We found that this transcription panel was capable of accurately identifying chronically infected animals in the test dataset, though additional data will be required to determine how far this ability extends. Taken together, our results showcase the successful proof of concept and breadth of potential utilities that gene transcription might provide to wildlife disease management, from direct insight into mechanisms associated with differential disease response to improved diagnostic capacity in the field.

Baseline Gene Expression Levels in Falkland-Malvinas Island Penguins: Towards a New Monitoring Paradigm

Health diagnostics of wildlife have historically relied on the evaluation of select serum biomarkers and the identification of a contaminant or pathogen burden within specific tissues as an indicator of a level of insult. However, these approaches fail to measure the physiological reaction of the individual to stressors, thus limiting the scope of interpretation. Gene-based health diagnostics provide an opportunity for an alternate, whole-system, or holistic assessment of health, not only in individuals or populations but potentially in ecosystems. Seabirds are among the most threatened marine taxonomic groups in the world, with ~25% of this species currently listed as threatened or considered of special concern; among seabirds, the penguins (Family Spheniscidae) are the most threatened seabird Family. We used gene expression to develop baseline physiological indices for wild penguins in the Falkland-Malvinas Islands, and captive zoo penguins. We identified the almost complete statistical separation of penguin groups (gentoo Detroit Zoo, gentoo Falkland-Malvinas Islands, rockhopper Detroit Zoo, and rockhopper Falkland-Malvinas Islands) based on gene expression profiles. Implementation of long-term longitudinal studies would allow for the assessment of temporal increases or decreases of select transcripts and would facilitate interpretation of the drivers of change.

Gene Expression Profiles in Two Razor Clam Populations: Discerning Drivers of Population Status

With rapidly changing marine ecosystems, shifts in abundance and distribution are being documented for a variety of intertidal species. We examined two adjacent populations of Pacific razor clams (Siliqua patula) in lower Cook Inlet, Alaska. One population (east) supported a sport and personal use fishery, but this has been closed since 2015 due to declines in abundance, and the second population (west) continues to support commercial and sport fisheries. We used gene expression to investigate potential causes of the east side decline, comparing razor clam physiological responses between east and west Cook Inlet. The target gene profile used was developed for razor clam populations in Alaska based on physiological responses to environmental stressors. In this study, we identified no differences of gene expression between east and west populations, leading to two potential conclusions: (1) differences in factors capable of influencing physiology exist between the east and west and are sufficient to influence razor clam populations but are not detected by the genes in our panel, or (2) physiological processes do not account for the differences in abundance, and other factors such as predation or changes in habitat may be impacting the east Cook Inlet population.

Monitoring nearshore ecosystem health using Pacific razor clams (Siliqua patula) as an indicator species

An emerging approach to ecosystem monitoring involves the use of physiological biomarker analyses in combination with gene transcription assays. For the first time, we employed these tools to evaluate the Pacific razor clam (Siliqua patula), which is important both economically and ecologically, as a bioindicator species in the northeast Pacific. Our objectives were to (1) develop biomarker and gene transcription assays with which to monitor the health of the Pacific razor clam, (2) acquire baseline biomarker and gene transcription reference ranges for razor clams, (3) assess the relationship between physiological and gene transcription assays and (4) determine if site-level differences were present. Pacific razor clams were collected in July 2015 and 2016 at three sites within each of two national parks in southcentral Alaska. In addition to determining reference ranges, we found differences in biomarker assay and gene transcription results between parks and sites which indicate variation in both large-scale and local environmental conditions. Our intent is to employ these methods to evaluate Pacific razor clams as a bioindicator of nearshore ecosystem health. Links between the results of the biomarker and gene transcription assays were observed that support the applicability of both assays in ecosystem monitoring. However, we recognize the need for controlled studies to examine the range of responses in physiology and gene transcripts to different stressors.

Physiological and gene transcription assays to assess responses of mussels to environmental changes

Coastal regions worldwide face increasing management concerns due to natural and anthropogenic forces that have the potential to significantly degrade nearshore marine resources. The goal of our study was to develop and test a monitoring strategy for nearshore marine ecosystems in remote areas that are not readily accessible for sampling. Mussel species have been used extensively to assess ecosystem vulnerability to multiple, interacting stressors. We sampled bay mussels (Mytilus trossulus) in 2015 and 2016 from six intertidal sites in Lake Clark and Katmai National Parks and Preserves, in south-central Alaska. Reference ranges for physiological assays and gene transcription were determined for use in future assessment efforts. Both techniques identified differences among sites, suggesting influences of both large-scale and local environmental factors and underscoring the value of this combined approach to ecosystem health monitoring.

Lipoprotein-associated phospholipase A2: The story continues

Inflammation is thought to play an important role in the pathogenesis of vascular diseases. Lipoprotein-associated phospholipase A2 (Lp-PLA2) mediates vascular inflammation through the regulation of lipid metabolism in blood, thus, it has been extensively investigated to identify its role in vascular inflammation-related diseases, mainly atherosclerosis. Although darapladib, the most advanced Lp-PLA2 inhibitor, failed to meet the primary endpoints of two large phase III trials in atherosclerosis patients cotreated with standard medical care, the research on Lp-PLA2 has not been terminated. Novel pathogenic, epidemiologic, genetic, and crystallographic studies regarding Lp-PLA2 have been reported recently, while novel inhibitors were identified through a fragment-based lead discovery strategy. More strikingly, recent clinical and preclinical studies revealed that Lp-PLA2 inhibition showed promising therapeutic effects in diabetic macular edema and Alzheimer's disease. In this review, we not only summarized the knowledge of Lp-PLA2 established in the past decades but also emphasized new findings in recent years. We hope this review could be valuable for helping researchers acquire a much deeper insight into the nature of Lp-PLA2, identify more potent and selective Lp-PLA2 inhibitors, and discover the potential indications of Lp-PLA2 inhibitors.

Using Gene Transcription to Assess Ecological and Anthropological Stressors in Brown Bears

Increasingly, population- and ecosystem-level health assessments are performed using sophisticated molecular tools. Advances in molecular technology enable the identification of synergistic effects of multiple stressors on the individual physiology of different species. Brown bears (Ursus arctos) are an apex predator; thus, they are ideal candidates for detecting potentially ecosystem-level systemic perturbations using molecular-based tools. We used gene transcription to analyze 130 brown bear samples from three National Parks and Preserves in Alaska. Although the populations we studied are apparently stable in abundance and exist within protected and intact environments, differences in transcript profiles were noted. The most prevalent differences were among locations. The transcript patterns among groups reflect the influence of environmental factors, such as nutritional status, disease, and xenobiotic exposure. However, these profiles also likely represent baselines for each unique environment by which future measures can be made to identify early indication of population-level changes due to, for example, increasing Arctic temperatures. Some of those environmental changes are predicted to be potentially positive for brown bears, but other effects such as the manifestation of disease or indirect effects of oceanic acidification may produce negative impacts.

DEVELOPMENT AND VALIDATION OF QUANTITATIVE PCR ASSAYS TO MEASURE CYTOKINE TRANSCRIPT LEVELS IN THE FLORIDA MANATEE ( TRICHECHUS MANATUS LATIROSTRIS)

Cytokines have important roles in the mammalian response to viral and bacterial infections, trauma, and wound healing. Because of early cytokine production after physiologic stresses, the regulation of messenger RNA (mRNA) transcripts can be used to assess immunologic responses before changes in protein production. To detect and assess early immune changes in endangered Florida manatees ( Trichechus manatus latirostris), we developed and validated a panel of quantitative PCR assays to measure mRNA transcription levels for the cytokines interferon (IFN)-γ; interleukin (IL)-2, -6, and -10; tumor necrosis factor-α; and the housekeeping genes glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and β-actin (reference genes). Assays were successfully validated using blood samples from free-ranging, apparently healthy manatees from the east and west coasts of central Florida, US. No cytokine or housekeeping gene transcription levels were significantly different among age classes or sexes. However, the transcription levels for GAPDH, IL-2, IL-6, and IFN-γ were significantly higher ( P<0.05) in manatees from the east coast of Florida than they were from those from the west coast. We found IL-10 and β-actin to be consistent between sites and identified β-actin as a good candidate for use as a reference gene in future studies. Our assays can aid in the investigation of manatee immune response to physical trauma and novel or ongoing environmental stressors.

Coupling gene-based and classic veterinary diagnostics improves interpretation of health and immune function in the Agassiz's desert tortoise (Gopherus agassizii)

The analysis of blood constituents is a widely used tool to aid in monitoring of animal health and disease. However, classic blood diagnostics (i.e. hematologic and plasma biochemical values) often do not provide sufficient information to determine the state of an animal's health. Field studies on wild tortoises and other reptiles have had limited success in drawing significant inferences between blood diagnostics and physiological and immunological condition. However, recent research using gene transcription profiling in the threatened Mojave desert tortoise (Gopherus agassizii) has proved useful in identifying immune or physiologic responses and overall health. To improve our understanding of health and immune function in tortoises, we evaluated both standard blood diagnostic (body condition, hematologic, plasma biochemistry values, trace elements, plasma proteins, vitamin A levels) and gene transcription profiles in 21 adult tortoises (11 clinically abnormal; 10 clinically normal) from Clark County, NV, USA. Necropsy and histology evaluations from clinically abnormal tortoises revealed multiple physiological complications, with moderate to severe rhinitis or pneumonia being the primary cause of morbidity in all but one of the examined animals. Clinically abnormal tortoises had increased transcription for four genes (SOD, MyD88, CL and Lep), increased lymphocyte production, biochemical enzymes and organics, trace elements of copper, and decreased numbers of leukocytes. We found significant positive correlations between increased transcription for SOD and increased trace elements for copper, as well as genes MyD88 and Lep with increased inflammation and microbial insults. Improved methods for health assessments are an important element of monitoring tortoise population recovery and can support the development of more robust diagnostic measures for ill animals, or individuals directly impacted by disturbance.

Plasma PAF-AH (PLA2G7): Biochemical Properties, Association with LDLs and HDLs, and Regulation of Expression

This chapter is focused on the plasma form of PAF-acetylhydrolase (PAF-AH), a lipoprotein-bound, calcium-independent phospholipase A2 activity also referred to as lipoprotein-associated phospholipase A2 and PLA2G7. PAF-AH catalyzes the removal of the acyl group at the sn-2 position of PAF and truncated phospholipids generated in settings of inflammation and oxidant stress. Here, I discuss current knowledge related to the structural features of this enzyme, including the molecular basis for association with lipoproteins and susceptibility to oxidative inactivation. The circulating form of PAF-AH is constitutively active and its expression is upregulated by mediators of inflammation at the transcriptional level. Several new mechanisms of regulation have been identified in recent years, including effects mediated by PPARs, VEGFR, and the state of cellular differentiation. Moreover, I discuss recent studies describing significant variations in the structure and regulation of PAF-AH from diverse species, which is likely to have important implications for the function of this enzyme in vivo.

Enhanced biological processes associated with alopecia in polar bears (Ursus maritimus)

Populations of wildlife species worldwide experience incidents of mass morbidity and mortality. Primary or secondary drivers of these events may escape classical detection methods for identifying microbial insults, toxin exposure, or additional stressors. In 2012, 28% of polar bears sampled in a study in the southern Beaufort Sea region of Alaska had varying degrees of alopecia that was concomitant with reduced body condition. Concurrently, elevated numbers of sick or dead ringed seals were detected in the southern Beaufort, Chukchi, and Bering seas in 2012, resulting in the declaration of an unusual mortality event (UME) by the National Oceanic and Atmospheric Administration (NOAA). The primary and possible ancillary causative stressors of these events are unknown, and related physiological changes within individual animals have been undetectable using classical diagnostic methods. Here we present an emerging technology as a potentially guiding investigative approach aimed at elucidating the circumstances responsible for the susceptibility of certain polar bears to observed conditions. Using transcriptomic analysis we identified enhanced biological processes including immune response, viral defense, and response to stress in polar bears with alopecia. Our results support an alternative mechanism of investigation into the causative agents that, when used proactively, could serve as an early indicator for populations and species at risk. We suggest that current or classical methods for investigation into events of unusual morbidity and mortality can be costly, sometimes unfocused, and often inconclusive. Advances in technology allow for implementation of a holistic system of surveillance and investigation that could provide early warning of health concerns in wildlife species important to humans.

Integrating Gene Transcription-Based Biomarkers to Understand Desert Tortoise and Ecosystem Health

Tortoises are susceptible to a wide variety of environmental stressors, and the influence of human disturbances on health and survival of tortoises is difficult to detect. As an addition to current diagnostic methods for desert tortoises, we have developed the first leukocyte gene transcription biomarker panel for the desert tortoise (Gopherus agassizii), enhancing the ability to identify specific environmental conditions potentially linked to declining animal health. Blood leukocyte transcript profiles have the potential to identify physiologically stressed animals in lieu of clinical signs. For desert tortoises, the gene transcript profile included a combination of immune or detoxification response genes with the potential to be modified by biological or physical injury and consequently provide information on the type and magnitude of stressors present in the animal's habitat. Blood from 64 wild adult tortoises at three sites in Clark County, NV, and San Bernardino, CA, and from 19 captive tortoises in Clark County, NV, was collected and evaluated for genes indicative of physiological status. Statistical analysis using a priori groupings indicated significant differences among groups for several genes, while multidimensional scaling and cluster analyses of transcription C T values indicated strong differentiation of a large cluster and multiple outlying individual tortoises or small clusters in multidimensional space. These analyses highlight the effectiveness of the gene panel at detecting environmental perturbations as well as providing guidance in determining the health of the desert tortoise.

Improving power to detect changes in blood miRNA expression by accounting for sources of variability in experimental designs

BACKGROUND

Blood miRNAs are a new promising area of disease research, but variability in miRNA measurements may limit detection of true-positive findings. Here, we measured sources of miRNA variability and determine whether repeated measures can improve power to detect fold-change differences between comparison groups.

METHODS

Blood from healthy volunteers (N = 12) was collected at three time points. The miRNAs were extracted by a method predetermined to give the highest miRNA yield. Nine different miRNAs were quantified using different qPCR assays and analyzed using mixed models to identify sources of variability. A larger number of miRNAs from a publicly available blood miRNA microarray dataset with repeated measures were used for a bootstrapping procedure to investigate effects of repeated measures on power to detect fold changes in miRNA expression for a theoretical case-control study.

RESULTS

Technical variability in qPCR replicates was identified as a significant source of variability (P < 0.05) for all nine miRNAs tested. Variability was larger in the TaqMan qPCR assays (SD = 0.15-0.61) versus the qScript qPCR assays (SD = 0.08-0.14). Inter- and intraindividual and extraction variability also contributed significantly for two miRNAs. The bootstrapping procedure demonstrated that repeated measures (20%-50% of N) increased detection of a 2-fold change for approximately 10% to 45% more miRNAs.

CONCLUSION

Statistical power to detect small fold changes in blood miRNAs can be improved by accounting for sources of variability using repeated measures and choosing appropriate methods to minimize variability in miRNA quantification.

IMPACT

This study demonstrates the importance of including repeated measures in experimental designs for blood miRNA research. See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology."

Dynamic expression of leukocyte innate immune genes in whole blood from horses with lipopolysaccharide-induced acute systemic inflammation

Background

In horses, insights into the innate immune processes in acute systemic inflammation are limited even though these processes may be highly important for future diagnostic and therapeutic advances in high-mortality disease conditions as the systemic inflammatory response syndrome (SIRS) and sepsis. Therefore, the aim of this study was to investigate the expression of 31 selected blood leukocyte immune genes in an equine model of acute systemic inflammation to identify significantly regulated genes and to describe their expression dynamics during a 24-h experimental period. Systemic inflammation was induced in 6 adult horses by the intravenous injection of 1 μg lipopolysaccharide (LPS) per kg btw. Sixteen blood samples were collected for each horse at predetermined intervals and analyzed by reverse transcription quantitative real-time PCR. Post-induction expression levels for each gene were compared with baseline levels.

Results

Systemic inflammation was confirmed by the presence of clinical and hematological changes which were consistent with SIRS. The clinical response to LPS was transient and brief as all horses except one showed unaltered general demeanor after 24 h. Twenty-two leukocyte genes were significantly regulated at at least one time point during the experimental period. By close inspection of the temporal responses the dynamic changes in mRNA abundance revealed a very rapid onset of both pro- and anti-inflammatory mediators and a substantial variation in both expression magnitudes and duration of changes between genes. A majority of the 22 significantly regulated genes peaked within the first 8 h after induction, and an on-going, albeit tightly controlled, regulation was seen after 24 h despite approximate clinical recovery.

Conclusions

This first broad study of gene expressions in blood leukocytes during equine acute LPS-induced systemic inflammation thoroughly characterized a highly regulated and dynamic innate immune response. These results provide new insights into the molecular mechanisms of equine systemic inflammation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-015-0450-5) contains supplementary material, which is available to authorized users.

Combined anti-tumor necrosis factor-α therapy and DMARD therapy in rheumatoid arthritis patients reduces inflammatory gene expression in whole blood compared to DMARD therapy alone

Periodic assessment of gene expression for diagnosis and monitoring in rheumatoid arthritis (RA) may provide a readily available and useful method to detect subclinical disease progression and follow responses to therapy with disease modifying anti-rheumatic agents (DMARDs) or anti-TNF-α therapy. We used quantitative real-time PCR to compare peripheral blood gene expression profiles in active (“unstable”) RA patients on DMARDs, stable RA patients on DMARDs, and stable RA patients treated with a combination of a disease-modifying anti-rheumatoid drug (DMARD) and an anti-TNF-α agent (infliximab or etanercept) to healthy human controls. The expression of 48 inflammatory genes were compared between healthy controls (N = 122), unstable DMARD patients (N = 18), stable DMARD patients (N = 26), and stable patients on combination therapy (N = 20). Expression of 13 genes was very low or undetectable in all study groups. Compared to healthy controls, patients with unstable RA on DMARDs exhibited increased expression of 25 genes, stable DMARD patients exhibited increased expression of 14 genes and decreased expression of five genes, and combined therapy patients exhibited increased expression of six genes and decreased expression of 10 genes. These findings demonstrate that active RA is associated with increased expression of circulating inflammatory markers whereas increases in inflammatory gene expression are diminished in patients with stable disease on either DMARD or anti-TNF-α therapy. Furthermore, combination DMARD and anti-TNF-α therapy is associated with greater reductions in circulating inflammatory gene expression compared to DMARD therapy alone. These results suggest that assessment of peripheral blood gene expression may prove useful to monitor disease progression and response to therapy.

Blood-based gene expression signatures of infants and toddlers with autism

OBJECTIVE

Autism spectrum disorders (ASDs) are highly heritable neurodevelopmental disorders that onset clinically during the first years of life. ASD risk biomarkers expressed early in life could significantly impact diagnosis and treatment, but no transcriptome-wide biomarker classifiers derived from fresh blood samples from children with autism have yet emerged.

METHOD

Using a community-based, prospective, longitudinal method, we identified 60 infants and toddlers at risk for ASDs (autistic disorder and pervasive developmental disorder), 34 at-risk for language delay, 17 at-risk for global developmental delay, and 68 typically developing comparison children. Diagnoses were confirmed via longitudinal follow-up. Each child's mRNA expression profile in peripheral blood mononuclear cells was determined by microarray.

RESULTS

Potential ASD biomarkers were discovered in one-half of the sample and used to build a classifier, with high diagnostic accuracy in the remaining half of the sample.

CONCLUSIONS

The mRNA expression abnormalities reliably observed in peripheral blood mononuclear cells, which are safely and easily assayed in infants, offer the first potential peripheral blood-based, early biomarker panel of risk for autism in infants and toddlers. Future work should verify these biomarkers and evaluate whether they may also serve as indirect indices of deviant molecular neural mechanisms in autism.

Genome-wide miRNA signatures of human longevity

Little is known about the functions of miRNAs in human longevity. Here, we present the first genome-wide miRNA study in long-lived individuals (LLI) who are considered a model for healthy aging. Using a microarray with 863 miRNAs, we compared the expression profiles obtained from blood samples of 15 centenarians and nonagenarians (mean age 96.4 years) with those of 55 younger individuals (mean age 45.9 years). Eighty miRNAs showed aging-associated expression changes, with 16 miRNAs being up-regulated and 64 down-regulated in the LLI relative to the younger probands. Seven of the eight selected aging-related biomarkers were technically validated using quantitative RT-PCR, confirming the microarray data. Three of the eight miRNAs were further investigated in independent samples of 15 LLI and 17 younger participants (mean age 101.5 and 36.9 years, respectively). Our screening confirmed previously published miRNAs of human aging, thus reflecting the utility of the applied approach. The hierarchical clustering analysis of the miRNA microarray expression data revealed a distinct separation between the LLI and the younger controls (P-value < 10(-5) ). The down-regulated miRNAs appeared as a cluster and were more often reported in the context of diseases than the up-regulated miRNAs. Moreover, many of the differentially regulated miRNAs are known to exhibit contrasting expression patterns in major age-related diseases. Further in silico analyses showed enrichment of potential targets of the down-regulated miRNAs in p53 and other cancer pathways. Altogether, synchronized miRNA-p53 activities could be involved in the prevention of tumorigenesis and the maintenance of genomic integrity during aging.

Correlation of pharmacodynamic activity, pharmacokinetics, and anti-product antibody responses to anti-IL-21R antibody therapeutics following IV administration to cynomolgus monkeys

BACKGROUND

Anti-IL-21R antibodies are potential therapeutics for the treatment of autoimmune diseases. This study evaluated correlations between the pharmacodynamic (PD) activity, pharmacokinetics, and anti-product antibody responses of human anti-IL-21R antibodies Ab-01 and Ab-02 following IV administration to cynomolgus monkeys.

METHODS

The PD assay was based on the ability of recombinant human IL-21 (rhuIL-21) to induce expression of the IL-2RA gene in cynomolgus monkey whole blood samples ex vivo. Monkeys screened for responsiveness to rhuIL-21 stimulation using the PD assay, were given a single 10 mg/kg IV dosage of Ab-01, Ab-02, or a control antibody (3/group), and blood samples were evaluated for PD activity (inhibition of IL-2RA expression) for up to 148 days. Anti-IL-21R antibody concentrations and anti-product antibody responses were measured in serum using immunoassays and flow cytometry.

RESULTS

Following IV administration of Ab-01 and Ab-02 to cynomolgus monkeys, PD activity was observed as early as 5 minutes (first time point sampled). This PD activity had good correlation with the serum concentrations and anti-product antibody responses throughout the study. The mean terminal half-life (t1/2) was approximately 10.6 and 2.3 days for Ab-01 and Ab-02, respectively. PD activity was lost at approximately 5-13 weeks for Ab-01 and at approximately 2 weeks for Ab-02, when serum concentrations were relatively low. The estimated minimum concentrations needed to maintain PD activity were approximately 4-6 nM for Ab-01 and approximately 2.5 nM for Ab-02, and were consistent with the respective KD values for binding to human IL-21R. For Ab-01, there was noticeable inter-animal variability in t1/2 values (approximately 6-14 days) and the resulting PD profiles, which correlated with the onset of anti-product antibody formation. While all three Ab-01-dosed animals were positive for anti-Ab-01 antibodies, only one monkey (with the shortest t1/2 and the earliest loss of PD activity) had evidence of neutralizing anti-Ab-01 antibodies. All three Ab-02-dosed monkeys developed neutralizing anti-Ab-02 antibodies.

CONCLUSIONS

For anti-IL-21R antibodies Ab-01 and Ab-02, there was good correlation between PD activity and PK profiles following IV administration to cynomolgus monkeys. Compared with Ab-01, Ab-02 was eliminated markedly faster from the circulation, which correlated with a shorter duration of PD activity.

Increased cytokine production in interleukin-18 receptor alpha-deficient cells is associated with dysregulation of suppressors of cytokine signaling

Since interleukin (IL)-18 is a proinflammatory cytokine, mice lacking IL-18 or its ligand-binding receptor (IL-18R) should exhibit decreased cytokine and chemokine production. Indeed, production of IL-1alpha, IL-6, and MIP-1alpha was reduced in IL-18 knock-out (ko) mouse embryonic fibroblast (MEF)-like cells. Unexpectedly, we observed a paradoxical 10-fold increase in IL-1beta-induced IL-6 production in MEF cells from mice deficient in the IL-18R alpha-chain (IL-18Ralpha) compared with wild type MEF. Similar increases were observed for IL-1alpha, MIP-1alpha, and prostaglandin E2. Likewise, coincubation with a specific IL-18Ralpha-blocking antibody augmented IL-1beta-induced cytokines in wild type and IL-18 ko MEF. Stable lines of IL-18Ralpha-depleted human A549 cells were generated using shRNA, resulting in an increase of IL-1beta-induced IL-1alpha, IL-6, and IL-8 compared to scrambled small hairpin RNA. In addition, we silenced IL-18Ralpha with small interfering RNA in primary human blood cells and observed up to 4-fold increases in the secretion of lipopolysaccharide- and IL-12/IL-18-induced IL-1beta, IL-6, interferon-gamma, and CD40L. Mechanistically, despite increases in Stat1 and IL-6, induction of SOCS1 and -3 (suppressor of cytokine signaling 1 and 3) was markedly reduced in the absence of IL-18Ralpha. Consistent with these observations, activation of the p38alpha/beta and ERK1/2 MAPKs and of protein kinase B/Akt increased in IL-18Ralpha ko MEF, whereas the negative feedback kinase MSK2 was more active in IL-18 ko cells. These data reveal a role for SOCS1 and -3 in the seemingly paradoxical hyperresponsive state in cells deficient in IL-18Ralpha, supporting the concept that IL-18Ralpha participates in both pro- and anti-inflammatory responses and that an endogenous ligand engages IL-18Ralpha to deliver an inhibitory signal.

A longitudinal study of gene expression in healthy individuals

Background

The use of gene expression in venous blood either as a pharmacodynamic marker in clinical trials of drugs or as a diagnostic test requires knowledge of the variability in expression over time in healthy volunteers. Here we defined a normal range of gene expression over 6 months in the blood of four cohorts of healthy men and women who were stratified by age (22–55 years and > 55 years) and gender.

Methods

Eleven immunomodulatory genes likely to play important roles in inflammatory conditions such as rheumatoid arthritis and infection in addition to four genes typically used as reference genes were examined by quantitative reverse transcription-polymerase chain reaction (qRT-PCR), as well as the full genome as represented by Affymetrix HG U133 Plus 2.0 microarrays.

Results

Gene expression levels as assessed by qRT-PCR and microarray were relatively stable over time with ~2% of genes as measured by microarray showing intra-subject differences over time periods longer than one month. Fifteen genes varied by gender. The eleven genes examined by qRT-PCR remained within a limited dynamic range for all individuals. Specifically, for the seven most stably expressed genes (CXCL1, HMOX1, IL1RN, IL1B, IL6R, PTGS2, and TNF), 95% of all samples profiled fell within 1.5–2.5 Ct, the equivalent of a 4- to 6-fold dynamic range. Two subjects who experienced severe adverse events of cancer and anemia, had microarray gene expression profiles that were distinct from normal while subjects who experienced an infection had only slightly elevated levels of inflammatory markers.

Conclusion

This study defines the range and variability of gene expression in healthy men and women over a six-month period. These parameters can be used to estimate the number of subjects needed to observe significant differences from normal gene expression in clinical studies. A set of genes that varied by gender was also identified as were a set of genes with elevated expression in a subject with iron deficiency anemia and another subject being treated for lung cancer.

Alpha-1-antitrypsin is an endogenous inhibitor of proinflammatory cytokine production in whole blood

Several observations suggest endogenous suppressors of inflammatory mediators are present in human blood. alpha-1-Antitrypsin (AAT) is the most abundant serine protease inhibitor in blood, and AAT possesses anti-inflammatory activity in vitro and in vivo. Here, we show that in vitro stimulation of whole blood from persons with a genetic AAT deficiency resulted in enhanced cytokine production compared with blood from healthy subjects. Using whole blood from healthy subjects, dilution of blood with RPMI tissue-culture medium, followed by incubation for 18 h, increased spontaneous production of IL-8, TNF-alpha, IL-1 beta, and IL-1R antagonist (IL-1Ra) significantly, compared with undiluted blood. Dilution-induced cytokine production suggested the presence of one or more circulating inhibitors of cytokine synthesis present in blood. Serially diluting blood with tissue-culture medium in the presence of cytokine stimulation with heat-killed Staphylococcus epidermidis (S. epi) resulted in 1.2- to 55-fold increases in cytokine production compared with S. epi stimulation alone. Diluting blood with autologous plasma did not increase the production of IL-8, TNF-alpha, IL-1 beta, or IL-1Ra, suggesting that the endogenous, inhibitory activity of blood resided in plasma. In whole blood, diluted and stimulated with S. epi, exogenous AAT inhibited IL-8, IL-6, TNF-alpha, and IL-1 beta significantly but did not suppress induction of the anti-inflammatory cytokines IL-1Ra and IL-10. These ex vivo and in vitro observations suggest that endogenous AAT in blood contributes to the suppression of proinflammatory cytokine synthesis.

Quality-Controlled Measurement Methods for Quantification of Variations in Transcript Abundance in Whole Blood Samples from Healthy Volunteers

Background: Transcript abundance (TA) measurement in whole blood frequently is conducted to identify potential biomarkers for disease risk and to predict or monitor drug response. Potential biomarkers discovered in this way must be validated by quantitative technology. In this study we assessed the use of standardized reverse transcription PCR (StaRT-PCR™) to validate potential biomarkers discovered through whole blood TA profiling.

Methods: For each of 15 healthy volunteers, 6 blood samples were obtained, including 3 samples at each of 2 separate visits. Total variation in TA for each gene was partitioned into replicate, sample, visit, study participant, and residual components.

Results: Variation originating from technical processing was &lt;5% of total combined variation and was primarily preanalytical. Interindividual biological sample variation was larger than technical variation. For 12 of 19 tests, the distribution of measured values was gaussian (Shapiro–Wilks test).

Conclusion: For control or diseased population groups with variation rates as low as those observed in this control group, 17 individuals per group would be required to detect 1 SD change with 80% power with a 2-sided α = 0.05 statistical test for mean differences.