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Relationship: 1589

Title

A descriptive phrase which clearly defines the two KEs being considered and the sequential relationship between them (i.e., which is upstream, and which is downstream). More help

Increased transcription of genes encoding acute phase proteins leads to Systemic acute phase response

Upstream event
The causing Key Event (KE) in a Key Event Relationship (KER). More help
Downstream event
The responding Key Event (KE) in a Key Event Relationship (KER). More help

Key Event Relationship Overview

The utility of AOPs for regulatory application is defined, to a large extent, by the confidence and precision with which they facilitate extrapolation of data measured at low levels of biological organisation to predicted outcomes at higher levels of organisation and the extent to which they can link biological effect measurements to their specific causes.Within the AOP framework, the predictive relationships that facilitate extrapolation are represented by the KERs. Consequently, the overall WoE for an AOP is a reflection in part, of the level of confidence in the underlying series of KERs it encompasses. Therefore, describing the KERs in an AOP involves assembling and organising the types of information and evidence that defines the scientific basis for inferring the probable change in, or state of, a downstream KE from the known or measured state of an upstream KE. More help

AOPs Referencing Relationship

AOP Name Adjacency Weight of Evidence Quantitative Understanding Point of Contact Author Status OECD Status
Substance interaction with lung resident cell membrane components leading to atherosclerosis via acute phase response adjacent High Moderate Ulla Vogel (send email) Under development: Not open for comment. Do not cite Under Development

Taxonomic Applicability

Latin or common names of a species or broader taxonomic grouping (e.g., class, order, family) that help to define the biological applicability domain of the KER.In general, this will be dictated by the more restrictive of the two KEs being linked together by the KER.  More help
Term Scientific Term Evidence Link
mouse Mus musculus High NCBI
human Homo sapiens High NCBI

Sex Applicability

An indication of the the relevant sex for this KER. More help
Sex Evidence
Male High
Female High

Life Stage Applicability

An indication of the the relevant life stage(s) for this KER.  More help
Term Evidence
All life stages High

Key Event Relationship Description

Provides a concise overview of the information given below as well as addressing details that aren’t inherent in the description of the KEs themselves. More help

This KER presents the association between the increased transcription of genes encoding acute phase proteins (Key event 1438) in different tissues and the induction of systemic acute phase response (Key event 1439). Acute phase proteins are expressed in the liver, and in several other tissues including lung (Gabay & Kushner, 1999; Hadrup et al., 2020; NCBI, 2023; Saber et al., 2014; Urieli-Shoval et al., 1998). During acute phase response several changes occur, including variations in plasma concentration of acute phase proteins. The two major acute phase proteins are C-reactive protein and serum amyloid A (Gabay & Kushner, 1999). The evidence of the KER presented is based on animal studies (mice).

Evidence Collection Strategy

Include a description of the approach for identification and assembly of the evidence base for the KER. For evidence identification, include, for example, a description of the sources and dates of information consulted including expert knowledge, databases searched and associated search terms/strings.  Include also a description of study screening criteria and methodology, study quality assessment considerations, the data extraction strategy and links to any repositories/databases of relevant references.Tabular summaries and links to relevant supporting documentation are encouraged, wherever possible. More help

Targeted literature search focusing primarily on humans and mice.

Evidence Supporting this KER

Addresses the scientific evidence supporting KERs in an AOP setting the stage for overall assessment of the AOP. More help
Biological Plausibility
Addresses the biological rationale for a connection between KEupstream and KEdownstream.  This field can also incorporate additional mechanistic details that help inform the relationship between KEs, this is useful when it is not practical/pragmatic to represent these details as separate KEs due to the difficulty or relative infrequency with which it is likely to be measured.   More help

The biological plausibility is high. After gene expression of acute phase proteins in tissues during inflammatory conditions, mRNA is translated and folded into proteins (Alberts, 2017). These proteins are then release to the systemic circulation (Van Eeden, Leipsic, Paul Man, & Sin, 2012). Serum Amyloid A (SAA) and C-reactive protein (CRP) are the two major acute phase proteins in humans (Gabay & Kushner, 1999). CRP is routinely measured in blood, serum or plasma and used as marker of systemic inflammation. CRP has a half-life of 19 h in blood, also in clinical settings (Rajab, Hart, & Potempa, 2020). The origin of biosynthesis of proteins in blood cannot be directly established. Biosynthesis of acute phase proteins is thus documented by evidence of transcription. Thus, in one study, SAA mRNA was detected in hepatoma cell lines, epithelial cell lines, an endothelial cell line, and a fibroblast cell line (Steel, Donoghue, O'Neill, Uhlar, & Whitehead, 1996). The timing and kinetics of tissue biosynthesis, systemic availability and systemically increased acute phase protein levels likely depends on the stressor, the magnitude of the acute phase response and the organ in question among others.

Uncertainties and Inconsistencies
Addresses inconsistencies or uncertainties in the relationship including the identification of experimental details that may explain apparent deviations from the expected patterns of concordance. More help

Although it is suggested that acute phase proteins are mainly produced in the liver (Gabay & Kushner, 1999), it has been shown that in mice, the liver has little upregulation of Saa genes after exposure to ultrafine carbon particles or diesel exhaust particle. In contrast, in the lung  there is a marked expression of Saa3 mRNA (Saber et al., 2009; Saber et al., 2013).

Some studies show that the increase of Saa gene expression in lung or liver tissue does not translate into an increase in plasma SAA concentration (Bendtsen et al., 2019; Bengtson et al., 2017; Hadrup et al., 2019). This might be due to a protein concentration below the methods detection levels (Hadrup et al., 2019), while measuring gene expression provides a larger dynamic range. It may also reflect that plasma background levels of SAA are higher than the transcriptional background levels in tissues, reflecting that larger sample sizes may be needed to detect slight increases in protein levels in serum samples. Additionally, it may reflect a dilution of the SAA concentration when SAA3 is secreted from lung tissue into systemic circulation. Thus, following inhalation exposure to nano-titanium dioxide, Saa3 mRNA levels were increased 4.7-fold in lung tissue, and SAA3 protein levels were approximately doubled in lung tissue (Halappanavar et al., 2011). However, more than 5-fold increase in Saa3 mRNA levels in lung tissue are required for detection of SAA3 in serum. Thus, 12-20 fold increases in lung Saa3 mRNA levels were parallelled with ca. 3-fold increases in SAA3 serum levels in one study (Bendtsen et al., 2019).

The table below presents inconsistencies for this KER, where transcription of genes encoding acute phase proteins has been observed, while systemic acute phase response was not observed. The transcription of genes encoding acute phase proteins was measured in tissues, while systemic acute phase response is measured as the concentration of acute phase proteins in blood plasma or serum.

Species

Stressor

Transcription of genes encoding acute phase proteins

Systemic acute phase response

Reference

Mouse

Reduced graphene oxide

Yes, increased mRNA expression of Saa3 in lung tissue, 3 days after exposure to 162 µg.  No changes in gene expression of Saa1 in liver tissue.

No, no change in serum amyloid A (SAA)3 plasma concentration 3 days after exposure.

(Bengtson et al., 2017)

Mouse

Particulate matter from commercial airport

Yes, increased expression of Saa3 mRNA in lung tissue after 1 day of exposure to 18 and 54 µg.

No effect after 28 and 90 days.

No change in plasma SAA3.

(Bendtsen et al., 2019)

Mouse

Carbon black

Yes, increased expression of Saa3 mRNA in lung tissue at day 1 and day 90.

No change in plasma SAA3.

(Bendtsen et al., 2019)

Mouse

Uncoated zinc oxide nanoparticles

Yes, increase on Saa3 mRNA in lung tissue 1 day after exposure to 2 µg. No effect 3 and 28 days after exposure.

No effect on plasma SAA3.

(Hadrup et al., 2019)

Mouse

Coated zinc oxide nanoparticles

Yes, increase on Saa3 mRNA in lung tissue 1 day after exposure to 0.7 and 2 µg. No effect 3 and 28 days after exposure.

No effect on plasma SAA3.

(Hadrup et al., 2019)

Mouse

Zinc oxide

Yes, increased Saa1 mRNA expression in liver tissue 1 day after exposure to 0.7 µg. No change in Saa3 mRNA expression in lung tissue.

No change in plasma SAA3 or SAA1/2 levels.

(Gutierrez et al., 2023)

Known modulating factors

This table captures specific information on the MF, its properties, how it affects the KER and respective references.1.) What is the modulating factor? Name the factor for which solid evidence exists that it influences this KER. Examples: age, sex, genotype, diet 2.) Details of this modulating factor. Specify which features of this MF are relevant for this KER. Examples: a specific age range or a specific biological age (defined by...); a specific gene mutation or variant, a specific nutrient (deficit or surplus); a sex-specific homone; a certain threshold value (e.g. serum levels of a chemical above...) 3.) Description of how this modulating factor affects this KER. Describe the provable modification of the KER (also quantitatively, if known). Examples: increase or decrease of the magnitude of effect (by a factor of...); change of the time-course of the effect (onset delay by...); alteration of the probability of the effect; increase or decrease of the sensitivity of the downstream effect (by a factor of...) 4.) Provision of supporting scientific evidence for an effect of this MF on this KER. Give a list of references.  More help
Response-response Relationship
Provides sources of data that define the response-response relationships between the KEs.  More help

The expression of Saa3 mRNA levels in lung tissue (Key event 1438) correlates with concentration of SAA3 plasma protein levels (Key event 1439), in female C57BL/6J mice 1 day after intratracheal instillation of metal oxide nanomaterials (Figure 1). The Pearson’s correlation coefficient was 0.89 (p<0.001) between log-transformed Saa3 mRNA levels in lung tissue and log-transformed SAA3 plasma protein levels (Gutierrez et al., 2023).

Figure 1. Correlations between Saa3 mRNA levels in lung tissue and SAA3 plasma protein levels in mice, 1 day after exposure to nanomaterials. Reproduced from Gutierrez et al. (2023).

Time-scale
Information regarding the approximate time-scale of the changes in KEdownstream relative to changes in KEupstream (i.e., do effects on KEdownstream lag those on KEupstream by seconds, minutes, hours, or days?). More help

After exposure to titanium dioxide nanoparticles in mice, expression of Saa1 mRNA in the liver is short lasting, while expression of Saa3 mRNA in lung tissue is longer lasting, as it has been observed 28 days after exposure (Wallin et al., 2017).

After exposure to multiwalled carbon nanotubes and metal oxides, it has been observed that expression of Saa1 and Saa3 in liver and lung tissue can be elevated 28 days after exposure, however in most cases there is no increase in plasma SAA1/2 nor SAA3 levels past day 1 after exposure (Poulsen et al., 2017; Gutierrez et al., 2023)

Known Feedforward/Feedback loops influencing this KER
Define whether there are known positive or negative feedback mechanisms involved and what is understood about their time-course and homeostatic limits. More help

Domain of Applicability

A free-text section of the KER description that the developers can use to explain their rationale for the taxonomic, life stage, or sex applicability structured terms. More help

The acute phase response is present in vertebrate species (Cray, Zaias, & Altman, 2009), including common animal species such as horse, cow, dog, cat, pig, goat, and rat. In addition, serum amyloid A has been conserved in mammals throughout evolution and has been described in humans, mice, dogs, horses, among others (Uhlar & Whitehead, 1999).

The presence of acute phase proteins in blood does not inform about the tissue of origin. The prevailing general view of acute-phase proteins (APPs) has been that they are produced by the liver in response to the stress of the body as part of a systemic acute phase response. However, acute phase protein transcription may be induced in different tissues (Hamar, 2022) including lung tissue following pulmonary exposure to different agents (Gutierrez et al., 2023; Hadrup et al., 2020; Saber et al., 2014).

CRP levels are used in the clinical setting as marker of inflammation, thus illustrating the applicability across sex and age in humans.

Mice express several Saa isoforms in lung tissue (Saa1, Saa2 and Saa3), whereas humans have only one inducible Saa isoform, Saa1. In mice, Saa1, Saa2 and Saa3 are all expressed as part of a particle-induced pulmonary acute phase response, and since Saa3 is the most differentially regulated Saa isoform, Saa3 is used as a proxy for Saa expression (Saber et al., 2014). In contrast, Saa1 is the most differentially expressed isoform in mouse liver following  pulmonary particle-induced acute phase response (Saber et al., 2014). Humans have only one inducible Saa isoform, Saa1. Differential expression of Saa1 and CRP have been shown in human lung samples (Calero et al., 2014).

References

List of the literature that was cited for this KER description. More help

Alberts, B. (2017). Molecular biology of the cell (Sixth edition. ed.). Boca Raton, FL: CRC Press, an imprint of Garland Science.

Bendtsen, K. M., Brostrom, A., Koivisto, A. J., Koponen, I., Berthing, T., Bertram, N., . . . Vogel, U. (2019). Airport emission particles: exposure characterization and toxicity following intratracheal instillation in mice. Part Fibre Toxicol, 16(1), 23. doi:10.1186/s12989-019-0305-5

Bengtson, S., Knudsen, K. B., Kyjovska, Z. O., Berthing, T., Skaug, V., Levin, M., . . . Vogel, U. (2017). Differences in inflammation and acute phase response but similar genotoxicity in mice following pulmonary exposure to graphene oxide and reduced graphene oxide. PLoS One, 12(6), e0178355. doi:10.1371/journal.pone.0178355

Bourdon, J. A., Halappanavar, S., Saber, A. T., Jacobsen, N. R., Williams, A., Wallin, H., . . . Yauk, C. L. (2012). Hepatic and pulmonary toxicogenomic profiles in mice intratracheally instilled with carbon black nanoparticles reveal pulmonary inflammation, acute phase response, and alterations in lipid homeostasis. Toxicol Sci, 127(2), 474-484. doi:10.1093/toxsci/kfs119

Calero, C., Arellano, E., Lopez-Villalobos, J. L., Sanchez-Lopez, V., Moreno-Mata, N., & Lopez-Campos, J. L. (2014). Differential expression of C-reactive protein and serum amyloid A in different cell types in the lung tissue of chronic obstructive pulmonary disease patients. BMC Pulm Med, 14, 95. doi:10.1186/1471-2466-14-95

Christophersen, D. V., Moller, P., Thomsen, M. B., Lykkesfeldt, J., Loft, S., Wallin, H., . . . Jacobsen, N. R. (2021). Accelerated atherosclerosis caused by serum amyloid A response in lungs of ApoE(-/-) mice. FASEB J, 35(3), e21307. doi:10.1096/fj.202002017R

Cray, C., Zaias, J., & Altman, N. H. (2009). Acute phase response in animals: a review. Comp Med, 59(6), 517-526. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/20034426

Danielsen, P. H., Bendtsen, K. M., Knudsen, K. B., Poulsen, S. S., Stoeger, T., & Vogel, U. (2021). Nanomaterial- and shape-dependency of TLR2 and TLR4 mediated signaling following pulmonary exposure to carbonaceous nanomaterials in mice. Part Fibre Toxicol, 18(1), 40. doi:10.1186/s12989-021-00432-z

Erdely, A., Liston, A., Salmen-Muniz, R., Hulderman, T., Young, S. H., Zeidler-Erdely, P. C., . . . Simeonova, P. P. (2011). Identification of systemic markers from a pulmonary carbon nanotube exposure. J Occup Environ Med, 53(6 Suppl), S80-86. doi:10.1097/JOM.0b013e31821ad724

Gabay, C., & Kushner, I. (1999). Acute-phase proteins and other systemic responses to inflammation. N Engl J Med, 340(6), 448-454. doi:10.1056/NEJM199902113400607

Gutierrez, C. T., Loizides, C., Hafez, I., Brostrom, A., Wolff, H., Szarek, J., . . . Vogel, U. (2023). Acute phase response following pulmonary exposure to soluble and insoluble metal oxide nanomaterials in mice. Part Fibre Toxicol, 20(1), 4. doi:10.1186/s12989-023-00514-0

Hadrup, N., Rahmani, F., Jacobsen, N. R., Saber, A. T., Jackson, P., Bengtson, S., . . . Vogel, U. (2019). Acute phase response and inflammation following pulmonary exposure to low doses of zinc oxide nanoparticles in mice. Nanotoxicology, 13(9), 1275-1292. doi:10.1080/17435390.2019.1654004

Hadrup, N., Zhernovkov, V., Jacobsen, N. R., Voss, C., Strunz, M., Ansari, M., . . . Vogel, U. (2020). Acute Phase Response as a Biological Mechanism-of-Action of (Nano)particle-Induced Cardiovascular Disease. Small, 16(21), e1907476. doi:10.1002/smll.201907476

Halappanavar, S., Jackson, P., Williams, A., Jensen, K. A., Hougaard, K. S., Vogel, U., . . . Wallin, H. (2011). Pulmonary response to surface-coated nanotitanium dioxide particles includes induction of acute phase response genes, inflammatory cascades, and changes in microRNAs: a toxicogenomic study. Environ Mol Mutagen, 52(6), 425-439. doi:10.1002/em.20639

Hamar, P. (2022). A New Role of Acute Phase Proteins: Local Production Is an Ancient, General Stress-Response System of Mammalian Cells. Int J Mol Sci, 23(6). doi:10.3390/ijms23062972

Poulsen, S. S., Knudsen, K. B., Jackson, P., Weydahl, I. E., Saber, A. T., Wallin, H., & Vogel, U. (2017). Multi-walled carbon nanotube-physicochemical properties predict the systemic acute phase response following pulmonary exposure in mice. PLoS One, 12(4), e0174167. doi:10.1371/journal.pone.0174167

Poulsen, S. S., Saber, A. T., Mortensen, A., Szarek, J., Wu, D., Williams, A., . . . Vogel, U. (2015). Changes in cholesterol homeostasis and acute phase response link pulmonary exposure to multi-walled carbon nanotubes to risk of cardiovascular disease. Toxicol Appl Pharmacol, 283(3), 210-222. doi:10.1016/j.taap.2015.01.011

Poulsen, S. S., Saber, A. T., Williams, A., Andersen, O., Kobler, C., Atluri, R., . . . Vogel, U. (2015). MWCNTs of different physicochemical properties cause similar inflammatory responses, but differences in transcriptional and histological markers of fibrosis in mouse lungs. Toxicol Appl Pharmacol, 284(1), 16-32. doi:10.1016/j.taap.2014.12.011

Rajab, I. M., Hart, P. C., & Potempa, L. A. (2020). How C-Reactive Protein Structural Isoforms With Distinctive Bioactivities Affect Disease Progression. Front Immunol, 11, 2126. doi:10.3389/fimmu.2020.02126

Saber, A. T., Halappanavar, S., Folkmann, J. K., Bornholdt, J., Boisen, A. M., Moller, P., . . . Wallin, H. (2009). Lack of acute phase response in the livers of mice exposed to diesel exhaust particles or carbon black by inhalation. Part Fibre Toxicol, 6, 12. doi:10.1186/1743-8977-6-12

Saber, A. T., Jacobsen, N. R., Jackson, P., Poulsen, S. S., Kyjovska, Z. O., Halappanavar, S., . . . Vogel, U. (2014). Particle-induced pulmonary acute phase response may be the causal link between particle inhalation and cardiovascular disease. Wiley Interdiscip Rev Nanomed Nanobiotechnol, 6(6), 517-531. doi:10.1002/wnan.1279

Saber, A. T., Lamson, J. S., Jacobsen, N. R., Ravn-Haren, G., Hougaard, K. S., Nyendi, A. N., . . . Vogel, U. (2013). Particle-induced pulmonary acute phase response correlates with neutrophil influx linking inhaled particles and cardiovascular risk. PLoS One, 8(7), e69020. doi:10.1371/journal.pone.0069020

Steel, D. M., Donoghue, F. C., O'Neill, R. M., Uhlar, C. M., & Whitehead, A. S. (1996). Expression and regulation of constitutive and acute phase serum amyloid A mRNAs in hepatic and non-hepatic cell lines. Scand J Immunol, 44(5), 493-500. doi:10.1046/j.1365-3083.1996.d01-341.x

Uhlar, C. M., & Whitehead, A. S. (1999). Serum amyloid A, the major vertebrate acute-phase reactant. Eur J Biochem, 265(2), 501-523. doi:10.1046/j.1432-1327.1999.00657.x