Regulation of collagen turnover in human skin fibroblasts exposed to a gadolinium-based contrast agent

Toxicity Mechanisms of Gadolinium and Gadolinium-Based Contrast Agents-A Review

Gadolinium-based contrast agents (GBCAs) have been used for more than 30 years to improve magnetic resonance imaging, a crucial tool for medical diagnosis and treatment monitoring across multiple clinical settings. Studies have shown that exposure to GBCAs is associated with gadolinium release and tissue deposition that may cause short- and long-term toxicity in several organs, including the kidney, the main excretion organ of most GBCAs. Considering the increasing prevalence of chronic kidney disease worldwide and that most of the complications following GBCA exposure are associated with renal dysfunction, the mechanisms underlying GBCA toxicity, especially renal toxicity, are particularly important. A better understanding of the gadolinium mechanisms of toxicity may contribute to clarify the safety and/or potential risks associated with the use of GBCAs. In this work, a review of the recent literature concerning gadolinium and GBCA mechanisms of toxicity was performed.

Skin Toxicity After Exposure to Gadolinium-Based Contrast Agents in Normal Renal Function, Using Clinical Approved Doses: Current Status of Preclinical and Clinical Studies

OBJECTIVES

The aim of this study was to summarize the current preclinical and clinical evidence on the association between exposure to gadolinium (Gd) compounds and skin toxicity in a setting similar to clinical practice.

MATERIALS AND METHODS

A search of MEDLINE and PubMed references from January 2000 to December 2022 was performed using keywords related to gadolinium deposition and its effects on the skin, such as "gadolinium," "gadolinium-based contrast agents," "skin," "deposition," and "toxicity." In addition, cross-referencing was added when appropriate. For preclinical in vitro studies, we included all the studies that analyzed the response of human dermal fibroblasts to exposure to various gadolinium compounds. For preclinical animal studies and clinical studies, we included only those that analyzed animals or patients with preserved renal function (estimated glomerular filtration rate >30 mL/min/1.73 m 2 ), using a dosage of gadolinium-based contrast agents (GBCAs) similar to that commonly applied (0.1 mmol/kg).

RESULTS

Forty studies were selected. Preclinical findings suggest that Gd compounds can produce profibrotic responses in the skin in vitro, through the activation and proliferation of dermal fibroblasts and promoting their myofibroblast differentiation. Gadolinium influences the process of collagen production and the collagen content of skin, by increasing the levels of matrix metalloproteinase-1 and tissue inhibitor of metalloproteinase-1. Preclinical animal studies show that Gd can deposit in the skin with higher concentrations when linear GBCAs are applied. However, these deposits decrease over time and are not associated with obvious macroscopic or histological modifications. The clinical relevance of GBCAs in inducing small fiber neuropathy remains to be determined. Clinical studies show that Gd is detectable in the skin and hair of subjects with normal renal function in higher concentrations after intravenous administration of linear compared with macrocyclic GBCA. However, these deposits decrease over time and are not associated with cutaneous or histological modifications. Also, subclinical dermal involvement related to linear GBCA exposure may be detectable on brain MRI. There is no conclusive evidence to support a causal relationship between GBCA administration at the clinical dose and cutaneous manifestations in patients with normal renal function.

CONCLUSIONS

Gadolinium can produce profibrotic responses in the skin, especially acting on fibroblasts, as shown by preclinical in vitro studies. Gadolinium deposits are detectable in the skin even in subjects with normal renal function with higher concentrations when linear GBCAs are used, as confirmed by both preclinical animal and human studies. There is no proof to date of a cause-effect relationship between GBCA administration at clinical doses and cutaneous consequences in patients with normal renal function. Multiple factors, yet to be determined, should be considered for sporadic patients with normal renal function who develop clinical skin manifestations temporally related to GBCA administration.

Gadolinium: pharmacokinetics and toxicity in humans and laboratory animals following contrast agent administration

Gadolinium-based contrast agents (GBCAs) have transformed magnetic resonance imaging (MRI) by facilitating the use of contrast-enhanced MRI to allow vital clinical diagnosis in a plethora of disease that would otherwise remain undetected. Although over 500 million doses have been administered worldwide, scientific research has documented the retention of gadolinium in tissues, long after exposure, and the discovery of a GBCA-associated disease termed nephrogenic systemic fibrosis, found in patients with impaired renal function. An understanding of the pharmacokinetics in humans and animals alike are pivotal to the understanding of the distribution and excretion of gadolinium and GBCAs, and ultimately their potential retention. This has been well studied in humans and more so in animals, and recently there has been a particular focus on potential toxicities associated with multiple GBCA administration. The purpose of this review is to highlight what is currently known in the literature regarding the pharmacokinetics of gadolinium in humans and animals, and any toxicity associated with GBCA use.

Neutrophil elastase in the development of nephrogenic systemic fibrosis (NSF)-like skin lesion in renal failure mouse model

Although neutrophil elastase (NE) may play a role in lung fibrosis and liver fibrosis, NE involvement in the development of nephrogenic systemic fibrosis has been unclear. We investigated the involvement of NE in the development of nephrogenic systemic fibrosis-like skin lesions post-injections of linear gadolinium-based contrast agents in renal failure mouse models. Renal failure mouse models were randomly divided into three groups: control group (saline), gadodiamide group, and gadopentetate group. Each solution was intravenously administered three times per week for three weeks. The mice were observed daily for skin lesions. Quantification of skin lesions, infiltrating inflammatory cells, and profibrotic cytokines in the affected skin was performed by immunostaining and reverse-transcription polymerase chain reaction (RT-PCR). Blood samples were collected from the facial vein to quantify NE enzymatic activity. The 158Gd concentrations in each sample were quantified using inductively coupled plasma mass spectrometry (ICP-MS). In the gadodiamide group, the mRNA expression of fibrotic markers was increased in the skin lesions compared to the control group. In the gadopentetate group, only collagen 1α and TGF-β mRNA expression were higher than in the control group. The expression of CD3+, CD68+, NE cells and the NE activity in the blood serum were significantly higher in the gadodiamide and gadopentetate groups compared to the control group. Gadolinium concentration in the skin of the gadodiamide group was significantly higher than the gadopentetate group, while almost no traces of gadolinium were found in the control group. Although gadopentetate and gadodiamide affected the fibrotic markers in the skin differently, NE may be involved in the development of fibrosis linked to the GBCAs injections in renal failure mouse models.

Antiwrinkle and antimelanogenesis activity of the ethanol extracts of Lespedeza cuneata G. Don for development of the cosmeceutical ingredients

To develop the ingredient with the cosmeceutical function, the antiwrinkle and antimelanogenesis effects of the ethanol extract of Lespedeza cuneata G. Don were investigated. DPPH radical scavenging activity was significantly increased with the extract of L. cuneata G. Don. Cell viability on CCD986Sk human fibroblast was also increased by the ethanol extract of L. cuneata G. Don. The inhibitory function of the extract of L. cuneata G. Don on collagenase, elastase, and tyrosinase was evaluated. Protein expression level of Claudin-1, Occludin, and ZO-1 was up-regulated in HaCaT human keratinocyte by the extract of L. cuneata G. Don. In addition, the extract of L. cuneata G. Don inhibited melanin synthesis in B16F10 murine melanoma cells by decreasing MITF, TRP1, and TRP2 protein levels and increasing the phosphorylated Erk and Akt. Thus, these findings would be useful for developing the new cosmeceutical formulations based on the extract of L. cuneata G. Don.

Comparative study of the effects of gadolinium chloride and gadolinium - based magnetic resonance imaging contrast agent on freshwater mussel, Dreissena polymorpha

Gadolinium (Gd), a metal of the lanthanide series used in various industrial and medical purposes is released into the aquatic environment. However, there are few aquatic toxicological studies addressing environmental effects of Gd which remains unknown in aquatic animals. Therefore, this study aimed to compare the effects of GdCl₃ and a gadolinium-based MRI contrast agent (Omniscan), in zebra mussels after 28 days through a multibiomarker approach. Data revealed that after GdCl₃ exposure, the mRNA level of metallothionein (MT) was modulated, those of cytochrome c oxidase (CO1) and superoxide dismutase (SOD) were increased, while gene expressions of catalase (CAT) and glutathione-S-transferase (GST) were downregulated. Furthermore, neither lipoperoxidation (LPO) nor genotoxicity were detected but only a decrease in the cyclooxygenase (COX) activity was observed. In addition, a significant correlation was found between biomarkers and bioaccumulated Gd, suggesting that mitochondrial and anti-inflammatory pathways were triggered with GdCl₃. By opposition, the contrasting agent formulation induced downregulation of SOD, CAT, GST and CO1, a decrease in the level of LPO and an increase in the GST and COX activities. This suggests that the chelated form of Gd did not promote reactive oxygen species (ROS) production and exhibits antioxidant and proinflammatory effects in mussels. Therefore, this study revealed that ionic and the chelated form of Gd influence different cellular pathways to initiate cellular changes.

Gadolinium-Induced Fibrosis

Gadolinium-based contrast agents (GBCAs), once believed to be safe for patients with renal disease, have been strongly associated with nephrogenic systemic fibrosis (NSF), a severe systemic fibrosing disorder that predominantly afflicts individuals with advanced renal dysfunction. We provide a historical perspective on the appearance and disappearance of NSF, including its initial recognition as a discrete clinical entity, its association with GBCA exposure, and the data supporting a causative relationship between GBCA exposure and NSF. On the basis of this body of evidence, we propose that the name gadolinium-induced fibrosis (GIF) more accurately reflects the totality of knowledge regarding this disease. Use of high-risk GBCAs, such as formulated gadodiamide, should be avoided in patients with renal disease. Restriction of GBCA use in this population has almost completely eradicated new cases of this debilitating condition. Emerging antifibrotic therapies may be useful for patients who suffer from GIF.

Balanced regulation of the CCN family of matricellular proteins: a novel approach to the prevention and treatment of fibrosis and cancer

The CCN family of matricellular signaling proteins is emerging as a unique common link across multiple diseases and organs related to injury and repair. They are now being shown to play a central role in regulating the pathways to the initiation and resolution of normal wound healing and fibrosis in response to multiple forms of injury. Similarly, it is also emerging that they play a key role in regulating the establishment, growth, metastases and tissue regeneration in many forms of cancer via the interaction of cancer cells with the tumor stroma. Evidence has been recently provided that these proteins do not act independently but are co-regulated working in a yin/yang manner to alter the outcome of both normal physiological processes as well as pathology. The purpose of this review is to twofold. First, it will summarize work to date supporting CCN2 as a therapeutic target in the formation and progression of renal, skin, and other organ fibrosis, as well as cancer stroma formation. Second, it will highlight recent evidence for CCN3 as a counter-regulator and a potential therapeutic agent in these diseases with an exciting, novel potential to both treat and then restore tissue homeostasis in those afflicted by these devastating disorders.

Understanding nephrogenic systemic fibrosis

Nephrogenic systemic fibrosis (NSF) is a rare and a debilitating disease noted uncommonly in patients with impaired renal function when exposed to low-stability gadolinium-based contrast agents (Gd-CAs). According to experimental studies, cytokines released by the stimulation of effector cells such as skin macrophages and peripheral blood monocytes activate circulating fibroblasts which play a major role in the development of NSF lesions. The presence of permissive factors, presumably, provides an environment conducive to facilitate the process of fibrosis. Multiple treatment modalities have been tried with variable success rates. More research is necessary to elucidate the underlying pathophysiological mechanisms which could potentially target the initial steps of fibrosis in these patients. This paper attempts to collate the inferences from the in vivo and in vitro experiments to the clinical observations to understand the pathogenesis of NSF. Schematic representations of receptor-mediated molecular pathways of activation of macrophages and fibroblasts by gadolinium and the final pathway to fibrosis are incorporated in the discussion.

Gadolinium-induced fibrosis is counter-regulated by CCN3 in human dermal fibroblasts: a model for potential treatment of nephrogenic systemic fibrosis

We recently show that CCN3 is a counter-regulatory molecule for the pro-fibrotic protein CCN2, and a potentially novel fibrosis therapy. The goal of this study was to assess the role of CCN3 in fibroproliferative/fibrotic responses in human dermal fibroblasts exposed to Omniscan, one of the gadolinium-based contrast agents associated with development of nephrogenic systemic fibrosis (NSF) a rare but life-threatening disease thought to be complication of NMR diagnostics in renal impaired patients. Human dermal fibroblasts were exposed to Omniscan; or to platelet-derived growth factor (PDGF) and transforming growth factor-β (TGF-β) as controls. Proliferation was assessed along with matrix metalloproteinase-1, tissue inhibitor of metalloproteinases-1 and type 1 procollagen in the absence and presence of CCN3. In parallel, CCN3 production was assessed in control and Omniscan-treated cells. The results showed that PDGF stimulated fibroblast proliferation, production of Timp-1 and MMP-1 whereas exogenous CCN3 inhibited, in a dose response manner, cell proliferation (approx. 50 % max.) and production of MMP-1 (approx 35 % max.) but had little effect on TIMP-1. TGF-β stimulated type 1 procollagen production but not proliferation, Timp-1 or MMP-1 compared to non-TGF-ß treated control cells, and CCN3 treatment blocked (approx. 80 % max.) this up-regulation. Interestingly, untreated, control fibroblasts produced high constitutive levels of CCN3 and concentrations of Omniscan that induced fibroproliferative/fibrogenic changes in dermal fibroblasts correspondingly suppressed CCN3 production. The use of PDGF and TGF-β as positive controls, and the study of differential responses, including that to Omniscan itself, provide the first evidence for a role of fibroblast-derived CCN3 as an endogenous regulator of pro-fibrotic changes, elucidating possible mechanism(s). In conclusion, these data support our hypothesis of a role for fibroblast-derived CCN3 as an endogenous regulator of pro-fibrotic changes in these cells, and suggest that CCN3 may be an important regulatory molecule in NSF and a target for treatment in this and other fibrotic diseases.

Gadolinium compounds signaling through TLR4 and TLR7 in normal human macrophages: establishment of a proinflammatory phenotype and implications for the pathogenesis of nephrogenic systemic fibrosis

Nephrogenic systemic sibrosis is a progressive disorder occurring in some renal insufficiency patients exposed to gadolinium-based contrast agents (GdBCA). Previous studies demonstrated that the GdBCA Omniscan upregulated several innate immunity pathways in normal differentiated human macrophages, induced rapid nuclear localization of the transcription factor NF-κB, and increased the expression and production of numerous profibrotic/proinflammatory cytokines, chemokines, and growth factors. To further examine GdBCA stimulation of the innate immune system, cultured human embryonic kidney 293 cells expressing one of seven different human TLRs or one of two human nucleotide-binding oligomerization domain-like receptors were exposed in vitro for 24 h to various GdBCA. The signaling activity of each compound was evaluated by its ability to activate an NF-κB-inducible reporter gene. Omniscan and gadodiamide induced strong TLR4- and TLR7-mediated reporter gene activation. The other Gd compounds examined failed to induce reporter gene activation. TLR pathway inhibition using chloroquine or an inhibitor of IL-1R-associated kinases 1 and 4 in normal differentiated human macrophages abrogated Omniscan-induced gene expression. Omniscan and gadodiamide signaling via TLRs 4 and 7 resulted in increased production and expression of numerous proinflammatory/profibrotic cytokines, chemokines, and growth factors, including CXCL10, CCL2, CCL8, CXCL12, IL-4, IL-6, TGF-β, and vascular endothelial growth factor. These observations suggest that TLR activation by environmental stimuli may participate in the pathogenesis of nephrogenic systemic fibrosis and of other fibrotic disorders including systemic sclerosis.

Stimulation of fibroblast proliferation by insoluble gadolinium salts

The purpose of this study was to assess insoluble salts containing gadolinium (Gd(3+)) for effects on human dermal fibroblasts. Responses to insoluble Gd(3+) salts were compared to responses seen with Gd(3+) solubilized with organic chelators, as in the Gd(3+)-based contrast agents (GBCAs) used for magnetic resonance imaging. Insoluble particles of either Gd(3+) phosphate or Gd(3+) carbonate rapidly attached to the fibroblast cell surface and stimulated proliferation. Growth was observed at Gd(3+) concentrations between 12.5 and 125 μM, with toxicity at higher concentrations. Such a narrow window did not characterize GBCA stimulation. Proliferation induced by insoluble Gd(3+) salts was inhibited in the presence of antagonists of mitogen-activated protein kinase and phosphatidylinositol 3-kinase signaling pathways (similar to chelated Gd(3+)) but was not blocked by an antibody to the platelet-derived growth factor receptor (different from chelated Gd(3+)). Finally, high concentrations of the insoluble Gd(3+) salts failed to prevent fibroblast lysis under low-Ca(2+) conditions, while similar concentrations of chelated Gd(3+) were effective. In conclusion, while insoluble Gd(3+) salts are capable of stimulating fibroblast proliferation, one should be cautious in assuming that GBCA dechelation must occur in vivo to produce the profibrotic changes seen in association with GBCA exposure in the subset of renal failure patients that develop nephrogenic systemic fibrosis.

Fibroblast response to lanthanoid metal ion stimulation: potential contribution to fibrotic tissue injury

The purpose of this study was to compare each of the 14 naturally occurring lanthanoid metal ions for ability to stimulate pro-fibrotic responses in human dermal fibroblasts. When fibroblasts were exposed to individual lanthanoids over the concentration range of 1-100 μM, increased proliferation was observed with each of the agents as compared with control cells that were already proliferating rapidly in a growth factor-enriched culture medium. Dose-response differences were observed among the individual metal ions. Matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 levels were also increased in response to lanthanoid exposure but type I procollagen production was not. A dose-response relationship between induction of proliferation and increased MMP-1 was observed. Non-lanthanoid transition metal ions (aluminum, copper, cobalt, iron, magnesium, manganese, nickel, and zinc) were examined in the same assays; there was little stimulation with any of these metals. When epidermal keratinocytes were examined in place of dermal fibroblasts, there was no growth stimulation with any of the lanthanoids. Several of the lanthanoid metals inhibited keratinocyte proliferation at higher concentrations (50-100 μM).

Fibroblast response to gadolinium: role for platelet-derived growth factor receptor

OBJECTIVE

The purpose of this study was to assess the effects of gadolinium (Gd3+), provided as gadolinium chloride, on fibroblast function.

MATERIALS AND METHODS

Human dermal fibroblasts in monolayer culture and intact skin in organ culture were exposed to the lanthanide metal (1-20 μM).

RESULTS

Increased proliferation was observed, in association with upregulation of matrix metalloproteinase-1 and tissue inhibitor of metalloproteinases-1, without an apparent increase in production of type I procollagen. A platelet-derived growth factor (PDGF) receptor-blocking antibody inhibited fibroblast proliferation in response to Gd3+ as did inhibitors of signaling pathways--that is, mitogen-activated protein kinase and phosphatidylinositol-3 kinase pathways--that are activated by PDGF.

CONCLUSION

The responses to gadolinium chloride are similar to responses previously seen with chelated Gd3+ in clinically used magnetic resonance imaging contrast agents. Fibroblast responses appear to reflect Gd3+-induced PDGF receptor activation and downstream signaling. Increased dermal fibroblast proliferation in conjunction with effects on matrix metalloproteinase-1 and tissue inhibitor of metalloproteinases-1 could contribute to the fibroplastic/fibrotic changes seen in the lesional skin of individuals with nephrogenic systemic fibrosis.

Advances in diagnostic radiology

Recent advances in diagnostic radiology are discussed on the basis of current publications in Investigative Radiology. Publications in the journal during 2009 and 2010 are reviewed, evaluating developments by modality and anatomic region. Technological advances continue to play a major role in the evolution and clinical practice of diagnostic radiology, and as such constitute a major publication focus. In the past 2 years, this includes advances in both magnetic resonance and computed tomography (in particular, the advent of dual energy computed tomography). An additional major focus of publications concerns contrast media, and in particular continuing research involving nephrogenic systemic fibrosis, its etiology, and differentiation of the gadolinium chelates on the basis of in vivo stability.

Evaluation of a fibrin-binding gadolinium chelate peptide tetramer in a brain glioma model

PURPOSE

To compare a fibrin-targeted, high relaxivity gadolinium tetramer, EP-2104R, in terms of magnitude of contrast enhancement (CE) and temporal time course, to a conventional extracellular gadolinium chelate, in a brain glioma model at 1.5-T magnetic resonance imaging.

METHODS

Six rats were evaluated, with each animal receiving (for separate studies) 0.05 mmol/kg gadopentetate dimeglumine (Gd DTPA or Magnevist) and 0.0125 mmol/kg of EP-2104R, with the 2 magnetic resonance examinations separated in each animal by 24 hours. The compound (EP-2104R) was synthesized using published methodology, being comprised of an 11 amino acid peptide derivatized at both the C- and N-termini with Gd-DOTA-like (Dotarem-like) moieties. T1-weighted scans were acquired precontrast and for 5 consecutive 2-minute intervals postcontrast, and subsequently at 15 and 20 minutes postcontrast.

RESULTS

Maximum tumor contrast-to-noise and CE both occurred at 1 minute versus at 5 minutes following administration of Gd DTPA versus EP-2104R, respectively. Utilizing an equivalent dose on a Gd ion per body weight basis, signal-to-noise, contrast-to-noise, and CE were greater for EP-2104R at all time points postcontrast, yielding overall statistically significantly greater levels of all 3 parameters with the latter. With EP-2104R, improvements in CE ranged between 87% and 391%, increasing at each measured time postcontrast with the exception of a slight decrease from 15 to 20 minutes postadministration. Histopathology confirmed, using immunofluorescence technique, abnormally increased fibrin within the tumor.

CONCLUSIONS

Statistically significantly greater brain tumor enhancement was noted with greater lesion enhancement at all observed time points postcontrast for EP-2104R utilizing an equivalent concentration to Gd DTPA on a per gadolinium ion basis. These findings together with the prolonged time course of enhancement suggest possible fibrin-binding and altered distribution kinetics.

Impact of contrast enhanced MRI on lymphocyte DNA damage and serum visfatin level

OBJECTIVES

Nephrogenic systemic fibrosis is a novel clinical entity encountered in subjects undergoing contrast enhanced magnetic resonance imaging (MRI). The aim of the present study is to evaluate the impact of contrast enhanced MRI exposure on lymphocyte DNA damage and serum levels of visfatin.

DESIGN AND METHODS

Twenty-eight subjects undergoing contrast enhanced hypophysial MRI with omniscan were included in the study. Blood samples were drawn before MRI, after non-contrast MRI and after contrast enhanced MRI from each subject. Lymphocyte DNA damage was analyzed by the alkaline comet assay, whereas serum visfatin level was assessed with enzyme immuno assay.

RESULTS

Both lymphocyte DNA damage and serum visfatin levels were statistically significantly increased in samples withdrawn after contrast enhanced MRI compared to samples withdrawn after non-contrast enhanced MRI and baseline samples (ANOVA p<0.001, for both).

CONCLUSIONS

Findings of the present study revealed that the contrast enhanced MRI is associated with increased lymphocyte DNA damage and increased serum visfatin level.

Clinical, biological, and skin histopathologic effects of ionic macrocyclic and nonionic linear gadolinium chelates in a rat model of nephrogenic systemic fibrosis

OBJECTIVE

the purpose of this study was to compare the clinical, pathologic, and biochemical effects of repeated administrations of ionic macrocyclic or nonionic linear gadolinium chelates (GC) in rats with impaired renal function.

MATERIAL AND METHODS

rats submitted to subtotal nephrectomy were allocated to single injections of 2.5 mmol/kg of gadodiamide (nonionic linear chelate), nonformulated gadodiamide (ie, without the free ligand caldiamide), gadoterate (ionic macrocyclic chelate), or saline for 5 consecutive days. Blinded semi-quantitative histopathologic and immunohistochemical examinations of the skin were performed, as well as clinical, hematological, and biochemical follow-up. Rats were killed at day 11. Long-term (up to day 32) follow-up of rats was also performed in an auxiliary study.

RESULTS

epidermal lesions (ulcerations and scabs) were found in 4 of the 10 rats treated with nonformulated gadodiamide. Two rats survived the study period. Inflammatory signs were observed in this group. No clinical, hematological, or biochemical signs were observed in the saline and gadoterate- or gadodiamide-treated groups. Plasma fibroblast growth factor-23 levels were significantly higher in the gadodiamide group than in the gadoterate group (day 11). Decreased plasma transferrin-bound iron levels were measured in the nonformulated gadodiamide group. Histologic lesions were in the range: nonformulated gadodiamide (superficial epidermal lesions, inflammation, necrosis, and increased cellularity in papillary dermis) > gadodiamide (small superficial epidermal lesions and signs of degradation of collagen fibers in the dermis) > gadoterate (very few pathologic lesions, similar to control rats).

CONCLUSIONS

repeated administration of the nonionic linear GC gadodiamide to renally impaired rats is associated with more severe histologic lesions and higher FGF-23 plasma levels than the macrocyclic GC gadoterate.

Effects of magnetic resonance imaging contrast agents on human umbilical vein endothelial cells and evaluation of magnetic resonance imaging contrast media-triggered transforming growth factor-beta induction in dermal fibroblasts (HSF) as a model for nephrogenic systemic fibrosis

RATIONALE AND OBJECTIVES

The objective of this study was to evaluate effects of 6 commercially available magnetic resonance contrast media (CM) on human umbilical vein endothelial cells (HUVEC) and the induction of transforming growth factor-beta (TGF-β) in dermal fibroblasts (HSF) as a possible model for the pathogenesis of nephrogenic systemic fibrosis.

METHODS

HUVECs were incubated with 10× and 20× of the molar standard blood concentration achieved with CM applications for magnetic resonance imaging examinations (10× and 20× concentration) for 24 hours using gadolinium-based CM Gadovist, Magnevist, Multihance, and Omniscan, as well as Teslascan (Manganese-based), and Resovist (Iron-based). Proliferation kinetics (PK), colony formation, and viability assays were performed. Additionally, human dermal fibroblasts (HSF) were incubated for 24 hours with 1× and 20× concentration in all 6 CM, and TGF-β levels were assessed directly after the incubation period as well as on days 3 and 8 postincubation.

RESULTS

HUVEC PK data show similar gains in cell numbers for all 6 CM in both concentration groups over the 17-day assessment period. Only cells incubated with Omniscan and Teslascan differed from the other groups on days 3 and 7 postincubation (P < 0.05). After day 7, a cell regain occurred in the Omniscan and Teslascan groups reaching the numbers of the other groups in sequel. Differences in colony formation were consistent with PK results with a statistically significant reduction in clonogenic activity for Teslascan and Omniscan in HUVEC cells, P < 0.05. No reduction in viability was seen for all groups and conditions. TGF-β expression of HSF cells incubated with 1× concentration and all CM did not differ significantly from control cells for any point in time investigated. At 20× concentration directly after incubation, TGF-β was significantly reduced for the Teslascan and Resovist group as 3 compared with control and all other CM groups, P < 0.05. On day 3 postincubation, only Resovist-incubated HSF cells showed a significant reduction of TGF-β (1.614, standard deviations: 89) as compared with the control group (2.883, standard deviations: 30) and the other CM. TGF-β was slightly reduced for all CM groups 8 days after incubation (not statistically significant, P > 0.05).

CONCLUSIONS

After 24 hours of incubation with Omniscan and Teslascan (10× and 20× concentration), considerable short-term antiproliferative effects in HUVECs were observed. HSF cells (20× concentration) showed a reduction of TGF-β for Resovist and Teslascan directly after incubation, whereas TGF-β levels in HSF cells were slightly reduced for all CM 8 days after incubation. Therefore, TGF-β-mediated proliferative effects on fibroblasts or on collagen synthesis potentially leading to nephrogenic systemic fibrosis may mainly be triggered by tissue monocytes and macrophages in the peripheral blood instead of dermal fibroblasts.

Responses of human skin in organ culture and human skin fibroblasts to a gadolinium-based MRI contrast agent: comparison of skin from patients with end-stage renal disease and skin from healthy subjects

OBJECTIVE

Nephrogenic systemic fibrosis is a clinical syndrome occurring in a small subset of patients with end-stage renal disease (ESRD). Exposure to certain of the gadolinium-based contrast agents during magnetic resonance imaging appears to be a trigger. The pathogenesis of the disease is largely unknown. The present study addresses potential pathophysiologic mechanisms.

MATERIALS AND METHODS

We have compared responses in organ-cultured skin and skin fibroblasts from individuals with ESRD to responses of healthy control subjects to Omniscan treatment.

RESULTS

Treatment of skin from ESRD patients with Omniscan stimulated production of matrix metalloproteinase-1 and tissue inhibitor of metalloproteinases-1, but not type I procollagen. The same treatment also stimulated an increase in hyaluronan production. Similar results were seen with skin from normal controls but basal levels were higher in ESRD patients. Fibroblasts in monolayer culture gave the same responses, but there were no differences based on whether the cells were isolated from the skin of healthy subjects or those with ESRD.

CONCLUSION

These data indicate that Omniscan exposure alters an enzyme/inhibitor system responsible for regulating collagen turnover in the skin and directly stimulates hyaluronan production. The higher basal levels of type I procollagen, matrix metalloproteinase-1, tissue inhibitor of metalloproteinases-1, and hyaluronan in the skin from ESRD patients could contribute to the sensitivity of this patient population to fibrotic changes, which might be induced by exposure to some of the gadolinium-based contrast agents.

Collagenolytic activity is suppressed in organ-cultured human skin exposed to a gadolinium-based MRI contrast agent

OBJECTIVE

Human skin produces increased amounts of matrix metalloproteinase-1 (MMP-1) when exposed in organ culture to Omniscan, one of the gadolinium-based MRI contrast agents (GBCA). MMP-1, by virtue of its ability to degrade structural collagen, contributes to collagen turnover in the skin. The objective of the present study was to determine whether collagenolytic activity was concomitantly up-regulated with increased enzyme.

MATERIALS AND METHODS

Skin biopsies from normal volunteers were exposed in organ culture to Omniscan. Organ culture fluids obtained from control and treated skin were examined for ability to degrade type I collagen. The same culture fluids were examined for levels of MMP-1, tissue inhibitor of metalloproteinases-1 (TIMP-1), and complexes of MMP-1 and TIMP-1.

RESULTS

Although MMP-1 was increased in culture fluid from Omniscan-treated skin, there was no increase in collagenolytic activity. In fact, collagenolytic activity declined. Increased production of TIMP-1 was also observed in Omniscan-treated skin, and the absolute amount of TIMP-1 was greater than the amount of MMP-1. Virtually all of the MMP-1 was present in MMP-1-TIMP-1 complexes, but the majority of TIMP-1 was not associated with MMP-1. When human dermal fibroblasts were exposed to TIMP-1 (up to 250 ng/mL), no increase in proliferation was observed, but an increase in collagen deposition into the cell layer was seen.

CONCLUSION

Gadolinium-based MRI contrast agent exposure has recently been linked to a fibrotic skin condition in patients with impaired kidney function. The mechanism is unknown. The increase in TIMP-1 production and concomitant reduction in collagenolytic activity demonstrated here could result in decreased collagen turnover and increased deposition of collagen in lesional skin.

Mechanism of NSF: New evidence challenging the prevailing theory

Nephrogenic systemic fibrosis (NSF) has been associated with the administration of gadolinium-based contrast agents in patients with severely impaired renal function (SIRF), endstage renal disease (ESRD), or acute renal failure (ARF). Since the vast majority of these patients do not get NSF, it is highly likely that patient factors play a role in its development. Although "free" or dechelated gadolinium is thought by some to be the only trigger of NSF, recent evidence suggests that chelated gadolinium may be important. Chelated gadolinium such as Omniscan (gadodiamide) and Magnevist (gadopentetate) can directly stimulate macrophages and monocytes in vitro to release profibrotic cytokines and growth factors capable of initiating and supporting the tissue fibrosis that is characteristic of NSF. In addition, an effect of chelated gadolinium on fibroblasts has also been demonstrated. Chelated gadolinium in the form of Omniscan, Magnevist, MultiHance, and ProHance increased proliferation of human dermal fibroblasts. Indeed, increased numbers of macrophages, together with activated fibroblasts and fibrocytes, are essential cells in the fibrotic process and are present in NSF skin. Accordingly, it is important that chelated gadolinium, in combination with patient cofactors, is considered in the etiology of NSF associated with enhanced scans. J. Magn. Reson. Imaging 2009;30:1277-1283. (c) 2009 Wiley-Liss, Inc.