Induction of the expression of profibrotic cytokines and growth factors in normal human peripheral blood monocytes by gadolinium contrast agents

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.

Dermatological Manifestations in Patients With Chronic Kidney Disease: A Review

Chronic kidney disease (CKD) is a progressive disease and has multiple clinical manifestations; when CKD reaches the end stage, at least one cutaneous manifestation appears due to some increased toxin levels or a constant proinflammatory state. Nonspecific manifestations include pruritus, xerosis, pigmentation disorders, acquired ichthyosis, purpuric spots, and nail disorders. Some specific manifestations are bullous dermatoses, acquired perforating dermatoses (APD), eruptive xanthoma, access site infections, calcifying disorders, and nephrogenic systemic fibrosis (NSF). All these cutaneous changes negatively impact patients; early recognition and diagnosis of these dermatoses will make a difference in their quality of treatment. Exploring a patient's skin is fundamental to suspect some diseases and increased toxin levels; pruritus occurs when uremic toxins are raised, and nail disorders are associated with hypoalbuminemia. This review provides the clinician with information on the clinical manifestations that occur in CKD, including epidemiology, pathophysiology, clinical manifestations, diagnosis, histopathology, treatment, and life impact of the dermatoses in CKD.

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.

Dynamic Serial Cytokine Measurements During Intravenous Ca-DTPA Chelation in Gadolinium Deposition Disease and Gadolinium Storage Condition: A Pilot Study

PURPOSE

The aim of this study was to investigate the feasibility of measuring early changes in serum cytokine levels after intravenous diethylenetriaminepentaacetic acid (Ca-DTPA) chelation in patients manifesting either gadolinium deposition disease (GDD) or gadolinium storage condition (GSC) and the possible usefulness of this method in further research.

METHODS

Four patients with recent-onset GDD (≤1 year) and 2 patients with long-standing GSC (4 and 9 years) underwent chelation with intravenous bolus administration of Ca-DTPA. Multiple blood draws were performed to measure serum cytokines: at T = 0 (before Ca-DTPA injection) and 1, 5, 10, 30, 60 minutes, and 24 hours after Ca-DTPA injection. Patients rated the severity of GDD symptom flare at 24 hours. The 24-hour urine Gd amounts were measured prechelation and for the 24 hours after chelation. Serum samples were analyzed blind to whether patients had GDD or GSC but with knowledge of the time points characterizing each sample.

RESULTS

Urine samples for both GDD and GSC patients showed increases in Gd postchelation. All GDD patients experienced flare reactions postchelation; the 2 GSC patients did not. Two cytokines, EGF and sCD40L, peaked at 30 minutes postchelation in at least 4 of the 6 participants. Three cytokines, ENA78/CXCL5, EOTAXIN/CCL11, and LEPTIN, peaked at 24 hours in at least 4 of the 6 participants. Two participants were high outliers for a large number of cytokines across time points. No clear distinction between GDD and GSC was apparent from the cytokine patterns, although differences were present.

CONCLUSIONS

This pilot study describes precise temporal resolution (in the range of minutes) after a cytokine-inciting event. Select cytokines exhibited peak values at different time points. At this preliminary stage of investigation, peak cytokine release seems to reflect the amount of Gd mobilized rather than the severity of the patient symptomatic reaction. Too few subjects were studied to support statistical analysis between GDD and GSC groups, although differences were observed through visual data analysis.

Real-Time Deformability Cytometry Detects Leukocyte Stiffening After Gadolinium-Based Contrast Agent Exposure

OBJECTIVES

Reports on gadolinium (Gd) retention in soft tissues after administration of Gd-based contrast agents (GBCAs) raise concerns about Gd-induced changes in the biophysical properties of cells and tissues. Here, we investigate if clinical GBCAs of both classes of linear and macrocyclic structure cause changes in the mechanical properties of leukocytes in human blood samples.

MATERIAL AND METHODS

Real-time deformability cytometry was applied to human blood samples from 6 donors. The samples were treated with 1 mM gadoteric acid (Dotarem), gadopentetic acid (Magnevist), gadobutrol (Gadovist), or Gd trichloride at 37°C for 1 hour to mimic clinical doses of GBCAs and exposure times. Leukocyte subtypes-lymphocytes, monocytes, and neutrophils-were identified based on their size and brightness and analyzed for deformability, which is inversely correlated with cellular stiffness.

RESULTS

We observed significant stiffening (3%-13%, P < 0.01) of all investigated leukocyte subtypes, which was most pronounced for lymphocytes, followed by neutrophils and monocytes, and the effects were independent of the charge and steric structure of the GBCA applied. In contrast, no changes in cell size and brightness were observed, suggesting that deformability and cell stiffness measured by real-time deformability cytometry are sensitive to changes in the physical phenotypes of leukocytes after GBCA exposure.

CONCLUSIONS

Real-time deformability cytometry might provide a quantitative blood marker for critical changes in the physical properties of blood cells in patients undergoing GBCA-enhanced magnetic resonance imaging.

Gadolinium Tissue Distribution in a Large-Animal Model after a Single Dose of Gadolinium-based Contrast Agents

Background There is an ongoing scientific debate about the degree and clinical importance of gadolinium deposition in the brain and other organs after administration of gadolinium-based contrast agents (GBCAs). While most published data focus on gadolinium deposition in the brain, other organs are rarely investigated. Purpose To compare gadolinium tissue concentrations in various organs 10 weeks after one injection (comparable to a clinically applied dose) of linear and macrocyclic GBCAs in a large-animal model. Materials and Methods In this prospective animal study conducted from March to May 2018, 36 female Swiss-Alpine sheep (age range, 4-10 years) received one injection (0.1 mmol/kg) of macrocyclic GBCAs (gadobutrol, gadoteridol, and gadoterate meglumine), linear GBCAs (gadodiamide and gadobenate dimeglumine), or saline. Ten weeks after injection, sheep were sacrificed and tissues were harvested. Gadolinium concentrations were quantified with inductively coupled plasma mass spectrometry (ICP-MS). Histologic staining was performed. Data were analyzed with nonparametric tests. Results At 10 weeks after injection, linear GBCAs resulted in highest mean gadolinium concentrations in the kidney (502 ng/g [95% CI: 270, 734]) and liver (445 ng/g [95% CI: 202, 687]), while low concentrations were found in the deep cerebellar nuclei (DCN) (30 ng/g [95% CI: 20, 41]). Tissue concentrations of linear GBCAs were three to 21 times higher compared with those of macrocyclic GBCAs. Administered macrocyclic GBCAs resulted in mean gadolinium concentrations of 86 ng/g (95% CI: 31, 141) (P = .08) in the kidney, 21 ng/g (95% CI: 4, 39) (P = .15) in liver tissue, and 10 ng/g (95% CI: 9, 12) (P > .99) in the DCN, which were not significantly elevated when compared with concentrations in control animals. No histopathologic alterations were observed irrespective of tissue concentrations within any examined organ. Conclusion Ten weeks after one injection of a clinically relevant dose of gadolinium-based contrast agents, the liver and kidney appeared to be reservoirs of gadolinium; however, despite gadolinium presence, no tissue injury was detected. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Clément in this issue.

Heat-Killed and Live Enterococcus faecalis Attenuates Enlarged Prostate in an Animal Model of Benign Prostatic Hyperplasia

In the present study, we investigated the inhibitory effect of heat-killed Enterococcus faecalis (E. faecalis) and live E. faecalis on benign prostatic hyperplasia (BPH). The BPH rat model was established by administering male rats with testosterone propionate (TP, 5 mg/kg, in corn oil) via subcutaneous injections daily for four weeks after castration. The rats were divided into five groups: Con, corn oil-injected (s.c.) + DW administration; BPH, TP (5 mg/kg, s.c.) + DW administration; BPH+K_EF, TP (5 mg/kg, s.c.) + heat-killed E. faecalis (7.5 × 10¹² CFU/g, 2.21 mg/kg) administration; BPH+L_EF, TP (5 mg/kg, s.c.) + live E. faecalis (1 × 10¹¹ CFU/g, 166 mg/kg) administration; BPH+Fi, TP (5 mg/kg, s.c.) + finasteride (1 mg/kg) administration. In both of BPH+K_EF and BPH+L_EF groups, the prostate weight decreased and histological changes due to TP treatment recovered to the level of the Con group. Both of these groups also showed regulation of androgen-signaling factors, growth factors, and apoptosis-related factors in prostate tissue. E. faecalis exhibited an inhibitory effect on benign prostatic hyperplasia, and even heat-killed E. faecalis showed similar efficacy on the live cells in the BPH rat model. As the first investigation into the effect of heat-killed and live E. faecalis on BPH, our study suggests that heat-killed E. faecalis might be a food additive candidate for use in various foods, regardless of heat processing.

Acute Chelation Therapy-Associated Changes in Urine Gadolinium, Self-reported Flare Severity, and Serum Cytokines in Gadolinium Deposition Disease

OBJECTIVES

The aim of this study was to determine the following in patients who have undergone magnetic resonance imaging with gadolinium-based contrast agents (GBCAs) and meet the proposed diagnostic criteria for gadolinium deposition disease (GDD): (1) the effectiveness of chelation therapy (CT) with intravenous Ca-diethylenetriaminepentaacetic acid in removing retained gadolinium (Gd) and factors affecting the amount removed; (2) the frequency of CT-induced Flare, that is, GDD diagnostic symptom worsening, and factors affecting Flare intensity; (3) whether, as reported in a separate cohort, GDD patients' serum cytokine levels differ significantly from those in healthy normal controls and change significantly in response to CT; and (4) whether urine Gd, Flare reaction, and serum cytokine findings in GDD patients are mimicked in non-ill patients described as having gadolinium storage condition (GSC).

MATERIALS AND METHODS

Twenty-one GDD subjects and 3 GSC subjects underwent CT. Patients provided pre-CT and post-CT 24-hour urine samples for Gd content determination along with pre-CT and 24-hour post-CT serum samples for cytokine analysis. Patients rated potential Flare 24 hours after CT. Pre-CT and post-CT 24-hour urine Gd analyses and Luminex serum cytokine assays were performed blind to patients' GDD and GSC status and all other data except age and sex. Serum cytokine levels in a healthy normal control group of age- and sex-matched subjects drawn from Stanford influenza vaccination studies were measured once, contemporaneously with those of GDD and GSC patients, using the same Luminex assay.

RESULTS

Urine Gd amounts increased post-CT by 4 times or more after 87% of the 30 CT sessions. The most important factors appeared to be the time since the last GBCA dose and the cumulative dose received. Urine Gd amounts for GDD and GSC patients fell in the same ranges. All GDD patients, and no GSC patient, reported a Flare 24 hours post-CT. Linear regression found that Flare intensity was significantly predicted by a model including pre- and post-CT Gd amounts and the number of GBCA-enhanced magnetic resonance imaging. Post-CT, multiple cytokines showed strong positive relationships with GDD patients' Flare intensity in multivariable models. The pre-CT serum levels of 12 cytokines were significantly different in GDD patients compared with healthy flu vaccine controls. The small number of GSC patients precluded analogous statistical testing. Post-CT, GDD patients' serum levels of 20 cytokines were significantly decreased, and 2 cytokines significantly increased. These cytokines did not exhibit the same change pattern in the 3 GSC patients. The small number of GSC patients precluded statistical comparisons of GSC to GDD patients' results.

CONCLUSIONS

In this preliminary study, 24-hour urine Gd content increased markedly and similarly in GDD and GSC patients after Ca-diethylenetriaminepentaacetic acid CT. Post-CT Flare reaction developed only in GDD patients. The current study is the second finding significantly different serum cytokine levels in GDD patients compared with healthy normal controls. These differences and the difference between GDD and GSC patients' Flare and cytokine responses to CT suggest some inflammatory, immunologic, or other physiological differences in patients with GDD. Further research into the treatment and physiological underpinnings of GDD is warranted.

Chemical exposure-induced systemic fibrosing disorders: Novel insights into systemic sclerosis etiology and pathogenesis

Numerous drugs and chemical substances are capable of inducing exaggerated tissue fibrotic responses. The vast majority of these agents cause localized fibrotic tissue reactions or fibrosis confined to specific organs. Although much less frequent, chemically-induced systemic fibrotic disorders have been described, sometimes occurring as temporally confined outbreaks. These include the Toxic Oil Syndrome (TOS), the Eosinophilia-Myalgia Syndrome (EMS), and Nephrogenic Systemic Fibrosis (NSF). Although each of these disorders displays some unique characteristics, they all share crucial features with Systemic Sclerosis (SSc), the prototypic idiopathic systemic fibrotic disease, including vasculopathy, chronic inflammatory cell infiltration of affected tissues, and cutaneous and visceral tissue fibrosis. The study of the mechanisms and molecular alterations involved in the development of the chemically-induced systemic fibrotic disorders has provided valuable clues that may allow elucidation of SSc etiology and pathogenesis. Here, we review relevant aspects of the TOS, EMS, and NSF epidemic outbreaks of chemically-induced systemic fibrosing disorders that provide strong support to the hypothesis that SSc is caused by a toxic or biological agent that following its internalization by endothelial cells induces in genetically predisposed individuals a series of molecular alterations that result in the development of SSc clinical and pathological alterations.

An initial investigation of serum cytokine levels in patients with gadolinium retention

Objective

To determine whether individuals with proposed gadolinium deposition disease (GDD) have elevated serum levels of pro-inflammatory and pro-fibrotic cytokines, and whether specific cytokines are correlated with certain symptoms.

Materials and Methods

Twenty-four participants recruited between May 2016 and June 2017 met GDD diagnostic criteria. The 64 control subjects provided serum samples before prophylactic flu vaccination. Serum cytokine levels were obtained with Luminex serum cytokine assay using eBiosciences/Affymetrix human 62-plex kits. Wilcoxon rank-sum tests were performed to assess the difference between the median fluorescence intensity values for the participants and the control group. Generalized linear models were built to evaluate the association between each cytokine of interest and selected participant symptoms.

Results

Serum levels of 14 cytokines, including nine pro-inflammatory cytokines, were statistically significantly elevated compared to controls (p ≤ 0.05). Hypotheses regarding pro-fibrotic cytokines and cytokine links to specific symptoms' intensity were not confirmed.

Conclusion

The statistically significantly elevated cytokines may be markers of susceptibility to GDD or agents of symptom induction. These findings suggest that individuals developing symptoms characteristic of GDD after a contrast-assisted magnetic resonance imaging should be studied to investigate whether gadolinium retention and elevated cytokines may be related to their symptoms.

The gadolinium hypothesis for fibromyalgia and unexplained widespread chronic pain

Fibromyalgia (FM) is a chronic, painful, heterogeneous, and common disorder carrying a substantial socio-economical burden. It lacks effective cures and its aetiology is still unknown. There exists evidence for central and peripheral neurological contribution to the symptoms but grasping the real source of abnormal nervous system sensitization remains an ongoing challenge. There exists an association between an injury/trauma and the onset of the symptoms, but a causal relationship has not been yet sufficiently supported by scientific evidence. I postulate a role for gadolinium-based contrast agents and retention of gadolinium in the body. This conjecture breaks the hypothesis of a direct role for a physical injury/trauma per se in favour of an indirect one by the subsequent diagnostic procedures. It creates a new link between retention of gadolinium in the body and painful conditions as FM and unexplained chronic widespread pain reported after a trauma, surgery, or medical illness. Experimental evidence demonstrates possible retention of gadolinium species in human body, still lacking conclusive answers on their pathological consequences. Notwithstanding, there exist some initial data that report unexplained chronic widespread pain and symptoms of FM in those patients: they are suggestive for pathological consequences associated with gadolinium retention. Besides clear compelling symptoms overlapping, biochemical findings are provided to sustain the hypothesis of a role for gadolinium in the disease process focusing on neurotransmitters, endogenous metal cations, cytokines, and muscle tissue. Experimental findings strongly support the hypothesis of impairment at the cellular, intracellular, and systemic levels in FM. And these data are highly compatible with collateral effects associated with the interference of the gadolinium ion and its pharmaceutical chelates into biochemical pathways in vivo. The hypothesis presented in this article, along with the support of scientific evidence, links FM and unexplained chronic widespread pain reported after a trauma, surgery, or medical illness to retention of gadolinium in the body. If the hypothesis is confirmed, it could improve diagnosis and prevention, while providing a ground for development of new treatments.

Safety of Gadolinium Administration in Children

The introduction of paramagnetic contrast in the late 1980s constituted a paradigm shift boosting the efficacy of magnetic resonance imaging. Due to its high magnetic moment, gadolinium-based contrast agent made its way smoothly as the flagship paramagnetic contrast. With the widespread application, reports of untoward effects started to surface. Allergic reactions, nephrogenic systemic sclerosis, and deposition in brain tissue dented the safety profile of gadolinium-based contrast agent. Better understanding of these adverse effects prompted preventive measures. This article elucidates the gadolinium-based contrast agent toxicity in the pediatric population based on the current available evidence.

Nephrogenic Systemic Fibrosis in a Patient With Multiple Inflammatory Disorders

The risk of developing nephrogenic systemic fibrosis in patients with end stage renal disease may increase with exposure to gadolinium-based contrast dyes during magnetic resonance imaging.

Abrogation of transforming growth factor-β-induced tissue fibrosis in TBRIcaCol1a2Cre transgenic mice by the second generation tyrosine kinase inhibitor SKI-606 (Bosutinib)

Transforming growth factor-β (TGF-β) plays a crucial role in the pathogenesis of Systemic Sclerosis (SSc) and other fibrotic disorders. TGF-β-mediated c-Abl and Src kinase activation induces strong profibrotic cascade signaling. The purpose of this study was to test in vivo the antifibrotic activity of Bosutinib (SKI-606), a second generation c-Abl and Src kinase inhibitor, on TGF-β induced cutaneous and pulmonary fibrosis. For this purpose, we employed the TBRIcaCol1a2Cre transgenic mice expressing an inducible constitutively active TGF-β receptor 1 constitutively activated by Col1a promoter-mediated Cre recombinase. The mice were treated parenterally with 2.5, 5.0 or 10.0 mg/kg/day of Bosutinib for 42 days. Skin and lungs from control and Bosutinib-treated mice (n = 6 per group) were assessed by histopathology, measurement of tissue hydroxyproline content, PCR analysis of tissue fibrosis associated gene expression, and evidence of myofibroblast activation. Mice with constitutive TGF-β-1 signaling displayed severe cutaneous and pulmonary fibrosis. Bosutinib administration decreased collagen deposition and hydroxyproline content in the dermis and lungs in a dose-dependent manner. Bosutinib also reversed the marked increase in profibrotic and myofibroblast activation-associated gene expression. These results demonstrate that constitutive TGF-β-1-signaling-induced cutaneous and pulmonary fibrosis were abrogated in a dose-related manner following parenteral administration of the c-Abl and Src tyrosine kinase inhibitor, Bosutinib. These results indicate that Bosutinib may be a potential therapeutic agent for tissue fibrosis in SSc and other fibroproliferative disorders.

Endothelial cell-specific activation of transforming growth factor-β signaling in mice induces cutaneous, visceral, and microvascular fibrosis

In this study, we tested the hypothesis that constitutive endothelial cell-specific activation of TGF-β signaling induces tissue fibrosis and vasculopathy resembling the characteristic fibrotic and vascular alterations of systemic sclerosis. Transgenic mice with inducible expression of a constitutively active TGF-β receptor I specifically in endothelial cells were generated by intercrossing mice harboring a constitutively active TGF-β receptor I with a mouse strain containing the endothelial cell-specific Cdh5 gene promoter directing the tamoxifen-inducible expression of the Cre-ER^T2 cassette. Administration of tamoxifen to these mice would result in constitutive TGF-β activation and signaling confined to endothelial lineage cells. The effects of constitutive TGF-β endothelial cell activation were assessed by histopathological examination of skin and various internal organs, tissue hydroxyproline analysis, and assessment of expression of myofibroblast differentiation and TGF-β signaling genes employing real-time PCR and immunohistochemical staining of lung vessels for endothelial- and myofibroblast-specific proteins. Constitutive TGFβ-1 signaling in endothelial cells resulted in cutaneous and visceral fibrosis with prominent fibrotic involvement of the lungs and severe perivascular and subendothelial fibrosis of small arterioles. A marked increase in the expression of fibrosis-associated genes and of genes indicative of myofibroblast activation was also found. Confocal microscopy of lung vessels showed evidence consistent with the induction of endothelial-to-mesenchymal transition (EndoMT). Taken together, our data indicate that transgenic mice with constitutive endothelial cell-specific activation of TGF-β signaling display severe cutaneous, pulmonary, and microvascular fibrosis resembling the fibrotic and microvascular alterations characteristic of systemic sclerosis.

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.

Interleukin-12 inhibits the hepatocellular carcinoma growth by inducing macrophage polarization to the M1-like phenotype through downregulation of Stat-3

Hepatocellular carcinoma is the third most common cause of cancer death worldwide. Novel early detection biomarkers and efficacious therapy strategies are needed. Macrophages recruited from circulation monocytes are the major component of solid cancer and play an important role in the carcinogenesis. Whether overexpression of L-12 in monocytes could induce the phenotype directional differentiation into tumoricidal M1 macrophages and inhibit HCC growth in tumor microenvironment was investigated in this study. For the establishment of the monocyte/IL-12 and polarization of M1-like macrophage, the IL-12 overexpressing recombinant monocyte/IL-12 cells were established by infecting with pAd5F35-CMV/IL-12 adenovirus and co-cultured with HCC SMMC-7721 and Hep3B cells. It was found that the phenotype of monocyte/IL-12 polarized to M1-like macrophages with CD197high IL-12high CD206low IL-10low, and decreased expression of TGF-β, VEGF-A, and MMP-9. In order to explore the mechanism underlying the macrophages polarization, we detected the Stat-3 pathway and its downstream transcription factor c-myc, and found that the p-Stat-3 and c-myc were down-regulated. To evaluate the effects of monocyte/IL-12 on inhibiting HCC growth, various assays including CCK8, flow cytometry, colony-forming and Transwell assays in vitro, and xenograft mouse models and immunohistochemical analyses in vivo were used to detect the HCC growth and relative markers. Treated with IL-12 overexpressing monocytes, the xenograft tumor growth was significantly inhibited in vivo. These results have proven that IL-12-overexpressed monocytes could directionally differentiate to M1-like macrophages through downregulation of Stat-3 and result in the inhibition of HCC growth.

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.

The significance of macrophage polarization subtypes for animal models of tissue fibrosis and human fibrotic diseases

The systemic and organ-specific human fibrotic disorders collectively represent one of the most serious health problems world-wide causing a large proportion of the total world population mortality. The molecular pathways involved in their pathogenesis are complex and despite intensive investigations have not been fully elucidated. Whereas chronic inflammatory cell infiltration is universally present in fibrotic lesions, the central role of monocytes and macrophages as regulators of inflammation and fibrosis has only recently become apparent. However, the precise mechanisms involved in the contribution of monocytes/macrophages to the initiation, establishment, or progression of the fibrotic process remain largely unknown. Several monocyte and macrophage subpopulations have been identified, with certain phenotypes promoting inflammation whereas others display profibrotic effects. Given the unmet need for effective treatments for fibroproliferative diseases and the crucial regulatory role of monocyte/macrophage subpopulations in fibrogenesis, the development of therapeutic strategies that target specific monocyte/macrophage subpopulations has become increasingly attractive. We will provide here an overview of the current understanding of the role of monocyte/macrophage phenotype subpopulations in animal models of tissue fibrosis and in various systemic and organ-specific human fibrotic diseases. Furthermore, we will discuss recent approaches to the design of effective anti-fibrotic therapeutic interventions by targeting the phenotypic differences identified between the various monocyte and macrophage subpopulations.

Gadolinium-based compounds induce NLRP3-dependent IL-1β production and peritoneal inflammation

OBJECTIVE

Nephrogenic systemic fibrosis (NSF) is a progressive fibrosing disorder that may develop in patients with chronic kidney disease after administration of gadolinium (Gd)-based contrast agents (GBCAs). In the setting of impaired renal clearance of GBCAs, Gd deposits in various tissues and fibrosis subsequently develops. However, the precise mechanism by which fibrosis occurs in NSF is incompletely understood. Because other profibrotic agents, such as silica or asbestos, activate the nucleotide-binding oligomerisation domain (NOD)-like receptor protein 3 (NLRP3) inflammasome and initiate interleukin (IL)-1β release with the subsequent development of fibrosis, we evaluated the effects of GBCAs on inflammasome activation.

METHODS

Bone marrow derived macrophages from C57BL/6, Nlrp3(-/-) and Asc(-/-) mice were incubated with three Gd-containing compounds and IL-1β activation and secretion was detected by ELISA and western blot analysis. Inflammasome activation and regulation was investigated in IL-4- and interferon (IFN)γ-polarised macrophages by ELISA, quantitative real time (qRT)-PCR and NanoString nCounter analysis. Furthermore, C57BL/6 and Nlrp3(-/-)mice were intraperitoneally injected with GBCA and recruitment of inflammatory cells to the peritoneum was analysed by fluorescence-activated cell sorting (FACS).

RESULTS

Free Gd and GBCAs activate the NLRP3 inflammasome and induce IL-1β secretion in vitro. Gd-diethylenetriaminepentaacetic acid also induces the recruitment of neutrophils and inflammatory monocytes to the peritoneum in vivo. Gd activated IL-4-polarised macrophages more effectively than IFNγ-polarised macrophages, which preferentially expressed genes known to downregulate inflammasome activity.

CONCLUSIONS

These data suggest that Gd released from GBCAs triggers a NLRP3 inflammasome-dependent inflammatory response that leads to fibrosis in an appropriate clinical setting. The preferential activation of IL-4-differentiated macrophages is consistent with the predominantly fibrotic presentation of NSF.

Current status of nephrogenic systemic fibrosis

Nephrogenic systemic fibrosis (NSF) occurs in patients with advanced chronic kidney disease (CKD) or acute renal failure, most commonly following exposure to gadolinium-based contrast agents (GBCAs). NSF can be debilitating and associated with increased mortality. The putative association of NSF with GBCAs prompted the development of guidelines to limit the use of these contrast agents in at-risk patients. Indeed, the incidence of NSF has decreased dramatically following application of these guidelines, which appears to be the only effective means of decreasing NSF incidence. Thus, increasing clinician awareness of these updated guidelines is important. The present review introduces and compares updated guidelines for GBCA use and discusses the latest advances in the understanding of the pathogenic mechanisms and treatment of NSF.

Induction of a type I interferon signature in normal human monocytes by gadolinium-based contrast agents: comparison of linear and macrocyclic agents

The gadolinium-based contrast agent (GdBCA) Omniscan activates human macrophages through Toll-like receptor (TLR)-4 and TLR-7 signalling. To explore the mechanisms responsible we compared the ability of linear and macrocyclic GdBCA to induce a type I interferon signature and a proinflammatory/profibrotic phenotype in normal human monocytes in vitro. Expression of genes associated with type I interferon signalling and inflammation and production of their corresponding proteins were determined. Both linear and macrocyclic GdBCA stimulated expression of multiple type I interferon-regulated genes and the expression of numerous chemokines, cytokines and growth factors in normal human peripheral blood monocytes. There was no correlation between the magnitude of the measured response and the Gd chelate used. To explore the mechanisms responsible for GdBCA induction of fibrosis in nephrogenic systemic fibrosis (NSF) in vitro, normal human dermal fibroblasts were incubated with GdBCA-treated monocyte culture supernatants and the effects on profibrotic gene expression were examined. Supernatants from monocytes exposed to all GdBCA stimulated types I and III collagen, fibronectin and α-smooth muscle actin (α-SMA) expression in normal dermal fibroblasts. The results indicate that the monocyte activation induced by GdBCA may be the initial step in the development of GdBCA associated fibrosis in NSF.

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.

Expression of the calcium sensing receptor in human peripheral blood T lymphocyte and its contribution to cytokine secretion through MAPKs or NF-κB pathways

The calcium-sensing receptor (CaSR) has been reported to play an important role in many tissues and organs. However, studies about the expression and function of CaSR in T lymphocytes are still not very lucid. In this study, we investigated the above-mentioned issues using RT-PCR, immunofluorescence staining, Western blotting, and the ELISA techniques. We found that the CaSR protein was expressed, and mainly located in the membrane in the normal human peripheral blood T lymphocytes. GdCl(3) (an agonist of CaSR) increased the dose-dependency of the CaSR expression, which was abolished by NPS2390 (an inhibitor of CaSR). GdCl(3) and Ca(2+) increased the phosphorylation of extracellular signal-regulated kinase (ERK)1/2 (one subgroup of MAPKs) and P65 (subunit of NF-κB),but, they had no significant effects on the JNK and P38 subgroups of MAPKs. Meantime, GdCl(3) and Ca(2+) stimulated both the IL-6 and TNF-β releases and their mRNA expressions. However, these effects of GdCl(3) and Ca(2+) were inhibited by NPS2390, U0126 (MAPKs pathway inhibitor) or Bay-11-7082 (NF-κB pathway inhibitor). These results suggested that CaSR was functionally expressed in the T cells, and the activated CaSR contributed to the cytokine secretion through the partial MAPK and NF-κB pathways.

Gadolinium in pediatric cardiovascular magnetic resonance: what we know and how we practice

BACKGROUND

The association of gadolinium-based contrast agents (GBCAs) with nephrogenic systemic fibrosis (NSF) has led to a heightened awareness towards patients' renal function. Whereas detailed guidelines exist for the use of GBCAs in adult patients, best practice is less well defined in children, especially in the very young. We aimed at identifying current practice with regards to the use of GBCAs in children who undergo cardiovascular magnetic resonance.

METHODS

We conducted a worldwide survey among cardiac imagers with pediatric expertise. The questionnaire contained 21 questions covering the imagers' work environments, GBCAs used, monitoring of renal function, and a special emphasis was placed on the practice in neonates.

RESULTS

The survey yielded 70 replies. The single most commonly used GBCA was gadopentetate dimeglumine 34/70 (49%). Among the respondents, the choice of GBCA was more importantly based on availability 26/70 (37%) and approval by a pharmaceutical licensing body that most closely reflects the indication 16/70 (23%) than image quality 7/70 (10%) and side effect profile 8/70 (11%). 55/70 (79%) of respondents performed scans in neonates <1 week of age and 52/55 (95%) of them used GBCA in neonates. 65/70 (93%) respondents at least assess some of their patients' renal functions. Formula-based estimate of glomerular filtration rate is the most popular assessment method 35/65 (54%). In patients with a glomerular filtration rate < 30 ml/min/1.73 m(2) 62/70 (89%) of respondents do not administer gadolinium at all. The single most common side effect of gadolinium was noted to be nausea/emesis 34/57 (60%) followed by discomfort at injection site 17/57 (30%).

CONCLUSIONS

Cardiac imagers are aware of the immature renal function and physiological differences of their pediatric patients that place them at risk for NSF. Epidemiological data is needed for pediatric cardiovascular licensure of gadolinium compounds and for the creation of practice guidelines which will replace current-day practice based on individual clinical judgment.

New insights into the mechanisms of innate immune receptor signalling in fibrosis

Recent advances in our understanding of innate immunity and inflammation have direct bearing on how we understand autoimmunity, and fibrosis, and how innate immune sensors might stimulate both of these key features of several fibrotic diseases. Toll-like receptors (TLRs) are the major receptors for recognizing pathogen associated molecular patterns present on bacterial cell walls, such as LPS, and nucleic acids (RNA and DNA). Several intracellular pathways mediate TLR effects and initiate various pro-inflammatory programs. Mechanisms for control of inflammation, matrix remodeling, and ultimately fibrosis are also activated. Transforming growth factor-beta (TGF-β), Interleukin-1 (IL-1), interleukin-4 (IL-4), interleukin-6 (IL-6), interleukin-13 (IL-13), and interferon (IFNs) appear particularly important in regulating pro-fibrotic aspects of innate immune activation. These mechanisms appear important in fibrotic disease affecting multiple organ-systems, including lung, liver, kidney, and skin. These observations provide new paradigms for understanding the relationship between immunity/inflammation and fibrosis, however, the precise ligand and mechanism linking innate immune sensor(s) to fibrosis remain uncertain in most illnesses.

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.

Comparative in vivo dissociation of gadolinium chelates in renally impaired rats: a relaxometry study

PURPOSE

Investigation of dissociated versus chelated gadolinium (Gd) in plasma, skin, and bone of rats with impaired renal function after administration of ionic macrocyclic (gadoterate or Dotarem) or nonionic linear (gadodiamide or Omniscan) Gd chelates.

MATERIALS AND METHODS

Subtotally nephrectomized Wistar rats were subjected to receive daily injections of 2.5 mmol/kg of Omniscan, gadodiamide without excess ligand caldiamide, Dotarem, or saline (n = 7-10 rats/group) for 5 consecutive days. The Gd concentration was measured by inductively coupled plasma mass spectrometer in skin, femur epiphysis, and plasma on completion of the study (day 11), and dissociated Gd(3+) was measured in the plasma at day 11 (liquid chromatography inductively coupled plasma mass spectrometry). The r(1) relaxivity constant was measured in skin (at day 4 and day 11) and bone (day 11) to investigate the dissociated or chelated form of Gd found in tissue samples. Clinical and skin histopathologic studies were performed.

RESULTS

Subtotal nephrectomy decreased creatinine clearance by 60%. No macroscopic skin lesions were observed in the Dotarem and Omniscan groups in contrast with the gadodiamide group (2 rats survived the study period and 4 of 10 rats showed skin ulcerations and scabs). Skin histopathologic lesions were in the range gadodiamide > Omniscan > Dotarem (similar to control rats). At day 11, the skin Gd concentration was lower in the Dotarem group (161.0 ± 85.5 nmol/g) as compared with the Omniscan (490.5 ± 223.2 nmol/g) and gadodiamide groups (mean value, 776.1 nmol/g; n = 2 survivors). The total Gd concentration in the femur was significantly higher in the Omniscan group than in the Dotarem group. At day 11, the dissociated Gd(3+) concentration in plasma was below the limit of detection in the Dotarem group and was 1.5 ± 0.7 μmol/L in the Omniscan group corresponding to 62% ± 15% of the total Gd concentration. The dissociated Gd(3+) concentration was 1.1 μmol/L in gadodiamide rats (n = 2 survivors). In the skin, the in vivo r1 relaxivity value increased from 4.8 ± 0.7 mM(-1)s(-1) at day 4 to 10.5 ± 3.9 mM(-1)s(-1) at day 11 in the Omniscan group, P < 0.05 (in vitro r(1) in skin, 3.5 mM(-1)s(-1)) and gadodiamide group, whereas no significant change was observed in the Dotarem group (2.8 ± 0.2 and 4.9 ± 2.8 mM(-1)s(-1) at day 4 and 11, respectively, NS) (in vitro value in the skin, 3.2 mM(-1)s(-1)). In the femur, the in vivo r1 relaxivity was higher in the Omniscan group (8.9 ± 2.1 mM(-1)s(-1)) (in vitro relaxivity, 4.5 mM(-1)s(-1)) and gadodiamide group (8.8 mM(-1)s(-1), n = 2 survivors) than in the Dotarem group (3.8 mM(-1)s(-1), n = 1 rat with measurable r(1), since for 7 rats, 1/T(1) - 1/T(1(diamagnetic)) <10% of 1/T(1(diamagnetic)) because of low Gd concentration) (in vitro relaxivity value in the femur matrix, 3.1 mM(-1)s(-1)).

CONCLUSIONS

Unlike Dotarem, Omniscan and gadodiamide induced histologic skin lesions. At day 11, a higher Gd concentration was found in both skin and femur of Omniscan- and gadodiamide-treated rats than in Dotarem-treated rats. Relaxometry results indicate gradual in vivo dechelation and release of dissociated Gd(3+) in a soluble form in renally impaired rats receiving Omniscan and gadodiamide, whereas Dotarem remained stable over the study period.

Nephrogenic systemic fibrosis: current concepts

Nephrogenic systemic fibrosis (NSF) was first described in 2000 as a scleromyxedema-like illness in patients on chronic hemodialysis. The relationship between NSF and gadolinium contrast during magnetic resonance imaging was postulated in 2006, and subsequently, virtually all published cases of NSF have had documented prior exposure to gadolinium-containing contrast agents. NSF has been reported in patients from a variety of ethnic backgrounds from America, Europe, Asia and Australia. Skin lesions may evolve into poorly demarcated thickened plaques that range from erythematous to hyperpigmented. With time, the skin becomes markedly indurated and tethered to the underlying fascia. Extracutaneous manifestations also occur. The diagnosis of NSF is based on the presence of characteristic clinical features in the setting of chronic kidney disease, and substantiated by skin histology. Differential diagnosis is with scleroderma, scleredema, scleromyxedema, graft-versus-host disease, etc. NSF has a relentlessly progressive course. While there is no consistently successful treatment for NSF, improving renal function seems to slow or arrest the progression of this condition. Because essentially all cases of NSF have developed following exposure to a gadolinium-containing contrast agent, prevention of this devastating condition involves the careful avoidance of administering these agents to individuals at risk.

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.

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.

NFκB activation and stimulation of chemokine production in normal human macrophages by the gadolinium-based magnetic resonance contrast agent Omniscan: possible role in the pathogenesis of nephrogenic systemic fibrosis

OBJECTIVE

Nephrogenic systemic fibrosis (NSF) is a generalised fibrotic disorder occurring in certain individuals with renal insufficiency exposed to gadolinium-based contrast agents (GdBCA) for MRI. Histopathological examination of affected tissues shows increased numbers of activated macrophages. To elucidate the mechanisms responsible for macrophage activation, the effects of the GdBCA Omniscan on normal human macrophage global gene expression, chemokine production and nuclear factor κB (NFκB) activation was examined.

METHODS

Normal human monocyte-derived macrophages were incubated with Omniscan (50 mM) and their gene expression analysed by microarrays and real-time PCR. Macrophage chemokine production was assayed by multiplex ELISA. NFκB activation was assessed by NFκB nuclear localisation and quantitation of intracellular levels of inducible nitric oxide synthase (iNOS) protein. A specific cell-permeable NFκB peptide inhibitor was used to abrogate NFκB stimulation of chemokine and iNOS protein levels. CCL8/MCP-2 in affected skin of patients with NSF was examined by indirect immunofluorescence.

RESULTS

Omniscan caused a profound change in the transcriptome of differentiated human normal macrophages in vitro, including a large increase in the expression of genes encoding CC and CXC chemokines. It induced rapid nuclear localisation of NFκB and stimulation of iNOS protein levels and chemokine production which were blocked by an NFκB inhibitory peptide. CCL8/MCP-2, the most upregulated chemokine following in vitro macrophage exposure to Omniscan, was strongly increased in NSF-affected skin.

CONCLUSION

The GdBCA Omniscan induces potent stimulation of macrophage gene expression, NFκB activation and increased NFκB-mediated production of CC and CXC chemokines and iNOS. These alterations may play a crucial role in the pathogenesis of NSF.

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.

Effect of different classes of gadolinium-based contrast agents on control and nephrogenic systemic fibrosis-derived fibroblast proliferation

PURPOSE

To determine the ability of different types of gadolinium-based contrast agents (GBCAs) to stimulate fibroblast proliferation in monolayer cell culture.

MATERIALS AND METHODS

The National Health Service West Glasgow Ethics Committee granted approval for this study. Fibroblasts established from healthy volunteers (control subjects) and from lesional skin of patients with nephrogenic systemic fibrosis were exposed to a range of concentrations of ionic and nonionic linear and macrocyclic contrast agents over 4 days, and the effect on growth was determined. The lowest concentration of contrast agent that stimulated the maximum effect on fibroblast growth was selected for determination of its effect on fibroblast growth over 8 days. The effect of contrast agents on hyaluronan and collagen synthesis was determined with an enzyme-linked immunosorbent assay. Responses were assessed with analysis of variance (general linear model).

RESULTS

The linear gadolinium contrast agents (gadodiamide, gadoversetamide, gadopentetate dimeglumine, and gadobenate dimeglumine) produced a maximum stimulation of fibroblast proliferation at a concentration of 0.1 mmol/L, with cell numbers increasing up to 2.3-fold. The macrocyclic contrast agents (gadoteric acid and gadoteridol) produced a maximum stimulation of fibroblast proliferation at a concentration of 5 mmol/L. The reference gadolinium agents (N-methylglucamine gadolinium ethylenediaminetetraacetic acid and gadolinium trichloride) stimulated fibroblast proliferation at a concentration of 0.01 mmol/L and were toxic at a concentration greater than 1 mmol/L. Growth curves supported the dose-response observations. Hyaluronan synthesis was stimulated by gadoversetamide, gadobenate dimeglumine, gadodiamide, and gadopentetate dimeglumine at a concentration of 0.1 mmol/L and by gadolinium trichloride at a concentration of 0.01 mmol/L, whereas collagen synthesis was unaffected.

CONCLUSION

This study provides evidence that different classes of gadolinium chelates stimulate human fibroblast proliferation.

Persistent activation of dermal fibroblasts from patients with gadolinium-associated nephrogenic systemic fibrosis

BACKGROUND

Nephrogenic systemic fibrosis (NSF) is a systemic fibrotic disorder occurring in some patients with renal insufficiency after exposure to gadolinium-based contrast agents (GdBCA).

OBJECTIVES

To examine cultured NSF dermal fibroblast production and expression of collagens I and III, fibronectin, hyaluronic acid and α-smooth muscle actin (α-SMA) during serial passages and the effects of two GdBCA on collagen gene expression and production by normal dermal fibroblasts.

METHODS

NSF fibroblasts were analysed for expression and production of types I and III collagen, fibronectin, hyaluronic acid and α-SMA. Collagen, type I, α1 (COL1A1) promoter transcription was examined in transient transfections. Nuclear extracts were assayed for binding activity of 108 transcription factors, and specific transcription factor binding was examined by electrophoretic gel mobility assays. Normal fibroblasts were cultured with GdBCA, and collagen expression assessed by real-time PCR and western blots.

RESULTS

NSF fibroblasts displayed a marked increase in collagens I and III, fibronectin and hyaluronic acid production, which was maintained for 9-11 subpassages in vitro. NSF fibroblasts also showed a marked increase in α-SMA expression, twofold higher transcriptional activity of the COL1A1 promoter and increased cREL binding in nuclear extracts compared with normal fibroblasts. GdBCA induced a dose-dependent stimulation of COL1A1 expression and production of type I collagen in normal fibroblasts.

CONCLUSIONS

Fibroblasts from patients with NSF displayed a markedly profibrotic phenotype, which was maintained for several passages in culture. Elevated COL1A1 expression was mediated by transcriptional activation of its promoter associated with increased cREL binding activity. GdBCA stimulated cultured normal fibroblasts to produce increased amounts of collagen.

The functional expression of calcium-sensing receptor in the differentiated THP-1 cells

The expression and function of calcium-sensing receptor (CaSR) in differentiated THP-1 (human acute monocytic leukemia cell line) cells are unknown currently. This study investigated above-mentioned issues using TRAP staining, immunofluorescence staining, Western blotting, ELISA, and Laser Confocal Scanning Microscopy techniques. We found that CaSR protein was expressed, and mainly located in the membrane and cytoplasm in differentiated THP-1 cells. Elevated extracellular calcium or GdCl(3) (an agonist of CaSR) raised intracellular calcium concentration. And this increase was inhibited or abolished by NPS2390 (an inhibitor of CaSR), U73122 (a specific inhibitor of phospholipase C, PLC) or thapsigargin (a Ca(2+)-ATPase inhibitor). The extracellular GdCl(3) elevation stimulated both of IL-1beta and TNFalpha release, and this effect of GdCl(3) was inhibited by NPS2390. In conclusion, CaSR is functionally expressed in differentiated THP-1 cells, and the activated CaSR contributes to intracellular calcium increment through Gq-PLC- inositol triphosphate (IP3) pathway and commits to cytokine secretion. These results suggest that CaSR might be involved in a variety of pathological processes mediated by activated monocyte-macrophages.