Recombinant human pentraxin-2 therapy in patients with idiopathic pulmonary fibrosis: safety, pharmacokinetics and exploratory efficacy.

Abnormal fibrogenic repair response upon alveolar injury is believed to play an important role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). PRM-151 (recombinant human pentraxin-2, also known as serum amyloid P), has been shown to reduce fibrosis in preclinical lung fibrosis models, and was well tolerated with a favourable pharmacokinetic profile in an earlier single-dose phase I study.A randomised, double-blind, placebo-controlled, multiple ascending dose trial was performed to assess the tolerability and pharmacokinetic and pharmacodynamic characteristics of multiple doses of PRM-151 in IPF patients. Subjects in three successive cohorts (1, 5, or 10 mg·kg(-1) versus placebo) received intravenous study drug on days 1, 3, 5, 8 and 15, and were followed-up to day 57.PRM-151 was well tolerated at all dose levels, with no serious adverse reactions. Administration of PRM-151 resulted in two- to eight-fold dose-dependent increases in circulating pentraxin-2 levels. Forced vital capacity and 6-min walk test showed trends towards improvement in the combined PRM-151 dose groups. On high-resolution computed tomography scans, stable or improved lung volume unoccupied by interstitial lung abnormality was noted in some PRM-151 subjects compared to placebo subjects on day 57.The efficacy of PRM-151 in IPF remains to be investigated in dedicated future trials.

Prototypic long pentraxin PTX3 is present in breast milk, spreads in tissues, and protects neonate mice from Pseudomonas aeruginosa lung infection.

Newborns and infants present a higher susceptibility to infection than adults, a vulnerability associated with deficiencies in both the innate and adaptive immune systems. Innate immune receptors are sensors involved in the recognition and elimination of microbes that play a pivotal role at the interface between innate and adaptive immunity. Pentraxin 3 (PTX3), the prototypic long pentraxin, is a soluble pattern recognition receptor involved in the initiation of protective responses against selected pathogens. Because neonates are generally resistant to these pathogens, we suspected that PTX3 may be provided by a maternal source during the early life times. We observed that human colostrum contains high levels of PTX3, and that mammary epithelial cell and CD11b(+) milk cells constitutively produce PTX3. Interestingly, PTX3 given orally to neonate mice was rapidly distributed in different organs, and PTX3 ingested during lactation was detected in neonates. Finally, we observed that orally administered PTX3 provided protection against Pseudomonas aeruginosa lung infection in neonate mice. Therefore, breastfeeding constitutes, during the early life times, an important source of PTX3, which actively participates in the protection of neonates against infections. In addition, these results suggest that PTX3 might represent a therapeutic tool for treating neonatal infections and support the view that breastfeeding has beneficial effects on the neonates' health.

Recombinant human serum amyloid P in healthy volunteers and patients with pulmonary fibrosis.

PRM-151, recombinant human Pentraxin-2 (PTX-2) also referred to as serum amyloid P (SAP), is under development for treatment of fibrosis. A First-in-Human (FIH) trial was performed to assess the safety, tolerability, and pharmacokinetics of single ascending intravenous doses of PRM-151 administered to healthy subjects, using a randomized, blinded, placebo controlled study design. Each cohort included three healthy subjects (PRM-151:placebo; 2:1). SAP levels were assessed using a validated ELISA method, non-discriminating between endogenous and exogenous SAP. At a dose level of 10 mg/kg, at which a physiologic plasma level of SAP was reached, two additional healthy volunteers and three pulmonary fibrosis (PF) patients were enrolled enabling comparison of the pharmacokinetic SAP profile between healthy volunteers and PF patients. In addition, the percentage of fibrocytes (CD45+/Procollagen-1+ cells) in whole blood samples was assessed to demonstrate biological activity of PRM-151 in the target population. PRM-151 administration was generally well tolerated. In two pulmonary fibrosis patients non-specific, transient skin reactions (urticaria and erythema) were observed. PRM-151 administration resulted in a 6-to 13-fold increase in mean baseline plasma SAP levels at dose levels of 5, 10, and 20 mg/kg. The estimated t1/2 of PRM-151 in healthy volunteers was 30 h. Pharmacokinetic profiles were comparable between healthy volunteers and PF patients. PRM-151 administration resulted in a 30-50% decrease in fibrocyte numbers 24 h post-dose. This suggests that administration of PRM-151 may be associated with a reduction of fibrocytes in PF patients, a population for which current pharmacotherapeutic options are limited. The pharmacological action of PRM-151 should be confirmed in future research.

Diagnostic performance and prognostic value of extravascular retention of 123I-labeled serum amyloid P component in systemic amyloidosis.

UNLABELLED: Serum amyloid P component (SAP) binds to amyloid. (123)I-SAP scintigraphy is used to evaluate the extent and distribution of amyloid in systemic amyloidosis and has great clinical value in the detection of systemic amyloidosis. The aim of the study was to assess during scintigraphy the diagnostic performance and prognostic value of a simple parameter describing extravascular (123)I-SAP retention in systemic amyloidosis. METHODS: Two hundred megabecquerels of (123)I-labeled human SAP was injected intravenously for scintigraphy in 20 controls and in 189 consecutive patients with systemic and localized amyloidosis. Extravascular retention of (123)I-SAP was quantified from serum and urine measurements after 24 h (EVR(24)) and 48 h. Sensitivity and specificity were assessed, and retention was correlated with kidney, heart, liver, and nerve involvement and with survival. RESULTS: The cutoff value representing a desired specificity of 90% of EVR(24) was 50%. The associated sensitivity of EVR(24) for detecting reactive systemic, immunocyte-derived (AL), and hereditary amyloidosis was 65%, 61%, and 22%, respectively, using a cutoff point of 50%. In AL amyloidosis, the EVR(24) increased with the number of organs involved (from a mean of 43% for 1 organ to a mean of 81% for 4 organs). The EVR(24) correlated with serum alkaline phosphatase (r = 0.63) and with creatinine clearance (r = -0.36). In AL amyloidosis, both cardiac involvement (hazard ratio, 3.9; 95% CI, 2.0-7.8) and EVR(24) (hazard ratio, 2.0; 95% CI, 1.1-3.9) were independent predictors of survival. CONCLUSION: In AL amyloidosis, the EVR(24) is strongly associated with organ involvement and with prognosis and might serve as an indicator of the body amyloid load. Quantification of SAP retention using the EVR(24) has no additional value over (123)I-SAP scintigraphy in the detection of systemic amyloidosis.

Micro-imaging of amyloid in mice.

Scintigraphic imaging of radioiodinated serum amyloid P-component is a proven method for the clinical detection of peripheral amyloid deposits (Hawkins et al., 1990). However, the inability to perform comparably high-resolution studies in experimental animal models of amyloid disease has impacted not only basic studies into the pathogenesis of amyloidosis but also in the preclinical in vivo evaluation of potential anti-amyloid therapeutic agents. We have developed microimaging technologies, implemented novel computational methods, and established protocols to generate high-resolution images of amyloid deposits in mice. (125)I-labeled serum amyloid P component (SAP) and an amyloid-fibril reactive murine monoclonal antibody (designated 11-1F4) have been used successfully to acquire high-resolution single photon emission computed tomographic (SPECT) images that, when fused with x-ray computed tomographic (CT) data, have provided precise anatomical localization of secondary (AA) and primary (AL) amyloid deposits in mouse models of these diseases. This chapter will provide detailed protocols for the radioiodination and purification of amyloidophilic proteins and the generation of mouse models of AA and AL amyloidosis. A brief description of the available hardware and the parameters used to acquire high-resolution microSPECT and CT images is presented, and the tools used to perform image reconstruction and visualization that permit the analysis and presentation of image data are discussed. Finally, we provide established methods for measuring organ- and tissue-specific activities with which to corroborate the microSPECT and CT images.

Cardiovascular magnetic resonance in cardiac amyloidosis.

BACKGROUND: Cardiac amyloidosis can be diagnostically challenging. Cardiovascular magnetic resonance (CMR) can assess abnormal myocardial interstitium. METHODS AND RESULTS: Late gadolinium enhancement CMR was performed in 30 patients with cardiac amyloidosis. In 22 of these, myocardial gadolinium kinetics with T1 mapping was compared with that in 16 hypertensive controls. One patient had CMR and autopsy only. Subendocardial T1 in amyloid patients was shorter than in controls (at 4 minutes: 427+/-73 versus 579+/-75 ms; P<0.01), was shorter than subepicardium T1 for the first 8 minutes (P< or =0.01), and was correlated with markers of increased myocardial amyloid load, as follows: left ventricular (LV) mass (r=-0.51, P=0.013); wall thickness (r=-0.54 to -0.63, P<0.04); interatrial septal thickness (r=-0.52, P=0.001); and diastolic function (r=-0.42, P=0.025). Global subendocardial late gadolinium enhancement was found in 20 amyloid patients (69%); these patients had greater LV mass (126+/-30 versus 93+/-25 g/m2; P=0.009) than unenhanced patients. Histological quantification showed substantial interstitial expansion with amyloid (30.5%) but only minor fibrosis (1.3%). Amyloid was dominantly subendocardial (42%) compared with midwall (29%) and subepicardium (18%). There was 97% concordance in diagnosis of cardiac amyloid by combining the presence of late gadolinium enhancement and an optimized T1 threshold (191 ms at 4 minutes) between myocardium and blood. CONCLUSIONS: In cardiac amyloidosis, CMR shows a characteristic pattern of global subendocardial late enhancement coupled with abnormal myocardial and blood-pool gadolinium kinetics. The findings agree with the transmural histological distribution of amyloid protein and the cardiac amyloid load and may prove to have value in diagnosis and treatment follow-up.

Human serum amyloid P component attenuates the bacterial lipopolysaccharide-induced increase in blood-brain barrier permeability in mice.

Endotoxin challenge leads to septic shock, multi-organ failure and death in mice. Permeability of the blood-brain barrier (BBB) is increased by endotoxemia. Serum amyloid P component (SAP) is a lipopolysaccharide (LPS)-binding protein that can modulate the host reactions during infections. It is controversial whether SAP can protect from LPS toxicity in vivo or not. We have tested the effect of human SAP on BBB permeability of Salmonella typhimurium LPS-injected mice. The animals showed signs of sickness behaviour including immobility, anorexia, and diarrhoea. Intraperitoneally administered LPS increased the BBB permeability for sodium fluorescein for about 4-fold, and for albumin for more than 2-fold in brain cortex. SAP, given intravenously, had no effect on basal BBB permeability for albumin, although it decreased sodium fluorescein extravasation to brain tissue. In LPS-treated mice, SAP administration alleviated the symptoms of septic shock, and significantly inhibited the enhanced BBB permeability for both tracers. Our data indicate that human SAP may counteract the toxic effects of LPS during septic shock.

Serum amyloid P component scintigraphy for diagnosis and monitoring amyloidosis.

Serum amyloid P component is a normal plasma protein and a universal non-fibrillar constituent of amyloid deposits. Radiolabelled serum amyloid P component scintigraphy is a non-invasive and quantitative method for imaging amyloid deposits, which produces diagnostic images in most patients with systemic amyloidosis, and can be used repeatedly to monitor the course of the disease. The scintigraphy technique and biopsy histology are complementary, providing a detailed microscopic analysis and a quantitative whole body survey respectively. Clinically useful observations provided by the imaging method include different organ distributions of amyloid in different types of the disease, demonstration of amyloid in anatomic sites not available for biopsy, and evidence for rapid progression and sometimes regression of amyloid deposits with different rates in different organs. Labelled serum amyloid P component studies thus make a unique contribution to the diagnosis and management of individual patients with systemic amyloidosis, and to systematic studies of existing and novel therapies. The technique is available routinely for all known or suspected cases of amyloidosis in the NHS National Amyloidosis Centre at the Royal Free Hospital, but it has not been developed commercially.

Transthyretin Leu12Pro is associated with systemic, neuropathic and leptomeningeal amyloidosis.

We report a middle-aged woman with a novel transthyretin (TTR) variant, Leu12Pro. She had extensive amyloid deposition in the leptomeninges and liver as well as the involvement of the heart and peripheral nervous system which characterizes familial amyloid polyneuropathy caused by variant TTR. Clinical features attributed to her leptomeningeal amyloid included radiculopathy, central hypoventilation, recurrent subarachnoid haemorrhage, depression, seizures and periods of decreased consciousness. MRI showed a marked enhancement throughout her meninges and ependyma, and TTR amyloid deposition was confirmed by meningeal biopsy. The simultaneous presence of extensive visceral amyloid and clinically significant deposits affecting both the peripheral and central nervous system extends the spectrum of amyloid-related disease associated with TTR mutations. The unusual association of severe peripheral neuropathy with symptoms of leptomeningeal amyloid indicates that leptomeningeal amyloidosis should be considered part of the syndrome of TTR-related familial amyloid polyneuropathy.

Echocardiographic assessment of cardiac involvement in systemic AL amyloidosis in relation to whole body amyloid load measured by serum amyloid P component (SAP) clearance.

The severity of cardiac infiltration in AL amyloidosis is unrelated to whole body amyloid load as measured by serum amyloid P (SAP) tracer studies. Radiolabeled SAP and echocardiography permit identification of patients with severe cardiac disease with a low whole body load who may be the best candidates for transplantation.

Potential for imaging cerebral amyloid deposits using 123I-labelled serum amyloid P component and SPET.

The systemic and cerebral accumulation of 123I-labelled serum amyloid P component (123I-SAP) was studied in patients with hereditary cerebral amyloid angiopathy-Dutch type (HCHWA-D) to determine the usefulness of 123I-SAP imaging in cerebral amyloidosis. Whole-body and SPET scintigraphic imaging was performed in two patients with HCHWA-D and four controls after the intraveous injection of 123I-SAP. Venous 123I-SAP clearance was also determined. Accumulation of the tracer was observed in the cerebral cortex of both patients, whereas no accumulation was seen in the controls. Blood clearance of radioactivity was similar in the patients and controls, suggesting that the amount of uptake of 123I-SAP in the cerebral amyloid deposits is relatively small. We believe this to be the first demonstration of cerebral amyloid deposits in vivo. Our findings indicate that 123I-SAP scintigraphy has possibilities for the diagnosis of patients with cerebral amyloid diseases, in addition to its use in patients with systemic amyloid deposition.

Plasma kinetics of 125I-labelled amyloid P component in beta 2M amyloidosis: a possible approach to quantitate disease activity.

Dialysis amyloidosis is one of the most incapacitating complications of long-term dialysis treatment. Quantitative assessment of amyloid deposition using radiolabelled tracers has been recently proposed but convincing evidence of its validity in uraemic patients remains to be provided. We studied the plasma kinetics of i.v. administered 125I-labelled serum amyloid P component (125I-SAP) in 20 chronic haemodialysis patients compared with those of nine healthy volunteers and three non-dialysed patients with systemic amyloidosis. Plasma clearance of the tracer was abnormal in 17 of 20 dialysis patients in whom plasma radioactivity declined in a bi-exponential mode, in contrast to the single-exponential slope observed in all healthy controls. 125I-SAP plasma half-life of the second component, probably reflecting metabolic clearance, was significantly prolonged in these dialysis patients compared with the healthy controls (35.3 versus 24.6 h, P < 0.001). Among the long-term haemodialysis patients the calculated extravascular distribution of 125I-SAP was significantly greater in those with severe arthropathy than in asymptomatic patients. These findings demonstrate for the first time that SAP clearance is disturbed in haemodialysis patients due to both failing renal elimination and retention in extravascular sites. The extravascular diffusion is greatly enhanced in patients with clinical evidence of amyloidosis. Therefore the study of plasma 125I-SAP kinetics promises to be a valuable tool to quantitate the extent of amyloidosis.

Studies with radiolabelled serum amyloid P component provide evidence for turnover and regression of amyloid deposits in vivo.

1. Quantitative scintigraphic and turnover studies, utilizing the specific binding affinity of serum amyloid P component for amyloid fibrils, have been developed as a tool for evaluating amyloid deposits in vivo. 2. Serial studies in over 300 patients have shown characteristic, diagnostic tissue distributions of amyloid in different types of amyloidosis. There is generally a poor correlation between quantity of amyloid and associated organ dysfunction. 3. Contrary to previous expectations, regression of amyloid has been demonstrated systematically for the first time: AA, AL and variant transthyretin-associated amyloid deposits often regress rapidly, and sometimes completely, if the supply of fibril protein precursors is substantially reduced.

Studies in vivo and in vitro of serum amyloid P component in normals and in a patient with AA amyloidosis.

Pure serum amyloid P component (SAP) was isolated from a normal donor pool, from individuals with the different genotypes of an MspI restriction fragment length polymorphism (RFLP) linked to the SAP gene, and from a patient with AA amyloidosis. The SAP preparations were all identical and all behaved as a single homogeneous species in polyacrylamide gel electrophoresis, isoelectric focussing, reverse-phase chromatography, binding in vitro to phosphoethanolamine-Sepharose (binding constant 2.4 x 10(7) l/mol) and AL amyloid fibrils (1.6 x 10(8) l/mol), and binding to amyloid deposits in vivo in mice with casein-induced amyloidosis. The in vivo metabolism of 125I-SAP from a single donor was normal and identical in three healthy individuals representing the three different MspI RFLP genotypes. There is thus no frequent polymorphism of SAP in normal subjects, and SAP altered with respect to the characteristics studied here is not a necessary condition for pathogenesis of systemic AA amyloidosis.

Metabolic studies of radioiodinated serum amyloid P component in normal subjects and patients with systemic amyloidosis.

125I-Serum amyloid P component (SAP), injected intravenously into 10 normal subjects, remained predominantly intravascular with mean (SD) T1/2 (half time) in plasma of 24.5 (5.9) h. The fractional catabolic rate of 68 (19)% of the plasma pool per day was more rapid than other reported human plasma proteins. All radioactivity was excreted in the urine by 14 d. In 16 patients with monoclonal gammopathy or chronic inflammatory diseases, but without amyloidosis, 125I-SAP metabolism was normal. However, among 45 patients with biopsy-proven systemic amyloidosis (25, amyloid A type; 20, amyloid L type), 125I-SAP was cleared from the plasma more rapidly, accumulated in the amyloid deposits, and persisted there. The T1/2 in amyloid, measured directly with 131I-SAP, was 24 d. Repeat studies after 6-18 mo were notably consistent in normals but changed significantly in amyloid patients, generally correlating with clinical signs of disease progression. Measurements of 125I-SAP turnover may thus be of value for diagnosis and monitoring of amyloidosis. Analysis of SAP metabolism in amyloidosis suggests that plasma SAP is in dynamic equilibrium with a very large amyloid pool, and in two autopsies the total mass of SAP in the amyloid deposits was 2,100 and 21,000 mg, respectively.

A primed state exists in vivo following histological regression of amyloidosis.

Using a sensitive, quantitative, and non-invasive in vivo method, based on the specific binding of serum amyloid P component to amyloid fibrils, we have directly documented the spontaneous resolution of AA amyloid deposits in mice, and the prolonged existence thereafter of a primed state of enhanced susceptibility to further amyloid deposition. These results may have important implications for understanding and management of amyloidosis in humans.

Specific localization and imaging of amyloid deposits in vivo using 123I-labeled serum amyloid P component.

Highly specific, high-resolution scintigraphic images of amyloid-laden organs in mice with experimentally induced amyloid A protein (AA) amyloidosis were obtained after intravenous injection of 123I-labeled serum amyloid P component (SAP). Interestingly, a much higher proportion (up to 40%) of the injected dose of heterologous human SAP localized to amyloid and was retained there than was the case with isologous mouse SAP, indicating that human SAP binds more avidly to mouse AA fibrils than does mouse SAP. Specificity of SAP localization was established by the failure of the related proteins, human C-reactive protein and Limulus C-reactive protein, to deposit significantly in amyloid and by the absence of human SAP deposition in nonamyloidotic organs. However, only partial correlations were observed between the quantity of SAP localized and two independent estimates, histology and RIA for AA of the amount of amyloid in particular organs. It is not clear which of the three methods used reflects better the extent or clinical significance of the amyloid deposits but in vivo localization of radiolabeled SAP, detectable and quantifiable by gamma camera imaging, is apparently extremely sensitive. These findings establish the use of labeled SAP as a noninvasive in vivo diagnostic probe in experimental amyloidosis, potentially capable of revealing the natural history of the condition, and suggest that it may also be applicable generally as a specific targeting agent for diagnostic and even therapeutic purposes in clinical amyloidosis.