Disentangling inflammatory from fibrotic disease activity by fibroblast activation protein imaging.

OBJECTIVES: To date, there is no valuable tool to assess fibrotic disease activity in humans in vivo in a non-invasive way. This study aims to uncouple inflammatory from fibrotic disease activity in fibroinflammatory diseases such as IgG4-related disease. METHODS: In this cross-sectional clinical study, 27 patients with inflammatory, fibrotic and overlapping manifestations of IgG4-related disease underwent positron emission tomography (PET) scanning with tracers specific for fibroblast activation protein (FAP; 68Ga-FAP inhibitor (FAPI)-04), 18F-fluorodeoxyglucose (FDG), MRI and histopathological assessment. In a longitudinal approach, 18F-FDG and 68Ga-FAPI-04 PET/CT data were evaluated before and after immunosuppressive treatment and correlated to clinical and MRI data. RESULTS: Using combination of 68Ga-FAPI-04 and 18F-FDG-PET, we demonstrate that non-invasive functional tracking of IgG4-related disease evolution from inflammatory towards a fibrotic outcome becomes feasible. 18F-FDG-PET positive lesions showed dense lymphoplasmacytic infiltration of IgG4+ cells in histology, while 68Ga-FAPI-04 PET positive lesions showed abundant activated fibroblasts expressing FAP according to results from RNA-sequencing of activated fibroblasts. The responsiveness of fibrotic lesions to anti-inflammatory treatment was far less pronounced than that of inflammatory lesions. CONCLUSION: FAP-specific PET/CT permits the discrimination between inflammatory and fibrotic activity in IgG4-related disease. This finding may profoundly change the management of certain forms of immune-mediated disease, such as IgG4-related disease, as subtypes dominated by fibrosis may require different approaches to control disease progression, for example, specific antifibrotic agents rather than broad spectrum anti-inflammatory treatments such as glucocorticoids.

First Experience With SPECT/CT Using a 99mTc-Labeled Inhibitor for Prostate-Specific Membrane Antigen in Patients With Biochemical Recurrence of Prostate Cancer.

AIM: Prostate-specific membrane antigen (PSMA) is overexpressed in most prostate cancers (PCs). Here, we report our first experience using the Tc-labeled PSMA inhibitor MIP-1404 (Progenics Pharmaceuticals, Inc, Tarrytown, NY) in 60 patients with biochemically recurrent PC. METHODS: Whole-body planar scintigraphy and SPECT/CT of the lower abdominal pelvic region of 60 patients with biochemical relapse of PC were analyzed retrospectively. In these subjects, an average dose of 733.1 ± 49.5 MBq (19.8 ± 1.3 mCi) Tc-labeled MIP-1404 was injected 4 to 5 hours prior to imaging. In addition to visual evaluation, SUVmax were determined in the tumor lesions using a previously developed protocol for quantitative SPECT/CT. RESULTS: In 42 of 60 patients, Tc-MIP-1404-positive lesions could be detected (70%; 95% confidence interval [CI], 0.58-0.82). Twenty patients had Tc-MIP-1404-positive lymph nodes suggestive of metastasis, 14 patients had pathological uptake in the prostate region indicative of local recurrence, and for another 19 patients, there was tracer accumulation in the skeleton (n = 18) or lungs (n = 1). Detection rate was 91.4% (95% CI, 0.82-1) at prostate-specific antigen levels greater than 2 ng/mL and 40.0% (95% CI, 0.21-0.59) at lower prostate-specific antigen values (P < 0.01). Of the 60 patients, in total, 82 positive lesions were analyzed quantitatively. Average SUVmax of the lesions was 16.3 ± 21.6 with a range of 1.7 to 142.9. CONCLUSION: Tc-labeled PSMA inhibitor MIP-1404 is a promising SPECT tracer for detection of locally recurrent or metastatic prostate cancer.

Tocopherol deficiency in transgenic tobacco (Nicotiana tabacum L.) plants leads to accelerated senescence.

alpha-Tocopherol constitutes the major lipophilic antioxidant in thylakoid membranes, which cooperates with the soluble antioxidant system to alleviate oxidative stress caused by reactive oxygen species (ROS) during oxygenic photosynthesis. Tocopherol accumulates during leaf senescence, indicating the necessity for increased redox buffer capacity in senescent leaves, and tocopherol deficiency has been shown to restrict sugar export from source leaves by inducing callose plugging in the vasculature. We have generated tocopherol-deficient tobacco plants that contain as few as 1% of wild-type (WT) tocopherol in leaves by silencing homogentisate phytyltransferase (HPT). Employing HPT : RNAi plants, we have assessed the importance of tocopherol during leaf senescence and for sugar export. Irrespective of whorl position, the content of free sugars and starch was lower in HPT : RNAi leaves than in WT during the vegetative phase, and no accumulation of callose or a reduction in sugar exudation compared to WT was evident. Based on our observations, we discuss lipid peroxidation as a potential modulator of tocopherol-mediated signalling. Furthermore, senescence was accelerated in lower leaves of HPT transgenics, as indicated by elevated GS1 and reduced rbcS transcript amounts. Oxidative stress was increased in virescent lower source leaves, suggesting that the lack of tocopherol triggers premature senescence.

A role for nitrilase 3 in the regulation of root morphology in sulphur-starving Arabidopsis thaliana.

Arabidopsis thaliana expresses four nitrilases, three of which (NIT1, NIT2 and NIT3) are able to convert indole-3-acetonitrile to indole-3-acetic acid (IAA), the plant growth hormone, while the isozyme NIT4 is a beta-cyano-l-alanine hydratase/nitrilase. NIT3 promoter activity is marginal in leaves or roots of vegetative plants and undetectable in bolting and flowering plants, but its level increases strongly when plants experience sulphur deprivation. No other nitrilase genes respond to sulphur supply/deficiency. Neither N- nor P-deprivation cause detectable changes in NIT3 promoter activity. In transgenic plants expressing uidA under the control of the NIT3 promoter (NIT3p::uidA), sulphate deprivation leads to the appearance of beta-glucuronidase activity in shoots and particularly in roots, most strongly in the conductive tissues and lateral root primordia. Deletion analysis allowed localization of the sulphur-responsive element to a 317 bp segment of the NIT3 promoter encompassing nt -2151 to -1834 upstream of the transcriptional start point. Both nitrilase polypeptide and nitrilase activity were also induced by sulphur starvation. NIT3 promoter activity was strongly induced by O-acetylserine, suggesting that, as is the case with enzymes of sulphate assimilation, sulphate deficiency may be communicated to NIT3 via an increase in the level of the cysteine precursor, O-acetylserine. During sulphur deprivation, a preferential depletion of the pool of the indole-3-acetonitrile precursor glucobrassicin compared with that of total glucosinolates was noticed. In the absence of an external sulphate supply, plants developed longer roots with a higher number of lateral roots. The increased growth of the root system occurred at the expense of shoot growth which was retarded under conditions of sulphur starvation. Taken together, these results suggest that a regulatory loop appears to exist by which sulphate deficiency, through an increase in glucobrassicin turnover and nitrilase 3 accumulation, initiates the production of extra auxin leading to increased root growth and branching, thus allowing the root system to penetrate new areas of soil effectively to gain access to fresh supplies of sulphur.