Quantifying the effect of nutritional interventions on metabolic resilience using personalized computational models

The manifestation of metabolic deteriorations that accompany overweight and obesity can differ greatly between individuals, giving rise to a highly heterogeneous population. This inter-individual variation can impede both the provision and assessment of nutritional interventions as multiple aspects of metabolic health should be considered at once. Here, we apply the Mixed Meal Model, a physiology-based computational model, to characterize an individual's metabolic health in silico. A population of 342 personalized models were generated using data for individuals with overweight and obesity from three independent intervention studies, demonstrating a strong relationship between the model-derived metric of insulin resistance (ρ = 0.67, p < 0.05) and the gold-standard hyperinsulinemic-euglycemic clamp. The model is also shown to quantify liver fat accumulation and β-cell functionality. Moreover, we show that personalized Mixed Meal Models can be used to evaluate the impact of a dietary intervention on multiple aspects of metabolic health at the individual level.

Applying Statistical Methods to Identify Variables Associated With a Beneficial Physiological Response to Fish Oil Intervention

Objectives

The primary goal of this analysis was to use baseline and pre-intervention variables from a large dietary intervention study (the FINGEN study) to develop models to predict change in levels of plasma triglycerides (TG), and in the plasma long-chain polyunsaturated fatty acids eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA), after fish oil supplementation. A secondary goal was whether clustering of baseline and pre-intervention data could lead to identification of groups of participants who responded differentially.

Methods

All statistical analyses were undertaken in R, with outcomes of interest kept on a continuous scale. Multiple imputation was conducted which generated 5 complete datasets. Variable selection methods (forward stepwise selection, backward stepwise selection, LASSO and the Boruta algorithm) were applied across each imputed dataset to generate models. Validation methods were applied to minimise model overfitting. Validation set root mean squared errors (RMSEs) were averaged across the 5 imputed datasets, with final model chosen corresponding to the lowest RMSE and therefore most accurate predictions on data not included in model development.

Results

The final model for predicting TG change contained the predictors pre-intervention TG and baseline fasting insulin and ApoB levels. For EPA + DHA change, these were pre-intervention EPA, DHA and baseline ApoE levels. Both models explained over 40% of variation in the outcome, generated using forward stepwise selection. Unsupervised analysis using baseline and pre-intervention data did not lead to significant differences in the outcomes between clusters.

Conclusions

Our models successfully identified predictors of response for plasma triglyceride and EPA + DHA change upon intervention with fish oil. This analysis approach therefore offers opportunities as a tool for precision nutrition approaches, to determine those most likely to respond beneficially to dietary interventions.

Funding Sources

Biotechnology and Biological Sciences Research Council (BBSRC) UK and Unilever Foods Innovation Centre, Wageningen, The Netherlands: Collaborative Training Partnership (CTP) PhD.

Effect of granulocyte colony-stimulating factor (G-CSF)-supported chemotherapy on MR imaging of normal red bone marrow in breast cancer patients with focal bone metastases

Purpose: To investigate the effect of granulocyte colony-stimulating factor (G-CSF)-supported chemotherapy on normal red bone marrow MR imaging in breast cancer patients with focal bone metastases.

Material and Methods: Fifteen breast cancer patients who were examined before and after chemotherapy with T1-weighted-SE and long echo-time inversion-recovery turbo-spin-echo (long TE IR-TSE) sequences in the thoracolumbar spine and pelvis were retrospectively studied. Nine of them received G-CSF therapy after the administration of each chemotherapy course. Of these 9 patients, the MR follow-ups were performed during G-CSF in 4 patients and after G-CSF therapy in 5 patients. Six patients did not receive G-CSF. Signal intensity (SI) changes in normal bone marrow were evaluated visually in all patients and quantitatively in 13 patients.

Results: In all 4 patients investigated during G-CSF therapy a diffuse, homogeneous SI increase on long TE IR-TSE was observed visually and quantitatively in initially normal bone marrow. This change obscured some focal lesions in 2 patients. No such SI change was visible after G-CSF therapy ( p = 0.008) or in patients not receiving G-CSF. On T1-weighted images an SI decrease was found both during and after G-CSF therapy, but an increase occurred in patients not receiving G-CSF.

Conclusion: G-CSF-supported chemotherapy can induce diffuse SI changes in normal red bone marrow on MR imaging. On long TE IR-TSE, the changes are visible during G-CSF treatment and can lead to misinterpretations in the response evaluation of bone metastases to therapy.

HER-2 overexpression (3+) in patients with squamous cell esophageal carcinoma correlates with poorer survival

The incidence of esophageal carcinoma is increasing worldwide. In Sweden, approximately 400 patients are diagnosed each year. The present study retrospectively investigates survival in 97 patients with esophageal carcinoma in regard to their HER-2 status as examined by immunohistochemistry (IHC) and chromogen in situ hybridization (CISH). Sixty-eight patients had localised disease and 29 patients had advanced disease. Seventy patients had squamous cell carcinoma, and nine of these patients (13%) had HER-2 overexpression (3+). Eight (30%) of 27 adenocarcinoma patients overexpressed (3+) HER-2. In patients overexpressing (3+) HER-2 a statistical trend towards poorer survival was observed (P = 0.057). In squamous cell carcinoma patients, HER-2 overexpression (3+) correlated with poorer survival (P = 0.035), whereas in adenocarcinoma patients, HER-2 status (3+) did not. HER-2 amplification according to CISH was present in five (two squamous cell carcinomas and three adenocarcinomas) out of 17 HER-2 overexpressing (3+) tumours. In conclusion, HER-2 overexpression (3+) seems to be associated with poorer survival in esophageal carcinomas, especially in patients with squamous cell esophageal carcinoma.

Sentinel node lymphocytes: tumour reactive lymphocytes identified intraoperatively for the use in immunotherapy of colon cancer

The sentinel node is the first lymph node to receive lymphatic drainage from a tumour and is usually the first site of metastases. Today, the sentinel node is used for tumour staging. Here, we focus on its immunological role and investigate lymphocytic function in sentinel nodes, identified intraoperatively by peritumoural dye injection, from 15 patients with colon cancer. Tumour infiltrating lymphocytes, sentinel and nonsentinel lymph node cells and peripheral blood leukocytes were studied by flow cytometry, proliferation assays and interferon-γ secretion after activation with autologous tumour homogenate. Whereas tumour-infiltrating lymphocytes were nonresponsive in the proliferation assays, lymphocytes from sentinel nodes proliferated dose dependently and secreted interferon-γ upon stimulation with tumour homogenate. The responses were of varying magnitude and tended to be weaker in metastatic sentinel nodes. Sentinel node lymphocytes represents an enriched source of tumour reactive lymphocytes, and may be useful in future trials of adoptive immunotherapy.

Eosinophil granulocytes are activated during the remission phase of ulcerative colitis

AIM

The aim of this study was to establish a method of investigating intestinal eosinophil and neutrophil granulocytes by flow cytometry, and to compare the distribution and activity of these cells in different stages of ulcerative colitis (UC).

METHODS

Biopsy samples were taken from six locations of the entire colon and from the terminal ileum in 10 patients with active total UC, 10 patients with inactive total UC, eight patients with active distal UC, and 11 control subjects. Cell suspensions from biopsies and from peripheral blood were incubated with fluorophore conjugated monoclonal antibodies. The use of scatter plot-gating and specific antibodies was established in a flow cytometry assay.

RESULTS

Eosinophils were more numerous and more active in patients with active UC than in controls. Interestingly, during inactive UC, the number of activated eosinophils was even larger. Eosinophil activity was high in the rectum of patients with distal colitis but was also slightly elevated in the proximal colon. Neutrophils were increased in number and activity during active but not inactive UC. In patients with distal colitis, activated neutrophils were only found in the sigmoid colon and rectum.

CONCLUSION

With this method, we confirm that neutrophils participate in the inflammatory process during active UC, and that they express a resting phenotype during remission. The finding of activated eosinophils in inflamed intestine strengthens the view of these cells as proinflammatory and tissue damaging. Nevertheless, our new finding of high eosinophil activation during inactive UC suggests that eosinophils play a role in repair of injured epithelium.

Combining information obtained from magnetic resonance imaging and conventional radiographs to detect sacroiliitis in patients with recent onset inflammatory back pain

OBJECTIVE

To compare the contribution of changes on magnetic resonance imaging (MRI) and conventional radiography (CR) in the sacroiliac joints of patients with recent onset inflammatory back pain (IBP) in making an early diagnosis of spondyloarthritides.

METHODS

The study involved 68 patients with IBP (38% male; mean (SD) age, 34.9 (10.3) years) with symptom duration less than two years. Coronal MRI of the sacroiliac joints was scored for inflammation and structural changes, and pelvic radiographs were scored by the modified New York (mNY) grading. Agreement between MRI and CR was analysed by cross tabulation per sacroiliac joint and per patient.

RESULTS

A structural change was detected in 20 sacroiliac joints by MRI and in 37 by CR. Inflammation was detected in 36 sacroiliac joints by MRI, and 22 of these showed radiographic sacroiliitis. Fourteen patients fulfilled the mNY criteria based on CR. Classification according to the modified New York criteria would be justified for eight patients if it was based on MRI for structural changes only, for 14 if it was based on structural changes on CR, for 14 (partly) different patients if it was based on inflammation on MRI only, for 16 if it was based on inflammation and structural changes on MRI, for 19 if it was based on inflammation on CR combined with MRI, and for (the same) 19 if it was based on inflammation and structural damage on CR combined with MRI.

CONCLUSIONS

CR can detect structural changes in SI joints with higher sensitivity than MRI. However, inflammation on MRI can be found in a substantial proportion of patients with IBP but normal radiographs. Assessment of structural changes by CR followed by assessment of inflammation on MRI in patients with negative findings gives the highest returns for detecting involvement of the SI joints by imaging in patients with recent onset IBP.

Association between radiographic damage of the spine and spinal mobility for individual patients with ankylosing spondylitis: can assessment of spinal mobility be a proxy for radiographic evaluation?

OBJECTIVE

To demonstrate the association between various measures of spinal mobility and radiographic damage of the spine in individual patients with ankylosing spondylitis, and to determine whether the assessment of spinal mobility can be a proxy for the assessment of radiographic damage.

METHODS

Radiographic damage was assessed by the mSASSS. Cumulative probability plots combined the radiographic damage score of an individual patient with the corresponding score for nine spinal mobility measures. Receiver operating characteristic analysis was performed to determine the cut off level of every spinal mobility measure that discriminates best between the presence and absence of radiographic damage. Three arbitrary cut off levels for radiographic damage were investigated. Likelihood ratios were calculated to explore further the diagnostic properties of the spinal mobility measures.

RESULTS

Cumulative probability plots showed an association between spinal mobility measures and radiographic damage for the individual patient. Irrespective of the chosen cut off level for radiographic progression, lateral spinal flexion and BASMI discriminated best between patients with and those without structural damage. Even the best discriminatory spinal mobility assessments misclassified a considerable proportion of patients (up to 20%). Intermalleolar distance performed worst (up to 30% misclassifications). Lateral spinal flexion best predicted the absence of radiographic damage, and a modified Schober test best predicted the presence of radiographic damage.

CONCLUSION

This study unequivocally demonstrated a relationship between spinal mobility and radiographic damage. However, spinal mobility cannot be used as a proxy for radiographic evaluation in an individual patient.

Chemical-shift micro-imaging of subcutaneous lesions

A chemical-shift imaging technique was used for the study of small subcutaneous lesions. This study concerns micro-imaging of two females suffering from a tenosynovial giant cell tumor and an epidermal cyst. High-resolution water, fat and chemical-shift artifact-free images were obtained on a whole-body MR unit (1.5 T) equipped with a 23-mm microscopy surface coil and standard gradients (23 mT/m). A significant improvement in signal-to-noise ratio was achieved by reducing the receiver bandwidth to values below +/-10 kHz. The image data sets were acquired with resolution 0.1 x 0.13 mm in the plane, slice thickness 0.5 mm and with acquisition time less than 3 min. Spatial resolution, fat suppression, image texture and edge delineation were improved on spectroscopic images compared with those on conventional MR images.

Clinical and subclinical intestinal inflammation assessed by the mucosal patch technique: studies of mucosal neutrophil and eosinophil activation in inflammatory bowel diseases and irritable bowel syndrome

BACKGROUND AND AIMS

There is a clear need for a rapid, simple, safe, and sensitive method of determining the type and intensity of inflammation in the gut mucosa in clinical practice. In this study, we have evaluated the potential of a new method, the mucosal patch technique, in patients with and without apparent gut inflammation, as assessed by conventional diagnostic procedures.

SUBJECTS AND METHODS

The technique tested is based on the idea that inflammatory mediators released from the rectal mucosa can be absorbed by and then extracted from cellulose patches brought into contact with the mucosa by use of an instrument with an inflatable balloon. Measurements were performed in healthy controls (n = 16) and in patients with active (n = 19) and inactive ulcerative colitis (UC, n = 8), collagen colitis (CC, n = 12), coeliac disease (n = 13), and irritable bowel syndrome (IBS, n = 13).

RESULTS

Inflammatory mediators from neutrophils (myeloperoxidase (MPO)) and eosinophils (eosinophil cationic protein (ECP)) were increased on average 300- and 10-fold, respectively, in patients with active UC compared with healthy controls and were correlated with the endoscopic score. Patients with inactive UC, CC, coeliac disease, and IBS exhibited no endoscopic signs of inflammation. These patient groups had significantly lower levels of MPO and ECP than the active UC group but showed on average a four- to sevenfold increase in MPO compared with healthy controls.

CONCLUSION

The mucosal patch technique was well tolerated by patients and easily applied by the investigator. Pronounced neutrophil and eosinophil involvement in UC was demonstrated. With the high sensitivity of the technique, low degree mucosal neutrophil activation could also be quantified in patients with CC and UC in clinical remission. The finding of increased neutrophil involvement in patients with IBS contributes to the pathophysiological ideas of this disease.

Scoring of radiographic progression in randomised clinical trials in ankylosing spondylitis: a preference for paired reading order

OBJECTIVES

To describe the influence of the reading order (chronological v paired) on radiographic scoring results in ankylosing spondylitis. To investigate whether this method is sufficiently sensitive to change because paired reading is requested for establishing drug efficacy in clinical trials.

METHODS

Films obtained from 166 patients (at baseline, 1 year, and 2 years) were scored by one observer, using the modified Stoke Ankylosing Spondylitis Spinal Score. Films were first scored chronologically, and were scored paired 6 months later.

RESULTS

Chronological reading showed significantly more progression than paired reading both at 1 year (mean (SD) progression 1.3 (2.6) v 0.5 (2.4) units) and at 2 years (2.1 (3.9) v 1.0 (2.9) units); between-method difference: p<0.001 at 1 year, and p<0.001 at 2 years. After 1 year, progression (>0 units) was found in 35/166 (21%) patients after paired reading and in 55/166 (33%) after chronological reading. After 2 years, these figures were 50/166 (30%) and 68/166 (41%), respectively. Sample size calculations showed that 94 patients in each treatment arm are required in a randomised clinical trial (RCT) to provide sufficient statistical power to detect a difference in 2 year progression if films are scored paired.

CONCLUSION

Reading with chronological time order is more sensitive to change than reading with paired time order, but paired reading is sufficiently sensitive to pick up change with a follow up of 2 years, resulting in an acceptable sample size for RCTs.

How the type of risk reduction influences required sample sizes in randomised clinical trials

To increase change between groups, randomised clinical trials (RCT) often include patients with high risk for a particular outcome, by inclusion criteria that select predictors for that outcome. This increases the statistical power, and fewer patients are required for that RCT. The way in which patient selection influences the power, and thus sample size required, depends on how an intervention reduces the individual risk: by an absolute or relative risk reduction model.

Effect of granulocyte colony-stimulating factor (G-CSF)-supported chemotherapy on MR imaging of normal red bone marrow in breast cancer patients with focal bone metastases

PURPOSE

To investigate the effect of granulocyte colony-stimulating factor (G-CSF)-supported chemotherapy on normal red bone marrow MR imaging in breast cancer patients with focal bone metastases.

MATERIAL AND METHODS

Fifteen breast cancer patients who were examined before and after chemotherapy with T1-weighted-SE and long echo-time inversion-recovery turbo-spin-echo (long TE IR-TSE) sequences in the thoracolumbar spine and pelvis were retrospectively studied. Nine of them received G-CSF therapy after the administration of each chemotherapy course. Of these 9 patients, the MR follow-ups were performed during G-CSF in 4 patients and after G-CSF therapy in 5 patients. Six patients did not receive G-CSF. Signal intensity (SI) changes in normal bone marrow were evaluated visually in all patients and quantitatively in 13 patients.

RESULTS

In all 4 patients investigated during G-CSF therapy a diffuse, homogeneous SI increase on long TE IR-TSE was observed visually and quantitatively in initially normal bone marrow. This change obscured some focal lesions in 2 patients. No such SI change was visible after G-CSF therapy (p = 0.008) or in patients not receiving G-CSF. On T1-weighted images an SI decrease was found both during and after G-CSF therapy, but an increase occurred in patients not receiving G-CSF.

CONCLUSION

G-CSF-supported chemotherapy can induce diffuse SI changes in normal red bone marrow on MR imaging. On long TE IR-TSE, the changes are visible during G-CSF treatment and can lead to misinterpretations in the response evaluation of bone metastases to therapy.

Presence of polymorphonuclear granulocytes during the early stage of transplant arteriosclerosis after prolonged ischemia in the rat

The presence and function of polymorphonuclear granulocytes has been investigated, in particular, in the microcirculation in many short-term models of ischaemia/reperfusion injury. The aim of this study was to examine the presence of granulocytes in the aorta in a recently established long-term model of transplant arteriosclerosis, based on prolonged cold graft ischaemia time in the rat. Aortic grafts of PVG donors were subjected to two different cold ischaemia times of 1 and 4 h (n = 5 in each group) before an orthotopic transplantation to syngeneic recipients. The grafts were explanted shortly after various times post-reperfusion (7.5 min 24 h) and examined with conventional staining, immunohistochemistry and transmission electron microscopy for the presence of granulocytes. The results showed the presence of these cells adherent to the endothelial layer or in the subendothelial layer in grafts with both ischaemia times and with a maximum seen 2 h after transplantation. The internal elastic lamina was interrupted at sites of granulocyte adherence. We concluded that the polymorphonuclear granulocyte may be involved in the ischaemia/reperfusion injury in this model, thus, contributing to the development of accelerated transplant arteriosclerosis.

Myocardial fibrosis in polymyositis

Myocardial involvement in polymyositis is commonly suspected in noninvasive studies, but symptomatic cardiac disease is rare. We describe a 27-year-old woman with a 6 year history of severe polymyositis and persistent elevation of creatine phosphokinase-MB isoenzyme who suddenly developed congestive heart failure and bradycardia-tachycardia syndrome. Autopsy revealed severe myocardial fibrosis without inflammatory cell infiltrates concomitant to active polymyositis of the skeletal muscles despite intensive longterm immunosuppressive therapy.

A four-year review of fatal Aspergillosis

To investigate the incidence, underlying diseases, and macropathological and microbiological features of invasive aspergillosis in a university hospital, the protocols of 1187 autopsies performed during the 4-year period 1993-1996 were reviewed. Invasive aspergillosis was diagnosed as the cause of death in 48 (4%) cases, four (8%) of which did not involve severe primary immunosuppression. In seven (15%) cases no pulmonary involvement was found; in six of these cases the portal of infection could not be established, whereas in one case invasive aspergillosis originated from Aspergillus peritonitis. Aspergillus grew in 42% of the samples obtained from the respiratory tracts of 32 patients with pulmonary aspergillosis and submitted within 10 days antemortem; at least one positive culture was obtained from 20 (63%) of these patients. It is concluded that the diagnosis of aspergillosis by means of culture has an appreciable sensitivity. Fatal invasive aspergillosis was rare among patients without severe immunosuppression, whereas invasive aspergillosis without pulmonary involvement was unexpectedly frequent.

Ischemia-induced transplant arteriosclerosis in the rat. Induction of peptide growth factor expression

Peptide growth factors have been reported to contribute to the atherogenic process, and they are known to mediate signals for vascular remodeling. Using syngeneic and allogeneic rat aorta transplant models, we analyzed the impact of cold ischemia time up to 24 hours and reperfusion injury on development of transplant arteriosclerosis during the first 2 months after transplantation. The expression of the transforming growth factor-beta (TGF-beta) family as well as the platelet-derived growth factor (PDGF) and its receptors was studied by use of immunohistochemistry, followed by semiquantitative evaluation and multivariate analysis. In the syngeneically transplanted aortas, the expression of TGF-beta 1, PDGF, and the two PDGF receptors in the neointima increased significantly with the extent of cold ischemia time. Furthermore, there was a significant induction of the latent TGF-beta binding protein in the neointima as well as TGF-beta 2 in the media, both correlating with the observation time after transplantation. In the allogeneic grafts, all examined proteins were already induced strongly 2 weeks after transplantation, even at the shortest ischemic period studied (1 hour). However, no positive correlation between growth factor expression and cold ischemia or observation time could be found. Double immunohistochemistry revealed that macrophages express PDGF and its receptors as well as TGF-beta 1. Smooth muscle cells express both types of PDGF receptors, and a few T cells express TGF-beta 1 as well as PDGF receptors. In summary, TGF-beta and PDGF are induced by allogeneic as well as ischemic stimuli in transplanted aortas, suggesting a role in the pathogenesis of transplant arteriosclerosis and representing a potential target for therapeutic intervention.

Inhibition of transplant arteriosclerosis in rat aortic grafts by low molecular weight heparin derivatives

The effects of low molecular weight heparin derivatives with a low anticoagulant activity on transplant arteriosclerosis (TA) in a rat aortic transplant model were investigated. TA was induced by ischemia in the syngeneic transplants and primarily by immunological mechanisms in the allogeneic transplants. Treatment with the heparin derivatives, OAM 71262 or LA-heparin, was administered in a dosage of 250 micrograms/kg/hr by mini-osmotic pumps during 8 weeks. No immunosuppressive regimen was given to the recipient rats in either model. All rats were killed 8 weeks after aortic grafting. The grafts were examined for intimal and medial changes using an image analysis system. Heparin derivatives had a beneficial effect on both the intimal thickening and the medial injury in the syngeneic transplants, but not in the allogeneic grafts. In the syngeneic LA-heparin treated grafts, the thickness of the intima was less than that in the syngeneic control grafts (P < 0.05). In the syngeneic transplants, a significant increase was observed in the media after treatment with OAM 71262 (P < 0.01) as well as those with LA-heparin (P < 0.001). In the syngeneic grafts treated with both heparin derivatives, a significant reduction in the antigen expression of alpha-actin-containing smooth muscle cells in the intima, transforming growth factor-beta 1 both in the media and adventitia, and platelet-derived growth factor-beta receptors in the adventitia was observed immunohistochemically. In summary, low molecular weight heparin derivatives with low anticoagulant activity partially inhibited ischemia-induced syngeneic TA, whereas no such effect could be demonstrated in nonimmunosuppressed recipients with allogeneic grafts.

Expression of CD11b and ICAM-1 in an in vivo model of transplant arteriosclerosis

Adhesion molecules play a crucial role in transplant rejection in regulating the interaction of inflammatory cells with cells in the vascular wall. In an aortic transplantation model, we have previously analysed the early adhesion process (7.5 min to 24 h) and the impact of cold ischaemia time (1-24 h) upon transplant arteriosclerosis during the first 2 months after transplantation in the rat. The aim of this investigation was to study adhesion molecules in accelerated transplant arteriosclerosis in a rat model by analysing the immunohistochemical expression of CD11b and ICAM-1 up to 2 months and followed by a semiquantitative evaluation and multivariant analysis. Antigen expression of CD11b and ICAM-1 adhesion molecules was stronger in the aortic allografts than in the ischaemia-induced syngeneic aortic grafts in the whole vessel wall. Neither ICAM-1 nor CD11b antigen expression correlated significantly with time periods of ischaemia/reperfusion injury in allogeneic or syngeneic aortic transplants. CD11b and ICAM-1 are induced by allogeneic stimuli in transplanted aortas suggesting a role in the pathogenesis of transplant arteriosclerosis. Our findings have implications for understanding the role of cell adhesion activation in the vascular wall subject to chronic graft rejection.

Ischemia-induced transplant arteriosclerosis in the rat

The effect of cold graft ischemia time on the development of transplant arteriosclerosis was investigated. Aorta grafts from DA or PVG rats were stored in a cold perfusion solution for 1, 4, or 24 hours before being orthotopically transplanted to PVG recipients. After observation times ranging from 2 to 8 weeks, the grafts were examined for various cell populations. Regional changes in the intima and media layers were measured by using an image analysis system. The arteriosclerosis-like changes seen in syngeneic grafts with the longest ischemia time could be almost as prominent as those seen in the allogeneic transplants. The magnitude of the regional intima changes in the syngeneic group correlated well with the ischemia time and in the allogeneic group with the observation time. The cell composition found in the intima and media of the allogeneic vessels consisted of macrophages, T-lymphocytes, MHC class II-expressing cells, and smooth muscle cells, whereas the syngeneic grafts contained almost exclusively smooth muscle cells and macrophages. We therefore conclude that the damage due to prolonged cold ischemia time is sufficient to cause pronounced graft arteriosclerosis. The pathophysiological mechanism leading to ischemia-induced arteriosclerosis is different from the one seen in the allogeneic situation.

Effects of angiopeptin on transplant arteriosclerosis in the rat

The influence of the somatostatin analogue angiopeptin on transplant arteriosclerosis was investigated using two aortic transplantation rat models. One was characterized by ischemia/reperfusion-induced changes in syngeneic transplants while immunologically induced changes dominated in the other allogeneic model. Angiopeptin, 100 micrograms/kg per day, was administered continuously until the sacrifice of the rats after 8 weeks. No additional immunosuppression was used in either model. An image analysis system was used to quantify the intimal and medial thicknesses of the grafts. In the syngeneic grafts, the intimal thickness was less than 50% of that of control grafts (P < 0.05), but no difference was seen in the allogeneic model. The expression of selected cells, TGF-beta s, and PDGF and PDGF alpha-receptors was detected immunohistochemically and displayed a similar picture in control and angiopeptin-treated grafts in both models. We conclude that angiopeptin has no clear immunosuppressive properties but may counteract ischemia-induced transplant arteriosclerosis.

Ischemia-Induced Transplant Arteriosclerosis in the Rat

The effect of cold graft ischemia time on the development of transplant arteriosclerosis was investigated. Aorta grafts from DA or PVG rats were stored in a cold perfusion solution for 1, 4, or 24 hours before being orthotopically transplanted to PVG recipients. After observation times ranging from 2 to 8 weeks, the grafts were examined for various cell populations. Regional changes in the intima and media layers were measured by using an image analysis system. The arteriosclerosis-like changes seen in syngeneic grafts with the longest ischemia time could be almost as prominent as those seen in the al-logeneic transplants. The magnitude of the regional intima changes in the syngeneic group correlated well with the ischemia time and in the allogeneic group with the observation time. The cell composition found in the intima and media of the allogeneic vessels consisted of macrophages, T-lymphocytes, MHC class II-expressing cells, and smooth muscle cells, whereas the syngeneic grafts contained almost exclusively smooth muscle cells and macro-phages. We therefore conclude that the damage due to prolonged cold ischemia time is sufficient to cause pronounced graft arteriosclerosis. The patho-physiological mechanism leading to ischemia-induced arteriosclerosis is different from the one seen in the allogeneic situation. (Arterio-scler Throtnb Vase Biol . 1995;15:145-155.)

Induction of transforming growth factor-beta during cardiac allograft rejection

The polypeptides of the transforming growth factor-beta (TGF-beta) family are potent endogenous immuno-regulators. Using a rat cardiac allograft transplant model, we investigated the expression of the precursor forms of TGF-beta 1, TGF-beta 2, and TGF-beta 3 and the latent TGF-beta binding protein (LTBP) by immunohistochemistry. The activity of TGF-beta in the extracts from transplanted as well as normal hearts was measured using a bioassay, and Northern blot analysis was performed on RNA extracts. The transplanted hearts were analyzed both during acute rejection up to 6 days and during chronic rejection up to 6 mo after transplantation and compared with normal controls. The animals of the chronic rejection group received cyclosporin A for immunosuppression. The TGF-beta bioactivity dramatically increased in the transplanted allografts during the chronic rejection process compared to the normal hearts, and so did the immunostaining as well as the mRNA levels for TGF-beta 1 and, to a lesser extent, the immunostaining for TGF-beta 2. TGF-beta 3 expression remained unchanged and was only found in the myocardium in trace amounts. During the acute rejection process up to 6 days after transplantation, TGF-beta immunoreactivity increased only slightly, whereas the TGF-beta mRNA was severalfold increased. Control animals treated with cyclosporin A showed a similar pattern at day 6 with regard to TGF-beta expression. LTBP was induced simultaneously with TGF-beta 1 and occurred within interstitial spaces of the myocardium. The TGF-beta was produced by macrophage-like infiltrating lymphocytes. In conclusion, highly elevated levels of TGF-beta and LTBP were found during chronic rejection of cardiac allografts in rats. The induction of TGF-beta may counteract the rejection process and could be useful for new therapeutic approaches in the prevention of allograft rejection.

Induction of transforming growth factor-beta during cardiac allograft rejection

The polypeptides of the transforming growth factor-beta (TGF-beta) family are potent endogenous immuno-regulators. Using a rat cardiac allograft transplant model, we investigated the expression of the precursor forms of TGF-beta 1, TGF-beta 2, and TGF-beta 3 and the latent TGF-beta binding protein (LTBP) by immunohistochemistry. The activity of TGF-beta in the extracts from transplanted as well as normal hearts was measured using a bioassay, and Northern blot analysis was performed on RNA extracts. The transplanted hearts were analyzed both during acute rejection up to 6 days and during chronic rejection up to 6 mo after transplantation and compared with normal controls. The animals of the chronic rejection group received cyclosporin A for immunosuppression. The TGF-beta bioactivity dramatically increased in the transplanted allografts during the chronic rejection process compared to the normal hearts, and so did the immunostaining as well as the mRNA levels for TGF-beta 1 and, to a lesser extent, the immunostaining for TGF-beta 2. TGF-beta 3 expression remained unchanged and was only found in the myocardium in trace amounts. During the acute rejection process up to 6 days after transplantation, TGF-beta immunoreactivity increased only slightly, whereas the TGF-beta mRNA was severalfold increased. Control animals treated with cyclosporin A showed a similar pattern at day 6 with regard to TGF-beta expression. LTBP was induced simultaneously with TGF-beta 1 and occurred within interstitial spaces of the myocardium. The TGF-beta was produced by macrophage-like infiltrating lymphocytes. In conclusion, highly elevated levels of TGF-beta and LTBP were found during chronic rejection of cardiac allografts in rats. The induction of TGF-beta may counteract the rejection process and could be useful for new therapeutic approaches in the prevention of allograft rejection.

Enhancement of the effect of low-dose cyclosporin A by sulphasalazine in prevention of cardiac allograft rejection in the rat

Sulphasalazine (SASP) is an immunomodulatory compound with disease-modifying activity in ulcerative colitis and in other autoimmune disorders. SASP was previously shown to prolong the survival of heart allografts in rats treated with cyclosporin A (CyA) for 9 days after transplantation. We have now evaluated whether SASP also exerts a beneficial effect under continuous treatment with CyA, when CyA is discontinued after 14 days, or alone if given 10 days prior to transplantation. Cardiac grafts were transplanted from PVG donors to Wistar/Kyoto recipients using an accessory cervical heart transplantation technique. Rejection was defined as the absence of palpable contractions and occurred in the control group in a very reproducible manner on day 8 or 9. SASP alone was given orally (100 mg/kg body weight) starting 10 days before transplantation and resulted in a minor prolongation of graft survival. When SASP was given in addition to oral CyA (1 mg/kg or 2 mg/kg from day 0 to rejection) there was a significant prolongation in graft survival [from medians of 8 (range 6-11) and 9 (range 8-11) days, respectively, to medians of 10 (range 8-15) and 12 (range 11-15) days, respectively]. When SASP was given from day 0 to rejection, in addition to a schedule of oral CyA (10 mg/kg) for 15 days, there was no prolongation of graft survival [median of 30 (range 26-42) days vs median of 32 (26-38) days]. The data show that SASP acts as a weak immunosuppressive agent which enhances the effect of CyA given at a low dose.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of LS-2616 on the graft protection achieved by cyclosporin A, prednisolone, and 15-deoxyspergualin in heart-transplanted rats

The immunostimulator LS-2616 abolishes the effect of cyclosporin A in a rat cardiac transplantation model. The present paper compares the characteristics of rejection obtained under different immunosuppressive regimens with and without additional LS-2616 application in the same model. Cyclosporin A (CyA, 10 mg/kg daily), prednisolone (15 mg/kg daily), or 15-deoxyspergualin (2, 5, or 10 mg/kg daily), all given from the day of transplantation until day 9, protected the grafts during the treatment period. The addition of LS-2616 (160 mg/kg, day -1 until stop) resulted in a total abrogation of the immunosuppressive effect of CyA and prednisolone. However, LS-2616 could only partially or not at all reverse the effect of 15-deoxyspergualine. These results show a certain drug selectivity of LS-2616 in promoting rejection of immunosuppressed allografts. Further studies with LS-2616 may be of benefit in evaluating the mode of action of different immunosuppressive compounds and, thus, contribute to finding more effective antirejection therapies.

Effects of prostaglandin E2 (PGE2) and drugs affecting PGE2 degradation on acute rejection of rat cardiac allografts

Systemic administration of prostaglandin E2 (PgE2) has been reported to prolong graft survival of heart transplants. We investigated the influence of systemic injection of two compounds which inhibit the endogenous degradation of PgE2 (CL42A and CL68A) and of local infusion of PgE2 into the transplant on the survival time of rat cardiac allografts. Both CL42A and CL68A gave increased graft survival time in two rat strain combinations, though this was not predictable in individual rats. Locally infused PgE2 gave slight, but not significant prolongation of graft survival in some recipients. Combined PgE2 and cyclosporin A, however, gave significant prolongation of graft survival time compared with cyclosporin A treatment alone. When local PgE2 treatment was begun 5 days after transplantation, graft survival time was prolonged in almost all the rats. Manipulation of the local PgE2 concentration thus seemed to have a positive effect on graft survival, possibly due to down-regulation of certain cells of the immune system by PgE2.

Expression of an interferon-gamma-like substance in normal and transplanted rat heart tissue

The presence of interferon-gamma-like molecules has been reported not only in lymphocytes, but also in certain nerve cells and in normal skeletal muscle. We have studied the reactivity of the anti-interferon-gamma monoclonal antibody DB1 with frozen sections of normal and transplanted rat hearts. Cardiac grafts from PVG donor rats were transplanted to syngeneic PVG recipients or allogeneic Wistar/Kyoto recipient rats with the use of an accessory cervical heart transplantation technique. The allogeneic heart transplants were harvested 4 days and the syngeneic grafts 4 weeks after transplantation. In normal hearts there was a weak but distinct reactivity with the anti-interferon-gamma antibody in most muscle cells. In addition, some lymphocytes and the Purkinje fibers were positive. Hearts transplanted over an allogeneic barrier revealed that staining for interferon-gamma on muscle cells was substantially increased whereas no or only a moderate increase in the anti-interferon-gamma staining was seen in hearts transplanted to syngeneic recipients. These data indicate that interferon-gamma present in rat myocyte may be involved in the pathophysiology of graft rejection and also suggest that interferon-gamma may be of importance for the function of normal rat heart muscle cells.

Evidence that LS-2616 (linomide) causes acute rejection of rat allografts protected by cyclosporine but not of long-term surviving allografts

The immunomodulator LS-2616 (Linomide) induces rejection of cyclosporine-protected rat cardiac allografts. The aim of this study was to characterize this rejection in the presence of CsA and to test LS-2616 in other models of permanent graft acceptance in the rat. PVG rat hearts were transplanted heterotopically to Wistar/Kyoto (Wi/Ky) rat recipients on day 0. The recipients were treated orally on days 0-9 with CsA (10-40 mg/kg) and/or with LS-2616 (2.5-160 mg/kg) starting at different times (day -7 -+5) until the day of complete rejection. The addition of LS-2616 (day -1--stop) to CsA (10 mg/kg) resulted in a dose-dependent antagonism of the immunosuppressive effect of CsA with daily doses of 2.5-160 mg/kg. Furthermore, the results were similar, irrespective of whether LS-2616 treatment (160 mg/kg) was started on day -7, -1, +1, +3, or +5. LS-2616 (160 mg/kg) pretreatment of the recipient for 7 days before transplantation was considerably less effective. CsA (20 mg/kg) for 14 days after a PVG to DA transplantation resulted in permanent graft survival. This was not abrogated by LS-2616. Neither was rejection induced in long-term surviving grafts of RT1.C incompatible Lewis recipients. Our data suggest that LS-2616 activates already stimulated and sensitized T cells that are otherwise controlled by CsA.

Cytokine gene expression: analysis using northern blotting, polymerase chain reaction and in situ hybridization

We describe here the use of northern blotting, PCR and in situ hybridization for the analysis of cytokine gene expression. These techniques, each with their advantages and disadvantages, have been used to monitor cytokine gene expression in sites of immune reactivity and in the developing thymus. Whilst expression of a gene usually correlates well with protein production from that gene, this may not always be the case. The development of methods to analyze protein production in situ, for instance by immunohistochemistry, together with analysis of mRNA expression will allow us to begin to understand the role of cytokines within the immune system of the intact animal.