Variation In Collagen Content Research Articles

Circulating and Magnetic Resonance Imaging Biomarkers of Intestinal Fibrosis in Small Bowel Crohn's Disease.

We previously identified circulating and MRI biomarkers associated with the surgical management of Crohn's disease (CD). Here we tested associations between these biomarkers and ileal resection inflammation and collagen content. Fifty CD patients undergoing ileal resection were prospectively enrolled at 4 centers. Circulating CD64, extracellular matrix protein 1 (ECM1), GM-CSF autoantibodies (GM-CSF Ab), and fecal calprotectin were measured by ELISA. Ileal 3-dimensional magnetization transfer ratio (3D MTR), modified Look-Locker inversion recovery (MOLLI) T1 relaxation, diffusion-weighted intravoxel incoherent motion (IVIM), and the simplified magnetic resonance index of activity (sMaRIA) were measured by MRI. Ileal resection specimen acute inflammation was graded, and collagen content was measured quantitatively using second harmonic imaging microscopy. Associations between biomarkers and ileal collagen content were tested. Median (interquartile range [IQR]) age was 19.5 (16-33) years. We observed an inverse relationship between ileal acute inflammation and collagen content (r = -0.39 [95% confidence interval {CI}: -0.61, -0.10], P = .008). Most patients (33 [66%]) received biologics, with no variation in collagen content with treatment exposures. In the univariate analysis, CD64, GM-CSF Ab, fecal calprotectin, and sMaRIA were positively associated with acute inflammation and negatively associated with collagen content (P < .1). The multivariable model for ileal collagen content (R2 = 0.31 [95% CI: 0.11, 0.52]) included log CD64 (β = -.27; P = .19), log ECM1 (β = .47; P = .06), log GM-CSF Ab (β = -.15; P = .01), IVIM f (β = .29, P = .10), and IVIM D* (β = 1.69, P = .13). Clinically available and exploratory circulating and MRI biomarkers are associated with the degree of inflammation versus fibrosis in CD ileal resections. With further validation, these biomarkers may be used to guide medical and surgical decision-making for refractory CD.

Evaluation of Extracellular Matrix Composition to Improve Breast Cancer Modeling.

The development of resistance to therapy is a significant obstacle to effective therapeutic regimens. Evaluating the effects of oncology drugs in the laboratory setting is limited by the lack of translational models that accurately recapitulate cell-microenvironment interactions present in tumors. Acquisition of resistance to therapy is facilitated, in part, by the composition of the tumor extracellular matrix (ECM), with the primary current in vitro model using collagen I (COL I). Here we seek to identify the prevalence of COL I-enhanced expression in the triple-negative breast cancer (TNBC) subtype. Furthermore, we identify if methods of response to therapy are altered depending on matrix composition. We demonstrated that collagen content varies in patient tumor samples across subtypes, with COL I expression dramatically increased in typically less aggressive estrogen receptor (ER)-positive(ER+)/progesterone receptor (PGR)-positive (PGR+) cancers irrespective of patient age or race. These findings are of significance considering how frequently COL I is implicated in tumor progression. In vitro analyses of ER+ and ER-negative (ER-) cell lines were used to determine the effects of ECM content (collagen I, collagen IV, fibronectin, and laminin) on proliferation, cellular phenotype, and survival. Neither ER+ nor ER- cells demonstrated significant increases in proliferation when cultured on these ECM substrates. ER- cells cultured on these substrates were sensitized to both chemotherapy and targeted therapy. In addition, MDA-MB-231 cells expressed different morphologies, binding affinities, and stiffness across these substrates. We also demonstrated that ECM composition significantly alters transcription of senescence-associated pathways across ER+ and ER- cell lines. Together, these results suggest that complex matrix composites should be incorporated into in vitro tumor models, especially for the drug-resistant TNBC subtype. Impact statement The importance of tumor extracellular matrix (ECM) in disease progression is often inadequately represented in models of breast cancer that rely heavily on collagen I and Matrigel. Through immunohistochemistry analysis of patient breast tumors, we show a wide variation in collagen content based on subtype, specifically a repression of fibril collagens in the receptor negative subtype, irrespective of age and race. We also demonstrated that tumor ECM composition alters cellular elasticity and oncogenic pathway activation demonstrating that physiologically relevant three-dimensional models of breast cancer should include an ECM that is subtype specific.

Photoacoustic imaging of kidney fibrosis for assessing pretransplant organ quality.

Roughly 10% of the world's population has chronic kidney disease (CKD). In its advanced stages, CKD greatly increases the risk of hospitalization and death. Although kidney transplantation has revolutionized the care of advanced CKD, clinicians have limited ways of assessing donor kidney quality. Thus, optimal donor kidney-recipient matching cannot be performed, meaning that some patients receive damaged kidneys that function poorly. Fibrosis is a form of chronic damage often present in donor kidneys, and it is an important predictor of future renal function. Currently, no safe, easy-to-perform technique exists that accurately quantifies renal fibrosis. We describe a potentially novel photoacoustic (PA) imaging technique that directly images collagen, the principal component of fibrotic tissue. PA imaging noninvasively quantifies whole kidney fibrotic burden in mice, and cortical fibrosis in pig and human kidneys, with outstanding accuracy and speed. Remarkably, 3-dimensional PA imaging exhibited sufficiently high resolution to capture intrarenal variations in collagen content. We further show that PA imaging can be performed in a setting that mimics human kidney transplantation, suggesting the potential for rapid clinical translation. Taken together, our data suggest that PA collagen imaging is a major advance in fibrosis quantification that could have widespread preclinical and clinical impact.

An ultrastructural and biochemical analysis of collagen in rat peripheral nerves: the relationship between fibril diameter and mechanical properties

Mechanical features are distributed heterogeneously within nerve tissue, with compliance increased at articulations. This study explored whether differences in stiffness between joint regions (JRs) and non-joint regions (NJRs) of rat median and sciatic nerves were related to localised variation in collagen content or fibril diameter. There was no significant difference in the amount of collagen detected by biochemical assay in JRs and NJRs of either nerve. Ultrastructural analysis showed collagen fibril diameter ranges of 20-80 nm in the endoneurium and perineurium and 30-130 nm in the epineurium. In the median nerve, but not the sciatic nerve, there were significantly smaller fibrils in JRs compared to NJRs. This corresponded to a greater number density of fibrils in JRs compared to NJRs in the epineurium and endoneurium of the median nerve. We report the presence therefore of a population of thinner collagen fibrils in the JR of the median nerve that corresponds to the location of increased compliance in this tissue, suggesting that localised variation in collagen fibril diameter contributes to the longitudinal heterogeneity of tensile properties in this nerve.

Variations in collagen content of asynergic left ventricular segments in explanted hearts of men with ischemic cardiomyopathy

Transmural left ventricular (LV) biopsies obtained at the time of coronary artery surgery have been used to evaluate the histomorphologic features of viable myocardium in patients with ischemic cardiomyopathy. 1–16 Usually, 1 or 2 biopsies are obtained from the center of the LV region supplied by the left anterior descending coronary artery. The biopsy specimens (1.2 to 1.5 mm in diameter) are subsequently used for quantifi cation of collagen using grids with visual point counting. 1–16 The degree of myocardial fi brosis in these biopsy samples has been correlated with the results of various noninvasive tests used for assessment of preoperative regional myocardial viability. However, it is unclear whether the data obtained from these transmural biopsy samples would uniformly refl ect the overall histomorphologic features of the entire LV region as evaluated by noninvasive imaging techniques. In this study, we determined the extent of variation in volume fraction of collagen of 2-mm-wide (biopsy-equivalent) consecutive transmural sections of mid-LV anterior wall from explanted hearts of men with chronic ischemic heart disease. Moreover, we examined the variability of fi brosis in normal, ischemic, and scarred myocardium as assessed by thallium.  The 13 men with ischemic cardiomyopathy awaiting cardiac transplantation were prospectively enrolled in a study determining the relation of thallium uptake to myocardial fi brosis. 17 Patients’ ages ranged from 41 to 62 years (mean 54). All patients had severe (New York Heart Association functional class III to IV) heart failure and/or angina pectoris and multivessel coronary artery disease, and were listed as stable outpatients at the time of enrollment. Patients with recent acute myocardial infarction or unstable angina were excluded from the study. Cardiac transplantation was performed at a mean of 6 2 months after the nuclear imaging studies. The explanted hearts were fi rst fi xed in formaldehyde. The left ventricle was then sliced transversely at a mean thickness of 8 mm/slice from apex to base. A mid-LV slice was divided into 8 large segments. The 2 large segments representing the anterior wall were then embedded in paraffi n, cut at a thickness of 5 m and stained with picrosirius red. These segments were further divided into consecutive 2-mmwide transmural sections. Percent collagen was then quantifi ed using a computerized image analysis system (Quantimet 520, Cambridge, Massachusetts) in the large segments and in each small section, as previously described. 18 All patients underwent stress-redistribution-reinjection thallium single-photon emission computed tomography. Short-axis tomograms at the mid left ventricle, corresponding to that used for the histomorphologic study, from the 3 sets of thallium images (stress, redistribution, and reinjection) were analyzed objectively, using a semiautomated quantitative circumferential profi le as previously described. 19 Briefl y, for each patient, an operator-defi ned region of interest was drawn around the LV activity of each short-axis slice on the corresponding stress, redistribution, and reinjection images. As with the histologic assessment, the myocardial activity was divided into 8 segments of equal arcs, beginning at the center of the anterior LV wall and proceeding clockwise. Mean counts per pixel within the 2 anterior wall segments (anteroseptal and anterolateral) on stress, redistribution, and reinjection images were computed. The myocardial segment with the highest thallium activity on the stress tomogram was used as the normal reference segment. The same segment in redistribution and reinjection thallium

Estimation of total collagen and types I and III collagen in canine rotator cuff tendons.

The collagen composition of the supraspinatus, infraspinatus, and subscapularis tendons, which form part of the rotator cuff of the shoulder, was determined. Tendons were obtained from adult, male beagle dogs and total collagen was estimated by measurement of hydroxyproline. There was little variation in collagen content among the three major cuff tendons and the quantity approximated that cited in the literature for other tendons. However, the collagen content in the insertion zone of the supraspinatus tendon was significantly higher than in the tendon proper. NaCl fractionation of supraspinatus collagen indicated that type I was the predominant collagen but significant amounts of type III and possibly some type II and type V were also present. Interestingly, there appeared to be more type III collagen in the insertion zone than in the tendon proper, cyanogen bromide digestion and peptide mapping confirmed this finding. The differential collagen composition of the supraspinatus tendon may contribute to the high incidence of tear that is associated with this rotator cuff tendon.

A comparative infrared spectroscopic study of human breast tumors and breast tumor cell xenografts

AbstractFourier transform infrared spectroscopy has been applied to the study of human breast tumors, human breast tumor cell lines and xenografted human tumor cells. The results presented indicate that substantial differences exist on a macroscopic level between human tumors, xenografted tumors and human tumor cell lines, which are related to the presence of a significant connective tissue matrix in the tumors. On a macroscopic level tumor cell xenografts appear, in spectroscopic terms, to be relatively homogeneous with a relatively weak signature characteristic of connective tissue. Differences on a microscopic level between adjacent small (30 μm2) areas of the same xenografted tumor could be detected, which were due to local variations in collagen content. In addition to variations in collagen content, variation in the deposition of microscopic fat droplets throughout both human and xenografted tumors could be detected. These results indicate the care with which infrared spectroscopic studies of tissues must be carried out to avoid incorrect interpretation of results due to an incomplete understanding of tissue pathology. © 1995 John Wiley &amp; Sons, Inc.

Segmental variation in microstructure, matrix synthesis and cell proliferation in rabbit flexor tendon.

An experimental culture system was designed with the purpose of studying matrix synthesis and cell proliferation in the deep flexor tendon of the rabbit forepaw. Special attention was paid to differences between three consecutive defined segments of the tendon from the region of the tendon sheath. There were two fibrocartilaginous areas in the tendon, one in the dorsal part of the proximal segment and one in the volar part of the distal segment. The intermediate segment consisted of regular tendinous tissue. The dorsal aspect of the distal segment was further characterized by a cell rich area related to the entrance of the vinculum longum. Proteoglycan synthesis in vitro was higher in the proximal and distal segments than in the intermediate, while collagen synthesis was highest in the intermediate tendinous segment. Variations in collagen content were reflected in variations in collagen synthesis. The rate of cell proliferation was highest in the intermediate segment. Segmental biochemical characteristics correlated well with morphological variations of the deep flexor tendon. These variations may reflect an adaptation to different mechanical forces acting on the tendon. The segmental variations may also be relevant for the healing capacity of the flexor tendon.

Collagen concentration and rates of synthesis in idiopathic pulmonary fibrosis.

To define the biochemical correlates of the apparent morphologic increase in lung interstitial collagen in idiopathic pulmonary fibrosis (IPF), collagen content was quantitated, and the morphologic degree of fibrosis was assessed in 9 patients with IPF and 6 control subjects. There were no significant differences in the collagen content among patients with IPF compared with that of control subjects. In addition, there was no correlation between collagen content and the morphologic assessment of the degree of fibrosis. Analysis of the collagen content from multiple sites made from base to apex of postmortem material from 3 patients with IPF and 2 control subjects demonstrated a wide, but similar, variation in collagen content in both groups; no definite pattern of anatomic distribution was found in either the patients with IPF or the control subjects. Furthermore, the rates of collagen and noncollagen protein synthesis in explants of lung of patients with IPF demonstrated no significant differences compared with those of the control subjects. The results of this study are consistent with the concept that IPF is a disease of an alteration in quality, form, and location of collagen rather than simply a disease of increased interstitial collagen.

Application de la chromatographie en phase gazeuse à la mesure de la proline et de l'hydroxyproline incorporées au cours de la biosynthèse du collagène

In this paper, gas—liquid chromatography, adapted for the determination of collagen amino acids, is described. This technique was attractive for its sensitivity in that only a small amount of protein such as in 0.5 mg of tissue, especially as obtained from biopsy tissue, was needed for the separation and determination of proline (Pro), 4-hydroxyproline (4-Hyp), 3-hydroxyproline (3-Hyp), lysine (Lys), hydroxylysine (Hyl) and ϵ-hydroxynorleucine (ϵ-OH-Norleu), the characteristic amino acids of collagen. Thus, without purification of collagen, by determining the ratio Hyl/4-Hyp and 4-Hyp/Pro it was possible to determine some anomalies in the collagen content of biopsy tissue (skin or liver). The ratio Hyl/4-Hyp allows an estimation of the lack of hydroxylation of polypeptidic lysine as in the Ehlers-Danlos syndrome type VI; and the ratio 4-Hyp/Pro allows measurement of variations in collagen content in relation to protein, especially in the liver, as in alcoholic cirrhosis.