Association between adjuvant therapy and survival in colorectal cancer patients according to metabolic Warburg-subtypes

PURPOSE

Tumor location and tumor node metastasis (TNM) stage guide treatment decisions in colorectal cancer (CRC) patients. However, patients with the same disease stage do not benefit equally from adjuvant therapy. Hence, there remains an urgent clinical need to identify prognostic and/or predictive biomarker(s) to personalize treatment decisions. In this exploratory study, we investigated whether our previously defined metabolic Warburg-subtypes can predict which CRC patients might derive survival benefit from adjuvant therapy.

METHODS

Information regarding treatment (surgery only: n = 1451; adjuvant radiotherapy: n = 82; or adjuvant chemotherapy: n = 260) and Warburg-subtype (Warburg-low: n = 485, -moderate: n = 641, or -high: n = 667) was available for 1793 CRC patients from the Netherlands Cohort Study (NLCS). Kaplan-Meier curves and Cox regression models were used to investigate survival benefit from adjuvant therapy compared to surgery-only for the different Warburg-subtypes.

RESULTS

Patients with Warburg-moderate CRC (HRCRC-specific 0.64; 95% CI 0.47-0.86, HRoverall 0.61; 95% CI 0.47-0.80), and possibly Warburg-high CRC (HRCRC-specific 0.86; 95% CI 0.65-1.14, HRoverall 0.82; 95% CI 0.64-1.05), had survival benefit from adjuvant therapy. No survival benefit was observed for patients with Warburg-low CRC (HRCRC-specific 1.07; 95% CI 0.76-1.52, HRoverall 0.95; 95% CI 0.70-1.30). There was a significant interaction between Warburg-subtype and adjuvant therapy for CRC-specific survival (p = 0.049) and overall survival (p = 0.035).

CONCLUSION

Our results suggest that Warburg-subtypes may predict survival benefit from adjuvant therapy in CRC patients. A survival benefit from adjuvant therapy was observed for patients with Warburg-moderate and possibly Warburg-high CRC, but not for patients with Warburg-low CRC. Future prospective studies are necessary to validate our findings.

Tumour infiltrating lymphocytes and survival after adjuvant chemotherapy in patients with gastric cancer: post-hoc analysis of the CLASSIC trial

BACKGROUND

Only a subset of gastric cancer (GC) patients with stage II-III benefits from chemotherapy after surgery. Tumour infiltrating lymphocytes per area (TIL density) has been suggested as a potential predictive biomarker of chemotherapy benefit.

METHODS

We quantified TIL density in digital images of haematoxylin-eosin (HE) stained tissue using deep learning in 307 GC patients of the Yonsei Cancer Center (YCC) (193 surgery+adjuvant chemotherapy [S + C], 114 surgery alone [S]) and 629 CLASSIC trial GC patients (325 S + C and 304 S). The relationship between TIL density, disease-free survival (DFS) and clinicopathological variables was analysed.

RESULTS

YCC S patients and CLASSIC S patients with high TIL density had longer DFS than S patients with low TIL density (P = 0.007 and P = 0.013, respectively). Furthermore, CLASSIC patients with low TIL density had longer DFS if treated with S + C compared to S (P = 0.003). No significant relationship of TIL density with other clinicopathological variables was found.

CONCLUSION

This is the first study to suggest TIL density automatically quantified in routine HE stained tissue sections as a novel, clinically useful biomarker to identify stage II-III GC patients deriving benefit from adjuvant chemotherapy. Validation of our results in a prospective study is warranted.

Relationship between the Warburg effect in tumour cells and the tumour microenvironment in colorectal cancer patients: Results from a large multicentre study

Colorectal cancer (CRC) remains one of the most prevalent and deadly cancers worldwide. The tumour-node-metastasis stage (TNM) is currently the most clinically important tool to predict prognosis for CRC patients. However, patients with the same TNM stage can have different prognoses. The metabolic status of tumour cells (Warburg-subtype) has been proposed as potential prognostic factor in CRC. However, potential biological mechanisms underlying the relationship between Warburg-subtype and prognosis have not been investigated in detail. One potential mechanism could be that the metabolic status of tumour cells affects the tumour microenvironment (TME). Our objective was to investigate the relationship between Warburg-subtypes and the TME. Haematoxylin/Eosin stained tumour tissue microarray cores from 2171 CRC patients from the Netherlands Cohort Study were semi quantitatively assessed for tumour infiltrating lymphocytes (TILs) and relative tumour stroma content. 5745 cores were assessed by putting each core in one of four categories for both TILs and stroma. The relationship between Warburg-subtype, TILs, and tumour stroma content was investigated. The frequency of CRC in the different TIL categories was (n, %): very low (2538, 44.2), low (2463, 42.9), high (722, 12.6), and very high (22, 0.4). The frequency of CRC in the different tumour stroma content categories was: ≤ 25% (2755, 47.9), > 25% ≤ 50% (1553, 27) > 50% ≤ 75% (905, 15.8), and > 75% (532, 9.3). There was neither an association between Warburg-subtype and tumour stroma content (p = 0.229) nor between Warburg-subtype and TILs (p = 0.429). This is the first study to investigate the relationship between Warburg-subtypes and the TME in a large population-based series of CRC patients. Our data suggest that the prognostic value of Warburg-subtypes cannot be directly attributed to differences in TILs or tumour stroma content. Our results require confirmation in an independent series.

Energy balance-related factors in childhood and adolescence and risk of colorectal cancer based on KRAS, PIK3CA, and BRAF mutations and MMR status

KRAS mutations (KRAS_mut ), PIK3CA_mut , BRAF_mut , and deficient DNA mismatch repair (dMMR) have been associated with the Warburg effect. We previously reported differential associations between early-life energy balance-related factors (height, energy restriction, body mass index [BMI]) and colorectal cancer (CRC) subtypes based on the Warburg effect. We now investigated associations of early-life energy balance-related factors and the risk of CRC subgroups based on mutation and MMR status. Data from the Netherlands Cohort Study was used. KRAS_mut , PIK3CA_mut, BRAF_mut, and MMR status were available for 2349 CRC cases, and complete covariate data for 1934 cases and 3911 subcohort members. Multivariable-adjusted Cox regression was used to estimate associations of height, energy restriction proxies (exposure to Dutch Hunger Winter, Second World War, Economic Depression), and early adult BMI (age 20 years) with risk of CRC based on individual molecular features and combinations thereof (all-wild-type+MMR-proficient [pMMR]; any-mutation/dMMR). Height was positively associated with any-mutation/dMMR CRC but not all-wild-type+pMMR CRC, with the exception of rectal cancer in men, and with heterogeneity in associations observed for colon cancer in men (p-heterogeneity = 0.049) and rectal cancer in women (p-heterogeneity = 0.014). Results on early-life energy restriction proxies in relation to the risk of CRC subgroups did not show clear patterns. Early adult BMI was positively, but not significantly, associated with KRAS_mut colon cancer in men and with BRAF_mut and dMMR colon cancer in women. Our results suggest a role of KRAS_mut , PIK3CA_mut , BRAF_mut , and dMMR in the etiological pathway between height and CRC risk. KRAS_mut might potentially play a role in associations of early adult BMI with colon cancer risk in men, and BRAF_mut and dMMR in women.

Association between mutational subgroups, Warburg-subtypes, and survival in patients with colorectal cancer

BACKGROUND

Previous research suggests that Warburg-subtypes are related to potentially important survival differences in colorectal cancer (CRC) patients. In the present study, we investigated whether mutational subgroups based on somatic mutations in RAS, BRAF, PIK3CA, and MET, which are known to promote the Warburg-effect, as well as mismatch repair (MMR) status, hold prognostic value in CRC. In addition, we investigated whether Warburg-subtypes provide additional prognostic information, independent of known prognostic factors like TNM stage.

METHODS

CRC patients (n = 2344) from the prospective Netherlands Cohort Study (NLCS) were classified into eight mutually exclusive mutational subgroups, based on observed mutations in RAS, BRAF, PIK3CA, and MET, and MMR status: All-wild-type + MMR_proficient , KRAS_mut  + MMR_proficient , KRAS_mut  + PIK3CA_mut  + MMR_proficient , PIK3CA_mut  + MMR_proficient , BRAF_mut  + MMR_proficient , BRAF_mut  + MMR_deficient , other + MMR_proficient , and other + MMR_deficient . Kaplan-Meier curves and Cox regression models were used to investigate associations between mutational subgroups and survival, as well as associations between our previously established Warburg-subtypes and survival within these mutational subgroups.

RESULTS

Compared to patients with all-wild-type + MMR_proficient CRC, patients with KRAS_mut  + MMR_proficient , KRAS_mut  + PIK3CA_mut  + MMR_proficient , BRAF_mut  + MMR_proficient , or other + MMR_proficient CRC had a statistically significant worse survival (HR_CRC-specific ranged from 1.29 to 1.88). In contrast, patients with other + MMR_deficient CRC had the most favorable survival (HR_CRC-specific 0.48). No statistically significant survival differences were observed for the Warburg-subtypes within mutational subgroups.

CONCLUSION

Our results highlight the prognostic potential of mutational subgroups in CRC. Warburg-subtypes did not provide additional prognostic information within these mutational subgroups. Future larger-scale prospective studies are necessary to validate our findings and to examine the potential clinical utility of CRC subtyping based on mutational subgroups.

Energy balance-related factors and risk of colorectal cancer based on KRAS, PIK3CA, and BRAF mutations and MMR status

Introduction

KRAS mutations (KRAS_mut), PIK3CA_mut, BRAF_mut, and mismatch repair deficiency (dMMR) have been associated with the Warburg-effect. We previously observed differential associations between energy balance-related factors (BMI, clothing-size, physical activity) and colorectal cancer (CRC) subtypes based on the Warburg-effect. We now investigated whether associations between energy balance-related factors and risk of CRC differ between subgroups based on mutation and MMR status.

Methods

Information on molecular features was available for 2349 incident CRC cases within the Netherlands Cohort Study (NLCS), with complete covariate data available for 1934 cases and 3911 subcohort members. Multivariable-adjusted Cox-regression was used to estimate associations of energy balance-related factors with risk of CRC based on individual molecular features (KRAS_mut; PIK3CA_mut; BRAF_mut; dMMR) and combinations thereof (all-wild-type + MMR-proficient (pMMR); any-mutation/dMMR).

Results

In men, BMI and clothing-size were positively associated with risk of colon, but not rectal cancer, regardless of molecular features subgroups; the strongest associations were observed for PIK3CA_mut colon cancer. In women, however, BMI and clothing-size were only associated with risk of KRAS_mut colon cancer (p-heterogeneity_{KRASmut versus all-wild-type+pMMR} = 0.008). Inverse associations of non-occupational physical activity with risk of colon cancer were strongest for any-mutation/dMMR tumors in men and women, and specifically for PIK3CA_mut tumors in women. Occupational physical activity was inversely associated with both combination subgroups of colon cancer in men.

Conclusion

In men, associations did not vary according to molecular features. In women, a role of KRAS mutations in the etiological pathway between adiposity and colon cancer is suggested, and of PIK3CA mutations between physical activity and colon cancer.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00432-022-04019-9.

Energy balance‐related factors in childhood and adolescence and risk of colorectal cancer expressing different levels of proteins involved in the Warburg‐effect

Early‐life (childhood to adolescence) energy balance‐related factors (height, energy restriction, BMI) have been associated with adult colorectal cancer (CRC) risk. Warburg‐effect activation via PI3K/Akt‐signaling might explain this link. We investigated whether early‐life energy balance‐related factors were associated with risk of Warburg‐subtypes in CRC. We used immunohistochemistry for six proteins involved in the Warburg‐effect (LDHA, GLUT1, MCT4, PKM2, P53, and PTEN) on tissue microarrays of 2399 incident CRC cases from the prospective Netherlands Cohort Study (NLCS). Expression levels of all proteins were combined into a pathway‐based sum score and categorized into three Warburg‐subtypes (Warburg‐low/‐moderate/‐high). Multivariable Cox‐regression analyses were used to estimate associations of height, energy restriction proxies (exposure to Dutch Hunger Winter; Second World War [WWII]; Economic Depression) and adolescent BMI with Warburg‐subtypes in CRC. Height was positively associated with colon cancer in men, regardless of Warburg‐subtypes, and with Warburg‐low colon and Warburg‐moderate rectal cancer in women. Energy restriction during the Dutch Hunger Winter was inversely associated with colon cancer in men, regardless of Warburg‐subtypes. In women, energy restriction during the Hunger Winter and WWII was inversely associated with Warburg‐low colon cancer, whereas energy restriction during the Economic Depression was positively associated with Warburg‐high colon cancer. Adolescent BMI was positively associated with Warburg‐high colon cancer in men, and Warburg‐moderate rectal cancer in women. In conclusion, the Warburg‐effect seems to be involved in associations of adolescent BMI with colon cancer in men, and of energy restriction during the Economic Depression with colon cancer in women. Further research is needed to validate these results.

Expression of proteins associated with the Warburg-effect and survival in colorectal cancer

Previous research has suggested that the expression of proteins related to the Warburg effect may have prognostic value in colorectal cancer (CRC), but results remain inconsistent. Our objective was to investigate the relationship between Warburg-subtypes and patient survival in a large population-based series of CRC patients. In the present study, we investigated the expression of six proteins related to the Warburg effect (LDHA, GLUT1, MCT4, PKM2, p53, PTEN) by immunohistochemistry on tissue microarrays (TMAs) from 2,399 incident CRC patients from the prospective Netherlands Cohort Study. Expression levels of the six proteins were combined into a pathway-based sum-score and patients were categorised into three Warburg-subtypes (low/moderate/high). The associations between Warburg-subtypes and CRC-specific and overall survival were investigated using Kaplan-Meier curves and Cox regression models. CRC patients were classified as Warburg-low (n = 695, 29.0%), Warburg-moderate (n = 858, 35.8%) or Warburg-high (n = 841, 35.1%). Patients with Warburg-high CRC had the poorest CRC-specific [hazard ratio (HR) 1.17; 95% CI 1.00-1.38] and overall survival (HR 1.19; 95% CI 1.05-1.35), independent of known prognostic factors. In stratified analyses, this was particularly true for patients with tumour-node-metastasis (TNM) stage III CRC (HR_CRC-specific 1.45; 95% CI 1.10-1.92 and HR_overall 1.47; 95% CI 1.15-1.87), and cancers located in the rectum (HR_overall 1.56; 95% CI 1.15-2.13). To our knowledge, this is the first study to identify the prognostic value of immunohistochemistry-based Warburg-subtypes in CRC. Our data suggest that Warburg-subtypes are related to potentially important differences in CRC survival. Further research is required to validate our findings and to investigate the potential clinical utility of these Warburg-subtypes in CRC.

Validity and Reproducibility of Immunohistochemical Scoring by Trained Non-Pathologists on Tissue Microarrays

BACKGROUND

Scoring of immunohistochemistry (IHC) staining is often done by non-pathologists, especially in large-scale tissue microarray (TMA)-based studies. Studies on the validity and reproducibility of scoring results from non-pathologists are limited. Therefore, our main aim was to assess interobserver agreement between trained non-pathologists and an experienced histopathologist for three IHC markers with different subcellular localization (nucleus/membrane/cytoplasm).

METHODS

Three non-pathologists were trained in recognizing adenocarcinoma and IHC scoring by a senior histopathologist. Kappa statistics were used to analyze interobserver and intraobserver agreement for 6,249 TMA cores from a colorectal cancer series.

RESULTS

Interobserver agreement between non-pathologists (independently scored) and the histopathologist was "substantial" for nuclear and membranous IHC markers (κ_range = 0.67-0.75 and κ_range = 0.61-0.69, respectively), and "moderate" for the cytoplasmic IHC marker (κ_range = 0.43-0.57). Scores of the three non-pathologists were also combined into a "combination score" (if at least two non-pathologists independently assigned the same score to a core, this was the combination score). This increased agreement with the pathologist (κ_nuclear = 0.74; κ_membranous = 0.73; κ_cytopasmic = 0.57). Interobserver agreement between non-pathologists was "substantial" (κ_nuclear = 0.78; κ_membranous = 0.72; κ_cytopasmic = 0.61). Intraobserver agreement of non-pathologists was "substantial" to "almost perfect" (κ_{nuclear,range} = 0.83-0.87; κ_{membranous,range} = 0.75-0.82; κ_cytopasmic = 0.69). Overall, agreement was lowest for the cytoplasmic IHC marker.

CONCLUSIONS

This study shows that adequately trained non-pathologists are able to generate reproducible IHC scoring results, that are similar to those of an experienced histopathologist. A combination score of at least two non-pathologists yielded optimal results.

IMPACT

Non-pathologists can generate reproducible IHC results after appropriate training, making analyses of large-scale molecular pathological epidemiology studies feasible within an acceptable time frame.

Abstract 830: Validity and reproducibility of immunohistochemical scoring by trained non-pathologists on Tissue MicroArrays

Aims: Scoring of immunohistochemical (IHC) staining is often done by non-pathologists, especially in large-scale Tissue MicroArray (TMA)-based studies. Studies on the validity of scoring results from non-pathologists are very limited. Therefore, our main aim was to assess inter-observer agreement between trained non-pathologists and an experienced histopathologist for three IHC markers with different subcellular localisation (nucleus/membrane/cytoplasm).

Methods and results: Three non-pathologists were trained in recognizing adenocarcinoma and IHC scoring by a senior histopathologist. Kappa statistics were used to analyse inter- and intra-observer agreement for 6249 TMA cores from a colorectal cancer (CRC) series. Inter-observer agreement between non-pathologists (independently scored) and the histopathologist was “substantial” for nuclear and membranous IHC markers (κrange=0.67-0.75 and κrange=0.61-0.69, respectively), and “moderate” for the cytoplasmic IHC marker (κrange=0.43-0.57). Scores of the three non-pathologists were also combined into a combination score (if at least two non-pathologists independently assigned the same score to a core, this was the combination score). This increased agreement with the pathologist (κnuclear=0.74; κmembranous=0.73; κcytopasmic=0.56). Inter-observer agreement between non-pathologists was “substantial” (κnuclear=0.78; κmembranous=0.72; κcytopasmic=0.61). Intra-observer agreement of non-pathologists was “substantial” to “almost perfect” (κnuclear,range=0.83-0.87; κmembranous,range=0.75-0.82; κcytopasmic,range=0.69-0.69). Overall, agreement was lowest for the cytoplasmic IHC marker.

Conclusions: This study shows that adequately trained non-pathologists are able to produce similar IHC scoring results as an experienced histopathologist. Considering the histopathologist's score as the golden standard, we can conclude that trained non-pathologists can produce valid IHC results on TMA sections. A combination score of at least two non-pathologists yielded optimal results.

Citation Format: Kelly Offermans, Josien C. Jenniskens, Iryna Samarska, Gregorio E. Fazzi, Colinda C. Simons, Kim M. Smits, Leo J. Schouten, Matty P. Weijenberg, Piet A. van den Brandt, Heike I. Grabsch. Validity and reproducibility of immunohistochemical scoring by trained non-pathologists on Tissue MicroArrays [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 830.

Integrative multiomics analysis of human atherosclerosis reveals a serum response factor-driven network associated with intraplaque hemorrhage

BACKGROUND

While single-omics analyses on human atherosclerotic plaque have been very useful to map stage- or disease-related differences in expression, they only partly capture the array of changes in this tissue and suffer from scale-intrinsic limitations. In order to better identify processes associated with intraplaque hemorrhage and plaque instability, we therefore combined multiple omics into an integrated model.

METHODS

In this study, we compared protein and gene makeup of low- versus high-risk atherosclerotic lesion segments from carotid endarterectomy patients, as judged from the absence or presence of intraplaque hemorrhage, respectively. Transcriptomic, proteomic, and peptidomic data of this plaque cohort were aggregated and analyzed by DIABLO, an integrative multivariate classification and feature selection method.

RESULTS

We identified a protein-gene associated multiomics model able to segregate stable, nonhemorrhaged from vulnerable, hemorrhaged lesions at high predictive performance (AUC >0.95). The dominant component of this model correlated with αSMA- PDGFRα+ fibroblast-like cell content (p = 2.4E-05) and Arg1+ macrophage content (p = 2.2E-04) and was driven by serum response factor (SRF), possibly in a megakaryoblastic leukemia-1/2 (MKL1/2) dependent manner. Gene set overrepresentation analysis on the selected key features of this model pointed to a clear cardiovascular disease signature, with overrepresentation of extracellular matrix synthesis and organization, focal adhesion, and cholesterol metabolism terms, suggestive of the model's relevance for the plaque vulnerability. Finally, we were able to corroborate the predictive power of the selected features in several independent mRNA and proteomic plaque cohorts.

CONCLUSIONS

In conclusion, our integrative omics study has identified an intraplaque hemorrhage-associated cardiovascular signature that provides excellent stratification of low- from high-risk carotid artery plaques in several independent cohorts. Further study revealed suppression of an SRF-regulated disease network, controlling lesion stability, in vulnerable plaque, which can serve as a scaffold for the design of targeted intervention in plaque destabilization.

Large negative lymph nodes - a surrogate for immune activation in rectal cancer patients?

AIM

The size of regional, tumor draining lymph nodes without metastasis (LNneg) found in rectal cancer resection specimens varies and seems to be related to patient survival. Yet, the histopathological features influencing LNneg size in rectal cancer have not been studied in detail. Our pilot study focused on investigating the relationship between lymph node (LN) size and LNneg microarchitecture in rectal cancer (RC) resection specimens.

METHOD

In this retrospective cohort study, resection specimens from 146 RC patients, treated with either surgery alone (n = 29) or neoadjuvant therapy followed by resection (n = 117), were included in the study. Histology of LNnegs was reviewed to establish number of lymphoid follicles and presence of intranodal fat. Longest long axis and area of each LN were measured digitally.

RESULTS

1830 LNnegs were measured. The microarchitecture was analyzed in a subset of 680 LNnegs. 153 (22.5 %) LNnegs contained intranodal fat. After neoadjuvant treatment, presence of intranodal fat was related to smaller LNneg area (median (range) area of LNneg without intranodal fat: 4.51 mm² (0.15-46.89 mm²), with intranodal fat: 3.46 mm² (0.12-27.22 mm²), p = 0.048). A higher number of lymphoid follicles was related to a larger LNneg area in both patient groups (p < 0.001).

CONCLUSION

Our pilot data suggest that in rectal cancer the presence of large regional LNnegs may reflect increased immune activation due to tumor related antigens. Further studies are warranted to investigate whether histologically visible microarchitectural features of LNnegs such as lymphoid follicles translate to particular features in radiological images and hence could potentially help to identify LNneg with more certainty at the time of pre-treatment disease staging.

Mucin expression in gastric- and gastro-oesophageal signet-ring cell cancer: results from a comprehensive literature review and a large cohort study of Caucasian and Asian gastric cancer

BACKGROUND

The literature on the prognostic relevance of signet-ring cell (SRC) histology in gastric cancer (GC) is controversial which is most likely related to inconsistent SRC classification based on haematoxylin-eosin staining. We hypothesised that mucin stains can consistently identify SRC-GC and predict GC patient outcome.

METHODS

We performed a comprehensive literature review on mucin stains in SRC-GC and characterised the mucin expression in 851 Caucasian GC and 410 Asian GC using Alcian Blue (AB)-Periodic Acid-Schiff (PAS), MUC2 (intestinal-type mucin), and MUC5AC (gastric-type mucin). The relationship between mucin expression and histological phenotype [poorly cohesive (PC) including proportion of SRCs, non-poorly cohesive (non-PC), or mucinous (MC)], clinicopathological variables, and patient outcome was analysed.

RESULTS

Depending on mucin expression and cut-offs, the positivity rates of SRC-GC reported in the literature varied from 6 to 100%. Patients with MUC2 positive SRC-GC or SRC-GC with (gastro)intestinal phenotype had poorest outcome. In our cohort study, PC with ≥ 10% SRCs expressed more frequently MUC2, MUC5AC, and ABPAS (p < 0.001, p = 0.004 and p < 0.001, respectively). Caucasians with AB positive GC or combined ABPAS-MUC2 positive and MUC5AC negative had poorest outcome (all p = 0.002). This association was not seen in Asian patients.

CONCLUSIONS

This is the first study to suggest that mucin stains do not help to differentiate between SRC-GC and non-SRC-GC. However, mucin stains appear to be able to identify GC patients with different outcome. To our surprise, the relationship between outcome and mucin expression seems to differ between Caucasian and Asian GC patients which warrants further investigations.

Acetone clearance of mesocolic or mesorectal fat increases lymph node yield and may improve detection of high-risk Stage II colorectal cancer patients

AIM

Lymph node (LN) status is key to determining the need for adjuvant therapy in colorectal cancer (CRC) and for disease which has progressed to Stage II (T3-T4, N0, M0). A yield of fewer than 12 LNs is considered a risk factor similar to high-grade histology and vascular, lymphatic and perineural invasion. The aim of this retrospective study was to investigate the effect of acetone fat clearance of the mesocolon or mesorectum on LN yield and the identification of patients with high-risk Stage II CRC.

METHOD

After conventional LN retrieval, fatty tissue derived from the mesocolon or mesorectum of 80 CRC specimens was incubated in acetone for 24 h. A second dissection was then performed by a trained technician. The total number of LNs as well as tumour involvement (LNpositive and LNnegative) were assessed at each stage. In addition, LN morphology was assessed and clinicopathological data were extracted from existing pathology reports.

RESULTS

Eighty CRC specimens were available for study. 1548 (94%) LN were negative and 96 (6%) were positive. The median (range) LN yield per specimen was 12 (3-41) LN increasing to 18 (4-48) LN after fat clearance (P < 0.001). After fat clearance, 534 additional LNs were identified in 75 (94%) of the specimens, and all but 10 were negative. The pN stage did not change in six patients who were found to be LN positive after fat clearance. However, the number of high-risk Stage II CRC patients decreased from 11 to 7. Although important for these patients, this downstaging did not reach statistical significance (P = 0.125).

CONCLUSION

Acetone clearance of mesocolic or mesorectal fat increases median LN yield and may in a larger study decrease the number of patients classified as having high-risk Stage II CRC.

Epstein-Barr virus and mismatch repair deficiency status differ between oesophageal and gastric cancer: A large multi-centre study

BACKGROUND

Oesophageal (OeC) and gastric (GC) cancer patients are treated with similar multimodal therapy and have poor survival. There remains an urgent clinical need to identify biomarkers to individualise patient management and improve outcomes. Therapy with immune checkpoint inhibitors has shown promising results in other cancers. Proposed biomarkers to predict potential response to immune checkpoint inhibitors include DNA mismatch repair (MMR) and/or Epstein-Barr virus (EBV) status. The aim of this study was to establish and compare EBV status and MMR status in large multi-centre series of OeC and GC.

METHODS

EBV was assessed by EBV-encoded RNA (EBER) in situ hybridisation and MMR protein expression by immunohistochemistry (IHC) in 988 OeC and 1213 GC from multiple centres. In a subset of OeC, microsatellite instability (MSI) was tested in parallel with MMR IHC.

RESULTS

Frequency of MMR deficiency (MMRdef) and MSI was low in OeC (0.8% and 0.6%, respectively) compared with GC (10.3%). None of the OeCs were EBER positive in contrast to 4.8% EBER positive GC. EBV positive GC patients were younger (p = 0.01), more often male (p = 0.001) and had a better overall survival (p = 0.012). MMRdef GC patients were older (p = 0.001) and showed more often intestinal-type histology (p = 0.022).

CONCLUSIONS

This is the largest study to date indicating that EBV and MMRdef do not play a role in OeC carcinogenesis in contrast to GC. The potential clinical usefulness of determining MMRdef/EBV status to screen patients for eligibility for immune-targeting therapy differs between OeC and GC patients.

Pollination of Specklinia by nectar-feeding Drosophila: the first reported case of a deceptive syndrome employing aggregation pheromones in Orchidaceae

BACKGROUND AND AIMS

The first documented observation of pollination in Pleurothallidinae was that of Endrés, who noticed that the 'viscid sepals' of Specklinia endotrachys were visited by a 'small fly'. Chase would later identify the visiting flies as being members of the genus Drosophila. This study documents and describes how species of the S. endotrachys complex are pollinated by different Drosophila species.

METHODS

Specimens of Specklinia and Drosophila were collected in the field in Costa Rica and preserved in the JBL and L herbaria. Flies were photographed, filmed and observed for several days during a 2-year period and were identified by a combination of non-invasive DNA barcoding and anatomical surveys. Tissue samples of the sepals, petals and labellum of Specklinia species were observed and documented by SEM, LM and TEM. Electroantennogram experiments were carried out on Drosophila hydei using the known aggregation pheromones ethyl tiglate, methyl tiglate and isopropyl tiglate. Floral compounds were analysed by gas chromatography-mass spectometry using those same pheromones as standards.

KEY RESULTS

Flowers of S. endotrachys, S. pfavii, S. remotiflora and S. spectabilis are visited and pollinated by several different but closely related Drosophila species. The flies are arrested by aggregation pheromones, including ethyl tiglate, methyl tiglate and isopropyl tiglate, released by the flowers, and to which at least D. hydei is very sensitive. Visible nectar drops on the adaxial surface of sepals are secreted by nectar-secreting stomata, encouraging male and female Drosophila to linger on the flowers for several hours at a time. The flies frequently show courtship behaviour, occasionally copulating. Several different Drosophila species can be found on a single Specklinia species.

CONCLUSIONS

Species of the S. endotrachys group share a similar pollination syndrome. There seem to be no species-specific relationships between the orchids and the flies. It is not expected that Specklinia species will hybridize naturally as their populations do not overlap geographically. The combination of pheromone attraction and nectar feeding is likely to be a generalized pollination syndrome in Pleurothallidinae.

Irreversible renal damage after transient renin-angiotensin system stimulation: involvement of an AT1-receptor mediated immune response

Transient activation of the renin-angiotensin system (RAS) induces irreversible renal damage causing sustained elevation in blood pressure (BP) in Cyp1a1-Ren2 transgenic rats. In our current study we hypothesized that activation of the AT₁-receptor (AT₁R) leads to a T-cell response causing irreversible impairment of renal function and hypertension. Cyp1a1-Ren2 rats harbor a construct for activation of the RAS by indole-3-carbinol (I3C). Rats were fed a I3C diet between 4–8 weeks of age to induce hypertension. Next, I3C was withdrawn and rats were followed-up for another 12 weeks. Additional groups received losartan (20 mg/kg/day) or hydralazine (100 mg/kg/day) treatment between 4–8 weeks. Rats were placed for 24h in metabolic cages before determining BP at week 8, 12 and 20. At these ages, subsets of animals were sacrificed and the presence of kidney T-cell subpopulations was investigated by immunohistochemistry and molecular marker analysis. The development of sustained hypertension was completely prevented by losartan, whereas hydralazine only caused a partial decrease in BP. Markers of renal damage: KIM-1 and osteopontin were highly expressed in urine and kidney samples of I3C-treated rats, even until 20 weeks of age. Additionally, renal expression of regulatory-T cells (Tregs) was highly increased in I3C-treated rats, whereas the expression of T-helper 1 (Th1) cells demonstrated a strong decrease. Losartan prevented these effects completely, whereas hydralazine was unable to affect these changes. In young Cyp1a1-Ren2 rats AT₁R activation leads to induction of an immune response, causing a shift from Th1-cells to Tregs, contributing to the development of irreversible renal damage and hypertension.

Twenty-four-hour exposure to altered blood flow modifies endothelial Ca2+-activated K+ channels in rat mesenteric arteries

We tested the hypothesis that changes in arterial blood flow modify the function of endothelial Ca2+-activated K+ channels [calcium-activated K+ channel (K(Ca)), small-conductance calcium-activated K+ channel (SK3), and intermediate calcium-activated K+ channel (IK1)] before arterial structural remodeling. In rats, mesenteric arteries were exposed to increased [+90%, high flow (HF)] or reduced blood flow [-90%, low flow (LF)] and analyzed 24 h later. There were no detectable changes in arterial structure or in expression level of endothelial nitric-oxide synthase, SK3, or IK1. Arterial relaxing responses to acetylcholine and 3-oxime-6,7-dichlore-1H-indole-2,3-dione (NS309; activator of SK3 and IK1) were measured in the absence and presence of endothelium, NO, and prostanoid blockers, and 6,12,19,20,25,26-hexahydro-5,27:13,18:21,24-trietheno-11,7-metheno-7H-dibenzo [b,n] [1,5,12,16]tetraazacyclotricosine-5,13-diium dibromide (UCL 1684; inhibitor of SK3) or 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34; inhibitor of IK1). In LF arteries, endothelium-dependent relaxation was markedly reduced, due to a reduction in the endothelium-derived hyperpolarizing factor (EDHF) response. In HF arteries, the balance between the NO/prostanoid versus EDHF response was unaltered. However, the contribution of IK1 to the EDHF response was enhanced, as indicated by a larger effect of TRAM-34 and a larger residual NS309-induced relaxation in the presence of UCL 1684. Reduction of blood flow selectively blunts EDHF relaxation in resistance arteries through inhibition of the function of K(Ca) channels. An increase in blood flow leads to a more prominent role of IK1 channels in this relaxation.

Calcitonin gene-related peptide selectively relaxes contractile responses to endothelin-1 in rat mesenteric resistance arteries

We tested the hypothesis that endothelin-1 (ET-1) modulates sensory-motor nervous arterial relaxation by prejunctional and postjunctional mechanisms. Isolated rat mesenteric resistance arteries were investigated with immunohistochemistry, wire-myography, and pharmacological tools. ET(A)- and ET(B)-receptors could be visualized on the endothelium and smooth muscle and on periarterial fibers containing calcitonin gene-related peptide (CGRP). Arterial contractile responses to ET-1 (0.25-16 nM) were not modified by blockade of ET(B)-receptors, NO-synthase, and cyclooxygenase or desensitization of transient receptor potential cation channel, subfamily V, member 1 (TRPV1) with capsaicin. ET-1 reversed relaxing responses to CGRP in depolarized arteries. This effect was inhibited by ET(A)-antagonists. It was not selective because ET-1 also reversed relaxing responses to Na-nitroprusside (SNP) and because phenylephrine (PHE; 0.25-16 microM) similarly reversed relaxing responses to CGRP or SNP. Conversely, contractile responses to ET-1 were, compared with PHE, hypersensitive to the relaxing effects of the TRPV1-agonist capsaicin and to exogenous CGRP, but not to acetylcholine, forskolin, pinacidil, or SNP. In conclusion, ET-1 does not stimulate sensory-motor nervous arterial relaxation, but ET(A)-mediated arterial contractions are selectively sensitive to relaxation by the sensory neurotransmitter CGRP. This does not involve NO, cAMP, or ATP-sensitive K(+) channels.

High Sodium Intake Increases Blood Pressure and Alters Renal Function in Intrauterine Growth–Retarded Rats

A suboptimal fetal environment increases the risk to develop cardiovascular disease in the adult. We reported previously that intrauterine stress in response to reduced uteroplacental blood flow in the pregnant rat limits fetal growth and compromises renal development, leading to an altered renal function in the adult offspring. Here we tested the hypothesis that high dietary sodium intake in rats with impaired renal development attributable to intrauterine stress, results in increased blood pressure, altered renal function, and organ damage. In rats, intrauterine stress was induced by bilateral ligation of the uterine arteries at day 17 of pregnancy. At the age of 12 weeks, the offspring was given high-sodium drinking water (2% sodium chloride). At the age of 16 weeks, rats were instrumented for monitoring of blood pressure and renal function. After intrauterine stress, litter size and birth weight were reduced, whereas hematocrit at birth was increased. Renal blood flow, glomerular filtration rate, and the glomerular filtration fraction were increased significantly after intrauterine stress. High sodium intake did not change renal function and blood pressure in control animals. However, during high sodium intake in intrauterine stress offspring, renal blood flow, glomerular filtration rate, and the filtration fraction were decreased, and blood pressure was increased. In addition, these animals developed severe albuminuria, an important sign of renal dysfunction. Thus, a suboptimal fetal microenvironment, which impairs renal development, results in sodium-dependent hypertension and albuminuria.

Role of the Rhoa/Rho Kinase System in Flow-Related Remodeling of Rat Mesenteric Small Arteries in Vivo

In small arteries, a chronic blood flow reduction leads to inward hypotrophic remodeling, while a chronic blood flow elevation induces outward hypertrophic remodeling. The RhoA/Rho kinase system was shown to be modulated by shear stress, and to be involved in other kinds of vascular remodeling. The aim of this study was to investigate the role of RhoA/Rho kinase in flow-related small artery remodeling. Rat mesenteric small arteries were subjected to flow-modifying surgery. After 1, 2, 4, 16, and 32 days, the animals were sacrificed and small arteries were harvested. Messenger RNA was isolated and amplified. Using cDNA microarray analysis, the differential expression of >14,000 genes was analyzed, part of which was confirmed by RT-PCR. In vivo treatment with fasudil (3 mg/kg/day s.c.) was used to test the effect of Rho kinase inhibition. The main findings are that: (1) blood flow alteration modified the expression of approximately 5% of the genes by >2-fold, (2) flow reduction downregulated many RhoA-related cytoskeletal markers of smooth muscle cell phenotype, (3) many RhoA-related genes were rapidly (<1 day) regulated and (4) fasudil treatment potentiated the inward hypotrophic remodeling in response to chronically reduced flow. These results indicate the importance of the RhoA/Rho kinase system in flow-related small artery remodeling.

Reduced uteroplacental blood flow alters renal arterial reactivity and glomerular properties in the rat offspring

Fetal malnutrition and hypoxia may modify organ system maturation and result in cardiovascular diseases in the adult. We tested whether intrauterine stress (IUS) leads to persistent alterations of renal biology. In rats, intrauterine stress was induced by ligation of the uterine arteries at day 17 of pregnancy. Renal arteries of the 21-day-old male offspring were isolated to study pharmacological reactivity. Kidneys were dissected to analyze renal structure and beta-adrenoceptor expression. At 21 days of age, half of the animals underwent unilateral left nephrectomy. At the age of 12 weeks, rats were instrumented for blood pressure monitoring, blood sampling, and renal function measurements. After IUS, litter size and birth weight were reduced, whereas the hematocrit was increased. Renal arterial responses to beta-adrenergic stimulation and sensitivity to adenylyl cyclase activation were increased, along with the renal expression of beta2-adrenoceptors. At 21 days and at 6 months of age, the number and density of the glomeruli were reduced, whereas their size was increased. The filtration fraction and urinary albumin concentration were increased 12 weeks after intrauterine stress. In control rats, removal of the left kidney at 21 days of age did not affect kidney function and blood pressure. However, after IUS, the remaining right kidney failed to compensate for the loss of the left kidney, and blood pressure was increased. In conclusion, prenatal stress transiently modifies renal arterial reactivity and results in long-lasting adverse effects on renal structure and function and on renal compensatory mechanisms.

Tissue angiotensin-converting enzyme in imposed and physiological flow-related arterial remodeling in mice

OBJECTIVE

To test whether membrane-bound angiotensin I-converting enzyme (t-ACE) is involved in arterial remodeling, we applied unilateral carotid artery (CA) ligation and studied uterine arteries (UA) before, during, and after pregnancy in t-ACE-/- and t-ACE+/+ mice. RESULTS- In CA of t-ACE-/- mice, blood pressure, outer diameter (D), and medial cross-sectional area (mCSA) were reduced, whereas blood flow (BF) and the number of medial cells (mC) were not modified. In the ligated CA, mCSA and number of mC were increased while outer D and distensibility were reduced. These changes were significantly less pronounced in t-ACE-/- than t-ACE+/+ mice. In UA of t-ACE-/- mice, D was larger and mCSA was unaltered. At term pregnancy, D and mCSA of the UA were reversibly increased. Structural changes of UA during and after pregnancy were comparable in both strains.

CONCLUSIONS

t-ACE contributes to arterial structure and remodeling. It plays a major role in hyperplastic inward remodeling of the CA imposed by blood flow cessation, but it is not essential for outward hypertrophic and subsequent inward hypotrophic remodeling of the UA during and after pregnancy.

Chronic moderate hypoxia during in ovo development alters arterial reactivity in chickens

We previously observed arterial sympathetic hyperinnervation and endothelial dysfunction in the chicken embryo after exposure to chronic hypoxia. We now investigate whether changes in arterial properties could also be observed at 14-15 weeks of life. Eggs of White Leghorn chicken were incubated under normoxic or moderately hypoxic (15% O2 from days 6-19 of a 21-day incubation) conditions. Experiments were performed at 14-15 weeks of life under standard conditions (Hm: males exposed to hypoxia; Hf: females exposed to hypoxia; Nm: males exposed to normoxia; Nf: females exposed to normoxia). Body weight at hatching and at 14-15 weeks was not affected by in ovo exposure to hypoxia. Mean arterial pressure and heart rate were not significantly altered by chronic in ovo hypoxia. However, isolated femoral arteries were more sensitive to electrical stimulation (frequency in Hz of half-maximal contraction, Hm: 1.62+/-0.33, Hf: 1.92+/-0.88, Nm: 2.49+/-0.49, Nf: 2.83+/-0.31) and pharmacological stimulation of peri-arterial sympathetic nerves (contraction in N/m in response to tyramine: Hm: 5.27+/-0.85, Hf: 4.10+/-0.9, Nm: 2.26+/-0.67, Nf: 3.65+/-0.51, p=0.07) after in ovo hypoxia. In side branches of the femoral artery, the effect of NO synthase blockade with L-NAME on contraction (in N/m) in response to high K+ (Hm: 0.35+/-0.91, Hf: 1.29+/-0.36, Nm: 2.88+/-0.19, Nf: 2.79+/-0.58) and on the sensitivity to acetylcholine (DeltapD2, H: 0.32+/-0.11, N: 0.62+/-0.05) was reduced after in ovo hypoxia. The present study shows that exposure to chronic moderate hypoxia during development affects the contractile and relaxing arterial responses of 14- to 15-week-old chickens. Although hypoxia did not lead to changes in blood pressure at this age, the observed effects on arterial sympathetic and endothelial function may represent early signs of future cardiovascular abnormalities.

Vasodilator reactivity to calcitonin gene-related peptide is increased in mesenteric arteries of rats during early pregnancy

The objective of the present study was to determine the effect of early pregnancy on the sensitivity to, and endogenous production of calcitonin gene-related peptide (CGRP). Contractile responses of arteries of 10-day pregnant and nonpregnant rats were studied in myographs. During contractions induced by 40 mmol/l K(+), exogenous CGRP elicited an approximately 30% stronger relaxation in mesenteric arteries in pregnancy, an effect not seen in renal and uterine arteries. Capsaicin treatment during K(+)-induced contractions caused a persistent potentiation of the contractile response in mesenteric arteries, indicating that K(+) stimulates the endogenous release of CGRP. This potentiation was similar in the pregnant and nonpregnant state (+81 +/- 23% and +82 +/- 23%, respectively), suggesting no effect of pregnancy on the endogenous CGRP release. The latter was paralleled by comparable CGRP content in the arteries of both groups, indicating similar tissue CGRP availability. The results of this study support the concept that early pregnancy is associated with a rise in the vascular sensitivity to CGRP in selected areas of the vascular bed without concomitant increase in the vascular CGRP production and release.

Smooth muscle cell changes during flow-related remodeling of rat mesenteric resistance arteries

To obtain information on the molecular and cellular mechanisms of flow-induced arterial remodeling, we analyzed the morphology and smooth muscle cell (SMC) characteristics in rat mesenteric resistance arteries after interventions that decreased and increased flow. Juvenile male Wistar Kyoto rats were subjected to surgery that, compared with control arteries, provided arteries with chronic low flow and chronic high flow. Low flow resulted in a decreased passive lumen diameter, hypotrophy of the artery wall, and both loss and decreased size of SMCs. Time course studies, with intervention length ranging from 2 to 32 days of altered blood flow, showed that the narrowing of the lumen diameter in low-flow arteries appeared within 2 days and that an early dedifferentiation of SMC phenotype was indicated by markedly reduced levels of desmin mRNA. High flow resulted in an increased passive lumen diameter and in hypertrophy of the artery wall. The hypertrophy resulted from SMC proliferation because SMC number, measured by the 3D-dissector technique, was increased and immunohistochemical assessment of proliferating cell nuclear antigen also showed an increase. The widening of high-flow arteries required 16 days to become established, at which time desmin mRNA was reduced. This time was also required to establish changed wall mass in both low-flow and high-flow arteries. Apoptotic cells detected by TdT-mediated dUTP-biotin nick end labeling staining were mainly located in the medial layer, and evaluation of DNA fragmentation indicated that increased apoptosis occurred in both low flow and high flow. This study shows for the first time direct evidence that reduced and elevated blood flow in resistance arteries produce, respectively, decrease and increase in SMC number, with dedifferentiation of the SMCs in both cases.

Chronic hypoxia stimulates periarterial sympathetic nerve development in chicken embryo

BACKGROUND

Epidemiological findings suggest an association between low-for-age birth weight and the risk to develop coronary heart diseases in adulthood. During pregnancy, an imbalance between fetal demands and supply may result in permanent alterations of neuroendocrine development in the fetus. We evaluated whether chronic prenatal hypoxia increases arterial sympathetic innervation.

METHODS AND RESULTS

Chicken embryos were maintained from 0.3 to 0.9 of the 21-day incubation period under normoxic (21% O(2)) or hypoxic conditions (15% O(2)). At 0.9 incubation, the degree of sympathetic innervation of the embryonic femoral artery was determined by biochemical, histological, and functional (in vitro contractile reactivity) techniques. Chronic hypoxia increased embryonic mortality (32% versus 13%), reduced body weight (21.9+/-0.4 versus 25.4+/-0.6 g), increased femoral artery norepinephrine (NE) content (78.4+/-9.4 versus 57.5+/-5.0 pg/mm vessel length), and increased the density of periarterial sympathetic nerve fibers (14.4+/-0.7 versus 12.5+/-0.6 counts/10(4) microm(2)). Arteries from hypoxic embryos were less sensitive to NE (pD(2), 5.99+/-0.04 versus 6. 21+/-0.10). In the presence of cocaine, however, differences in sensitivity were no longer present. In the embryonic heart, NE content (156.9+/-11.0 versus 108.1+/-14.7 pg/mg wet wt) was also increased after chronic hypoxia.

CONCLUSIONS

In the chicken embryo, chronic moderate hypoxia leads to sympathetic hyperinnervation of the arterial system. In humans, an analogous mechanism may increase the risk for cardiovascular disease in adult life.

Altered flow-induced arterial remodeling in vimentin-deficient mice

The endothelial cytoskeleton plays a key role in arterial responses to acute changes in shear stress. We evaluated whether the intermediate filament protein vimentin is involved in the structural responses of arteries to chronic changes in blood flow (BF). In wild-type mice (V+/+) and in vimentin-deficient mice (V-/-), the left common carotid artery (LCA) was ligated near its bifurcation, and 4 weeks later, the structures of the occluded and of the contralateral arteries were evaluated and compared with the structures of arteries from sham-operated mice. Body weight and mean carotid artery BF did not differ between the strains, but LCA and right carotid artery (RCA) diameter (737+/-14 microm [LCA] and 723+/-14 microm [RCA] for V-/- versus 808+/-20 microm [LCA] and 796+/-20 microm [RCA] for V+/+) and medial cross-sectional area (CSAm) were significantly smaller in V-/- (21+/-1 and 22+/-2 x 10(3) microm(2) for LCA and RCA, respectively) than in V+/+ (28+/-2 and 28+/-3 x 10(3) microm(2) for LCA and RCA, respectively). In V+/+, LCA ligation eliminated BF in the occluded vessel (before ligation, 0. 35+/-0.02 mL/min) and increased BF from 0.34+/-0.02 to 0.68+/-0.04 mL/min in the RCA. In V-/-, the BF change in the occluded LCA was comparable (from 0.38+/-0.05 mL/min to zero-flow rates), but the BF increase in the RCA was less pronounced (from 0.33+/-0.02 to 0. 50+/-0.05 mL/min). In the occluded LCA of V+/+, arterial diameter was markedly reduced (-162 microm), and CSAm was significantly increased (5 x 10(3) microm(2)), whereas in the high-flow RCA of V+/+, carotid artery diameter and CSAm were not significantly modified. In the occluded LCA of V-/-, arterial diameter was reduced to a lesser extent (-77 microm) and CSAm was increased to a larger extent (10 x 10(3) microm(2)) than in V+/+. In contrast to V+/+, the high-flow RCA of V-/- displayed a significant increase in diameter (52 microm) and a significant increase in CSAm (5 x 10(3) microm(2)). These observations provide the first direct evidence for a role of the cytoskeleton in flow-induced arterial remodeling. Furthermore, they dissociate (1) between acute and chronic arterial responses to altered BF, (2) between alterations of lumen diameter and wall mass during arterial remodeling, and (3) between developmental and imposed flow-induced arterial remodeling.

Angiotensin II induces media hypertrophy and hyperreactivity in mesenteric but not epigastric small arteries of the rat

We examined effects of a 2-week infusion of angiotensin II (AII, 250 ng x kg[-1] x min[-1]) on properties of mesenteric resistance arteries (MrA) and superior epigastric arteries (SEA) of male Wistar rats. Histochemistry and pharmacological tools showed that MrA are densely innervated, whereas SEA are only sparsely innervated. AII infusion resulted in a significant elevation in mean arterial pressure and in plasma AII and noradrenaline levels. Organ chamber studies and morphometry were used to determine arterial contractile reactivity and structure. After AII infusion, in MrA (i) maximal contractile responses to 125 mM K+, noradrenaline, serotonin and adrenergic nerve stimulation were significantly increased, without modification of the sensitivity to these stimuli and (ii) a significant increase in media cross-sectional area and media thickness was observed without alterations in lumen diameter. The observed increase in vascular reactivity could fully be attributed to the observed increase in wall mass since no alterations in maximal active wall stress were noted. In SEA, no significant changes in responsiveness to vasoconstrictor stimuli or in wall structure were observed. These findings suggest that perivascular nerves are involved in the hypertrophy and subsequent hyperreactivity of small arteries in rats exposed for 2 weeks to a low dose of AII.

Coronary arterial hyperreactivity and mesenteric arterial hyporeactivity after myocardial infarction in the rat

After myocardial infarction, several neurohumoral systems become activated to maintain systemic perfusion pressure. We evaluated whether this leads to alterations of wall structure and contractile reactivity in the thoracic aorta, coronary septal artery, and mesenteric resistance arteries. In male Wistar rats, myocardial infarction (MI) was induced by permanent ligation of the left coronary artery. At 5 weeks after MI or sham operation, vessel segments were isolated, chemically sympathectomized, and mounted in a myograph for recording of isometric force development. Contractile reactivity to high potassium, norepinephrine, phenylephrine, serotonin, and Arg-vasopressin was determined. At the end of the experiments, vessels were fixed for morphometric analysis (cross-sectional area, media thickness, radius, and wall-to-lumen ratio). At 5 weeks after myocardial infarction, no alterations of contractile reactivity or wall structure were observed in the thoracic aorta of MI rats. In mesenteric resistance arteries, a nonselective reduction of maximal active wall tension and of active wall stress in response to vasoconstrictors was observed, whereas vessel wall structure and sensitivity to stimuli were not modified. On the other hand, coronary septal arteries displayed hyperreactivity to all strong contractile stimuli. These observations demonstrate a heterogeneity of arterial reactivity changes at 5 weeks after MI in the rat: (a) no alterations in thoracic aorta, (b) hyporeactivity of mesenteric resistance arteries despite maintenance of media mass, and (c) hyperreactivity of coronary vessels obtained from the hypertrophic remnant myocardium. This could result from the complex regional hemodynamic and neurohumoral changes associated with heart failure and may contribute to the further deterioration of cardiovascular function in this setting.

Reduced responsiveness of rat mesenteric resistance artery smooth muscle to phenylephrine and calcium following myocardial infarction

1. We evaluated responses of peripheral resistance arterial smooth muscle to alpha 1-adrenoceptor stimulation in a rat model of heart failure in relation to neurohumoral changes, wall structure, receptor density and cellular calcium handling. 2. Plasma samples and third order mesenteric artery side-branches were obtained from Wistar rats after induction of left ventricular infarction (M1) or sham surgery. Vessels were denuded of endothelium, sympathectomized, depleted of neuropeptides, and mounted in a myograph for recording of isometric force development in response to calcium, agonist and high potassium. Also, the morphology of these preparations was determined. Separate vessel segments were used in radioligand binding assays with [1H]-prazosin. 3. At 1 week after MI, circulating plasma levels of adrenaline, angiotensin II, atrial natriuretic factor (ANF) and vasopressin were significantly elevated. At 5 weeks only a significant elevation of ANF persisted. 4. At 5 weeks after MI, the structure of the vessels and responsiveness to high potassium or Bay K 8466 (10(6) mol l-1) were not modified. Yet, at this stage, sensitivity to phenylephrine was increased (pD2: 6.24 +/- 0.04 vs 5.98 +/- 0.04 for controls) while maximal contractile responses to phenylephrine in the presence of 2.5 mmol l-1 calcium (2.26 +/- 0.28 vs 3.53 +/- 0.34 N m-1) and the sensitivity to calcium in the presence of phenylephrine (pD2: 2.81 +/- 0.22 vs 3.74 +/- 0.16) were reduced. Responses to the agonist in calcium-free solution and the calcium sensitivity in the presence of 125 mmol l-1 potassium or of phorbol myristate acetate (PMA, 10(-6) mol l-1) were not altered. 5. At 5 weeks after MI, the density of prazosin binding sites was not reduced (4.04 +/- 1.40 vs 2.29 +/- 0.21 fmol microgram-1 DNA in controls). 6. In conclusion, myocardial infarction leads in the rat to a reduction of contractile responses of mesenteric resistance arterial smooth muscle to alpha 1-adrenoceptor stimulation. This seems to involve impaired agonist-stimulated calcium influx.

Effects of candidate autocrine and paracrine mediators on growth responses in isolated rat arteries

We evaluated the effects of mediators that can be produced by smooth muscle and endothelial cells on growth responses in isolated arteries. Segments of carotid and renal arteries, denuded of endothelium, were isolated from adult rats and studied during tissue culture in the presence of indomethacin. Three days of culture in the presence of serum stimulated DNA synthesis in the media. During long-term culture new layers of cells developed at the borders of the arterial segments. Medial DNA synthesis depended less on serum than extramedial cell proliferation. During moderate stimulation, basic fibroblast growth factor and endothelin-1 enhanced and interleukin-1 and transforming growth factor-beta reduced medial DNA synthesis, whereas insulin-like growth factor-1, platelet-derived growth factor AA, platelet-derived growth factor BB, and angiotensin II were without effect. Of these factors, only endothelin-1 stimulated extramedial cell proliferation. In addition, serum-stimulated but not basic fibroblast growth factor-stimulated medial DNA synthesis was less marked in arteries that had not been denuded of endothelium than in ee-endothelialized arteries. Differences between preparations with and without endothelium persisted in the absence of L-arginine and in the presence of an inhibitor of nitric oxide synthase. These observations confirmed that DNA synthesis in the arterial media and extramedial cell proliferation are influenced by different factors. They further indicated that endothelial modulation of medial DNA synthesis does not seem to involved endothelium-derived prostaglandins, nitric oxide, or interleukin-1 and that it can be blunted by basic fibroblast growth factor.

DNA synthesis in isolated arteries of normotensive and hypertensive rats: effects of the endothelium

OBJECTIVES

To compare DNA synthesis in isolated arteries of normotensive and hypertensive rats and to evaluate whether removal of the endothelium affects this process.

DESIGN

Carotid and renal artery segments were isolated from normotensive Wistar, Wistar-Kyoto (WKY) and Sprague-Dawley rats, and from spontaneously hypertensive rats (SHR), transgenic Sprague-Dawley rats harbouring the mouse Ren-2 gene and from WKY rats rendered hypertensive by aortic coarctation.

METHODS

Artery segments were exposed in vitro to serum with or without previous gentle removal of the endothelium. Nuclear incorporation of the thymidine analogue 5-bromo-2'-deoxyuridine was visualized by immunocytochemistry and the percentage of labelled medial nuclei was determined.

RESULTS

In both types of artery, obtained from 6-week-old WKY rats and from 6-week-old SHR, removal of endothelium increased the percentage of 5-bromo-2'-deoxyuridine-labelled medial nuclei (L%). Also, in the arteries of 20-week-old Wistar rats, WKY rats and WKY rats rendered hypertensive by aortic coarctation and in vessels of 11-week-old Sprague-Dawley rats and Sprague-Dawley rats harbouring the mouse Ren-2 gene, removal of endothelium increased L%. Conversely, in the arteries of 20-week-old SHR removal of the endothelium did not alter L%. Furthermore, maximally stimulated DNA synthesis was considerably smaller in de-endothelialized arteries of adult SHR than in denuded vessels from the other strains and models.

CONCLUSION

These findings confirm that the endothelium can reduce DNA synthesis in the intact rat arterial smooth muscle. This effect is not modified by hypertension, but is selectively reduced in the arteries of adult SHR.

Mesenteric small artery changes after vasoconstrictor infusion in young rats

We evaluated whether chronic alpha 1-adrenergic stimulation, angiotensin II (AII), or increased blood pressure (BP) alters resistance arterial structure and function. Structural parameters and wall tension were recorded in mesenteric small arteries (MrA) isolated from 6-week-old normotensive Wistar Kyoto rats that had been infused for 4 days with saline (WKY), 2 mg/kg/day phenylephrine (WKY + PHE), or 0.3 mg/kg/day AII (WKY + AII) and from saline-infused spontaneously hypertensive rats (SHR). During the experimental period, systolic BP (SBP) did not change in WKY but increased in WKY + PHE, WKY + AII, and SHR. Relative cardiac mass did not differ between SHR and WKY, but was increased in WKY + PHE and WKY + AII. Stiffness and optimal lumen diameter of MrA did not differ between WKY and SHR and were not altered in WKY + PHE or WKY + AII. Maximal contractile responses and sensitivities for vasconstrictors and calcium in vessels of WKY + AII and SHR did not differ from those in WKY. In vessels of WKY + PHE, maximal responses to vasoconstrictors and sensitivities for norepinephrine (NE) and PHE were reduced. Relaxing responses to isoproterenol (ISO) and Na-nitroprusside did not differ between SHR and WKY and were not altered in WKY + PHE and WKY + AII. Those to acetylcholine (ACh) were reduced in WKY + PHE. Media cross-sectional area and media thickness were significantly larger in WKY + AII and SHR as compared with WKY but were not altered in WKY + PHE. These data indicate that in young rats AII leads to small artery hypertrophy and that neither increased BP or increased vasconstriction appear to be involved therein. Chronic alpha 1-adrenergic stimulation, on the other hand, did not modify small artery structure but resulted in nonselective reduction of arterial smooth muscle contractile reactivity.

Tonic tone in arteries exposed continuously to angiotensin II in vitro

We evaluated long-term actions of angiotensin II (ATII) on arterial smooth muscle. In isolated sympathectomized renal artery segments that had been denuded of endothelium, isometric force was recorded during 3 days of incubation in nutrient medium with and without 1 microM ATII. The peptide induced, after an acute transient contraction and a latency of at least 12 hr, a slowly developing tonic increase in wall tension. This chronic effect was not influenced by indomethacin but could be reversed by sodium-nitroprusside. In vessels that had been chronically exposed to ATII, acute contractile responses to high potassium, serotonin and ATII were not altered. Also effects on agonist-induced tone of removal and readministration of extracellular potassium were not modified. Relaxing responses after exposure to NH4Cl were attenuated. During continuous exposure of isolated arteries to ATII, release of a stable contractile factor could not be detected, nuclear incorporation of the thymidine analog 5-bromo-2'-deoxyuridine was not stimulated, but the media cross-sectional area was significantly increased. These observations indicate that ATII induces in arterial smooth muscle, besides its well known acute contractile effect and its trophic action, a long-term tonic increase in tone. The mechanism largely remains to be established, but may involve altered cellular handling of hydrogen ions.

Endothelial modulation of DNA synthesis in isolated arteries of the rat

The endothelium can modulate the supply of growth factors to the underlying smooth muscle. In vitro experiments suggest that it may also influence the responsiveness of arterial smooth muscle to mitogens. In these experiments, we measured DNA synthesis in segments of carotid and renal arteries that were isolated from Wistar-Kyoto (WKY) rats and exposed to serum. Nuclear incorporation of the thymidine analogue, 5-bromo-2'-deoxyuridine (BrdUrd), was visualized by immunocytochemistry and the percentage of labeled nuclei (BrdUrd L%) was determined in the tunica media. In both types of artery isolated from 6- and 20-week-old WKY rats, mechanical removal of endothelium increased the BrdUrd L% in the tunica media. In carotid arteries of 20-week-old WKY rats, gentle denudation increased the incorporation of [3H]thymidine but not [14C]leucine. In denuded renal arteries of adult WKY rats, exogenous prostaglandin E2, iloprost, and transforming growth factor-beta (TGF-beta) reduced media labeling, which was not affected by Na nitroprusside. In renal arteries with endothelium, methylene blue and indomethacin did not affect medial DNA synthesis. These findings demonstrate that in arteries of young and adult rats, the endothelium reduces stimulated DNA synthesis. It is unlikely that basal production of nitric oxide or prostaglandins is involved herein. Endothelial inhibition of DNA synthesis but not protein synthesis in arteries indicates that the endothelium may influence the extent of arterial smooth muscle hypertrophy and hyperplasia.

In vivo DNA synthesis is not uniformly increased in arterial smooth muscle of young spontaneously hypertensive rats

We compared the distribution of DNA synthesis over the arterial tree of young normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) with marginally elevated blood pressure. Six-week-old male SHR and WKY rats were therefore infused with 5-bromo-2'-deoxyuridine (BrdUrd) for 2 days and the nuclear incorporation of the thymidine analogue in the media of various arteries was determined by immunohistochemistry. In WKY rats, 2.5% of the arterial smooth muscle nuclei in elastic, muscular and resistance arteries incorporated BrdUrd. In SHR, DNA synthesis was more marked in large arteries than in resistance arteries. It was in addition significantly larger in the aorta, superior mesenteric, renal and femoral arteries of the SHR than in those of the WKY rats. However, nuclear incorporation of BrdUrd in vivo did not differ between SHR and WKY rats in aortic endothelium, carotid arterial smooth muscle, nor in mesenteric or renal resistance arteries. Between 6 and 20 weeks of age, the number of nuclear profiles per media cross-section did not increase in large arteries of WKY rats and SHR. During this period of time, however, carotid artery and thoracic aorta weight and DNA content increased. SHR large arteries gained more DNA than those of WKY rats. These data indicate that DNA synthesis is uniformly distributed over the arterial system in young WKY rats and that DNA synthesis is elevated in the smooth muscle of large arteries of 6-week-old SHR but not in their resistance arteries.

Growth responses in isolated elastic, muscular and resistance-sized arterial segments of the rat

To evaluate whether intravascular phenomena contribute to local differences in growth responses of the arterial wall, we evaluated responses to organoid culture in a broad variety of arterial preparations. Arterial segments were isolated from adult, normotensive rats, sympathectomized, denuded from endothelium, and suspended in medium supplemented with serum. As judged from the nuclear incorporation of the thymidine analogue 5-bromo-2'-deoxyuridine (BrdUrd), this induced a transient stimulation of DNA synthesis in only a fraction of the arterial smooth muscle cells in all types of arteries. This intramedial DNA synthesis was more marked in renal arteries than in carotid arteries or aortae and was least pronounced in main pulmonary, femoral, and superior mesenteric artery and in mesenteric resistance-sized arteries. Organoid culture of isolated arteries did not increase the cross-sectional area of the media or the number of medial cells. It rather resulted in proliferation of smooth-muscle-like cells outside the media. In addition, smooth-muscle-like cells migrated out of the isolated arterial segments during culture. The rate of proliferation of these isolated cells did not differ between large arteries of different anatomical origin. However, isolated cells derived from mesenteric resistance arteries proliferated at a rate that was 4 times slower than that of large artery cells. The presence of endothelium significantly reduced medial DNA synthesis in carotid and renal artery segments, but not in mesenteric resistance-sized preparations. These data indicate that growth responses of the arterial wall differ quantitatively with the anatomical location and branching order of the vascular segment. In addition to the regional heterogeneity of endothelial effects on mitogenic responses of arterial smooth muscle, this seems to be due to regional differences in the susceptibility of arterial smooth muscle to exogenous growth factors. In this respect, we speculate that subsets of growth-resistant and growth-prone arterial smooth muscle cells could be heterogeneously distributed over the arterial tree.

DNA synthesis in isolated arteries. Kinetics and structural consequences

We evaluated changes in DNA synthesis, structure, and mechanical activity in isolated arteries during exposure to growth factors. Renal arteries were isolated from rats, sympathectomized, denuded of endothelium, and maintained in tissue culture. Up to 4 days of culture did not affect maximal contractile responses to depolarization. From the results of nuclear incorporation of the thymidine analogue 5-bromo-2-deoxyuridine (BrdUrd), culture stimulated DNA synthesis. In the media, incorporation of BrdUrd was maximal after 3 days but fell precipitously thereafter. Culture of arterial segments did not, however, increase the cross-sectional area of the media, the ploidy of the arterial nuclei, or the number of medial cells. In contrast, new layers of cells, part of which displayed smooth musclelike properties, developed at the border of the segments. The outermost edge of this newly formed layer continued to incorporate BrdUrd for at least 2 wk. These data demonstrate that stimulation of DNA synthesis by continuous exposure of the arterial wall to exogenous growth factors is 1) transient in the media; 2) does not, at least initially, compromise contractile reactivity; 3) does not alter gross medial structure; but 4) leads to proliferation of smooth musclelike cells outside the media. These findings suggest that the number of smooth muscle cells in the arterial media is maintained constant in the presence of even strong mitogenic stimuli.

Seroreactivity of patients with Crohn's disease with lymph nodes of primed nude mice is independent of the tissue used for priming

Athymic nude mice, injected with a cell-free filtrate of intestinal tissue from patients with Crohn's disease, have been shown to express antigens in their lymph nodes to which sera from patients with Crohn's disease contain antibodies. In the present study, immune reactivity was assessed with a histochemical indirect immunoperoxidase assay on paraplast-embedded tissue sections. The reactive lymph node cells were identified as sinus macrophages. We confirmed earlier findings of immunofluorescence studies that the reaction showed some antibody specificity, the proportion of patients with Crohn's disease who were positive (84%) being higher than of patients with ulcerative colitis (29%). However, reactivity of Crohn's disease sera was found to be antigen nonspecific, as it was equally observed with lymph nodes of mice primed with saline or with homogenates from patients with ulcerative colitis, diverticulitis, or volvulus. Hence, this nude mouse model does not seem appropriate to identify a transmissible etiology of Crohn's disease.