The effects of CCR5 inhibition on regulatory T-cell recruitment to colorectal cancer.

BACKGROUND: Regulatory T cells (Treg) are enriched in human colorectal cancer (CRC) where they suppress anti-tumour immunity. The chemokine receptor CCR5 has been implicated in the recruitment of Treg from blood into CRC and tumour growth is delayed in CCR5-/- mice, associated with reduced tumour Treg infiltration. METHODS: Tissue and blood samples were obtained from patients undergoing resection of CRC. Tumour-infiltrating lymphocytes were phenotyped for chemokine receptors using flow cytometry. The presence of tissue chemokines was assessed. Standard chemotaxis and suppression assays were performed and the effects of CCR5 blockade were tested in murine tumour models. RESULTS: Functional CCR5 was highly expressed by human CRC infiltrating Treg and CCR5(high) Treg were more suppressive than their CCR5(low) Treg counterparts. Human CRC-Treg were more proliferative and activated than other T cells suggesting that local proliferation could provide an alternative explanation for the observed tumour Treg enrichment. Pharmacological inhibition of CCR5 failed to reduce tumour Treg infiltration in murine tumour models although it did result in delayed tumour growth. CONCLUSIONS: CCR5 inhibition does not mediate anti-tumour effects as a consequence of inhibiting Treg recruitment. Other mechanisms must be found to explain this effect. This has important implications for anti-CCR5 therapy in CRC.

Evaluation of serum lysyl oxidase as a blood test for colorectal cancer.

AIMS: Lysyl oxidase (LOX) expression is elevated in colorectal cancer (CRC) tissue and associated with disease progression. A blood test may form a more acceptable diagnostic test for CRC although LOX has not previously been measured in the serum. We therefore sought to determine the clinical usefulness of a serum LOX test for CRC in a symptomatic population. METHODS: Adult patients referred to a hospital colorectal clinic with bowel symptoms completed a questionnaire and provided a blood sample for serum LOX measurement. Associations between presenting symptoms, serum LOX concentrations and outcomes of investigations were tested by univariate and multivariate analyses to determine if serum LOX was clinically useful in the prediction of CRC. LOX expression in CRC and adjacent colon biopsies was evaluated by ELISA and immunohistochemistry. RESULTS: Thirty-one cases of colorectal cancer and 16 high-risk polyps were identified from a total of 962 participants. There was no association between serum LOX concentration and the presence of CRC, high-risk polyps or cancers at any site. LOX expression was significantly increased in CRC tissue compared to adjacent colon. CONCLUSION: Despite overexpression of LOX in CRC tissue, elevated serum levels could not be demonstrated. Serum LOX measurement is therefore not a clinically useful test for CRC.

Genetic testing and early diagnosis and intervention: boon or burden?

The possibility of early diagnosis and intervention is radically changed by the advent of genetic testing. The recent report of the Nuffield Council on Bioethics is timely and helpful. I have suggested, that not only the severity of the disability indicated by genetic information, and the accuracy of the data, ought to govern the approach to the implementation of screening for genetic disorders. In addition, assessment of the value of the information to those involved should be considered. The efficacy of the available therapeutic measures, combined with the prognostic data are important indices of the value of the information. These measures fall into three categories and thus indicate that three different courses of intervention may be appropriate. Three approaches to diagnosis and intervention are then outlined, drawing on the experience of various clinical initiatives.

Effects of clonidine on vascular responses in kidney and hindlimbs of cats.

1. Cardiovascular reflexes to intravenous adrenaline and histamine and to carotid occlusion were studied in the renal vasculature, and direct effects of noradrenaline and clinidoine were compared in renal and hindlimb vascular beds in anaesthetized cats. 2. Unlike its reported effects on cardiovascular reflexes in the hindlimbs, clonidine depressed all three reflexes in the kidneys. 3. Noradrenaline caused vasoconstriction when given directly into both renal and hindlimb circulartions, but clonidine produced vasoconstriction only in the hindlimb vascular bed. 4. These results suggest that alpha-adrenoceptors in the reanl vasculature may be different from those in the hindlimbs, and that the cardiovascular reflexes in these two areas are under different control.