The Fas counterattack: Fas-mediated T cell killing by colon cancer cells expressing Fas ligand

Tumors escape immunological rejection by a diversity of mechanisms. In this report, we demonstrate that the colon cancer cell SW620 expresses functional Fas ligand (FasL), the triggering agent of Fas receptor (FasR)-mediated apoptosis within the immune system. FasL mRNA and cell surface FasL were detected in SW620 cells using reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemical staining, respectively. We show that SW620 kills Jurkat T cells in a Fas-mediated manner. FasR-specific antisense oligonucleotide treatment, which transiently inhibited FasR expression, completely protected Jurkat cells from killing by SW620. FasL-specific antisense oligonucleotide treatment of SW620 inhibited its Jurkat-killing activity. FasL has recently been established as a mediator of immune privilege in mouse retina and testis. Our finding that colon cancer cells express functional FasL suggests it may play an analogous role in bestowing immune privilege on human tumors. HT29 and SW620 colon cancer cells were found to express FasR mRNA and cell surface FasR using RT-PCR and immunofluorescence flow cytometry, respectively. However, neither of these cells underwent apoptosis after treatment by the anti-FasR agonistic monoclonal antibody CH11. Our results therefore suggest a Fas counterattack model for immune escape in colon cancer, whereby the cancer cells resist Fas-mediated T cell cytotoxicity but express functional FasL, an apoptotic death signal to which activated T cells are inherently sensitive.

Targeting HER2 aberrations as actionable drivers in lung cancers: phase II trial of the pan-HER tyrosine kinase inhibitor dacomitinib in patients with HER2-mutant or amplified tumors

BACKGROUND

HER2 mutations and amplifications have been identified as oncogenic drivers in lung cancers. Dacomitinib, an irreversible inhibitor of HER2, EGFR (HER1), and HER4 tyrosine kinases, has demonstrated activity in cell-line models with HER2 exon 20 insertions or amplifications. Here, we studied dacomitinib in patients with HER2-mutant or amplified lung cancers.

PATIENTS AND METHODS

As a prespecified cohort of a phase II study, we included patients with stage IIIB/IV lung cancers with HER2 mutations or amplification. We gave oral dacomitinib at 30-45 mg daily in 28-day cycles. End points included partial response rate, overall survival, and toxicity.

RESULTS

We enrolled 30 patients with HER2-mutant (n = 26, all in exon 20 including 25 insertions and 1 missense mutation) or HER2-amplified lung cancers (n = 4). Three of 26 patients with tumors harboring HER2 exon 20 mutations [12%; 95% confidence interval (CI) 2% to 30%] had partial responses lasting 3+, 11, and 14 months. No partial responses occurred in four patients with tumors with HER2 amplifications. The median overall survival was 9 months from the start of dacomitinib (95% CI 7-21 months) for patients with HER2 mutations and ranged from 5 to 22 months with amplifications. Treatment-related toxicities included diarrhea (90%; grade 3/4: 20%/3%), dermatitis (73%; grade 3/4: 3%/0%), and fatigue (57%; grade 3/4: 3%/0%). One patient died on study likely due to an interaction of dacomitinib with mirtazapine.

CONCLUSIONS

Dacomitinib produced objective responses in patients with lung cancers with specific HER2 exon 20 insertions. This observation validates HER2 exon 20 insertions as actionable targets and justifies further study of HER2-targeted agents in specific HER2-driven lung cancers.

CLINICALTRIALSGOV

NCT00818441.

The matrix metalloproteinases and their natural inhibitors: prospects for treating degenerative tissue diseases

Uncontrolled matrix metalloproteinase activity is thought to be a cause of the tissue damage observed in many disease processes. None of the drugs currently in use can prevent tissue destruction, and strategies for the development of synthetic inhibitors have been hampered by a poor understanding of the biochemistry of matrix metalloproteinases. Recent cDNA cloning efforts and characterization of recombinant human matrix metalloproteinases have permitted structure-function analysis of the enzymes and their inhibitors. Progress in this area should help indicate a route to rational strategies for designing lead therapeutic compounds.

Thrombosis in inflammatory bowel disease: clinical setting, procoagulant profile and factor V Leiden

Patients with inflammatory bowel disease have an increased frequency of thromboembolism, and microvascular thrombosis has been proposed as a contributory pathogenic factor. The mechanism of enhanced procoagulant activity is not understood. We examined the clinical setting of thromboembolic events in 52 patients with Crohn's disease or ulcerative colitis, and assessed the procoagulant laboratory profile, including Factor V Leiden, in a subset of 20 patients to identify procoagulant risk factors. Patients who developed thrombosis tended to be young; 60% of thrombotic events occurred in patients under 50 years. Multiple thromboembolic episodes occurred in 13% and unusual sites of thrombosis (e.g. intracardiac, cerebral, inominate veins) in 11%. No risk factor was identifiable in 52% of cases and two-thirds of thromboses occurred in an out-patient setting. The mortality rate was 8%. Evidence for inflammatory disease activity was found in only 45% of patients with ulcerative colitis at the time of the thromboembolic event, in contrast to 89% of those with Crohn's disease. Assays for specific coagulation defects were negative in all cases tested (protein S, C were normal in 17/17; anti-thrombin III, anti-phospholipid antibodies and activated protein C resistance were negative in 20/20, and only 1/20 patients was found to be heterozygous for Factor V leiden. Thrombosis in inflammatory bowel disease is important because it occurs in a young population, often in unusual sites, and has a high mortality. The development of thrombosis is related to active inflammatory disease in most patients with Crohn's disease but apparently not in those with ulcerative colitis. Since approximately half of the patients had no other identifiable risk factor, there remains a substantial group of patients with IBD who develop thrombosis for unknown reasons.

Immune privilege or inflammation? Insights into the Fas ligand enigma

Fas ligand (FasL) has become an enigmatic molecule: some evidence indicates that it contributes to immune privilege in tissues and tumors, whereas other data demonstrates that FasL can elicit inflammation. New findings may begin to reconcile the paradoxical effects of FasL.

Neurokinin-1 receptor expression in inflammatory bowel disease: molecular quantitation and localisation

BACKGROUND

Substantial evidence implicates the neuropeptide substance P (SP) in mucosal immunoinflammatory responses. Autoradiographic studies have suggested a disturbance in SP receptor expression in inflammatory bowel disease (IBD).

AIMS

Because of technical limitations such as poor cellular resolution with autoradiography, we used molecular methods to specifically localise the cellular expression of the neurokinin-1 receptor (NK-1R) in IBD colon, and to quantitate NK-1R mRNA expression levels therein.

METHODS

In situ hybridisation and immunohistochemistry were used to localise NK-1R mRNA and protein, respectively, in normal, ulcerative colitis (UC), and Crohn's disease (CD) colonic resections. NK-1R mRNA expression levels of normal, UC, and CD mucosal biopsies were quantitated by competitive reverse transcription-polymerase chain reaction.

RESULTS

NK-1R expression was localised to lamina propria mononuclear cells, epithelium, submucosal vasculature, smooth muscle, and myenteric plexus of normal and IBD colon. No ectopic NK-1R expression was observed in IBD. However, we found increased numbers of NK-1R expressing lymphoid cells in IBD tissue, aberrant negative epithelial expression of NK-1R in UC, and increased expression of NK-1R in CD myenteric plexus. Quantitation of NK-1R mRNA expression in IBD colonic mucosal biopsies revealed marked upregulation of NK-1R mRNA levels compared with non-inflamed mucosal expression levels (p<0.01).

CONCLUSIONS

This report demonstrates the strategic localisation and upregulation of NK-1R expression in IBD colon, and thereby suggests the involvement of substance P in the pathophysiological symptoms of IBD.

Fas ligand expression in primary colon adenocarcinomas: evidence that the Fas counterattack is a prevalent mechanism of immune evasion in human colon cancer

Fas ligand (FasL) kills sensitive Fas receptor (FasR)-bearing cells by inducing apoptosis. FasL expressed by non-lymphoid cells within the eye and the testis mediates immune privilege by inducing apoptosis of Fas-sensitive infiltrating pro-inflammatory immune effector cells. It has previously been demonstrated by the present authors that the colon cancer cell SW620 expresses FasL and can kill lymphoid cells by Fas-mediated apoptosis in vitro. This 'Fas counterattack' was subsequently confirmed by others as a potential mechanism of immune privilege in various malignancies. The aim of the present study was to ascertain the prevalence of FasL expression in human colon cancer and to confirm that neoplastic colonic epithelial cells express FasL in vivo. The study of FasL expression by colon cancer cell lines was extended: it was shown that seven of eight colon adenocarcinoma cell lines expressed FasL mRNA, using reverse transcription-polymerase chain reaction (RT-PCR). Prevalent expression of FasL was confirmed in vivo: all the resected colonic tumours examined (31/31) were found to express FasL. In the tumours, FasL were co-localized to neoplastic colonic epithelial cells, using immunohistochemistry and in situ hybridization, respectively. FasL expression was independent of Dukes' stage, suggesting that it may occur throughout colon cancer progression. These results suggest that FasL is a common mediation of immune privilege in colon cancer.

Evaluation of the pharmacological selectivity profile of alpha 1 adrenoceptor antagonists at prostatic alpha 1 adrenoceptors: binding, functional and in vivo studies

1. The profile of a range of alpha 1 adrenoceptor antagonists was determined in vitro against cloned human alpha 1A, alpha 1B and alpha 1D adrenoceptors and against noradrenaline-mediated contractions of rat aorta and human prostate. The in vivo profile of compounds was determined in an anaesthetized dog model which allowed the simultaneous assessment of antagonist potency against phenylephrine-mediated increases in blood pressure and prostatic pressure. 2. The quinazoline antagonists, prazosin, doxazosin and alfuzosin displayed high affinity but were non selective for the three cloned human alpha 1 adrenoceptors. Indoramin and SNAP 1069 showed selectivity for alpha 1A and alpha 1B adrenoceptors relative to the alpha 1D subtype. Rec 15/2739, WB 4101, SL 89,0591, (+)- and (-)- tamsulosin showed selectivity for alpha 1A and alpha 1D adrenoceptors relative to the alpha 1B subtype. RS 17053 showed high affinity and selectivity for alpha 1A adrenoceptors (pKi 8.6) relative to alpha 1B (pKi = 7.3) and alpha 1D (pKi = 7.1) subtypes. 3. (+)-Tamsulosin, (-)-tamsulosin, SL 89,0591, Rec 15/2739, SNAP 1069 and RS 17053 appeared to act as competitive antagonists of noradrenaline-mediated contractions of rat aorta yielding pA2 affinity estimates which were similar to binding affinities at cloned human alpha 1D adrenoceptors. The following rank order was obtained: prazosin = (-)-tamsulosin > doxazosin > SL 89,0591 = (+)-tamsulosin > Rec 15/2739 > RS 17053 = SNAP 1069. 4. (-)-Tamsulosin was a very potent, insurmountable antagonist of noradrenaline-mediated contractions of human prostate, yielding an approximate pA2 estimate of 9.8 at 1 nM. The corresponding (+)-enantiomer was 30 fold weaker. SL 89,0591, SNAP 1069 and Rec 15/2739 yielded pA2 estimates which compared well with their alpha 1A binding affinities. The affinity estimate for prazosin on human prostate was lower than the corresponding binding affinity determined at alpha 1A adrenoceptors and RS 17053 was a very weak antagonist on human prostate (pA2 = 6.0) relative to the high affinity (pKi = 8.6) determined at cloned human alpha 1A adrenoceptors. 5. In the anaesthetized dog, in vivo pseudo "pA2' values showed that doxazosin, (+)- and (-)-tamsulosin inhibited phenylephrine-induced increases in prostatic and blood pressure with similar affinity, implying that these agents show little or no selectivity for prostatic responses in this model. SL 89,0591 and SNAP 1069 were moderately selective (3 and 6 fold respectively) for prostatic pressure relative to blood pressure. Rec 15/2739 was a more potent antagonist of phenylephrine-mediated increases in prostatic pressure ("pA2' = 8.74) compared to blood pressure ("pA2' = 7.51). 6. Data in this study suggest that the alpha 1 adrenoceptor mediating noradrenaline-induced contractions of human prostate, whilst having some of the characteristics of an alpha 1A adrenoceptor, cannot be satisfactorily aligned with cloned alpha 1A, alpha 1B or alpha 1D adrenoceptors. In addition, studies in the anaesthetized dog have shown that agents having high affinity and selectivity for prostatic alpha 1 adrenoceptors, particularly over the alpha 1D subtype, appear to inhibit phenylephrine-induced increases in prostatic pressure selectively compared to blood pressure.

PCR detection of Mycobacterium paratuberculosis in Crohn's disease granulomas isolated by laser capture microdissection

BACKGROUND AND AIMS

The uncertainty surrounding the role of Mycobacterium avium subsp paratuberculosis (Map) in Crohn's disease has been compounded by possible contamination from Map present in the lumen microflora. This study used laser capture microdissection (LCM) and polymerase chain reaction (PCR) to detect Map DNA in subepithelial granulomas, isolated from 15 surgically resected, formalin fixed specimens of granulomatous Crohn's disease and from 12 granulomatous disease controls (10 bowel, 2 non-bowel).

METHODS

The effect of amplicon size on reliability of PCR from formalin fixed samples was examined by amplifying 435 bp and 133 bp sequences of the human APC gene. After this, nested primers were designed to detect a small fragment (155 bp) of the Map specific IS900 gene in Crohn's granulomas. LCM isolated granulomas from Map culture positive bovine intestine was used as positive control. PCR product specificity was confirmed by direct DNA sequencing.

RESULTS

The smaller, but not the larger, fragment of the APC gene amplified reliably in all samples. Amplification of the 155 bp fragment of the IS900 gene detected Map DNA in microdissected Crohn's granulomas in 6 of 15 cases, and in 0 of 12 disease control granulomas.

CONCLUSIONS

LCM can be used to detect Map DNA in granulomas in a proportion of patients with Crohn's disease. However, formalin fixation requires that comparatively short DNA fragments of the Map specific IS900 gene be targeted, to permit consistent detection. Detection of Map DNA within granulomas might suggest an infectious aetiology in a subset of patients; alternatively, a transmissible agent may not be involved but mycobacterial DNA may influence pathogenesis by modifying the local cytokine responses.

Structure of poliovirus type 2 Lansing complexed with antiviral agent SCH48973: comparison of the structural and biological properties of three poliovirus serotypes

BACKGROUND

Polioviruses are human pathogens and the causative agents of poliomyelitis. Polioviruses are icosahedral single-stranded RNA viruses, which belong to the picornavirus family, and occur as three distinct serotypes. All three serotypes of poliovirus can infect primates, but only type 2 can infect mice. The crystal structures of a type 1 and a type 3 poliovirus are already known. Structural studies of poliovirus type 2 Lansing (PV2L) were initiated to try to enhance our understanding of the differences in host range specificity, antigenicity and receptor binding among the three serotypes of poliovirus.

RESULTS

The crystal structure of the mouse neurovirulent PV2L complexed with a potent antiviral agent, SCH48973, was determined at 2.9 A resolution. Structural differences among the three poliovirus serotypes occur primarily in the loop regions of the viral coat proteins (VPs), most notably in the loops of VP1 that cluster near the fivefold axes of the capsid, where the BC loop of PV2L is disordered. Unlike other known structures of enteroviruses, the entire polypeptide chain of PV2L VP4 is visible in the electron density and RNA bases are observed stacking with conserved aromatic residues (Tyr4020 and Phe4046) of VP4. The broad-spectrum antiviral agent SCH48973 is observed binding in a pocket within the beta-barrel of VP1, in approximately the same location that natural 'pocket factors' bind to polioviruses. SCH48973 forms predominantly hydrophobic interactions with the pocket residues.

CONCLUSIONS

Some of the conformational changes required for infectivity and involved in the control of capsid stability and neurovirulence in mice may occur in the vicinity of the fivefold axis of the poliovirus, where there are significant structural differences among the three poliovirus serotypes in the surface exposed loops of VP1 (BC, DE, and HI). A surface depression is located at the fivefold axis of PV2L that is not present in the other two poliovirus serotypes. The observed interaction of RNA with VP4 supports the observation that loss of VP4 ultimately leads to the loss of viral RNA. A model is proposed that suggests dual involvement of the virion fivefold and pseudo-threefold axes in receptor-mediated initiation of infection by picornaviruses.

Human progelatinase A can be activated by matrilysin

The activation of human progelatinase A by other matrix metalloproteinases was studied by following both the loss of its N-terminal propeptide and the accompanying increase in the rate of hydrolysis of a synthetic substrate. Activated stromelysin 1 was unable to cause any activation of progelatinase A beyond that slowly occurring by autolysis, but an 8 h incubation with activated matrilysin was able to produce 64% of the activity generated by incubation with (4-aminophenylmercuric)acetate (APMA). Wild-type progelatinase A and a mutant proenzyme that cannot become active were both cleaved by matrilysin to a lower molecular weight species that had lost the propeptide. This shows that matrilysin activates progelatinase A by removing the propeptide in a process that does not require any autolytic cleavages.

Altered mechanisms of apoptosis in colon cancer: Fas resistance and counterattack in the tumor-immune conflict

Fas (CD95/APO-1) is a cell surface "death receptor" that mediates apoptosis upon engagement by its ligand, FasL. Fas-mediated apoptosis of lymphocytes normally serves immunoregulatory roles, including tolerance acquisition, immune response termination, and maintenance of immune privilege in certain organs. Colon tumors can exploit this lymphocyte death program by expressing FasL. This may enable colon tumors to mount a "Fas counterattack" against antitumor lymphocytes, impairing antitumor immune responses. FasL-expressing colon tumor-derived cell lines can trigger Fas-mediated apoptosis of cocultured T cells in vitro. FasL expressed in esophageal cancer has been significantly associated with apoptosis and depletion of tumor-infiltrating lymphocytes (TIL) in vivo. FasL may also facilitate metastatic colonization of Fas-sensitive organs such as the liver, by inducing apoptosis of target organ cells. Normal colonic epithelial cells express Fas and are relatively sensitive to Fas-mediated apoptosis. By contrast, colon tumor-derived cell lines are usually resistant to induction of Fas-mediated apoptosis, and colon cancer cells frequently coexpress Fas and FasL. The mechanisms allowing resistance to Fas-mediated apoptosis are complex, and defects have been identified at several levels of Fas signal transduction. The "Bcl-2 rheostat" may be pitched against apoptosis in colon cancer, inasmuch as overexpression of Bcl-2, downregulation of Bak, and mutation of Bax are common defects in colon tumors. Caspase-1 is also downregulated in colon cancer. The high frequency of p53 mutations in late-stage cancers may also inhibit Fas signaling. Fundamental defects in apoptosis signaling may contribute to both immuno- and chemoresistance in colon cancer and allow expression of FasL to counterattack antitumor lymphocytes.

Comparison of cryopreserved amniotic membrane and umbilical cord tissue with dehydrated amniotic membrane/chorion tissue

OBJECTIVE

To evaluate how the different processing methods cryopreservation and dehydration affect the structural integrity and biological composition of key signalling molecules within amniotic membrane and umbilical cord tissues.

METHOD

We directly compared cryopreserved amniotic membrane (AM) and umbilical cord (UC) tissues with dehydrated amniotic membrane/chorion (dHACM) tissue using biochemical and functional assays including histological and histochemical staining, BCA, agarose gel electrophoresis, western blot, ELISA, and proliferation and cell death assays.

RESULTS

Cryopreservation retains the native architecture of the AM/UC extracellular matrix and maintains the quantity and activity of key biological signals present in fresh AM/UC, including high molecular weight hyaluronic acid, heavy chain-HA complex, and pentraxin 3. In contrast, dehydrated tissues were structurally compromised and almost completely lacked these crucial components.

CONCLUSION

The results presented here indicate that cryopreservation better preserves the structural and biological signaling molecules of foetal tissues.

Aneuploidy, an early event in mouse skin tumor development

It has been suggested that chromosomal alterations can play a role in mouse skin carcinogenesis. These changes have been proposed as a possible mechanism of action of tumor promoters and they have also been related to the conversion of benign papillomas to carcinomas. However, direct evidence showing the chromosomal constitution of these tumors has not been previously described. Here we show the presence of aneuploid cells in very early papillomas and the eventual displacement of the diploid stem line by aneuploid clones at later stages. Squamous cell carcinomas (SCC) induced by the same protocol were highly aneuploid. These results suggest that genomic imbalance produced by aneuploidy may be related to the malignant conversion of the benign papillomas.

Racial disparities in health status: a comparison of the morbidity among American Indian and U.S. adults with diabetes

OBJECTIVE

American Indians and Alaska Natives are 2.3 times more likely to have diabetes than are individuals in the U.S. general population. The objective of this study was to compare morbidity among American Indian and U.S. adults with diabetes.

RESEARCH DESIGN AND METHODS

We extracted demographic and health service utilization data for an adult American Indian population aged 18-64 years (n = 30,121) served by the Phoenix Service Unit from the Indian Health Service clinical reporting system. Similar data for a U.S. population (n = 1,500,002) with commercial health insurance, matched by age and sex to the American Indian population, were drawn from the MartketScan Research Database. We used Diagnostic Cost Groups to identify medical conditions for which each individual was treated and to assign a risk score to quantify his or her morbidity burden. We compared the prevalence of comorbidities and morbidity burden of American Indian and U.S. adults with diabetes.

RESULTS

American Indians with diabetes had significantly higher rates of hypertension, cerebrovascular disease, renal failure, lower-extremity amputations, and liver disease than commercially insured U.S. adults with diabetes (P < 0.05). The American Indian prevalence rates were 61.2, 6.9, 3.9, 1.8, and 7.1%, respectively. The morbidity burden among the American Indian with diabetes exceeded that of the insured U.S. adults with diabetes by 50%.

CONCLUSIONS

The morbidity burden associated with diabetes among American Indians seen at the Phoenix Service Unit far exceeded that of commercially insured U.S. adults. These findings point to the urgency of enhancing diabetes prevention and treatment services for American Indians/Alaska Natives to reduce diabetes-related disparities.

Viral load and clinicopathological features of chronic hepatitis C (1b) in a homogeneous patient population

Monitoring the progression of hepatitis C virus (HCV) includes clinical, biochemical, and histological parameters. Quantitation of viral load by reverse-transcription polymerase chain reaction (RT-PCR) may offer a more reliable marker of disease status. Conflicting reports on viral titers may reflect heterogeneity of patient population, mode of infection, and viral type/subtype. The aim of this study was to correlate quantitative serum viral load with alanine transaminase (ALT) and histological status in a homogenous population. The study population consisted of 77 Rhesus-negative women with chronic hepatitis C type 1b. Homogenous features of this study population included: same defined source of infection (contaminated anti-D immunoglobulin); same duration of disease (17 years at the time of study); same viral type/subtype; same ethnic origin; all healthy child-bearing females at the time of infection; and an absence of competing risk factors for infectious and other liver diseases. None of the patients had received antiviral treatment at the time of study. Liver biopsy was performed on all patients. All biopsies were scored by a single histopathologist who was blinded to the clinical and viral status of each patient. A weak, but statistically significant, correlation (rs =.26; P <.05) between serum viral load and the degree of inflammation (mean value: 3.87 +/- 2.17 [SD]) was found. There was no significant correlation between serum viral load and the degree of fibrosis (mean value: 0.84 +/- 0.8 [SD]; P =.06). There was no significant correlation between serum viral load and ALT, although there was a correlation between ALT and the degree of inflammation (rs =.241; P =.035).

Effect of different housing conditions on behaviour and foot lesions in Friesian heifers

Spring-calving Friesian heifers were randomly allocated either to Dutch Comfort cubicles (2130 x 1160 mm) bedded with rubber mats or to modified Newton Rigg cubicles (2060 x 1090 mm) without bedding. Their behavioural activities, including lying down and standing, were monitored every 30 minutes for two days and two nights each week from November to March, and all four feet of each animal were examined at housing, at calving and monthly thereafter. During January, February and March the 22 heifers in the Dutch Comfort cubicles lay down significantly longer and spent significantly less time standing half-in the cubicles than the 21 heifers in the Newton Rigg cubicles (P < 0.01). Claw health deteriorated in all the animals after housing, but less in the heifers in the Dutch Comfort cubicles, at both one and two months after calving (P < 0.05). There were moderate correlations between the lying behaviour and the total foot lesions and the lesions in the sole ulcer area of the heifers in the Dutch Comfort cubicles but none for the heifers in the Newton Rigg cubicles, possibly because lameness is a multifactorial condition and other factors may have masked the effect of lying down on foot lesions in this group. The better conditions provided by the Dutch Comfort cubicles were associated with better claw health and this effect was partially mediated through the increased time spent lying down by the heifers in these cubicles.

Changes in human dendritic cell number and function in severe obesity may contribute to increased susceptibility to viral infection

Dendritic cells (DCs) are key immune sentinels linking the innate and adaptive immune systems. DCs recognise danger signals and initiate T-cell tolerance, memory and polarisation. They are critical cells in responding to a viral illness. Obese individuals have been shown to have an impaired response to vaccinations against virally mediated conditions and to have an increased susceptibility to multi-organ failure in response to viral illness. We investigated if DCs are altered in an obese cohort (mean body mass index 51.7±7.3 kg m(-2)), ultimately resulting in differential T-cell responses. Circulating DCs were found to be significantly decreased in the obese compared with the lean cohort (0.82% vs 2.53%). Following Toll-like receptor stimulation, compared with lean controls, DCs generated from the obese cohort upregulated significantly less CD83 (40% vs 17% mean fluorescence intensity), a molecule implicated in the elicitation of T-cell responses, particularly viral responses. Obese DCs produced twofold more of the immunosuppressive cytokine interleukin (IL)-10 than lean controls, and in turn stimulated fourfold more IL-4-production from allogenic naive T cells. We conclude that obesity negatively impacts the ability of DCs to mature and elicit appropriate T-cell responses to a general stimulus. This may contribute to the increased susceptibility to viral infection observed in severe obesity.

Prescription drug spending: the impact of age and chronic disease status

OBJECTIVES

The purpose of this study was to examine how pharmaceutical expenditures vary by age and the presence of chronic health problems.

METHODS

Data from the 1987 National Medical Expenditure Survey were used to obtain nationally representative estimates of outpatient prescription drug expenditures for the noninstitutionalized population and the fraction of total health expenditures used to purchase medications for age-chronic disease population subgroups.

RESULTS

Although the elderly make up 12% of the population, they account for 34% of total pharmaceutical expenditures. Pharmaceutical expenditures are 9% of total expenditures for children, 13% for nonelderly adults, and 23% for the elderly. Among nonelderly adults, approximately one third have at least one chronic condition and account for over two thirds of drug expenditures. Among the elderly, 36% have three or more chronic conditions and account for 57% of drug expenditures for this group; 41% of total drug expenditures are for cardiovascular or renal drugs.

CONCLUSIONS

Significant pharmaceutical spending is for treatment of chronic conditions, which subjects insurance coverage to adverse selection and could affect the design of prescription drug benefit packages. Current enrollees in Medicare risk management plans who have drug benefits may face significantly higher out-of-pocket expenses for pharmaceuticals if capitation rates are cut as a means of controlling Medicare program expenditures.

Acromegaly and colorectal cancer: a comprehensive review of epidemiology, biological mechanisms, and clinical implications

Acromegaly is an endocrine disorder characterised by sustained hypersecretion of growth hormone (GH) with concomitant elevation of insulin-like growth factor (IGF)-I, and is associated with malignancy and premature mortality from cardiovascular and respiratory diseases. In particular, there may be an increased risk of colorectal neoplasia, but the exact extent of this is contentious. Colonoscopy-based studies of adenoma prevalence rates in acromegalic patients are misleading, but population-based studies on colorectal cancer risk are more consistent - a meta-analysis estimated a pooled risk ratio of 2.04 (95 % CI: 1.32, 3.14). Possible mechanisms underlying this increased risk include direct actions as a consequence of elevated levels of circulating GH and IGF-I and/or other perturbations within the IGF system. Other possible mechanisms include altered bile acid secretion, altered cellular immunity, hyperinsulinaemia, shared genetic susceptibility and increased bowel length. However, most explanations only offer indirect evidence, and the expectation of acromegaly as a natural model of colorectal carcinogenesis has not materialised. From a clinical perspective, it seems reasonable to consider a once-only colonoscopic screening at approximately age 55 years, but potential risks and benefits should be balanced.