GB virus C coinfection and vertical transmission in HIV-infected mothers before the introduction of antiretroviral prophylaxis

OBJECTIVES

To investigate the prevalence of GB virus C (GBV-C) viraemia and GBV-C antibodies in a cohort of HIV-infected mothers and their infants between 1987 and 1994.

METHODS

GBV-C viraemia and antibodies were determined by polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) in 52 HIV-infected mothers and their 53 infants, who were born before antiretroviral prophylaxis for reduction of HIV transmission was introduced at the end of 1994. Ten of these children acquired HIV.

RESULTS

Mothers of three children had GBV-C viraemia and mothers of another 14 children carried antibodies against GBV-C. No mother had GBV-C antibodies and GBV-C viraemia simultaneously. GBV-C viraemia was detected in only one infant. This child was delivered by the vaginal route to a mother with GBV-C viraemia, and was not HIV-infected. No vertical transmission of GBV-C occurred from mothers with GBV-C antibodies. However, four of 10 children who were infected with HIV had a mother with past or ongoing GBV-C infection.

CONCLUSION

Our findings suggest that the risk of vertical transmission of GBV-C is not elevated in HIV-infected mothers. Furthermore, although the number of HIV-1-infected children was low, we saw no evidence that the presence of ongoing or past GBV-C infection influenced the probability of vertical HIV transmission.

Multiple effects of alpha1-antitrypsin on breast carcinoma MDA-MB 468 cell growth and invasiveness

The degradation of extracellular matrix during cancer invasion results from the action of several protease and protease inhibitor systems. Alpha(1)-Antitrypsin (AAT) is a serine proteinase inhibitor produced by various tumour cells, and its plasma concentration rises during inflammation, infection and malignant diseases. AAT is found in a native, inhibitory active form, but also in other, non-inhibitory forms including cleaved and/or degraded. To test a hypothesis that AAT dependent on its molecular form may have multiple effects on tumour cell behaviour, breast cancer cells, MDA-MB 468, were cultured alone or stimulated with a native AAT or its C-terminal fragment (C-36) at a concentration of 5 micromol/l for 2, 24 and 48 hours. Native AAT added to the cells for 2 hours enhanced transforming growth factor beta 1 (TGFbeta1) levels by 50%, but inhibited cell proliferation (by 61%), reduced interleukin 6 (IL-6) levels (by 87%) and activity (by about 66%), compared with non-stimulated cells. Native AAT showed similar, but less pronounced, effects when added to the cells for 24 and 48 hours. Under the same experimental conditions the cells exposed to the C-36 peptide significantly increased in proliferation, invasiveness and showed higher IL-6 levels. In addition, cells treated with the C-36 for 48 hours increased in NFkappaB (nuclear factor kappa B) activity. These results indicate that AAT, dependent on its molecular form, can both suppress and induce breast tumour cell biological activity in vitro.

CD4 T cell activation by myelin oligodendrocyte glycoprotein is suppressed by adult but not cord blood CD25+ T cells

Regulatory T cells expressing CD25 have been shown to protect rodents from organ-specific autoimmune diseases. Similar CD25+ cells with a memory phenotype exerting suppressive function after polyclonal or allogeneic stimulation are also present in adult human blood. We demonstrate that adult human CD25+ cells regulate the response to myelin oligodendrocyte glycoprotein (MOG), as depletion of CD25(+) cells increases responses of PBMC and the addition of purified CD25+ cells suppresses MOG-specific proliferation and IFN-gamma production of CD4(+)CD25(-) T cells. In contrast, cord blood CD25+ cells do not inhibit responses to self antigens, and only a small subpopulation of cord CD25+ cells expresses the typical phenotype of adult regulatory T cells (CD45RA(-) and GITR(+)) enabling suppression of polyclonal responses. We conclude that activation of self-reactive T cells in normal healthy individuals is prevented by the presence of self-antigen-specific CD25+ regulatory T cells and that the majority of these cells mature after birth.

Ambient air quality and occurrence of multiple sclerosis relapse

Infectious viruses and bacteria can trigger multiple sclerosis (MS) exacerbations. Seasonally changing concentrations of ambient air pollutants are known to predispose to transmissible infections, to induce systemic immune responses and to enhance existing peripheral inflammation. Ambient air quality and monthly MS relapse occurrence in south-western Finland were compared by multivariate logistic regression. The odds ratio of the risk of a relapse onset was over fourfold (4.143, p < 0.001) when the concentration of inhalable particulate matter (PM(10)) was at the highest quartile. Inhalable airborne particulate matter concentrations were connected to relapse occurrence. Poor air quality may enhance the seasonal changes in MS relapse occurrence by an increased susceptibility to transmissible infections.

Antibiotic prescription practices, consumption and bacterial resistance in a cross section of Swedish intensive care units

BACKGROUND

The purpose of this work was to study usage of antibiotics, its possible determinants, and patterns of bacterial resistance in Swedish intensive care units (ICUs).

METHODS

Prospectively collected data on species and antibiotic resistance of clinical isolates and antibiotic consumption specific to each ICU in 1999 were analyzed together with answers to a questionnaire. Antibiotic usage was measured as defined daily doses per 1000 occupied bed days (DDD1000).

RESULTS

Data were obtained for 38 ICUs providing services to a population of approximately 6 million. The median antibiotic consumption was 1257 DDD1000 (range 584-2415) and correlated with the length of stay but not with the illness severity score or the ICU category. Antibiotic consumption was higher in the ICUs lacking bedside devices for hand disinfection (2193 vs. 1214 DDD1000, p=0.05). In the ICUs with a specialist in infectious diseases responsible for antibiotic treatment the consumption pattern was different only for use of glycopeptides (58% lower usage than in other ICUs: 26 vs. 11 DDD1000,P=0.02). Only 21% of the ICUs had a written guideline on the use of antibiotics, 57% received information on antibiotic usage at least every 3 months and 22% received aggregated resistance data annually. Clinically significant antimicrobial resistance was found among Enterbacter spp. to cephalosporins and among Enterococcus spp. to ampicillin.

CONCLUSIONS

Availability of hand disinfection equipment at each bed and a specialist in infectious diseases responsible for antibiotic treatment were factors that correlated with lower antibiotic consumption in Swedish ICUs, whereas patient-related factors were not associated with antibiotic usage.

Link between the X4 phenotype in human immunodeficiency virus type 1-infected mothers and their children, despite the early presence of R5 in the child

Coreceptor use was determined for human immunodeficiency virus type 1 (HIV-1) isolates of various subtypes from 11 women during pregnancy and their infected children. Isolates from peripheral blood mononuclear cells (n=79) and from plasma (n=59) were available. The clinical and immunological stages of HIV-1 infection were recorded. Coreceptor use was tested on human cell lines expressing CD4 and different chemokine receptors. The R5 virus predominated, and only 9 isolates from 2 mothers used CXC chemokine receptor 4. All children carried the R5 virus at the time of diagnosis of HIV-1 infection. In 2 children of mothers carrying the X4 virus, the virus switched from R5 to X4 or to R5X4 by age 18 months (child no. 9) and age 48 months (child no. 10), whereas no children followed up to a similar age whose mothers were carrying the R5 virus experienced such a switch (P=.048). This points to a link between the presence of X4 virus in the mother and the emergence of X4 virus in her child.

Effect of budesonide enema on remission and relapse rate in distal ulcerative colitis and proctitis

BACKGROUND

Glucocorticosteroid enemas are equally effective as 5-ASA enemas in the treatment of active distal ulcerative colitis (UC). With the introduction of budesonide, the risk of systemic side effects may be reduced. We investigated whether budesonide enema, 2 mg/100 ml, administered twice daily (b.i.d.) could increase the remission rate in comparison with the once daily (o.d.) standard regimen. Furthermore, we evaluated whether 2 mg budesonide enema, given twice weekly, could have a relapse preventing effect.

METHODS

149 patients with active distal UC were treated in a controlled, double-blind multicentre study with two parallel groups: placebo enema in the morning and budesonide enema in the evening (i.e. 2 mg/day) or budesonide enema b.i.d. (i.e. 4 mg/day) until remission (absence of clinical symptoms and endoscopic healing) or at most 8 weeks. Patients in remission were randomized to either budesonide enema or placebo enema twice weekly for 24 weeks or until relapse.

RESULTS

The remission rates at 4 weeks were 33% for o.d. and 41% for b.i.d. regimens (NS) and correspondingly 51% and 54% at 8 weeks (NS). The b.i.d. group had an increased frequency of impaired adrenal function, 32% versus 4.8% (P = 0.001). The relapse rates during maintenance treatment with budesonide enema and placebo were 15% versus 24% after 8 weeks, 31% versus 27% after 16 weeks and 41% versus 51% after 24 weeks (NS).

CONCLUSION

Budesonide enema 2 mg o.d. appears to be the optimal dosage in active distal UC. We could not show that budesonide enema twice weekly is sufficient to maintain remission.

HLA class II markers and clinical heterogeneity in Swedish patients with primary biliary cirrhosis

Genetic susceptibility to PBC can, at least in part, be ascribed to the major histocompatibility complex. The relevance of immunogenetic markers for the clinical presentation and course, however, is unclear. Thus, the aim of this study was to investigate the contribution of HLA class II genes to susceptibility, clinical presentation and course of disease in PBC patients. HLA genotyping for HLA-DRB1, -DQB1 and -DPB1 was carried out in a total of 99 Swedish PBC patients and 158 controls. Clinical parameters including epidemiologic variables, signs and symptoms of PBC-related liver disease and histologic data were collected and analyzed in 92 patients at study entry and at follow-up five years later. Significant clinical heterogeneity was seen among PBC patients upon study entry. Although a significant disease association was seen for HLA DRB1*08 and DQB1*0402, immunogenetic markers identified neither a particular subset of patients nor an association with the clinical course of the disease. HLA-DRB1*08 and DQB1*0402 provide the strongest immunogenetic influence in PBC. However, this association is not restricted to any particular, clinically defined subgroup of patients and it is not predictive for the course of the disease.

Coreceptor change appears after immune deficiency is established in children infected with different HIV-1 subtypes

Change of HIV-1 coreceptor use has been connected to progression of disease in children infected with HIV-1, presumably subtype B. It has not been possible to discern whether the appearance of new viral phenotypes precedes disease development or comes as a consequence of it. We studied the evolution of coreceptor use in HIV-1 isolates from 24 vertically infected children. Their clinical, virological, and immunological status was recorded and the env V3 subtype was determined by DNA sequencing. Coreceptor use was tested on human cell lines, expressing CD4 together with CCR5, CXCR4, and other chemokine receptors. The children carried five different env subtypes (nine A, five B, four C, three D, and one G) and one circulating recombinant form, CRF01_AE (n = 2). Of the 143 isolates, 86 originated from peripheral blood mononuclear cells (PBMCs) and 57 originated from plasma, received at 90 time points. In 52 of 54 paired plasma and PBMC isolates the coreceptor use was concordant. All 74 isolates obtained at 41 time points during the first year of life used CCR5. A change from use of CCR5 to use of CXCR4 occurred in four children infected with subtype A, D, or CRF01_AE after they had reached 1.5 to 5.8 years of age. There was a significant association with decreased CD4+ cell levels and severity of disease but, interestingly, the coreceptor change appeared months or even years after the beginning of the immunological deterioration. Thus CXCR4-using virus may emerge as a possible consequence of immune deficiency. The results provide new insights into AIDS development in children.

GB virus C/hepatitis G virus infection in patients investigated for chronic liver disease and in the general population in southern Sweden

Serum samples from patients referred for liver biopsy for investigation of suspected chronic liver disease (n = 286) and from healthy middle-aged volunteers (n = 445) were analyzed for markers of exposure to GB virus C/hepatitis G virus (GBV-C/HGV), hepatitis B virus and hepatitis C virus. GBV-C/HGV analyses included GBV-C/HGV PCR for detection of viremia and GBV-C/HGV enzyme-linked immunosorbent assay for anti-GBV-C/HGV E2 antibodies. Liver biopsies were re-evaluated by a hepatopathologist. GBV-C/HGV markers were detected in 97/286 (34%) patients (GBV-C/HGV RNA = 26; anti-GBV-C/HGV E2 antibodies = 74) compared to 86/445 (19%; p < 0.0001) controls (GBV-C/HGV RNA = 7, anti-GBB-C/HGV E2 antibodies = 79). A significantly higher proportion of GBV-C/HGV-exposed subjects in the patient group were viremic compared to controls (27% vs. 8.1%; p = 0.0015). GBV-C/HGV markers were more commonly found in patients with chronic hepatitis B and C. In patients with GBV-C/HGV viremia, a higher occurrence of bile duct degeneration was detected than in non-viremic patients. Markers of GBV-C/HGV infection were over-represented among patients investigated for chronic liver disease, and ongoing GBV-C/HGV viremia was more common in this group than in controls. Apart from a higher prevalence of bile duct degeneration in viremic patients, infection with GBV-C/HGV did not confer any specific histological characteristics.

Effects of differently oxidized LDL on the expression of pro-inflammatory molecules in human monocytes in vitro

The oxidation of low-density lipoprotein (LDL) is thought to be a major contributor to the development of atherosclerosis and considerable evidence has accumulated showing that oxidized LDL (ox LDL) induces cell damage and pro-atherogenic events. However, evidence that oxidized LDL directly causes atherosclerosis is lacking. We studied whether native and enzymatically or chemically ox LDL at concentrations of 5 and 100 microg/mL is cytotoxic to or promotes pro-atherogenic activation of human primary monocytes in culture. Both types of ox LDL (100 microg/mL), but not native LDL added to monocytes for 24 h significantly diminish DNA synthesis and increase cell death. In addition, both preparations of ox LDL inhibit cytokine and metalloproteinase production, diminish cellular oxygen consumption and induce PPAR gamma expression. Enzymatically ox LDL, but not LDL oxidized by copper sulfate, also increases the monocyte metabolic rate and induces intracellular lipid accumulation. Low concentrations of either preparation of oxidized and native LDL did not show significant effects on all parameters measured. These data establish a direct link between ox LDL concentration and cytotoxicity and suggest that oxidation by copper of the lipid moiety in LDL and of the protein moiety by enzyme creates ox LDL, which can damage monocytes without release of pro-inflammatory molecular species. In contrast to native and enzymatically ox LDL, copper ox LDL does not induce intracellular lipid accumulation. Differently oxidized LDL molecules may exert distinct effects in lesion development in atherosclerosis.

Atorvastatin activates PPAR-gamma and attenuates the inflammatory response in human monocytes

OBJECTIVE

To investigate the ability of statins to activate the nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR-gamma) in primary human monocytes in culture.

MATERIALS AND METHODS

Human peripheral monocytes were incubated with atorvastatin (0.1-10 micromol/1) for up to 24 hours. PPAR-gamma expression was analysed by electrophoretic mobility shift assay. Pro-inflammatory cytokines were measured by enzyme-linked immunosorbent assays, and oxygen consumption was determined polarographically with a Clark-type oxygen electrode.

RESULTS

We found that atorvastatin activates PPAR-gamma and inhibits the production of tumour necrosis factor-alpha up to 38% (p < 0.05), monocyte chemoattractant protein-1 up to 85% (p < 0.05), and gelatinase B up to 73% (p < 0.05), in a concentration-dependent manner. Moreover, atorvastatin shows concentration-dependent inhibition of cellular oxygen consumption up to 41%.

CONCLUSIONS

These findings contribute to the growing knowledge of the anti-inflammatory effects of statins, and have led us to the suggestion that statins may control inflammatory responses by the regulation of intracellular lipid homeostasis.

Short and long term outcome of severe acute pancreatitis

OBJECTIVE

Between 1985 and 1994, 883 cases of acute pancreatitis were treated in Malmö, Sweden (population 233,000). The purpose of this study was to report the short- and long-term outcome of the 79 cases that were severe, according to the Atlanta classification.

DESIGN

Retrospective and follow-up study a median time of 7 years since the attack.

SETTING

University hospital, Sweden.

SUBJECTS

79 patients with severe acute pancreatitis.

MAIN OUTCOME MEASURES

Mortality, cause of death, organ failure, local complications, surgical procedures, mortality since the attack, and endocrine and exocrine dysfunction.

RESULTS

Twenty-one patients died from their attack. Organ failure was the predominant cause of death in the 13 patients who died during the first 10 days after admission, whereas infection was the most common cause of death in patients who died later. Mortality was low under the age of 60 and increased with age. Organ failure developed in 72 patients. Twenty-four patients developed pancreatic necrosis or abscesses and 18 patients were treated by necrosectomy and open or closed drainage. At follow-up, 13 patients had died, 2 from pancreatic carcinoma. 35 patients were included in the follow-up survey. 15 of these had diabetes and an additional 4 had impaired glucose tolerance. 9 patients had signs of severe exocrine dysfunction.

CONCLUSIONS

There was a high incidence of endocrine and exocrine dysfunction together with, in many patients, ongoing social problems related to chronic alcoholism several years after an attack of severe acute pancreatitis.

Future development of general internal medicine: a Swedish perspective

Over the past decade, the demands on internal medicine have increased markedly, partly due to an increasing number of elderly patients with multiple diseases. About half of all the cases coming into the emergency units of Swedish hospitals are related to internal medicine, while planned admissions account for only 10% of in-patient care. In our opinion, the fundamental cause of the strained situation in the health care service today is the fact that the emergency care responsibility of internal medicine is not clearly delimited. This means that the specialty must attend to problems in health care that the other health and sick-care services cannot cope with. Furthermore, an overly extensive division of the discipline of internal medicine into subspecialties can lead to inferior treatment of elderly patients with multiple diseases, as well as to increased costs. We believe that an umbrella organisation with overall management of independent subspecialties would make it possible to meet the increased need for internal medicine in a flexible way. In addition, internal medicine could widen its area of responsibility in the border region to surgery, while the demarcation to other specialties in the emergency unit, including primary care, is already very clear today, and should remain so.

C-terminal fragment of alpha1-antitrypsin activates human monocytes to a pro-inflammatory state through interactions with the CD36 scavenger receptor and LDL receptor

Monocyte scavenger receptor, CD36 has been implicated in the pathogenesis of atherosclerosis as a major oxidised LDL receptor mediating lipid accumulation and foam cell formation. Previously, we found that treatment of monocyte cultures with the carboxyl terminal fragment of alpha1-antitrypsin (C-36) increases lipid binding and uptake, induces LDL receptor mRNA and CD36 receptor protein expression, and also significantly increases production of pro-inflammatory molecules. To assess the role of the CD36 receptor in proatherogenic monocyte activation by the C-36 fragment, we tested whether specific anti-CD36 receptor antibodies would block the effects of C-36 on monocyte activation. We find that pre-incubation of cells with anti-LDL and anti-CD36 receptor antibodies (10 microg/ml) blocks binding of 125I-C-36 by about 50%. Similarly, cells pre-incubated with oxidised LDL or native LDL at concentrations from 2.5 to 10 microg/ml showed a loss of 125I-C-36 binding (up to 49 and 57%) and uptake (up to 47 and 59.8%), respectively. In parallel experiments, monocytes were first incubated for 1 or 6 h with anti-CD36 antibodies (10 microg/ml) prior to adding C-36 peptide. Anti-CD36 antibodies suppressed C-36-induced production of gelatinase B, monocyte chemoattractant protein-1, interleukin-6 and cellular oxygen consumption to control levels, whereas levels of TNFalpha were unaffected. In contrast, saturation of LDL receptors with excess of anti-LDL (20 microg/ml) significantly inhibited C-36 induced TNFalpha levels. Results indicate that the C-36 peptide binds to both LDL and CD36 scavenger receptors which involves selective upregulation of pro-inflammatory molecules and activation of the respiratory burst in human monocytes. This also supports important roles for CD36 and LDL receptors in atherogenesis and suggests that blockade of CD36 receptor can be protective in pro-inflammatory activation of human monocytes.

Chronic infusion of nicotine can increase operant self-administration of alcohol

Effects of nicotine, administered by continuous infusion via osmotic minipumps, were studied on the operant self-administration of alcohol by rats, using a variable interval (15 s) schedule, and measuring the acquisition, maintenance, extinction and reinstatement of responding for alcohol. Doses of nicotine of 0.25, 1.25 and 7.5 mg/kg/24 h had no significant effects on the maintenance of responding for alcohol, but 5 mg/kg/24 h nicotine resulted in a significant increase in responding on the lever delivering the reward when water was substituted for the alcohol, indicating delayed extinction of responding. During infusion of 2.5 mg/kg/24 h nicotine, responding was significantly greater over the "sucrose-fading" training sessions, during acquisition of responding, when mixtures of alcohol and sucrose were provided as reward. When minipumps infusing 2.5 mg/kg/24 h nicotine were implanted after the alcohol responding had been acquired, the responding for alcohol increase during the first week of nicotine infusion, but corresponding nicotine infusion doses of 0.25, 1.25 and 7.5 had no significant effects. The results indicate that nicotine can increase operant responding for alcohol and this is crucially dependent on the dose of nicotine and the time of testing. The results have implications for the frequently encountered dependence on the combination of alcohol and nicotine.

Fibrillogenic C-terminal fragment of alpha-1-antitrypsin activates human monocytes via oxidative mechanisms

Production of alpha-1-antitrypsin by human monocytes is an important factor in controlling tissue damage by proteases in the microenvironment of inflammation. Increases of four- to eightfold in levels of native and fragmented forms of alpha-1-antitrypsin have been detected in inflammatory loci in vivo. In this study we have extended our previous observation that the carboxyl-terminal peptide (C-36) of alpha-1-antitrypsin produced by specific proteinase cleavage, when added in its fibrillar form at concentrations of 5 microM or more to monocytes in culture, induces cytotoxic effects. Experiments with synthetic amyloid-forming peptides suggest fibril cytotoxicity to be mediated via a common oxidative stress mechanism. We undertook to determine whether C-36 fibril cytotoxicity also involves this common pathway. Monocytes stimulated with C-36 fibrils for 1 h showed significant elevation in monocyte chemoattractant protein-1 expression, induced reduced nicotinamide-adenine dinucleotide phosphate oxidase activity, increased intracellular lipid peroxidation, altered mitochondrial membrane potential, and increased cytosolic cytochrome c and caspase-3 activity. Treatment of monocytes with C-36 fibrils after 24 h also resulted in increased cytosolic cathepsin D activity, suggesting that lysosomes may also be destabilized over longer periods of time. In contrast, native alpha-1-antitrypsin only showed concentration and time-dependent effects on chemoattractant protein-1 expression, and these appear to be independent of oxidative stress. These results indicate that the cytotoxicity of the fibrillar fragment is mediated via oxidative mechanisms and support important multiple roles for native and also for cleaved forms of alpha-1-antitrypsin in monocyte recruitment and activation during inflammatory processes such as atherosclerosis.

[Continuing should be a part of the clinical reality. Courage is required to see both the strong and the weak sides of the professional situation]

Continuing professional development (CPD) is a joint responsibility of the individual physician and the employer. CPD should focus on identification and documentation of the learning needs of the individual, based on professional demands. Reflection, feedback and evaluation of the results are central elements of the process. Efficient learning demands active participation; modern information technology is now becoming more widely available.

HIV-1 in placentas of untreated HIV-1-infected women in relation to viral transmission, infectious HIV-1 and RNA load in plasma

The presence of HIV in the placenta was analysed in relation to virological and immunological factors and vertical transmission of HIV in 39 pregnancies between 1989 and 1993 among 37 HIV-1-infected women without zidovudine prophylaxis. HIV-1 was detected in 12 of 37 (31%) placentas by immunohistochemistry and in 3 of 18 by PCR. Altogether 14/39 (36%) placentas bore evidence of HIV-1 infection, although there was no relation with the outcome of HIV infection in the child. Neither was there a relation between placental infection and either CD4 cell counts or HIV-1 RNA levels. However, HIV-1 was isolated from plasma in 20 of 39 (50%) pregnancies, which was inversely related to the presence of HIV in the placenta. When HIV-1 was identified in the placenta, HIV-1 was isolated from plasma in 3/14 (21%) pregnancies, vs 17/25 (68%) when it was not (p = 0.01), with a relative risk of having a placenta positive for HIV of 3.9 in pregnancies with a negative plasma HIV isolation. This inverse relation may point to differences in tropism between HIV-1 in placenta and plasma. The results show that the placental barrier prevents HIV transmission, irrespective of whether HIV enters the placenta or not.

Broad Spectrum of Time of Detection, Primary Symptoms and Disease Progression in Infants with HIV-1 Infection

The relationship between time of HIV-1 detection, appearance of symptoms and disease progression was studied in all 24 HIV-1-infected infants from a cohort of 117 children who were born to HIV-1-infected mothers and monitored from birth. HIV isolation from plasma and mononuclear cells, HIV-1 DNA PCR (polymerase chain reaction) and, retrospectively, a quantitative assay for HIV-1 RNA were used for virus detection. Two infants possibly exhibited a symptomatic primary HIV infection. More children with than without symptoms during the first year of life progressed to immunological class 3 (P=0.013) and to AIDS or death (P=0.003) during follow-up. HIV-1 was detected within 4 days of age in 4 of 16 infants: 3 of them became symptomatic within 1 year, as did 6 of the remaining 12 infants (not statistically significant). All four infants in whom virus was detected within 4 days of age progressed to severe immunosuppression, compared to 6 of 14 in whom the virus detection test was initially negative prior to the first positive result (n.s.). Two children with previous repeatedly negative HIV detection tests were diagnosed with HIV-1 infection at 8 and 9 months, respectively. Repeated blood sampling is needed for the diagnosis of HIV-1 infection in perinatally exposed infants, and virus detection tests for exclusion of HIV-1 infection must be used with caution.

Clinical spectrum of hepatitis C-related liver disease and response to treatment with interferon and ribavirin in haemophilia or von Willebrand disease

Our aim was to evaluate the severity of liver disease resulting from chronic hepatitis C in haemophilia or von Willebrand disease and the efficacy of 6 months treatment with interferon alpha and ribavirin. Fifty-five liver biopsies were performed in 43 patients without any bleeding complications, as seen with ultrasound immediately after the biopsy and 48 h thereafter. Histological changes were mild, with low scores for both inflammation and fibrosis, in spite of long exposure to blood products (mean 27 years). Two patients had compensated cirrhosis. Thirty-five out of 39 included patients completed study treatment. Hepatitis C virus (HCV)-RNA was negative in 77% (30/39) of patients at the end of treatment, and 36% (14/39) achieved a complete sustained response at follow-up 6 months after treatment. Treatment failure was more frequent in patients with virus genotype 1 compared with non-1 (P = 0.0003). The response rate correlated well with that of non-haemophilic patients. In summary: (1) liver biopsy was safe with our regimen; (2) liver disease in our patients was usually mild and had a slow progress; (3) only HCV genotype 1 predicted treatment failure; (4) our treatment results agreed with those from non-haemophilic patients.

Warning! Suctioning. A lung model evaluation of closed suctioning systems

BACKGROUND

Closed system suctioning, CSS, has been advocated to avoid alveolar collapse. However, ventilator manufacturers indicate that extreme negative pressure levels can be obtained during closed system suctioning, impeding the performance of the ventilator.

METHODS

Suctioning with a 12 or 14 Fr catheter with a vacuum level of -50 kPa was either performed with an open technology or a CSS, where the catheter is introduced through a tight-fitting connection through the endotracheal tube, EYT. The lung model was ventilated with a Servo 900C or 300 ventilator with an I:E ratio of 1:2, 1:1 and 2:1 and extrinsic positive end-expiratory pressure (PEEP) at 0 or 10 cm H20. Respiratory volumes and alveolar pressure were measured at the lung model alveolus.

RESULTS

The initial suctioning flow was >40 l/min with a 14 Fr catheter. When inserting the catheter through a no. 7 ETT, PEEP rose from 11 to 23 cm H2O during volume control ventilation with an I:E ratio 1:1. During suctioning the alveolar pressure fell to 10 cm H2O below the set PEEP level. CSS during pressure control ventilation had fewer effects. Low tidal volumes, inverse I:E ratio and secretions in the tube resulted in pressures down to -92 cm H2O.

CONCLUSION

CSS should not be used in volume control ventilation due to risk of high intrinsic PEEP levels at insertion of the catheter and extreme negative pressures during suctioning. Pressure control ventilation produces less intrinsic PEEP effect. The continuous positive airway pressure (CPAP) mode offers the least intrinsic PEEP during insertion of the catheter and least sub-atmospheric pressure during suctioning.

Effects of Noninhibitory α-1-Antitrypsin on Primary Human Monocyte Activation in Vitro

A major function of alpha-1-antitrypsin (AAT) is the inhibition of overexpressed serine proteinases during inflammation. However, it is also known that the biological activity of AAT is affected by chemical modifications, including oxidation of the reactive-site methionine, polymerization, and cleavage by unspecific proteases, all of which will result in AAT inactivation and/or degradation. All inactive forms of AAT can be detected in tissues and fluids recovered from inflammatory sites. To test for a possible link between the inflammation-generated, noninhibitory, cleaved form of AAT and cellular processes associated with inflammation, we studied the effects of this form at varying concentrations on human monocytes in culture. We found that cleaved AAT at concentrations ranging between 1 and 10 microM in monocyte cultures over 24 h induces elevation in monocyte chemoattractant protein-1 (MCP-1) and pro-inflammatory cytokines such as TNFalpha and IL-6 and also increases production of interstitial collagenase (MMP-1) and gelatinase B (MMP-9), members of two different classes of matrix metalloproteinase. Moreover, monocytes stimulated with higher doses of cleaved AAT show an increase in cellular oxygen consumption by about 30%, while native AAT under the same experimental conditions inhibits oxygen consumption by about 50%. These results indicate that the cleaved form of AAT may play a role in monocyte recruitment and pro-inflammatory activation during inflammatory processes, and also suggest that changes in structure occurring upon AAT cleavage could alter its functional properties with potential pathological consequences.

Pravastatin down-regulates inflammatory mediators in human monocytes in vitro

There is experimental evidence that pravastatin, which is designed to inhibit the rate-limiting enzyme of cholesterol synthesis, can affect cell metabolism and proliferation. We therefore studied the effects of pravastatin on the generation of inflammatory mediators in non-stimulated and stimulated primary human monocytes in vitro. In our experimental model, pravastatin induced a dose-dependent inhibition of monocyte cholesterol synthesis (up to 67%), up-regulation of low density lipoprotein receptor mRNA (by about 35%) and reduction in intracellular cholesterol accumulation. In parallel, exposure of non-stimulated monocytes to various doses of pravastatin resulted in inhibition of monocyte chemoattractant protein-1 protein expression (up to 15-fold), reduction of tumour necrosis factor alpha (TNF-alpha) levels (up to 2.4-fold) and a total loss of metalloproteinase-9 activity in stimulated cells. Pravastatin at concentrations of 5, 100 and 500 microM caused an inhibition of TNF-alpha-induced cellular oxygen consumption from 2. 4- to 5.5-fold. These data extend the findings of potential anti-inflammatory actions of statins and also suggest the possibility for pravastatin use in a broader spectrum of inflammatory situations.

Production and characterization of novel anti-prostate-specific antigen (PSA) monoclonal antibodies that do not detect internally cleaved Lys145-Lys146 inactive PSA

BACKGROUND

The nature of free, uncomplexed prostate-specific antigen (PSA) in the circulation is still unknown. In this study, we developed novel anti-PSA antibodies using PSA produced by a metastasized cancer cell line, LNCaP, as an immunogen.

METHODS

Hybridoma cell lines were screened with different methods that aimed at finding antibodies specific for the forms of free PSA produced by LNCaP cell line. Obtained antibodies were further studied for their characteristics related to previously characterized monoclonal antibodies.

RESULTS

Numerous anti-PSA antibodies were obtained, of which four represented unique epitopes previously unrecognized by us. One free-PSA-specific antibody was bound to PSA on two distinct epitopes, and one antibody was bound to the carboxyl-terminal peptide of PSA. Two antibodies were found to bind to the peptide sequence adjacent to the internal cleavage site Lys145-Lys146. These antibodies failed to recognize internally cleaved PSA at Lys145-Lys146. We could not find anti-proPSA antibodies despite the fact that LNCaP PSA contained more than one-half of the zymogen form of PSA.

CONCLUSIONS

We report, for the first time, novel anti-PSA antibodies that do not recognize internally cleaved PSA at Lys145-Lys146 and thus are specific for intact, unclipped PSA.

Basilar artery occlusion in a child: "clot angioplasty" followed by thrombolysis

Basilar artery occlusions are rare but have a very poor prognosis. Intra-arterial thrombolysis may produce recanalization and better clinical outcome. A short delay between the onset of symptoms and thrombolysis is considered essential for successful recanalization and for the smallest possible risk of haemorrhagic complications. We present a case of basilar artery occlusion in an 8-year-old child, which was treated by "clot angioplasty" followed by intra-arterial thrombolysis. Thirty hours after progressive alteration of consciousness, speech disturbances and left arm paresis, the child became comatose with decerebrate rigidity. A CT scan showed parenchymal ischaemic lesions. Angiography (performed 36 h after the onset of symptoms) showed a total occlusion of the basilar artery. A clot angioplasty was performed by placing a balloon catheter within the thrombus and inflating it several times in the occluded segment of the basilar artery. Thrombolysis was then performed through the balloon catheter. The basilar artery was only partially recanalized at the end of the procedure, but the perforating arteries of the brain stem had reappeared on angiography. Three months later the child had completely recovered to a normal clinical status. In conclusion, the very poor natural prognosis of basilar artery occlusion requires aggressive management. Recanalization of the basilar artery may be performed even late after the onset of symptoms. Clot angioplasty allows partial recanalization, which may increase the efficiency of thrombolysis.

Prevalence and clinical spectrum of chronic viral hepatitis in a middle-aged Swedish general urban population

BACKGROUND

Although abundant data are available regarding the prevalence of chronic hepatitis B or C virus (HBV, HCV) among both blood donors and patients with liver diseases, corresponding data for the general population are scarce. Accordingly, this study was designed to investigate the prevalence and clinical spectrum of HBV and HCV in a general Swedish middle-aged urban population.

METHODS

Demographic data and blood samples were collected from subjects enrolled in a prospective study of cancer development in the city of Malmö (population 250,000). The participation rate in the preliminary examination was 46.2%. From 12,445 individuals born between 1926 and 1945 and included in the study, a statistically representative subsample of 6103 persons was selected. Blood samples were available from 5533 of these. The mean age of the subjects in the series was 58.5 +/- 5.9 years, and 59% were women. The HBV markers used were anti-HBc and HBsAg. HCV antibodies were detected with a third generation anti-HCV ELISA, followed by immunoblotting (RIBA 3) if the test was positive. Immunoblot-reactive samples were analysed for HCV-RNA by polymerase chain reaction and genotyped. In all patients with signs of chronic HBV or HCV, epidemiological data were evaluated and liver biopsies obtained.

RESULTS

Of the series as a whole (n = 5533), 4.2% (n = 211) tested positive for anti-HBc and 0.2% (n = 10) for HBsAg. RIBA 3 analysis showed 0.37% (18/5533) to be anti-HCV-positive, of whom 83% (15/18) were HCV-RNA-positive. Apart from two (both from HBsAg carriers) with normal histology, all liver biopsies manifested various degrees of inflammation and fibrosis. Among anti-HCV-positives, median grade was 6 and median stage 1 (Knodell score).

CONCLUSION

The prevalence of both chronic HBV and HCV is low in the Swedish general urban middle-aged population. Nonetheless, the long-term effects on the population and the health care system may be significant.

[Mother-to-child transmission of HIV infections. Antiviral agents and Cesarean section reduce the risk of transmission]

There has been a substantial decrease in maternal-infant transmission of HIV in many European and North American countries during the past five years, from 15-25 per cent to approximately 5%. Reasons include the prophylactic administration of zidovudine to mother and child, more effective treatment strategies leading to decreased viral load during pregnancy, and increased use of elective Caesarean section. In developing countries however, the vertical transmission rate of HIV is still high at 25-40 per cent. Simpler and less expensive prophylactic regimens, such as nevirapine to mother and child at delivery and after birth, respectively, have raised hope. Drug resistance and the risk of adverse effects of antiretroviral drugs on the child are threats to the prevention of mother-to-infant transmission of HIV.

The carboxyl-terminal fragment of alpha1-antitrypsin is present in atherosclerotic plaques and regulates inflammatory transcription factors in primary human monocytes

alpha1-Antitrypsin (AAT) serine proteinase inhibitor is found in most biological fluids, diffuses into most tissues, and is an important factor in controlling tissue damage by proteases in inflammatory diseases such as atherosclerosis. We have previously reported that the C-terminal fragment (C-36) generated during the cleavage of AAT by proteinases forms amyloid fibrils which have biological effects unrelated to precursor functions. Here we show that the C-36 fragment is present in atherosclerotic plaques, particularly within the fibrous cap at the base of the lipid core. We also found that human monocyte stimulation with C-36 fibrils led to a strong activation of both peroxisome proliferator-activated receptors alpha and gamma (PPARalpha and PPARgamma) at 1, 2, and 18 h of cell culture. A parallel increase in the intracellular lipid accumulation was also observed. Furthermore, stimulation of monocytes with C-36 for 18 h led to activator protein-1 (AP-1) and nuclear factor-kappaB (NF-kappaB) activation. These data for the first time demonstrate the peptide of AAT as a component of atherosclerotic plaques and as a novel activator of PPARalpha, PPARgamma, NF-kappaB, and AP-1 in cultured monocytes. Taken together, the effects of the peptide represent a new mechanism of monocyte activation that may be of importance not only in atherogenesis, but also in other inflammatory processes.

Increased presence of cells containing transforming growth factor alpha (TGF-alpha) in ulcerative colitis, both during active inflammation and in remission

OBJECTIVE

Patients with extensive and long-standing ulcerative colitis have an increased risk of developing colorectal cancer and sub-epithelial fibrosis. The polypeptide transforming growth factor alpha (TGF-alpha) has mitogenic effects and it is believed that local overproduction may result in tumour formation and fibrosis.

DESIGN

In the present study, we correlated the presence of TGF-alpha in ulcerative colitis with the degree of inflammation and with dysplasia.

METHODS

Sixty two patients were investigated, 46 with ulcerative colitis (16 with active inflammation and 20 in remission, 10 with dysplasia of the colon), and 16 controls with normal colonoscopy and without a history of colitis. There were no overlaps between the subgroups. Tissue sections from colonic biopsies were examined and TGF-alpha was detected by immunohistochemistry. TGF-alpha-containing cells were characterized by double-staining with antibodies to eosinophil cationic protein (ECP). An antibody (EG2) recognizing eosinophils with an activated phenotype was also used.

RESULTS

The median number of TGF-alpha-containing cells in the mucosa was 24 per mm2 (inter-quartile range 10-51) in controls, 186 per mm2 (73-245) in ulcerative colitis with active inflammation, 76 per mm2 (52-198) in remission, and 130 per mm2 (66-203) in areas of dysplasia. Double-staining for TGF-alpha and ECP revealed that most of the TGF-alpha-containing cells were eosinophils, and most had an activated phenotype as judged by staining with EG2.

CONCLUSIONS

The presence of TGF-alpha-containing cells in colonic mucosa is increased both in active inflammation and during remission in ulcerative colitis. Dysplasia is not associated with any significant increase in TGF-alpha-containing cells. The majority of TGF-alpha-containing cells are eosinophils with an activated phenotype. TGF-alpha released from these cells could be important for the development of complications seen in ulcerative colitis, such as cancer and fibrosis.

Involvement of the entire spinal cord and medulla oblongata in acute catastrophic-onset transverse myelitis in SLE

A 30-year-old Caucasian male with systemic lupus erythematosus suffered acute catastrophic-onset transverse myelitis. Two years earlier aseptic meningitis, another rare CNS lupus manifestation, had been diagnosed. MRI showed involvement of the medulla oblongata and the entire spinal cord. Therapy with intravenous high-dose methylprednisolone and intravenous cyclophosphamide is discussed.

Inflammatory bowel disease promotes venous thrombosis earlier in life

BACKGROUND

Patients with inflammatory bowel disease (IBD) may be at increased risk of having venous thromboembolism.

METHODS

Medical records from 1,253 IBD patients attending hospital care during the years 1987-97 were studied. These patients were recruited from a population of 340,000 inhabitants. Patients with verified venous thrombosis were characterized clinically, and blood samples were examined for coagulopathy including analyses of antithrombin, plasminogen, protein C, protein S, factor V, and prothrombin mutations. As control groups we used 99 patients with verified venous thrombosis and no history of IBD and 288 volunteers with no history of thrombosis.

RESULTS

The incidence of venous thrombosis was 1.5/1,000 IBD patients per year, which is comparable to the background population. The mean age was significantly lower in IBD patients than in non-IBD patients (53 versus 64 years, P= 0.0225). We found one patient with antithrombin deficiency but none with protein C, protein S, or plasminogen deficiency. Factor V mutation was as prevalent in IBD patients with thrombosis as in thrombotic non-IBD patients (27% versus 28%) and 3.0 times (95% confidence interval, 0.8-11.9) more frequent in IBD patients with thrombosis than in healthy controls. Prothrombin mutation was not detected in IBD patients with venous thrombosis.

CONCLUSION

We found no increased incidence of venous thrombosis in IBD patients compared with a background population. However, IBD patients had venous thrombosis earlier in life than non-IBD patients. Although factor V mutation may contribute to thrombosis, IBD acts as a trigger through mechanisms that still remain unexplained.

Anti-neutrophil cytoplasmic antibodies in patients with chronic liver diseases: prevalence, antigen specificity and predictive value for diagnosis of autoimmune liver disease. Swedish Internal Medicine Liver Club (SILK)

BACKGROUND

Anti-neutrophil cytoplasmic antibodies (ANCA) against proteinase 3 are diagnostic of Wegener's granulomatosis, but ANCA occur also in patients with other inflammatory disorders, such as ulcerative colitis, primary sclerosing cholangitis (PSC) and autoimmune hepatitis. As their predictive value for autoimmune liver disease remains unknown, we analysed the prevalence and antigen specificity of ANCA in patients with various chronic liver diseases (CLD).

METHODS

We studied sera from 100 patients with primary biliary cirrhosis (PBC), from 76 with PSC and from 279 with various CLD, consecutively drawn during a 5-year period at the time of liver biopsy. The ANCA were detected by indirect immunofluorescence (IIF) while the antigen specificity was characterized by ELISA by using lactoferrin, neutrophil elastase, cathepsin G and BPI (bactericidal/permeability increasing protein) as antigens.

RESULTS

In PBC, ANCA were detected by IIF in 39 patients (39%). The antigen reactivity by ELISA was lactoferrin in seven, elastase in 15, BPI in 20 and cathepsin G in four patients. Four patients had reactivity against more than one antigen. In PSC, IIF demonstrated ANCA in 49 patients (65%). The antigen reactivity was lactoferrin in 17, elastase in 14, BPI in 20 and cathepsin G in four patients. Twelve patients showed reactivity against more than one antigen. In CLD, ANCA were observed in sera from 55 patients (20%). Nineteen of 45 patients (42%) with autoimmune liver disease were ANCA positive versus 36/234 (15%) with non-autoimmune liver disease (P = 0.0002). Among IIF-positive patients, antibody reactivity against lactoferrin was noted in 14, elastase in 28, BPI in 25 and cathepsin G in five patients. Twenty-one patients had reactivity against more than one antigen. Elastase and BPI antibodies occurred more frequently in patients with autoimmune compared to non-autoimmune liver disease (P < 0.01).

CONCLUSIONS

Anti-neutrophil cytoplasmic antibodies are prevalent in patients with chronic liver diseases, but although they occur more frequently in patients with autoimmune liver disease their specificity and sensitivity for autoimmune liver disease is low. The predominant antigens are lactoferrin, elastase and BPI, but the correlation between IIF findings and ELISA reactivity against these antigens is weak.

Serum antibodies to Helicobacter hepaticus and Helicobacter pylori in patients with chronic liver disease

BACKGROUND

Bile tolerant helicobacter species such as H hepaticus and H bilis have frequently been reported to cause hepatitis in mice and other rodents.

AIMS

To investigate the possible pathogenic role of these and other helicobacter species in chronic liver disease in humans.

METHODS

Serum samples from 144 patients with various chronic liver diseases, 30 patients with primary sclerosing cholangitis (PSC), and 48 healthy blood donors were analysed for antibodies against H hepaticus murine strain CCUG 33637 and H pylori strain CCUG 17874. Cell surface proteins of H hepaticus were extracted by acid glycine buffer and used in an enzyme immunoassay (EIA) and immunoblot (IB).

RESULTS

56 of 144 (39%) patients with chronic liver diseases and six of 30 (20%) with PSC showed increased antibody concentrations in the H hepaticus EIA; in the H pylori EIA the numbers were 58% and 13% respectively. Compared with the healthy blood donors the antibody reactivity against the two helicobacter species was not increased (46% and 48% respectively). Patient serum samples retested by the H hepaticus EIA after absorption with sonicated H pylori cells remained positive in 12 of 37 (33%) serum samples. Distinct antibody reactivity to 55-65 kDa proteins was observed by H hepaticus IB, after the absorption step, and was considered specific for H hepaticus. These 12 serum samples were from patients with chronic alcoholic liver disease.

CONCLUSIONS

Antibodies to H hepaticus, often cross reacting with H pylori, occur frequently in patients with chronic liver diseases, with no clear cut relation to specific diagnostic groups. The pathogenic significance of these findings is not known.

Alpha1-antitrypsin deficiency may be a risk factor for duodenal ulcer in patients with Helicobacter pylori infection

BACKGROUND

Most individuals with Helicobacter pylori infection in Western countries have no evidence of peptic ulcer disease (PUD). We therefore assessed the PiZ deficiency variant of the major plasma protease inhibitor alpha1-antitrypsin (alpha1AT) as a risk factor for PUD in H. pylori-infected individuals.

METHODS

The cohort comprised 100 patients with endoscopically or surgically proven PUD (30 patients with duodenal ulcer (DU) and 70 patients with gastric ulcer (GU)) and 162 age- and sex-matched controls with PUD-negative endoscopic findings and no history of PUD. Plasma samples were screened for alpha1AT deficiency (PiZ) with an enzyme-linked immunosorbent assay (ELISA) and phenotyped by isoelectric focusing. H. pylori infection was evaluated with an IgG ELISA technique.

RESULTS

Among the 262 patients 17 (6.5%) were positive for the PiZ alpha1AT deficiency, a frequency of the same magnitude as in the Swedish general population (4.7%). Of the PiZ carriers 76% (13 of 17) had H. pylori antibodies compared with 61% (151 of 245) of the non-PiZ carriers (NS). The prevalence of DU tended to be higher in H. pylori-positive PiZ carriers than in non-PiZ carriers (15.4%, 4 of 26 versus 0 of 4). Furthermore, among patients with DU a high PiZ allele frequency (13.3%, 4 of 30) was found compared with the general population (4.7%) (odds ratio (OR), 3.2; 95% confidence interval (CI), 1.09-8.94; P = 0.02). All DU patients carrying the PiZ allele were positive for H. pylori. In addition, four of five PiZ carriers with H. pylori infection and PUD had DU.

CONCLUSIONS

The PiZ allele may be a contributing factor in the development of DU in H. pylori-positive individuals.

Fibrillar Alzheimer's amyloid peptide Abeta(1-42) stimulates low density lipoprotein binding and cell association, free radical production and cell cytotoxicity in PC12 cells

Amyloid forming peptides are known to disturb vital cellular functions and induce cell death. However, the mechanisms by which fibrillogenic peptides induce cytotoxic effects in various cells has not been established. In this study the effects on low density lipoprotein binding and uptake of fibrils of the Alzheimer's amyloid beta-peptide (Abeta(1-42)), which is known to play a central role in the pathogenesis of Alzheimer's disease, were investigated in pheochromocytoma PC12 cells. Fibrillar Abeta(1-42) at micromol concentrations increased low-density lipoprotein (LDL) binding and cell association by 460% and 200% respectively, and LDL degradation by about 62%. Approximately 49% and 34% of Abeta fibril stimulated LDL cell association and degradation was inhibited by anti-LDL receptor antibodies. The soluble form of Abeta had no effect on any of these measures of LDL metabolism. The observed increased glutathione reductase activity, DNA fragmentation (TUNEL assay) and decreased DNA synthesis ([(3)H] thymidine incorporation assay) in cells treated with Abeta(1-42) fibrils alone or together with LDL relative to controls, suggests that the interaction of fibrils with LDL receptors might be one possible pathway which contributes to fibril cytotoxicity.

Atherogenic properties of human monocytes induced by the carboxyl terminal proteolytic fragment of alpha-1-antitrypsin

Atherosclerotic plaques contain a significant number of macrophage foam cells and are associated with an inflammatory state. Inflammation induces the secretion from monocytes and other cells of cytokines, reactive oxygen species, proteinases and proteinase inhibitors among many other molecular species. AAT is prominent among the serine proteinase inhibitors and is an important regulator of leukocyte elastase and proteinase-3. It has been shown that the stable AAT-proteinase complex can upregulate AAT biosynthesis, and we have shown that the shorter, carboxyl terminal peptide (C-36) resulting from proteinase cleavage of AAT polymerizes, and in its fibrillar form alters cellular metabolism. To test for a possible link between the inflammation-generated C-36 peptide and cellular processes associated with atherogenesis, we have studied the effects of the fibrillar form of this peptide at varying concentrations on human monocytes in culture. We have found that fibrillar C-36 at concentrations of greater than or equal to 5 micromol/l in monocyte cultures for 24 h significantly increases LDL binding and uptake, upregulates LDL receptors, induces cytokine production and glutathione reductase activity, and upregulates AAT synthesis. The expression of CD36 protein, LDL Scavenger receptor, is also upregulated by fibrillar C-36 and native LDL in the presence of C-36-activated monocytes is more oxidized than with unactivated control monocytes. The majority of monocytes cultured for 24 h in the presence of C-36 fibrils were transformed morphologically into macrophages. These data establish a direct molecular link, mediated by C-36 peptide of AAT, between inflammation and the oxidation and accumulation of lipid in monocyte-derived macrophages. This may be important for an understanding of the events conducive to atherogenesis.

Human monocyte activation by cleaved form of alpha-1-antitrypsin involvement of the phagocytic pathway

Production of alpha-1-antitrypsin (AAT) by human monocytes is an important factor in controlling tissue damage by proteases in the microenvironment of inflammation. Increases, of four- to eightfold, in numbers of macrophages and levels of AAT and its cleavage fragments have been found in various inflammatory loci. We have found that the C-terminal peptide (C-36) of AAT, produced by specific proteinase cleavage when added in its fibrillar form at concentrations >/=5 microM to monocytes in culture for 24 h, significantly increases low density lipoprotein (LDL) binding and uptake, up-regulates levels of LDL receptors and also induces proinflammatory cytokine (interleukin-1, interleukin-6 and tumour necrosis factor alpha) production and glutathione reductase activity. Because it is known that various cells selectively internalize surface receptors and their ligands through receptor-mediated endocytosis via clathrin-coated pits, we tested whether antibodies raised against the clathrin heavy chain would block the effects of the fibrillar form of C-36 on human monocytes in culture. Addition of excess anti-(clathrin HC) with 10 microM fibrillar C-36 diminished the stimulatory effects of the latter on LDL binding, uptake and LDL receptor levels. In contrast, however, in the presence of anti-(clathrin HC), the potentially cytotoxic effects of fibrils, such as induction of cytokines, free radicals and cytosolic activity of cathepsin D, were much greater than those observed when cells were treated with fibrils alone. These results suggest that endocytosis is the pathway by which C-36 fibrils upregulate LDL receptors, and may be the natural mechanism for fibril clearance. We infer that human monocytes clear C-36 fibrils by a clathrin-dependent pathway, presumably endocytotic, and that loss of this pathway amplifies the cytotoxic effects of the fibrils by increasing their availability to other specific or nonspecific sites through which they exert their cytotoxic effects.