Sustained post-rituximab B-cell depletion is common in ANCA-associated vasculitis and is affected by sex and renal function

OBJECTIVE

Despite the increasing use of rituximab in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), it remains unclear what the optimal dosing is, especially for maintenance of remission. A deeper understanding of post-rituximab B-cell repopulation patterns may aid better-tailored treatment.

METHODS

This is a monocentric, retrospective study including ANCA-positive AAV patients receiving a single course of rituximab induction. CD19+ B cells were longitudinally monitored with flow cytometry. B-cell repopulation was defined as CD19+ >10 cells/μL.

RESULTS

Seventy-one patients were included, the majority with microscopic polyangiitis (75%), myeloperoxidase-ANCA positivity (75%) and with renal involvement (79%). During a median follow-up of 54 months since the first rituximab infusion, 44 patients (62%) repopulated B cells, with a median time to repopulation of 39 months (range 7-102). Patients experiencing B-cell depletion lasting longer than the overall median time to repopulation (39 months) exhibited a lower risk of flare and higher risk of serious infection. In multivariate Cox regression, higher estimated glomerular filtration rate (eGFR) [hazard ratio (HR) 1.84, 95% confidence interval (CI) 1.13-2.98 per 30 mL/min/1.73 m2 eGFR] and female sex (HR 2.70, 95% CI 1.37-5.31) were independent predictors of increased rate of B-cell repopulation.

CONCLUSION

A subset of AAV patients develop sustained post-rituximab B-cell depletion, which associates with reduced risk of flare and increased risk of serious infection in the long term. Preserved renal function and female sex are associated with faster B-cell repopulation. These observations further highlight the need to personalize immunosuppression to improve clinical outcomes.

FC061: Renal Function is a Major Determinant of B-Cell Repopulation Following Rituximab Induction in Anca-Associated Vasculitis

BACKGROUND AND AIMS

Rituximab is increasingly used to induce and maintain remission in ANCA-associated vasculitis (AAV). However, it remains unclear what the optimal dosing regimen is, especially in the setting of maintenance. Clinical trials have shown that vasculitis flares are unlikely as long as B-cell depletion in peripheral blood is sustained, with some evidence supporting a rituximab redosing strategy guided by B-cell-count monitoring. A better understanding of B-cell kinetics following rituximab treatment can facilitate personalized treatment approaches. This study aims to (1) describe B-cell repopulation in AAV patients treated with rituximab induction, and (2) identify clinical features predictive of B-cell repopulation.

METHOD

This is a single-centre, retrospective study, including AAV patients on no baseline immunosuppression who were treated with rituximab induction between December 2009 and March 2018 in the Nephrology Unit of Spedali Civili, Brescia. Only patients with available longitudinal B-cell monitoring for at least 6 months following rituximab were considered. B-cell counts were determined as CD19 + cells in peripheral blood using flow cytometry (Beckman Coulter Navios©).

B-cell repopulation following rituximab was defined as CD19 + cell count >10 cells/μL, with a documented CD19 + count ≤ 10 cells/μL within the preceding year. For each patient, CD19 + cell counts were followed up to the earliest event among the following: (1) B-cell repopulation, (2) retreatment with rituximab or other induction agents, or (3) most recent observation available.

Estimated glomerular filtration rate (eGFR) was calculated using the CKD-EPI equation. Flares were defined as active disease retreated with rituximab or cyclophosphamide and classified as major if one or more major items of the BVAS score v3 were present.

Predictors of time to B-cell repopulation were assessed using uni- and multivariate analysis with log-rank test and Cox proportional hazards regression, respectively.

RESULTS

The study cohort included 64 patients. The main clinical characteristics are summarized in Table 1. During a median follow-up of 33.4 months (range 7.5–101.7 months), B-cell repopulation was observed in 36 patients (56.2%). Median time from rituximab induction to B-cell repopulation was 39.8 months [95% confidence interval (95% CI) 33.8–69.7]. Gender, ANCA subtype, rituximab dose, steroid pulses, plasma exchange and methotrexate/azathioprine maintenance were not significantly associated with time to B-cell repopulation. In contrast, B-cell repopulation was significantly slower in patients who were older (median time to repopulation 51.6 months in patients ≥ mean age of 66.8 years old versus 33.9 months in < mean age; P = 0.044), who had microscopic polyangiitis (median 51.6 months), as opposed to granulomatosis with polyangiitis (median 33.9 months; P = 0.012) and who had lower eGFR at the time of rituximab (69.7 months in eGFR < median of 18.3 mL/min/1.73 m2 versus 28.4 months in eGFR ≥ median; P = 0.001, Figure 1). Of these three predictors, only eGFR remained significantly associated with time to B-cell repopulation in a multivariate Cox regression model (hazard ratio for B-cell repopulation in eGFR ≥ median: 2.74, 95% CI 1.31–5.72).

During sustained B-cell depletion, six vasculitis flares were observed, of which one was major (rise in creatinine > 30%) and the rest were minor (n = 4 worsening of urine abnormalities, n = 1 retro-orbital pain).

CONCLUSION

A substantial proportion of AAV patients treated with a single course of rituximab shows sustained B-cell depletion. Renal function emerged as the main independent predictor of B-cell repopulation, with delayed B-cell repopulation in people with kidney impairment. Only one major vasculitis flare was observed during sustained B-cell depletion. These data support the idea that longitudinal monitoring of B-cell counts can be a useful biomarker to guide rituximab dosing for maintenance in AAV, especially in patients with kidney impairment.

SARS-CoV-2 infection in dialysis and kidney transplant patients: immunological and serological response

Background

Dialysis and kidney transplant patients with moderate-severe COVID-19 have a high mortality rate, around 30%, that is similar in the two populations, despite differences in their baseline characteristics. In these groups, the immunology of the disease has been poorly explored.

Methods

Thirty-two patients on dialysis or with kidney transplant and SARS-CoV-2 infection requiring hospitalization (COV group) were included in our study. Lymphocyte subsets, dendritic cell (DC) counts and monocyte activation were studied. SARS-CoV-2 anti-spike/anti-nucleocapsid were monitored, and baseline cytokines and chemokines were measured in 10 patients.

Results

The COV group, compared to healthy subjects and uninfected dialysis/kidney transplant controls, showed lower numbers of CD4 + and CD8 + T cells, Natural-Killer (NK), B cells, plasmacytoid and myeloid DCs, while the proportion of terminally differentiated B-cells was increased. IL6, IL10, IFN-α and chemokines involved in monocyte and neutrophil recruitment were higher in the COV group, compared to uninfected dialysis/kidney transplant controls.

Patients with severe disease had lower CD4 + , CD8 + and B-cell counts and lower monocyte HLA-DR expression. Of note, when comparing dialysis and kidney transplant patients with COVID-19, the latter group presented lower NK and pDC counts and monocyte HLA-DR expression. Up to 60 days after symptom onset, kidney transplant recipients showed lower levels of anti-spike antibodies compared to dialysis patients.

Conclusions

During SARS-CoV-2 infection, dialysis and kidney transplant patients manifest immunophenotype abnormalities; these are similar in the two groups, however kidney transplant recipients show more profound alterations of the innate immune system and lower anti-spike antibody response.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40620-021-01214-8.

Ten-year experience of an outpatient clinic for CKD-5 patients with multidisciplinary team and educational support

PURPOSE

To analyze the results of an outpatient clinic with a multidisciplinary team and educational support for patients with late-stage CKD (lsCKD), to check its possible effect on their outcomes.

METHODS

Longitudinal cohort study on patients followed up in the MaReA (Malattia Renale Avanzata = CKD5) outpatient clinic at ASST Spedali Civili of Brescia from 2005 to 2015 for at least six months. Trajectory of renal function over time has been evaluated only in those patients with at least four estimations of eGFR before referring to MaReA.

RESULTS

Seven hundred and six patients were enrolled, their mean age was 72 ± 14 years, 59% were males. At the end of the study, 147 (21%) were still on MaReA, 240 (34%) on dialysis, 92 (13%) on very low-protein diet (VLPDs), 13 (2%) on pre-hemodialysis clinic, 23 (3%) improved renal function, 10 (1%) transplanted, 62 (9%) transferred/lost to follow-up, and 119 (17%) died. Optimal dialysis start (defined as start with definitive dialysis access, as an out-patient and without lsCKD complications) occurred in 180/240 (75%) patients. The results showed a slower eGFR decrease during MaReA follow-up compared to previous renal follow-up: - 2.0 vs. - 4.0 mL/min/1.73 m² BSA/year (p < 0.05), corresponding to a median delay of 17.7 months in dialysis start in reference to our policy in starting dialysis. The patient cumulative survival was 75% after 24 months and 25% after 70.

LIMITATIONS

(1) lack of a control group, (2) one-center-study, (3) about all patients were Caucasians.

CONCLUSION

The follow-up of lsCKD patients on MaReA is associated with an optimal and delayed initiation of dialysis.

Supportive treatment for cast nephropathy in patients with multiple myeloma; a pilot study

Introduction: Cast nephropathy is a prevalent cause of acute kidney injury (AKI) in patients with myeloma. Objectives: The aim of this study is to define the outcome of a standardized supportive therapy for cast nephropathy. Patients and Methods: Retrospective analysis of the outcome of cast nephropathy in a University hospital for a period of five years. Data analysed; serum creatinine, estimated glomerular filtration rate (eGFR; mL/min/1.73 m2 BSA) and need for dialysis. Standardized therapy with the aim of preventing/removing tubular casts; fluid administration and mannitol to increase urine flow, sodium bicarbonate to alkalize the urine and low dose steroid to reduce peritubular inflammation. Statistical analysis: Student’s t-test or the Mann-Whitney test according to data distribution. A two-tailed P value <0.05 was considered statistically significant. Survival curve was drawn according to Kaplan and Meier. Results: Twenty-seven cases were reviewed. Upon admission, mean serum creatinine was 7.1±4.9 mg/dL and mean eGFR 6±4 mL/min/1.73 m2 BSA; 30% of patients had oligo-anuria. Diagnosis of cast nephropathy was presumptive in 23 patients, and renal biopsy proven in four. Hemodialysis was required by 10 (37%) patients, two of whom continued dialysis after discharge. At discharge, serum creatinine was 3.7±2.5 mg/dL and eGFR 20±13 mL/min/1.73 m2 BSA (P=0.002), and after a median of 3.4 months, the values were 2.9±2.1 mg/dL and 35±32 mL/min/1.73 m2 BSA, respectively. Patient survival was 60% after 24 months. Conclusion: Administration of fluid, mannitol, sodium bicarbonate and low-dose steroid may improve the outcome of cast nephropathy. Despite the fact that the study has many limitations, its findings could be the base for prospective controlled trials on cast nephropathy and could be useful in those countries where the expensive extracorporeal treatments are not available.

Liver Steatosis and Its Relation to Plasma Haemostatic Factors in Apparently Healthy Men - Role of the Metabolic Syndrome

The relationship between liver steatosis, evaluated by ultrasonography, and various plasma haemostatic factors was examined in 64 apparently healthy males, aged 38 years. Plasma levels of factor VII clotting activity (F-VIIc), plasminogen activator inhibitor-1 (PAI-1) activity and antigen, tissue-type plasminogen activator (t-PA) activity significantly differed in men with liver steatosis (n = 31) as compared with those without steatosis (n = 33). No significant differences were found in t-PA antigen and F-VII antigen. The men with liver steatosis also had significantly higher body mass index (BMI), plasma triglyceride and 2 h post-load insulin concentrations. While the differences in plasma haemostatic factors were substantially unchanged after adjustment for BMI, they totally disappeared when further allowance was made for plasma triglyceride and 2 h insulin concentrations. In conclusion, these results indicate that liver steatosis correlates specifically with increased PAI-1, F-VIIc and decreased t-PA levels, and suggest that such a relation is largely mediated by concomitant alterations in plasma triglyceride and insulin concentrations.

Expression of plasminogen activator inhibitor-1 in human adipose tissue: a role for TNF-alpha?

Elevated plasminogen activator inhibitor-1 (PAI-1) plasma levels, responsible for reduced fibrinolysis, are associated with animal and human obesity and with increased cardiovascular disease. The expression of PAI-1 has been found recently in animal and human adipose tissue. Factors and mechanisms regulating such an expression remain to be elucidated. In omental and/or subcutaneous biopsies from obese non-diabetic patients, incubated in Medium 199, we have confirmed that human adipose tissue expresses PAI-1 protein and mRNA; furthermore we have demonstrated that such an expression is clearly evident also in collagenase isolated human adipocytes and that it is stimulated by incubation itself and enhanced by exogenous human tumor necrosis factor-alpha (h-TNF-alpha). Since human adipose tissue produces TNF-alpha, to further characterize the relationship of PAI-1 to TNF-alpha, human fat biopsies were also incubated with Pentoxifylline (PTX) or Genistein, both known to inhibit endogenous TNF-alpha through different mechanisms. PTX caused a dose-dependent decrease of basal PAI-1 protein release, reaching 80% maximal inhibitory effect at 10(-3)M, the same inhibitory effect caused by Genistein at 100 microg/ml. This was associated to a marked inhibition of PAI-1 mRNA and of endogenous TNF-alpha production. Furthermore, when human fat biopsies were incubated in the presence of polyclonal rabbit neutralizing anti-human TNF-alpha antibody (at a concentration able to inhibit 100 UI/ml human TNF-alpha activity), a modest but significant decrease of the incubation induced expression of PAI-1 mRNA was observed (19.8+/-19.0% decrease, P = 0.04, n = 7). In conclusion, the results of this study demonstrate that PAI-I expression is present in human isolated adipocytes and that it is enhanced in human adipose tissue in vitro by exogenous TNF-alpha. Furthermore our data support the possibility of a main role of endogenous TNF-alpha on human adipose tissue PAI-1 expression. This cytokine, produced by human adipose tissue and causing insulin resistance, may be a link in the clinical relationship between insulin-resistance syndrome and increased PAI-1 plasma levels.

Ultrasonographic intra-abdominal depth and its relation to haemostatic factors in healthy males

OBJECTIVE

To examine the relationship of intra-abdominal fat to plasma haemostatic factors.

SUBJECTS

60 healthy, predominantly nonobese, male volunteers aged 38 years.

MEASUREMENTS

Anthropometry, sonographic intra-abdominal depth (IAD), as an indicator of intra-abdominal fat, plasma lipids, plasma insulin (at fasting and after glucose load), various plasma haemostatic factors.

RESULTS

Sonographic IAD correlated positively with plasma fibrinogen (r = 0.33; P < 0.01), PAI-1 activity (r = 0.52; P < 0.0001) and antigen (r = 0.32; P < 0.05), and negatively with t-PA activity, at baseline and after stasis (r = -0.28 and r = 0.31; P < 0.05). Factor VII levels did not correlate significantly with sonographic IAD. Haemostatic variables were also closely associated with BMI, plasma triglyceride and insulin concentrations. Most correlations of haemostatic factors with IAD disappeared after adjustment for either BMI or insulin or triglycerides, except PAI-1 levels which maintained a significant association even after simultaneous adjustment for all potential confounders.

CONCLUSIONS

These results, obtained by sonography, confirm our previous findings of significant associations of haemostatic variables with visceral fat accumulation by using computed tomography, and highlight the role of the intra-abdominal fat as an independent predictor of PAI-1 activity.

Liver steatosis and its relation to plasma haemostatic factors in apparently healthy men--role of the metabolic syndrome

The relationship between liver steatosis, evaluated by ultrasonography, and various plasma haemostatic factors was examined in 64 apparently healthy males, aged 38 years. Plasma levels of factor VII clotting activity (F-VIIc), plasminogen activator inhibitor-1 (PAI-1) activity and antigen, tissue-type plasminogen activator (t-PA) activity significantly differed in men with liver steatosis (n = 31) as compared with those without steatosis (n = 33). No significant differences were found in t-PA antigen and F-VII antigen. The men with liver steatosis also had significantly higher body mass index (BMI), plasma triglyceride and 2 h post-load insulin concentrations. While the differences in plasma haemostatic factors were substantially unchanged after adjustment for BMI, they totally disappeared when further allowance was made for plasma triglyceride and 2 h insulin concentrations. In conclusion, these results indicate that liver steatosis correlates specifically with increased PAI-1, F-VIIc and decreased t-PA levels, and suggest that such a relation is largely mediated by concomitant alterations in plasma triglyceride and insulin concentrations.

The white blood cell count: its relationship to plasma insulin and other cardiovascular risk factors in healthy male individuals

OBJECTIVES

To evaluate the relationships of total and differential white blood cell (WBC) count to the components of the so-called insulin resistance syndrome.

SUBJECTS AND DESIGN

The study population consisted of a random sample of 90 38-year-old healthy men with normal glucose tolerance.

INTERVENTIONS

A 75 g oral glucose tolerance test was performed in all participants.

MAIN OUTCOME MEASURES

Total and differential WBC count, lipids, blood pressure, plasma glucose, C-peptide and insulin (at fasting and 2 h after glucose load).

RESULTS

Total WBC count correlated consistently with plasma 2-h glucose (r = 0.38; P < 0.001), fasting and 2-h postload insulin (r = 0.26 and r = 0.33; P < 0.01-0.001, respectively) and C-peptide (r = 0.28 and r = 0.32; P < 0.01-0.001) concentrations. Smokers had significantly higher total leukocytes (P < 0.01), neutrophils and lymphocytes than nonsmokers. Furthermore, total WBC count correlated positively with body mass index, blood pressure, plasma triglycerides, fibrinogen, and negatively with HDL cholesterol concentration. As differential WBC count, most variables correlated essentially to neutrophils and/or lymphocytes, whereas plasma insulin and C-peptide concentrations correlated essentially to lymphocytes and monocytes, but not to neutrophils. In a multiple linear regression analysis, only 2-h plasma glucose (P < 0.01) and fibrinogen (P < 0.05) were positive predictors of total WBC count after adjusting for all potentially confounding variables.

CONCLUSIONS

The results indicate that increased, albeit normal, WBC count associates with the cluster of metabolic and haemodynamic disorders typical of the insulin resistance syndrome, and suggest that increased WBC count may be yet another component of this syndrome.

Moderate alcohol consumption and its relation to visceral fat and plasma androgens in healthy women

OBJECTIVE

To study the inter-relationships between daily alcohol intake, fat distribution and plasma androgens in order to verify whether daily alcohol intake correlates with abdominal body fat and, if so, to what extent such a relation is mediated by plasma androgens.

SUBJECTS

A random sample of 87 clinically healthy women (aged 38 y) with a light-moderate alcohol consumption and without clinical evidence suggestive of any endocrine disorder.

MEASUREMENTS

Anthropometric and computed tomography (CT scans made at the level of L4-L5 in a subgroup of 18 women) measurements of body fatness and adipose tissue distribution, main behavioural factors, including daily alcohol intake and plasma androgens (i.e. total and free testosterone levels).

RESULTS

After adjustment for BMI, cigarette smoking and physical activity, significant differences were found in waist circumference and waist-hip ratio as well as in plasma androgens with increasing daily alcohol intake. Waist-thigh ratio tended to parallel waist-hip ratio, but did not achieve statistical significance. In simple linear regression analysis, abdominal visceral fat area, derived from CT, correlated positively with both plasma free testosterone and alcohol intake. While the above reported difference in body fat distribution totally disappeared after controlling also for free testosterone level, the differences in plasma androgens with increasing alcohol intake remained essentially unchanged when allowance was made also for waist-hip ratio. In multiple linear regression analysis, daily alcohol intake appeared to be positively and independently correlated to both plasma total and free testosterone levels. Neither BMI nor waist-hip ratio nor fasting insulin made any significant contribution to the prediction of plasma androgens after daily alcohol intake had been taken into account.

CONCLUSIONS

The results of this study show that moderate alcohol consumption correlates with abdominal distribution of body fat, likely due to enlarged visceral fat area, and increased plasma androgenicity (i.e. higher total and free testosterone levels) in adult healthy women. These data also suggest that the relation between alcohol intake and fat distribution may be, at least in part, mediated by plasma androgens.

Visceral fat accumulation and its relation to plasma hemostatic factors in healthy men

The associations between abdominal visceral fat and the plasma hemostatic system were examined in 38-year-old healthy men (n=52) with a wide range of fatness and fat distribution. Plasma hemostatic factors and metabolic parameters, including glucose tolerance, were measured, and body fatness and adipose tissue distribution were assessed by using computed tomography. The men with more visceral fat (ie, higher than the median value [n=26]) had a less favorable metabolic profile than the men with less visceral fat (n=26). They also had significantly (P<.05) higher plasma fibrinogen, factor VIII clotting activity, tissue-type plasminogen activator antigen, and plasminogen activator inhibitor-1 (PAI-1) activity (19.2+/-2.4 versus 8.5+/-1.6 AU/mL, P<.001) and lower basal tissue-type plasminogen activator activity. After adjustment for plasma insulin, the men with larger abdominal visceral fat area still had significantly higher plasma PAI-1 activity, but no difference was found in any of the other hemostatic factors. In multiple linear regression analysis, abdominal visceral fat area was a positive predictor of plasma PAI-1 activity, but it failed to show any significant association with other hemostatic factors after controlling for plasma insulin. These results suggest the presence of relationships between abdominal visceral fat and several plasma hemostatic factors that are largely mediated by concomitant alterations in plasma insulin concentration. In addition, our results suggest that abdominal accumulation of visceral fat is an independent predictor of plasma PAI-1 activity.

Plasma factor VII and its relation to adipose tissue fatty acids and other atherogenic risk factors in healthy men

In this study the authors examined the relationships of plasma factor VII (F-VII) to adipose tissue fatty acid composition, as an objective index of the habitual dietary fat intake, as well as to a number of other atherogenic risk factors in 60 healthy male volunteers (aged 38 years). Significant positive correlations were found between plasma F-VII [measured as antigen (F-VIIAg) and coagulant activity, using bovine thromboplastin (F-VIIbt)] and body mass index (BMI), waist-thigh girth ratio (WTR), cigarette smoking and plasma triglyceride concentration. After adjustment for BMI, only plasma triglycerides remained positively correlated with F-VII (r = 0 center dot 27, P = 0 center dot 03, and r = 0 center dot 29, P < 0 center dot 01, for F-VIIbt and F-VIIAg respectively). A significant positive relation was found between F-VII and the total proportion of fatty acid as monounsaturated fatty acid (r = 0 center dot 26, P < 0 center dot 05, for F-VIIAg), whereas inverse relations were found between F-VII, the total proportion of fatty acid as polyunsaturated fatty acid (r = -0 center dot 26 and r = -0 center dot 25, P < 0 center dot 05, for F-VIIbt and F-VIIAg respectively), polyunsaturated-saturated fat ratio (r = -0 center dot 25, P < 0 center dot 05, for F-VIIbt) and, more significantly, between F-VII and adipose-tissue alpha-linolenic acid (r = -0 center dot 29, P < 0 center dot 01, for F-VIIbt and r = -0 center dot 49, P < 0 center dot 001, for F-VIIAg). All these correlations remained significant after matching for BMI. In a multiple linear regression analysis, only adipose tissue alpha-linolenic acid was a negative and independent predictor of F-VIIAg (P = 0 center dot 004) and, at borderline significance, of F-VIIbt (P = 0 center dot 061) when allowance was made for BMI, WTR, smoking and plasma triglycerides. In conclusion, this study shows significant relations between F-VII and adipose tissue fatty acid composition in healthy male individuals; it supports the possibility that adipose tissue poly-unsaturated fatty acids, derived from dietary intake, play a role in the relation between F-VII and coronary heart disease (CHD), thus suggesting that high dietary polyunsaturated fatty acid intake (especially alpha-linolenic acid) may reduce the risk for CHD by an improvement of a number of risk factors, including a lowering of plasma F-VII (both activity and antigen).

Cardiovascular risk profile in 38-year and 18-year-old men. Contribution of body fat content and regional fat distribution

OBJECTIVE

To evaluate whether young and middle-age men differ in blood pressure and serum lipid profiles and, if so, to what extent these differences are dependent on total body fat, regional fat distribution, plasma insulin and behavioural variables.

SUBJECTS

Random samples of 94 young (18 year-old) and 94 middle-age (38 year-old) healthy men matched for body mass index (BMI).

MEASUREMENTS

BMI, total body fat (by bioelectrical impedance), regional fat distribution (by anthropometry), serum lipids, blood pressure, fasting insulin and some behavioural variables.

RESULTS

Total body fat was similar in the two groups (mean +/- s.e.: 16.6 +/- 0.5 vs 16.0 +/- 0.6 kg and 20.8 +/- 0.5 vs 20 +/- 0.5%), while waist/hip circumference ratio (WHR) was significantly higher in middle-age as compared to young men (0.96 +/- 0.001 vs 0.92 +/- 0.003, P < 0.0001). The former also had significantly higher serum concentrations of total cholesterol (6.21 +/- 0.13 vs 4.10 +/- 0.10 mmol/l; P < 0.0001). LDL-cholesterol (4.24 +/- 0.11 vs 2.34 +/- 0.10 mmol/l; P < 0.0001), triglycerides 1.40 +/- 0.09 vs 1.02 +/- 0.06 mmol/l; P < 0.01) as well as higher systolic (134.0 +/- 1.6 vs 126.3 +/- 1.4 mmHg; P < 0.0001) and diastolic (86.8 +/- 0.9 vs 82.0 +/- 1.1 mmHg; P < 0.001) blood pressure values. HDL-cholesterol and fasting insulin concentrations were similar in the two groups (1.33 +/- 0.03 vs 1.28 +/- 0.03 mmol/l and 13.7 +/- 0.6 vs 14.7 +/- 0.7 mU/l, respectively). Significant differences in the two groups also were found in daily alcohol consumption (49.6 +/- 5.7 vs 20.0 +/- 3.4 g/day; P < 0.0001), whereas no significant differences were found in smoking and physical activity level. The comparison of subgroups (n = 41) of young and middle-age men matched for both BMI and WHR showed virtually unchanged differences in serum lipids and blood pressure. When age, BMI, WHR, fasting insulin and behavioural variables were included as independent variables in a multiple linear regression analysis in which subjects of the two groups were pooled, age was a significant predictor of total and LDL cholesterol, triglycerides and systolic blood pressure, insulin predicted HDL cholesterol and systolic blood pressure, BMI predicted triglycerides and diastolic blood pressure and WHR was not an independent predictor of any risk factor.

CONCLUSIONS

These results indicate that middle-age men have a cardiovascular risk profile less favourable than young men, which is largely independent of differences in total body fat content, regional fat distribution and behavioural variables.

Relationships of blood pressure to fibrinolysis: influence of anthropometry, metabolic profile and behavioural variables

OBJECTIVE

To investigate the relationship between blood pressure and the plasma fibrinolytic system and to verify whether this association was independent or mediated by one or more potential confounding factor.

DESIGN

A random sample of 94 males aged 38 years subdivided into normotensives, hypertensives and those hypertensives with the highest blood pressure values.

METHODS

Overall and regional obesity, blood lipids, fasting and 2-h post-load glucose, C-peptide and insulin levels, and main behavioural variables, including adipose tissue fatty acid composition (an objective index of dietary fat intake), were measured. The plasma fibrinolytic system was evaluated by determining activities and total plasma concentrations of both tissue-type plasminogen activator before and after venous occlusion, and its inhibitor plasminogen activator inhibitor type-1 (PAI-1).

RESULTS

PAI-1 activity was significantly higher in the hypertensives than in the normotensives. PAI-1 antigen tended to parallel PAI-1 activity, and levels of tissue-type plasminogen activator antigen and activity tended to be lower in the hypertensives at baseline and after venous occlusion, but not significantly different from those in the normotensives. The hypertensives also had significantly higher body mass index and body fat content (measured by bio-impedance), increased plasma triglycerides, uric acid, fasting and 2-h glucose, C-peptide and insulin concentrations. In univariate linear regression analysis both systolic and diastolic blood pressures were found to be positively correlated with PAI-1 levels (r = 0.27, P < 0.01, for both). This correlation was maintained after adjustment for total body fat, fasting glucose, fasting insulin concentration or adipose tissue alpha-linolenic acid; however, it was no longer significant after adjustment for plasma 2-h insulin, 2-h C-peptide, 2-h glucose or triglyceride levels. Multivariate regression analysis revealed that only 2-h insulin and triglyceride concentration showed an independent association with PAI-1 levels.

CONCLUSIONS

This study confirms that, in 38-year-old males, hypertension is associated with increased PAI-1 activity. It supports the possibility that the relationship between blood pressure and PAI-1 may reflect the overall effect of the insulin resistance syndrome (in particular hyperinsulinaemia and hypertriglyceridaemia) rather than a direct effect of blood pressure on the fibrinolytic system.

Hyperuricaemia: relationships to body fat distribution and other components of the insulin resistance syndrome in 38-year-old healthy men and women

The aim of this work was to evaluate whether hyperuricaemia correlates with the cluster of metabolic and haemodynamic disorders closely associated with insulin resistance syndrome (IRS) in young apparently healthy individuals also, and, if so, whether hyperinsulinaemia itself or some other component of this syndrome, are independently associated with hyperuricaemia. The subjects were a random population sample of 181 (M = 94/F = 87) 38-year-old apparently healthy subjects, non-diabetic, without a history of gout. Obesity (overall and regional), serum lipid profile, uric acid, fasting glucose and insulin, 2 h insulin after glucose-load (only in men), blood pressure and main behavioural variables were measured. As expected, most parameters were statistically different between men and women. In particular, serum uric acid levels were significantly higher in the male group than in female group (348 +/- 59 mumol l-1 vs 277 +/- 59 mumol l-1, P < 0.0001). After adjustment for sex, in pooled individuals, serum uric acid concentration showed positive associations with BMI (r = 0.21; P < 0.001), waist/hip girth (WHR; r = 0.45; P < 0.0001), waist/thigh girth (WTR; r = 0.35; P < 0.0001) and subscapula/triceps skinfold ratios (STR; r = 0.30; P < 0.001). Furthermore, serum uric acid was also positively correlated with fasting insulin (r = 0.23; P < 0.001), serum triglycerides (r = 0.34; P < 0.0001), LDL cholesterol (r = 0.16; P = < 0.01), diastolic blood pressure (r = 0.26; P < 0.001), and negatively with HDL/total cholesterol ratio (r = 0.28; P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

The anti-lipid A antibody HA-1A binds to rough gram-negative bacteria, fixes complement and facilitates binding to erythrocyte CR1 (CD35)

MoAbs to bacterial cell wall lipopolysaccharide are currently under evaluation for the treatment of Gram-negative sepsis. The mode of action of these reagents remains poorly understood. In this study we examined the ability of radiolabelled HA-1A (an IgM anti-lipid A MoAb) to bind in vitro to Salmonella minnesota (Re 595), Escherichia coli, and Streptococcus pyogenes. HA-1A was able to bind specifically to the 'rough' mutant Salm. minnesota, but not to a 'smooth' E. coli, or Strep. pyogenes. Binding to Salm. minnesota led to complement fixation which resulted in bacterial adherence to erythrocyte CR1, suggesting a possible mechanism whereby the antibody might enhance clearance of bacteria by facilitating delivery to the fixed mononuclear phagocytic system. We were not able to demonstrate the formation of immune complexes between free lipopolysaccharide and HA-1A in the presence of serum, nor the enhancement of complement-mediated binding of HA-1A:Salm. minnesota immune complexes to erythrocytes by antibiotic treatment. Binding of HA-1A to small bacterial fragments was, however, demonstrable after in vitro treatment with a beta-lactam antibiotic, which disrupts the bacterial cell wall, but not with gentamicin, an aminoglycoside antibiotic which blocks protein synthesis.