B-cell and T-cell receptor repertoire in chronic inflammatory demyelinating polyneuropathy, a prospective cohort study.

The immunopathophysiological mechanisms underlying chronic inflammatory demyelinating polyneuropathy (CIDP) in an individual patient are largely unknown. Better understanding of these mechanisms may aid development of biomarkers and targeted therapies. Both B- and T-cell dominant mechanisms have been implicated. We therefore investigated whether B-cell and T-cell receptor (BCR/TCR) repertoires might function as immunological biomarkers in CIDP. In this prospective cohort study, we longitudinally sampled peripheral blood of CIDP patients in three different phases of CIDP: starting induction treatment (IT), starting withdrawal from IVIg maintenance treatment (MT), and patients in remission (R). BCR and TCR repertoires were analyzed using RNA based high throughput sequencing. In baseline samples, the number of total clones, the number of dominant BCR and TCR clones and their impact on the repertoire was similar for patients in the IT, MT, and remission groups compared with healthy controls. Baseline samples in the IT or MT did not predict treatment response or potential relapse at follow-up. Treatment responders in the IT group showed a potential IVIg-induced increase in the number of dominant BCR clones and their impact at follow-up (baseline1.0 [IQR 1.0-2.8] vs. 6 m 3.5 [0.3-6.8]; P < .05, Wilcoxon test). Although the BCR repertoire changed over time, the TCR repertoire remained robustly stable. We conclude that TCR and BCR repertoire distributions do not predict disease activity, treatment response or response to treatment withdrawal.

Quantitative and qualitative aspects of standing-up behavior and the prevalence of osteochondrosis in Warmblood foals on different farms: could there be a link?

BACKGROUND: Osteochondrosis (OC) is a common, clinically important joint disorder in which endochondral ossification is focally disturbed. Reduced blood supply to growing cartilage is considered an important cause of the condition, which has both genetic and environmental origins. Housing conditions can influence cartilage injury through peak-pressure changes during limb sliding. Additionally, circulatory perturbation can cause the avascular necrosis of cartilage. In this study, we evaluated the type and frequency of limb sliding during standing up and the occurrence of OC in foals aged up to 12 months on different farms. METHODS: Standing-up behavior was observed in 50 weaned, group-housed, Dutch Warmblood foals aged 6-9 months at five farms using black-and-white surveillance cameras, and their standing-up behavior was scored using a predetermined ethogram. OC was scored using a categorical scale between 6 and 12 months of age in 50 foals in the weanling period, and in 48 from the weanling to yearling periods because two foals died in this time. RESULTS: At both 6 and 12 months of age, the total prevalence of OC differed between the farms: the lowest prevalence was observed on a farm with no sliding, and the highest prevalence was evident on a farm with a higher sliding frequency. The mean ratio of sliding versus normal standing-up behavior was 29% (range: 0-50%); i.e., foals experienced limb sliding during around 29% of standing-up maneuvres. The frequency of sliding instead of normal standing-up behavior differed significantly between the farms (range: 0-50%; P < 0.05), but significantly decreased when foals could better prepare themselves to stand, e.g., when there was an obvious provocation such as the announced approach of another foal (P < 0.05). CONCLUSIONS: Small but significant differences exist between farms in the sliding frequency and total OC incidence in Warmblood foals, but whether environmental factors are causally related to these differences requires further elucidation.

Rheumatoid arthritis synovial tissue harbours dominant B-cell and plasma-cell clones associated with autoreactivity.

OBJECTIVE: To identify potential autoreactive B-cell and plasma-cell clones by quantitatively analysing the complete human B-cell receptor (BCR) repertoire in synovium and peripheral blood in early and established rheumatoid arthritis (RA). METHODS: The BCR repertoire was screened in synovium and blood of six patients with early RA (ERA) (<6 months) and six with established RA (ESRA) (>20 months). In two patients, the repertoires in different joints were compared. Repertoires were analysed by next-generation sequencing from mRNA, generating >10 000 BCR heavy-chain sequence reads per sample. For each clone, the degree of expansion was calculated as the percentage of the total number of reads encoding the specific clonal sequence. Clones with a frequency ≥ 0.5% were considered dominant. RESULTS: Multiple dominant clones were found in inflamed synovium but hardly any in blood. Within an individual patient, the same dominant clones were detected in different joints. The majority of the synovial clones were class-switched; however, the fraction of clones that expressed IgM was higher in ESRA than ERA patients. Dominant synovial clones showed autoreactive features: in ERA in particular the clones were enriched for immunoglobulin heavy chain gene segment V4-34 (IGHV4-34) and showed longer CDR3 lengths. Dominant synovial clones that did not encode IGHV4-34 also had longer CDR3s than peripheral blood. CONCLUSIONS: In RA, the synovium forms a niche where expanded--potentially autoreactive--B cells and plasma cells reside. The inflamed target tissue, especially in the earliest phase of disease, seems to be the most promising compartment for studying autoreactive cells.

Deep sequencing of antiviral T-cell responses to HCMV and EBV in humans reveals a stable repertoire that is maintained for many years.

CD8(+) T-cell responses against latent viruses can cover considerable portions of the CD8(+) T-cell compartment for many decades, yet their initiation and maintenance remains poorly characterized in humans. A key question is whether the clonal repertoire that is raised during the initial antiviral response can be maintained over these long periods. To investigate this we combined next-generation sequencing of the T-cell receptor repertoire with tetramer-sorting to identify, quantify and longitudinally follow virus-specific clones within the CD8(+) T-cell compartment. Using this approach we studied primary infections of human cytomegalovirus (hCMV) and Epstein Barr virus (EBV) in renal transplant recipients. For both viruses we found that nearly all virus-specific CD8(+) T-cell clones that appeared during the early phase of infection were maintained at high frequencies during the 5-year follow-up and hardly any new anti-viral clones appeared. Both in transplant recipients and in healthy carriers the clones specific for these latent viruses were highly dominant within the CD8(+) T-cell receptor Vß repertoire. These findings suggest that the initial antiviral response in humans is maintained in a stable fashion without signs of contraction or changes of the clonal repertoire.

Inflamed target tissue provides a specific niche for highly expanded T-cell clones in early human autoimmune disease.

OBJECTIVE: To profile quantitatively the T-cell repertoire in multiple joints and peripheral blood of patients with recent onset (early) or established rheumatoid arthritis (RA) using a novel next-generation sequencing protocol to identify potential autoreactive clones. METHODS: Synovium of patients with recent onset (early) RA (<6 months) (n=6) or established RA (>18 months) (n=6) was screened for T-cell clones by sequencing over 10 000 T-cell receptors (TCR) per sample. T cells from paired blood samples were analysed for comparison. From two patients synovial T cells were obtained from multiple inflamed joints. The degree of expansion of each individual clone was based on its unique CDR3 sequence frequency within a sample. Clones with a frequency of over 0.5% were considered to be highly expanded clones (HEC). RESULTS: In early RA synovium, the T-cell repertoire was dominated by 35 HEC (median, range 2-70) accounting for 56% of the TCR sequenced. The clonal dominance in the synovium was patient specific and significantly greater than in established RA (median of 11 HEC (range 5-24) in established RA synovium accounting for 9.8% of T cells; p<0.01). 34% (range 28-40%) of the most expanded T-cell clones were shared between different joints in the same patients, compared with only 4% (range 0-8%) between synovium and blood (p=0.01). CONCLUSIONS: In RA, a systemic autoimmune disease, the inflamed synovium forms a niche for specific expanded T-cell clones, especially in early disease. This suggests that, at least in RA, autoreactive T cells should be addressed specifically in the inflamed tissue, preferably in the early phase of the disease.

Genome sequence of Neisseria meningitidis serogroup B strain H44/76.

Neisseria meningitidis is an obligate human pathogen. While it is a frequent commensal of the upper respiratory tract, in some individuals the bacterium spreads to the bloodstream, causing meningitis and/or sepsis, which are serious conditions with high morbidity and mortality. Here we report the availability of the genome sequence of the widely used serogroup B laboratory strain H44/76.

The MEIS1 oncogene is highly expressed in neuroblastoma and amplified in cell line IMR32.

Neuroblastoma is an embryonal tumor originating from neural crest-derived cells. Here we present the serendipitous cloning of amplified sequences of chromosome 2p15 in neuroblastoma cell line IMR32. The amplified region was analyzed for oncogene activation using a SAGE (serial analysis of gene expression) library of IMR32. SAGE permits a quantitative analysis of all transcripts of a tissue or cell line. The expression of genes and ESTs mapping within a 30-cR region covering the amplicon was compared to 4 additional SAGE libraries of neuroblastomas and 12 SAGE libraries of other tissues in the CGAP databases. The IMR32 SAGE database revealed increased expression of the MEIS1 oncogene, whereas other SAGE libraries showed little or no MEIS1 expression. MEIS1 turned out to be highly amplified and overexpressed in IMR32. Analysis of 24 neuroblastoma cell lines and 22 tumors showed high-level expression in about 25% of the cases. The MEIS1 homeobox protein forms a complex with the HOXA9 and PBX proteins that are implicated in human leukemia. MEIS1 is a target of retroviral insertion in murine leukemia. This is the first report of a MEIS1 amplification and high expression levels in human cancer and the first time that identification of a candidate target of amplification is facilitated by high-throughput mRNA expression profiling.

USAGE: a web-based approach towards the analysis of SAGE data. Serial Analysis of Gene Expression.

MOTIVATION: SAGE enables the determination of genome-wide mRNA expression profiles. A comprehensive analysis of SAGE data requires software, which integrates (statistical) data analysis methods with a database system. Furthermore, to facilitate data sharing between users, the application should reside on a central server and be accessed via the internet. Since such an application was not available we developed the USAGE package. RESULTS: USAGE is a web-based application that comprises an integrated set of tools, which offers many functions for analysing and comparing SAGE data. Additionally, USAGE includes a statistical method for the planning of new SAGE experiments. USAGE is available in a multi-user environment giving users the option of sharing data. USAGE is interfaced to a relational database to store data and analysis results. The USAGE query editor allows the composition of queries for searching this database. Several database functions have been included which enable the selection and combination of data. USAGE provides the biologist increased functionality and flexibility for analysing SAGE data. AVAILABILITY: USAGE is freely accessible for academic institutions at http://www.cmbi.kun.nl/usage/. The source code of USAGE is freely available for academic institutions on request from the first author.

The diuretic effect of calcium entry blockade in normals and hypertensive patients.

Calcium entry blockers have been shown to exert hemodynamic and diuretic effects in the kidney. The diuretic effects can be demonstrated most clearly in the isolated perfused kidney, not influenced by compensatory mechanisms such as a lower blood pressure or changes of hormones. However, they can also be shown in vivo in humans. We studied the renal effects of calcium entry blockade after the first dosage and after continued oral dosages of 20 mg nicardipine tid in patients with essential hypertension and in normotensive controls. Renal function was determined during maximal free water clearance, allowing estimation of changes in "proximal" and "distal" tubular sodium reabsorption. Results showed a natriuretic effect. In the control subjects, clearance results were compatible with a decrease of proximal and distal tubular reabsorption, but in the hypertensive group natriuresis was mainly achieved by an increase of the glomerular filtration rate and a decrease of fractional distal reabsorption. In both groups the natriuresis occurred concomitantly with a lower blood pressure. The ratio plasma renin activity/plasma aldosterone concentration increased, although nicardipine did not inhibit the increase of plasma aldosterone during angiotensin II infusion. Pre-treatment with the calcium entry blocker nitrendipine enhanced the natriuretic effect of atrial natriuretic factor (ANF) in sodium replete normal volunteers. Facilitation of sodium excretion by human ANF may be an additional diuretic mechanism of calcium entry blockers.

Pharmacokinetics of lisinopril in hypertensive patients with normal and impaired renal function.

The pharmacokinetics of lisinopril was studied after administration of single and multiple doses of 5 mg to hypertensive patients with normal and impaired renal function. In patients with severe renal failure the peak concentrations were higher, the decline in serum concentration was slower and the time to peak concentration was extended. Accumulation of lisinopril was highly correlated with the creatinine clearance. The effective half-life was doubled and tripled in patients with mild and severe renal impairment, respectively, as compared to patients with a normal renal function. Lisinopril lowered blood pressure in all three groups over 24 h. It is suggested that smaller doses of lisinopril should be administered to patients with severe renal failure.

Lisinopril in hypertensive patients with and without renal failure.

Lisinopril (MK521), a lysine analogue of enalaprilic acid, the bioactive metabolite of enalapril, has a longer half-life than enalaprilic acid, and is excreted unchanged in the urine. Its kinetic profile and antihypertensive and hormonal effects have been investigated in an open study in 3 groups each of 6 hypertensive patients, with normal, moderate and severe impairment of renal function. Serum drug level, blood pressure, converting enzyme activity (CEA), plasma renin activity (PRA), aldosterone concentration (PAC), and serum potassium and creatinine were measured during 1 week following a single oral dose and subsequently following 8 daily doses of 5 mg lisinopril. Accumulation of lisinopril was found in the severe renal failure group. CEA was suppressed to less than 10% of its initial value from 4 to 24 h after the initial dose in all three groups, and the suppression was more marked and lasted longer in patients with severe renal failure. An inverse correlation was found in all patients between log serum lisinopril concentration and log CEA. Lisinopril lowered blood pressure in all three groups over 24 h. PRA rose and PAC fell similarly in the groups. Serum potassium increased in the renal failure groups and creatinine remained unchanged in all groups. Thus, when lisinopril 5 mg is given daily to patients with severe renal failure it may accumulate. The high serum lisinopril concentration does not cause an excessive antihypertensive effect. In patients with severe renal failure, adjustment of the dose or the dosing frequency to the degree of renal failure is recommended to avoid administration of doses in excess of those required to achieve adequate inhibition of converting enzyme.

The effect of converting enzyme inhibition on the enhanced proximal sodium reabsorption induced by chronic diuretic treatment in patients with essential hypertension.

During chronic chlorthalidone treatment of patients with essential hypertension, distal tubular sodium reabsorption is continuously inhibited. At the same time, sodium balance is maintained by an increase of the proximal tubular sodium reabsorption. In the present study, we investigated whether this increase is caused by a stimulated renin-angiotensin system (RAS). For this purpose, the renal effects of converting enzyme inhibition (CEI) were evaluated in 12 patients with essential hypertension who remained hypertensive despite chronic chlorthalidone treatment. After 6 weeks of chlorthalidone, an intravenous injection of 10 mg enalaprilic acid decreased the mean arterial pressure (MAP) from 110 to 102 mm Hg. The effective renal plasma flow (ERPF) increased. However, glomerular filtration rate (GFR) and the fractional excretions of sodium, lithium and free water did not change significantly. After 2 additional weeks of chlorthalidone combined with enalapril 20 mg b.i.d., MAP fell to 90 mm Hg, ERPF remained elevated and plasma aldosterone concentration decreased. As in the acute study, no significant changes were detected in the GFR and the fractional excretions of sodium, lithium or free water. Extracellular fluid volume was not diminished during these 2 weeks. Fractional proximal sodium reabsorption during chronic chlorthalidone therapy was higher when calculated from free water clearance (91%) than from the lithium clearance (71%), but neither of the two were affected by acute or chronic CEI. The results of this study suggest that during chronic diuretic treatment, maintenance of sodium balance by increased proximal reabsorption is not dependent on the stimulated RAS, or alternatively, that this function of the RAS is exactly counterbalanced by another effect of CEI, possibly by the fall in blood pressure.

Comparison of enalapril and propranolol in essential hypertension.

In 40 patients with essential hypertension, enalapril was compared with propranolol as an antihypertensive agent in a double-blind study. The patients were randomly given either enalapril 5-10-20 mg bid or propranolol 40-80-120 mg bid in a treatment consisting of step-by-step increases in dosage. When the diastolic blood pressure remained greater than 90 mm Hg on the highest dosage, hydrochlorothiazide was added. Both enalapril and propranolol reduced blood pressure, although the patients tended to achieve lower blood pressures while on enalapril. More patients on propranolol required additional diuretic therapy than patients on enalapril. Propranolol reduced heart rate; with enalapril there were no changes in heart rate. Both drugs increased serum potassium and urea. Plasma renin substrate was reduced by enalapril, but raised by propranolol. Enalapril increased plasma renin activity and angiotensin I, while propranolol reduced both. Converting enzyme activity was lowered with enalapril but was unchanged with propranolol. Both drugs reduced angiotensin II. Plasma aldosterone concentration was more suppressed with propranolol than with enalapril.

Changes in blood pressure and body fluid volumes during diuretic therapy in patients with essential hypertension who receive enalapril.

We evaluated the effect of additional chlorthalidone therapy on blood pressure and body fluid volumes in 10 patients with essential hypertension who did not respond to chronic converting enzyme inhibition with enalapril. Values assessed after 3 days and 6 weeks of combined enalapril and chlorthalidone therapy were compared with initial values during enalapril monotherapy. After 3 days the mean arterial pressure (MAP), plasma volume (PV), blood volume (BV), and extracellular fluid volume (ECFV) decreased. There was a positive correlation between the percentage decreases in MAP and BV. After 6 weeks the MAP decreased further, but the decreases in PV, BV, and ECFV were less pronounced. At this time there was a positive correlation between the percentage decreases in MAP and ECFV. Our results support the hypothesis that contraction of the ECFV is an antihypertensive mechanism of diuretics. The antihypertensive effect of diuretics is enhanced during converting enzyme inhibition, while the body remains protected against volume deficits, possibly by the lower blood pressure itself.

Changes in haemodynamics and body fluid volume due to enalapril in patients with essential hypertension on chronic diuretic therapy.

In 12 patients with essential hypertension who remained hypertensive despite chronic chlorthalidone treatment, the effect of 2 weeks of additional therapy with the converting enzyme inhibitor (CEI) enalapril on blood pressure and body fluid volumes has been evaluated. The objective was to examine the influence of a diuretic-stimulated renin-angiotensin-aldosterone system (RAAS) on haemodynamics and body fluid volume. Mean arterial pressure (MAP -21%), total peripheral resistance index (TPRI -22%) and plasma aldosterone concentration (PAC -39%) were decreased, and plasma renin activity (PRA 660%) was increased. The average heart rate (HR), cardiac index (CI), plasma volume (PV), blood volume (BV), extracellular fluid volume (ECFV) and body weight (BW) remained unchanged. A negative correlation was found between the per cent changes in ECFV and PAC. Thus, body fluid volumes during chronic diuretic treatment are well preserved even when the RAAS with its sodium retaining properties is suppressed by CEI. Possible mechanisms are a volume (not angiotensin II) - dependent stimulation of aldosterone and a fall in blood pressure.

Influence of nicardipine on blood pressure, renal function and plasma aldosterone in normotensive volunteers.

The influence of the calcium antagonist nicardipine on intrarenal sodium handling and angiotensin II induced secretion of aldosterone was investigated in 18 normotensive volunteers after the first dose and after 1 week of treatment (20 mg three times daily). A short-lasting natriuresis was observed, which was caused by a decreased reabsorption of sodium localised in both proximal and distal tubules. Log plasma renin activity (PRA) fell significantly on each day during angiotensin II infusion, while log-plasma aldosterone (PA) rose significantly. The log PRA/log PA ratio was increased during nicardipine treatment. The secretion of aldosterone, induced by angiotensin II, was not influenced by nicardipine treatment. No effect of the drug on adrenal responsiveness to angiotensin II was found.

Antihypertensive and renal effects of nicardipine.

Both the acute blood pressure lowering and renal effects of the calcium antagonist nicardipine and those after 1 week's treatment were investigated in 10 normotensive volunteers and in 10 patients with mild to moderate essential hypertension. After 1 week of placebo, nicardipine was administered orally for 1 week (20 mg three times daily), Investigations, done on the first and last day of nicardipine treatment were compared with those on the last day of placebo. During water loading, nicardipine increased urinary volume and urinary excretion of sodium significantly after 1 week nicardipine treatment. In the normotensive group the natriuretic effect was caused by a decrease of fractional proximal and distal reabsorption of sodium. In the hypertensive group the natriuresis was achieved mainly by an increase of the rate of glomerular filtration (GFR) and also by a slight distal effect. Our results show that nicardipine had natriuretic effects. There were trends suggesting that the renal effects may differ between patients with essential hypertension and normotensive volunteers, but the findings might also be related to differences in age between the groups.