Jaap A. Bakker

Predicting cardiopulmonary involvement in patients with systemic sclerosis: complementary value of nailfold videocapillaroscopy patterns and disease-specific autoantibodies.

ObjectivenTo evaluate the prevalence of anti-extractable nuclear antigen (anti-ENA) antibodies in Dutch SSc patients and the predictive power of the combination of specific anti-ENA antibodies and nailfold videocapillaroscopy (NVC) patterns to improve identification of patients with high risk for cardiopulmonary involvement.nnnMethodsnA total of 287 patients (79%) from the Leiden SSc-Cohort had data available on NVC-pattern (no SSc-specific, early, active, late) and anti-ENA antibodies. Associations between anti-ENA/NVC combinations with cardiopulmonary parameters were explored using logistic regression.nnnResultsnPrevalence of ACA was 37%, anti-Scl-70 24%, anti-RNP 9%, anti-RNAPIII 5%, anti-fibrillarin 4%, anti-Pm/Scl 3%, anti-Th/To 0.3% and anti-Ku 1.4%. NVC showed a SSc-specific pattern in 88%: 10% early, 42% active and 36% late. The prevalence of different NVC patterns was equally distributed among specific anti-ENA antibodies, except for the absence of early pattern in anti-RNP positive patients. Fifty-one percent had interstitial lung disease (ILD), 59% had decreased diffusion capacity for carbon monoxide and 16% systolic pulmonary artery pressure >35 mmHg (sPAP↑). Regardless of ENA-subtype, NVC-pattern showed a stable association with presence of ILD or sPAP↑. For ILD, the odds ratios (ORs) were 1.3-1.4 ( P < 0.05 for analyses with anti-RNAPIII, anti-RNP). For diffusion capacity for carbon monoxide, the OR was 1.5 ( P < 0.05 for analyses with ACA, anti-Scl-70, anti-RNAPIII, anti-RNP). For sPAP↑, the ORs were 2.2-2.4 ( P < 0.05 for analyses with anti-RNAPIII, anti-RNP).nnnConclusionnIn Dutch SSc patients, all SSc-specific auto-antibodies were found, with ACA and anti-Scl-70 being the most prevalent. Strikingly, the association between NVC-pattern and heart/lung involvement was independent of specific anti-ENA antibodies, which might indicate microangiopathy is an important cause of organ involvement.

Defective postreperfusion metabolic recovery directly associates with incident delayed graft function

Delayed graft function (DGF) following kidney transplantation affects long-term graft function and survival and is considered a manifestation of ischemia reperfusion injury. Preclinical studies characterize metabolic defects resulting from mitochondrial damage as primary driver of ischemia reperfusion injury. In a comprehensive approach that included sequential establishment of postreperfusion arteriovenous concentration differences over the human graft, metabolomic and genomic analysis in tissue biopsies taken before and after reperfusion, we tested whether the preclinical observations translate to the context of clinical DGF. This report is based on sequential studies of 66 eligible patients of which 22 experienced DGF. Grafts with no DGF immediately recovered aerobic respiration as indicated by prompt cessation of lactate release following reperfusion. In contrast, grafts with DGF failed to recover aerobic respiration and showed persistent adenosine triphosphate catabolism indicated by a significant persistently low post reperfusion tissue glucose-lactate ratio and continued significant post-reperfusion lactate and hypoxanthine release (net arteriovenous difference for lactate and hypoxanthine at 30 minutes). The metabolic data for the group with DGF point to a persistent post reperfusion mitochondrial defect, confirmed by functional (respirometry) and morphological analyses. Thexa0archetypical mitochondrial stabilizing peptide SS-31 significantly preserved mitochondrial function in human kidney biopsies following simulated ischemia reperfusion. Thus, development of DGF is preceded by a profound post-reperfusion metabolic deficit resulting from severe mitochondrial damage. Strategies aimed at preventing DGF should be focused on safeguarding a minimally required post-reperfusion metabolic competence.

C1q Deficiency and Neuropsychiatric Systemic Lupus Erythematosus

C1q deficiency is a rare immunodeficiency, which is strongly associated with the development of systemic lupus erythematosus (SLE). A mutation in one of the C1q genes can either lead to complete deficiency or to low C1q levels with C1q polypeptide in the form of low-molecular weight (LMW) C1q. Patients with C1q deficiency mainly present with cutaneous and renal involvement. Although less frequent, neuropsychiatric (NP) involvement has also been reported in 20% of the C1q-deficient patients. This involvement appears to be absent in other deficiencies of early components of the complement classical pathway (CP) (C1r/C1s, C2, or C4 deficiencies). We describe a new case with C1q deficiency with a homozygous G34R mutation in C1qC-producing LMW-C1q presenting with a severe SLE flare with NP involvement. The serum of this patient contained very low levels of a LMW variant of C1q polypeptides. Cell lysates contained the three chains of C1q, but no intact C1q was detected, consistent with the hypothesis of the existence of a LMW-C1q. Furthermore, we provide a literature overview of NP-SLE in C1q deficiency and hypothesize about the potential role of C1q in the pathogenesis of NP involvement in these patients. The onset of NP-SLE in C1q-deficient individuals is more severe when compared with complement competent NP-SLE patients. An important number of cases present with seizures and the most frequent findings in neuroimaging are changes in basal ganglia and cerebral vasculitis. A defective CP, because of non-functional C1q, does not protect against NP involvement in SLE. The absence of C1q and, subsequently, some of its biological functions may be associated with more severe NP-SLE.

Anti-citrullinated protein antibodies in the diagnosis of rheumatoid arthritis (RA) : diagnostic performance of automated anti-CCP-2 and anti-CCP-3 antibodies assays

This study compares the diagnostic performance of a second generation anti-cyclic citrullinated peptide antibody (CCP2) with a third generation anti-CCP antibodies assay (CCP3), as well as the combination of both tests. Serum samples of 127 patients were analyzed. IgG anti-CCP 2 and IgM rheumatoid factor were determined by EliA™ technique on a Phadia 250 instrument (Thermo Fisher Scientific), anti-CCP3 by the Quanta Flash™ anti-CCP3 IgG kit, BIO-FLASH Rapid Response Chemiluminscence Analyzer (INOVA Diagnostics). Diagnostic performance was compared using ROC-curves, sensitivity, specificity, likelihood ratios, and predictive values. Logistic regressions were used to investigate whether using both tests (anti-CCP2 and anti-CCP3) gives a better prediction of rheumatoid arthritis. At the manufacturer’s cut-offs sensitivity and specificity were 79.4 and 61.0% for CCP3 and 80.9 and 69.5% for CCP2. No significant differences could be observed regarding the areas under the curve (AUC) of both ROC-curves. The optimal cut-off point for CCP2 was 10.5xa0U/ml (sensitivity of 75.0% and specificity of 80.0%) and 5.6xa0U/ml for CCP3 (sensitivity of 86.9% and specificity of 61.0%). Binary logistic regressions indicated that the likelihood of having rheumatoid arthritis (RA) is significantly higher when testing positive on both CCP2 and CCP3 compared to CCP2 or CCP3 alone. In our cohort, comparable performance was found between the two CCP assays. Positivity for both CCP2 and CCP3 resulted in the most specific identification of RA patients. In patients with joint complaints suspected of having RA and with a weakly positive CCP 2 (≥7 and ≤16xa0U/ml) CCP3 testing could be of additive value for diagnosing RA.

Proof of concept that most borderline Quantiferon results are true antigen-specific responses

Interferon-γ release assays (IGRAs) such as Quantiferon (QFT) that detect T-cell responses to antigens specific for Mycobacterium tuberculosis (MTB) have superior specificity to the tuberculin skin test (TST). While IGRAs are technically robust and the test result is a simple positive or negative, the interpretation nevertheless requires thorough understanding of the tests characteristics [1]. An area of debate is that of “borderline” results near the cut-off value, mentioned first in the setting of serial screening of health care workers [2]. While different authors used different ranges of test results under this denominator, borderline results were generally attributed to random assay variability [3, 4]. In reproducibility studies, conversions and reversions were often seen around the manufacturer-recommended cut-off, with the advice to “interpret such results cautiously” [5, 6]. Most borderline Quantiferon results are antigen-specific responses, defying the common assumption of random variation http://ow.ly/9a0X30fQBCO

Excessive neutrophil extracellular trap formation in ANCA-associated vasculitis is independent of ANCA

Neutrophil extracellular traps (NETs) are auto-antigenic strands of extracellular DNA covered with myeloperoxidase (MPO) and proteinase3 (PR3) that can be a source for the formation of anti-neutrophil cytoplasmic autoantibodies (ANCAs). The presence of NETs was recently demonstrated in renal tissue of patients with ANCA-associated vasculitis (AAV). NET formation was enhanced in AAV, suggesting that MPO-ANCA could trigger NET formation, supporting axa0vicious circle placing NETs in the center of AAV pathogenesis. Here we investigated NET formation in 99xa0patients with AAV by a novel highly sensitive and automated assay. There was a significant excess of exxa0vivo NET formation in both MPO-ANCA- and PR3-ANCA-positive patients with AAV compared to healthy individuals. Excessive NET formation did not correlate with serum ANCA levels. Likewise, immunoglobulin G depletion had no effect on excessive NET formation in patients with AAV, indicating an ANCA-independent process. Next, we explored the relation of excessive NET formation to clinical disease in ten patients with AAV and showed that excessive NET formation was predominantly found during active disease, more so than during remission. Excessive NET formation was found in patients with AAV hospitalized forxa0disease relapse but not during severe infection. Thus, excessive NET formation in AAV is independent of ANCA, and an excess of exxa0vivo NET formation was related to active clinical disease in patients with AAV and a marker ofxa0autoimmunity rather than infection.

Recurrent respiratory tract infections (RRTI) in the elderly: A late onset mild immunodeficiency?

Elderly with late-onset recurrent respiratory tract infections (RRTI) often have specific anti-polysaccharide antibody deficiency (SPAD). We hypothesized that late-onset RRTI is caused by mild immunodeficiencies, such as SPAD, that remain hidden through adult life. We analyzed seventeen elderly RRTI patients and matched controls. We determined lymphocyte subsets, expression of BAFF receptors, serum immunoglobulins, complement pathways, Pneumovax-23 vaccination response and genetic variations in BAFFR and MBL2. Twelve patients (71%) and ten controls (59%) had SPAD. IgA was lower in patients than in controls, but other parameters did not differ. However, a high percentage of both patients (53%) and controls (65%) were MBL deficient, much more than in the general population. Often, MBL2 secretor genotypes did not match functional deficiency, suggesting that functional MBL deficiency can be an acquired condition. In conclusion, we found SPAD and MBL deficiency in many elderly, and conjecture that at least the latter arises with age.

The hypoxanthine-xanthine oxidase axis is not involved in the initial phase of clinical transplantation-related ischemia-reperfusion injury

The hypoxanthine-xanthine oxidase (XO) axis is considered to be a key driver of transplantation-related ischemia-reperfusion (I/R) injury. Whereas interference with this axis effectively quenches I/R injury in preclinical models, there is limited efficacy of XO inhibitors in clinical trials. In this context, we considered clinical evaluation of a role for the hypoxanthine-XO axis in human I/R to be relevant. Patients undergoing renal allograft transplantation were included (n = 40) and classified based on duration of ischemia (short, intermediate, and prolonged). Purine metabolites excreted by the reperfused kidney (arteriovenous differences) were analyzed by the ultra performance liquid chromatography-tandem mass spectrometer (UPLCMS/MS) method and tissue XO activity was assessed by in situ enzymography. We confirmed progressive hypoxanthine accumulation (P < 0.006) during ischemia, using kidney transplantation as a clinical model of I/R. Yet, arteriovenous concentration differences of uric acid and in situ enzymography of XO did not indicate significant XO activity in ischemic and reperfused kidney grafts. Furthermore, we tested a putative association between hypoxanthine accumulation and renal oxidative stress by assessing renal malondialdehyde and isoprostane levels and allantoin formation during the reperfusion period. Absent release of these markers is not consistent with an association between ischemic hypoxanthine accumulation and postreperfusion oxidative stress. On basis of these data for the human kidney we hypothesize that the role for the hypoxanthine-XO axis in clinical I/R injury is less than commonly thought, and as such the data provide an explanation for the apparent limited clinical efficacy of XO inhibitors.

Metabolic events in HIV-infected patients using abacavir are associated with erythrocyte inosine triphosphatase activity

ObjectivesnAbacavir use has been associated with an increased risk of cardiovascular disease (CVD) and metabolic events in HIV-infected patients, although this finding was not consistently found. It is unclear whether abacavir only increases this risk in subpopulations of HIV-infected patients. It may be hypothesized that inosine 5-triphosphate pyrophosphohydrolase (ITPase), an enzyme involved in the metabolism of purine analogues used in HIV treatment, plays a role in the risk of CVD and metabolic events in HIV-infected patients.nnnMethodsnITPase activity and ITPA genotype were determined in 393 HIV-infected patients. ITPase activity <4u2009mmol IMP/mmol Hb/h was considered decreased. ITPA polymorphisms tested were: c.94C>A (rs1127354) and c.124u205f+u205f21A>C (rs7270101). ORs were determined using generalized estimating equation models for developing CVD in patients who had ever been exposed to abacavir, tenofovir or didanosine and for developing metabolic events in patients currently using these drugs.nnnResultsnIn patients using abacavir, metabolic events were associated with ITPase activity. No association was demonstrated for tenofovir or didanosine. The OR for metabolic events was 3.11 in patients using abacavir with normal ITPase activity (95% CI 1.34-7.21; Pu2009=u20090.008) compared with patients with decreased ITPase activity [adjusted for age, BMI, cumulative duration of combination ART (cART) use and the use of PI and NNRTI]. CVD was not associated with ITPase activity or ITPA genotype.nnnConclusionsnThis study shows, for the first time, that ITPase activity is associated with the occurrence of metabolic events in patients using abacavir. Further studies are needed to confirm this association and to elucidate the possible mechanism.

Peripheral Neuropathy, Episodic Rhabdomyolysis, and Hypoparathyroidism in a Patient with Mitochondrial Trifunctional Protein Deficiency

A combination of unexplained peripheral neuropathy, hypoparathyroidism, and the inability to cope with metabolic stress could point to a rare inborn error of metabolism, such as mitochondrial trifunctional protein (MTP) deficiency.Here, we describe a 20-year-old woman who was known since childhood with axonal motor sensory polyneuropathy of unknown origin. She presented with progressive dyspnoea, and increased muscle weakness, preceded by 6 days of fever, vomiting, and diarrhoea. Laboratory testing showed rhabdomyolysis, and hypocalcaemia with low parathyroid levels. The patient was intubated because of respiratory insufficiency and a viral and bacterial pneumonia was diagnosed. She was discharged after 16 days of admission. Metabolic screening, performed at the time of rhabdomyolysis, showed increased concentrations of long-chain 3-hydroxyacyl carnitine species, together with elevated urinary excretion of 3-hydroxy dicarboxylic acids. Decreased activity of long-chain 3-hydroxyacyl-CoA dehydrogenase and long-chain 3-ketoacyl-CoA thiolase in peripheral lymphocytes and fibroblasts confirmed a MTP deficiency. Sequence analysis of the HADHB gene showed two heterozygous variants: c.209+1G>C (splicing defect) and c.980T>C (p.Leu327Leu). When the acylcarnitine profile was repeated after the episode of rhabdomyolysis had resolved it showed no abnormalities.Our case illustrates a cluster of peripheral neuropathy, episodic rhabdomyolysis, and hypoparathyroidism in a patient with MTP deficiency caused by mutations in the HADHB gene. It stresses the importance of performing metabolic screening when patients are most symptomatic, as normal results can be found at times when no metabolic stress is present. Screening is relatively easy and timely diagnosis has important implications for treatment.