Identification of a novel low-affinity receptor for human interleukin-7.

Human recombinant interleukin-7 (IL-7) was labeled with biotin and used to examine IL-7 receptor (IL-7R) expression and regulation on human primary hematopoietic cells, the monocytoid line THP1, and a range of B- and pre-B-celi lines by flow cytometry. A strong intensity of staining was observed using relatively high (greater than 1 x 10(-7) mol/L) concentrations of biotinylated IL-7 on the majority of cell types examined. This reactivity, which could be effectively competed with excess unlabeled IL-7, did not correlate with either mRNA levels for the cloned receptor or with estimates of IL-7R expression determined by [125I]IL-7 binding. Staining of cells with a titration of biotinylated IL-7 showed, at concentrations greater than 1 x 10(-7) mol/L binding with a Ka in the range of 1 x 10(6) mol/L-1, to 1 x 10(7) mol/L-1, an affinity 100 to 1,000 times lower than that reported for the cloned IL-7 receptor. Further data suggesting the existence of a distinct low- affinity IL-7R were provided by two antibodies specific for the cloned IL-7R. Staining with these monoclonal antibodies (MoAbs) correlated with both IL-7R mRNA levels and receptor expression determined by [125I]IL-7 binding, but was not compatible with the distribution of reactivity seen with biotinylated IL-7. Using tritiated biotin to label IL-7, it was estimated that the total number of IL-7 binding sites on the cell lines examined ranged from 1 x 10(4) to at least 5 x 10(5)/cell. Cross-linking studies showed that [125I]IL-7 associated with two major proteins of approximately 62 Kd and 70 Kd on the surface of RPMI 1788 and THP1 cells, in contrast to the 75- to 80 Kd molecule characteristic of the previously cloned receptor, expressed on the surface of Daudi cells. Proliferation of THP1 cells, expressing only the low-affinity form of IL-7R and lacking detectable IL-7R mRNA, could be inhibited by the addition of IL-7 in a concentration-dependent fashion, indicating that, at least on this cell line, binding of IL-7 with a Ka of 1 x 10(6) mol/L-1 to 1 x 10(7) mol/L-1 can transduce a biological signal. Taken together, the data contained in this report demonstrate the existence of a low-affinity IL-7R, expressed in high numbers on hematopoietic cells of different lineages, which is the product of a gene distinct from that encoding the cloned IL-7R.     

Importance of serum interleukin-6 as a mediator of systemic inflammation in patients with alpha-1 antitrypsin deficiency

The objective of this study was to determine whether high concentrations of circulating interleukin-6 (IL-6) and/or the soluble receptor of IL-6 (SRIL-6) may mediate systemic inflammatory activity in patients with alpha-1 antitrypsin deficiency (AATD). To that end we assessed serum concentrations of IL-6 and SRIL-6 for 7 patients with AATD in stable phase. The patients' mean age was 51 years (SD 5.2); mean FEV1% was 35.5% (SD 15%). IL-6 and SRIL-6 concentrations were compared with those of 23 non-AATD patients with COPD but with similar changes in lung function (mean age 63 years, SD 10.1; FEV1% 38.3%, SD 11%). The AADT patients had mean IL-6 concentrations of 4.7 pg/mL (interquartile range [IR( 4.0) and RSIL-6 levels of 129.1 ng/mL (IR 31.5). The COPD patients had IL-6 concentrations of 4.1 pg/mL (IR 4.2) and SRIL-6 levels of 140.8 ng/mL (IR 71). No significant differences between the AADT group and the COPD group were observed for either cytokine (non-parametric Mann Whitney U test, p > 0.05). Only one AADT patient had an IL-6 concentration that was higher than normal. In conclusion, the serum IL-6 and SRIL-6 concentrations of patients with AADT are not different from those of patients with COPD, similarly altered respiratory function and normal alpha-1 antitrypsin levels. These results do not point to a role for alpha-1 antitrypsin in systemic inflammatory stimulation in patients with AADT.     

Aldosterone as a mediator in cardiovascular injury

The renin-angiotensin-aldosterone system plays a central role in the development of hypertension and the progression of end-organ damage. Although angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists can initially suppress plasma aldosterone, it is now well established that aldosterone escape may occur, whereby aldosterone levels return to or exceed baseline levels. The classic effects of aldosterone relate mainly to its action on epithelial cells to regulate water and electrolyte balance. However, blood pressure reduction or fluid loss could not account for the results of the Randomized Aldactone Evaluation Study, which showed that a low dose of spironolactone in addition to conventional therapy could decrease the overall risk of mortality by 30% among patients with severe congestive heart failure. The action of aldosterone at nonepithelial sites in the brain, heart, and vasculature is consistent with the presence of mineralocorticoid receptors in these tissues. Aldosterone has a number of deleterious effects on the cardiovascular system, including myocardial necrosis and fibrosis, vascular stiffening and injury, reduced fibrinolysis, endothelial dysfunction, catecholamine release, and production of cardiac arrhythmias. Several studies have now shown vascular and target-organ protective effects of aldosterone receptor antagonism in the absence of significant blood pressure lowering, consistent with a major role for endogenous mineralocorticoids as mediators of cardiovascular injury. The advent of selective aldosterone receptor antagonists such as eplerenone should prove of great therapeutic value in the prevention of cardiovascular disease and associated end-organ damage.     

Chlamydiae as etiologic agents in chronic undifferentiated spondylarthritis

Objective

The majority of patients with Chlamydia‐induced reactive arthritis do not present with the classic triad of arthritis, conjunctivitis/iritis, and urethritis. Moreover, acute chlamydial infections are often asymptomatic. The aim of the present study was to assess the prevalence of synovial Chlamydia trachomatis and Chlamydia pneumoniae infections in patients with chronic undifferentiated spondylarthritis (uSpA).

Methods

Study patients met the European Spondylarthropathy Study Group criteria for SpA, without evidence of ankylosing spondylitis, psoriasis, inflammatory bowel disease, or preceding dysentery. Symptoms were present for ≥6 months. Each patient underwent a synovial biopsy; tissue and concomitantly obtained peripheral blood mononuclear cells (PBMCs) were analyzed by polymerase chain reaction (PCR) for C trachomatis and C pneumoniae DNA. Other data collected on the day of the biopsy included standard demographic information and medical history, including any known history of C trachomatis or C pneumoniae. Physical examination (including joint count, evaluation for dactylitis and/or enthesitis, and skin examination) and HLA–B27 typing were performed. Synovial tissue (ST) samples from 167 patients with osteoarthritis (OA) were used as controls.

Results

Twenty‐six patients met the entry criteria and underwent synovial biopsy (25 knee, 1 wrist). Sixteen of them (62%) were positive for C trachomatis and/or C pneumoniae DNA (10 for C trachomatis, 4 for C pneumoniae, and 2 for both). PCR analysis of ST revealed the presence of Chlamydia significantly more frequently in patients with uSpA than in OA controls (P < 0.0001). No specific clinical characteristics differentiated Chlamydia‐positive from Chlamydia‐negative patients. PBMCs from 4 of the 26 uSpA patients (15%) were positive for Chlamydia, and Chlamydia was found in ST from 2 of these 4 patients. No significant correlation between PCR positivity and HLA–B27 positivity was found.

Conclusion

The frequency of Chlamydia‐positive ST samples, as determined by PCR, was found to be significantly higher in patients with uSpA than in patients with OA. Our results suggest that in many patients with uSpA, chlamydial infection, which is often occult, may be the cause.

     

Inflammation surrounding the vertebral spinous processes as spondylarthritis in Behçet’s disease

Abstract

Here, we present two Behçet’s disease (BD) patients with an uncommon complication: inflammation surrounding the spinous processes revealed by positron emission tomography/computed tomography (PET/CT). Both patients were treated successfully with 20 mg of prednisolone daily. Whether BD should be considered a form of spondylarthritis remains an open question. However, inflammation around the spinous processes should be regarded as a possible uncommon finding of seronegative spondyloarthropathy (SpA) in BD patients.     

Identification of a candidate human neurohematopoietic stem-cell population

It was recently reported that transplantation of clonally derived murine neurosphere cells into sublethally irradiated allogeneic hosts leads to a donor-derived hematopoietic reconstitution. The confirmation of the existence of a common neurohematopoietic stem cell in the human brain will have a significant effect on stem cell research and on clinical transplantation. Here, it is demonstrated that the human fetal brain contains separate but overlapping epidermal growth factor (EGF)-responsive and basic fibroblast growth factor (FGF-2)-responsive neural stem cells. The majority (> 85%) of cells within these EGF- and/or FGF-2-generated neurospheres express characteristic neural stem/progenitor cell markers including nestin, EGF receptor, and FGF-2 receptor. These neural stem cells can be continuously passaged in vitro, and demonstrate a constant 20-fold expansion in every passage for up to the fifth passage (the longest period that has been carried out in the authors' laboratory). These neural stem cells are multipotential for neurons, astrocytes, and oligodendrocytes. After transplantation into SCID-hu mice, all neural stem cells, regardless of passages, culture conditions, and donors, are able to establish long-term hematopoietic reconstitution in the presence of an intact human bone marrow microenvironment.     

Akt as a mediator of cell death

Protein kinase B/Akt possesses prosurvival and antiapoptotic activities and is involved in growth factor-mediated neuronal protection. In this study we establish Akt deactivation as a causal mediator of cell death. Akt deactivation occurs in multiple models of cell death including N-methyl-d-aspartate excitotoxicity, vascular stroke, and nitric oxide (NO)- and hydrogen peroxide (H2O2)-elicited death of HeLa, PC12, and Jurkat T cells. Akt deactivation characterizes both caspase-dependent and -independent cell death. Conditions rescuing cell death, such as treatment with poly(ADP-ribose) polymerase or NO synthase inhibitors and preconditioning with sublethal concentrations of N-methyl-d-aspartate, restore Akt activity. Infection of neurons with adenovirus expressing constitutively active Akt prevents excitotoxicity, whereas phosphatidylinositol 3-kinase inhibitors or infection with dominant negative Akt induce death of untreated neuronal cells.     

Association study of PHOX2B as a candidate gene for Hirschsprung's disease

BACKGROUND: Hirschsprung's disease (HSCR) is a congenital disorder characterised by an absence of ganglion cells in the nerve plexuses of the lower digestive tract. Manifestation of the disease has been linked to mutations in genes that encode the crucial signals for the development of the enteric nervous system-the RET and EDNRB signalling pathways. The Phox2b gene is involved in neurogenesis and regulates Ret expression in mice, in which disruption of the Phox2b results in a HSCR-like phenotype. AIMS: To investigate the contribution of PHOX2B to the HSCR phenotype. METHODS: Using polymerase chain reaction amplification and direct sequencing, we screened PHOX2B coding regions and intron/exon boundaries for mutations and polymorphisms in 91 patients with HSCR and 71 ethnically matched controls. Seventy five HSCR patients with no RET mutations were independently considered. Haplotype and genotype frequencies were compared using the standard case control statistic. RESULTS: Sequence analysis revealed three new polymorphisms: two novel single nucleotide polymorphisms (A-->G(1364); A-->C(2607)) and a 15 base pair deletion (DEL(2609)). Statistically significant differences were found for A-->G(1364). Genotypes comprising allele G were underrepresented in patients (19% v 36%; chi(2)=9.30; p=0.0095 and 22% v 36%; chi(2)=7.38; p=0.024 for patients with no RET mutations). Pairwise linkage disequilibrium (LD) analysis revealed no LD between physically close polymorphisms indicating a hot spot for recombination in exon 3. CONCLUSION: The PHOX2B A-->G(1364) polymorphism is associated with HSCR. Whether it directly contributes to disease susceptibility or represents a marker for a locus in LD with PHOX2B needs further investigation. Our findings are in accordance with the involvement of PHOX2B in the signalling pathways governing the development of enteric neurones.     

Hormonal and mediator correlations in type A personality as a risk factor in ischemic heart disease

Adrenaline and noradrenaline excretion in 24-hour urine and blood ACTH levels were examined with respect to behavior types in young people in the course of adaptation to lasting psychoemotional and physical stress exposure. The individuals of behavioral type A showed significantly increased noradrenaline excretion with daily urine and serum ACTH levels.     

Antibodies to peptidoglycan in patients with spondylarthritis: a clue to disease aetiology?

Although the aetiology of the spondylarthritic diseases, ankylosing spondylitis and Reiter's syndrome, is obscure, a clue to the pathogenesis might be an animal model, adjuvant arthritis. Rats with this disease develop a spectrum of pathology with marked similarity to the spondylarthritides. Since peptidoglycan, a major cell wall component of most bacteria is causally implicated in adjuvant arthritis, we sought evidence that peptidoglycan exposure accompanies both Reiter's syndrome and ankylosing spondylitis. Antibodies to the D-Ala-D-Ala moiety of peptidoglycan were measured by a sensitive and specific ELISA. Antibodies were elevated significantly in patients with ankylosing spondylitis or Reiter's syndrome, but not in patients with rheumatoid arthritis or degenerative joint disease in comparison with normal controls. The findings should be considered preliminary, since only a minority of patients had increased antibody titres. However, the findings are compatible with the hypothesis that peptidoglycan is causally related to spondylarthritis. Antibodies to other moieties in the peptidoglycan molecule might be a more sensitive test for significant exposure.