Systemic sclerosis (SSc) is characterized by extensive collagen deposition, microvasculopathy and autoantibodies. All three features can be promoted by activation of T cells and B cells. T cells are of Th2 type producing profibrotic cytokines IL-4 and IL-13 and inducing dendritic cell maturation that promotes Th2 response. B cells are overactivated and promote fibrosis by autoantibodies that activate fibroblasts or inhibit the degradation of extracellular matrix. They also promote fibrosis by cell-cell contact with fibroblasts or dendritic cells. B cells, through autoantibodies, may promote vasoconstriction and obliterative vasculopathy. They may also sustain activation of T cells by functioning as antigen-presenting cells. An immunoregulatory subset of B cells, namely IL-10-producing Bregs, is decreased in SSc. Finally, B cells have a critical role in animal models of SSc. All this evidence suggests an important role for B cells in the pathogenesis of SSc and makes B cells a potential target for therapeutic intervention in this disease. 

 

Background: Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by disturbance of the innate and adaptive immune systems with the production of autoantibodies by stimulated B lymphocytes. The BLyS protein (B lymphocyte stimulator) is secreted mainly by monocytes and activated T cells and is responsible for the proliferation, maturation and survival of B cells.

Objectivs: To study sera BLyS level and its clinical significance in Israeli lupus patients over time.

Methods: The study population included 41 lupus patients (8 males, 33 females; mean age 35.56 ± 15.35 years) and 50 healthy controls. The patients were followed for 5.02 ± 1.95 years. We tested 221 lupus sera (mean 5.4 samples/patient) and 50 normal sera for BLyS levels by a capture ELISA. Disease activity was determined by the SLEDAI score.

Results: Sera BLyS levels were significantly higher in SLE patients than in controls (3.37 ± 3.73 vs. 0.32 ± 0.96 ng/ml, P < 0.05). BLyS levels were high in at least one sera sample in 80.5% of the patients but were normal in all sera in the control group. There was no correlation between sera BLyS and anti-ds-DNA autoantibody levels. BLyS levels fluctuated over time in sera of lupus patients with no significant correlation to disease activity.

Conclusions: Most of our lupus patients had high sera BLyS levels, suggesting a role for BLyS in the pathogenesis and course of SLE. Our results support the current novel approach of targeting BLyS (neutralization by antibodies or soluble receptors) in the treatment of active lupus patients.

High mobility group box 1 is a nuclear protein participating in chromatin architecture and transcriptional regulation. When released from cells, HMGB1[1] can also act as a pro-inflammatory mediator or alarmin. Upon stimulation with lipopolysaccharides or tumor necrosis factor-alpha, HMGB1 is secreted from certain cells such as monocytes/macrophages and fosters inflammatory responses. In addition, HMGB1 is passively released from necrotic cells and mediates inflammation and immune activation. In contrast, during apoptotic cell death, nuclear HMGB1 gets tightly attached to hypo-acetylated chromatin and is not released into the extracellular milieu, thereby preventing an inflammatory response. There is accumulating evidence that extracellular HMGB1 contributes to the pathogenesis of many inflammatory diseases, including autoimmune diseases. Increased concentrations of HMGB1 have been detected in the synovial fluid of patients with rheumatoid arthritis. In animal models of RA[2], HMGB1 appears to be crucially involved in the pathogenesis of arthritis, since neutralization of HMGB1 significantly ameliorates the disease. Also, in the serum and plasma of patients with systemic lupus erythematosus we detected substantial amounts of HMGB1, which may contribute to the disease process. However, investigations of blood concentrations of HMGB1 and its relevance in human diseases are hindered by the lack of reliable routine test systems.

Chronic fatigue syndrome is a heterogeneous disorder with unknown pathogenesis and etiology, characterized by disabling fatigue, difficulty in concentration and memory, and concomitant skeletal and muscular pain. Several mechanisms have been suggested to play a role in CFS[1], such as excessive oxidative stress following exertion, immune imbalance characterized by decreased natural killer cell and macrophage activity, immunoglobulin G subclass deficiencies (IgG-1[2], IgG-3) and decreased serum concentrations of complement component. Autoantibodies were also suggested as a possible factor in the pathogenesis of CFS. Recent studies indicate that anti-serotonin, anti-microtubule-associated protein 2 and anti-muscarinic cholinergic receptor 1 may play a role in the pathogenesis of CFS. It has been demonstrated that impairment in vasoactive neuropeptide metabolism may explain the CFS symptoms

Background: Seasickness is thought to result from conflicting inputs from the vestibular, visual and somatosensory systems. The otolithic organs, which are responsible for the sensation of linear acceleration and tilt, are important in the pathogenesis of seasickness. Vestibular evoked myogenic potentials test is an objective evaluation of saccular function.

Objective: To examine whether saccular function is related to the pathogenesis of seasickness.

Methods: VEMP1 was performed in 10 subjects susceptible to seasickness and in 14 non-susceptible subjects.

Results: Bilateral VEMP responses were obtained in 7 (50%) of the non-susceptible subjects and 1 (10%) of the susceptible subjects. No differences were found between the groups in P13 and N23 wave latencies, amplitudes, N13-P23 inter-peak latencies, and peak-to-peak asymmetry ratios. More subjects in the susceptible group had asymmetry ratios > 35%.   

Conclusions: The attenuated saccular response might be explained in the context of the neural-mismatch theory and/or the subjective vertical theory, as reflecting an adaptation effort to sea conditions. A larger study is necessary to determine whether a statistically significant difference in VEMP responses exists between seasickness-susceptible and non-susceptible subjects.
 

Background: Decreased heparan sulfate proteoglycan content of the glomerular basement membrane has been described in proteinuric patients with diabetic nephropathy. Heparanase is an endo-b-D-glucuronidase that cleaves negatively charged heparan sulfate side chains in the basement membrane and extracellular matrix.

Objectives: To investigate whether urine from type I diabetic patients differs in heparanase activity from control subjects and whether resident glomerular cells could be the source of urinary heparanase.

Methods: Using soluble ³⁵S-HSPG[1] and sulfate-labeled extracellular matrix we assessed heparanase activity in human glomerular epithelial cells, rat mesangial cells, and urine from 73 type I diabetic patients. Heparanase activity resulted in the conversion of a high molecular weight sulfate-labeled HSPG into heparan sulfate degradation fragments as determined by gel filtration analysis.

Results: High heparanase activity was found in lysates of both epithelial and mesangial cells. Immunohistochemical staining localized the heparanase protein to both glomeruli capillaries and tubular epithelium. Heparanase activity was detected in the urine of 16% and 25% of the normoalbuminuric and microalbuminuric diabetic patients, respectively. Urine from 40 healthy individuals did not posses detectable heparanase. Urinary heparanase activity was associated with worse glycemic control.

Conclusion: We suggest that heparanase enzyme participates in the turnover of glomerular HSPG. Hyperglycemia enhances heparanase activity and/or secretion in some diabetic patients, resulting in the loss of albumin permselective properties of the GBM[2].

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[1] HSPG = heparan sulfate proteoglycan

[2] GBM = glomerular basement membrane

Systemic infection or inflammation causes a decrease in intestinal iron absorption and impairs the release of recycled iron from macrophages. Decreased availability of iron may deny this essential element to invading pathogens and may inhibit their multiplication and other metabolic processes but also results in anemia of chronic disease. This article reviews recent discoveries that shed light on the regulation of iron metabolism during infection and iron overload, and point to the central role of a newly discovered peptide, hepcidin. Evidence to date indicates that hepcidin is a negative regulator of intestinal iron absorption, placental iron transport, and the release of iron from macrophages that recycle iron from senescent red cells. It may also be the central mediator of iron sequestration during infections and inflammatory states and the mediator of anemia of chronic disease. Rapid progress in this area is a good example of the beneficial effects of improvements in peptide analysis and chemistry, advances in genomics, and the increasing use of transgenic mice to determine the function of newly discovered genes and proteins.

The formerly prevalent concept that intact autoantibodies could not penetrate into viable cells has been defeated by a large amount of experimental findings and clinical observations that indicate otherwise. The penetration of autoantibodies into living cells seems to participate in the pathogenesis of diverse autoimmune diseases, but it may also play a physiological role in healthy individuals. Although the fine mechanisms of the phenomenom remain to be elucidated, the potential use of penetrating autoantibodies as vectors to deliver molecules into cells, with diverse therapeutic purposes, has gained growing interest during the last few years.