Association of mannose-binding lectin gene polymorphism but not of mannose-binding serine protease 2 with chronic severe aortic regurgitation of rheumatic etiology

N-Acetylglucosamine (GlcNAc) is the major immunoepitope of group A streptococcal cell wall carbohydrates. Antistreptococcal antibodies cross-reactive with anti-GlcNAc and laminin are present in sera of patients with rheumatic fever. The cross-reactivity of these antibodies with human heart valvular endothelium and the underlying basement membrane has been suggested to be a possible cause of immune-mediated valve lesion. Mannose-binding lectin (MBL) encoded by the MBL2 gene, a soluble pathogen recognition receptor, has high affinity for GlcNAc. We postulated that mutations in exon 1 of the MBL2 gene associated with a deficient serum level of MBL may contribute to chronic severe aortic regurgitation (AR) of rheumatic etiology. We studied 90 patients with severe chronic AR of rheumatic etiology and 281 healthy controls (HC) for the variants of the MBL2 gene at codons 52, 54, and 57 by using a PCR-restriction fragment length polymorphism-based method. We observed a significant difference in the prevalence of defective MBL2 alleles between patients with chronic severe AR and HC. Sixteen percent of patients with chronic severe AR were homozygotes or compound heterozygotes for defective MBL alleles in contrast to 5% for HC (P = 0.0022; odds ratio, 3.5 [95% confidence interval, 1.6 to 7.7]). No association was detected with the variant of the MASP2 gene. Our study suggests that MBL deficiency may contribute to the development of chronic severe AR of rheumatic etiology.     

Myelin basic protein-specific T lymphocytes proliferation and programmed cell death in demyelinating diseases

A dynamic equilibrium between proliferation and programmed cell death (PCD) of auto-reactive T lymphocytes plays a pivotal role in the prevention of autoimmune diseases. We analyzed T lymphocytes myelin basic protein (MBP)-specific PCD and proliferation in demyelinating diseases. Results showed that MBP-specific PCD was significantly decreased in CD4+ and CD8+ T lymphocytes of progressive multifocal leukoencephalopathy (PML), not determined leukoencephalopathy (NDLE), and acute MS (AMS) patients compared to patients with stable MS (SMS) and healthy controls. MBP-specific proliferation/PCD rates were high in CD4+ T lymphocytes of PML, NDLE, and AMS patients, and in CD8+ T cells of PML and AMS individuals alone. Alterations of the balance between MBP-specific proliferation and PCD are present in demyelinating diseases and could play a major role in the pathogenesis of these diseases.     

An antimetastatic role for decorin in breast cancer

Decorin, a member of the small leucine-rich proteoglycan gene family, down-regulates members of the ErbB receptor tyrosine kinase family and attenuates their signaling, leading to growth inhibition. We investigated the effects of decorin on the growth of ErbB2-overexpressing mammary carcinoma cells in comparison with AG879, an established ErbB2 kinase inhibitor. Cell proliferation and anchorage-independent growth assays showed that decorin was a potent inhibitor of breast cancer cell growth and a pro-apoptotic agent. When decorin and AG879 were used in combination, the inhibitory effect was synergistic in proliferation assays but only additive in both colony formation and apoptosis assays. Active recombinant human decorin protein core, AG879, or a combination of both was administered systemically to mice bearing orthotopic mammary carcinoma xenografts. Primary tumor growth and metabolism were reduced by approximately 50% by both decorin and AG879. However, no synergism was observed in vivo. Decorin specifically targeted the tumor cells and caused a significant reduction of ErbB2 levels in the tumor xenografts. Most importantly, systemic delivery of decorin prevented metastatic spreading to the lungs, as detected by novel species-specific DNA detection and quantitative assays. In contrast, AG879 failed to have any effect. Our data support a role for decorin as a powerful and effective therapeutic agent against breast cancer due to its inhibition of both primary tumor growth and metastatic spreading.     

Gr1(+) inflammatory monocytes are required for mucosal resistance to the pathogen Toxoplasma gondii

The enteric pathogen Toxoplasma gondii is controlled by a vigorous innate T helper 1 (Th1) cell response in the murine model. We demonstrated that after oral infection, the parasite rapidly recruited inflammatory monocytes [Gr1(+) (Ly6C(+), Ly6G(-)) F4/80(+)CD11b(+)CD11c(-)], which established a vital defensive perimeter within the villi of the ileum in the small intestine. Mice deficient of the chemokine receptor CCR2 or the ligand CCL2 failed to recruit Gr1(+) inflammatory monocytes, whereas dendritic cells and resident tissue macrophages remained unaltered. The selective lack of Gr1(+) inflammatory monocytes resulted in an inability of mice to control replication of the parasite, high influx of neutrophils, extensive intestinal necrosis, and rapid death. Adoptive transfer of sorted Gr1(+) inflammatory monocytes demonstrated their ability to home to the ileum in infected animals and protect Ccr2(-/-) mice, which were otherwise highly susceptible to oral toxoplasmosis. Collectively, these findings illustrate the critical importance of inflammatory monocytes as a first line of defense in controlling intestinal pathogens.     

Micropapillary carcinoma of the breast with necrosis-like cell death: a case report

A primary invasive micropapillary carcinoma of the breast in a 46-year-old woman is reported. Histologically, it was composed predominantly of papillary tumor cell clusters without fibrovascular cores, surrounded by a clear space. Tumor cells were positive for cytokeratin (CK) 7, estrogen receptor (ER), and progesterone receptor (PR), but negative for p53, CK 20, CD34, c-Erb-B2, CK5, epidermal growth factor receptor (EGFR), vimentin, and c-kit. MUC1 expression was found at the reversed apical membrane of neoplastic cell clusters. Accordingly, electron microscopy showed the lack of basement membrane and presence of microvilli at the basal surface of the tumor cells. Moreover, ultrastructural examination revealed single tumor cell death characterized by patchy condensations of chromatin throughout the nucleus. These nuclear alterations were associated with the occurrence of empty cytoplasmic vacuoles, conferring a necrosis-like phenotype to this cell death. Alternative programmed cell deaths are reviewed and their morphologic distinction is discussed.     

C-338A polymorphism of the endothelin-converting enzyme (ECE-1) gene and the susceptibility to sporadic late-onset Alzheimer's disease and coronary artery disease

The human endothelin-converting enzyme (ECE) is involved in beta-amyloid synthesis and regulation of the endothelin-1 (ET-1) vasoconstricting peptide. We investigated the distribution of the C-338A polymorphism of the ECE-1b gene in sporadic late-onset Alzheimer's disease (LOAD) and in coronary artery disease (CAD) to verify its role in the onset of these two complex diseases. Two cohorts of 458 Italian Caucasian LOAD patients and 165 CAD patients were examined for the C-338A polymorphism and compared with respective control samples (260 and 106 subjects, respectively) . The A allele was less present in LOAD patients than in controls, but an at limits statistically significant difference was achieved only in subjects aged less than 80 years, where only the AA genotypes appeared to have a protective role against the onset of the sporadic LOAD. For the overall CAD sample the pattern was similar and significant differences were observed only in subjects non carrying the apolipoprotein E (APOE) e*4 allele, where the A allele carrying genotypes had a protective role against the onset of the disease.     

Autoimmunity in IgA deficiency: revisiting the role of IgA as a silent housekeeper

Both systemic and organ-specific autoimmune diseases are major manifestations of IgA deficiency (IgAD), the most common primary immunodeficiency. In addition, to discuss the clinical findings of IgAD patients, we proposed a hypothesis to explain the high association with autoimmune phenomena. Based on observations, interactions of monomeric IgA with FcalphaRI result in a partial phosphorylation of FcRgamma-associated FcalphaRI, notably in the immunoreceptor tyrosine-based activation motif (ITAM) inducing the recruitment of the SHP-1 tyrosine phosphatase. This leads to deactivation of several activating pathways of the immune system including immunoreceptors that bear ITAM motif and ITAM-independent receptors. Consequently, inflammatory reactions and auto-immune process would be prevented.     

Modulation of troponin C affinity for the thin filament by different cross-bridge states in skinned skeletal muscle fibers

In vertebrate skeletal muscle, the C-domain of troponin C (TnC) serves as an anchor; the N-domain regulates the position of troponin-tropomyosin on the thin filament after changes in intracellular Ca2+. Another type of thin-filament regulation is provided by cross-bridges. In this study, we use skinned fibers reconstituted with chicken recombinant TnC (rTnC) to examine TnC-thin filament affinity when cross-bridges containing different ligands are formed. Dissociation and equilibrium binding of apo-TnC (i.e., lacking divalent cations) under different conditions were monitored by a standard test for maximum tension (P (o)). After 10 min in low-Mg2+ relaxing solution, rTnC dissociation (i.e., tension loss) was 80% vs only 45% in rigor. In rigor, adding myosin subfragment 1 (S1) reduced dissociation approximately twofold, whereas stretching to reduce filament overlap increased dissociation to nearly the value for relaxed fibers. Dissociation of rTnC after addition of Pi or MgADP to form A.M.Pi or A.M.ADP cross-bridges was significantly greater than with rigor (A.M) bridges. The increase in P (o) during equilibration with different concentrations of rTnC showed that the affinity for rTnC binding to the thin filament increased progressively with stronger cross-bridges: rTnC concentrations for half-maximal reconstitution (K (0.5)) were 8.1, 3.7, 2.9, and 1.1 microM for A + M.ADP.Pi, A.M.Pi, A.M, and A.M + S1. Cross-bridges containing MgADP(-) (A.M.ADP) were also less effective than rigor bridges in promoting rTnC binding. We conclude that cross-bridge state and number both modulate TnC affinity for the thin filament and that the TnC C-domain is a central element in this pathway.