Presence and active synthesis of the 67 kDa elastin-receptor in human circulating white blood cells

Molecular Targets and Related Biologic Activities of Fucoidan: A Review

Fucoidan-a marine natural active polysaccharide derived from brown algae with a variety of medicinal activities and low toxicity-has been used as clinical drug for renal diseases for nearly 20 years. The pharmacological mechanism of fucoidan has been well-investigated, based on target molecules and downstream signaling pathways. This review summarizes some important molecular targets of fucoidan and its related biologic activities, including scavenger receptor (SR), Toll-like receptors (TLRs), C-type lectin (CLEC) and some newly found target molecules, which may be beneficial for further understanding the pharmacological mechanism of fucoidan and discovering its new functions, as well as developing related clinical or adjuvant drugs and functional preparations.

The role of elastin peptides in modulating the immune response in aging and age-related diseases

It is now well accepted that aging is associated with the occurrence of a low-grade inflammation called Inflamm-aging. This leads to the imbalance between the various mediators of the inflammatory response in favour of the pro-inflammatory response represented by pro-inflammatory cytokines and oxidative stress. The question that arises, and is still under investigation, what is the origin of the driving force leading to these changes. One of the current hypotheses is that chronic stimulation of the immune system contributes to the pro-inflammatory shift. The chronic stimulation can be of viral origin such as cytomegalovirus, from tumor antigens or from other sources such as the extracellular matrix, especially from elastin fibres and collagens. Aging and various inflammatory diseases such as atherosclerosis, abdominal aortic aneurysms, chronic obstructive pulmonary diseases (COPD), cancer and type 2 diabetes are characterized by the destruction of elastin fibers and the consequent generation of elastin peptides which are biologically active. This review will describe the putative contribution of elastin peptides to inflamm-aging and extend on their role on immunosenescence, as well as on age-associated chronic inflammatory diseases.

Hypertrophy of the lumbar ligamentum flavum is associated with inflammation-related TGF-β expression

BACKGROUND

Despite the significance of hypertrophy of the ligamentum flavum (HLF) in the disease progress of neurogenic claudication, the cellular mechanisms underlying the gradual fibrotic thickening of the ligamentum flavum remain poorly understood. The aim of our study was to get insight into the contribution of inflammatory mechanisms to the development of hypertrophy.

METHODS

Specimens of hypertrophied ligamenta flava were obtained at surgery from 20 patients with acquired lumbar osteoligamentous spinal canal stenosis from the central part of the ligament. Paraffin sections were stained with hematoxylin and eosin and Elastica van Gieson to evaluate extracellular matrix architecture, and immunohistochemistry was performed to characterize the inflammatory reaction and the sources of transforming growth factor beta (TGF-β) expression. Sections of normal ligamenta flava obtained from corresponding anatomical sites and stained in parallel served as a control.

RESULTS

HLF was characterized by a considerable distortion of the elastic matrix and fibrotic transformation by extracellular collagen deposition. All specimens showed highly inflammatory cellular infiltrates confined to regions exhibiting marked degeneration of the elastic matrix composed mainly of macrophages, scattered T lymphocytes, and neovascularization, thus representing a chronic inflammation. Surprisingly, macrophages as well as vascular endothelial cells but not fibroblasts showed a strong expression of TGF-β, a strong inducer of extracellular collagen deposition.

CONCLUSIONS

Macrophages were identified as a major cellular source of TGF-β in advanced HLF and may perpetuate further hypertrophy. This finding suggests that modulating the immune response locally or systemically could prove to be effective for impeding the disease progress.

Soluble elastin decreases in the progress of atheroma formation in human aorta

BACKGROUND

The serum levels of soluble elastin increase in patients with aortic dissection, but its distribution and characteristics are unclear.

METHODS AND RESULTS

The 173 aortic specimens were categorized into 4 groups under microscopy (non-atherosclerotic aorta, n=13; fiber-rich plaque, n=77; lipid-rich plaque, n=66; ruptured plaque, n=17). Soluble elastin was abundant within the intima of both the non-atherosclerotic aorta and fiber-rich plaque, rather than in the media, and was decreased within the intima of lipid-rich and ruptured plaques. Soluble elastin levels decreased with progress of atherosclerosis (6.0 +/-0.3 microg/mg protein in non-atherosclerotic aorta; 5.8 +/-0.2 microg/mg protein in fiber-rich plaque; 4.9 +/-0.2 microg/mg protein in lipid-rich plaque; 2.8 +/-0.4 microg/mg protein in ruptured plaque, P<0.05). As well, both matrix metalloprotease-9 activity and elastin mRNA expression showed inverse distribution against soluble elastin (r=0.437, P<0.0001; r=0.186, P<0.05, respectively). Multivariable analysis revealed a decrease in the level of soluble elastin in ruptured plaque (2.8 +/-0.4 microg/mg protein in ruptured plaque, n=18; 5.5 +/-0.2 microg/mg protein in non-ruptured plaque, n=155, P<0.01). Furthermore, western blot showed soluble elastin consists of heterogeneous molecular pattern proteins.

CONCLUSIONS

Both the synthesis and degradation of elastin may be enhanced in active atherosclerotic lesions.

Fragments of extracellular matrix as mediators of inflammation

Classically, the extracellular matrix (ECM) was viewed as a supporting structure for stabilizing the location of cells in tissues and for preserving the architecture of tissues. This conception has changed dramatically over the past few decades with discoveries that ECM has profound influences on the structure, viability, and functions of cells. Much of the data supporting this new paradigm has been obtained from studies of normal and pathological structural cells such as fibroblasts, smooth muscle cells, and malignant cells, as, for example, breast cancer epithelial cells. However, there has also been recognition that effects of ECM on cells extend to inflammatory cells. In this context, attention has been drawn to fragments of ECM components. In this review, we present information supporting the concept that proteolytic fragments of ECM affect multiple functions and properties of inflammatory and immune cells. Our focus is particularly upon neutrophils, monocytes, and macrophages and fragments derived from collagens, elastin, and laminins. Hyaluronan fragments, although they are not products of proteolysis, are also discussed, as they are a notable example of ECM fragments that exhibit important effects on inflammatory cells. Further, we summarize some exciting recent developments in this field as a result of mouse models in which defined ECM fragments and their receptors are clearly implicated in inflammation in vivo. Thus, this review underscores the idea that proteolysis of ECM may well have implications that go beyond modifying the structural environment of cells and tissues.

Elastin receptor (spliced galactosidase) occupancy by elastin peptides counteracts proinflammatory cytokine expression in lipopolysaccharide-stimulated human monocytes through NF-kappaB down-regulation

In inflammatory diseases, strong release of elastinolytic proteases results in elastin fiber degradation generating elastin peptides (EPs). Chemotactic activity for inflammatory cells was, among wide range of properties, the former identified biological activity exerted by EPs. Recently, we demonstrated the ability of EPs to favor a Th1 cytokine (IL-2, IFN-gamma) cell response in lymphocytes and to regulate IL-1beta expression in melanoma cells. We hypothesized that EPs might also influence inflammatory cell properties by regulating cytokine expression by these cells. Therefore, we investigated the influence of EPs on inflammatory cytokine synthesis by human monocytes. We evidenced that EPs down-regulated both at the mRNA and protein levels the proinflammatory TNF-alpha, IL-1beta, and IL-6 expression in LPS-activated monocytes. Such negative feedback loop could be accounted solely for EP-mediated effects on proinflammatory cytokine production because EPs did not affect anti-inflammatory IL-10 or TGF-beta secretion by LPS-activated monocytes. Furthermore, we demonstrated that EP effect on proinflammatory cytokine expression by LPS-stimulated monocytes could not be due either to a decrease of LPS receptor expression or to an alteration of LPS binding to its receptor. The inhibitory effects of EPs on cytokine expression were found to be mediated by receptor (spliced galactosidase) occupancy, as being suppressed by lactose, and to be associated with the decrease of NF-kappaB-DNA complex formation. As a whole, these results demonstrated that EP/spliced galactosidase interaction on human monocytes down-regulated NF-kappaB-dependent proinflammatory cytokine expression and pointed out the critical role of EPs in the regulation of inflammatory response.

Impairment of SHP-1 down-regulation in the lipid rafts of human neutrophils under GM-CSF stimulation contributes to their age-related, altered functions

It has been shown that the functions and the rescue from apoptosis by proinflammatory mediators of polymorphonuclear leukocytes (PMN) tend to diminish with aging. Here, we investigated the role of protein tyrosine phosphatases (PTP), especially Src homology domain-containing protein tyrosine phosphatase-1 (SHP-1), in the age-related, altered PMN functions under granulocyte macrophage-colony stimulating factor (GM-CSF) stimulation. The inhibition of PTP suggested a differential effect of GM-CSF on phosphatase activity in modulating PMN functions with aging. The down-regulation of phosphatase activity of immunopurified SHP-1 from lipid rafts of PMN of young donors was found significantly altered at 1 min of stimulation with aging. In young donors, SHP-1 is displaced from lipid rafts at 1 min of stimulation, whereas in the elderly, SHP-1 is constantly present. We assessed in PMN lipid rafts the phosphorylation of tyrosine and serine residues of SHP-1, which regulates its activity. We observed an alteration in the phosphorylation of tyrosine and serine residues of SHP-1 in PMN of elderly subjects, suggesting that GM-CSF was unable to inhibit SHP-1 activity by serine phosphorylation. GM-CSF activates Lyn rapidly, and we found alterations in its activation and translocation to the lipid rafts with aging. We also demonstrate that SHP-1 in the PMN of elderly is constantly recruited to Lyn, which cannot be relieved by GM-CSF. In contrast, in the young, the resting recruitment could be relieved by GM-CSF. Our results suggest an alteration of the SHP-1 modulation by GM-CSF in lipid rafts of PMN with aging. These alterations could contribute to the decreased GM-CSF effects on PMN.