A study of elastic tissue and actinic radiation in "aging," temporal arteritis, polymyalgia rheumatica, and atherosclerosis. The actinic storm in the modern world

A seasonal pattern in the onset of polymyalgia rheumatica and giant cell arteritis? A systematic review and meta-analysis

OBJECTIVES

Studies on the seasonality of onset of polymyalgia rheumatica (PMR) and giant cell arteritis (GCA) have shown conflicting results. The aim of this systematic literature review and meta-analysis is to determine from aggregated data whether there is a seasonal distribution for these diseases.

METHODS

A literature search was performed using Pubmed Central and Embase scientific databases. The incidences per 6-month periods, season or month of onset, that were reported in the studies were summarised in tables considering the two diseases as separate conditions or together. The Incidence Rate Ratio (IRR) for the cold period versus the warm period was pooled across studies by random effects meta-analysis weighed by inverse variance. Funnel plots and Egger test were used to explore possible publication biases. A sensitivity analysis was performed to weigh articles with a disproportionate number of patients compared to the rest.

RESULTS

In the scientific literature 22 suitable papers were found: 6 on PMR with 803 patients, 11 on GCA with 2,807 patients, and 5 studies considering both diseases with 19,613 patients. There was considerable heterogeneity amongst studies regarding their quality, the classification criteria used, and the definition of onset of symptoms. No seasonal aggregation was found for GCA and PMR. The pooled IRR estimate of the meta-analysis (1.13[0.89,1.36]) showed a non-significant, higher frequency of diseases onset in the warm season.

CONCLUSIONS

Our meta-analysis did not confirm a seasonal onset for PMR and GCA.

Linearized solar elastosis of the legs: A novel presentation and review of the literature

There exists a spectrum of solar elastotic variants based on the clinical and histopathologic findings. We present here a peculiar case of solar elastosis that is unusual in its anatomic location, relative lack of background actinic damage, and pattern of linearization. Its presentation suggests that other factors in addition to ultraviolet radiation may play a role in the pathogenesis of solar elastosis.

Molecular Mechanisms of Stress-Responsive Changes in Collagen and Elastin Networks in Skin

Collagen and elastin networks make up the majority of the extracellular matrix in many organs, such as the skin. The mechanisms which are involved in the maintenance of homeostatic equilibrium of these networks are numerous, involving the regulation of genetic expression, growth factor secretion, signalling pathways, secondary messaging systems, and ion channel activity. However, many factors are capable of disrupting these pathways, which leads to an imbalance of homeostatic equilibrium. Ultimately, this leads to changes in the physical nature of skin, both functionally and cosmetically. Although various factors have been identified, including carcinogenesis, ultraviolet exposure, and mechanical stretching of skin, it was discovered that many of them affect similar components of regulatory pathways, such as fibroblasts, lysyl oxidase, and fibronectin. Additionally, it was discovered that the various regulatory pathways intersect with each other at various stages instead of working independently of each other. This review paper proposes a model which elucidates how these molecular pathways intersect with one another, and how various internal and external factors can disrupt these pathways, ultimately leading to a disruption in collagen and elastin networks.

Fingerprinting desmosine-containing elastin peptides

Elastin is a vital protein of the extracellular matrix of jawed vertebrates and provides elasticity to numerous tissues. It is secreted in the form of its soluble precursor tropoelastin, which is subsequently cross-linked in the course of the elastic fiber assembly. The process involves the formation of the two tetrafunctional amino acids desmosine (DES) and isodesmosine (IDES), which are unique to elastin. The resulting high degree of cross-linking confers remarkable properties, including mechanical integrity, insolubility, and long-term stability to the protein. These characteristics hinder the structural elucidation of mature elastin. However, MS(2) data of linear and cross-linked peptides released by proteolysis can provide indirect insights into the structure of elastin. In this study, we performed energy-resolved collision-induced dissociation experiments of DES, IDES, their derivatives, and DES-/IDES-containing peptides to determine characteristic product ions. It was found that all investigated compounds yielded the same product ion clusters at elevated collision energies. Elemental composition determination using the exact masses of these ions revealed molecular formulas of the type CxHyN, suggesting that the pyridinium core of DES/IDES remains intact even at relatively high collision energies. The finding of these specific product ions enabled the development of a similarity-based scoring algorithm that was successfully applied on LC-MS/MS data of bovine elastin digests for the identification of DES-/IDES-cross-linked peptides. This approach facilitates the straightforward investigation of native cross-links in elastin.

Environmental factors and stroke: A selective review

Despite numerous prior stroke risk factor investigations, much remains unknown about the effect of environmental factor changes on stroke incidence and mortality rates. Yet these data might be important for defining a number of measures to prevent stroke and for developing a greater understanding of the origin and incidence trends of stroke in different regions and populations. In this paper we review the current state of knowledge about certain environmental stroke risk factors.

Statin therapy does not seem to benefit giant cell arteritis

OBJECTIVE

Since statins interfere with a variety of immune-inflammatory pathways shared by atherosclerosis and giant cell arteritis (GCA), they might be potentially useful as adjunctive therapy to glucocorticosteroids in GCA. Our aim was to examine whether concomitant use of statins had any potential benefit in GCA.

METHODS

Retrospective follow-up study of an unselected population of 121 patients with GCA. A comparative analysis between patients with and without statin therapy was performed.

RESULTS

At the time of the GCA diagnosis, 30 patients (25%) had already been receiving statins and continued taking them during the corticosteroid treatment. No statistically significant reduction in the incidence of severe ischemic complications (including visual manifestations, jaw claudication, cerebrovascular accidents, ischemic heart disease, and limb claudication due to large artery stenosis) was observed in this group compared with the remaining patients. When we analyzed follow-up data, we found no significant differences between groups in terms of frequency of relapses, incidence of aortitis, and percentage of patients recovered from GCA. The duration of therapy and corticosteroids requirements among patients in permanent remission was similar in both groups.

CONCLUSION

We did not observe a significant benefit derived from the use of statins at low to moderate doses in the incidence of severe ischemia or the disease outcome.

Acquired disorders of elastic tissue: part I. Increased elastic tissue and solar elastotic syndromes

Elastic fibers in the extracellular matrix are an integral component of dermal connective tissue. The resilience and elasticity required for normal structure and function of the skin may be attributed to the network of elastic tissue. Advances in our understanding of elastic tissue physiology provide a foundation for studying the pathogenesis of elastic tissue disorders. Many acquired disorders are nevertheless poorly understood due to the paucity of reported cases. Several acquired disorders in which accumulation or elastotic degeneration of dermal elastic fibers produces prominent clinical and histopathologic features have recently been described. They include elastoderma, linear focal elastosis, and late-onset focal dermal elastosis and must be differentiated from better-known disorders, among them acquired pseudoxanthoma elasticum, elastosis perforans serpiginosa, and Favré-Racouchot syndrome. Learning objective At the conclusion of this learning activity, participants should understand the similarities and differences between acquired disorders of elastic tissue that are characterized by an increase in elastic tissue, as well as the spectrum of solar elastotic dermatoses.

Synchronous granulomatous cholecystitis and fibroelastosis of the gallbladder

We describe an unusual form of xanthogranulomatous cholecystitis in a 69-year-old man, with abundant intramural concrement formation and a local fibroelastosis of the adjacent interstitium and arteries. The gallbladder was obtained following resection of an adenocarcinoma of the gastro-esophageal junction without evidence of metastases. Only two cases of fibroelastosis of the gallbladder have previously been reported, and its pathogenesis is unknown. The influence of bile that leaked into the interstitium or a specific local tissue response to cytokines secreted by histiocytes are among the possible explanations for its development in our case.

Changes in Matrix Gene and Protein Expressions After Single or Repeated Exposure to One Minimal Erythemal Dose of Solar-simulated Radiation in Human Skin In Vivo

Damage to the skin extracellular matrix (ECM) is the hallmark of long-term exposure to solar UV radiation. The aim of our study was to investigate the changes induced in unexposed human skin in vivo after single or repeated (five times a week for 6 weeks) exposure to 1 minimal erythemal dose (MED) of UV solar-simulated radiation. Morphological and biochemical analyses were used to evaluate the structural ECM components and the balance between the degrading enzymes and their physiologic inhibitors. A three-fold increase in matrix metalloproteinase 2 messenger RNA (mRNA) (P < 0.02, unexposed versus exposed) was observed after both single and repeated exposures. Fibrillin 1 mRNA level was increased by chronic exposure (P < 0.02) and unaltered by a single MED. On the contrary, a single MED significantly enhanced mRNA levels of interleukin-1alpha (IL-1alpha), IL-1beta (P < 0.02) and plasminogen activator inhibitor-1 (P < 0.05). Immunohistochemistry demonstrated a significant decrease in Type-I procollagen localized just below the dermal-epidermal junction in both types of exposed sites. At the same location, the immunodetected tenascin was significantly enhanced, whereas a slight increase in Type-III procollagen deposits was also observed in chronically exposed areas. Although we were unable to observe any change in elastic fibers in chronically exposed buttock skin, a significant increase in lysozyme and alpha-1 antitrypsin deposits on these fibers was observed. These results demonstrate the existence of a differential regulation, after chronic exposure compared with an acute one, of some ECM components and inflammatory mediators.

Intrinsic aging vs. photoaging: a comparative histopathological, immunohistochemical, and ultrastructural study of skin

Cutaneous aging is a complex biological phenomenon affecting the different constituents of the skin. To compare the effects of intrinsic and extrinsic aging processes, a total of 83 biopsies were collected from sun-exposed and protected skin of healthy volunteers representing decades from the 1st to the 9th (6-84 years of age). Routine histopathology coupled with computer-assisted image analysis was used to assess epidermal changes. Immunoperoxidase techniques with antibodies against type I and type III collagens and elastin were used to quantitatively evaluate changes in collagen and elastic fibers and their ultrastructure was examined by transmission electron microscopy. Epidermal thickness was found to be constant in different decades in both sun-exposed and protected skin; however, it was significantly greater in sun-exposed skin (P = 0.0001). In protected skin, type I and III collagen staining was altered only after the 8th decade, while in sun-exposed skin the relative staining intensity significantly decreased from 82.5% and 80.4% in the 1st decade to 53.2% and 44.1% in the 9th decade, respectively (P = 0.0004 and 0.0008). In facial skin the collagen fiber architecture appeared disorganized after the 4th decade. The staining intensity of elastin in protected skin significantly decreased from 49.2% in the 1st decade to 30.4% in the 9th decade (P = 0.05), whereas in sun-exposed skin the intensity gradually increased from 56.5% in the 1st decade to 75.2% in the 9th decade (P = 0.001). The accumulated elastin in facial skin was morphologically abnormal and appeared to occupy the areas of lost collagen. Collectively, the aging processes, whether intrinsic or extrinsic, have both quantitative and qualitative effects on collagen and elastic fibers in the skin.

Bilateral temporal arteritis

Temporal arteritis is a giant cell arteritis that affects large- or medium-sized elastic arteries. Often, only 1 temporal artery is affected. We describe a patient with both temporal arteries being involved simultaneously. To our knowledge, this particular constellation has rarely been described so far.

Healed or quiescent temporal arteritis versus senescent changes in temporal artery biopsy specimens

Temporal arteritis (TA) is a common idiopathic vasculitis of the elderly. It is controversial whether, in the absence of an active inflammatory process, vessel damage secondary to temporal arteritis is distinguishable from changes secondary to arteriosclerosis. The primary goal of this study was to attempt to differentiate microscopically between healed temporal arteritis and arteriosclerosis, in the absence of active vasculitis. This was a retrospective study in which 47 temporal artery biopsy specimens, done between 1981 and 1997 at University of British Columbia Hospital, were reviewed. As well, temporal arteries harvested from 10 autopsy cases with no clinical evidence of vasculitis were used as controls. Haematoxylin and Eosin and Movat's pentachrome stains were used to assess the degree of intimal thickening, presence or absence of inflammation, type of inflammatory cell(s), the degree of reduplication of elastic lamina, calcification, fibrosis, neovascularisation and gaps or losses in the internal and external elastic lamina. No histological findings were specific for temporal arteritis except the presence of mural inflammation. A high degree of variability existed for all other features assessed, within all groups studied. These results indicate that, in the absence of active inflammation, structural changes in the vessel wall do not allow reliable differentiation between healed or quiescent temporal arteritis and arteriosclerosis. The common practice of performing special stains in all temporal artery biopsy cases does not contribute to the ability to recognise temporal arteritis.

Actinically degenerate elastic tissue is the likely antigenic basis of actinic granuloma of the skin and of temporal arteritis

Staining technique is paramount for detecting and assessing the severe degeneration that occurs in the elastic tissues of the skin and its arteries in response to prolonged exposure to actinic radiation. With a selective "controlled" hematoxylin-and-eosin stain, actinically damaged ("elastotic") elastic tissue stains blue, as Unna described, and contrasts with normal and simply hyperplastic elastic tissue, which stains red. "Special" elastic stains such as Orcein and Verhoeff do not demonstrate this difference. When resorptive (elastolytic) giant cell reactions develop in relation to actinically degenerate elastic tissue of the skin, the papules that arise tend to form expanding, annular rings. A previously used and appropriate name for these autoimmune lesions in the skin is actinic granuloma because this name highlights the likely actinic origin and pathogenesis of many such lesions. Granulomatous inflammation in connection with actinically degenerate internal elastic lamina appears to be the basis of temporal arteritis. Actinic granulomas may occur in the skin concurrently with temporal arteritis. A recent study of temporal arteritis strongly relates its elastic tissue changes to those of "accelerated" atherosclerosis.

Current concepts in giant cell (temporal) arteritis

Giant cell (temporal) arteritis continues to be a sight-threatening, systemic vasculitis with a poorly understood pathogenesis. The characteristic granulomatous inflammation of the vessel wall commonly leads to local ischemia. Recent advances in immunological investigations have characterized the cellular components of the disease process, but the etiology has so far remained unresolved. A reappraisal of the clinical features of giant cell (temporal) arteritis demonstrates the heterogeneity of the manifestations of the disease, including ischemic optic neuropathy. A range of new laboratory investigations and blood flow studies with color Doppler imaging have demonstrated promising roles, with respect to diagnosis and long-term follow-up. Prompt diagnosis and expeditious treatment require a high index of clinical suspicion, particularly for atypical cases. Corticosteroids remain the treatment of choice, other immuno-suppressive agents being used as second line steroid-sparing agents. Giant cell (temporal) arteritis leads to increased vascular and visual morbidity and, if untreated, may prove fatal. To maintain high standards of management of this enigmatic disorder, ophthalmologists need to be aware of the clinical spectrum of giant cell (temporal) arteritis and currently available diagnostic tests and treatment strategies.

Elastic fiber during development and aging

Elastin molecules aggregate in the extracellular space where they are crosslinked by stable desmosine bridges. The resulting polymer is structurally organized as branched fibers and lamellae, which, in skin, are wider (a few microns) in the deep dermis and become progressively thinner (fraction of a micron) towards the papillary dermis. Several general and local factors seem to regulate elastin gene expression, deposition and degradation. In skin, the volume density of the elastin network increases from birth up to maturity, when it accounts for about 3-4% of the tissue. However, its amount and distribution depend on dermis areas, which are different among subjects and change with age. Several matrix molecules (glycosaminoglycans, decorin, biglycan, osteopontin) have been found to be associated with elastin into the normal fiber, and several others have been recognized within pathologic elastic fiber (osteonectin, vitronectin, alkaline phosphatase in PXE). With age, and in some pathologic conditions, skin elastin may undergo irreversible structural and compositional changes, which seem to progress from localized deposition of osmiophilic materials to the substitution of the great majority of the amorphous elastin with interwoven filaments negative for elastin specific antibodies.

Elafin, a serine elastase inhibitor, attenuates post-cardiac transplant coronary arteriopathy and reduces myocardial necrosis in rabbits afer heterotopic cardiac transplantation

We have related experimentally induced post-cardiac transplant coronary arteriopathy to increased elastolytic activity, IL-1beta, fibronectin-mediated inflammatory and smooth muscle cell (SMC) migration, and SMC proliferation. Since our in vitro studies show that a serine elastase releases SMC mitogens and facilitates IL-lbeta induction of fibronectin, we hypothesized that administration in vivo of the specific serine elastase inhibitor, elafin, would decrease the post-cardiac transplant coronary arteriopathy. Cholesterol-fed rabbits underwent a heterotopic cardiac transplant without immunosuppression and received elafin (1.79 mg/kg per d continuous infusion after a 9 mg bolus, n = 6) or vehicle (n = 6). 1 wk later, hearts were harvested for morphometric, immunohistochemical, and biochemical analyses. A > 70% decrease in the total number of coronary arteries with intimal thickening in elafin-treated compared to control donor hearts (P < 0.002) was associated with reduced vascular elastolytic activity judged by fewer breaks in the internal elastic lamina (P < 0.03), less accumulation of immunoreactive fibronectin (P < 0.02), and reduced cell proliferation quantified by proliferating cell nuclear antigen (P < 0.0001). Despite myocardial lymphocytic infiltration, wet weight of elafin-treated donor hearts was reduced by 50% compared to untreated controls (P < 0.002) and associated with relative preservation of myocyte integrity, instead of extensive myocardial necrosis (P < 0.004). This protective effect correlated with decreased myocardial elastolytic activity (P < 0.0001) and inflammatory cell proliferation (P < 0.0001) and with an elafin-inhibitable elastase in lymphocytes. Serine elastase activity thus appears an important therapeutic target for post-cardiac transplant coronary arteriopathy and myocardial necrosis induced by rejection.

The clinical spectrum of actinic elastosis

A plethora of literature promoting our understanding of the differences between intrinsic (chronologic) aging versus extrinsic aging of the skin has been published during the last two decades. The predominant extrinsic factor is UV radiation; the functional, histologic, and clinical consequences are referred to as photoaging, or dermatoheliosis. Actinic elastosis refers specifically to the degenerative histologic alterations seen by light microscopy in sun-damaged skin. Multiple factors, including anatomic site, extent of sun exposure, and other physical or environmental factors affect the clinical appearance of these changes. We review the clinical spectrum of the actinic elastotic variants.

The endogenous vascular elastase that governs development and progression of monocrotaline-induced pulmonary hypertension in rats is a novel enzyme related to the serine proteinase adipsin

We showed previously a cause and effect relationship between increased activity of an endogenous vascular elastase (EVE) and experimentally induced pulmonary hypertension in rats. We now report the isolation and characterization of EVE. Degenerate oligonucleotides synthesized to homologous sequences in serine elastases were used in a PCR with rat pulmonary artery (PA) cDNA. The PCR product hybridized to a 1.2-kb mRNA and the intensity of hybridization was threefold increased in RNA from rat hypertensive PA at a timepoint when EVE activity was increased. The PCR product was used to screen a cDNA library and sequences obtained encoded rat adipsin. We then used immunoaffinity to purify EVE. An antibody to the elastin-binding protein was used to remove this competitor of elastase from the PA extract and the elastolytic activity increased 100-fold. The enzyme was purified using an antibody that recognizes NH2-terminal sequences of serine proteinases and the eluate was further purified using an antibody raised against recombinant adipsin. A single band at 20 kD immunoreactive with the adipsin antibody was resolved as an active enzyme on an elastin substrate gel. Immunogold labeling with an antibody to an adipsin peptide sequence localized EVE to PA smooth muscle cells. This is the first isolation of EVE; it appears to be a novel enzyme related to the serine proteinase adipsin originally found in adipose tissue.

The clinical spectrum of mid-dermal elastolysis and the role of UV light in its pathogenesis

BACKGROUND

We observed four patients with mid-dermal elastolysis (MDE) that was either precipitated or aggravated by UV light (UVL) exposure or was primarily confined to areas of UVL exposure.

OBJECTIVE

Our purpose was to report four cases of MDE occurring after significant UVL exposure and to demonstrate why we suspect that MDE in some instances may be photoinduced or photoaggravated. We also wish to demonstrate the varied clinical presentation of this disorder.

METHODS

Because all our patients had MDE involving skin exposed to UVL, biopsies were performed on clinically uninvolved sun-exposed and sun-protected skin in one patient to elucidate further the role of UVL in this process.

RESULTS

On routine histopathologic examination we found that uninvolved sun-exposed skin but not sun-protected skin demonstrated early MDE. Ultrastructural examination revealed a spectrum of elastic fiber changes in involved and clinically uninvolved sun-exposed skin. Phagocytosis of elastic fibers was not present.

CONCLUSION

We conclude that UVL exposure was a major causative or aggravating factor of MDE in our patients and that the clinical appearance of this disorder is variable.

Giant cell arteritis

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