Human plasmacytoid dendritic cells sense lymphocytic choriomeningitis virus-infected cells in vitro.

We previously reported that exosomal transfer of hepatitis C virus (HCV) positive-strand RNA from human Huh-7 hepatoma cells to human plasmacytoid dendritic cells (pDCs) triggers pDC alpha/beta interferon (IFN-α/ß) production in a Toll-like receptor 7 (TLR7)-dependent, virus-independent manner. Here we show that human pDCs are also activated by a TLR7-dependent, virus-independent, exosomal RNA transfer mechanism by human and mouse hepatoma and nonhepatoma cells that replicate the negative-strand lymphocytic choriomeningitis virus (LCMV).

Arenavirus diversity and evolution: quasispecies in vivo.

Arenaviruses exist as viral quasispecies due to the high mutation rates of the low-fidelity viral RNA-dependent RNA polymerase (RdRp). This genomic heterogeneity is advantageous to the population, allowing for adaptation to rapidly changing environments that present varying types and degrees of selective pressure. The significant variation in biological properties observed among lymphocytic choriomeningitis virus (LCMV) strains, the prototypic arenavirus, indicates to what extent a quasis-pecies dynamics may play a role in arenavirus adaptability and pathogenesis. Several aspects of arenavirus variability and its contribution to pathogenesis will be discussed.

Exploring ischemia-induced vascular lesions and potential pharmacological intervention strategies.

Structural changes in vessels under the influence of ischemia play an important role in the pathogenesis of many diseases, most important of which are stroke and myocardial infarction or myocardial insult. Over the years, information has been gathered, which implicate a role for ischemic vascular changes in the pathogenesis of crush-syndrome, atherosclerosis and other vascular diseases. When blood vessels are damaged they become unresponsive to a stimulus, which normally elicits vasodilatation and can lead to intraluminal thrombosis and ischemic events. The aim of this review is to explore the structural changes seen in vessels affected by ischemia reperfusion injury. With ischemia, the development of observable changes to vascular structure is multifactorial. One key factor is reperfusion ischemic injury. Moreover, the duration of the ischemic event is an important factor when determining both the prognosis and the type of morphological change that is observable in affected vessel walls. In this regard, the deleterious progression of blood flow impairment and its severity depends on the specific organ involved and the type of tissue affected. Further, there are regional differences within affected tissues and the degree of microvascular injury is well correlated with differences in the nature and severity of the ischemic event. Any method aimed at preventing and treating ischemic reperfusion injuries in vessels, based on these investigations, should likewise be able to decrease the early signs of brain, cerebrovascular and heart injury and preserve normal cellular architecture.

Hippocampal nitric oxide upregulation precedes memory loss and A beta 1-40 accumulation after chronic brain hypoperfusion in rats.

Chronic brain hypoperfusion (CBH) using permanent occlusion of both common carotid arteries in an aging rat model, has been shown to mimic human mild cognitive impairment (MCI), an acknowledged high risk condition that often converts to Alzheimer's disease. An aging rat model was used to determine whether hippocampal nitric oxide (NO) is abnormally expressed following CBH for two or eight weeks. At each time point, spatial memory was measured with the Morris water maze and hippocampal A beta 1-40/1-42 concentrations were obtained using sandwich ELISA. Real-time amperometric measures of NO representing the constitutive isoforms of neuronal nitric oxide synthase (nNOS) and endothelial (e)NOS were also taken at each time point to ascertain whether NO levels changed as a result of CBH, and if so, whether such NO changes preceded or followed any memory or amyloid-beta pathology. We found that two weeks after CBH, NO hippocampal levels were upregulated nearly four-fold when compared to nonoccluded rats but no alteration in spatial memory of A beta products were observed at this time point. By contrast, NO concentration had declined to control levels by eight weeks but spatial memory was found significantly impaired and A beta 1-40 (but not A beta 1-42) had increased in the CBH group when compared to control rats. Since changes in shear stress are known to upregulate eNOS but generally not nNOS, these results suggest that shear stress induced by CBH hyperactivated vascular NO derived from eNOS in the first two weeks as a reaction by the capillary endothelium to maintain homeostasis of local cerebral blood flow. The return of vascular NO to basal levels after eight weeks of CBH may have triggered metabolic changes within hippocampal cells resulting in hippocampal dysfunction as reflected by spatial memory impairment and by accumulation of A beta 1-40 peptide. In conclusion, our study shows that CBH initiates spatial memory loss in aging rats thus mimicking human MCI and also increases A beta 1-40 in the hippocampus. The memory and amyloid changes are preceded by NO upregulation in the hippocampus. These preliminary findings may be important in understanding, at least in part, the molecular mechanisms that precede memory impairment during chronic brain ischemia and as such, the pre-clinical stage leading to Alzheimer's disease.

Vascular basis of Alzheimer's pathogenesis.

Considerable evidence now indicates that Alzheimer's disease (AD) is primarily a vascular disorder. This conclusion is supported by the following evidence: (1) epidemiologic studies linking vascular risk factors to cerebrovascular pathology that can set in motion metabolic, neurodegenerative, and cognitive changes in Alzheimer brains; (2) evidence that AD and vascular dementia (VaD) share many similar risk factors; (3) evidence that pharmacotherapy that improves cerebrovascular insufficiency also improves AD symptoms; (4) evidence that preclinical detection of potential AD is possible from direct or indirect regional cerebral perfusion measurements; (5) evidence of overlapping clinical symptoms in AD and VaD; (6) evidence of parallel cerebrovascular and neurodegenerative pathology in AD and VaD; (7) evidence that cerebral hypoperfusion can trigger hypometabolic, cognitive, and degenerative changes; and (8) evidence that AD clinical symptoms arise from cerebromicrovascular pathology. The collective data presented in this review strongly indicate that the present classification of AD is incorrect and should be changed to that of a vascular disorder. Such a change in classification would accelerate the development of better treatment targets, patient management, diagnosis, and prevention of this disorder by focusing on the root of the problem. In addition, a theoretical capsule summary is presented detailing how AD may develop from chronic cerebral hypoperfusion and the role of critically attained threshold of cerebral hypoperfusion (CATCH) and of vascular nitric oxide derived from endothelial nitric oxide synthase in triggering the cataclysmic cerebromicrovascular pathology.

Alzheimer disease as a vascular disorder: nosological evidence.

BACKGROUND: The main stumbling block in the clinical management and in the search for a cure of Alzheimer disease (AD) is that the cause of this disorder has remained uncertain until now. SUMMARY OF REVIEW: Evidence that sporadic (nongenetic) AD is primarily a vascular rather than a neurodegenerative disorder is reviewed. This conclusion is based on the following evidence: (1) epidemiological studies showing that practically all risk factors for AD reported thus far have a vascular component that reduces cerebral perfusion; (2) risk factor association between AD and vascular dementia (VaD); (3) improvement of cerebral perfusion obtained from most pharmacotherapy used to reduce the symptoms or progression of AD; (4) detection of regional cerebral hypoperfusion with the use of neuroimaging techniques to preclinically identify AD candidates; (5) presence of regional brain microvascular abnormalities before cognitive and neurodegenerative changes; (6) common overlap of clinical AD and VaD cognitive symptoms; (7) similarity of cerebrovascular lesions present in most AD and VaD patients; (8) presence of cerebral hypoperfusion preceding hypometabolism, cognitive decline, and neurodegeneration in AD; and (9) confirmation of the heterogeneous and multifactorial nature of AD, likely resulting from the diverse presence of vascular risk factors or indicators of vascular disease. CONCLUSIONS: Since the value of scientific evidence generally revolves around probability and chance, it is concluded that the data presented here pose a powerful argument in support of the proposal that AD should be classified as a vascular disorder. According to elementary statistics, the probability or chance that all these findings are due to an indirect pathological effect or to coincidental circumstances related to the disease process of AD seems highly unlikely. The collective data presented in this review strongly support the concept that sporadic AD is a vascular disorder. It is recommended that current clinical management of patients, treatment targets, research designs, and disease prevention efforts need to be critically reassessed and placed in perspective in light of these important findings.

Clinically asymptomatic axial disease in psoriatic spondyloarthropathy. A retrospective study.

The aim of this study was to analyse retrospectively the prevalence and the clinical features of clinically asymptomatic axial involvement in patients with psoriasis and axial radiological features of spondyloarthropathy (PsSpA). We performed a cross-sectional study based on the clinical records of 70 patients, 44 men and 26 women, with a mean age of 48.7+/-14.2 years. PsSpA was defined by the presence of radiographic sacroiliitis (SI) greater than or equal to grade 2, and/or any other typical radiological sign of spondylitis in patients with psoriasis. When the radiological signs were present in the absence of inflammatory back pain and/or buttock pain, patients were grouped as having asymptomatic axial disease. HLA-B27 was determined by serological methods in the 70 patients and in 82 healthy controls from our general population. Fourteen patients (20%), 11 with radiological SI, two with facet joint erosion-fusion and one with aseptic discitis, showed no evidence of symptomatic spinal disease. Twenty-nine patients (41%) showed cervical spine disease (CSD), but only 17 of them (58.6%) had pain and rigidity at this level, whereas 12 (41.4%) did not show clinical symptoms. CSD was associated with duration of arthritis (P = 0.043) and peripheral erosions (P = 0.037). HLA-B27 correlated well with bilateral SI (P = 0.002) and PsSpA (P<0.0004, RR 6.4), but showed no association with unilateral SI nor with syndesmophytes or asymptomatic disease. Univariate analysis demonstrated associations between symptomatic disease and longer duration of arthritis (P = 0.041) and higher IgM values (P = 0.05). There is a high prevalence of asymptomatic involvement in patients with PsSpA The significance of these asymptomatic changes is not known, but they probably represent a common characteristic of spondyloarthropathies rather than a specific feature associated with psoriasis.

Alzheimer's disease: how does it start?

Presently, non-genetic Alzheimer's disease (AD) is wrongly classified as a neurodegenerative disorder. When vascular lesions are present, AD is considered to be a vascular dementia. However, compelling evidence indicates that (AD) is a vascular disorder with neurodegenerative consequences. There is an urgent clinical need to ascertain the true cause of this dementia. In this review, evidence indicating that AD is a vascular disorder comes from a number of different disciplines including studies in epidemiology, pharmacology, neuroimaging, clinical medicine, pathology, physiology and experimental research. This collective evidence also addresses many previously puzzling questions regarding: i) past and present treatment failures in AD, ii) strange association of AD risk factors with many vascular-related disorders, iii) parallel lesions, clinical symptoms risk factors and potentially interchangeable treatments present in AD and vascular dementia, iv) historical difficulty in finding neurodegenerative markers to detect AD pre-clinically, and, v) paradoxical pathophysiologic events preceding AD neurodegenerative changes. Re-classifying AD as a vascular disorder would very likely improve the chances of finding a useful treatment for this disorder because clinical study designs could focus on more realistic and relevant pathologic targets than is presently practiced. A short summary of potential new research lines that may provide novel therapy in the treatment and management of AD is discussed.

Comparative analysis of psoriatic spondyloarthropathy between men and women.

This study analyzed gender-related differences in a cohort of patients with psoriatic spondyloarthropathy (SpA) We performed a retrospective cross-sectional study of 100 patients (mean age 48 +/- 14 years; 63 men, 37 women), diagnosed as having psoriatic SpA on the basis of ESSG criteria. All patients were studied according to a standard protocol, and HLA-B27 and Cw status were analyzed in the study population and their frequencies compared to that of 177 healthy blood donors. The clinical features of PsSpA were compared between men and women by univariate analyses. Twenty-three patients showed isolated axial disease (M:F ratio 3.6:1), 36 had polyaxial disease (M:F ratio 1:1), and 41 showed oligoaxial pattern (M:F ratio 1.7:1). HLA-B27 was correlated with male sex (P=0.002) and isolated axial disease (P=0.016). Univariate analysis showed female sex to be correlated with lower complement levels (P < 0.05), erosive disease (P = 0.05), higher swelling joint count (P = 0.002), and higher scores on the Health Assessment Questionnaire-Specific for SpA (P < 0.05). The HLA-B27 antigen seems to be a defined genetic risk factor only in men with psoriatic SpA. The extent of the spondylitic process is quite similar between the two, although women show poorer functional performance and more aggressive peripheral disease.

RING finger Z protein of lymphocytic choriomeningitis virus (LCMV) inhibits transcription and RNA replication of an LCMV S-segment minigenome.

Arenaviruses have a bisegmented negative-strand RNA genome whose proteomic capability is limited to only four polypeptides, namely, nucleoprotein (NP), surface glycoprotein (GP) that is proteolytically processed into GP1+GP2, polymerase (L), and a small (11-kDa) RING finger protein (Z). The role of Z during the Lymphocytic choriomeningitis virus (LCMV) life cycle is poorly understood. We investigated the function of Z in virus transcription and replication by using a reverse genetic system for the prototypic arenavirus LCMV. This system involves an LCMV minigenome and the minimal viral trans-acting factors (NP and L), expressed from separated cotransfected plasmids. Cotransfection of the Z cDNA strongly inhibited LCMV minigenome expression. The effect required synthesis of Z protein; its magnitude was dose dependent and occurred with levels of Z protein substantially lower than those observed in LCMV-infected cells. Coexpression of Z did not prevent the encapsidation of plasmid supplied minigenome, but it affected both transcription and RNA replication similarly. Mutations in Z that unfolded its RING finger domain eliminated its inhibitory activity, but RING proteins not related to Z did not affect LCMV minigenome expression. Consistent with the minigenome results, cells transiently expressing Z exhibited decreased susceptibility to infection with LCMV.

N-terminal domain of Borna disease virus G (p56) protein is sufficient for virus receptor recognition and cell entry.

Borna disease virus (BDV) surface glycoprotein (GP) (p56) has a predicted molecular mass of 56 kDa. Due to extensive posttranslational glycosylation the protein migrates as a polypeptide of 84 kDa (gp84). The processing of gp84 by the cellular protease furin generates gp43, which corresponds to the C-terminal part of gp84. Both gp84 and gp43 have been implicated in viral entry involving receptor-mediated endocytosis and pH-dependent fusion. We have investigated the domains of BDV p56 involved in virus entry. For this, we used a pseudotype approach based on a recently developed recombinant vesicular stomatitis virus (VSV) in which the gene for green fluorescent protein was substituted for the VSV G protein gene (VSV Delta G*). Complementation of VSV Delta G* with BDV p56 resulted in infectious VSV Delta G* pseudotypes that contained both BDV gp84 and gp43. BDV-VSV chimeric GPs that contained the N-terminal 244 amino acids of BDV p56 and amino acids 421 to 511 of VSV G protein were efficiently incorporated into VSV Delta G* particles, and the resulting pseudotype virions were neutralized by BDV-specific antiserum. These findings indicate that the N-terminal part of BDV p56 is sufficient for receptor recognition and virus entry.