Experimental influenza causes a non-permissive viral infection of brain, liver and muscle

Viral entry and translation in brain endothelia provoke influenza-associated encephalopathy

Influenza-associated encephalopathy (IAE) is extremely acute in onset, with high lethality and morbidity within a few days, while the direct pathogenesis by influenza virus in this acute phase in the brain is largely unknown. Here we show that influenza virus enters into the cerebral endothelium and thereby induces IAE. Three-weeks-old young mice were inoculated with influenza A virus (IAV). Physical and neurological scores were recorded and temporal-spatial analyses of histopathology and viral studies were performed up to 72 h post inoculation. Histopathological examinations were also performed using IAE human autopsy brains. Viral infection, proliferation and pathogenesis were analyzed in cell lines of endothelium and astrocyte. The effects of anti-influenza viral drugs were tested in the cell lines and animal models. Upon intravenous inoculation of IAV in mice, the mice developed encephalopathy with brain edema and pathological lesions represented by micro bleeding and injured astrocytic process (clasmatodendrosis) within 72 h. Histologically, massive deposits of viral nucleoprotein were observed as early as 24 h post infection in the brain endothelial cells of mouse models and the IAE patients. IAV inoculated endothelial cell lines showed deposition of viral proteins and provoked cell death, while IAV scarcely amplified. Inhibition of viral transcription and translation suppressed the endothelial cell death and the lethality of mouse models. These data suggest that the onset of encephalopathy should be induced by cerebral endothelial infection with IAV. Thus, IAV entry into the endothelium, and transcription and/or translation of viral RNA, but not viral proliferation, should be the key pathogenesis of IAE.

Aging augments the impact of influenza respiratory tract infection on mobility impairments, muscle-localized inflammation, and muscle atrophy

Although the influenza virus only infects the respiratory system, myalgias are commonly experienced during infection. In addition to a greater risk of hospitalization and death, older adults are more likely to develop disability following influenza infection; however, this relationship is understudied. We hypothesized that upon challenge with influenza, aging would be associated with functional impairments, as well as upregulation of skeletal muscle inflammatory and atrophy genes. Infected young and aged mice demonstrated decreased mobility and altered gait kinetics. These declines were more prominent in hind limbs and in aged mice. Skeletal muscle expression of genes involved in inflammation, as well as muscle atrophy and proteolysis, increased during influenza infection with an elevated and prolonged peak in aged mice. Infection also decreased expression of positive regulators of muscle mass and myogenesis components to a greater degree in aged mice. Gene expression correlated to influenza-induced body mass loss, although evidence did not support direct muscle infection. Overall, influenza leads to mobility impairments with induction of inflammatory and muscle degradation genes and downregulation of positive regulators of muscle. These effects are augmented and prolonged with aging, providing a molecular link between influenza infection, decreased resilience and increased risk of disability in the elderly.

The liver is a metabolic and immunologic organ: A reconsideration of metabolic decompensation due to infection in inborn errors of metabolism (IEM)

Metabolic decompensation in inborn errors of metabolism (IEM) is characterized by a rapid deterioration in metabolic status leading to life-threatening biochemical perturbations (e.g. hypoglycemia, hyperammonemia, acidosis, organ failure). Infection is the major cause of metabolic decompensation in patients with IEM. We hypothesized that activation of the immune system during infection leads to further perturbations in end-organ metabolism resulting in increased morbidity. To address this, we established model systems of metabolic decompensation due to infection. Using these systems, we have described the pathologic mechanisms of metabolic decompensation as well as changes in hepatic metabolic reserve associated with infection. First and foremost, our studies have demonstrated that the liver experiences a significant local innate immune response during influenza infection that modulates hepatic metabolism. Based on these findings, we are the first to suggest that the role of the liver as a metabolic and immunologic organ is central in the pathophysiology of metabolic decompensation due to infection in IEM. The dual function of the liver as a major metabolic regulator and a lymphoid organ responsible for immunosurveillance places this organ at risk for hepatotoxicity. Mobilization of hepatic reserve and the regenerative capacity of a healthy liver compensates for this calculated risk. However, activation of the hepatic innate immune system may be deleterious in IEM. Based on this assertion, strategies aimed at modulating the innate immune response may be a viable target for intervention in the treatment of hepatic metabolic decompensation.

Influenza Virus-Associated Fatal Acute Necrotizing Encephalopathy: Role of Nonpermissive Viral Infection?

In 2014, two unusual peaks of H1N1 influenza outbreak occurred in Nakhon Ratchasima Province, in Thailand. Among 2,406 cases, one of the 22 deaths in the province included a 6-year-old boy, who initially presented with acute necrotizing encephalopathy. On the other hand, his sibling was mildly affected by the same influenza virus strain, confirmed by whole-genome sequencing, with one silent mutation. Absence of acute necrotizing encephalopathy and other neurological illnesses in the family and the whole province, with near identical whole viral genomic sequences from the two siblings, and an absence of concomitant severe lung infection (cytokine storm) at onset suggest nonpermissive infection as an alternative pathogenetic mechanism of influenza virus.

Neurologic manifestations and complications of pandemic influenza A H1N1 in Malaysian children: what have we learnt from the ordeal?

INTRODUCTION

In 2009, pandemic influenza A H1N1 emerged in Mexico and subsequently spread worldwide. In Malaysia, there were more than a thousand of confirmed cases among children. The general clinical characteristics of these children have been well-published. However, the description of neurologic complications is scarce.

OBJECTIVE

This study aims to describe the characteristics of neurologic manifestations and complications in a national paediatric cohort with pandemic influenza A H1N1.

METHODS

During the pandemic, children (12 years or less) admitted for novel influenza A H1N1 in 68 Malaysian public hospitals, were prospectively enrolled into national database. The clinical, laboratory and neuro-imaging data for children with neurologic manifestations, hospitalized from 15th June 2009 till 30th November 2009, was reviewed.

RESULTS

Of 1244 children with influenza A H1N1 during the study period, 103 (8.3%) presented with influenza-related neurological manifestations. The mean age of our study cohort was 4.2 years (SD: 3.3 years). Sixty percent of them were males. Sixty-nine (66.9%) were diagnosed as febrile seizures, 16 (15.5%) as breakthrough seizures with underlying epilepsy, 14 (13.6%) as influenza-associated encephalopathy or encephalitis (IAE) and 4 (3.9%) as acute necrotizing encephalopathy of childhood (ANEC). All 4 available CSF specimens were negative for influenza viral PCR. Among 14 children with brain-imaging done, 9 were abnormal (2: cerebral oedema, 4: ANEC and 3: other findings). There were four deaths and three cases with permanent neurological sequelae.

CONCLUSION

About one-tenth of children with pandemic influenza A H1N1 presented with neurologic complications. The most common diagnosis was febrile seizures. One-fifth of those children with neurologic presentation had IAE or ANEC, which carried higher mortality and morbidity. This large national study provides us useful data to better manage children with neurologic complications in the future pandemic influenza outbreaks.

Neurologic aspects of influenza viruses

Although influenza A and B viruses are primarily known as respiratory viruses and mainly infected only the upper respiratory tract in humans, patients with influenza often develop signs and symptoms that are not due to the respiratory system. Frequently individuals with influenza develop headaches, meningismus, and even seizures in addition to their typical respiratory symptoms. In the past decades, influenza viruses have also been associated with serious non-respiratory signs. The famous 1918 strain of influenza was associated with von Economo's encephalitis lethargica and postencephalitic parkinsonism. In the 1960s influenza virus infections in children were associated with Reye's syndrome characterized often by fatty non-inflammatory hepatic disease and an encephalopathy with marked non-inflammatory cerebral edema. Intermittently children with influenza develop focal myalgia and myositis. Guillain–Barré syndrome was epidemiologically associated with the 1978 killed influenza vaccine but not subsequent vaccines. Although occasional children with influenza have developed encephalopathy, from 2000 through 2004 there was an increase in the number of serious cases of acute necrotizing encephalopathy accompanying infection with the influenza A 2009 strain. The current H5N1 strain of bird influenza occasionally infects humans with a high mortality rate and some appear to have central nervous signs. This chapter explores what is known about these influenza neurologic associations.

Productive infection of human skeletal muscle cells by pandemic and seasonal influenza A(H1N1) viruses

Besides the classical respiratory and systemic symptoms, unusual complications of influenza A infection in humans involve the skeletal muscles. Numerous cases of acute myopathy and/or rhabdomyolysis have been reported, particularly following the outbreak of pandemic influenza A(H1N1) in 2009. The pathogenesis of these influenza-associated myopathies (IAM) remains unkown, although the direct infection of muscle cells is suspected. Here, we studied the susceptibility of cultured human primary muscle cells to a 2009 pandemic and a 2008 seasonal influenza A(H1N1) isolate. Using cells from different donors, we found that differentiated muscle cells (i. e. myotubes) were highly susceptible to infection by both influenza A(H1N1) isolates, whereas undifferentiated cells (i. e. myoblasts) were partially resistant. The receptors for influenza viruses, α2-6 and α2-3 linked sialic acids, were detected on the surface of myotubes and myoblasts. Time line of viral nucleoprotein (NP) expression and nuclear export showed that the first steps of the viral replication cycle could take place in muscle cells. Infected myotubes and myoblasts exhibited budding virions and nuclear inclusions as observed by transmission electron microscopy and correlative light and electron microscopy. Myotubes, but not myoblasts, yielded infectious virus progeny that could further infect naive muscle cells after proteolytic treatment. Infection led to a cytopathic effect with the lysis of muscle cells, as characterized by the release of lactate dehydrogenase. The secretion of proinflammatory cytokines by muscle cells was not affected following infection. Our results are compatible with the hypothesis of a direct muscle infection causing rhabdomyolysis in IAM patients.

Role of Fat-Soluble Vitamins A and D in the Pathogenesis of Influenza: A New Perspective

Reduced exposure to solar radiation, leading to a deficiency of vitamin D and hence impaired innate immunity, has been suggested as a trigger for influenza viral replication and as an explanation of seasonal influenza. Although this hypothesis accounts for many unexplained facts about the epidemiology of influenza, gaps remain in understanding the pathogenesis and manifestations of the disease. Several observations suggest a role for vitamin A compounds (retinoids) in the disease. This paper presents a new model of the etiopathogenesis of influenza, suggesting that host resistance and susceptibility depend importantly on the ratio of vitamin D to vitamin A activity. Retinoid concentrations within normal physiological limits appear to inhibit influenza pathogenesis whereas higher background concentrations (i.e., very low vitamin D : A ratios) increase the risk of severe complications of the disease. There is also evidence that influenza-induced or preexisting liver disease, diabetes, and obesity worsen the severity of infection, possibly via liver dysfunction and alterations in retinoid metabolism. The model could be tested by determining the presence of retinoids in the secretions of patients with influenza and by studies of retinoid profiles in patients and controls. Potential strategies for prevention and treatment are discussed.

Evidence of viremia in 2 cases of severe pandemic influenza A H1N1/09

The recent pandemic of the 2009 pandemic influenza A (H1N1) infrequently caused severe disease. We describe 2 cases of 2009 H1N1 influenza with rapid progression resulting in respiratory failure and need for prolonged intensive care support. Real-time polymerase chain reaction amplification for influenza A (using a Centers for Disease Control and Prevention protocol) and the 2009 H1N1 influenza (using an in-house protocol) was performed on serial respiratory and serum specimens from both patients collected over 3 weeks. Both patients repeatedly demonstrated 2009 H1N1 influenza in respiratory specimens. Evidence of influenza A viremia was also detected in both cases, although it was confirmed as 2009 H1N1 influenza in only one. The presence of viremia in cases of severe 2009 H1N1 influenza has potential prognostic and therapeutic implications. Detection of viremia may be useful as a predictive marker for severe disease. Antiviral agents with low serum levels may be ineffective if administered to patients with influenza viremia.

Influenza virus infection in multinucleated skeletal myofibers

We examined the progression of the WSN influenza virus infection in isolated, multinucleated rat skeletal myofibers. Contrary to mononucleated cells, the adsorbed virions showed markedly delayed entry kinetics. Viral budding occurred on the sarcolemma, but the hemagglutinin envelope glycoprotein matured inefficiently and was poorly cleaved. Compatible with this, plaque assays indicated that infective viral particles were not formed. In situ hybridization studies showed that at low-dose infection, viral RNA production was restricted to one or a few nuclei within a myofiber. Dual in situ hybridization indicated that two different viral RNAs usually co-localized in the same nucleus or nuclei, suggesting that different viral genome segments replicated in the same nucleus. Newly synthesized viral ribonucleoprotein particles (vRNPs) did not re-enter virgin nuclei. Therefore, a single infected nucleus was able to support viral protein production, and notably, these proteins could reach hundreds of micrometers from the nucleus of origin. These results suggest that after viral disassembly in the endosome, the genome segments remained glued together and entered a myonucleus as a package. Spreading of the infection into virgin nuclei either by vRNPs or newly made virions did not occur, and thus the infection was abortive.

Effect of influenza vaccination on oxidative stress products in breath

Viral infections cause increased oxidative stress, so a breath test for oxidative stress biomarkers (alkanes and alkane derivatives) might provide a new tool for early diagnosis. We studied 33 normal healthy human subjects receiving scheduled treatment with live attenuated influenza vaccine (LAIV). Each subject was his or her own control, since they were studied on day 0 prior to vaccination, and then on days 2, 7 and 14 following vaccination. Breath volatile organic compounds (VOCs) were collected with a breath collection apparatus, then analyzed by automated thermal desorption with gas chromatography and mass spectroscopy. A Monte Carlo simulation technique identified non-random VOC biomarkers of infection based on their C-statistic values (area under curve of receiver operating characteristic). Treatment with LAIV was followed by non-random changes in the abundance of breath VOCs. 2, 8-Dimethyl-undecane and other alkane derivatives were observed on all days. Conservative multivariate models identified vaccinated subjects on day 2 (C-statistic = 0.82, sensitivity = 63.6% and specificity = 88.5%); day 7 (C-statistic = 0.94, sensitivity = 88.5% and specificity = 92.3%); and day 14 (C-statistic = 0.95, sensitivity = 92.3% and specificity = 92.3%). The altered breath VOCs were not detected in live attenuated influenza vaccine, excluding artifactual contamination. LAIV vaccination in healthy humans elicited a prompt and sustained increase in breath biomarkers of oxidative stress. A breath test for these VOCs could potentially identify humans who are acutely infected with influenza, but who have not yet developed clinical symptoms or signs of disease.

Posterior reversible encephalopathy syndrome and cerebral vasculopathy associated with influenza A infection: report of a case and review of the literature

BACKGROUND AND PURPOSE

Influenza A infection can precipitate encephalopathy, encephalitis, or Reye syndrome with the development of cerebral edema in children and is associated with an increased incidence of stroke in adults. The mechanism of these events is poorly understood. Posterior reversible encephalopathy syndrome (PRES) is seen in association with infection/sepsis, and cerebral vasculopathy has been demonstrated in PRES. We describe a case of PRES that develops in association with influenza A.

SUMMARY OF CASE

A normotensive 65-year-old woman presented with altered mentation and nausea in the setting of a viral prodromal illness ultimately confirmed as influenza A. Posterior reversible encephalopathy syndrome developed on the second day after admission. Catheter cerebral angiogram documented vasculopathy in PRES-involved regions with areas of focal vessel dilatation and string-of-bead appearance.

CONCLUSIONS

The association between influenza A and PRES with documentation of cerebral vasculopathy suggests a common systemic vascular mechanism behind PRES and influenza-related encephalopathic edema and stroke.

Influenza A encephalopathy, cerebral vasculopathy, and posterior reversible encephalopathy syndrome: combined occurrence in a 3-year-old child

Encephalopathy is an uncommon complication of childhood influenza infection, typically recognized during influenza epidemics. Imaging hallmarks include characteristic thalamic lesions, thalamic necrosis and hemispheric edema. We describe a child with acute influenza A associated necrotizing encephalopathy with MR angiographic evidence of significant cerebral vasculopathy and a hemispheric edema pattern consistent with PRES. This case reinforces that significant cerebral vasculopathy can accompany influenza infection and that influenza is a likely trigger for PRES.

Impaired long-chain fatty acid metabolism in mitochondria causes brain vascular invasion by a non-neurotropic epidemic influenza A virus in the newborn/suckling period: implications for influenza-associated encephalopathy

The neuropathogenesis of influenza-associated encephalopathy in children and Reye's syndrome remains unclear. A surveillance effort conducted during 2000-2003 in South-West Japan reveals that almost all fatal and handicapped influenza-associated encephalopathy patients exhibit a disorder of mitochondrial beta-oxidation with elevated serum acylcarnitine ratios (C(16:0)+C(18:1))/C(2). Here we show invasion by a non-neurotropic epidemic influenza A H3N2 virus in cerebral capillaries with progressive brain edema after intranasal infection of mice having impaired mitochondrial beta-oxidation congenitally or posteriorly in the newborn/ suckling periods. Mice genetically lacking of carnitine transporter OCTN2, resulting in carnitine deficiency and impaired beta-oxidation, exhibited significant higher virus-genome numbers in the brain, accumulation of virus antigen exclusively in the cerebral capillaries and increased brain vascular permeability compared to in wild type mice. Mini-plasmin, which proteolytically potentiates influenza virus multiplication in vivo and destroys the blood-brain barrier, accumulated with virus antigen in the brain capillaries of OCTN2-deficient mice but only a little in wild-type mice. These results suggest that the impaired mitochondrial beta-oxidation changes the susceptibility to a non-neurotropic influenza A virus as to multiplication in the brain capillaries and to cause brain edema. These pathological findings in the brain of mice having impaired mitochondrial beta-oxidation after influenza virus infection may have implications for human influenza-associated encephalopathy.

Identification of trypsin I as a candidate for influenza A virus and Sendai virus envelope glycoprotein processing protease in rat brain

Extracellular cleavage of virus envelope fusion glycoprotein hemagglutinin (HA0) by host trypsin-like proteases is a prerequisite for the infectivity and pathogenicity of human influenza A viruses and Sendai virus. The common epidemic influenza A viruses are pneumotropic, but occasionally cause encephalopathy or encephalitis, although the HA0 processing enzyme in the brain has not been identified. In searching for the brain processing proteases, we identified a processing enzyme in rat brain that was inducible by infection with these viruses. The purified enzyme exhibited an apparent molecular mass of approximately 22 kDa on SDS-PAGE and the N-terminal amino acid sequence was consistent with that of rat pancreatic trypsin I. Its substrate specificities and inhibition profiles were the same as those of pancreatic trypsin I. In situ hybridization and immunohistochemical studies on trypsin I distribution revealed heavy deposits in the brain capillaries, particularly in the allocortex, as well as in clustered neuronal cells of the hippocampus. The purified enzyme efficiently processed the HA0 of human influenza A virus and the fusion glycoprotein precursor of Sendai virus. Our results suggest that trypsin I in the brain potentiates virus multiplication in the pathogenesis and progression of influenza-associated encephalopathy or encephalitis.

Influenza virus and CNS manifestations

Neurological involvement during influenza infection has been described during epidemics and is often consistent with serious sequelae or death. An increasing incidence of influenza-associated encephalitis/encephalopathy has been reported in Japan, mainly in children. A variety of other clinical CNS manifestations, such as Reye's syndrome, acute necrotising encephalopathy (ANE), and myelitis as well as autoimmune conditions, such as Guillain-Barre's syndrome, may occur during the course of influenza infection. Virological diagnosis is essential and based on virus isolation, antigen detection, RNA detection by PCR, and serological analyses. Neuroimaging with CT and MRI of the brain are of prognostic value. The pathogenic mechanisms behind the influenza CNS complications are unknown. The treatment is symptomatic, with control of vital functions in the intensive care unit, antiepileptic medication and treatment against brain oedema.

Accumulation of mini-plasmin in the cerebral capillaries causes vascular invasion of the murine brain by a pneumotropic influenza A virus: implications for influenza-associated encephalopathy

The infectivity and pathogenicity of influenza virus are primarily determined by host cellular trypsin-type processing proteases which cleave the viral membrane fusion glycoprotein hemagglutinin (HA). Therefore the distribution of the processing protease is a major determinant of the infectious organ tropism. The common epidemic human influenza A virus is pneumotropic and the HA processing proteases tryptase Clara, mini-plasmin, tryptase TC30 and ectopic anionic trypsin have all been isolated from mammalian airways. However, the pneumotropic influenza virus occasionally causes severe brain edema, particularly in children presenting with Reye's syndrome treated with aspirin, or in children with influenza-associated encephalopathy without antipyretic treatment. We have observed that, after influenza virus infection, the accumulation of mini-plasmin in the cerebral capillaries in mice with a congenital or acquired abnormality of mitochondrial beta-oxidation mimicking the pathological findings of Reye's syndrome, causes an invasion and multiplication of the pneumotropic influenza virus at these same locations. From these findings, we hypothesize that the accumulated mini-plasmin modifies the brain capillaries from a non-permissive to a permissive state, thereby allowing multiplication of pneumotropic influenza virus. In addition, mini-plasmin proteolytically destroys the blood-brain barrier. These pathologic findings, consistent with encephalopathy in mice with a systemic impairment of beta-oxidation, may have implications for human influenza encephalopathy.

Experimental models of pulmonary infection

Experimental models of pulmonary infection are being discussed, focused on various aspects of good experimental design, such as choice of animal species and infecting strain, and route of infection/inoculation techniques (intranasal inoculation, aerosol inoculation, and direct instillation into the lower respiratory tract). In addition, parameters to monitor pulmonary infection are being reviewed such as general clinical signs, pulmonary-associated signs, complication of the pulmonary infection, mortality rate, and parameters after dissection of animals. Examples of pulmonary infection models caused by bacteria, fungi, viruses or parasites in experimental animals with intact or impaired host defense mechanisms are shortly summarized including key-references.

Neurocognitive performance and quality of life in patients with HIV infection

We examined the relationship of HIV-related cognitive impairment and health-related quality of life (QoL). Subjects were administered measures of cognitive function (a battery of 17 neuropsychological tests) and of QoL (the MOS-HIV questionnaire). Study measures also included comprehensive clinical and neurological evaluation, laboratory testing, and brain imaging studies in patients with impaired neuropsychological evaluation. One-hundred and eleven subjects were examined. Cognitively impaired patients (33.3%) reported poorer QoL scores in all domains (p < 0.05): physical health summary score (PHS) (44.6 vs. 49.9), mental health summary score (MHS) (37.7 vs. 44.4), pain (67.6 vs. 79.4), physical functioning (75.9 vs. 87.7), role functioning (32.4 vs. 41.5), social functioning (70.3 vs. 83.5), mental health (48.2 vs. 61.0), energy (53.1 vs. 63.0), health distress (60.8 vs. 75.5), cognitive functioning (CF) (60.5 vs. 71.8), general health perceptions (29.2 vs. 43.4), and QoL (36.5 vs. 47.0). The number of altered neuropsychological tests correlated significantly with MHS (p < 0.001), PHS (p < 0.03), CF (p < 0.02), and QoL (p < 0.02) scores. A correlation between seven of seven neuropsychological measures exploring speed of mental processing, three of four exploring mental flexibility, four of six exploring memory, and two of two exploring fine motor functioning and MHS, PHS, CF, or QoL scores was also found. Poor performance on the Digit Symbol test was most strongly associated with poor MHS (OR 1.04, 95% CI 1.01-1.08, p < 0.009) and PHS (OR 1.04, 95% CI 1.01-1.08, p < 0.01) scores, controlling for CD4 count, previous AIDS diagnosis, receiving HAART, and drug abuse. Cognitive impairment is associated with poor QoL. People with more severe cognitive impairment have the highest probability of having a poor QoL. Cognitive impairment in any cognitive domain explored in our battery is also associated with poor QoL. Poor performance on the Digit Symbol Test is the strongest predictor of poor QoL.

Lack of detection of influenza genes in archived formalin-fixed, paraffin wax-embedded brain samples of encephalitis lethargica patients from 1916 to 1920

A method was developed for detection of influenza genes in formalin-fixed brains of mice that had been experimentally infected with influenza A/NWS/33 (H1N1) virus. Using this technique, messenger ribonucleic acid (mRNA) of the beta-actin gene was detected in eight clinical brain samples from the 1916-1920 outbreak of encephalitis lethargica, showing preservation of particular mRNAs. However, we did not detect influenza nucleotide sequences of M, NP, and NS genes from these same samples. We conclude either that influenza was not the causative agent of encephalitis lethargica or, possibly, that the virus had a hit-and-run mechanism and was no longer present in the brain at the time of death of the patients.

Influenza infection exerts prominent inflammatory and thrombotic effects on the atherosclerotic plaques of apolipoprotein E-deficient mice

BACKGROUND

The role of infection in the development and complications of atherosclerosis has been the focus of much attention. We reported previously that influenza vaccination was associated with reduced risk of recurrent myocardial infarction. Here, we report the effect of influenza A virus on the apolipoprotein E-deficient (apoE(-/-)) mouse, an animal model of atherosclerosis.

METHODS AND RESULTS

Twenty-four apoE(-/-) mice >24 months old were injected with 1 LD(50) (lethal dose 50) of influenza A virus. Ten wild-type C57BL/6 infected mice and 11 noninfected age-matched apoE(-/-) mice served as controls. Multiple aortic sections were studied histologically 3, 5, and 10 days later. The infected mice showed markedly increased intimal cellularity compared with the noninfected apoE(-/-) mice. No aortic abnormalities were seen in infected wild-type mice. Ten infected apoE(-/-) mice had a significant subendothelial infiltrate composed of a heterogeneous group of cells that stained positively for smooth muscle cell actin, F4/80 (macrophages), and CD3 (T lymphocytes). One case of subocclusive platelet and fibrin-rich thrombus was seen.

CONCLUSIONS

This study shows that influenza infection promotes inflammation, smooth muscle cell proliferation, and fibrin deposition in atherosclerotic plaques.

Changes in neurocognitive performance in a cohort of patients treated with HAART for 3 years

OBJECTIVES

To describe changes in HIV-associated neurocognitive impairment in patients treated with highly active antiretroviral therapy (HAART) for at least 3 years.

METHODS

Prospective, observational study of comprehensive neuropsychologic (NP) testing, neurologic examination, and laboratory measures before HAART and after 6, 15 and 45 months of HAART, on 28 consecutive patients seen in our department since April 1996.

RESULTS

At baseline, 16 patients were neurocognitively impaired and 12 were not. Among the 16 impaired patients, 5 patients failed to meet the criteria for impairment after 6 months and 9 patients after both 15 and 45 months of HAART, respectively. Statistically significant improvements ( p < or =.01) were seen in two of six measures exploring the concentration and speed of mental processing, two of three measures exploring mental flexibility, in one of five measures exploring memory, and in two of two measures exploring fine motor functions. Unimpaired study subjects performed better than impaired ones in 10 of 17 measures at baseline, in eight of 17 after 6 months, in six of 17 after 15 months, and in seven of 17 after 45 months of HAART.

CONCLUSIONS

During the course of HAART, patients experienced a positive and sustained improvement in their neurocognitive performance. However, the presence of 7 of 16 (43.7%) patients with neurocognitive impairment, and the persistence of statistically significant differences in the neurocognitive performance between impaired and unimpaired patients after more than 3 years of HAART, suggests that ongoing HIV-related neurologic damage can occur even during potent antiretroviral treatment.