Circulating bacterial lipopolysaccharide-induced inflammation reduces flow in brain-irrigating arteries independently from cerebrovascular prostaglandin production.

Brain dysfunction is a frequent complication of the systemic inflammatory response to bacterial infection or sepsis. In the present work, the effects of intravenous bacterial lipopolysaccharide (LPS) administration on cerebral arterial blood flow were assessed with time-of-flight (TOF)-based magnetic resonance angiography (MRA) in mice. Cerebral expression of the transcription factors nuclear factor-kappaB (NF-κB) and c-Fos and that of enzymes synthesizing vasoactive mediators, such as prostaglandins and nitric oxide, known to be increased under inflammatory conditions, were studied in the same animals. Time-resolved TOF MRA revealed no differences in blood flow in the internal carotids upstream of the circle of Willis, but indicated lower flow in its lateral parts as well as in the middle and anterior cerebral arteries after intravenous LPS injection as compared to saline administration. Although LPS did not increase c-Fos expression in ventral forebrain structures of these animals, it did induce NF-κB in meningeal blood vessels. LPS also increased cerebral expression of cyclooxygenase-2 and prostaglandin E synthase mRNAs, but de novo expression occurred in veins rather than in arteries. In conclusion, our work indicates that LPS-induced systemic inflammation does not necessarily affect filling of the circle of the Willis from the periphery, but that circulating LPS alters outflow from the circle of Willis to the middle and anterior cerebral arteries. These modifications in arterial flow were not related to increased cerebral synthesis of prostaglandins, but may instead be the consequence of the action of circulating prostaglandins and other vasoactive mediators on brain-irrigating arteries during systemic inflammation.

An acidic microenvironment increases NK cell killing of Cryptococcus neoformans and Cryptococcus gattii by enhancing perforin degranulation.

Cryptococcus gattii and Cryptococcus neoformans are encapsulated yeasts that can produce a solid tumor-like mass or cryptococcoma. Analogous to malignant tumors, the microenvironment deep within a cryptococcoma is acidic, which presents unique challenges to host defense. Analogous to malignant cells, NK cells kill Cryptococcus. Thus, as in tumor defense, NK cells must kill yeast cells across a gradient from physiologic pH to less than 6 in the center of the cryptococcoma. As acidic pH inhibits anti-tumor activities of NK cells, we sought to determine if there was a similar reduction in the anticryptococcal activity of NK cells. Surprisingly, we found that both primary human NK cells and the human NK cell line, YT, have preserved or even enhanced killing of Cryptococcus in acidic, compared to physiological, pH. Studies to explore the mechanism of enhanced killing revealed that acidic pH does not increase the effector to target ratio, binding of cytolytic cells to Cryptococcus, or the active perforin content in effector cells. By contrast, perforin degranulation was greater at acidic pH, and increased degranulation was preceded by enhanced ERK1/2 phosphorylation, which is essential for killing. Moreover, using a replication defective ras1 knockout strain of Cryptococcus increased degranulation occurred during more rapid replication of the organisms. Finally, NK cells were found intimately associated with C. gattii within the cryptococcoma of a fatal infection. These results suggest that NK cells have amplified signaling, degranulation, and greater killing at low pH and when the organisms are replicating quickly, which would help maintain microbicidal host defense despite an acidic microenvironment.

Intracerebral Mycobacterium bovis bacilli Calmette-Guerin infection-induced immune responses in the CNS.

To study whether cerebral mycobacterial infection induces granuloma and protective immunity similar to systemic infection, we intracerebrally infected mice with Mycobacterium bovis bacilli Calmette-Guerin. Granuloma and IFN-gamma(+)CD4(+) T cell responses are induced in the central nervous system (CNS) similar to periphery, but the presence of IFN-gammaIL-17 double-positive CD4(+) T cells is unique to the CNS. The major CNS source of TNF-alpha is microglia, with modest production by CD4(+) T cells and macrophage. Protective immunity is accompanied by accumulation of Foxp3(+)CD4(+) T cells and PD-L2(+) dendritic cells, suggesting that both inflammatory and anti-inflammatory responses develop in the CNS following mycobacterial infection.

Characterization of BBB permeability in a preclinical model of cryptococcal meningoencephalitis using magnetic resonance imaging.

Cryptococcus neoformans meningoencephalitis (CNME) is a leading fungal cause of death among acquired immunodeficiency syndrome patients. Innovative preclinical systems that permit high throughput in vivo evaluation of novel agents are desperately needed. Magnetic resonance imaging (MRI) was evaluated as a tool to develop a rat model of CNME and to quantify noninvasively blood-brain barrier (BBB) disruption secondary to this disease. The aim of this study was to identify MRI changes compared with histopathology and fungal burden measurements as potential biomarkers. A well-characterized strain of C neoformans (CN) var grubii was used to infect rats using intravenous inoculation. An inoculum-finding study was performed by infecting rats with 10(3), 10(5), and 10(7) colony-forming units (CFUs). Animals underwent dynamic MRI on days 4 and 7 after inoculation. An inoculum-confirming study was performed by infecting rats with 10(5), 10(6), and 10(7) CFU and fungal burden was determined in the brain, lung, and spleen. Animals infected with 10(7) CFU of CN developed lesions that appeared hyperintense on T2-weighted images on day 4. The histopathology results correlated well with MRI data. Diffusion weighted and permeability estimates were 1.4 and 6.1-fold higher, respectively, in lesions compared with healthy tissue. Magnetic resonance imaging is a promising preclinical tool to evaluate effects of antifungal and adjunctive agents.

Mycotic encephalitis and nephritis in a dog due to infection with Cladosporium cladosporioides.

The dematiaceous fungus Cladosporium cladosporioides is a widely distributed saprophyte that is reported to occasionally infect the lung, skin, eye and brain of humans. This report describes a German shepherd dog with granulomatous encephalitis and nephritis due to C. cladosporioides infection. Although the fungal organisms appeared non-pigmented in haematoxylin and eosin stained sections, they were readily identified with histochemical stains. Semi-nested polymerase chain reaction using universal fungal primers amplified fungal DNA from fixed tissue that had identity to that of C. cladosporioides on sequencing.

A novel cerebral microangiopathy with endothelial cell atypia and multifocal white matter lesions: a direct mycoplasmal infection?

We present 3 sporadic cases of a subacute to chronic, progressive motor (i.e. weakness, ataxia, spasticity, dysarthria, and dysphagia) and cognitive disorder in adults of both sexes, without proven immunocompromise or malignancy. Neuroimaging studies revealed tiny calcifications with atrophy of the cerebrum, pons, and midbrain in 1 patient, cerebral atrophy in another, and cerebral atrophy and periventricular white matter hyperintensities in the third. Clinical diagnoses included cortico-pontine-cerebellar degeneration, mixed neurodegenerative disorder, progressive supranuclear palsy, diffuse Lewy body disease, and Lyme disease. One atrophic brain revealed widely disseminated, millimeter-sized gray lesions in cerebral white matter and obscured anatomic markings of the basis pontis. The most conspicuous microscopic feature in all was capillaries with focally piled up endothelial nuclei, some of which appeared to be multinucleated, or enlarged, hyperchromatic crescentic single nuclei. Although seen mostly without associated damage, they were also noted with white matter lesions displaying vacuolation, demyelination, spheroids, necrosis, vascular fibrosis, and mineralization; these were most severe in the basis pontis. Immunostains and probes to herpes simplex virus-I, -II, and -8; adenovirus, cytomegalovirus, varicella-zoster, Epstein-Barr virus, measles, JC virus, and herpes hominis virus-6 were negative. Electron microscopy revealed no virions in endothelial cells with multilobed or multiple nuclei and duplicated basal laminae. However, mycoplasma-like bodies, mostly 400 to 600 nm in size, were found in endothelial cell cytoplasm and capillary lumina. Platelets adhered to affected endothelial cells. Polymerase chain reaction and immunohistochemistry of fixed samples for Mycoplasma fermentans were negative; other species of Mycoplasma remain viable pathogenic candidates.

Gene and protein expression of galectin-3 and galectin-9 in experimental pneumococcal meningitis.

Inflammation of the subarachnoid and ventricular space contributes to the development of brain damage i.e. cortical necrosis and hippocampal apoptosis in pneumococcal meningitis (PM). Galectin-3 and -9 are known pro-inflammatory mediators and regulators of apoptosis. Here, the gene and protein expression profile for both galectins was assessed in the disease progression of PM. The mRNA of Lgals3 and Lgals9 increased continuously in the cortex and in the hippocampus from 22 h to 44 h after infection. At 44 h after infection, mRNA levels of Lgals9 in the hippocampus were 7-fold and those of Lgals3 were 30-fold higher than in uninfected controls (P<0.01). Galectin-9 protein did not change, but galectin-3 significantly increased in cortex and hippocampus with the duration of PM. Galectin-3 was localized to polymorphonuclear neutrophils, microglia, monocytes and macrophages, suggesting an involvement of galectin-3 in the neuroinflammatory processes leading to brain damage in PM.

Prevention of brain injury by the nonbacteriolytic antibiotic daptomycin in experimental pneumococcal meningitis.

Bacteriolytic antibiotics cause the release of bacterial components that augment the host inflammatory response, which in turn contributes to the pathophysiology of brain injury in bacterial meningitis. In the present study, antibiotic therapy with nonbacteriolytic daptomycin was compared with that of bacteriolytic ceftriaxone in experimental pneumococcal meningitis, and the treatments were evaluated for their effects on inflammation and brain injury. Eleven-day-old rats were injected intracisternally with 1.3 x 10(4) +/- 0.5 x 10(4) CFU of Streptococcus pneumoniae serotype 3 and randomized to therapy with ceftriaxone (100 mg/kg of body weight subcutaneously [s.c.]; n = 55) or daptomycin (50 mg/kg s.c.; n = 56) starting at 18 h after infection. The cerebrospinal fluid (CSF) was assessed for bacterial counts, matrix metalloproteinase-9 levels, and tumor necrosis factor alpha levels at different time intervals after infection. Cortical brain damage was evaluated at 40 h after infection. Daptomycin cleared the bacteria more efficiently from the CSF than ceftriaxone within 2 h after the initiation of therapy (log(10) 3.6 +/- 1.0 and log(10) 6.3 +/- 1.4 CFU/ml, respectively; P < 0.02); reduced the inflammatory host reaction, as assessed by the matrix metalloproteinase-9 concentration in CSF 40 h after infection (P < 0.005); and prevented the development of cortical injury (cortical injury present in 0/30 and 7/28 animals, respectively; P < 0.004). Compared to ceftriaxone, daptomycin cleared the bacteria from the CSF more rapidly and caused less CSF inflammation. This combined effect provides an explanation for the observation that daptomycin prevented the development of cortical brain injury in experimental pneumococcal meningitis. Further research is needed to investigate whether nonbacteriolytic antibiotic therapy with daptomycin represents an advantageous alternative over current bacteriolytic antibiotic therapies for the treatment of pneumococcal meningitis.

Aspergillus galactomannan antigen in the cerebrospinal fluid of bone marrow transplant recipients with probable cerebral aspergillosis.

The Aspergillus galactomannan test was performed on cerebrospinal fluid and serum samples from 5 patients with probable cerebral aspergillosis and from 16 control patients. Cerebrospinal fluid galactomannan levels were significantly higher in aspergillosis patients, and most galactomannan was produced intrathecally. Comparison of serum galactomannan values in pulmonary and cerebral aspergillosis patients showed significant overlapping. Detection of Aspergillus galactomannan in cerebrospinal fluid may be diagnostic of cerebral aspergillosis.

Cerebral nocardiosis characterized by magnetic resonance spectroscopy in vivo.

We describe a patient with multiple cerebral lesions that initially were believed to be tumor metastases but were later found to be caused by Nocardia asteroides, after magnetic resonance spectroscopy (MRS) findings suggested that the lesions were infective in origin. This case report demonstrates the ability of MRS, a noninvasive imaging modality, to aid in the diagnosis of brain infection.

Pseudomonas fluorescens as a potential pathogen: adherence to nerve cells.

In order to determine the infectious potential of the psychrotrophic bacterium Pseudomonas fluorescens, a species closely related to the opportunistic pathogen P. aeruginosa, we investigated the binding activity of this bacterium on primary cultures of rat neonate cortical neurons and glial cells, adrenal paraneurons and NG108-15 neuroblastoma cells. Incubated at concentrations of 10(6) and 10(8) CFU/mL, P. fluorescens MF37 exhibited a high binding activity on neurons in the same range as that of P. aeruginosa PAO1. A significant, but lower, adherence of P. fluorescens was also detected on glial cells and adrenal paraneurons. In contrast, when P. fluorescens MF37 or P. aeruginosa PAO1 were incubated with neuroblastoma cells, no binding was observed. In neurons, the association of P. fluorescens with the plasma membrane occurred both on neurites and cell body. Leakage of the cytoplasmic content was frequently noted. Studies performed using the fluorescent probe Hoechst 33258 revealed that in 10% of neurons, P. fluorescens induced the appearance of densely stained clusters of DNA that was typical of an early step of apoptosis. In glial cells exposed to P. fluorescens, marked changes in the morphology of the nucleus, including fragmentation into lobular structures and aggregation of DNA, were also reminiscent of the existence of a possible apoptotic mechanism. Taken together, these results reveal that P. fluorescens can bind to nerve cells and affect their physiology and, in agreement with recent clinical observations, suggest that P. fluorescens could behave as a pathogen.

Cerebral vasculitis in chronic mucocutaneous candidiasis: autopsy case report.

An autopsy case of chronic mucocutaneous candidiasis (CMCC) is reported here, in which cerebral vasculitis developed in the final stage. A 32-year-old man who had suffered from superficial candidial infection since his childhood was diagnosed as having CMCC. During the past 7 years the patient had developed various associated disorders including insulin-dependent diabetes mellitus (IDDM), common variable immunodeficiency (CVID), candidial esophagitis, multiple digestive tract ulcers and pyothorax. In 1998, at the age of 32, he developed convulsions that were accompanied by impairment of consciousness, and which were temporarily treated with steroid pulsed-medication. Epileptic status associated with widespread cerebral infarctions occurred subsequently, however, and the patient died of sepsis 2 months later. At autopsy, multiple cerebral infarctions and arterial thrombosis were evident. These were histologically proven to be primary vasculitis which was confined solely to the brain, and this was verified by general pathological examination. Thus, some as yet unknown cerebrovascular factors might be involved in the onset of an autoimmune-related vasculitis in patients with a longstanding immunodeficiency state such as CMCC.

Successful treatment of cerebral aspergillosis with a high oral dose of itraconazole after excisional surgery.

We report a case of cerebral aspergillosis which originated from the sphenoid sinus, and involved a progressive decrease of visual acuity. The neurological signs indicated a cavernous sinus invasion. After extensive intracranial surgery we treated the residual aspergillosis with a high oral dose of itraconazole (800 mg/d for 4 months, followed by 400 mg/d for 5 months). The neurological impairments of the patient gradually subsided with the resolution of the fungal lesion shown on MRI. The successful therapy indicated that itraconazole has a significant role in the treatment of advanced cerebral aspergillosis if it is used in high doses (16 mg/kg/d for adults).

Alzheimer's disease may not be a spirochetosis.

It has been reported previously that spirochetes could be one of the causes of Alzheimer's disease (AD). In this study, we have attempted to reproduce these findings by examining fresh blood samples from 22 patients diagnosed with early stage (n = 16) and late stage (n = 6) AD. The patients were participants in a clinical drug trial. Fresh necropsy brain cortical specimens from AD patients (n = 7) were also examined. Spirochetes were observed microscopically in the blood of only one late-stage AD patient. None of the brain tissues showed the presence of spirochetes. Our results suggest that spirochetes are probably not associated with AD.

Cerebral vasculitis associated with chronic mucocutaneous candidiasis.

Chronic mucocutaneous candidiasis is a heterogenous group of disorders, associated with a variety of autoimmune disorders and a broad spectrum of immune aberrations. We describe 2 patients with chronic mucocutaneous candidiasis who had cerebrovascular disease with severe neurologic sequelae. Results of angiography of cerebral vessels and brain biopsy in one were consistent with the diagnosis of cerebral vasculitis.

[Treatment review in rhinocerebral mucormycosis]. / Revisión del tratamiento en la mucormicosis rinocerebral.

The rhinocerebral mucormycosis is the more common form produced by Rhizopus, a genus of fungi. It's a serious infective disease with high mortality, that needs a precocious medical treatment. Amphotericin B is the choice medical treatment, but liposomal amphotericine B in recent years is a better drug, due to minor renal toxicity and greater tisular diffusion. Even can not to treat all affected areas it's necessary an extensive surgical treatment according to individual characteristics and disease evolution. A 56-year-old man with rhinocerebral mucormycosis, caused by Rhizopus, who was treated with liposomal-amphotericin B and extensive rhino-orbital surgery is presented.

[Rhino-orbital-cerebral mucormycosis. Review, update and report of a new case]. / La mucormicosis rino-órbito-cerebral. Revisión, actualización y aportación de un nuevo caso.

Mucormycosis is a fungal infection that often is fatal. It usually affects diabetic or immunocompromised patients. The site of onset generally is the nasal mucosa and the disease extends rapidly to the palate, orbit and brain. Early diagnosis is important and is based on the clinical features (diabetes, black eschar in nose, palate or face) and demonstration of the characteristic hyphae in the biopsy of the nasal mucosa or oral lesions. Treatment is based on systemic antifungal therapy, radical surgery, and medical management of the underlying disease. A case of rhino-orbital-cerebral mucormycosis is presented and the world literature is reviewed.

Propionibacterium acnes in the cortex of patients with Alzheimer's disease.

Propionibacterium acnes was found in the cortex of three patients with Alzheimer's disease and in one frontal cortex of an elderly patient with cardiovascular risk factors and hypoxia due to a large glioblastoma of the right frontal lobe with severely increased intracranial pressure. Propionibacterium acnes is an atypical anaerobic bacterium which is sensitive to cephalosporins, but insensitive to metronidazole. It is concluded that a capillary microangiopathy (in consequence of old age and cardiovascular risk factors such as high blood pressure) leads to cortical hypoxia and reduced resistance of the cortical immune system. Prevention by dietary regimes counteracting microangiopathy and treatment with cephalosporins are recommended.