Hirano body in an inflammatory cell of leptomeningeal vessel infected by fungus Paecilomyces

Cerebral vasculitis caused by Talaromyces marneffei and Aspergillus niger in a HIV-positive patient: a case report and literature review

Cerebral vasculitis is a long-standing but flourishing and fadeless research topic. Infections are a frequent cause of cerebral vasculitis, vital to diagnose due to involvement of specific anti-infection treatments. A 65-year-old man visited the hospital for his neurological symptoms without obvious inducements. After admission, radiological examination and comprehensive conventional microbiological tests (CMTs) revealed suspected intracranial infectious vasculitis. Metagenomic next-generation sequencing (mNGS) and reverse transcription-polymerase chain reaction further confirmed that his cerebral vasculitis was caused by Talaromyces marneffei (T. marneffei) and Aspergillus niger (A. niger) co-infection. The patient’s final diagnosis changed from initial herpetic encephalitis, due to the past history of cephalosome and facial herpes and non-significant antiviral therapeutic effects, to fungal cerebral vasculitis. The patient was discharged after use of targeted antifungal therapies on day 18 of his admission, and his associated symptoms disappeared completely at follow-up 3 weeks later. We first illustrated the presence of uncommon cerebral vasculitis caused by T. marneffei and A. niger in a human immunodeficiency virus-positive patient. In clinically suspected patients with infectious cerebral vasculitis, mNGS should be performed to detect potential pathogens if CMTs may not provide useful pathogenic clues, highlighting the importance of mNGS in the diagnosis and treatment of infectious diseases.

C1q, the classical complement pathway protein binds Hirano bodies in Pick's disease

Haematoxylin/Eosin staining was performed to screen for Hirano bodies from the temporal lobe including the hippocampus in 10 Pick's disease cases containing Pick bodies. Although the inclusions were confirmed in 9 out of 10 cases, only 4 out of 10 were particularly enriched with the eosinophilic bodies. These were subjected to immunostaining with anticomplement antibodies and astrocyte marker antiglial fibrillary acidic protein antibody and the HLA class II CR3/43 antibody to visualize microglia. An intraneuronal Hirano body was observed in one case that otherwise contained mainly the extracellular inclusions. In all cases, the extracellular Hirano bodies were seen lying adjacent to soma of neurons within CA1 region of the hippocampus. The extracellular Hirano bodies stained intensely with C1q, the first component of the classical pathway of activation but remained unreactive against antibodies to C4 and the C3 activation products (C3b and iC3b) and the alternative complement pathway component factor B. Hirano bodies also remained negative with the antiglial fibrillary acidic protein for astrocytes and HLA class II antibody CR3/43 for microglia. The results demonstrate that Hirano bodies have strong immunoreactivity to C1q; however, whether other complement components are associated with these inclusions remains to be further investigated.

Actin and Diseases of the Nervous System

Abnormal regulation of the actin cytoskeleton results in several pathological conditions affecting primarily the nervous system. Those of genetic origin arise during development, but others manifest later in life. Actin regulation is also affected profoundly by environmental factors that can have sustained consequences for the nervous system. Those consequences follow from the fact that the actin cytoskeleton is essential for a multitude of cell biological functions ranging from neuronal migration in cortical development and dendritic spine formation to NMDA receptor activity in learning and alcoholism. Improper regulation of actin, causing aggregation, can contribute to the neurodegeneration of amyloidopathies, such as Down's syndrome and Alzheimer's disease. Much progress has been made in understanding the molecular basis of these diseases.

The presence of FAC1 protein in Hirano bodies

We have previously reported that the FAC1 protein is contained in hippocampal structures that resemble Hirano bodies. Hirano bodies are cytoplasmic inclusions containing actin filaments that are numerous in the hippocampus of many Alzheimer's disease patients. FAC1 is a developmentally regulated protein that is localized to the cytoplasm of neurons during development and is predominately a nuclear protein in adult brain. In hippocampal sections from non-demented adults. Alzheimer's disease, and dementia with Lewy bodies patients. Hirano bodies were immunolabelled with antibodies to the FAC1 protein. Confocal laser microscopy demonstrated the presence of actin in FAC1 labelled Hirano bodies, and ultrastructural analysis confirmed the presence of a lattice structure within FAC1 labelled Hirano bodies. Numerous FAC1 immunoreactive swollen dendrites were also present in the hippocampus of Alzheimer's disease and dementia with Lewy bodies patients. Within any one case the total number of FAC1 positive swollen dendrites correlated with the total number of Hirano bodies, suggesting an association between the two structures. Thus, FAC1 protein is contained in Hirano bodies and swollen dendrites in the hippocampus of patients with Alzheimer's disease and dementia with Lewy bodies.

Hirano bodies and chronic alcoholism

Experiments on rodents have shown convincingly that chronic ethanol ingestion may damage the hippocampal formation. Nevertheless this region has, hitherto, not been considered as a target for alcoholism-induced brain lesions in man. Guided by the observation of increased numbers of Hirano bodies (HB) in the hippocampus of chronic alcoholics, this study determines the maximum number of HB per high power field (HPF: 0.19 mm2) in the stratum pyramidale (HBpyr) and in the stratum lacunosum (HBlac) of Ammon's horn in 123 chronic alcoholics and in 197 controls. The average count of HBlac found in alcoholics was 14.4 (SD = 17.7) compared with 4.2 (SD = 7.4) in non-alcoholics (P < 0.001). Counts of more than 19 HBlac per HPF were revealed as highly indicative of chronic alcoholism being observed in 33 (27%) alcoholics and in six (3%) non-alcoholics (P < 0.001). An increased number of HBlac was the most frequent of the neuropathological findings in the alcoholics. Affirming observations of others, the count of HBlac peaked during middle age and declined thereafter. The maximum count of HBpyr, in contrast, increased with age and was independent of alcoholism. It is proposed that increased numbers of HBlac indicate alterations of the apical dendrites of the pyramidal neurons of the CA1 field of Ammon's horn which probably are due to direct neurotoxic effects of ethanol and which may be reversible in nature.

Hirano bodies and related neuronal inclusions

Hirano bodies are bright eosinophilic intracytoplasmic inclusions which have a highly characteristic crystalloid fine structure. They occur preferentially in the neuronal processes of the CA1 area in Ammon's horn in a wide variety of conditions, especially amyotrophic lateral sclerosis and parkinsonism-dementia complex on Guam, Alzheimer's disease, Pick's disease and 'normal' elderly individuals. Hirano bodies contain epitopes of actin, actin-associated proteins, tau, middle molecular weight neurofilaments subunit and a C-terminal fragment of beta-amyloid precursor protein. In addition to the CA1 area of Ammon's horn, they have also been identified in many other areas of the nervous system in humans and various experimental animals. Although usually observed in neurons, Hirano bodies may also be present in other cell types. It is the consensus that Hirano bodies in the pyramidal layer of CA1 originate largely from an age-related alteration of the microfilamentous system.

Crystalloid bodies in skeletal muscle of hypothyroid myopathy. Ultrastructural and histochemical studies

Crystalloid bodies in skeletal muscle fibers have been described in myopathic and non-myopathic conditions. They have been interpreted as viral, glycogen, protein-glycogen complex, artifacts and of unknown nature. This report described similar crystalloid bodies in the postmortem muscle samples of two patients with hypothyroid myopathy. The crystalloid bodies were preferentially located in the I band and Z line region and in the subsarcolemmal region closely associated with lipofuscin. Some were present within basophilic bodies. They were formed by parallel filaments of 6-10 nm beaded periodically by electron-dense particles of 10-18 nm in a lattice, hexagonal or parallel-ripple pattern. Merging of filaments of crystalloid bodies into actin filaments of the I band was noted. The electron-dense particles stained strongly with periodic acid-thiocarbohydrazide-silver proteinate method for polysaccharides and were unaffected or partially digested by diastase treatment on the ultrathin sections. The filamentous component was neither stained for polysaccharides nor digested by diastase treatment. It is suggested that crystalloid bodies of muscle fibers are composed of two distinct subunits with particles of glycogen complex attached to filaments of unknown nature.

Cerebral Paecilomyces javanicus infection. An ultrastructural study

A 41-year-old diabetic woman developed Paecilomyces javanicus endocarditis and subsequent cerebral fungal embolism and vasculitis with massive infarction and hemorrhage 6 years after a mitral valve replacement with porcine heterograft. The organism was identified by the culture from the infected brain tissue and aortic valve. Cerebral infection due to fungus Paecilomyces is rare. This report documents the cerebral manifestations of fungus Paecilomyces javanicus and describes for the first time the ultrastructure of such an organism obtained from the infected tissue. Their ultrastructural findings, similar to those described in Paecilomyces farinosus derived from culture, include a double-layered cell wall, a triple unit plasma membrane, abundant cytoplasmic lipid droplets, vacuoles, membranous profiles and septal formation. This report further demonstrates hyphae with packed 50A filaments and granulofibrillary material and features suggestive of intrahyphal hyphae, not previously described in fungus Paecilomyces.