A current view of mitochondria damage and the diversity of lipopigment inclusions in neuronal ceroid lipofuscinose type 2 from rectal biopsy.

Neuronal ceroid lipofuscinoses (NCLs) are a growing group of neurodegenerative storage diseases, in which specific features are sought to facilitate the creation of a universal diagnostic algorithm in the future. In our ultrastructural studies, the group of NCLs was represented by the CLN2 disease caused by a defect in the TPP1 gene encoding the enzyme tripeptidyl-peptidase 1. A 3.5-year-old girl was affected by this disease. Due to diagnostic difficulties, the spectrum of clinical, enzymatic, and genetic tests was extended to include analysis of the ultrastructure of cells from a rectal biopsy. The aim of our research was to search for pathognomonic features of CLN2 and to analyse the mitochondrial damage accompanying the disease. In the examined cells of the rectal mucosa, as expected, filamentous deposits of the curvilinear profile (CVP) type were found, which dominated quantitatively. Mixed deposits of the CVP/fingerprint profile (FPP) type were observed less frequently in the examined cells. A form of inclusions of unknown origin, not described so far in CLN2 disease, were wads of osmophilic material (WOMs). They occurred alone or co-formed mixed deposits. In addition, atypically damaged mitochondria were observed in muscularis mucosae. Their deformed cristae had contact with inclusions that looked like CVPs. Considering the confirmed role of the c subunit of the mitochondrial ATP synthase in the formation of filamentous lipopigment deposits in the group of NCLs, we suggest the possible significance of other mitochondrial proteins, such as mitochondrial contact site and cristae organizing system (MICOS), in the formation of these deposits. The presence of WOMs in the context of searching for ultrastructural pathognomonic features in CLN2 disease also requires further research.

TDP-43 pathology in subacute sclerosing panencephalitis.

Subacute sclerosing panencephalitis (SSPE) is a fatal, slowly progressive brain disorder caused by a mutated measles virus. Both subacute inflammatory and neurodegenerative mechanisms appear to play significant roles in the pathogenesis. TAR DNA-binding protein 43 (TDP-43) inclusions are a common co-pathology in several neurodegenerative disorders with diverse pathogenesis. In the present study, we examined brains of 16 autopsied SSPE patients for the presence of TDP-43 pathology and possible associations with tau pathology. Immunohistochemical staining identified TDP-43 inclusions in 31% of SSPE cases. TDP-43 pathology was widely distributed in the brains, most severely in the atrophied cerebral cortex (temporal and parietal), and most frequently as tangle- and thread-like neuronal cytoplasmic inclusions. It was associated with longer disease duration (>4 years) and tau pathology (all TDP-43-positive cases had tau-positive neurofibrillary tangles). This study demonstrates for the first time an association between TDP-43 pathology and SSPE. The co-occurrence of TDP-43 and tau aggregates and correlation with the disease duration suggest that both pathological proteins are involved in the neurodegenerative process induced by viral inflammation.

Damage to the orbicularis oculi muscle may impair the development of dermatochalasis.

The purpose of this article is to investigate the changes that occur in the orbicularis oculi muscle (OOM) in patients with dermatochalasis. The OOM specimens from 26 patients were collected during upper eyelid blepharoplasty. Each specimen was divided into three parts, which were then examined using different techniques: formalin embedding for light microscopy, free freezing for histochemical examination, and fixation in 3% glutaraldehyde for electron microscopy. The severity of dermatochalasis was classified according to the anatomical landmarks. 78 specimens from patients with dermatochalasis were evaluated. Under light microscopy, specimens showed an increase in muscle fiber size variation, rounding of muscle fibers, and lobulation of myocytes in a fibrotic background. Under electron microscopy, loss of myofilaments, vacuolar vesicles, and swollen mitochondria were observed, along with osmophilic aggregates resembling nemadine bodies and collagen fibrils. A statistically significant association between the progression of dermatochalasis and the presence of aggregates resembling nemaline bodies was found (p- value < 0.005). Significant changes occur in the OOM in patients with dermatochalasis and the presence of aggregates resembling nemaline bodies is correlated with the degree of eyelid drooping. Thus, OOM may contribute in dermatochalasis progression.

Incidence and morphology of secondary TDP-43 proteinopathies: Part 2.

Transactivation (TAR) DNA binding protein 43 kDa (TDP-43) inclusions frequently occur as a comorbid pathology in several neurodegenerative disorders, including Alzheimer's disease, Huntington's disease, Lewy body disease, and progressive supranuclear palsy, and may appear in association with nondegenerative neurological etiology, for example neoplastic, paraneoplastic, traumatic, or infectious. Relationships between various pathological proteins and mechanisms associated with TDP-43-induced neurodegeneration are still not fully understood. Thus, overlap of distinct neuropathological mechanisms frequently leads to greater brain atrophy and a more severe clinical course, suggesting the importance of co-pathologies in ante-mortem diagnosing and treatment. The present review aims to discuss the incidence, morphology, and role of TDP-43 pathology in the context of other dominant, hallmark pathologies, referred to as secondary TDP-43 proteinopathies. The previous part (Part 1) focused on common neurodegenerative diseases, including Alzheimer's disease, Huntington's disease, and Lewy body disease, while the present part (Part 2) discusses TDP-43 pathology in rare neurodegenerative diseases and neurological diseases with nondegenerative etiology.

Influence of SARS-CoV-2 on Adult Human Neurogenesis.

Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is associated with the onset of neurological and psychiatric symptoms during and after the acute phase of illness. Inflammation and hypoxia induced by SARS-CoV-2 affect brain regions essential for fine motor function, learning, memory, and emotional responses. The mechanisms of these central nervous system symptoms remain largely unknown. While looking for the causes of neurological deficits, we conducted a study on how SARS-CoV-2 affects neurogenesis. In this study, we compared a control group with a group of patients diagnosed with COVID-19. Analysis of the expression of neurogenesis markers showed a decrease in the density of neuronal progenitor cells and newborn neurons in the SARS-CoV-2 group. Analysis of COVID-19 patients revealed increased microglial activation compared with the control group. The unfavorable effect of the inflammatory process in the brain associated with COVID-19 disease increases the concentration of cytokines that negatively affect adult human neurogenesis.

Incidence and morphology of secondary TDP-43 proteinopathies: Part 1.

Transactive response DNA binding protein of 43 kDa (TDP-43) is considered to play an essential role in the pathogenesis of frontotemporal lobar degeneration and amyotrophic lateral sclerosis. Growing body of evidence indicate that pathological TDP-43 inclusions frequently occur in the context of other distinctive hallmark pathologies, referred to as secondary TDP-43 proteinopathies. Comorbid TDP-43 pathology is well-documented in several neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, multiple system atrophy, or progressive supranuclear palsy. It may also appear as a consequence of less obvious disease etiologies, i.e. post-traumatic (chronic traumatic encephalopathy), neoplastic (pilocytic astrocytoma), or post-infectious (post-encephalitic parkinsonism). The aim of the present review was to evaluate the incidence, morphology, and role of TDP-43 pathology in the secondary TDP-43 proteinopathies. This article (Part 1) discussed TDP-43 pathology in more common neurodegenerative diseases, including Alzheimer's disease, Lewy body disease, Huntington's disease, multiple system atrophy, corticobasal degeneration, and progressive supranuclear palsy. A follow-up article (Part 2) will describe abnormal TDP-43 changes in rare neurodegenerative diseases or neurological diseases with nondegenerative etiology.

Neuropathological analysis of the brains of fifty-two patients with COVID-19.

Coronavirus disease 2019 (COVID-19) poses a global challenge to healthcare and society in the early 21st century. We report neuropathological changes in 52 patients aged between 22 years and 88 years (median 58 years) who were infected with the CoV-2 coronavirus. Patients died under various circumstances and had various pre-existing diseases. The inclusion criteria for this study were: positive result for the nasopharyngeal swab for SARS-CoV-2 RNA, diagnosis of pneumonia of SARS-CoV-2 or nucleoproteins of SARS-CoV-2 in pulmonary tissue confirmed by immunohistochemical methods (IHC). Samples from all brain structures and lung specimens were taken for histopathological examinations. Brain and pulmonary samples were stained typically with histological and immunohistochemical methods and small tissue fragments were examined with the transmission electron microscope (TEM). The light and electron microscopy examination confirmed the numerous neuropathological changes in the brains of the patients infected with the CoV-2. Many of these changes were caused by pre-existing diseases of patients and/or by necessary treatment. However, vascular lesions and the inflammatory process seem to be characteristic of the CoV-2 infection. In all of the structures of 52 brains of patients, damage of the vessel walls and morphological feature of the damage to the blood-brain barrier were observed. Lymphocytic and microglial infiltrates, both perivascular and diffuse, were also observed. Hence, the brain changes due to COVID-19 infection, could be called COVID-19 cerebral angiopathy with diffuse inflammation.

Ultrastructure of mitochondria and damage to small blood vessels in siblings with the same mutation in the NOTCH 3 and coexisting diseases.

We performed ultrastructural studies of mitochondria and evaluated the appearance of small blood vessels of three middle-aged siblings affected by the same mutation in the NOTCH3 gene, causing CADASIL. CADASIL pathognomonic features include granular osmiophilic material (GOM), which we observed. GOMs were located in damaged and thickened basement membranes (BM) of capillaries and arterioles. Our patients were also burdened by type II diabetes (first patient), impaired glucose metabolism (second patient), and hypertension (third patient). The ultrastructure of the capillaries in the first and second patients differed from the third patient. In diabetes/impaired glucose metabolism patients (first and second patients), we observed: pathologies of mitochondria in damaged endothelium and pericytes of capillaries; extremely thickened (BM) with visible remains of vascular cells; well-preserved GOMs anchored in the rebuilt capillary extracellular matrix. We identified degenerated or vestigial small blood vessels of skeletal muscles in the first patient. The capillary damage in the third patient (with hypertension) was milder compared to the diabetes/impaired glucose metabolism patients. We conclude that in patients with a mutation in the NOTCH3 gene, the co-occurrence of diseases such as type II diabetes/impaired glucose metabolism can cause a multiplication the damages to small blood vessels by modifying/masking the pathogenesis of CADASIL.

Encephalomyelitis associated with rheumatoid arthritis: a case report.

Encephalitis/encephalomyelitis in the course of rheumatoid arthritis (RA) remains a matter of debate. We present a case of a patient with encephalomyelitis associated with RA confirmed with post-mortem neuropathological examination. A 68-year-old woman with a long-standing, seropositive history of RA presented progressive disturbances of consciousness. Magnetic resonance imaging (MRI) of the brain and cervical spine revealed an increase of signal intensity on T2-weighted and fluid attenuated inversion recovery (FLAIR) images with corresponding restricted diffusion involving cerebral peduncles, pons, medulla oblongata, and cervical spinal cord and mild contrast-enhancement of the right cerebral peduncle. Extensive radiological and laboratory testing, including autoantibodies to paraneoplastic anti-neuronal and neuronal cell surface antigens, were all negative except for elevated rheumatoid factor. Cerebrospinal fluid (CSF) analysis revealed moderate pleocytosis with mononuclear cell predominance, mildly increased protein level, and negative viral PCRs, bacterial cultures, flow cytometry, and neuronal surface antibodies. Despite intensive treatment with corticosteroids, antibiotics, antiviral drugs, and intravenous immunoglobulin the patient died after 3 months of hospitalization. Post-mortem neuropathological examination revealed numerous, disseminated, heterochronous ischaemic lesions, rarely with haemorrhagic transformation, predominantly in the brainstem, and widespread, diffuse microglia and T-cell infiltrations with neuronal loss and astrogliosis, most severe in the frontal and temporal lobes. Mild, perivascular lymphocyte T infiltrations involved particularly small and medium-sized vessels and were associated with brainstem ischaemic lesions. The neuropathological picture confirmed diagnosis of encephalomyelitis, which together with the clinical course suggested association with RA. Concluding, encepha-lomyelitis due to RA remains a challenging, controversial entity that needs further research and the establishment of effective diagnostic and treatment guidelines.

Tripeptidyl Peptidase 1 (TPP1) Deficiency in a 36-Year-Old Patient with Cerebellar-Extrapyramidal Syndrome and Dilated Cardiomyopathy.

We report on a 36-year-old man with cerebellar-extrapyramidal syndrome and severe heart failure because of dilated cardiomyopathy of unknown origin. Dysarthria and cardiac arrhythmia began at early childhood (4 years of age). Brain MRI (28 years of age) demonstrated severe cerebellar atrophy. At the age 32, he presented with dysarthria, ataxia, dystonia, and tremor of the right hand, bilateral slowed neural conduction in the visual pathways, and decreased mental acuity. At the age of 33 years, the patient underwent cardiac transplantation because of severe dilated cardiomyopathy. In the TPP1 gene, biallelic variants were identified: previously reported p.(Leu13Pro) and novel p.(Tyr508Cys) variant. Additionally, hemizygous novel missense variant in the ABCD1 gene was inherited from the mother p.(Arg17His). Normal very-long-chain fatty acids (VLCFA) levels both in patient and his mother excluded ABCD1 mutation as the pathogenic one. Tripeptidyl peptidase 1 (TPP1) activity was reduced (8,8 U/mg protein/h; reference range: 47.4 ± 10.7). In light microscopy the biopsy specimens obtained from explanted heart showed severe myocyte hypertrophy with perinuclear vacuolization with inclusions. Electron microscopy revealed absence of lipofuscin accumulation, no ultrastructural curvilinear profiles, fingerprint bodies, or granular osmiophilic deposits (GRODs) in lysosomes. As described here, the patient presents clinical symptoms observed in benign forms of ceroid lipofuscinosis type 2 (CLN2) and simultaneously some features of autosomal recessive spinocerebellar ataxia type 7 (SCAR7), which is also caused by mutations in the TPP1 gene.

Morphological and ultrastructural changes in Herpes simplex encephalomyelitis: an attempt to determinate the etiological factor.

Herpes simplex encephalomyelitis (HSE) is a rare disease with a high mortality rate. Correct diagnosis is established on the basis of the combination of the clinical and investigative features. Unfortunately, precise diagnosis remains difficult due to several clinical similarities and false negative or inconclusive results of diagnostic tests. Here, we present two cases of HSE together with the morphological and ultrastructural picture. The first case was a 45-year-old man with acute symptoms of encephalitis, and the other one was a 28-year-old woman presenting subacute encephalomyelitis. Both cases had negative serologic and molecular results for Herpes simplex in the blood and cerebrospinal fluid. Brain and spinal cord samples taken from both cases were stained typically with histological and immunohistochemical methods and small tissue fragments were examined with the transmission electron microscope (TEM). Microscopic examination confirmed viral encephalomyelitis in both cases. An electron micrograph showed typical intranuclear viral particles inside of damaged neurons, which together with topography of brain and spinal cord changes suggest HHV-1/HHV-2 in the first case and/or HHV-3 in the other case. Thus, morphological and ultrastructural examinations may be a useful tool to set up correct diagnosis and help to determine the pathogenic factor in patients suspected of viral encephalomyelitis.

POLG gene mutation. Clinico-neuropathological study.

We present a female patient with a mutation of the POLG gene (POLG DNA polymerase gamma, catalytic subunit; *174763) in which the clinical course suggested a mitochondrial disease, a neuropathological examination identified the syndrome more closely, and a genetic test confirmed the disease. Apart from the morphological lesions typical of Alpers-Huttenlocher syndrome, rarely observed symmetrical degenerative changes in the accessory olivary nuclei were found. It was unusual in the clinical course of the disease that pancreatitis was diagnosed before symptoms of liver failure appeared.

Clinical and ultrastructural findings in an ataxic variant of Kufor-Rakeb syndrome.

INTRODUCTION: Kufor-Rakeb syndrome (KRS) is a rare autosomal recessive neurodegenerative disorder manifesting as juvenile-onset atypical parkinsonism with pyramidal signs, supranuclear gaze palsy, dementia and characteristic minimyoclonus, with a notable phenotype variability. The responsible gene ATP13A2 was also associated with hereditary spastic paraplegia, uncomplicated early - or late-onset parkinsonism and a form of neuronal ceroid lipofuscinosis. We present clinical and ultrastructural findings in a 28-year-old woman with novel biallelic ATP13A2 mutations. MATERIAL AND METHODS: An ultrastructural study of the skin and muscle sample was carried out. Sequence analysis of all protein coding exons and exon-intron boundaries of genes was performed on patient's genomic DNA. A proprietary oligonucleotide-selective sequencing method was used for capturing genomic targets and sequencing was performed using Illumina sequencing system. RESULTS: The patient presented with juvenile-onset progressive parkinsonian syndrome and cognitive deterioration, accompanied by mild spastic paraplegia, supranuclear gaze palsy, cerebellar syndrome, peripheral neuropathy and fine myoclonus. Plentiful and varied osmiophilic deposits were found in skin and muscle biopsy. Sequence analysis identified two novel heterozygous variants in ATP13A2: a nonsense variant c.2209C>T, p.(Gln737*) and a 2-bp deletion c.2366_2367delTC, p.(Leu789Argfs*15) causing a frameshift leading to a premature stop codon. Oral levodopa treatment was initiated resulting in marked improvement of bradykinesia, rigidity, speech and swallowing. CONCLUSIONS: We report two novel ATP13A2 pathogenic mutations, further expanding the phenotype of Kufor-Rakeb syndrome with the unusual features of ataxia and polyneuropathy. We thoroughly describe ultrastructural findings and document a meaningful response to levodopa.

Neurogenesis in adult human brain after hemorrhage and ischemic stroke.

INTRODUCTION: Adult neurogenesis includes proliferation and differentiation of progenitor cells as well as their migration and maturation. In the adult human brain, two neurogenic regions, the hippocampal dentate gyrus (DG) and the subventricular zone (SVZ) of lateral ventricles, have been identified. In the dentate gyrus, three types of transcriptionally active cells and in the subventricular zone, four types of transcriptionally active cells, including GFAP-positive neural stem cells (NSCs), have been differentiated. MATERIAL AND METHODS: The aim of the study was to identify and compare density of neurogenic cells between two study groups of patients (7 men, 7 women, mean age 70 ± 6.03) with ischemic stroke and with hemorrhage (6 men, 2 women, mean age 64.75 ± 12.23) and the control group of patients (6 men, 2 women, mean age 64 ± 10.95) free of neuropathologic changes who died suddenly within less than 10 min. RESULTS: In both groups, in the hippocampal dentate gyrus and in the subventricular zone of lateral ventricles, the presence of single GFAP-positive neural stem cells and the transcriptionally active cells labelled with phosphorylated histone H3Ser-10 (p-Histone H3Ser-10)/neural progenitor cells (NPCs), was observed. The quantitative analysis of cells with p-Histone H3Ser-10 expression in the hippocampal DG revealed significant differences between the hemorrhage and control groups (p = 0.001, test t). However, in the SVZ, it showed a statistically significant decrease in the density of transcriptionally active cells in the group of patients with ischemic stroke (p = 0.001, test t). A distinct decrease in the density of transcriptionally active cells, proportional to the length of the patients' hospitalization, was observed. CONCLUSIONS: Hypoxia belongs to pathomechanic factors responsible for ischemic stroke, which can induce neurogenesis. However, hypoxia along with ischemia and other factors implicated in ischemic stroke, such as the patient's age or duration of ischemia can have a decisive influence on the decrease in the density of transcriptionally active cells in this pathologic process.

Pathology of skeletal muscle fibers and small blood vessels in MERRF syndrome: an ultrastructural study.

Our studies concerned skeletal muscle biopsy specimens from a patient with clinically suspected MERRF syndrome, confirmed by genetic tests showing the presence of point mutation in the m.8344A> G in the tRNALys gene. Ultrastructurally, extensive damage of mitochondria in skeletal muscle fibres was observed, including the presence of two types of mitochondrial inclusions. Mild damage of mitochondria was revealed in small blood vessels and the presence of calcium deposits in the vascular walls were observed. The differences in mitochondrial damage may be related to different origin and expenditure of biologically useful energy in these cells.

Pathology of mitochondria in MELAS syndrome: an ultrastructural study.

Ultrastructural changes in skeletal muscle biopsy in a 24-year-old female patient with clinically suspected mitochondrial encephalomyopathy lactic acidosis and stroke-like episodes (MELAS) syndrome are presented. We observed proliferation and/or pleomorphism of mitochondria in skeletal muscle and smooth muscle cells of arterioles, as well as in pericytes of capillaries. Paracrystalline inclusions were found only in damaged mitochondria of skeletal muscle. Genetic testing revealed a point mutation in A3243G tRNALeu(UUR) typical for MELAS syndrome. We conclude that differentiated pathological changes of mitochondria in the studied types of cells may be associated with the different energy requirements of these cells.

Blood vessel ultrastructural picture in a CADASIL patient diagnosed at an advanced age.

We report the case of an 84-year-old male patient afflicted by cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) showing minimal symptoms of disease. The patient was diagnosed on the basis of ultrastructural and genetic examinations. Ultrastructurally, a typical vascular pathology was found. However, in abnormal capillary vessel walls no granular osmiophilic material (GOM) was found. In the arteriole there were only a few GOM deposits that revealed various structures, of which only some resembled typical round GOM. The arteriolar walls showed severe damage, including fragmentation, degeneration and loss of vascular smooth muscle cells (VSMCs) with numerous deposits of elastin, mucosubstances, different granular debris, as well as collagen fibres in the basement membrane. Lysosomal inclusions with fingerprint morphology, atypical for CADASIL, were located in some of the VSMCs. Very old age at the onset of the disease may suggest that morphological changes in blood vessels, described in this report, may be due to both the disease and the patient's age. To our best knowledge it is the first description of pathology of blood vessels and GOM morphology in a CADASIL patient diagnosed at an advanced age.

Frontotemporal lobar degeneration with MAPT mutation in an Italian-Polish family. A case report.

Frontotemporal lobar degeneration (FTLD) with mutations in the MAPT (microtubule-associated protein tau) gene (FTLD with MAPT mutation) is a neurodegenerative disease with various clinical phenotypes. We present an Italian- Polish family with a IVS10+3G>A mutation in the MAPT gene, linked with haplotype H1s in a male proband (Fig. 2, II.2, H1s/H1b diplotype) and his sister (Fig. 2, II.1, the H1s/H1j diplotype). This report presents clinical, neuropathological and genetic testing of the proband and his affected sister, two members of an Italian-Polish family consisting of 25 family members. Their clinical history includes dementia as well as movement and cardiovascular disorders. Magnetic resonance imaging showed frontal and temporal cerebral atrophy. Neuropathological studies of the brain samples showed loss of neurons, gliosis, and the occurrence of neurofibrillary tangles, numerous neuropil threads, coiled bodies and abundant deposits of tau protein, including 3- and 4-repeated isoforms in neurons and glial cells. Only in the male proband brain, there were Pick body-like deposits in granule neurons of the hippocampus. Pathology of vascular walls was found in both cases. Ultrastructurally, the male proband showed clusters of collagen fibers mainly in a pericyte position. Beside the typical neurofibrillary pathology, aggregated gliofilaments and lipofuscin deposits in astroglia are described. Our report suggests that FTLD with IVS10+3G>A MAPT mutation causes damage mainly to the central nervous system and induces neuropathological changes, depending on the haplotypes of MAPT. In the clinical course of this disease, damage of the cardiovascular system may also be observed.

Alcohol-induced changes in the developing cerebellum. Ultrastructural and quantitative analysis of neurons in the cerebellar cortex.

Maternal ethanol consumption during pregnancy may cause foetal alcohol syndrome (FAS). Our experiments of ethanol-treated female rats were based on the FAS model in humans; therefore, the results obtained may help explain the clinical mechanism of the disease development. The ultrastructural examination of the cerebellar cortex of ten-day-old rat pups of ethanol-treated dams during pregnancy (group IA), pregnancy and lactation (group IIA), and lactation (group IIIA) revealed that alcohol administration leads to a delayed maturation of Purkinje cells. This was most strongly manifested in the pups of dams treated with ethanol during pregnancy and lactation. Moreover, this study showed degenerative changes in Purkinje cells as well as in granular layer cells in all experimental groups. There was a difference in the ultrastructural picture of both types of dying cells, which might result from different time frame of their sensitivity to ethanol administration. The quantitative analysis showed the most pronounced decrease in the density of Purkinje cells in the posterior superior fissure of cerebellar cortex in the pups of dams treated with ethanol during pregnancy.