Altered amyloid-β structure markedly reduces gliosis in the brain of mice harboring the Uppsala APP deletion

Deposition of amyloid beta (Aβ) into plaques is a major hallmark of Alzheimer's disease (AD). Different amyloid precursor protein (APP) mutations cause early-onset AD by altering the production or aggregation properties of Aβ. We recently identified the Uppsala APP mutation (APPUpp), which causes Aβ pathology by a triple mechanism: increased β-secretase and altered α-secretase APP cleavage, leading to increased formation of a unique Aβ conformer that rapidly aggregates and deposits in the brain. The aim of this study was to further explore the effects of APPUpp in a transgenic mouse model (tg-UppSwe), expressing human APP with the APPUpp mutation together with the APPSwe mutation. Aβ pathology was studied in tg-UppSwe brains at different ages, using ELISA and immunohistochemistry. In vivo PET imaging with three different PET radioligands was conducted in aged tg-UppSwe mice and two other mouse models; tg-ArcSwe and tg-Swe. Finally, glial responses to Aβ pathology were studied in cell culture models and mouse brain tissue, using ELISA and immunohistochemistry. Tg-UppSwe mice displayed increased β-secretase cleavage and suppressed α-secretase cleavage, resulting in AβUpp42 dominated diffuse plaque pathology appearing from the age of 5-6 months. The γ-secretase cleavage was not affected. Contrary to tg-ArcSwe and tg-Swe mice, tg-UppSwe mice were [11C]PiB-PET negative. Antibody-based PET with the 3D6 ligand visualized Aβ pathology in all models, whereas the Aβ protofibril selective mAb158 ligand did not give any signals in tg-UppSwe mice. Moreover, unlike the other two models, tg-UppSwe mice displayed a very faint glial response to the Aβ pathology. The tg-UppSwe mouse model thus recapitulates several pathological features of the Uppsala APP mutation carriers. The presumed unique structural features of AβUpp42 aggregates were found to affect their interaction with anti-Aβ antibodies and profoundly modify the Aβ-mediated glial response, which may be important aspects to consider for further development of AD therapies.

CRISPR-Cas9 treatment partially restores amyloid-β 42/40 in human fibroblasts with the Alzheimer's disease PSEN 1 M146L mutation

Presenilin 1 (PS1) is a central component of γ-secretase, an enzymatic complex involved in the generation of the amyloid-β (Aβ) peptide that deposits as plaques in the Alzheimer's disease (AD) brain. The M146L mutation in the PS1 gene (PSEN1) leads to an autosomal dominant form of early-onset AD by promoting a relative increase in the generation of the more aggregation-prone Aβ42. This change is evident not only in the brain but also in peripheral cells of mutation carriers. In this study we used the CRISPR-Cas9 system from Streptococcus pyogenes to selectively disrupt the PSEN1 M146L allele in human fibroblasts. A disruption of more than 50% of mutant alleles was observed in all CRISPR-Cas9-treated samples, resulting in reduced extracellular Aβ42/40 ratios. Fluorescence resonance energy transfer-based conformation and western blot analyses indicated that CRISPR-Cas9 treatment also affects the overall PS1 conformation and reduces PS1 levels. Moreover, our guide RNA did not lead to any detectable editing at the highest-ranking candidate off-target sites identified by ONE-seq and CIRCLE-seq. Overall, our data support the effectiveness of CRISPR-Cas9 in selectively targeting the PSEN1 M146L allele and counteracting the AD-associated phenotype. We believe that this system could be developed into a therapeutic strategy for patients with this and other dominant mutations leading to early-onset AD.

PET Imaging in Preclinical Anti-Aβ Drug Development

Positron emission tomography (PET), a medical imaging technique allowing for studies of the living human brain, has gained an important role in clinical trials of novel drugs against Alzheimer’s disease (AD). For example, PET data contributed to the conditional approval in 2021 of aducanumab, an antibody directed towards amyloid-beta (Aβ) aggregates, by showing a dose-dependent reduction in brain amyloid after treatment. In parallel to clinical studies, preclinical studies in animal models of Aβ pathology may also benefit from PET as a tool to detect target engagement and treatment effects of anti-Aβ drug candidates. PET is associated with a high level of translatability between species as similar, non-invasive protocols allow for longitudinal rather than cross-sectional studies and can be used both in a preclinical and clinical setting. This review focuses on the use of preclinical PET imaging in genetically modified animals that express human Aβ, and its present and potential future role in the development of drugs aimed at reducing brain Aβ levels as a therapeutic strategy to halt disease progression in AD.

Brain pharmacokinetics of two BBB penetrating bispecific antibodies of different size

Background

Transferrin receptor (TfR1) mediated enhanced brain delivery of antibodies have been studied extensively in preclinical settings. However, the brain pharmacokinetics, i.e. brain entry, distribution and elimination are still not fully understood for this class of antibodies. The overall aim of the study was to compare the brain pharmacokinetics of two BBB-penetrating bispecific antibodies of different size (210 vs 58 kDa). Specifically, we wanted to investigate if the faster systemic clearance of the smaller non-IgG antibody di-scFv3D6-8D3, in comparison with the IgG-based bispecific antibody mAb3D6-scFv8D3, was also reflected in the brain.

Methods

Wild-type (C57/Bl6) mice were injected with ¹²⁵I-iodinated ([¹²⁵I]) mAb3D6-scFv8D3 (n = 46) or [¹²⁵I]di-scFv3D6-8D3 (n = 32) and euthanized 2, 4, 6, 8, 10, 12, 16, or 24 h post injection. Ex vivo radioactivity in whole blood, peripheral organs and brain was measured by γ-counting. Ex vivo autoradiography and nuclear track emulsion were performed on brain sections to investigate brain and parenchymal distribution. Capillary depletion was carried out at 2, 6, and 24 h after injection of [¹²⁵I]mAb3D6-scFv8D3 (n = 12) or [¹²⁵I]di-scFv3D6-8D3 (n = 12), to estimate the relative levels of radiolabelled antibody in brain capillaries versus brain parenchyma. In vitro binding kinetics for [¹²⁵I]mAb3D6-scFv8D3 or [¹²⁵I]di-scFv3D6-8D3 to murine TfR were determined by LigandTracer.

Results

[¹²⁵I]di-scFv3D6-8D3 showed faster elimination from blood, lower brain C_max, and T_max, a larger parenchymal-to-capillary concentration ratio, and a net elimination from brain at an earlier time point after injection compared with the larger [¹²⁵I]mAb3D6-scFv8D3. However, the elimination rate from brain did not differ between the antibodies. The study also indicated that [¹²⁵I]di-scFv3D6-8D3 displayed lower avidity than [¹²⁵I]mAb3D6-scFv8D3 towards TfR1 in vitro and potentially in vivo, at least at the BBB.

Conclusion

A smaller size and lower TfR1 avidity are likely important for fast parenchymal delivery, while elimination of brain-associated bispecific antibodies may not be dependent on these characteristics.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12987-021-00257-0.

Long-Term Effects of Traumatic Brain Injury in a Mouse Model of Alzheimer's Disease

Alzheimer’s disease (AD) is the leading cause of dementia worldwide, affecting over 10% of the elderly population. Epidemiological evidence indicates that traumatic brain injury (TBI) is an important risk factor for developing AD later in life. However, which injury-induced processes that contribute to the disease onset remains unclear. The aim with the present study was to identify cellular processes that could link TBI to AD development, by investigating the chronic impact of two different injury models, controlled cortical impact (CCI) and midline fluid percussion injury (mFPI). The trauma was induced in 3-month-old tg-ArcSwe mice, carrying the Arctic mutation along with the Swedish mutation, and the influence of TBI on AD progression was analyzed at 12- and 24-weeks post-injury. The long-term effect of the TBI on memory deficiency, amyloid-β (Aβ) pathology, neurodegeneration and inflammation was investigated by Morris water maze, PET imaging, immunohistochemistry, and biochemical analyses. Morris water maze analysis demonstrated that mice subjected to CCI or mFPI performed significantly worse than uninjured tg-ArcSwe mice, especially at the later time point. Moreover, the injured mice showed a late upregulation of reactive gliosis, which concurred with a more pronounced Aβ pathology, compared to uninjured AD mice. Our results suggest that the delayed glial activation following TBI may be an important link between the two diseases. However, further studies in both experimental models and human TBI patients will be required to fully elucidate the reasons why TBI increases the risk of neurodegeneration.

Interaction studies of the human and Arabidopsis thaliana Med25-ACID proteins with the herpes simplex virus VP16- and plant-specific Dreb2a transcription factors

Mediator is an evolutionary conserved multi-protein complex present in all eukaryotes. It functions as a transcriptional co-regulator by conveying signals from activators and repressors to the RNA polymerase II transcription machinery. The Arabidopsis thaliana Med25 (aMed25) ACtivation Interaction Domain (ACID) interacts with the Dreb2a activator which is involved in plant stress response pathways, while Human Med25-ACID (hMed25) interacts with the herpes simplex virus VP16 activator. Despite low sequence similarity, hMed25-ACID also interacts with the plant-specific Dreb2a transcriptional activator protein. We have used GST pull-down-, surface plasmon resonance-, isothermal titration calorimetry and NMR chemical shift experiments to characterize interactions between Dreb2a and VP16, with the hMed25 and aMed25-ACIDs. We found that VP16 interacts with aMed25-ACID with similar affinity as with hMed25-ACID and that the binding surface on aMed25-ACID overlaps with the binding site for Dreb2a. We also show that the Dreb2a interaction region in hMed25-ACID overlaps with the earlier reported VP16 binding site. In addition, we show that hMed25-ACID/Dreb2a and aMed25-ACID/Dreb2a display similar binding affinities but different binding energetics. Our results therefore indicate that interaction between transcriptional regulators and their target proteins in Mediator are less dependent on the primary sequences in the interaction domains but that these domains fold into similar structures upon interaction.

Interactions between DNA, transcriptional regulator Dreb2a and the Med25 mediator subunit from Arabidopsis thaliana involve conformational changes

Mediator is a multiprotein coregulatory complex that conveys signals from DNA-bound transcriptional regulators to the RNA polymerase II transcription machinery in eukaryotes. The molecular mechanisms for how these signals are transmitted are still elusive. By using purified transcription factor Dreb2a, mediator subunit Med25 from Arabidopsis thaliana, and a combination of biochemical and biophysical methods, we show that binding of Dreb2a to its canonical DNA sequence leads to an increase in secondary structure of the transcription factor. Similarly, interaction between the Dreb2a and Med25 in the absence of DNA results in conformational changes. However, the presence of the canonical Dreb2a DNA-binding site reduces the affinity between Dreb2a and Med25. We conclude that transcription regulation is facilitated by small but distinct changes in energetic and structural parameters of the involved proteins.

Myofibroblasts in the normal conjunctival surface

PURPOSE

To investigate the occurrence of myofibroblasts (MFBs) in the normal conjunctival surface and to evaluate any anatomical and time-related variations.

METHODS

MFBs were screened among healthy individuals (35 eyes) by collecting impression cytology (IC) samples from the bulbar conjunctiva. A cohort of volunteers (12 eyes) was followed for 1 year by taking two to five imprints every month. MFBs were identified by immunohistochemical localization of the MFB marker alpha-smooth-muscle actin (alpha-SMA).

RESULTS

Using a filter imprint technique, MFBs were found consistently in 94% of samples from the conjunctival surface of participating individuals. The overall MFB levels, expressed as percentage of all cells on the filter, were highest in March-May [mean 4.1%, standard deviation (SD) +/- 1.5] and lowest in December-February (mean 1.2%, SD +/- 0.5). The difference was statistically significant [p < 0.0005, Friedman test, one-way repeated measures analysis of variance (anova)]. Moreover, there was a clear divergence of MFB density between the nasal, temporal, superior and inferior bulbar conjunctiva (mean 1.7%, 1.9%, 22% and 9.7%, respectively).

CONCLUSION

MFBs, known as a cellular constituent of granulation tissue in wound healing, occur in the normal conjunctival surface, which is a novel finding. Our results also show that MFB level follows a seasonal variation pattern in a temperate climate, increasing in April-September and decreasing in October-March. This variation might reflect a degree of a transient or ongoing state of tissue repair after conjunctival trauma or stress caused by exposure to environmental factors.

[PiSZ-phenotype alpha 1-antitrypsin deficiency: a rare cause of bronchiectasis]

Panacinar emphysema is the most characteristic pulmonary disease in patients with alpha1-antitrypsin deficiency (AAT). Bronchiectasis can also arise with AAT deficiency, although the association is much less common and no clear cause-effect relationship has yet been established. We report the case of a woman who presented with bronchiectasis and PiSZ-phenotype ATT deficiency, without emphysema. A review of the literature showed that the case is exceptional.

[Prevalence and risk factors of respiratory symptoms in farmers; comment]

BACKGROUND

A cross-sectional study was performed to determine the prevalence of respiratory symptoms in farmers and to assess occupational risk factors for respiratory symptoms in this population.

METHOD

A questionnaire on respiratory symptoms and occupation was mailed to a sample of 1,191 farmers with descriptive analysis of the symptoms and multivariate analysis through logistic modeling to assess the different risk factors.

RESULTS

1,164 workers answered the questionnaire (response index 98.2%) and 808 subjects were finally included in the study after discarding non exposed workers. The highest prevalences of asthma symptoms (39.2%) and symptoms of nasal allergy (31.6%) were found in poultry workers (p < 0.001, chi square). Sheep workers showed the highest prevalences of chronic phlegm (38.5%), work-related symptoms (53.9%) and symptoms of organic dust toxic syndrome (35.9%) (p < 0.005, chi square). At multivariate analysis, adjusting for age, gender, smoking and other occupational exposures, poultry work was a risk factor for asthma symptoms (OR 2.1; IC 95% 1.2-3.8) and symptoms of nasal allergy (OR 2.3, IC 95% 1.3-4.2), and dairy farming a risk factor for chronic phlegm (OR 1.8, IC 95% 1.1-2.9). Agriculture was not associated with respiratory symptoms.

CONCLUSION

In our study risk factors for respiratory symptoms in Spanish farmers were poultry and dairy farming.

[Synchronous multiple primary cancer of the lung: a rare association of small cell carcinoma as the main tumor plus epidermoid carcinoma]

Multiple primary cancer (MPC), a rare finding, is most often seen in the breast. In the lung, this cancer is rare (accounting for between 1.5 and 3% of cases), with epidermoid carcinoma usually being the principal tumor. The presentation of small-cell carcinoma as the principal tumor in MPC is thought to be extremely rare. The criteria for pulmonary MPC described by Martini and Melamed continue to provide the definition of reference. Pulmonary MPC can manifest in a synchronically (simultaneous appearance) or metachronically (with more than two years' lapse in appearance). Patients so-affected are usually male and heavy smokers. Survival with this type of lung cancer is usually less than for a single form. We report the case of a patient with synchronous MPC of the lung, with small cell carcinoma as the principal tumor associated with epidermoid carcinoma. We review the literature on this subject.

An unusual presentation of secondary pleural hydatidosis

Although pleural involvement is relatively common in cystic hydatid disease, one of the rarest and least known complications is secondary pleural hydatidosis. We report the case of a patient who presented with polycystic secondary pleural hydatidosis 4 yrs after treatment for a pyopneumothorax caused by rupture of a pulmonary cyst near the pleural space. Due to the coexistence of severe chronic obstructive pulmonary disease, surgery was ruled out. The patient was treated with albendazole, with a favourable outcome.

[Mediastinal non-Hodgkin's lymphoma: atypical presentation diagnosed with bronchoscopy]

Primary mediastinal non-Hodgkin lymphoma is a rare entity that can manifests with secondary pulmonary involvement. The case of a 37 years-old man patient with non-Hodgkin lymphoma mixed B-cell, which was diagnosed by means of bronchoscopic biopsy, is presented. His characteristics clinical and radiologic presentation, and diagnostic usefulness of fiberoptic bronchoscopy, is remarked. We revised clinical and pathologic features of interests for this lymphoproliferative disorders with thoracic involvement.

Maximum inspiratory and expiratory pressures have no daytime variation in healthy men

The variation of maximal respiratory pressures (Pimax and Pemax) in healthy subjects were studied on the same day in 16 non-smoking healthy men (age 26.2 +/- 3.2 years). The Pimax and Pemax were obtained on three occasions (8 a.m., 2 p.m. and 9 p.m.) within the same day. There were no differences between readings for Pimax and Pemax values.

[Efficacy and tolerance of the treatment of tuberculosis in the aged]

We analyzed 55 confirmed cases of tuberculosis in patients over 65, a sample that amounted to 9% of all patients seen in our practice over a period of 5 years. Mean age was 72.4 and the male/female ratio was 4/1. The most frequently associated diseases were tobacco addiction (49%), chronic obstructive pulmonary disease (33%), alcoholism (25%) and prior diagnosis of tuberculosis (20%). Lung involvement was the most common clinical presentation (76%), followed by pleural (9%) and skeletal (7%) involvement. The clinical picture was non specific, with 13% remaining asymptomatic. Cough was the most frequent symptom (45%) and unilateral apical fibrosis with ulceration was the most frequent radiological finding. Pleural discharge and cavitation were demonstrated in 14 and 22%, respectively. Scarring was visible on X-rays in 44%. The tuberculin test was positive in 88% of the cases in which it was performed. Mean delay in diagnosis was 3.4 months; 62% were diagnosed by sputum test, 11% by culture, and 27% histology. In 4% death was directly caused by tuberculosis. Three patients withdrew from treatment, in one case treatment failed, and there was one relapse detected at follow-up. We observed adverse side effects in 33%, and found no statistically significant differences between the 2 therapeutic protocols used (2 months RHS/7 months RH and 2 months RHZS/4 months RH). The incidence of tuberculosis among the elderly is low in our practice and the entity behaves much as it does in the rest of the adult population. Both the efficacy and tolerance of treatment can be considered optimal.

Idiopathic bronchiolitis obliterans organizing pneumonia with multiple cavitary lung nodules

Bronchiolitis obliterans organizing pneumonia (BOOP) is a pulmonary disorder with a wide spectrum of radiological features. We report the case of a 58 year old woman, in whom the radiological appearance was multiple cavitary nodules in both lungs, that responded with a complete resolution after corticosteroid therapy. This finding justifies the inclusion of BOOP in the differential diagnosis of multiple cavitary nodules.

Asbestos bodies in normal lung of western Mediterranean populations with no occupational exposure to inorganic dust

The aim of this study was to determine the following: (a) asbestos body count in lung tissue of different western Mediterranean populations; (b) the association, if any, of urban industrial residence with higher lung tissue asbestos exposure posed for lung cancer in our population. Lung-tissue samples were studied in three groups of subjects from the general population: (1) group A comprised 18 patients from Barcelona's urban industrial area (mean age = 62.2 y, standard deviation [SD] = 13.6); (2) group B comprised 16 patients who lived in a rural area of Albacete in the south of Spain (mean age = 62.2 y, SD = 13.7); and (3) group C comprised 8 patients who had been diagnosed with lung cancer, who lived in or near Barcelona, and who had never been exposed occupationally to asbestos (mean age = 62.1 y, SD = 7.4). A wet lung/dry lung weight ratio was determined. In group A, asbestos bodies were observed in 9 of 18 (50%) subjects, and asbestos bodies numbered 52.35 per g dry lung (SD = 101.72) (upper limit of normality [higher value] = 430.12 asbestos bodies per g dry lung). In group B, asbestos bodies were observed in 2 of 16 (12.5%) subjects, and asbestos bodies numbered 5.37 per g dry lung (SD = 8.79) (upper limit normality = 35.15 asbestos bodies per g dry lung). In group C, we observed asbestos bodies in 2 of 8 subjects (25.0%), and asbestos bodies numbered 20.59 per g dry weight (SD = 24.10).(ABSTRACT TRUNCATED AT 250 WORDS)

[Diffuse mediastinal lipomatosis and exogenous obesity]

A case of diffuse mediastinal lipomatosis (ML) is described, associated to exogenous obesity, infrequent entity, which is comprehended within the causes which can cause mediastinal broadening. The clinical characteristics of our observation and the general aspects of interest are reviewed for this type of mediastinal affectation.

Changes in the ribonucleoprotein constituents of the nucleus during the differentiation of muscle cells in the chick embryo

The ribonucleoprotein components of the nucleus of chick embryo muscle cells in different stages of development were studied by electron microscopic quantitative stereology. The changes of the constituents were related with the appearance of the innervation by means of silver impregnation for light microscope. The numerical density of the perichromatin granules (PCG) is low in mononuclear cells and myotubes. It is noteworthy that the frequency of the PCG does not change during the transition of the cells in mitotic cycle to postmitotic myoblasts and during myofibril differentiation. However, there is an important increment in this parameter when the motor nerve fibers arrive at the muscle and the synaptic contacts are established. This change is correlated with appearance, or at least with a great increase, of the importance of posttranscriptional controls of the expression of some genes. The augmentation in the frequency of PCG is not accompanied by alterations of the abundance of total RNP particles, in close resemblance with the phenomena occurring in neuroblast during the differentiation of synaptic endings. The variations of the nucleolar volume coincide with the changes in rRNA synthesis.

Postural variation of the maximum inspiratory and expiratory pressures in obese patients

Evaluating whether weight is a factor responsible for the decrease of muscle force in the supine position with respect to the upright and sitting positions, we measured maximum inspiratory and expiratory pressures (PImax and PEmax) in these postures in ten obese patients (age 38.7 +/- 9.1 years; height 168.7 +/- 8.9 cm; and weight 139.3 +/- 28.4 kg) and ten normal control subjects (age 38.4 +/- 8.2 years; height 169.3 +/- 7.9 cm and weight 66.9 +/- 11.9 kg.) In both study groups, PImax and PEmax values decreased in the supine posture with respect to upright and sitting positions. Differences between pressures in the various postures were similar for both groups with the exception of PEmax in obese females. The decrease in PEmax values from the sitting to supine positions was greater in obese than control females. Weight, sex and postural changes can influence the generation of maximal expiratory force.

Pulmonary mass and air meniscus sign in a 19-year-old man

Sacrococcygeal teratoma is rarely diagnosed in adults. Pulmonary mass as the presenting clinical form of the malignant variety of this germ-cell tumor is exceptional. We report herein such a case with the noticeable peculiarity of showing the air meniscus sign on chest roentgenographic examination.

Comparative study of Legionella pneumophila and other nosocomial-acquired pneumonias

We studied, in a prospective way, the characteristics of definitively diagnosed nosocomially acquired pneumonias in our hospital over 36 months. Out of 55 cases, 27 were due to Legionella pneumophila and 28 to other, non-Legionella bacteria. The cases of legionellosis concentrated in July, August, and December. The only risk factors that showed significant differences (p less than 0.05) were general anesthesia and surgery and immunosuppressive disease, which were more frequent in the non-Legionella group, as were chronic liver disease and lowering of consciousness level. The absence of severe underlying disease, chronic or not, was uncommon in both groups, but more frequent in the Legionella group. We observed no differences in the clinical features of the two groups. Mean values of gamma-glutamyltranspeptidase and total bilirubin were higher (p less than 0.05) in the non-Legionella group. The only x-ray data that showed significant difference were pleural effusion, more frequent in the non-Legionella group (p less than 0.02). The mortality rate of legionellosis was 14.6 percent compared to 35.7 percent for the non-Legionella group (p less than 0.05). We conclude that a sure differential diagnosis based on clinical, roentgenographic and analytical features of both groups is not possible. The relatively low mortality rate of the Legionella group, when compared to other series of nosocomial legionellosis, could be due to the standard use of erythromycin in the therapeutic approach to nosocomial-acquired pneumonia in our hospital.

The length of time healthy subjects and patients with chronic obstructive pulmonary disease are able to withstand maximal inspiratory pressure

We measured the length of time that healthy subjects and patients with chronic obstructive pulmonary disease (COPD) were able to withstand an inspiratory pressure equal to or over 80% of the maximal static inspiratory pressure (PImax). For the purpose 10 patients with COPD, during a stable period of their illness, and 10 healthy subjects were studied. The mean values for PImax, maximal expiratory pressure (PEmax) and the length of time to withstand PImax (TPImax) were significantly lower in patients with COPD than in healthy individuals. In the group of patients with COPD, 50% exhibited a TPImax of less than 3 s and none were able to withstand PImax for more than 4.30 s. However, it should be pointed out that, even among healthy individuals, there were 4 subjects who were unable to withstand PImax for more than 3 s.

Tuberculosis of the breast: a rare modern disease

A case of mammary tuberculosis is reported. A communication between the axillary glands and the breast emphasises Cooper's theory that the breast becomes secondarily involved by lymphatic extension. Involvement of other organs by acid-fast bacilli could not be demonstrated. A relapse occurred sixteen months after a 6-month course of treatment with rifampicin, isoniazid, ethambutol and pyrazinamide.