Effect of intranasal stem cell administration on the nigrostriatal system in a mouse model of Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide. It affects the locomotor system, leading to a final severe disability through degeneration of dopaminergic neurons. Despite several therapeutic approaches used, no treatment has been proven to be effective; however, cell therapy may be a promising therapeutic method. In addition, the use of the intranasal (IN) route has been advocated for delivering various therapies to the brain. In the present study, the IN route was used for administration of mesenchymal stem cells (MSCs) in a mouse model of PD, with the aim to evaluate IN delivery as an alternative route for cell based therapy administration in PD. The PD model was developed in C57BL/6 mice using intraperitoneal rotenone administration for 60 consecutive days. MSCs were isolated from the mononuclear cell fraction of pooled bone marrow from C57BL/6 mice and incubated with micrometer-sized iron oxide (MPIO) particles. For IN administration, we used a 20 µl of 5×10⁵ cell suspension. Neurobehavioral assessment of the mice was performed, and after sacrifice, brain sections were stained with Prussian blue to detect the MPIO-labeled MSCs. In addition, immunohistochemical evaluation was conducted to detect tyrosine hydroxylase (TH) antibodies in the corpus striatum and dopaminergic neurons in the substantia nigra pars compacta (SNpc). The neurobehavioral assessment revealed progressive deterioration in the locomotor functions of the rotenone group, which was improved following MSC administration. Histopathological evaluation of brain sections in the rotenone+MSC group revealed successful delivery of MSCs, evidenced by positive Prussian blue staining. Furthermore, rotenone treatment led to significant decrease in dopaminergic neuron number in SNpc, as well as similar decrease in the corpus striatum fiber density. By contrast, in animals receiving IN administration of MSCs, the degeneration caused by rotenone treatment was significantly counteracted. In conclusion, the present study validated that IN delivery of MSCs may be a potential safe, easy and cheap alternative route for stem cell treatment in neurodegenerative disorders.

Association of Osteopontin Gene Polymorphisms with Colorectal Cancer

We investigated the association of the Osteopontin (OPN) (rs9138 and rs1126616) polymorphisms with colorectal cancer (CRC). One hundred CRC patients and 112 healthy individuals were subjected to OPN (rs9138 and rs1126616) genotyping and measurement of OPN protein plasma level. The C allele of OPN rs1126616 and the CC haplotype were significantly higher in CRC patient (p = 0.036, 0.003, respectively). In females, the C allele of OPN rs9318 (A/C) polymorphism was significantly associated with increased CRC risk (p = 0.036). The plasma OPN level >104.35 ng/mL was significantly associated with CRC. Our findings suggest a significant role played by OPN (rs9138 and rs1126616) in colorectal carcinogenesis.

Direct Observation versus Endoscopic Video Recording-Based Rating with the Objective Structured Assessment of Technical Skills for Training of Laparoscopic Cholecystectomy

Purpose: The validated Objective Structured Assessment of Technical Skills (OSATS) score is used for evaluating laparoscopic surgical performance. It consists of two subscores, a Global Rating Scale (GRS) and a Specific Technical Skills (STS) scale. The OSATS has accepted construct validity for direct observation ratings by experts to discriminate between trainees' levels of experience. Expert time is scarce. Endoscopic video recordings would facilitate assessment with the OSATS. We aimed to compare video OSATS with direct OSATS. Methods: We included 79 participants with different levels of experience [58 medical students, 15 junior residents (novices), and 6 experts]. Performance of a cadaveric porcine laparoscopic cholecystectomy (LC) was evaluated with OSATS by blinded expert raters by direct observation and then as an endoscopic video recording. Operative time was recorded. Results: Direct OSATS rating and video OSATS rating correlated significantly (ρ = 0.33, p = 0.005). Significant construct validity was found for direct OSATS in distinguishing between students or novices and experts. Students and novices were not different in direct OSATS or video OSATS. Mean operative times varied for students (73.4 ± 9.0 min), novices (65.2 ± 22.3 min), and experts (46.8 ± 19.9 min). Internal consistency was high between the GRS and STS subscores for both direct and video OSATS with Cronbach's α of 0.76 and 0.86, respectively. Video OSATS and operative time in combination was a better predictor of direct OSATS than each single parameter. Conclusion: Direct OSATS rating was better than endoscopic video rating for differentiating between students or novices and experts for LC and should remain the standard approach for the discrimination of experience levels. However, in the absence of experts for direct rating, video OSATS supplemented with operative time should be used instead of single parameters for predicting direct OSATS scores.

Tau protein as a biomarker for asphyxia: A possible forensic tool?

Asphyxial death has been a problem for forensic investigations due to the absence of a validated biomarker for the diagnosis of this event. Recently, research on brain affection by asphyxia raised hopes on the possible use of CNS markers for asphyxia. The cytoskeletal proteins seem to be attractive targets as they are vulnerable to hypoxia and can be affected in asphyxial deaths. Tau, an important cytoskeletal protein, showed affection in many neurodegenerative disorders and recently in some acute incidences like trauma and brain ischemia. In this report we show the affection of the normal pattern of tau and pathological aggregates of tau in the case of brain hypoxia. This may give new clues to asphyxial death investigations.

Mesh versus acellular dermal matrix in immediate implant-based breast reconstruction - A prospective randomized trial

BACKGROUND

Comparative studies on the use of meshes and acellular dermal matrices (ADM) in implant-based breast reconstruction (IBBR) have not yet been performed.

METHODS

This prospective, randomized, controlled, multicenter pilot study was performed at four Austrian breast cancer centers. Fifty patients with oncologic or prophylactic indication for mastectomy and IBBR were randomized to immediate IBBR with either an ADM (Protexa(®)) or a titanized mesh (TiLOOP(®) Bra). Complications, failed reconstruction, cosmetic outcome, patients' quality of life and the thickness of the overlying tissue were recorded immediately postoperatively and 3 and 6 months after surgery.

RESULTS

48 patients participated in the study (Protexa(®) group: 23; TiLOOP(®) Bra group: 25 patients). The overall complication rate was 31.25% with similar rates in both groups (Protexa(®) group: 9 versus TiLOOP(®) Bra group: 6; p = 0.188). There was a higher incidence of severe complications leading to failed reconstructions with implant loss in the Protexa(®) group than in the TiLOOP(®) Bra group (7 versus 2; p < 0.0001). An inverted T-incision technique led to significantly more complications and reconstructive failure with Protexa(®) (p = 0.037, p = 0.012, respectively). There were no significant differences in patients' satisfaction with cosmetic results (p = 0.632), but surgeons and external specialists graded significantly better outcomes with TiLOOP(®) Bra (p = 0.034, p = 0.032).

CONCLUSION

This pilot study showed use of TiLOOP(®) Bra or Protexa(®) in IBBR is feasible leading to good cosmetic outcomes and high patient satisfaction. To validate the higher failure rates in the Protexa(®) group, data from a larger trial are required. NCT02562170.

Effect of lifestyle and reproductive factors on the onset of breast cancer in female BRCA 1 and 2 mutation carriers

BACKGROUND

The birth year-dependent onset of breast cancer (BC) in BRCA1/2 mutation carriers suggests a risk-modifying role for reproductive and life style factors. We therefore examined possible associations between these factors and age at diagnosis.

METHODS

Cox regression analysis and log-Rank testing were used to estimate the effect of potential life style factors on the onset of BC in 197 BRCA mutation carriers.

RESULTS

Nulliparous BRCA mutation carriers developed BC earlier than those who had delivered (36.4 vs. 40.9; P = 0.001). Similarly, smokers and women who had used oral contraceptives experienced an earlier cancer onset (39.0 vs. 41.4; P = 0.05 and 39.3 vs. 44.9; P = 0.0001, respectively). In multivariate analysis, oral contraceptive use (HR: 1.7; P = 0.006) and birth cohort (< vs. ≥1965 HR: 4.5; P = 0.001) were associated with an earlier BC onset, while previous pregnancies led to a delay (HR: 0.2; P = 0.04). Mutation carriers born ≥1965 were less likely to have experienced pregnancies and more likely to have used oral contraceptives, and consequently developed BC at an earlier age (median age: 42 vs. 58; P < 0.0001 log-Rank test).

CONCLUSION

We here demonstrate that in BRCA1/2 mutation carriers the birth cohort-associated differences in the onset of BC are profound and influenced by reproductive factors.

Interobserver agreement and accuracy of non-invasive diagnosis of endometriosis by transvaginal sonography

OBJECTIVES

To evaluate interobserver agreement and accuracy of transvaginal sonography (TVS) in diagnosing deep infiltrating endometriosis (DIE) and endometriomas.

METHODS

A total of 67 consecutive patients referred to a pelvic pain clinic and scheduled for laparoscopy were enrolled in the study between January 2013 and January 2014. Patients were independently examined prospectively by two experienced sonographers (Observers A and B) who were blinded to the other's results. For the two observers, Gwet's first-order agreement coefficient (Gwet's AC1) was used to calculate interobserver agreement and diagnostic accuracy, as well as sensitivity, specificity, positive (PPV) and negative (NPV) predictive values using TVS, as compared to laparoscopy, for diagnosing DIE and endometriomas.

RESULTS

Among the 67 patients enrolled, 65 were analyzed. For the diagnosis of DIE and endometriomas by TVS, the level of agreement (Gwet's AC1) between Observers A and B and sensitivity/specificity values for the respective Observers were, by site: vagina (Gwet's AC1, 0.933; 62%/94% and 82%/94%), bladder (Gwet's AC1, 1.00; 67%/97% and 67%/97%), uterosacral ligaments (Gwet's AC1, 0.84; 73%/83% and 53%/90%), adnexa (Gwet's AC1, 0.95; 71%/93% and 71%/93%), rectovaginal septum (Gwet's AC1, 0.95; 40%/90% and 33%/87%) and rectosigmoid (Gwet's AC1, 0.98; 93%/96% and 94%/98%) which reflected high interobserver agreement. With the exception of sensitivity of diagnosis of DIE affecting the RVS, similar results were observed when TVS was compared with laparoscopy.

CONCLUSIONS

TVS is a highly accurate and reproducible method for non-invasive diagnosis of DIE by well-trained professionals.

Technetium-99m thyroid scan; does it have a diagnostic aid in sub-clinical auto-immune thyroid disease in systemic lupus erythematosus patients?

PURPOSE

Technetium-99m (Tc-99m) thyroid scintigraphy is a well known diagnostic tool that shows the entire gland in a single image. We aimed to evaluate its additive diagnostic value in subclinical autoimmune thyroid disease (S-AITD) in systemic lupus erythematosus (SLE) patients.

METHODS

We investigated 100 systemic lupus erythematosus (SLE) patients without overt thyroid involvement (eight men and 92 women; mean age 40±6.5 years) and 50 age and sex matched controls. All were subjected to thyroid evaluation using anti-thyroglobulin (anti-TG) and anti-thyroid peroxidase (anti-TPO) antibodies; hormones (FT3; FT4 and TSH) and Tc-99m thyroid scintigraphy.

RESULTS

14/100 (14%) and none (0%) were positive for S-AITD in SLE and control groups, respectively (P = 0.0001). They were classified by thyroid scintigraphy and hormonal profile into 2/14 Hashimoto; 10/14 atrophic thyroiditis and 2/14 Graves' disease. Anti-TPO was elevated in 12 SLE cases, while anti-TG was elevated in only 2/14 (P = 0.0001). Thyroid scintigraphy showed statistically significant associations with FT4, TSH and anti-TPO.

CONCLUSION

Tc-99m thyroid scintigraphy may have an additional diagnostic role in S-AITD among SLE patients, with an impact on patient management. This potential needs to be further evaluated in a larger series on a multicenter basis.

Effect of sexual diary keeping and self-evaluation on female sexual function and depression: A pilot study

OBJECTIVES

The aim of the trial was to assess the effect of self-evaluation and sexual diary keeping on female sexual function and depressive symptoms in women diagnosed with sexual dysfunction.

METHODS

A single-arm non-randomised trial included 30 women (53 ± 7 years of age) with female sexual dysfunction (Female Sexual Function Index [FSFI] < 27) and a stable partnership duration of 5-40 years. Female sexual function was assessed by sexual, psychological and gynaecological history taking and validated questionnaires including the FSFI, Female Sexual Distress Scale (FSDS) and Hamilton Depression Scale (HDS), before and after 4 weeks of sexual diary keeping.

RESULTS

A subjective improvement in communication of sexual problems was reported by 60% of participants; no participants reported any worsening of communication. FSFI and FSDS scores were, respectively, 18.0 ± 7.7 and 22.0 ± 10.0 at baseline and 20.2 ± 7.2 and 20.6 ± 11.5 after 4 weeks. HDS score decreased from 6.0 ± 4.0 at baseline to 4.4 ± 2.7 after 4 weeks (p = 0.042).

CONCLUSIONS

Self-evaluation and sexual diary keeping may improve aspects of sexual life, such as couple communication, without a direct effect on variables measured with validated questionnaires on different domains of sexual function.

Developmental neurotoxic effects of Malathion on 3D neurosphere system

Developmental neurotoxicity (DNT) refers to the toxic effects induced by various chemicals on brain during the early childhood period. As human brains are vulnerable during this period, various chemicals would have significant effects on brains during early childhood. Some toxicants have been confirmed to induce developmental toxic effects on CNS; however, most of agents cannot be identified with certainty. This is because available animal models do not cover the whole spectrum of CNS developmental periods. A novel alternative method that can overcome most of the limitations of the conventional techniques is the use of 3D neurosphere system. This in-vitro system can recapitulate many of the changes during the period of brain development making it an ideal model for predicting developmental neurotoxic effects. In the present study we verified the possible DNT of Malathion, which is one of organophosphate pesticides with suggested possible neurotoxic effects on nursing children. Three doses of Malathion (0.25 μM, 1 μM and 10 μM) were used in cultured neurospheres for a period of 14 days. Malathion was found to affect proliferation, differentiation and viability of neurospheres, these effects were positively correlated to doses and time progress. This study confirms the DNT effects of Malathion on 3D neurosphere model. Further epidemiological studies will be needed to link these results to human exposure and effects data.

Comparative study between quantitative digital image analysis and fluorescence in situ hybridization of breast cancer equivocal human epidermal growth factor receptors 2 score 2(+) cases

Background:

Optimization of workflow for breast cancer samples with equivocal human epidermal growth factor receptors 2 (HER2)/neu score 2⁺ results in routine practice, remains to be a central focus of the on-going efforts to assess HER2 status. According to the College of American Pathologists/American Society of Clinical Oncology guidelines equivocal HER2/neu score 2⁺ cases are subject for further testing, usually by fluorescence in situ hybridization (FISH) investigations. It still remains on open question, whether quantitative digital image analysis of HER2 immunohistochemistry (IHC) stained slides can assist in further refining the HER2 score 2⁺.

Aim of this Work:

To assess utility of quantitative digital analysis of IHC stained slides and compare its performance to FISH in cases of breast cancer with equivocal HER2 score 2⁺.

Materials and Methods:

Fifteen specimens (previously diagnosed as breast cancer and was evaluated as HER 2^- score 2⁺) represented the study population. Contemporary new cuts were prepared for re-evaluation of HER2 immunohistochemical studies and FISH examination. All the cases were digitally scanned by iScan (Produced by BioImagene [Now Roche-Ventana]). The IHC signals of HER2 were measured using an automated image analyzing system (MECES, www.Diagnomx.eu/meces). Finally, a comparative study was done between the results of the FISH and the quantitative analysis of the virtual slides.

Results:

Three out of the 15 cases with equivocal HER2 score 2⁺, turned out to be positive (3⁺) by quantitative digital analysis, and 12 were found to be negative in FISH too. Two of these three positive cases proved to be positive with FISH, and only one was negative.

Conclusions:

Quantitative digital analysis is highly sensitive and relatively specific when compared to FISH in detecting HER2/neu overexpression. Therefore, it represents a potential reliable substitute for FISH in breast cancer cases, which desire further refinement of equivocal IHC results.

NDUFA12L mitochondrial complex-I assembly factor: Implications for taupathies

There is a strong correlation between taupathies and the development and progression of neurodegenerative disorders. Abnormal tau becomes hyperphosphorylated and dissociated from microtubules with the aggregation of intracellular tau aggregates within the patient's brain. The current review is divided into two broad sections. In the first section we discuss the molecular biology and the clinicopathologic features of taupathies. While in the second section we discuss the relationship between mitochondrial complex-I and taupathies. Polymorphism in NDUFA12L may be a crucial factor for development of neurodegenerative taupathies. Thus NDUFA12L screening may be an early biomarker for identifying risk groups for such disorders.

Abstract P5-02-06: Digital quantification of estrogen receptor expression in normal breast in post-menopausal women with breast cancer and association with tumor subtypes

Background: ER expression in normal breast epithelium (NBR) is higher in women with a history of breast cancer (BC) compared to controls. In adjuvant setting, metanalysis showed effective Tamoxifen treatment was restricted to ER positive cancers. However, it is also known prophylactic oophorectomy (a form of estrogen suppression) significantly reduces the incidence of BC in BRCA1 carriers. This is in contrast with the 80% rate of ER negative tumors in BRCA1 patients. The aim of this study is to quantify ER expression in NBR away from tumor in women with BC and to correlate it with BC subtypes.

Methods: 204 consecutive patients were identified for whom NBR away from tumor was available. 27 reduction mammoplasty (RM) tissues from women with no history of BC were used as controls. Tissue microarrays were constructed and slides were stained with ER and scanned using Aperio XT Scan Scope. Normal terminal duct lobular epithelium was manually circled on scanned images and annotations were recorded in separate digital layers. ER staining was quantitated in marked areas of the electronic image using an optimized scoring nuclear IHC algorithm (Aperio technologies, Inc., Vista, CA). Clinical information and tumor characteristics (menopausal status, ER, HER2 expression, grade, size, number of positive nodes, stage) were recorded based on pathology reports and tumor registry data.

Results: The mean ER positivity in NBR was 16 ± 12.4 % (range: 0-5-5.7%) for all patients with BC, 20.8±13.9% for postmenopausal (n=74) and 13.7 ±10.9% for peri+ premenopausal (n=170) subgroups. ER positivity was higher in patients with BC compared to those undergoing RM with no history of BC. ER positivity in NBR did not vary by tumor size, positive lymph nodes status, tumor grade, or stage in post-menopausal, and pre + perimenopausal women. Older age at diagnosis was significantly associated (p&lt;0.0001) with ER in NBR. In post- menopausal women ER expression in NBR was significantly higher in patients with ER negative or triple negative tumors.

Estrogen receptor expression in normal terminal duct lobular units of post-menopausal women with breast cancer in relation to tumor subtypes.  Postmenopausal (N=74)  NMean % (SD)P ValueTumor ER Status   0.05 Negative1427.4 (13.9)  Positive6019.3 (13.6) Tumor HER2 Status   0.34 Negative5721.8 (14.9)  Positive817.7 (5.7) Tumor Triple Negative   0.05 No5319.7 (13.6)  Yes1228.5 (14.7) HER2 status was not known in some cases and was excluded from statistical calculations.

Conclusion: This computer assisted image analysis study confirms ER expression in NBR increases with age and menopausal status in women with BC. We report, for the first time, a significant association between ER expression in normal breast epithelium with ER negative and triple negative cancers in post-menopausal women. Our study suggests that ER expression in normal epithelium may play a role in development of hormone receptor negative breast cancers.

Citation Format: H Evin Gulbahce, Cindy Blair, Carol Sweeney, Rachel Factor, Mohamed Salama. Digital quantification of estrogen receptor expression in normal breast in post-menopausal women with breast cancer and association with tumor subtypes [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-02-06.

Toll-like receptor 4 blocker as potential therapy for acetaminophen-induced organ failure in mice

Acetaminophen (APAP, 4-hydroxyacetanilide) is the most common cause of acute liver failure in the United States. In addition to exhibiting hepatotoxicity, APAP exerts a nephrotoxic effect may be independent of the induced liver damage. Toll-like receptors (TLRs) have been suggested as a potential class of novel therapeutic targets. The aim of the present study was to investigate the potential of the TLR-4 blocker TAK-242 in the prevention of APAP-induced hepato-renal failure. Four groups of C57BL mice were studied: Vehicle-treated/control (VEH), APAP-treated (APAP), N-acetyl cysteine (NAC)-pretreated plus APAP (APAP + NAC) and TAK-242-pretreated plus APAP (APAP + TAK) groups. Mice were clinically assessed then perfused 4 h later. Liver and kidney tissues were collected and examined histologically using basic hematoxylin and eosin staining to detect signs of necrosis and inflammation. Plasma samples were collected to measure the levels of alanine transaminase, aspartate transaminase and serum creatinine. In addition, liver and kidney tissues were assayed to determine the levels of reduced glutathione. The results of the present study indicate the potential role of TLR-4 in APAP-induced organ toxicity. In the APAP + TAK and APAP + NAC groups, histopathological examination indicated that pretreatment with TAK-242 or NAC afforded protection against APAP-induced injury. However, this protective effect was more clinically evident in the APAP + TAK group compared with the APAP + NAC group. The various biochemical parameters (serum enzymes and reduced glutathione) revealed no significant protection in either of the pretreated groups. Therefore, the present study indicated that the TLR-4 blocker had protective effects against acute APAP toxicity in liver and kidney tissues. These effects were identified clinically, histologically and biochemically. Furthermore, the TLR-4 blocker TAK-242 exhibited antioxidant properties in addition to anti-inflammatory effects.

Clinicopathologic evaluation of MYC expression in primary mediastinal (thymic) large B-cell lymphoma

OBJECTIVES

Based on previous molecular studies, a small fraction of primary mediastinal (thymic) large B-cell lymphoma (PMBL) demonstrates MYC alterations. However, no studies have evaluated MYC protein expression by immunohistochemistry (IHC) with follow-up fluorescence in situ hybridization (FISH) analysis. We aim to evaluate the clinicopathologic importance of MYC IHC expression in PMBL.

METHODS

Three pathologists independently evaluated MYC IHC expression in 32 cases of PMBL for percent tumor positivity and nuclear intensity. FISH analysis for MYC rearrangement was performed on cases with high MYC IHC expression. Clinical data including treatment, follow-up, and outcome were also reviewed in a subset of cases.

RESULTS

Variable MYC protein expression by IHC was detected in 30 (94%) of 32 cases of PMBL. One-third of the positive cases (10/30) showed high MYC IHC expression of at least 30% nuclear positivity. FISH analyses for MYC rearrangement on these 10 cases were negative. Review of clinical data on a subset of cases with high and low MYC IHC expression showed no differences in clinical outcome.

CONCLUSIONS

MYC protein expression by IHC is present in most PMBLs. Increased MYC protein expression can be seen in one-third of the cases; however, it does not correlate with genetic abnormalities by FISH. There is also no significant impact of MYC protein expression on clinical outcomes.

Characterization of mesenchymal stem cells derived from rat bone marrow and adipose tissue: a comparative study

Background and Objectives:

Stem cell technology offers a new hope for many chronic disorders patients. The types of stem cells are different with many differences existing between each type. Mesenchymal stem cells (MSCs) represent one type of adult stem cells that can be easily isolated, then re-transplanted to the patients. This offers potential for their future application in treating many disorders without fear of rejection possibility. MSCs can be isolated from different sources e.g. bone marrow (BMSCs) and adipose tissue (ADSCs). In the present study we compared BMSCs and ADSCs isolated from Sprague-Dawley rats.

Methods and Results:

For this comparison, immunophenotyping, the analysis of growth rates, proliferation by colony forming unit-fibroblast assay, population doubling time, and trilineage differentiation assays were performed for both BMSCs and ADSCs. The findings revealed that despite no difference in immunphenotypic character between BMSC and ADSC, a better proliferative capacity was observed for ADSCs which would advocate their better use in regenerative applications. On the other hand, BMSCs showed more potential for osteogenic and chondrogenic differentiation.

Conclusions:

Our study showed that, despite many similarities between both types of cells, there are differences existing which can offer assistance on choosing type of cell to be used in specific diseases. Although ADSCs seem more promising for regenerative application generally, BMSCs may represent a better choice for treating bone disorders.

Piericidin A aggravates Tau pathology in P301S transgenic mice

Objective

The P301S mutation in exon 10 of the tau gene causes a hereditary tauopathy. While mitochondrial complex I inhibition has been linked to sporadic tauopathies. Piericidin A is a prototypical member of the group of the piericidins, a class of biologically active natural complex I inhibitors, isolated from streptomyces spp. with global distribution in marine and agricultural habitats. The aim of this study was to determine whether there is a pathogenic interaction of the environmental toxin piericidin A and the P301S mutation.

Methods

Transgenic mice expressing human tau with the P301S-mutation (P301S^+/+) and wild-type mice at 12 weeks of age were treated subcutaneously with vehicle (N = 10 P301S^+/+, N = 7 wild-type) or piericidin A (N = 9 P301S^+/+, N = 9 wild-type mice) at a dose of 0.5 mg/kg/d for a period of 28 days via osmotic minipumps. Tau pathology was measured by stereological counts of cells immunoreative with antibodies against phosphorylated tau (AD2, AT8, AT180, and AT100) and corresponding Western blot analysis.

Results

Piericidin A significantly increased the number of phospho-tau immunoreactive cells in the cerebral cortex in P301S^+/+ mice, but only to a variable and mild extent in wild-type mice. Furthermore, piericidin A led to increased levels of pathologically phosphorylated tau only in P301S^+/+ mice. While we observed no apparent cell loss in the frontal cortex, the synaptic density was reduced by piericidin A treatment in P301S^+/+ mice.

Discussion

This study shows that exposure to piericidin A aggravates the course of genetically determined tau pathology, providing experimental support for the concept of gene-environment interaction in the etiology of tauopathies.