Recent studies have been able to detect α-synuclein (αSyn) seeding in formaldehyde-fixed paraffin-embedded (FFPE) tissues from patients with synucleinopathies using seed amplification assays (SAAs), but with relatively low sensitivity due to limited protein extraction efficiency. With the aim of introducing an alternative option to frozen tissues, we developed a streamlined protein extraction protocol for evaluating disease-specific seeding in FFPE human brain. We evaluated the protein extraction efficiency of different tissue preparations, deparaffinizations, and protein extraction buffers using formaldehyde-fixed and FFPE tissue of a single Lewy body disease (LBD) subject. Alternatively, we incorporated heat-induced antigen-retrieval and dissociation using a commercially available kit. Our novel protein extraction protocol has been optimized to work with 10 sections of 4.5-µm-thickness or 2-mm-diameter micro-punch of FFPE tissue that can be used to seed SAAs. We demonstrated that extracted proteins from FFPE still preserve seeding potential and further show disease-specific seeding in LBD and multiple system atrophy. To the best of our knowledge, our study is the first to recapitulate disease-specific αSyn seeding behavior in FFPE human brain, with structural validation. Our findings open new perspectives in re-evaluating archived human brain tissue, extending the disease-specific seeding assays to larger cohorts to facilitate molecular subtyping of synucleinopathies.

Nucleosomes are non-uniformly distributed across eukarytic genomes, with stretches of ‘open’ chromatin strongly associated with transcriptionally active promoters and enhancers. Understanding chromatin accessibility patterns in normal tissue and how they are altered in pathologies can provide critical insights to development and disease. With the advent of high-throughput sequencing, a variety of strategies have been devised to identify open regions across the genome, including DNase-seq, MNase-seq, FAIRE-seq, ATAC-seq, and NicE-seq. However, the broad application of such methods to FFPE (formalin-fixed paraffin embedded) tissues has been curtailed by the major technical challenges imposed by highly fixed and damaged genomic material. Here we review the most common approaches for mapping open chromatin regions, recent optimizations to overcome the challenges of working with FFPE tissue, and a brief overview of a typical data pipeline with analysis considerations.

In the present study, we aimed to investigate whether an automated molecular diagnostic method based on PCR-reverse blot hybridization assay can discriminate between human Mycobacterium tuberculosis (MTB)-positive and -negative FFPE tissues and to compare the relative mRNA expression levels of various host immune markers between MTB-infected and uninfected human tissues using quantitative reverse transcription (qRT) PCR. A total of 52 human FFPE tissue samples from various regions of the body, including the lungs, lymph nodes, tendons, colon, and appendix, were collected and used for the molecular identification of Mycobacterium species and analysis of cytokine mRNA expression. As a result, IFN-γ, TNF-α, IP-10, CXCL9, CXCL11, and GM-CSF mRNA expression levels in MTB-infected tissues were significantly higher than those in uninfected samples. Additionally, the differences in the mRNA expression levels of IFN-γ, CXCL9, and GM-CSF between MTB-infected and uninfected tissues were statistically significant were statistically significant (p < 0.05). Correlation curve analysis indicated that the mRNA expression of IFN-γ was inversely proportional to that of IP-10 and that the mRNA expression levels of IFN-γ, TNF-α, CXCL9, CXCL11, GM-CSF, and TNFR were proportional and well-correlated. Furthermore, to establish marker profiles for detecting MTB infection, the statistically significant expression levels of three markers were combined. We confirmed that the combined profile of IFN-γ, CXCL9, and GM-CSF expression levels was statistically significant (P < 0.001). Although the mRNA expression patterns of host immune markers may vary according to MTB infection status, these patterns may be highly correlated and can be simultaneously used as an additional indicator for diagnosing TB.

Progesterone receptor (PGR) expression level determines biological characteristics of the serous ovarian carcinoma, and low PGR expression appears to be associated with chemoresistance and worse outcome. In this study, we aimed to find relationships between tumor progesterone receptor level and RNA-profile (miRNAs, piwiRNAs, and mRNAs), determining its biological characteristics and behavior. For this purpose, we applied next generation sequencing of small noncoding RNAs, quantitative RT-PCR, and immunohistochemistry to analyze FFPE and frozen tumor samples as well as blood plasma from patients with benign cystadenoma (BSC), serous borderline tumour (SBT), low-grade and high-grade serous ovarian carcinoma (LGSOC and HGSOC, respectively). We found significant upregulation of MMP7 and MUC16 and downregulation of PGR in LGSOC and HGSOC in comparison with BSC. The tissue content of miR-199a-5p, miR-214-3p, miR-424-3p, miR-424-5p, miR-125b-5p significantly inversely correlated with the expression level of MUC16 and blood serum CA125 concentration, and significantly directly correlated with the PGR expression level in tumor tissue. On the contrary, the tissue content of miR-16-5p, miR-17-5p, miR-20a-5p, miR-93-5p, responsible for epithelial-mesenchymal transition (EMT) of the cell, significantly directly correlated with the blood serum CA125 concentration and significantly inversely correlated with the PGR expression level in the tumor tissue. Levels of the EMT-associated miRNAs significantly directly correlated with the content of hsa_piR_022437, hsa_piR_009295, hsa_piR_020813, hsa_piR_004307, hsa_piR_019914 in tumor tissues. Among them, expression level of hsa_piR_004307 significantly inversly correlated with the PGR expression level in the tumor. Two optimal logistic regression models were developed based on the quantitation of hsa_piR_020813, miR-16-5p, hsa_piR_022437 or hsa_piR_004307, hsa_piR_019914, miR-93-5p in the tumor tissue, both of which significantly diagnose PGR-negative tumor phenotype with 93% sensitivity. According to FunRich3.1.3 functional enrichment analysis tool, 72 gene-targets of miRNA and piRNA identified here as markers of PGR-negative ovarian tumor phenotype were proven to be mutated in different cancers such as ovarian, breast, colorectal, liver, stomach, lung, endometrial, thyroid cancer. Among them, the blood plasma levels of miR-16-5p and hsa_piR_022437 can be used to diagnose PGR-negative tumor phenotype with 86% sensitivity before surgery and chemotherapy to choose the treatment strategy for this most aggressive type of ovarian cancer (for instance, neoadjuvant chemotherapy followed by cytoreduction in combination with hyperthermic intraperitoneal chemotherapy) to increase the effectiveness of treatment and longevity of the patient.