Browsing by study line "Cross-disciplinary translational medicine"

The APOE4 gene variant of apolipoprotein E (apoE) has been identified as a predisposing factor for late-onset Alzheimer’s disease (AD). ApoE is known to interact with one of the classically characterized hallmarks of AD, the amyloid-beta (Aβ) protein. Aβ activates the classical complement pathway by binding to C1q that may sustain inflammation, hamper Aβ clearance and therefore promote accumulation of Aβ deposits in the brain and affect the integrity of the blood-brain barrier. Depending on context, binding of apoE to C1q can either activate or inhibit complement activation. ApoE can also interact with the complement regulator factor H (FH) which colocalizes with C1q on Aβ plaques. The interactions between these proteins and their role in the AD pathogenesis has not been fully explored. This thesis aimed at unraveling the complex formation between Aβ1-42, apoE, FH, and C1q, and their role in complement activation to provide novel insights on the mechanisms contributing to AD pathophysiology. By conducting enzyme-linked immunosorbent assays and Western Blotting of native PAGE, I was able to show that FH bound to apoE and forms a complex with Aβ1-42/apoE in an isoform- specific manner (apoE2 > apoE3 > apoE4) whereas C1q bound all Aβ1-42/apoE complexes with same affinity. FH did not bind Aβ1-42 alone, thus the results indicated that binding of FH in Aβ1-42/apoE complex took place via apoE2 and apoE3. In the absence of FH and C1q, immobilized Aβ1-42/apoE4 complexes led to higher serum complement activation levels when compared to Aβ1-42/apoE2 and Aβ1-42/apoE3 complexes or Aβ1-42 alone. C1q activated serum complement especially in the presence of Aβ1-42/apoE3 and Aβ1-42/apoE4. Further functional analysis with flow cytometry revealed that in fluid phase the presence of FH could restrict Aβ1-42-induced complement activation, the subsequent formation of C5a and activation of C5a receptor (C5aR) expressed on Human embryonic kidney (HEK) 293 cells. The presence of all apoE isoforms on Aβ1-42/C1q complexes led to reduced C5aR activation. Surprisingly, however, the reduction was the largest with apoE4, and the presence of C1q on Aβ1-42 alone could also decrease C5aR activation. The results of this thesis elucidated the effects of Aβ1-42, apoE, C1q and FH in complement activation and proposed a mechanism by which FH regulates complement activation and cell-mediated inflammation through isoform-specific binding to apoE associated with Aβ1-42. Further work is required to analyze the functional effects of these complexes, whether Aβ1-42, apoE, FH, and C1q can all bind simultaneously to form a large complex and whether this complex affects C5aR activation. This study provides important insights on how APOE4 may predispose to the neurotoxicity and neuroinflammatory changes in AD pathophysiology early in the disease process. Yet, the findings are only preliminary and therefore further studies are required to validate these results and to demonstrate whether promoting FH binding to apoE/Aβ complex could provide a novel target for AD therapy.

Every childbirth is a unique experience for a mother and the whole family. While there is growing evidence that childbirth has long-term implications for a mother’s life, and that a personal childbirth experience is in a major role in determining those implications, personal birth experiences have not yet come to the centre of labour care in Finland. In this qualitative study I investigated the constitutive elements of personal childbirth experiences. The material consisted of 29 birth stories written by 20 mothers, collected as a part of a larger research project Battles over Birth – Finnish Birth Culture in Transition (2020-2023), funded by the Kone Foundation. I divided the stories into positive and negative experiences based on how mothers described the events and their implications. I analysed the role of pain management in all experiences, after which other elements were identified from each story and compared within category and finally between categories. In addition, I analysed the long-term implications of positive and negative experiences for mothers. Systematic content analysis suggested three elements as crucial in determining whether the experience was valued as positive or negative, and these were: 1) pain and pain management, 2) interaction with professionals, and 3) sense of control and self-determination. The birth experience had implications on the mother-infant bond, mental health, trust toward health care professionals, number of subsequent children, general well-being, and confidence in motherhood. The birth experience thus constitutes of several aspects and can have significant long-term implications. By considering mothers’ wishes and treating them respectfully, not only is their constitutional right for self-determination respected, but a safe and comfortable environment can be created for labour. The findings of this study can contribute to developing maternity and childbirth care toward patient-centred care, where personal birth experiences have more value and positive birth experiences can be ensured.

Antibiotic-resistant bacteria present a severe threat to global health. The future treatment of common bacterial infections relies on the identification of novel antibiotics and targets in the present. One area of antimicrobial research is the study of bacteriophage (Petrovic Fabijan et al.) mechanisms and the identification of phage-derived antimicrobials. Sequenced phage genomes are largely (>70%) annotated as “hypothetical proteins of unknown function” (HPUFs) and investigation into HPUFs with a toxic effect on host bacteria (toxHPUFs) aims to reveal new antibacterial targets and antimicrobials. Next-generation sequencing and plating-based toxicity screening of Staphylococcus phage Stab21 HPUFs identified nine HPUFs that incurred toxicity to Escherichia coli. In this study, the tightly controlled tetracycline-inducible plasmid pRAB11N was used as a shuttle vector and verified the toxicity of five out of nine HPUFs to E. coli and revealed that no HPUFs caused toxicity to the Stab21 natural target and clinically relevant Staphylococcus aureus. These results suggest that screening for toxHPUFs should be carried out in closely related bacterial species or the phages’ natural host. The five toxHPUFs of E. coli were further characterised by protein function and structural predictions. Only one toxHPUF, g024, returned a reliable model with homology to Bacillus phage SPO1 homing endonuclease I-HmuI, yet the role of this DNase in bacterial host toxicity is still unknown. To determine the bacterial targets of the toxHPUFs, spontaneous toxin-insensitive mutants of the five toxHPUFs were investigated. For three toxHPUFs, the toxin insensitivity was ascribed to the elimination of the toxin-encoding gene. However, toxin-insensitive g172 and g187 sequences revealed mutations in the tetR gene of pRAB11N that led to the inability of tetracycline binding and thus no induction of gene expression and did not aid in identifying the bacterial targets of these toxHPUFs. This study highlights the experimental complexities of phage-derived antimicrobial research. It also maintains the value of this research strategy, with the verification of HPUFs with a toxic effect on E. coli and accompanied future studies of bacterial target determination having the potential to uncover novel antimicrobial mechanisms that can be exploited for therapeutic application.