Release of nociceptin-like substances from the dorsal horn of rat spinal cords in situ was measured by the immobilized-antibody microprobe technique. Spinal cords removed from anesthetized 4-6 week-old rats were superfused with oxygenated Krebs solution at room temperature (21 ± 1°C). Glass microelectrodes, coated with antibodies to nociceptin, were inserted into the dorsal horn of the lumbar spinal cord (1.9 mm lateral to the midline to a depth 2.5 mm below the surface of the cord) for 15 rain periods before, during and after electrical stimulation applied to the dorsal root entry zone of the same segment. There was a basal release of immunoreactive nociceptin- like substance (irNC) from the dorsal horns during the pre-stimulation period. A significant increase in irNC release was detected during the period of electrical stimulation and this increase was maintained for at least 15 min following the cessation of electrical stimulation. These results provide the first evidence on the release of irNC, albeit non-quantitative, from the in situ rat spinal cord dorsal horn and an enhanced release upon electrical stimulation.

These studies examined the in vivo pharmacokinetics and efficacy of five anti-methamphetamine monoclonal antibodies (mAbs, KD values from 11 to 250 nM) in rats. While no substantive differences in mAb systemic clearance (t1/2 = 6.1-6.9 days) were found, in vivo function was significantly reduced within 1-3 days for four of the five mAbs. Only mAb4G9 was capable of prolonged efficacy, as judged by prolonged high methamphetamine serum concentrations. MAb4G9 also maintained high amphetamine serum concentrations, along with reductions in methamphetamine and amphetamine brain concentrations, indicating neuroprotection. The combination of broad specificity for methamphetamine-like drugs, high affinity, and prolonged action in vivo suggests mAb4G9 is a potentially efficacious medication for treating human methamphetamine-related medical diseases.

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京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20273号 / 医博第4232号 / 新制||医||1021(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 椛島 健治, 教授 山田 亮, 教授 清水 章 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

This document only includes an excerpt of the corresponding thesis or dissertation. To request a digital scan of the full text, please contact the Ruth Lilly Medical Library's Interlibrary Loan Department (rlmlill@iu.edu).

Anthrax Vaccine Adsorbed (AVA) immunization protects against anthrax disease by eliciting a neutralizing antibody response. However, antigen-specific antibody concentrations are not observed in high quantities until three immunizations have been administered over six months. Even then, humoral responses to AVA do not provide long-term immunity without an annual booster. We followed six healthy volunteers over the five-dose, 18-month AVA schedule to characterize the genetics of the immunoglobulin repertoire during the vaccination series. Two tiers of data were collected: 1) Immunoglobulin variable region genes (IgVRG) from bulk sorted naïve, memory and plasmablast (PB) B cells and 2) single cell sorted and sequenced IgVRG from plasmablasts. Samples were collected prior to and one and two weeks following each immunization. Our initial analyses indicated that technical error, the variation introduced by biological sampling and standard sample preparation, resulted in skewed output, and we developed a model to better estimate quantitative values from Ig-seq. We also utilized unique molecular identifiers to correct for nucleotide errors and PCR over-amplification. Our analysis of IgVRG following AVA administration reveals that the population of peripheral PBs following primary immunization is not distinguishable from the pre-immune peripheral PB repertoire. These PBs have more somatic mutations than expected for newly activated and differentiated naïve B cells, and are unlikely to be vaccine-elicited. In contrast, PBs observed following the 2nd dose have low mutation frequencies that increase upon subsequent vaccination. These clones are more persistent than clones first observed following any other immunization, but still make up a very small proportion of the overall repertoire. At no time is the clonal repertoire consistently dominated by a few clones, and the total and plasmablast repertoires are highly transient, even after the elicitation of vaccine-specific antibodies. AVA immunization thus results in a polyclonal B cell response which is not dominated by one or a few highly specific, strongly-elicited clones. We conclude that primary immunization by AVA is not sufficiently immunogenic to elicit vaccine-responsive, class-switched PBs to the periphery, nor is complete AVA immunization able to sustain proliferation of individual clones, providing insight into why AVA may require regular boosts.

Affinity maturation increases the affinity of B-cell derived antibodies to their cognate antigens. In this study, we characterized the kinetic, structural, dynamic and thermodynamic evolution of antibodies during affinity maturation. Through single B-cell cell sorting, paired heavy and light chain sequencing, phylogenetic analysis, antibody expression, and physicochemical characterization, we were able to longitudinally analyze the stages of affinity maturation of anti-PA (B.anthracis protective antigen) antibodies. Following repeated immunizations, we observed up to an 10,000-fold increase in antibody affinity, mainly through a decrease in the off-rates. For detailed maturation analysis, we chose three antibodies lying along a single clonal branch--the clone’s unmutated common ancestor (UCA), a medium affinity antibody (MAAb) appearing after second immunization, and a high-affinity antibody (HAAb) appearing after third immunization. Most of the mutations that occur between the UCA and HAAb resulted in key changes to structural conformation. In particular, mutations change residues in the CDR-H3 region inducing the folding of the CDR-loops into a conformation that is more complementary to PA. This advantageous new antibody conformation is preserved in the unbound state, indicating that though the UCA and MAAb appear to use an induced fit and/or conformational selection mechanism, the HAAb is more rigidly lock-and-key. Thermodynamic results support this interpretation. In the first maturation step from UCA to MAAb, enthalpic improvement indicates optimization of noncovalent interactions. The second step from MAAb to HAAb predominantly involves entropic improvement by which the advantageous conformation made accessible in the first step is made more dominant via the narrowing of effectively accessible conformations, which allows better contact with PA. This is also reflected by a less significant improvement in the enthalpic component of PA-binding. Studies examining the evolving protein-dynamic characteristics further support this interpretation. In summary, we observed that a single energetic component is not responsible for increased affinity in the maturation pathways we studied. From UCA to MAAb, affinity increases through optimization of noncovalent interactions. From MAAb to HAAb, affinity increase is achieved through changes that stabilize the favorable conformation in the unbound state. A better understanding of affinity maturation can have implications for antibody engineering and vaccine development.

The development of antibody-based drugs is continuing to expand at a rapid pace, especially for use at mucosal surfaces to prevent or treat infectious diseases and other conditions. A better understanding of how the Fc region of antibodies interacts with Fc-binding proteins at mucosal sites can inform an optimal design for antibody-based drugs. The Human Contraception Antibody (HCA) is a human IgG1 monoclonal antibody currently under development as a topical vaginal contraceptive. HCA binds to sperm via its Fab domains and causes rapid agglutination with other sperm in close proximity resulting in near complete immobilization of sperm over a wide area. In order to determine whether HCA participates in Fc-mediated functions in the female reproductive tract (FRT), we assessed the activity of HCA and engineered variants in three assays of Fc-mediated functions: complement-dependent cytotoxicity (CDC), antibody-dependent cellular phagocytosis (ADCP), and mucus trapping. The physiological relevance of CDC was confirmed by characterizing complement levels and activity in cervical mucus. Finally, we described the activity of a novel Fc receptor expressed by vaginal epithelium. With complement, HCA significantly reduced sperm motility and increased the number of lysed sperm via CDC. Additionally, human cervical mucus was found to have sufficient levels of complement to induce the classical complement cascade. HCA-opsonized sperm associated with macrophages and were phagocytosed via ADCP. HCA also trapped sperm in ovulatory human cervical mucus, significantly reducing their progression. Variants of HCA with mutated or obstructed Fc domains had decreased abilities to perform these Fc functions, while multivalent IgM-like and IgA variants of HCA were very effective in both sperm agglutination and Fc assays. We also investigated the novel expression of Fc alpha RI (CD89) by human vaginal epithelium and provide evidence that this Fc receptor may transport IgA through the mucosa. Basal application of IgA resulted in IgA in apical supernatants which was significantly reduced following treatment with a CD89 blocker. In summary, these studies provide an improved understanding of the possible Fc functions of HCA and other antibodies in the human FRT, including interactions with complement, cervical mucus, and Fc receptors. Determining which interactions can occur in vivo and which are desired for a specific indication can inform the design of mucosally applied antibody-based drugs like HCA, a much-needed novel contraceptive antibody.

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