Michael K. Shaw

A combination of adoptive transfer and antigenic challenge induces consistent murine experimental autoimmune encephalomyelitis in C57BL/6 mice and other reputed resistant strains

Adoptive EAE was induced in SJL mice by the transfer of MBP-primed and in vitro-stimulated donor lymph node cells into naive syngeneic recipients. Priming donor mice with OVA instead of restimulating MBP-primed donor cell with OVA resulted in no transfer of EAE. This apparent lack of disease, however, could be overcome if the recipients were subsequently challenged with MBP. When this transfer-challenge technique was applied to BALB/c and C57BL/6 mice, these reputed (MBP)EAE-resistant strains developed consistent and severe disease similar to that seen in susceptible strains. In fact, a survey of eleven (MBP)EAE-resistant strains, defined on the basis of their inability to mount an encephalitogenic response in recipient mice following the transfer of MBP-primed and in vitro activated lymph node cells, revealed that EAE could be induced in all these strains. Since the surveyed strains represented a wide spectrum of genetic backgrounds as well as the common MHC congenic haplotypes (H-2b,d,k,m,r,s,v), it is concluded that the machinery for recognition of MBP, i.e. MHC genes and the appropriate T cell receptors, is functionally intact in these resistant mice. While MHC and T cell receptor genes are required for T cell responses, they are not the limiting factors that confer resistance in murine EAE.

Induction of myelin basic protein-specific experimental autoimmune encephalomyelitis in C57BL/6 mice: Mapping of T cell epitopes and T cell receptor Vβ gene segment usage

Early studies of murine experimental autoimmune encephalomyelitis (EAE) induced with myelin basic protein (MBP) divide various mouse strains into either “susceptible” or “resistant” phenotypes. Resistance is defined as lack of encephalitogenic responses after active immunization or adoptive transfer. It is now becoming clear that this unresponsiveness is not due to the inability of T cells to recognize MBP in the context of major histocompatibility complex (MHC) gene products. Using various manipulations, many laboratories are able to induce severe EAE in these strains. We previously reported that a combination of adoptive transfer and subsequent challenge of the recipients with MBP could overcome the resistance in many mouse strains (Shaw et al.: J Neuroimmunol 39:139–150, 1992). This approach now enables us to identify the encephalitogenic epitope and T cell receptor Vβ usage in a prototype strain, C57BL/6 (B6). Pepsin‐digested MBP fragments first located a major T cell epitope in a polypeptide containing residues 44–88. Overlapping synthetic peptides narrowed this epitope to p60–80. Truncated peptides from the carboxyl‐ or amino‐terminus further mapped a minimal peptide to p67–76. This encephalitogenic epitope appears to be unique to B6 mice. Independent encephalitogenic T cell clones specific for this epitope were also generated. Of six such clones analyzed, five different TCR Vβs were found. Whether unbiased usage of encephalitogenic TCR Vβ gene segments in B6 mice is related to its EAE resistant phenotype is not clear at this point.

T cells that trigger acute experimental autoimmune encephalomyelitis also mediate subsequent disease relapses and predominantly produce IL-17

Earlier studies showed that donor T cells that initiated a murine adoptive EAE persisted in the CNS of the recipients throughout the subsequent relapsing cycles. To clarify the functions of the persistent donor T cells in EAE relapsing disease, anti-Thy-1 antibodies were used to deplete these cells. Results showed that such treatment abrogated subsequent relapsing cycles in these animals. In addition, it was evident that a shift in cytokine profile occurred during acute and relapsing disease phases. These results unambiguously support the appropriateness of targeting T cells with specificity for the priming antigen in design of therapeutic approaches for MS.

DIFFERENTIAL LEVELS OF RESISTANCE TO DISEASE INDUCTION AND DEVELOPMENT OF RELAPSING EXPERIMENTAL AUTOIMMUNE ENCELPHALOMYELITIS IN TWO H-2b-RESTRICTED MOUSE STRAINS

Besides the major histocompatibility complex (MHC) genes, background genes are believed to influence the encephalitogenicity of SJL(H-2(s)) and B10.S (H-2(s)) mice responding to myelin basic protein (MBP). A new mouse strain was constructed to study the effects of the SJL genetic background in mice responding to H-2(b)-restricted neuroantigens. Although the SJL.B (H-2(b)) mouse remained resistant to MBP in active EAE induction, the disease severity was uniformly higher in MOG-induced active EAE and in MBP-induced adoptive EAE when compared to those of B6 (H-2(b)) mice. Treatment of mice with anti-CD25 antibodies prior to immunization caused 60% of SJL.B mice to become susceptible to MBP-induced EAE while only 14% of B6 mice were converted. In addition, MOG-induced EAE in SJL.B mice followed a remitting-relapsing disease course while B6 mice only exhibited monophasic or chronic episodes. The new SJL.B mouse strain provides a valuable tool for studying EAE resistance and remitting-relapsing disease in H-2(b) mice.

T-cells specific for a self-peptide of ApoB-100 exacerbate aortic atheroma in murine atherosclerosis

On the basis of mouse I-Ab-binding motifs, two sequences of the murine apolipoprotein B-100 (mApoB-100), mApoB-1003501–3515 (designated P3) and mApoB-100978–992 (designated P6), were found to be immunogenic. In this report, we show that P6 is also atherogenic. Immunization of Apoe−/− mice fed a high-fat diet (HFD) with P6 resulted in enhanced development of aortic atheroma as compared to control mice immunized with an irrelevant peptide MOG35–55 or with complete Freund’s adjuvant alone. Adoptive transfer of lymph node cells from P6-immunized donor mice to recipients fed an HFD caused exacerbated aortic atheromas, correlating P6-primed cells with disease development. Finally, P6-specific T cell clones were generated and adoptive transfer of T cell clones into recipients fed an HFD led to significant increase in aortic plaque coverage when compared to control animals receiving a MOG35–55-specific T cell line. Recipient mice not fed an HFD, however, did not exhibit such enhancement, indicating that an inflammatory environment facilitated the atherogenic activity of P6-specific T cells. That P6 is identical to or cross-reacts with a naturally processed peptide of ApoB-100 is evidenced by the ability of P6 to stimulate the proliferation of T cells in the lymph node of mice primed by full-length human ApoB-100. By identifying an atherogenic T cell epitope of ApoB-100 and establishing specific T cell clones, our studies open up new and hitherto unavailable avenues to study the nature of atherogenic T cells and their functions in the atherosclerotic disease process.

Maternal plasma LPCAT 1 mRNA correlates with lamellar body count

Abstract Human lysophosphatidylcholine acyltransferase 1 (hLPCAT1) is a protein which helps produce surfactant in the fetal lung. We previously reported that levels of cell-free fetal mRNA for hLPCAT1 in amniotic fluid are correlated with lamellar body count (LBC) (r2=0.93). This short communication demonstrates that fetal hLPCAT1 mRNA is also present in maternal blood. Its quantity also correlates with amniotic fluid LBC (r2=0.81). Research in maternal plasma hLPCAT1 may assist in understanding fetal and placental maturational processes.

Amniotic fluid LPCAT1 mRNA correlates with the lamellar body count

Abstract Lysophosphatidylcholine acyltransferase 1 (LPCAT1) is required in the biosynthesis of pulmonary surfactant. This short communication describes our assessment of LPCAT1 mRNA levels in human amniotic fluid. We found a direct correlation between LPCAT1 mRNA copies and the amniotic fluid lamellar body count (LBC). This finding corroborates an association between LPCAT1 and surfactant phospholipid biosynthesis in humans. It may provide a model for future research in perinatal medicine.

Gene therapy for multiple sclerosis

Recent advances in the field of immunology have increased our understanding of the pathology and regulation of autoimmune diseases. This knowledge is allowing the scientific community to consider the treatment of these diseases using new modalities of immunotherapy. The classic forms of therapy for autoimmune disease are directed at general suppression of the immune response. In contrast, newer forms of therapy are aimed at specific cells or cytokines that contribute to or regulate the aberrant immune response.