Host genetic regulation of acute MHV-4 viral encephalomyelitis and acute experimental autoimmune encephalomyelitis in (BALB/cKe x SJL/J) recombinant-inbred mice

Experimental Autoimmune Encephalomyelitis in the Mouse

This article details the materials and methods required for both active induction and adoptive transfer of experimental autoimmune encephalomyelitis (EAE) in the SJL mouse strain using intact proteins or peptides from the two major myelin proteins: proteolipid protein (PLP) and myelin basic protein (MBP). Additionally, active induction of EAE in the C57BL/6 strain using myelin oligodendrocyte glycoprotein (MOG) peptide is also discussed. Detailed materials and methods required for the purification of both PLP and MBP are described, and a protocol for isolating CNS-infiltrating lymphocytes in EAE mice is included. Modifications of the specified protocols may be necessary for efficient induction of active or adoptive EAE in other mouse strains. © 2021 Wiley Periodicals LLC. Basic Protocol: Active induction of EAE with PLP, MBP, and MOG protein or peptide Alternate Protocol: Adoptive induction of EAE with PLP-, MBP-, or MOG-specific lymphocytes Support Protocol 1: Purification of proteolipid protein Support Protocol 2: Purification of myelin basic protein Support Protocol 3: Isolation of CNS-infiltrating lymphocytes.

The Role of Host Genetic Factors in Coronavirus Susceptibility: Review of Animal and Systematic Review of Human Literature

BACKGROUND

The recent SARS-CoV-2 pandemic raises many scientific and clinical questions. One set of questions involves host genetic factors that may affect disease susceptibility and pathogenesis. New work is emerging related to SARS-CoV-2; previous work has been conducted on other coronaviruses that affect different species.

OBJECTIVES

We aimed to review the literature on host genetic factors related to coronaviruses, with a systematic focus on human studies.

METHODS

We conducted a PubMed-based search and analysis for articles relevant to host genetic factors in coronavirus. We categorized articles, summarized themes related to animal studies, and extracted data from human studies for analyses.

RESULTS

We identified 1,187 articles of potential relevance. Forty-five studies were related to human host genetic factors related to coronavirus, of which 35 involved analysis of specific genes or loci; aside from one meta-analysis on respiratory infections, all were candidate-driven studies, typically investigating small number of research subjects and loci. Multiple significant loci were identified, including 16 related to susceptibility to coronavirus (of which 7 identified protective alleles), and 16 related to outcomes or clinical variables (of which 3 identified protective alleles). The types of cases and controls used varied considerably; four studies used traditional replication/validation cohorts. Of the other studies, 28 involved both human and non-human host genetic factors related to coronavirus, 174 involved study of non-human (animal) host genetic factors related to coronavirus, 584 involved study of non-genetic host factors related to coronavirus, including involving immunopathogenesis, 16 involved study of other pathogens (not coronavirus), 321 involved other studies of coronavirus, and 18 studies were assigned to the other categories and removed.

KEY FINDINGS

We have outlined key genes and loci from animal and human host genetic studies that may bear investigation in the nascent host genetic factor studies of COVID-19. Previous human studies to date have been limited by issues that may be less impactful on current endeavors, including relatively low numbers of eligible participants and limited availability of advanced genomic methods.

Experimental autoimmune encephalomyelitis in the mouse

This unit details the materials and methods required for both active induction and adoptive transfer of experimental autoimmune encephalomyelitis (EAE) in the SJL mouse strain using intact proteins or peptides from the two major myelin proteins: proteolipid protein (PLP) and myelin basic protein (MBP). Detailed materials and methods required for the purification of both PLP and MBP are also described. A protocol for isolating CNS-infiltrating lymphocytes in EAE mice is included. Modifications of the specified protocols may be necessary for efficient induction of active or adoptive EAE in other mouse strains.

Experimental autoimmune encephalomyelitis in the mouse

This unit details the materials and methods required for both active induction and adoptive transfer of experimental autoimmune encephalomyelitis (EAE) in the SJL mouse strain using intact proteins or peptides from the two major myelin proteins: proteolipid protein (PLP) and myelin basic protein (MBP). Detailed materials and methods required for the purification of both PLP and MBP are also described. Modifications of the specified protocols may be necessary for efficient induction of active or adoptive EAE in other mouse strains.

Epitope spreading is not required for relapses in experimental autoimmune encephalomyelitis

The sequential emergence of specific T lymphocyte-mediated immune reactivity directed against multiple distinct myelin epitopes (epitope spreading) has been associated with clinical relapses in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). Based on this association, an appealing and plausible model for immune-mediated progression of the advancing clinical course in MS and EAE has been proposed in which epitope spreading is the cause of clinical relapses in T cell-mediated CNS inflammatory diseases. However, the observed association between epitope spreading and disease progression is not universal, and absolute requirements for epitope spreading in progressive EAE have not been tested in the absence of multiple T cell specificities, because most prior studies have been conducted in immunocompetent mouse strains that possessed broad TCR repertoires. Consequently, the precise nature of a causal relationship between epitope spreading and disease progression remains uncertain. To determine whether relapsing or progressive EAE can occur in the absence of epitope spreading, we evaluated the course of disease in mice which possessed only a single myelin-specific TCR. These mice (transgenic/SCID +/+) exhibited a progressive and sometimes remitting/relapsing disease course in the absence of immune reactivity to multiple, spreading myelin epitopes. The results provide direct experimental evidence relevant to discussions on the mechanisms of disease progression in MS and EAE.

Myelin basic protein-specific T lymphocytes induce chronic relapsing experimental autoimmune encephalomyelitis in lymphocyte-deficient (SCID) mice

Myelin basic protein (BP)-specific T lymphocyte cell lines were selected from the lymph nodes (LN) of BP-immunized, H-2d, CXJ-1 mice prior to the onset of clinical disease. These CD4+ T cells induced severe acute experimental autoimmune encephalomyelitis (EAE) in MHC-compatible (H-2d), lymphocyte-deficient (SCID) mice (C.B-17scid/scid). The incidence of disease was much higher in immunodeficient SCID mice (71%) than in syngeneic immunocompetent CXJ-1 mice (5%). SCID mice with EAE had an acute progressive paralytic disease with inflammation and myelin loss detected in the spinal cord. Eighty-six percent (12/14) of mice followed for more than 2 weeks had 1 or more relapses of EAE. These results demonstrate that clinical remission and relapse of EAE can be induced by the single adoptive transfer of a LN-derived BP-specific T cell line in the absence of host-derived effector and regulatory lymphocytes. Furthermore, the data demonstrate that the pathogenic potential of BP-specific T cells is greater in lymphocyte-deficient SCID mice compared with immunocompetent mice, suggesting that autoreactive T cells are controlled by potent inhibitory mechanisms associated with regulatory lymphocytes. These results are relevant to mechanisms of disease remission and relapse mediated by lymphocytes involved in paralytic inflammatory diseases such as multiple sclerosis (MS).

Neutrophils secreting tumor necrosis factor alpha infiltrate the central nervous system of BALB/c mice with experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) can be induced in resistant BALB/c mice by ultrasound-formed adjuvant emulsion. In contrast to susceptible mouse strains large numbers of neutrophils secreting TNF-alpha occupied the central nervous system (CNS) of BALB/c mice with severe EAE, whereas only small numbers of macrophages and CD4+ T-cells could be detected. CNS infiltration was preceded with activation of microglial cells. Ultrasound formed adjuvant induced early IFN-gamma expression in popliteal lymph nodes of BALB/c mice, whereas conventional adjuvant induced delayed IFN-gamma production. Although the clinical outcome of EAE was similar to that seen in susceptible mice, the pathogenesis was distinct having possible implications on the different forms seen in multiple sclerosis.

Mutational analysis of the virus and monoclonal antibody binding sites in MHVR, the cellular receptor of the murine coronavirus mouse hepatitis virus strain A59

The primary cellular receptor for mouse hepatitis virus (MHV), a murine coronavirus, is MHVR (also referred to as Bgp1a or C-CAM), a transmembrane glycoprotein with four immunoglobulin-like domains in the murine biliary glycoprotein (Bgp) subfamily of the carcinoembryonic antigen (CEA) family. Other murine glycoproteins in the Bgp subfamily, including Bgp1b and Bgp2, also can serve as MHV receptors when transfected into MHV-resistant cells. Previous studies have shown that the 108-amino-acid N-terminal domain of MHVR is essential for virus receptor activity and is the binding site for monoclonal antibody (MAb) CC1, an antireceptor MAb that blocks MHV infection in vivo and in vitro. To further elucidate the regions of MHVR required for virus receptor activity and MAb CC1 binding, we constructed chimeras between MHVR and other members of the CEA family and tested them for MHV strain A59 (MHV-A59) receptor activity and MAb CC1 binding activity. In addition, we used site-directed mutagenesis to introduce selected amino acid changes into the N-terminal domains of MHVR and these chimeras and tested the abilities of these mutant glycoproteins to bind MAb CC1 and to function as MHV receptors. Several recombinant glycoproteins exhibited virus receptor activity but did not bind MAb CC1, indicating that the virus and MAb binding sites on the N-terminal domain of MHVR are not identical. Analysis of the recombinant glycoproteins showed that a short region of MHVR, between amino acids 34 and 52, is critical for MHV-A59 receptor activity. Additional regions of the N-terminal variable domain and the constant domains, however, greatly affected receptor activity. Thus, the molecular context in which the amino acids critical for MHV-A59 receptor activity are found profoundly influences the virus receptor activity of the glycoprotein.

Physical state of the neuroantigen in adjuvant emulsions determines encephalitogenic status in the BALB/c mouse

A novel form of adjuvant-neuroantigen formulation was established which was highly encephalitogenic in previously resistant BALB/c mice. The antigen formulation contained mouse whole spinal cord homogenate (MSCH), mycobacteria, and mineral oil, identically to the conventional preparation, but emulsification was completed by sonication instead of extrusion. Sonication of MSCH alone did not render a conventionally prepared emulsion encephalitogenic. The novel adjuvant formulation showed reduced water-oil droplet size, and the neuroantigen was located on the surface of the droplets as well as in the intermicellar space, while in the extruded formulation the material was buried in the droplet interior. Mice inoculated with the sonicated emulsion showed strong brain and spinal cord infiltration of lymphoid cells. The sonicated emulsion was highly encephalitogenic in all six BALB/c substrains tested. The results suggest that availability of the neuroantigen is of critical importance for the development of clinical EAE in the BALB/c mouse.

Histamine-induced microvascular leakage in pial venules: differences between the SJL/J and BALB/c inbred strains of mice

The actions of histamine on pial venule leaky site formation were measured intravitally in two inbred strains of mice (BALB/c and SJL/J). Pial venules were visualized using a cranial window microscopy technique, and microvascular leaky site formation was assessed visually using a fluorescein-dextran indicator. SJL/J mice were found to be sensitive to histamine-induced leakage, whereas the BALB/c strain was refractory. Exposure to pertussis toxin enhanced the sensitivity to histamine in the SJL/J strain, but little effect was observed for BALB/c mice. However, the employment of a polymerase chain reaction (PCR) technique for the detection of mRNA for histamine H1 receptor identified receptor-specific message in isolated cerebrovascular endothelium from both strains of mice. The lack of pial responsiveness in the BALB/c mice remains unexplained. Mast cells in the dura mater were found to be more numerous in SJL/J mice than in BALB/c mice. This observation supports previous observations of strain-specific differences in CNS inflammation. The results support the concept that genetically controlled differences in vascular sensitivity and localization of CNS-associated mast cells may play important roles in the generation of vasogenic edema and inflammation in CNS trauma and disease.

Enhancement of histamine-induced vascular leakage by pertussis toxin in SJL/J mice but not BALB/c mice

Pertussis toxin (PTX) from Bordetella pertussis is known to enhance inflammatory responses which involve histamine and serotonin, including cell-mediated delayed-type hypersensitivity reactions. In this study we examined the effects of PTX on histamine-modulated microvascular responses. The actions of histamine on arteriole diameter and post-capillary leaky site formation in the cremaster muscle were measured intra-vitally in two inbred strains of mice (viz. BALB/c and SLJ). In SJL mice the rate and extent of histamine-induced leaky site formation were greatly enhanced (from 8.3 to 21.0 leaky sites per 0.1 cm2) by pre-exposure to PTX. In sharp contrast, PTX did not alter histamine-induced leaky site formation in BALB/c mice. Histamine-mediated dilation in arterioles in both strains of mice were not enhanced by PTX. PTX may enhance the development of inflammatory responses by enhancing histamine-induced leaky site formation of the microvasculature.

T cell receptor V beta gene utilization in myelin basic protein specific clones from CXJ1 recombinant inbred mice

CXJ1 mice are a recombinant inbred strain generated from experimental allergic encephalomyelitis (EAE) resistant BALB/c and EAE susceptible SJL/J progenitors. CXJ1 derive their major histocompatibility complex (MHC) class II and TCR genes from the BALB/c progenitor. However, their susceptibility to EAE is similar to SJL/J. Utilizing myelin basic protein (MBP)-specific CD4+ hybridoma clones and a MBP-specific T cell line (TCL) from CXJ1, we found the predominant T cell receptor (TCR) V beta chain expression to be V beta 8 and V beta 13. Our data support the concept of preferential, but not exclusive, TCR V beta usage in the MBP-specific response which is independent of MHC class II haplotype or immunodominant peptide.

Relative susceptibility of SJL/J and B10.S mice to experimental allergic encephalomyelitis (EAE) is determined by the ability of prethymic cells in bone marrow to develop into EAE effector T cells

SJL/J mice are highly susceptible to actively induced experimental allergic encephalomyelitis (EAE), whereas B10.S mice are resistant. However, both strains share the H-2s haplotype. We have previously shown that the relative susceptibility of SJL/J and B10.S mice to acute EAE correlates, respectively, with high and low responsiveness to myelin basic protein (MBP), as determined by cloning and limiting dilution analysis of in vitro T cell proliferation. Here, we have investigated the ability of SJL/J and B10.S mice to generate EAE-effector T cells in vivo. We have developed a new mouse strain, B10.S Thy 1.1, that differs at the Thy 1 locus from SJL/J and B10.S mice (both Thy 1.2) but has the same MHC and resistance pattern to EAE as do B10.S mice. Using radiation bone marrow chimeras formed between SJL/J and B10.S Thy 1.1 mice, we have shown that a population of radiosensitive prethymic cells in SJL/J bone marrow has an intrinsic potential to generate EAE-effector T cells, whereas that in B10.S Thy 1.1 bone marrow does not. This lack of detectable EAE effector cells in B10.S Thy 1.1 mice does not appear to be due to the generation of suppressor T cells or to a defect in antigen-presenting cells. Moreover, the potential of SJL/J bone marrow to generate EAE-effector T cells is not inhibited by the concomitant presence of B10.S Thy 1.1 bone marrow cells, thymocytes or dendritic cells in mixed chimeras. Hence, the relative susceptibility of SJL/J and B10.S mice to EAE appears to be directly related to the respective responder status of their T cells to MBP, as evidenced by their ability (or inability) to generate EAE-effector T cells. This high and low responder status appears in turn to be linked to non-MHC background genes, although this has not been established formally.

Comparison of CNS homing pattern among murine TH cell lines responsive to myelin basic protein

A myelin basic protein (MBP)-reactive TH cell line capable of inducing experimental allergic encephalomyelitis (EAE), and a MBP-reactive TH cell clone that does not cause EAE were labeled with a fluorescent vital dye, and transferred into naive syngeneic SJL/J mice. Animals were killed before the appearance of symptoms (3 and 4 days post-injection). Sections obtained from the spleen, spinal cord and brain of both groups of animals were examined by fluorescence microscopy to localize labeled TH cells. At all time points examined, the spleens of both groups contained innumerable labeled cells. The spinal cords and brains of animals that had received EAE-causing cells had a basal level of 20 labeled cells/cm2 at 3 days; this number increased rapidly to 150 cells/cm2 in the spinal cord at 4 days. Perivascular infiltrates and small foci of astrogliosis were already apparent in this group 3 days after injection. The spinal cords and brains of animals that had received the non-EAE-causing TH cells contained 50 labeled cells/cm2 at 3 days. The density of these transferred cells, as compared to that of the EAE-causing cells, suggested that they have an unaltered CNS-homing capability. However, by 4 days, the number of non-EAE-causing labeled cells had returned to near basal level. Our findings suggest that discrimination between disease and non-disease causing MBP-responsive TH cells occurs within the first 3 days following transfer, requires the presence in the CNS of a limited number of TH cells, and depends on yet unidentified TH cell factor(s).

Mouse hepatitis virus (MHV-4, JHM) blocks gamma-interferon-induced major histocompatibility complex class II antigen expression on murine cerebral endothelial cells

The regulation of gamma-interferon-induced major histocompatibility complex (MHC) class II antigen expression on mouse cerebral endothelial cells by the neurotropic mouse hepatitis virus (MHV-4, JHM) was studied in vitro. The results presented demonstrate that MHV-4 can selectively block gamma-interferon-induced class II antigen expression on cerebral endothelial cells. The blocking effect of class II expression occurs in a strain-dependent manner, and is limited to virus-susceptible mouse strains. Virus replication is not required to obtain the blocking effect since UV-inactivated MHV-4 produces the same result. MHV-4 blocking of gamma-interferon-induced class II antigen expression is observed at both the cell surface (flow cytometry) and transcriptional level (Northern analysis).

Receptor for mouse hepatitis virus is a member of the carcinoembryonic antigen family of glycoproteins

The receptor for mouse hepatitis virus (MHV), a murine coronavirus, is a 110- to 120-kDa glycoprotein on intestinal brush border membranes and hepatocyte membranes. The N-terminal 25-amino acid sequence of immunoaffinity-purified MHV receptor was identical to the predicted mature N termini of two mouse genes related to human carcinoembryonic antigen (CEA) and was strongly homologous to the N termini of members of the CEA family in humans and rats. Polyclonal antibodies to human CEA recognized the immunoaffinity-purified MHV receptor and the MHV receptor in liver membranes and intestinal brush border membranes from MHV-susceptible mouse strains. In membranes from MHV-resistant SJL/J mice, the anti-CEA antibodies recognized a homologous glycoprotein that failed to bind MHV. The MHV receptor glycoprotein was detected in membranes of BALB/c colon, small intestine, and liver, which are the principal targets for MHV replication in vivo. The MHV receptor glycoprotein resembled members of the human CEA family in molecular weight, acidic pI, extensive glycosylation, solubility in perchloric acid, and tissue distribution. Thus, the MHV receptor is, to our knowledge, the first member of the CEA family of glycoproteins to be identified as a virus receptor.

Purification of the 110-kilodalton glycoprotein receptor for mouse hepatitis virus (MHV)-A59 from mouse liver and identification of a nonfunctional, homologous protein in MHV-resistant SJL/J mice

The receptor for mouse hepatitis virus strain A59 (MHV-A59) is a 110- to 120-kilodalton (kDa) glycoprotein which is expressed in MHV-susceptible mouse strains on the membranes of hepatocytes, intestinal epithelial cells, and macrophages. SJL/J mice, which are highly resistant to MHV-A59, were previously shown to lack detectable levels of receptor by using either solid-phase virus receptor assays or binding of a monoclonal anti-receptor antibody (MAb) which blocks infection of MHV-susceptible mouse cells. This MAb was used for affinity purification of the receptor glycoprotein from livers of MHV-susceptible Swiss Webster mice. The MHV receptor and an antigenically related protein of 48 to 58 kDa were copurified and then separated by preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The first 15 amino acids of the receptor were sequenced, and a synthetic peptide of this amino acid sequence was prepared. Rabbit antiserum made against this peptide bound to the MHV receptor glycoprotein and the 48- to 58-kDa protein from livers of MHV-susceptible BALB/c mice and Swiss Webster mice and from the intestinal brush border of BALB/c mice. In immunoblots of intestinal brush border and hepatocyte membranes of MHV-resistant SJL/J mice, the antibody against the amino terminus of the receptor identified proteins that are 5 to 10 kDa smaller than the MHV receptor and the 48- to 58-kDa related protein from Swiss Webster or BALB/c mice. Thus, SJL/J mice express a protein which shares some sequence homology with the MHV receptor but which lacks virus-binding activity and is not recognized by the blocking anti-receptor MAb. These results suggest that resistance of SJL/J mice to MHV-A59 may be due to absence or mutation of the virus-binding domain in the nonfunctional receptor homolog in SJL/J mice.

Genetic regulation of class I major histocompatibility complex (MHC) antigen induction on astrocytes

Neural cells, including astrocytes, normally do not express detectable levels of class I major histocompatibility complex (MHC) molecules, unlike cells of most tissues. However, upon cultivation in vitro, astrocytes begin to express class I molecules, increasing with time after plating. This spontaneous expression was examined in the present study to characterize inducible expression on astrocytes among various strains of mice. Inducible expression, either as a consequence of cultivation or standard gamma-interferon treatment, differed markedly among the strains examined. Analysis of congenic strains on a C57BL/10 (B10) background showed that expression was controlled by genes within the MHC locus. Examination of additional congeneic animals with various recombinations within the MHC showed that high or low expression of MHC molecules correlates with the presence of particular MHC class I genes. In general, H-2a and H-2d class I products are expressed much higher on astrocytes than H-2b and H-2s products. This difference in expression is not seen on spleen cells indicating tissue specificity. Moreover, levels of expression at the cell surface are reflected by the steady-state level of RNA message within astrocytes of the different strains.

Differential modulation of MHC class I antigen expression on mouse brain endothelial cells by MHV-4 infection

Virus-induced modulation of mouse cerebral endothelial cell class I and class II antigens by the neurotropic coronavirus, MHV-4 (JHM), was examined by flow cytometry. In susceptible BALB/c, H-2Kd was downregulated, while H-2Dd was upregulated following infection by MHV-4. In contrast, H-2K and H-2D antigens were both upregulated in either MHV-4-susceptible B10.S and (BALB/c x SJL) F1, or MHV-4-resistant SJL-derived cerebral endothelial cells following infection with this virus. Class II antigen expression was unchanged following MHV-4 infection. Virus-induced MHC class I modulation is genetically regulated, and may influence virus clearance by class I-dependent CTL.

Modulation of resistance to Salmonella typhimurium infection in mice by mouse hepatitis virus (MHV)

Prior infection of mice with a field strain of mouse hepatitis virus (MHV) increased the early resistance of euthymic mice to virulent Salmonella typhimurium strain SR-11 infections (as defined by significantly fewer salmonella colony-forming units (cfu) present in spleens and livers 4 days after salmonella infection). This increase in salmonella resistance was observed when the interval between MHV and salmonella infections was 6 days, but not at 3, 10, or 14 day intervals. The mouse Ity locus, which controls the number of intracellular salmonella, had a significant effect on the ability of MHV to induce resistance to salmonella. MHV caused an increase in resistance to salmonella in Itys (salmonella susceptible) mice at all doses of salmonella tested (100 to 10,000 cfu). In the Ityr (salmonella resistant) mice tested the beneficial effect of MHV on salmonella resistance was small and when observed, was only present at salmonella doses of 10,000 cfu or greater. Neither the Lpsd nor Xid mutations affected the ability of MHV to increase resistance to salmonella infection. In contrast to euthymic mice, MHV infection greatly decreased the resistance of athymic (nude) mice to salmonella infection. Since the Nu locus does not affect the resistance of mice to salmonella (at 4 days post salmonella infection), these results indicate that MHV infection and the nude phenotype interact to increase susceptibility to salmonella. These findings re-emphasize the importance of keeping laboratory mice used in research free of MHV and other immunomodulatory pathogens.

T cell receptor beta chain gene rearrangement shared by murine T cell lines derived from a site of autoimmune inflammation

Advances in our understanding of the structure and molecular biology of the T lymphocyte antigen-receptor have now made it feasible to study human autoimmune diseases using new approaches. One such approach involves cloning of T cells from sites of autoimmune pathology followed by identification of putative disease-related T cell oligoclonality at the level of the T cell receptor gene rearrangements. We have now tested the feasibility of this approach in an animal model of autoimmunity, murine experimental allergic encephalomyelitis (EAE). Spinal cord-derived, self (murine) myelin basic protein (MBP)-reactive T cell lines and sublines were analyzed at the level of their receptor beta chain rearrangements using Southern blots. We now report that the MBP-reactive T cell lines and sublines derived from the spinal cords of four of five SJL/J mice with EAE share a 14.5-kb rearranged T cell receptor beta 1 band on Southern blots. A spinal cord-derived T cell line that was reactive to purified protein derivative of tuberculin (PPD), several lymph node-derived ovalbumin- and PPD-reactive T cell lines, as well as one MBP-reactive spinal cord-derived T cell line did not share this 14.5-kb rearranged beta 1 band. These results suggest that analysis of the antigen receptors used by T cells cloned from sites of inflammation may be a useful initial approach for identifying pathogenetically relevant T cells in the study of certain human autoimmune diseases.

Heterotopic brain transplants in the study of experimental allergic encephalomyelitis

A heterotopic transplant paradigm was developed for its potential usefulness in dissecting genetically determined immune and central nervous system (CNS) components in the induction of experimental allergic encephalomyelitis (EAE). EAE is a cell-mediated, organ-specific, autoimmune disease producing inflammatory demyelination in the CNS. Susceptibility to EAE is determined by multiple genes and reflects both immune competence and target tissue responses. Syngeneic fetal CNS was heterotopically transplanted into the anterior chamber of the eye or beneath the capsule of the kidney of adult SJL or (SJL X BALB/c)F1 mice. Transplants usually survived better in the eye than the kidney. Six to eight weeks after transplantation, some mice were immunized for EAE. Immunized mice developed clinical and pathological signs of EAE in 12 to 15 days. The placement of CNS tissue into the eye or kidney prior to immunization did not suppress induction of EAE. Transplants in either location, in immunized mice, manifested perivascular inflammation and demyelination similar to that seen in the host CNS. However, transplants in mice not immunized for EAE, but maintained an equal time period after transplantation, did not demonstrate these features. The ability to produce the specific pathologic lesions of EAE in CNS tissue transplanted outside the CNS allows the design of studies of the tissue localization of genetic restrictions to development of EAE.

The Theiler's murine encephalomyelitis virus (TMEV) model for multiple sclerosis shows a strong influence of the murine equivalents of HLA-A, B, and C

Following intracerebral inoculation of Theiler's murine encephalomyelitis virus (TMEV), susceptible mouse strains develop a chronic demyelinating disease characterized histologically by mononuclear cell-rich infiltrates in the central nervous system (CNS). An immune-mediated basis for this disease is strongly supported by previous studies demonstrating a correlation between clinical disease susceptibility, the presence of particular H-2 region genotypes, and the development of chronically elevated levels of TMEV-specific, MHC class II-restricted delayed-type hypersensitivity (DTH). The present study compared disease susceptibility in (B10.S X SJL)F1 and (B10.S(26R) X SJL)F1 mice which differ only at the D region of the H-2 complex. The data conclusively demonstrates a major influence for homozygosity of H-2s alleles at the H-2D region (the murine equivalent of the human class I HLA-A, B, and C genes) in determining disease susceptibility, as measured by either clinical or histopathological endpoints. In addition, disease susceptibility strongly correlated with the development of high levels of TMEV-specific DTH in the susceptible (B10.S X SJL)F1 strain. However, disease susceptibility did not appear to correlate with TMEV titers in the CNS, TMEV-specific humoral (ELISA and neutralizing) immune responses, or virus-specific splenic T cell proliferative responses. These findings lend additional support to our hypothesis that CNS myelin damage is mediated by a TMEV-specific DTH response. The possible role of class I-restricted responses in the demyelinating process is discussed and murine TMEV-induced demyelinating disease is compared with experimental allergic encephalomyelitis as relevant animal models for human multiple sclerosis.

Hyperinducibility of Ia antigen on astrocytes correlates with strain-specific susceptibility to experimental autoimmune encephalomyelitis

In search of a phenotypic marker determining genetically controlled susceptibility to delayed-type hypersensitivity (DTH) reactions in the brain--in particular, experimental autoimmune encephalomyelitis (EAE)--we have compared the gamma-interferon (IFN-gamma) induction of Ia molecules on astrocytes and macrophages from rat and mouse strains that are susceptible or resistant to this disease. We focused on Ia expression because DTH reactions to self or foreign antigens are largely mediated by lymphocytes restricted by class II (Ia) antigens of the major histocompatibility complex (MHC). Our data demonstrate that Lewis (fully susceptible) and Brown Norway (BN) (fully resistant) rats are very different in that Lewis astrocytes express much higher levels of Ia than BN astrocytes. Similar data were obtained from an analysis of EAE-susceptible and -resistant mouse strains (SJL and BALB/c, respectively), which suggests that this phenomenon may be universal and not limited to only one mammalian species. At least one gene responsible for Ia hyperinduction is located outside the rat RT-1 or the mouse MHC locus. Animals congenic at the RT-1 or MHC locus of the resistant strain but with background genes of the susceptible strain exhibit intermediate levels of Ia compared to fully resistant and susceptible rodents, which fits well with the reduced EAE susceptibility of these congenic animals. Furthermore, hyperinduction of Ia is astrocyte specific, since peritoneal macrophages of susceptible and resistant strains exhibit identical profiles of Ia induction. Thus, astrocyte Ia hyperinducibility may be a major strain- and tissue-specific factor that contributes to Ia-restricted DTH reactions in the brain.

Adoptive transfer of murine chronic-relapsing autoimmune encephalomyelitis. Analysis of basic protein-reactive cells in lymphoid organs and nervous system of donor and recipient animals

Frequency analysis of myelin basic protein (MBP)-reactive lymphocytes was performed in the chronic relapsing murine experimental allergic encephalomyelitis (EAE) model induced by the adoptive transfer of myelin basic protein (MBP)-primed lymphocytes to naive recipients. During the first attack, MBP-reactive cell frequencies were: 1/41,700 in spleen, 1/328,000 in lymph nodes, 1/64,500 in the peripheral blood. After recovery from a second attack, the frequencies were: 1/11,000 in spleen, 1/46,000 in lymph node, and 1/195,000 in the blood. In addition, lymph node cells obtained from animals following a second attack had increased encephalitogenic properties. CNS-derived lymphocytes analyzed during the first attack were 50% Lyt 1.2+ and 16% Lyt 2.2+. After recovery from the second attack, phenotypes were 20% Lyt 1.2+ and 49% Lyt 2.2+. There were only minimal responses to MBP in CNS-derived lymphocytes. Susceptibility to adoptively transferred EAE was in general predicted by whether a proliferative response to MBP occurred following immunization and was not solely H-2 linked. These studies demonstrate an accumulation of autoreactive cells in the spleen and lymph nodes and a shift of the phenotype of cells in the target organ as EAE becomes chronic and suggest there are dynamic immunologic processes, both in the peripheral immune system and target organ associated with relapsing EAE.

Relapsing experimental allergic encephalomyelitis in radiation bone marrow chimeras between high and low susceptible strains of mice

The relapsing form of experimental allergic encephalomyelitis (EAE) has been shown to be a useful model of the human disease, multiple sclerosis. This autoimmune disease is organ specific and appears to be primarily a cell-mediated disorder similar to the acute form of EAE. In order to understand better the regulatory mechanisms responsible for development of disease, radiation bone marrow chimeras were prepared between the highly susceptible SJL/J mouse and the resistant B10.S mouse. A high incidence of disease was seen in SJL----SJL and B10.S----SJL chimeras. A low incidence was seen in B10.S----B10.S and SJL----B10.S chimeras. The results were similar in mice immunized with CNS antigen of either BALB/c or B10.S origin. These results demonstrate that the immune system from the resistant B10.S mouse is capable of mediating relapsing EAE when present in a susceptible SJL host, while the SJL immune system was restricted in its ability to induce disease when present in a resistant B10.S host. This would indicate that restriction to the development of EAE may reside outside of the immune system, perhaps involving antigen recognition or presentation in the CNS itself.

Acute experimental allergic encephalomyelitis in radiation bone marrow chimeras between high and low susceptible strains of mice

Acute experimental allergic encephalomyelitis (EAE) is an autoimmune disease involving the central nervous system (CNS) that can be elicited in susceptible strains of mice by the subcutaneous inoculation of mouse spinal cord homogenate (MSCH) in conjunction with complete Freund's adjuvant. In order to localize the physiological compartment conveying susceptibility to mice for EAE induction, hematopoietic radiation chimeras were prepared between the highly responsive SJL and low responder B10.S strains. Upon challenge with SJL MSCH preparations, high incidence of clinical disease was exhibited by B10.S----SJL chimeras but not by SJL----B10.S mice, suggesting that non-bone-marrow-derived factors were influencing development of disease. The incidence of histological lesions in the CNS was high for virtually all experimental and control groups except normal B10.S and B10.S----B10.S reconstituted mice. In contrast, challenge with B10.S MSCH induced a high clinical incidence of EAE in both B10.S----SJL and SJL----B10.S chimeras, indicating a possible interstrain difference in the immunogenicity of relevant CNS antigens.