CD4+ T Cells Reactive to Enteric Bacterial Antigens in Spontaneously Colitic C3H/HeJBir Mice: Increased T Helper Cell Type 1 Response and Ability to Transfer Disease

C3H/HeJBir mice are a new substrain that spontaneously develop colitis early in life. This study was done to determine the T cell reactivity of C3H/HeJBir mice to candidate antigens that might be involved in their disease. C3H/HeJBir CD4+ T cells were strongly reactive to antigens of the enteric bacterial flora, but not to epithelial or food antigens. The stimulatory material in the enteric bacteria was trypsin sensitive and restricted by class II major histocompatibility complex molecules, but did not have the properties of a superantigen. The precursor frequency of interleuken (IL)-2–producing, bacterial-reactive CD4+ T cells in colitic mice was 1 out of 2,000 compared to 1 out of 20,000–25,000 in noncolitic control mice. These T cells produced predominately IL-2 and interferon γ, consistent with a T helper type 1 cell response and were present at 3–4 wk, the age of onset of the colitis. Adoptive transfer of bacterial-antigen–activated CD4+ T cells from colitic C3H/HeJBir but not from control C3H/HeJ mice into C3H/HeSnJ scid/scid recipients induced colitis. These data represent a direct demonstration that T cells reactive with conventional antigens of the enteric bacterial flora can mediate chronic inflammatory bowel disease

Mutations in a NIMA-related kinase gene, Nek1, cause pleiotropic effects including a progressive polycystic kidney disease in mice

We previously have described a mouse model for polycystic kidney disease (PKD) caused by either of two mutations, kat or kat(2J), that map to the same locus on chromosome 8. The homozygous mutant animals have a latent onset, slowly progressing form of PKD with renal pathology similar to the human autosomal-dominant PKD. In addition, the mutant animals show pleiotropic effects that include facial dysmorphism, dwarfing, male sterility, anemia, and cystic choroid plexus. We previously fine-mapped the kat(2J) mutation to a genetic distance of 0.28 ± 0.12 centimorgan between D8Mit128 and D8Mit129. To identify the underlying molecular defect in this locus, we constructed an integrated genetic and physical map of the critical region surrounding the kat(2J) mutation. Cloning and expression analysis of the transcribed sequences from this region identified Nek1, a NIMA (never in mitosis A)-related kinase as a candidate gene. Further analysis of the Nek1 gene from both kat/kat and kat(2J)/kat(2J) mutant animals identified a partial internal deletion and a single-base insertion as the molecular basis for these mutations. The complex pleiotropic phenotypes seen in the homozygous mutant animals suggest that the NEK1 protein participates in different signaling pathways to regulate diverse cellular processes. Our findings identify a previously unsuspected role for Nek1 in the kidney and open a new avenue for studying cystogenesis and identifying possible modes of therapy

Characterization of Simian Virus 40 tsA 58 Transcriptional Intermediates at Restrictive Temperatures: Relationship Between DNA Replication and Transcription

When nuclei from simian virus 40 (SV40)-infected cells are lysed with Sarkosyl and the chromatin is pelleted, the supernatant fluid contains a nucleoprotein complex capable of synthesizing viral RNA (Laub and Aloni, Virology 75:346-354, 1976; Gariglio and Mousset, FEBS Lett. 56:149-155, 1975). The level of activity of the RNA polymerase in the complex increased during infection in parallel with the amount of viral DNA that had been synthesized. If cells infected at 33°C with the SV40 mutant tsA 58 were shifted to the nonpermissive temperature of 40°C at any time between 18 and 48 h postinfection, no viral DNA replication was detected after 45 min and no new rounds of synthesis were initiated after 20 to 30 min. However, after this shift, polymerase activity associated with the nucleo-protein complex did continue to increase for 5 h, at which time it reached a plateau. There was an increase of RNA synthesized from both the early (E) and late (L) SV40 DNA strands, and there was a threefold increase in the ratio of early-to-late RNA species after the shift. In comparable experiments with cells infected with wild-type virions, no increase in polymerase activity occurred because of the temperature change alone. At 33°C, the relative amount of RNA transcribed from the wild-type E-strand was less than tsA 58 at 33°C and did not increase after a shift to 40°C. The tsA 58 transcriptional complexes extracted from cells grown at 33°C sedimented heterogeneously in sucrose gradients, with a peak near 26S. There were no detectable alterations in the sedimentation properties of the complexes when tsA 58-infected cells were shifted to 40°C for 2 h. We conclude that continued synthesis of viral DNA is not an obligatory prerequisite for maintenance of late viral transcription nor is the sedimentation of the transcriptional complex at 26S related to actively replicating DNA molecules serving as templates for transcription. Further, an increase in late transcription can occur under conditions where reinitiation of viral DNA synthesis is prevented. The increase in the synthesis of early and late RNA at the restrictive temperature without concurrent DNA synthesis is discussed in relationship to the function of the A gene product

Differential susceptibility of inbred mouse strains to dextran sulfate sodium-induced colitis

Dextran sulfate sodium (DSS)-induced murine colitis represents an experimental model for human inflammatory bowel disease. The aim of this study was to screen various inbred strains of mice for genetically determined differences in susceptibility to DSS-induced colitis. Mice of strains C3H/HeJ, C3H/HeJBir, C57BL/6J, DBA/2J, NOD/LtJ, NOD/LtSz-Prkdc(scid)/Prkdc(scid), 129/SvPas, NON/LtJ, and NON.NOD-H2g7 were fed 3.5% DSS in drinking water for 5 days and necropsied 16 days later. Ceca and colons were scored for histological lesions based on severity, ulceration, hyperplasia, and area involved. Image analysis was used to quantitate the proportion of cecum ulcerated. Histological examination revealed significant differences among inbred strains for all parameters scored. In both cecum and colon, C3H/HeJ and a recently selected substrain, C3H/HeJBir, were highly DSS susceptible. NOD/LtJ, an autoimmune-prone strain, and NOD/LtSz-Prkdc(scid)/Prkdc(scid), a stock with multiple defects in innate and adoptive immunity, were also highly DSS susceptible. NON/LtJ, a strain closely related to NOD, was quite DSS resistant. The major histocompatibility (MHC) haplotype of NOD mice (H2g7), a major component of the NOD autoimmune susceptibility, was not crucial in determining DSS susceptibility, since NON mice congenic for this MHC haplotype retained resistance. C57BL/6J, 129/SvPas, and DBA/2J mice showed various degrees of susceptibility, depending upon the anatomical site. A greater male susceptibility to DSS-induced colonic but not cecal lesions was observed. In summary, this study demonstrates major differences in genetic susceptibility to DSS-induced colitis among inbred strains of mice. Knowledge of these strain differences in genetic responsiveness to acute inflammatory stress in the large intestine will permit design of genetic crosses to elucidate the genes involved