A role for IL-1 alpha in inducing pathologic inflammation during bacterial infection.

Infection with pathogenic microbes often results in a significant inflammatory response. A cascade of proinflammatory cytokines including tumor necrosis factor alpha (TNF-alpha) and IL-1 initiates this response. Although there is a clear role for IL-1 during infection, little is known to distinguish the role of IL-1 alpha from that of IL-1 beta during this process. With the use of Yersinia enterocolitica as a model enteric pathogen, we have identified a specific role for IL-1 alpha in inducing pathologic inflammation during bacterial infection. Depletion of IL-1 alpha in mice infected with wild-type Y. enterocolitica results in significantly decreased intestinal inflammation. Furthermore, a bacterial mutant that does not induce IL-1 alpha expression but induces normal levels of IL-1 beta, TNF-alpha, and IFN-gamma, causes greatly reduced intestinal inflammation and is attenuated by LD(50) analysis in the C57BL/6 mouse model. These results demonstrate a distinct and unrecognized role for IL-1 alpha in inducing intestinal inflammation that cannot be compensated for by the endogenous levels of IL-1 beta, TNF-alpha, or IFN-gamma that are produced in response to Y. enterocolitica. Additionally, these results suggest that IL-1 alpha-induced inflammation is a major contributor to the pathology of yersiniosis.

Osteogenic protein-1 mRNA expression is selectively modulated after acute ischemic renal injury.

Osteogenic protein-1 (OP-1) is a morphogenetic factor highly expressed in the kidney and involved in tissue repair and development. Homozygous OP-1-deficient mice die shortly after birth due mainly to arrest of renal growth and differentiation. Because postischemic injury involves several repair mechanisms, this study examined whether kidney OP-1 mRNA expression is modulated after ischemia. Acute ischemic renal injury was achieved in rats by unilateral clamping of the renal pedicle followed by reperfusion. Rats were killed at 3, 6, 12, 24, and 48 h and 7 d after reperfusion, and kidneys were microdissected and analyzed by histology and Northern and Western blots. Changes in OP-1 mRNA were determined by measuring the ratio of OP-1/glyceraldehyde 3-phosphate dehydrogenase signals for each OP-1 transcript (4.0 and 2.4 kb) from ischemic, opposite, and sham-operated rats. The OP-1 mRNA content for transcript 4.0 kb was fivefold lower in the whole ischemic kidney compared with that in sham animals 24 h after reperfusion. In the ischemic medulla, OP-1 mRNA was strikingly downregulated 20-fold when compared with the ischemic cortex. Results for transcript 2.4 kb and for the other time points were comparable. OP-1 mRNA expression was also affected in the opposite medulla compared with the sham medulla. However, only in the ischemic medulla was the relative OP-1 content significantly lower at all time points. Similar results were obtained when analyzing OP-1 protein by Western blot at 24 h after reperfusion. Seven days after reperfusion, the levels of OP-1 mRNA returned to baseline. In conclusion, kidney OP-1 mRNA and protein are selectively downregulated in the medulla after acute ischemic renal injury. OP-1 modulation may be a key element for kidney repair.

Differential expression of conglycinin α' and ß subunit genes in transgenic plants.

ß-conglycinin or 7S protein, one of the two major storage proteins of soybean (Glycine max), is comprised of three subunits, α', α and ß. Genomic clones encoding the α' and ß subunit genes were ligated together in intermediate plasmids, either in direct orientation (← ←) or in divergent orientation (← →). In the latter instance the transcriptional promoters of the two genes were approximately 2.0 kb apart. The DNAs were introduced into leaf disks of Petunia hybrida on a disarmed Ti plasmid in Agrobacterium tumefaciens and transgenic plants were regenerated. Expression of the introduced genes, limited to specific stages in developing seeds, was analyzed by quantitating the accumulated mRNA and protein, and compared with expression in transgenic plants that contained either gene alone. Development time course studies showed that the α' subunit mRNA and protein were first detected at 10 days after pollination while accumulation of the ß subunit protein ensued at day 14 regardless of the orientation of the two genes. The temporally regulated expression of these two genes in transgenic plants mimics their temporal regulation during soybean embryo development. In transgenic plants that contain the α' and ß genes in divergent orientation, expression of the ß gene was enhanced several-fold, while the expression of the α' gene was slightly decreased. These results suggest that (i) sequences of the α' gene enhance the level of expression of a nearby storage protein gene and that (ii) the signal(s) operating in the temporal regulation of seed storage protein genes is (are) common to soybean and petunia, and are different from those that govern the final amounts of mRNA and protein.