Abstract
Unmethylated CpG dinucleotides in bacterial DNA stimulate mammalian dendritic cells to support T-helper type-1 (Th1) cell development. These dinucleotides are important inducers of innate immunity and can serve as valuable adjuvants for vaccination. An international group of researchers recently showed that homozygous knockout mice lacking TLR9, a member of the Toll-like receptor family, were resistant to CpG-induced cytokine release and subsequent development of shock. Furthermore, TLR9-/- mice did not mount a CpG-induced Th1-like response. These findings suggest that TRL9 plays an important role in mediating the effects of CpG dinucleotides on the immune system.
Hammi H, Takeuchi O, Kawal T, Kaisho T, Sato S, Sanjo H, Matsumo M, Hoshino K, Wagner H, Takeda K, Akira S: A Toll-like receptor recognizes bacterial DNA. Nature 408 740–745, 2000.
Laser capture microdissection (LCM) is a valuable tool for the isolation of specific cell types from complex tissues and subsequent mRNA characterization of cell subpopulations. To enhance cell type identification for LCM, a group of German scientists developed optimized immunohistochemical staining techniques that improved mRNA recovery following LCM. Their techniques employed indirect immunofluorescence on frozen tissue sections. Messenger RNA preservation was enhanced by mild fixation and short incubation times with the primary antibody.
Fink L, Kinfe T, Seeger W, Ermert L, Kumer W, Bohle RM: Immunostaining for cell picking and real-time mRNA quantitation. Am J Pathol 157:1459–1466, 2000.
A group of Japanese investigators demonstrated directly that inflammation promotes neoplastic progression. They transplanted a non-tumorigenic human cell line derived from a colonic polyp subcutaneously into nude mice. Transplanted cells were free or attached to plastic plates that induced inflammation; free cells were injected into non-inflamed areas or into sites of chronic inflammation from which plastic plates had been removed. Tumors arose only from cells attached to plates or injected into sites of plate-induced chronic inflammation, and the tumor cells maintained their tumorigenicity when transplanted into new hosts. Fibroblasts from plastic-associated sites of inflammation produced soluble factor(s) that stimulated the growth of non-tumorigenic cells.
Okada F, Kawaguchi T, Habelhah H, Kobayashi T, Tazawa H, Takeichi N, Kitagawa T, Hosokawa M: Conversion of human colonic adenoma cells to adenocarcinoma cells thorugh inflammation in nude mice. Lab Invest 80:1617–1628, 2000.
Visceral leishmaniasis in dogs in the United States is uncommon. However, the disease is endemic in Oklahoma, Texas, and Ohio, and there has been a recent outbreak of the disease in Foxhounds on the East Coast. In one recent case of the disease, a dog from Maryland showed clinical signs including wasting, lethargy, lymphadenopathy, hepatomegaly, splenomegaly, joint stiffness, and skin fragility. Nonregenerative anemia, neutropenia, lymphopenia, and monoclonal gammopathy were present. Parasites were seen in bone marrow and the diagnosis was confirmed by serology. A sand-fly vector can transmit the disease from dogs to man, thus there is concern that visceral leishmaniasis in dogs poses a potential threat to the human population.
Eddlestone SM: Visceral leishmaniasis in a dog from Maryland. J Am Vet Med Assoc 217:1686–1688, 2000.
Gene therapy techniques continue to improve, as indicated by a recent report from United States investigators studying muscular dystrophy in the mdx mouse model. They inserted truncated dystrophin genes less than 4.2 kb long into adenoassociated viral vectors under the control of the muscle-specific creatine kinase promoter and injected these constructs in the muscles of mdx mice. This resulted in efficient and stable dystrophin expression and restoration of normal myo-fiber morphology.
Wang B, Li J, Xiao X: Adeno-associated virus vector carrying human minidystrophin genes effectively ameliorates muscular dystrophy in mdx mouse model. Proc Natl Acad Sci USA 97:13714–13719, 2000.