Lymphocytic infiltrates and lymphoid follicles with germinal centers are often detected in autoimmune thyroid disease (AITD), but the mechanisms underlying lymphocyte entry and organization in the thyroid remain unknown. We tested the hypothesis that CCL21, a chemokine that regulates homeostatic lymphocyte trafficking, and whose expression has been detected in AITD, is involved in the migration of lymphocytes to the thyroid. We show that transgenic mice expressing CCL21 from the thyroglobulin promoter (TGCCL21 mice) have significant lymphocytic infiltrates, which are topologically segregated into B and T cell areas. Although high endothelial venules expressing peripheral lymph node addressin were frequently observed in the thyroid tissue, lymphocyte recruitment was independent of L-selectin or lymphotoxin-α but required CCR7 expression. Taken together, these results indicate that CCL21 is sufficient to drive lymphocyte recruitment to the thyroid, suggest that CCL21 is involved in AITD pathogenesis, and establish TGCCL21 transgenic mice as a novel model to study the formation and function of lymphoid follicles in the thyroid.

The paramyxovirus nucleoproteins (NPs) encapsidate the genomic RNA into nucleocapsids, which are then incorporated into virus particles. We determined the protein-protein interaction between NP molecules and the molecular mechanism required for incorporating nucleocapsids into virions in two closely related viruses, human parainfluenza virus type 1 (hPIV1) and Sendai virus (SV). Expression of NP from cDNA resulted in in vivo nucleocapsid formation. Electron micrographs showed no significant difference in the morphological appearance of viral nucleocapsids obtained from lysates of transfected cells expressing SV or hPIVI NP cDNA. Coexpression of NP cDNAs from both viruses resulted in the formation of nucleocapsid composed of a mixture of NP molecules; thus, the NPs of both viruses contained regions that allowed the formation of mixed nucleocapsid. Mixed nucleocapsids were also detected in cells infected with SV and transfected with hPIV1 NP cDNA. However, when NP of SV was donated by infected virus and hPIV1 NP was from transfected cDNA, nucleocapsids composed of NPs solely from SV or solely from hPIVI were also detected. Although almost equal amounts of NP of the two viruses were found in the cytoplasm of cells infected with SV and transfected with hPIV1 NP cDNA, 90% of the NPs in the nucleocapsids of the progeny SV virions were from SV. Thus, nucleocapsids containing heterologous hPIV1 NPs were excluded during the assembly of progeny SV virions. Coexpression of hPIV1 NP and hPIV1 matrix protein (M) in SV-infected cells increased the uptake of nucleocapsids containing hPIV1 NP; thus, M appears to be responsible for the specific incorporation of the nucleocapsid into virions. Using SV-hPIV1 chimera NP cDNAs, we found that the C-terminal domain of the NP protein (amino acids 420 to 466) is responsible for the interaction with M.Parainfluenza viruses, members of the Respirovirus genus of the Paramyxovidae family, consist of a lipid envelope enclosing a helical nucleocapsid that contains the nonsegmented single negative-stranded RNA genome. This genome is approximately 15,500 nucleotides in length and encodes at least seven structural proteins: the nucleocapsid (NP), phospho-(P/C), large (L) polymerase, matrix (M), hemagglutinin-neuraminidase (HN), and fusion (F) proteins (6). The viral genome is tightly associated with NP to form an RNase-resistant helical nucleocapsid (11). The nucleocapsid is the template for transcription and replication of the genome (16). When paramyxovirus NPs are expressed from cDNAs, they alone form the nucleocapsid-like structures, without other viral proteins or RNA (4,12,13,26). Studies using deletion mutants and protease-cleaved NPs suggest that the domains required for NP-NP and NP-RNA interactions reside in the 410 N-terminal amino acids of NP (4,8,20).Although some aspects of the paramyxovirus assembly are now understood, the precise molecular interactions by which the virus particle is assembled at the plasma membrane remain unknown. The working model for the assembly of the virus c...

Invasive aspergillosis is a common and devastating pneumonia in immunocompromised hosts. Neutrophils are critical for defense against this infection, and ELR+ CXC chemokines are potent neutrophil chemoattractants. We hypothesized that transient lung-specific overexpression of one such ligand, KC, in mice with invasive aspergillosis improves the outcome of disease. We generated mice in which transgenic expression of KC was limited to the lungs and occurred only upon exposure to tetracycline analogues, and we exposed them to doxycycline after the onset of invasive aspergillosis. Transgenic mice had a threefold greater survival, a 74% lower lung fungal burden, a greater magnitude of lung KC induction, and an earlier and higher peak of lung neutrophil influx compared with wild-type mice. In addition to a higher number of neutrophils, we found a 1.8-fold higher number of monocytes-macrophages in the lungs of transgenic mice as compared with wild-type mice. Furthermore, transgenic mice had greater lung expression of interferon-gamma and interleukin-12 in response to infection, suggesting that transgenic expression of KC indirectly regulated the expression of other cytokines associated with improved host defense against this pathogen. Taken together, these data suggest that overexpression of KC in the lung in the setting of established invasive aspergillosis results in improved host defense and outcome of disease.

The level of leptin [the obese (ob) gene product] mRNA is markedly elevated in hypothyroid male rats. The administration of tri-iodothyronine (T3) to hypothyroid rats resulted in a 40% decrease in leptin mRNA at 8 h. This decrease in leptin mRNA was associated with a parallel decline in circulating leptin levels of about 50% at 24 h. Conversely, beta 3-adrenergic receptor mRNA levels were markedly decreased in epididymal adipose tissue from hypothyroid rats. T3 administration resulted in a 147% increase at 12 h in beta 3-adrenergic receptor mRNA. There was a corresponding increase due to T3 in the lipolytic response to the specific beta 3-adrenergic agonist CL 316,243 that paralleled the increase in beta 3-adrenergic receptor mRNA. T3-mediated changes in leptin and beta 3-adrenergic receptor mRNAs were blocked by cycloheximide, suggesting the involvement of short-lived proteins in these effects. The present results indicate that T3 has opposite effects to those of insulin on the white adipose tissue of rats with respect to leptin mRNA expression.