Lymphotactin gene expression in mast cells following Fc(epsilon) receptor I aggregation: modulation by TGF-beta, IL-4, dexamethasone, and cyclosporin A

Recruitment of lymphocytes is a prominent feature of allergic inflammation. However, the mechanisms by which lymphocytes are attracted to such sites are not understood. Recently, cDNAs encoding a lymphocyte-specific chemokine, lymphotactin (Ltn), were isolated from mouse pro-T cell and human CD8+ T cell libraries, leading us to hypothesize that mast cells might also produce Ltn. Using the reverse transcriptase-PCR and Northern blot analysis, we found that the Ltn gene is inducible in C1.MC/C57.1 and murine bone marrow-cultured mast cells (BMCMC) by Fc(epsilon)RI aggregation. Activation of a human mast cell (HMC-1) or basophil cell line (KU812) similarly led to transcription of Ltn. Fc(epsilon)RI aggregation-dependent Ltn mRNA expression was detected by 1 to 2 h, maximal at 6 h, independent of de novo protein synthesis, and was inhibited by cyclosporin A and dexamethasone. Compared with macrophage inflammatory protein alpha (MIP-1alpha), Fc(epsilon)RI-dependent Ltn and MIP-1alpha mRNA levels were up-regulated by IL-4, but not IFN-gamma, although higher levels of IL-4 (100 and 1000 U/ml) inhibited Ltn expression only; and TGF-beta preferentially enhanced Fc(epsilon)RI-dependent Ltn mRNA levels, suggesting that Ltn and MIP-1alpha have shared and unique regulatory mechanisms. A rabbit polyclonal Ab against a synthetic peptide was developed for use in immunoblot analysis and detected a 15-kDa Ltn protein within mast cell pellets and in the supernatants of mast cells following Fc(epsilon)RI aggregation. Ltn is thus expressed in mast cells and may contribute to the recruitment of lymphocytes to areas of allergic inflammation.

Activated lymphocytes induce promoter activity of the TCA3 gene in mast cells following cell-to-cell contact

Aggregates of mast cells and lymphocytes have been found in inflamed tissues suggesting that lymphocytes may have the ability to activate mast cells through cell-to-cell contact. To examine this hypothesis, murine mast cells were transfected with a T cell activation gene-3 (TCA3)-chloramphenicol acetyl transferase (CAT) construct, and these cells co-cultured with murine EL-4 (T), CH12.LX (B), WEHI-3 (myelomonocytic) or 3T3(fibroblast) cell lines. Co-culture of activated EL-4 or CH12.LX cells, but not WEHI-3 or 3T3 cells, with transfected mast cells induced a 5 to 7 fold increase in CAT expression which was dependent on the lymphocyte to mast cell ratio. Supernatants from activated EL-4 or CH12.LX cells did not induce CAT expression in transfected mast cells. These data demonstrate that activated lymphocytes have the ability to induce the promoter of the TCA3 gene in mast cells through a mechanism requiring cell-to-cell contact, and suggest the possibility that activated lymphocytes may effect other biologic processes in mast cells as well through such heterotypic activation.

Identification of a point mutation in the catalytic domain of the protooncogene c-kit in peripheral blood mononuclear cells of patients who have mastocytosis with an associated hematologic disorder

Both stem cells and mast cells express c-kit and proliferate after exposure to c-kit ligand. Mutations in c-kit may enhance or interfere with the ability of c-kit receptor to initiate the intracellular pathways resulting in cell proliferation. These observations suggested to us that mastocytosis might in some patients result from mutations in c-kit. cDNA synthesized from peripheral blood mononuclear cells of patients with indolent mastocytosis, mastocytosis with an associated hematologic disorder, aggressive mastocytosis, solitary mastocytoma, and chronic myelomonocytic leukemia unassociated with mastocytosis was thus screened for a mutation of c-kit. This analysis revealed that four of four mastocytosis patients with an associated hematologic disorder with predominantly myelodysplastic features had an A-->T substitution at nt 2468 of c-kit mRNA that causes an Asp-816-->Val substitution. One of one patient examined who had mastocytosis with an associated hematologic disorder had the corresponding mutation in genomic DNA. Identical or similar amino acid substitutions in mast cell lines result in ligand-independent autophosphorylation of the c-kit receptor. This mutation was not identified in the patients within the other disease categories or in 67 of 67 controls. The identification of the point mutation Asp816Val in c-kit in patients with mastocytosis with an associated hematologic disorder provides insight not only into the pathogenesis of this form of mastocytosis but also into how hematopoiesis may become dysregulated and may serve to provide a means of confirming the diagnosis, assessing prognosis, and developing intervention strategies.

Topical delivery of growth hormone releasing peptide using liposomal systems: an in vitro study using hairless mouse skin

The results of this study clearly demonstrates the utility of novel non-ionic liposomal systems in facilitating transfer of GHRP-6 into and across deeper strata of skin following topical application. These findings indicate that it may be possible to deliver therapeutic doses of a wide variety of peptides to local skin tissue via topical application. The results also suggest the possibility of controlled enhancement of skin penetration or metered polypeptide deposition through appropriate choice of liposomal lipid components. The pronounced enhancement of GHRP-6 and mannitol transport from emulsions containing the nonionic lipids suggests a promising delivery system for hydrophilic drugs in general.

The role of c-Kit and its ligand, stem cell factor, in mast cell apoptosis

The regulation of tissue mast cell number depends both on the rate of production of mast cell precursors and the length of survival of mature mast cells within tissues. Once mast cell precursors target to tissues, their survival may largely be dependent upon the local production of stem cell factor (SCF). Withdrawal of interleukin (IL)-3 results in mast cell apoptosis. The apoptotic changes following IL-3 deprivation are prevented by the addition of SCF which exerts its rescue effect upon interaction with its c-Kit tyrosine kinase receptor. Mast cells undergo apoptosis on withdrawal of IL-3 coincident with a decrease in endogenous bcl-2 mRNA; however, SCF does not induce expression of bcl-2 when added to these cells. When overexpressed, bcl-2 prolongs survival of bcl-2-transfected mast cells following IL-3 deprivation. Transforming growth factor-beta was found to specifically prevent this SCF-mediated rescue from apoptosis, probably by down-regulating the expression of c-Kit. Thus, microenvironmental factors play an important role in regulating mast cell numbers by effecting survival in the periphery.

Transcriptional regulation of the TCA3 gene in mast cells after Fc epsilon RI cross-linking

TCA3 is a pro-inflammatory cytokine expressed in mast cells after activation. To examine how this gene is regulated, TCA3 mRNA levels were examined and nuclear run-on experiments and promoter analysis were performed. Northern blot analysis showed that TCA3 message appeared in mast cells within 2 h after induction, with a t1/2 of 30 min. Nuclear run-on experiments revealed that the appearance of TCA3 mRNA occurred in large part because of an increase in the level of de novo transcription. Analysis of the promoter region demonstrated that inducible gene expression was directed by a region extending between 1.324 kb and 0.082 kb upstream from the transcription start site. There was a 60- to 80-fold induction with TCA3 CAT constructs extending between 1.324 kb and 0.324 kb upstream from the transcription start site after treatment with PMA/A23187 and a 30- to 40-fold induction with Fc epsilon RI cross-linking. There was a seven- to eightfold induction with the region extending between 0.136 kb and 0.082 kb upstream from the transcription start site. TCA3 CAT constructs containing regions encompassing either the 0.042 kb or 2.0 kb sequence from the transcription start site were not able to direct CAT-protein synthesis. The TCA3 5' flanking sequence contained negative regulatory activity. Electrophoretic mobility shift assays revealed that protein in nuclear extracts of activated mast cells bound to an NF-kappa B element of the TCA3 gene. These findings demonstrate that the TCA3 gene is regulated transcriptionally in mast cells, with minimal promoter sequences contained within the 0.082 kb upstream region of the TCA3 gene; a putative enhancer NF-kappa B element is contained between 0.324 kb and 0.136 kb and a putative inhibitory element is contained between 1.324 kb and 2.0 kb upstream from the transcription start site.

Transcriptional regulation of the TCA3 gene in mast cells after Fc epsilon RI cross-linking

TCA3 is a pro-inflammatory cytokine expressed in mast cells after activation. To examine how this gene is regulated, TCA3 mRNA levels were examined and nuclear run-on experiments and promoter analysis were performed. Northern blot analysis showed that TCA3 message appeared in mast cells within 2 h after induction, with a t1/2 of 30 min. Nuclear run-on experiments revealed that the appearance of TCA3 mRNA occurred in large part because of an increase in the level of de novo transcription. Analysis of the promoter region demonstrated that inducible gene expression was directed by a region extending between 1.324 kb and 0.082 kb upstream from the transcription start site. There was a 60- to 80-fold induction with TCA3 CAT constructs extending between 1.324 kb and 0.324 kb upstream from the transcription start site after treatment with PMA/A23187 and a 30- to 40-fold induction with Fc epsilon RI cross-linking. There was a seven- to eightfold induction with the region extending between 0.136 kb and 0.082 kb upstream from the transcription start site. TCA3 CAT constructs containing regions encompassing either the 0.042 kb or 2.0 kb sequence from the transcription start site were not able to direct CAT-protein synthesis. The TCA3 5' flanking sequence contained negative regulatory activity. Electrophoretic mobility shift assays revealed that protein in nuclear extracts of activated mast cells bound to an NF-kappa B element of the TCA3 gene. These findings demonstrate that the TCA3 gene is regulated transcriptionally in mast cells, with minimal promoter sequences contained within the 0.082 kb upstream region of the TCA3 gene; a putative enhancer NF-kappa B element is contained between 0.324 kb and 0.136 kb and a putative inhibitory element is contained between 1.324 kb and 2.0 kb upstream from the transcription start site.

Methods in pathology. An improved method for DNA diagnosis of leprosy using formaldehyde-fixed, paraffin-embedded skin biopsies

To improve the sensitivity of the previously reported polymerase chain reaction (PCR) for the detection of Mycobacterium (M.) leprae in the formaldehyde-fixed, paraffin-embedded tissues, we adapted the PCR designed to amplify an internal 372 bp fragment of a M. leprae-specific repetitive sequence to 39 skin biopsies taken from patients with leprosy of the lepromatous type and tuberculoid type. Crude DNA samples were prepared from tissue sections that were deparaffinized and subjected to proteinase-K digestion without any further treatment for DNA purification. Overcoming a false-negative reaction by an elongation of the period for enzymatic digestion and an appropriate dilution of the samples, an amplification of the target sequence was obtained as a single band with all 39 skin biopsies tested. The fragments specifically amplified by the PCR were subjected to direct sequencing and were confirmed to be identical with an internal 372 bp of M. leprae-specific repetitive sequence. Although in nine of 24 nonleprosy control samples, a false-positive amplification was observed as from one to several bands, they were distinguishable from the specific one by the electrophoretic pattern. This PCR makes up for the classic histological methods used in the diagnosis of leprosy.

The intestinal uptake of "enzymatically-stable" peptide drugs in rats as influenced by D-glucose in situ

In previous in situ and in vivo rat perfusion studies, the intestinal absorption of several low molecular weight drugs was increased by the presence of luminal D-glucose. The intent of this study was to determine the potential of this fed-state effect to improve the intestinal uptake of poorly permeable, small peptide and peptide-like drugs. Jejunal wall permeabilities (Pw*) of di-(D-kyotorphin), tri-(cephradine), hexa-(growth hormone releasing peptide, GHRP-6) and octa-(octreotide, a somatostatin analogue) peptides and corresponding net water fluxes were determined in rats using an in situ single-pass perfusion technique. Glucose was shown to enhance the uptake of the smaller (di- and tri-) peptides but not the larger peptides despite the fact that glucose elicited a significant net water absorption with each of the four peptide drugs. It is concluded that glucose enhances jejunal permeabilities of smaller peptides by solvent drag and the enhancement is limited in situ by peptide molecular size. The studies with nonmetabolizable 3-O-methylglucose suggest that the augmentation of the proton gradient across the transmucosal membrane by glucose contributes to the carrier-mediated transport observed with the smaller peptides.

IL-3-dependent murine mast cells undergo apoptosis on removal of IL-3. Prevention of apoptosis by c-kit ligand

It is well established that mast cell proliferation and maturation are regulated by two principle cytokines, IL-3 and the c-kit ligand stem cell factor (SCF). Little is known, however, how these two processes are negatively regulated and thus, how mast cell number is controlled in normal or pathologic processes. In this study we hypothesized that IL-3-dependent mast cells would undergo programmed cell death (apoptosis) on removal of IL-3 as was shown with other growth factor-dependent hemopoietic cells. Apoptotic changes were analyzed using light microscopy, fluorescent staining with acridine orange, flow cytometric analysis, and DNA electrophoresis. We could demonstrate that elimination of IL-3 from either primary bone marrow-derived cultured mast cell cultures (BMCMC) or from the growth factor-dependent mast cell line MCP5 resulted in the characteristic changes of apoptosis including condensed chromatin, fragmented nuclei, cellular vacuolization, typical pattern of propidium iodide or Hoechst 33342 uptake by flow cytometry, and the characteristic 200 bp "ladder" pattern of DNA cleavage. These events were prevented by SCF, an action that was in part mediated by tyrosine kinases, in that the tyrosine kinase inhibitor herbimycin inhibited the action of SCF in preventing apoptosis in IL-3-deprived cells. By using anti c-kit mAb and IL-3-dependent BMCMC obtained from W/Wv mice homozygous for mutation at the w locus that encodes the c-kit receptor, we could also show that SCF exerted its effect via c-kit. Neither dexamethasone nor cyclosporin A inhibited the "rescue" effect of SCF, suggesting that "rescue" was mediated by SCF and not through the induction of other cytokines. Thus, IL-3-dependent mast cells undergo apoptosis on removal of IL-3, an event that is prevented by the addition of SCF through its ligand c-kit, thus demonstrating how these principle mast cell growth factors may act in concert to regulate mast cell number under physiologic conditions.

IL-3-dependent murine mast cells undergo apoptosis on removal of IL-3. Prevention of apoptosis by c-kit ligand

It is well established that mast cell proliferation and maturation are regulated by two principle cytokines, IL-3 and the c-kit ligand stem cell factor (SCF). Little is known, however, how these two processes are negatively regulated and thus, how mast cell number is controlled in normal or pathologic processes. In this study we hypothesized that IL-3-dependent mast cells would undergo programmed cell death (apoptosis) on removal of IL-3 as was shown with other growth factor-dependent hemopoietic cells. Apoptotic changes were analyzed using light microscopy, fluorescent staining with acridine orange, flow cytometric analysis, and DNA electrophoresis. We could demonstrate that elimination of IL-3 from either primary bone marrow-derived cultured mast cell cultures (BMCMC) or from the growth factor-dependent mast cell line MCP5 resulted in the characteristic changes of apoptosis including condensed chromatin, fragmented nuclei, cellular vacuolization, typical pattern of propidium iodide or Hoechst 33342 uptake by flow cytometry, and the characteristic 200 bp "ladder" pattern of DNA cleavage. These events were prevented by SCF, an action that was in part mediated by tyrosine kinases, in that the tyrosine kinase inhibitor herbimycin inhibited the action of SCF in preventing apoptosis in IL-3-deprived cells. By using anti c-kit mAb and IL-3-dependent BMCMC obtained from W/Wv mice homozygous for mutation at the w locus that encodes the c-kit receptor, we could also show that SCF exerted its effect via c-kit. Neither dexamethasone nor cyclosporin A inhibited the "rescue" effect of SCF, suggesting that "rescue" was mediated by SCF and not through the induction of other cytokines. Thus, IL-3-dependent mast cells undergo apoptosis on removal of IL-3, an event that is prevented by the addition of SCF through its ligand c-kit, thus demonstrating how these principle mast cell growth factors may act in concert to regulate mast cell number under physiologic conditions.

Absorption characteristics of insulin through the buccal mucosa

The purpose of the study was to investigate absorption characteristics of insulin through the buccal mucosa by studying the influence of application time of the buccal cell on the hypoglycemic response as well as the plasma insulin level. Three application times of the buccal cell (0.5, 1.0 and 1.5 h) were studied. A marked increase in the extent of hypoglycemia was observed when the application time was extended from 0.5 to 1.0 h. Correspondingly, the amount of insulin absorbed increased in the same order. However, a further increase in application time from 1.0 to 1.5 h did not seem to significantly enhance the hypoglycemic response. This finding was also confirmed by the insulin blood levels. It can be suggested that a certain amount of time is required for insulin molecules to be taken up by the buccal mucosa. Tmax of hypoglycemia was observed about 1.0 h after the removal of the cell, irrespective of the application time. Absorption profile of plasma insulin was found to be application time-dependent. These results can be attributed to the reservoir function of the buccal mucosa and time-dependent equilibrium of insulin with the buccal mucosa.

Biopharmaceutic aspects of buccal absorption of insulin

Absorption of insulin through buccal mucosa was investigated using rabbits as animal model. The effects of various dose sizes, pH of the insulin solutions and a series of sorption enhancers or absorption promoters on the hypoglycemic response were studied using a buccal cell. In the absence of sorption promoters, the various dose sizes and pH of the administered insulin solution did not show any significant hypoglycemic response, indicating that substantial amounts of insulin were not absorbed through the buccal mucosa. In the presence of sorption enhancers, the extent of hypoglycemia was significantly enhanced in terms of AUC and Cmax. Among the sorption enhancers investigated, Brij 35 was the most satisfactory one, followed by sodium taurocholate, sodium laurylsulfate, sodium deoxycholate, sodium methoxysalicylate, sodium dextransulfate and EDTA. An inverse correlation was found between extent of hypoglycemia and light scattering intensity of insulin solution. The extent of hypoglycemia in presence of Brij 35 was concentration-dependent although a plateau was observed at high concentration range. The maximum pharmacological availability obtained from buccal administration of insulin solution was about 12%, while that obtained with the tablet formulation was about 4.3%.

Localization of genomic regions specific for the attenuated, mouse-adapted poliovirus type 2 strain W-2

In order to begin to elucidate the genomic basis of the attenuation of mouse-adapted, poliovirus type 2 strain W-2 (PV2/W-2), we have cloned and sequenced the virus and compared it with the virulent, mouse-adapted PV2/Lansing strain. In addition, we have performed computer-generated comparisons of PV2/W-2 to the non-mouse-adapted, attenuated PV2/Sabin strain to determine whether mutational patterns occur that result in attenuation. The PV2/W-2 genome is 7434 nucleotides in length, which is three bases shorter than PV2/Lansing. The 5' non-coding region of PV2/W-2 is 747 nucleotides in length (compared to 744 in PV2/Lansing) and shares 98.8% identity with PV2/Lansing and 82.3% identity with PV2/Sabin. Overall, the PV2/W-2 polyprotein (2205 amino acids) is two amino acids shorter than that of either PV2/Lansing or PV2/Sabin (2207 amino acids). These contiguous deletions fall within the P3-D region (polymerase). Within these 2205 amino acid residues only 26 differences were observed between PV2/W-2 and PV2/Lansing (98.8% identity), whereas 92 occurred between PV2/W-2 and PV2/Sabin (95.8% identity). The 3' non-coding region of PV2/W-2 is 72 nucleotides in length and shares 100% identity with PV2/Lansing and 98.6% identity with PV2/Sabin. Amino acid changes in the capsid protein region occurred in neutralization sites 1 and 3, areas previously shown to be important for pathogenicity. The cleavage site between non-structural proteins P2-C/P3-A consisted of a glutamine-serine pair, in contrast to other sequenced polioviruses which have a glutamine-glycine dipeptide.

Insights into Theiler's virus neurovirulence based on a genomic comparison of the neurovirulent GDVII and less virulent BeAn strains

Theiler's murine encephalomyelitis viruses (TMEV) are naturally occurring enteric pathogens of mice which can be divided into two subgroups based primarily on their neurovirulence after intracerebral inoculation: the highly virulent GDVII group and the less virulent TO strains. To begin to elucidate the molecular basis of neurovirulence of the two TMEV subgroups, we have cloned and sequenced the entire 8105 nucleotide RNA genome of the highly virulent GDVII virus and compared it to the less virulent BeAn 8386 virus (D. C. Pevear, M. Calenoff, E. Rozhon, and H. L. Lipton (1987) J. Virol. 61, 1507-1516). The viruses are 90.4% identical at the nucleotide level. The highest level of nucleotide identity is in the 5' and 3' noncoding regions of the RNAs (95.5 and 99.2%, respectively): regions believed to be important for control of viral RNA synthesis, initiation of translation, encapsidation, and virion uncoating. The 2303 amino acid polyproteins of BeAn and GDVII viruses are 95.7% identical at the amino acid level (99 of 2303 residues differed). Thirty-nine of these amino acid differences occur in the three surface coat proteins, VP1 (20 differences), VP2 (10 differences), and VP3 (9 differences), while the remainder of the changes are distributed throughout the polyprotein. Although these levels of identity are too low to determine where neurovirulence maps based solely on nucleotide sequence analysis, having the complete sequence will facilitate construction of recombinant BeAn-GDVII viruses to be used for this purpose.