Biomedical subjects

Jeffrey K Actor

Publications and source records attributed to Jeffrey K Actor.

8 recordsLinked to original sources

PubMed2003

Substance P expression correlates with severity of diarrhea in cryptosporidiosis.

Cryptosporidiosis, caused by Cryptosporidium parvum, is self-limited in immunocompetent hosts but may cause chronic diarrhea in patients with acquired immunodeficiency syndrome (AIDS). Substance P (SP), a neuropeptide belonging to the tachykinin family, is expressed in gastrointestinal tract and can cause electrogenic chloride anion secretion. Therefore, we studied SP mRNA and protein expression in jejunal tissue samples of patients with AIDS with naturally occurring chronic cryptosporidiosis and healthy volunteers with mild cryptosporidiosis or asymptomatic infection after experimental C. parvum challenge. SP mRNA was associated with symptoms in cryptosporidiosis. SP protein levels were greater in symptomatic than asymptomatic volunteers. Similarly, greater expression of SP mRNA and protein were noted in patients with AIDS with chronic cryptosporidiosis versus immunocompetent volunteers with self-limited infection. This study demonstrates a direct correlation between SP levels and disease severity and may imply that SP plays a role in diarrhea mediation.

AIDS-Related Opportunistic Infections↗

PubMed2003

Asian and Siberian ginseng as a potential modulator of immune function: an in vitro cytokine study using mouse macrophages.

BACKGROUND: Ginseng is a widely used herbal product in China, other Asian countries, and in the Unites States. There is a traditional belief that ginseng stimulates immune functions. In this study, the innate effects of Asian and Siberian ginsengs on cytokines and chemokines produced by cultured macrophages were examined. MATERIALS AND METHODS: The effects of Asian and Siberian ginseng on cytokines and chemokines produced by cultured macrophages were examined. Mouse macrophages (J774A.1) were incubated with Asian or Siberian ginseng at varying concentrations (1, 10, 100, and 1000 microg/ml) for 24 h and then harvested for RNA isolation. The expression levels of IL-1beta, IL-12, TNF-alpha, MIP-1 alpha, and MIP-2 mRNA were measured by quantitative PCR. RESULTS: Our data showed that Asian ginseng induced a statistically significant increase in IL-12 expression at both mRNA and protein levels. However, the minor twofold increase is probably biologically insignificant. No significant increase of IL-12 by Siberian ginseng was observed at any dose level studied. No significant change in IL-1beta, IL-15, TNF-alpha, or MIP-1alpha mRNA was observed by either Asian or Siberian ginseng treatment. CONCLUSIONS: Our data showed statistically significant differential regulation of IL-12 by Asian ginseng. Siberian ginseng did not show a statistically significant increase. We conclude that both Asian ginseng and Siberian ginseng cannot significantly stimulate innate macrophage immune functions that influence cellular immune responses. Therefore, contrary to the popular belief, Asian and Siberian ginseng may not stimulate immune function.

Adjuvants, Immunologic↗

PubMed2003

Cord factor trehalose 6,6'-dimycolate (TDM) mediates trafficking events during mycobacterial infection of murine macrophages.

The persistence of tuberculosis within pulmonary granulomatous lesions is a complex phenomenon, with bacterial survival occurring in a focal region of high immune activity. In part, the survival of the organism may be linked to the ability of the surface glycolipid trehalose 6,6'-dimycolate (TDM; cord factor) to inhibit fusion events between phospholipid vesicles inside the host macrophage. At the same time, TDM contributes to macrophage activation and a cascade of events required for initiation and maintenance of granulomatous responses. This allows increased sequestration of organisms and further survival and persistence within host tissues. Bacterial viability, macrophage cytokine and chemokine response, and intracellular trafficking were investigated in Mycobacterium tuberculosis from which TDM had been removed. Removal of surface lipids led to enhanced trafficking of organisms to acidic compartments; reconstitution of delipidated organisms with either pure TDM or the petroleum ether extract containing crude surface lipids restored normal responses. Use of TDM-coated polystyrene beads demonstrated that TDM can mediate intracellular trafficking events, as well as influence macrophage production of pro-inflammatory molecules. Thus, the presence of TDM may be an important determinant for successful infection and survival of M. tuberculosis within macrophages.

Animals↗

PubMed2002

In vivo digoxin-like immunoreactivity in mice and interference of Chinese medicine Danshen in serum digoxin measurement: elimination of interference by using a chemiluminescent assay.

BACKGROUND: Danshen, a traditional Chinese medicine used in the management of cardiovascular diseases, is available without prescription in the US. Because Danshen is used to treat cardiovascular diseases, we studied the potential interference of Danshen with serum digoxin measurement using various immunoassays. METHODS: Blood was collected 1 day before and then 1 and 2 h after feeding mice with Danshen. The apparent digitoxin activities were measured by the fluorescence polarization immunoassay (FPIA). We also added microliter amounts of Danshen extract to digoxin pools prepared from patients receiving digoxin. The digoxin concentrations were measured using the fluorescence polarization immunoassay (FPIA), microparticle enzyme immunoassay (MEIA) and chemiluminescent assay (CLIA). The observed values were compared with original values. We also fed mice with Danshen. RESULTS: We observed measurable digoxin-like immunoreactivity in sera of mice after feeding with Danshen. We also observed falsely lower digoxin concentrations (negative interference) when MEIA was used for digoxin measurement. However, serum digoxin concentrations were falsely elevated with FPIA. We observed no interference of Danshen in serum digoxin measurement using the CLIA. CONCLUSION: Danshen appears to contain digoxin-like immunoreactivity but does not interfere with serum digoxin measurement when CLIA was used.

Animals↗

PubMed2002

Activated charcoal is more effective than equilibrium dialysis in removing Chinese medicines Chan Su and Dan Shen from serum and activated charcoal also prevents further absorption of these agents from G.I. tract in mice: monitoring the effect in clinical laboratory by measuring digoxin activity in serum.

BACKGROUND: Chinese medicines are freely available without prescription and are widely used by the general population. Chan Su and Dan Shen are both indicated for the treatment of cardiac diseases. Severe toxicity from Chan Su has been reported. We studied the possibility of removing Chan Su and Dan Shen from human sera using activated charcoal and equilibrium dialysis, and also examined the potential benefit of preventing absorption of these agents from the G.I. tract in the mouse model. METHODS: For in vitro studies, drug-free serum pools were supplemented with Chan Su or Dan Shen and then either treated with activated charcoal (10 and 25 mg/ml), or passed through a column packed with activated charcoal. Serum pools supplemented with Chan Su or Dan Shen were also subjected to equilibrium dialysis against phosphate buffer (pH 7.4) using dialysis membrane with molecular cut-off of 25,000 Da. Removal of Chan Su or Dan Shen from the serum was monitored by measuring the apparent digoxin concentration using the fluorescence polarization immunoassay (FPIA) for digoxin (Abbott Laboratories). RESULTS: We observed the fast and effective removal of both Chan Su and Dan Shen from the serum by activated charcoal. We also observed significant removal of both Chan Su and Dan Shen when the serum pools containing these Chinese medicines were passed through columns packed with activated charcoal. Although equilibrium dialysis was also effective in removing these Chinese medicines from the serum, 24 h was required for complete removal of Dan Shen activity, and for Chan Su, complete removal was not achieved even after 24 h. In our in vivo model, we observed significantly less digoxin activity in the group of mice that received activated charcoal compared to the control group. CONCLUSIONS: Activated charcoal is effective in preventing absorption of these Chinese medicines from the G.I. tract and can also remove these agents from the serum.

Animals↗

PubMed2002

Lactoferrin immunomodulation of DTH response in mice.

Improved nontoxic adjuvants, especially adjuvants capable of inducing cell-mediated immunity (CMI), are needed for research in immunology and for development of human and veterinary vaccines. Bovine Lactoferrin, an effector molecule shown to directly participate in host defense, was assessed at various concentrations as an adjuvant component for induction of DTH responses to sheep red blood cells (SRBC). Subcutaneous immunization with Lactoferrin enhanced delayed type hypersensitivity (DTH) in CBA mice in a dose-dependent fashion; DTH responses were most significantly increased when sensitization was accomplished using Lactoferrin at 50 microg/dose and 250 microg/dose. Furthermore, Lactoferrin admixed with suboptimal dose of SRBC enhanced DTH responses by over 17-fold. Peritoneal cells collected from mice intraperitoneally injected with a 100 microg/dose of Lactoferrin demonstrated modest, but significant, production of TNF-alpha, IL-12 and MIP-1alpha when cultured in vitro, compared to saline-injected controls. J774A.1 murine macrophages stimulated with Lactoferrin resulted in increased TNF-alpha protein production, and upregulated IL-12 and IL-15 mRNA. Levels of message for chemokines MIP-1alpha and MIP-2 were also increased in a dose-dependent way. Taken together, these results indicate that Lactoferrin as an adjuvant may stimulate macrophages to generate a local environment likely to push immune responses towards development and maintenance of CMI.

Adjuvants, Immunologic↗

PubMed2002

Influence of trehalose 6,6'-dimycolate (TDM) during mycobacterial infection of bone marrow macrophages.

The relative role of surface lipids in the innate macrophage response to infection with mycobacteria remains unknown. Trehalose 6,6'-dimycolate (TDM), a major component of the mycobacterial cell wall, can elicit hypersensitive as well as T-cell-independent foreign body responses. The T-cell-independent contribution of TDM to the primary macrophage response to mycobacterial infection was investigated. Bone-marrow-derived macrophages isolated from C57BL/6 mice were infected with native Mycobacterium tuberculosis (MTB) or with MTB delipidated using petroleum ether extraction methods. The removal of surface lipids caused decreased bacterial survival in macrophages, but there was no loss of bacterial growth in broth culture. Bacterial survival within macrophages was restored upon reconstitution of the bacteria with purified TDM. The cytokine and chemokine parameters of the macrophage responses were also investigated. The amounts of IL-1beta, TNF-alpha, IL-6 and MIP-1alpha produced were significantly reduced following delipidation, but were restored upon reconstitution with TDM. The amount of IL-12 produced, but not the amount of IL-10 produced, was also significantly reduced upon macrophage infection with delipidated MTB. Furthermore, nitric oxide responses were not impaired upon infection with delipidated MTB, suggesting that intracellular survival and macrophage secretion of cytokines and chemokines are differentially controlled. These studies indicate that TDM is a major component contributing to the innate macrophage responses to MTB infection.

Animals↗

PubMedDate not supplied

Mycobacterial glycolipid cord factor trehalose 6,6'-dimycolate causes a decrease in serum cortisol during the granulomatous response.

Serum cortisol levels were evaluated in mice following intravenous administration of purified mycobacterial glycolipid trehalose 6,6'-dimycolate (TDM). C57BL/6 mice develop lung granulomas in response to TDM, while A/J mice are deficient in this process. Administration of TDM to C57BL/6 mice led to a rapid reduction in serum cortisol, concurrent with initiation of the granulomatous response and cytokine and chemokine mRNA induction. Cortisol levels were lowest on day 5 after TDM administration, but there was significant production of IL-6, TNF-alpha and IL-1beta messages. Granuloma formation and full immune responsiveness to TDM were only apparent upon a sufficient decrease in levels of systemic cortisol. Treatment of the C57BL/6 mice with hydrocortisone abolished inflammatory responses. Histologically nonresponding A/J mice exhibited higher constitutive serum cortisol and demonstrated different kinetics of cortisol reduction upon administration of TDM. A/J mice demonstrated hyperplastic morphology in the suprarenal gland with a high degree of vacuolization in the medullary region and activation of cells in the zona fasciculata and zona reticularis. The A/J mice were dysregulated with respect to cytokine responses thought to be necessary during granuloma formation. The high constitutive serum cortisol in the A/J mice may therefore contribute to pulmonary immunoresponsiveness and the establishment of an environment counterproductive to the initiation of granulomatous responses. The identification of a mycobacterial glycolipid able to influence serum cortisol levels is unique and is discussed in relation to immunopathology during tuberculosis disease.

Adrenal Cortex↗