HLA-restricted lysis of herpes simplex virus-infected monocytes and macrophages mediated by CD4+ and CD8+ T lymphocytes

Freshly isolated human peripheral blood monocytes and in vitro monocyte-derived macrophages were infected with HSV type 1 and used as target cells in a cell-mediated cytotoxicity assay. PBMC from both HSV-immune and non-immune donors were stimulated in vitro for 5 days with UV-inactivated HSV Ag and used as effector cells. Effectors from HSV-immune donors mediated virus-specific lysis of both monocyte and macrophage targets, whereas effectors from non-immune donors failed to mediate target cell lysis. Mean virus-specific lysis of autologous monocytes was (8.5 +/- (+/- 2.0)%) compared to a threefold greater virus-specific lysis of autologous macrophages (24.7 (+/- 4.3)%). More than 70% of this lysis was mediated by CD16- T lymphocytes. Further analysis demonstrated that the majority of the lysis against autologous and allogeneic targets was HLA-DR-restricted and mediated by CD4+ CTL. However, CD8+ CTL also contributed to the lysis of autologous targets as well as allogeneic targets having a common HLA-A and/or -B determinant. The HLA-restricted cytotoxicity was virus-specific as HSV-infected, but not CMV-infected, cells were lysed. CTL-mediated lysis of HSV-infected monocytes and macrophages may be of significance in the anti-viral and immunoregulatory host response.     

In vivo activity of lymphokine-activated macrophages in host defense against neoplasia

Purified splenic macrophage (M phi) from normal DBA/2J mice and mice bearing P815 tumors were examined for responsiveness to lymphokine (LK) preparations containing high concentrations of IFN-gamma. For both normal and tumor-bearing M phi, LK treatment induced morphologic changes and increased the percentage of Ia+ cells from 35 to 55%. Although neither population exhibited spontaneous cytotoxicity toward P815 targets, LK treatment induced considerable tumoricidal activity in tumor-bearing M phi (32 to 80% lysis) but only minimal activity in normal M phi (8 to 17% lysis). Subcutaneous injection of 1 X 10(6)P815 cells into DBA/2J led to progressive tumor growth and death of 100% of the recipients after 27 +/- 3 days. Injection of a 1:18 mixture of P815 with either LK-activated normal or tumor-bearing M phi caused tumor regression after 10 days, and prolonged life until 43 +/- 4 days with tumor-bearing M phi and 39 +/- 3 days with normal M phi. Untreated normal or tumor-bearing M phi were unable to cause the effect (30 +/- 2 days), and lymphocytes could not be substituted for M phi (25 +/- 3 days). In x-irradiated recipients, no effect of LK-activated M phi could be observed (control = 19 +/- 2 days; LK-activated tumor-bearing M phi = 21 +/- 3 days). In addition, administration of an admixture of LK-treated M phi and x-rayed tumor before challenge with viable P815 enabled the recipient to inhibit tumor growth and caused tumor necrosis with inflammatory cell infiltration of the tumor. These observations suggest that, in part, LK-activated M phi may interact in vivo with host-derived cellular components and enhance the immune reactivity of the host against the tumor.     

Determination of the T-cell subset producing gamma-interferon in tuberculous pleural effusion

The percentage of cells of different T-cell subsets and their functions in tuberculous pleural effusion were investigated. The percentage of OKT4-positive cells was 65 +/- 2% (mean +/- SEM, n = 8) and that of OKT8-positive cells was 19 +/- 3% (n = 8). Pleural T lymphocytes of patients with tuberculous pleurisy responded well to stimulation with purified protein derivative of tuberculin, and deoxyribonucleic acid synthesis was observed along with gamma interferon (IFN-gamma) production. When pleural T lymphocytes of patients with tuberculous pleurisy were treated with OKT4 monoclonal antibody and complement, a significant decrease in IFN-gamma production was observed in all eight patients (P less than 0.005), whereas no definite decrease in IFN-gamma production was found after treatment with OKT8 monoclonal antibody and complement. These results suggest that at least the OKT4+/OKT8- T-cell subset is responsible for the antigen-specific IFN-gamma production in pleural T lymphocytes of patients with tuberculous pleurisy.     

Deficient in vitro and in vivo phagocytosis of apoptotic T cells by resident murine alveolar macrophages

Apoptotic lymphocytes are readily identified in murine lungs, both during the response to particulate Ag and in normal mice. Because apoptotic lymphocytes are seldom detected in other organs, we hypothesized that alveolar macrophages (AMphi) clear apoptotic lymphocytes poorly. To test this hypothesis, we compared in vitro phagocytosis of apoptotic thymocytes by resident AMphi and peritoneal macrophages (PMphi) from normal C57BL/6 mice. AMphi were deficient relative to PMphi both in percentage containing apoptotic thymocytes (19.1 +/- 1% vs 96 +/- 2.6% positive) and in phagocytic index (0.23 +/- 0.02 vs 4.2 +/- 0.67). This deficiency was not due to kinetic differences, was seen with six other inbred mouse strains, and was not observed using carboxylate-modified polystyrene microbeads. Annexin V blockade indicated that both Mphi types cleared apoptotic T cells by a mechanism involving phosphatidylserine expression. By contrast, neither mAb blockade of a variety of receptors (CD11b, CD29, CD51, and CD61) known to be involved in clearance of apoptotic cells, nor the tetrapeptide RGDS (arginine-glycine-aspartic acid-serine) blocked ingestion by either type of macrophage. To confirm these studies, apoptotic thymocytes were given intratracheally or i.p. to normal mice, and then AMphi or PMphi were recovered 30-240 min later. Ingestion of apoptotic thymocytes by AMphi in vivo was significantly decreased at all times. Defective ingestion of apoptotic lymphocytes may preserve AMphi capacity to produce proinflammatory cytokines in host defense, but could contribute to development of autoimmunity by failing to eliminate nucleosomes.     

Evaluation of adenosine deaminase seric activity in the diagnosis of bovine tuberculosis

Determination of seric levels of adenosine deaminase (ADA), an enzyme produced by monocytes/macrophages and lymphocytes, has been used in the diagnosis of human tuberculosis (TB). In the present study, ADA seric activity was evaluated comparatively to the comparative tuberculin test in the diagnosis of bovine tuberculosis. Two hundred fifty-six cattle were classified by origin and by the comparative tuberculin test as TB-positive animals (n = 52, from herds where the Mycobacterium bovis had previously been isolated), and TB-negative animals (n = 204, TB-free herds). The mean ADA seric value from the TB-positive group (4.45 +/- 2.33 U/L) was significantly lower (p = 0.008) than that observed in sera from the TB-negative group (6.12 +/- 4.47 U/L). When animals from a herd with clinical cases of enzootic bovine leukosis of TB-negative group were withdrawn from analysis, the mean ADA seric values of TB-negative group (5.12 +/- 3.75 U/L) was not significantly different anymore from that of the TB-positive group (p = 0.28). There was no agreement in the diagnosis of bovine TB between comparative tuberculin test and determination of ADA seric values, using two different cutoff points, being 6.12 U/L and 15.0 U/L, (kappa = -0.086 and kappa = -0.082, respectively). In conclusion, the determination of ADA seric activity was not a good auxiliary test for bovine TB, because it was not able to distinguish between TB-positive and TB-negative animals.     

Activated and memory T lymphocytes in human milk.

Since activated macrophages and cytokines are found in human milk (HM), a flow cytometry study was conducted to determine whether T cells in HM display phenotypic markers of recent or previous activation. HM was collected during the first 3 d of lactation. The Paint-a-Gate program was used to optimize gating on the lymphocyte population. A mean +/- 1 SD of 4 +/- 3% of total HM leukocytes were lymphocytes and 96 +/- 3% were macrophages and granulocytes (N = 33 subjects). HM lymphocyte populations were further analyzed in five subjects. T cells (CD3+) represented 83 +/- 11% and B cells (CD19+) were 6 +/- 4% of HM lymphocytes. The mean CD4/CD8 ratio of T cells in HM was 0.88 (range 0.40-1.25). This ratio was significantly decreased compared to the peripheral blood (PB) of control adults (P less than 0.02) and postpartum women (P less than 0.02), due mostly to a significant increase in CD8+ CD3+ cells in HM compared to the PB of control adults (P less than 0.002) and postpartum women (P less than 0.05). T cells bearing markers of recent activation were significantly increased in HM compared to the PB of control adults: 85 +/- 7% of CD3+ cells in HM were HLA-DR+ (controls, 10 +/- 4%; P less than 0.001), and 15 +/- 6% of CD3+ cells in HM were IL-2R+ (controls, 6 +/- 2%; P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Interactions between heterochronic cells in the formation of delayed-type hypersensitivity.

The effect of ageing on lymphocyte and macrophage functional activity in the induction of tuberculin sensitivity was studied in experiments on 440 CBA mice of three age groups. The capacity of old animals to generate delayed-type hypersensitivity following administration of BCG cells was found to be diminished and their lymphocytes caused decreased hypersensitivity on transplantation. The capacity of recipients to reproduce delayed-type hypersensitivity after thymocyte and bone marrow cell transplantation was influenced by the age of transplanted thymocytes. This capacity was markedly suppressed on the recipients of old cells. The antigen presentation function of macrophage did not after significantly as a function of age.     

Influence of the thymus extract on the immunological function of animals with experimental diabetes

After immunization with SRBC, the number of plaque-forming cells (PFC) in the spleen of alloxan-diabetic mice, in nondiabetic TIR mice and in alloxan-diabetic TIR mice was significantly decreased as compared with control non-diabetic donors. The ability of lymphocytes from alloxan-diabetic mice to adoptively restore the suppressed immune response of TIR mice, was reduced in comparison with the effect of lymphocytes from normal, nondiabetic donors. Local GVH reaction in nondiabetic rat recipients provoked by lymphocytes from control healthy mice was 5.6 +/- 0.7 mm. Significantly lower rate of local GVH reaction after injection of lymphocytes from diabetic donors was found in diabetic as in nondiabetic recipients as well. Treatment of alloxan-diabetic mice with thymus extract or with insulin, partly restored depressed function of the humoral and cellular system. Treatment of diabetic mice with both thymus extract and insulin, was even more effective in restoring of their immune reactivity. Diabetic condition strongly influenced the function of the immune system. This could be attributed to depletion of T-lymphocytes, changed relations between the lymphocyte subpopulations in diabetic donors, and disturbance of lymphocyte metabolism.     

Increase in NGF content and nerve fiber sprouting in human allergic contact eczema

There is increasing evidence for an intimate interaction of the skin and the nervous system. As known from animal studies, nerve growth factor (NGF) is essential for the innervation density and functional properties of sensory neurons of the skin during embryogenesis and in adulthood, and possibly during cutaneous inflammation. This study examined NGF content and sprouting of nerves during the elicitation phase of contact allergy in human skin. Skin biopsies from patients (n=14) undergoing patch-testing were taken from positive test sites and control back skin 96 h after antigen application. NGF content was measured by enzyme-linked immunofluorescence assay. Immunohistochemistry was performed for protein gene product 9.5 (PGP9.5), a marker that stains all neuronal elements, and growth-associated protein 43 (GAP43), a marker for axonal growth cones. The NGF content was significantly increased in lesional skin in comparison with normal skin (4.2+/-0.6 pg to 2.9+/-0.5 pg NGF per mg wet weight). The length of epidermal PGP9.5-immunoreactive (ir) fibers in lesional skin significantly increased from 3.4+/-0.9 mm in normal skin to 5.3+/-1.0 mm in contact eczema, whereas dermal fibers were unaltered (11.1+/-2.7 mm vs 9.5+/-2.1 mm, respectively). GAP43-ir nerve endings were significantly increased in both epidermis (1.6+/-0.3 mm to 2.6+/-0.4 mm) and dermis (0.5+/-0.1 mm to 1.8+/-0.2 mm) in contact eczema. Thus, we have provided evidence for an NGF-mediated nerve-fiber sprouting in human contact eczema. This may have a functional impact on skin-associated immune cells, in particular mast cells and Langerhans cells.     

Intrapulmonary delivery of bone marrow-derived mesenchymal stem cells improves survival and attenuates endotoxin-induced acute lung injury in mice

Recent in vivo and in vitro work suggests that mesenchymal stem cells (MSC) have anti-inflammatory properties. In this study, we tested the effect of administering MSC directly into the airspaces of the lung 4 h after the intrapulmonary administration of Escherichia coli endotoxin (5 mg/kg). MSC increased survival compared with PBS-treated control mice at 48 h (80 vs 42%; p < 0.01). There was also a significant decrease in excess lung water, a measure of pulmonary edema (145 +/- 50 vs 87 +/- 20 microl; p < 0.01), and bronchoalveolar lavage protein, a measure of endothelial and alveolar epithelial permeability (3.1 +/- 0.4 vs 2.2 +/- 0.8 mg/ml; p < 0.01), in the MSC-treated mice. These protective effects were not replicated by the use of further controls including fibroblasts and apoptotic MSC. The beneficial effect of MSC was independent of the ability of the cells to engraft in the lung and was not related to clearance of the endotoxin by the MSC. MSC administration mediated a down-regulation of proinflammatory responses to endotoxin (reducing TNF-alpha and MIP-2 in the bronchoalveolar lavage and plasma) while increasing the anti-inflammatory cytokine IL-10. In vitro coculture studies of MSC with alveolar macrophages provided evidence that the anti-inflammatory effect was paracrine and was not cell contact dependent. In conclusion, treatment with intrapulmonary MSC markedly decreases the severity of endotoxin-induced acute lung injury and improves survival in mice.     

Cell contact-mediated macrophage activation for antileishmanial defense. II. Identification of effector cell phenotype and genetic restriction

Host defense in cutaneous leishmaniasis, due to Leishmania tropica, is largely--if not exclusively--cell mediated. We observed in vitro that draining lymph node lymphocytes from L. tropica-infected C57BL/6 mice activate L. tropica-infected macrophages to kill the intracellular parasites (leishmanicidal effect). Because direct cell contact between lymphocytes and infected macrophages is required to achieve a maximum leishmanicidal effect, this effect cannot be attributed solely to lymphokines. Furthermore, because effector lymphocytes induced no detectable damage to infected macrophages, the effect also differs from conventional lymphocyte-mediated cytotoxicity. The present study identifies the phenotype of the effector lymphocyte and assesses the genetic restriction of the lymphocyte-macrophage interaction. Nylon wool column-enriched T lymphocytes from infected mice activate macrophages for antileishmanial effects; treatment of lymphocytes with anti-Thy-1.2 antibody plus complement abolishes this capacity. Furthermore, treatment with anti-Lyt-1 antibody plus complement (but not with anti-Lyt-2 plus complement) likewise abolishes the effector capacity of the lymphocytes. Parallel studies reveal that the percentage of Lyt-1+2- cells present in draining lymph nodes increases during the course of infection and reaches a peak with the onset of spontaneous resolution of the infection. Syngeneic, but not allogeneic, combinations of lymphocytes and infected macrophages result in macrophage activation. Furthermore, treatment of cells with appropriate anti-Ia monoclonal antibody abrogates the antileishmanial effects. These results indicate that Lyt-1+2- lymphocytes obtained from mice with spontaneously healing L. tropica infections can exert antileishmanial effects in vitro. This effect is genetically restricted--most likely to the I region of the MHC--and requires direct cell contact. The temporal relationship between the appearance of these effector lymphocytes in mice and the onset of disease resolution argues that they may also exert these antileishmanial effects in vivo.     

Effect of macrophage decay products on the incorporation of H3-thymidine into pulmonary cells in rats

3H-thymidine is injected to Wistar rats 60 min before their sacrifice, that is performed 24 h after intratracheal administration of isotonic solution of natrium chloride (control), and in the test animals--24 or 72 h after similar injection of macrophage decay products (MDP). The MDP are prepared by freezing-thawing of syngenic peritoneal macrophages repeated 5 times in the dose corresponding to 10(8) of the destroyed cells per 100 g of body mass. During the first period after MDP injection the labelling index of macrophages, histiocytes and cells of the alveolar epithelium increases up to 4.07 +/- 0.21%, during the second--up to 3.34 +/- 0.17% (in the control--1.90 +/- 0.18%). The results obtained are discussed according to modern ideas on the role of the interstitial cell pool as an immediate source for mobilization of alveolar macrophages, and together with the data previously accumulated, on the role of MDP in the autoregulatory control of various links of the macrophagal pulmonary reaction.     

Macrophage-mediated in vitro sensitization of lymphocytes

Summary Antigen-fed macrophages were able to induce specific sensitization of unprimed syngeneic lymphocytes in vitro. The sensitized lymphocytes caused specific injury to target cells that carried the relevant antigens. In the present study, we investigated the in vivo activity of lymphocytes sensitized by antigen-fed macrophages. Mouse spleen cells were sensitized by macrophages that had been exposed to the radiation leukemia virus (RadLV). The sensitized lymphocytes, which were enriched for T-cells, were injected to syngeneic normal recipients and 4 days later the mice were challenged with RadLV-induced lymphoma cells. By following tumor growth and survival of mice, we have found that the sensitized lymphocytes protected the recipient mice against lymphoma development if injected 4 days before the tumor cells. The protective activity of the sensitized lymphocytes was radioresistant, but they could not protect irradiated hosts. It is suggested that macrophagemediated in vitro sensitization of lymphocytes induces initiator cells that can protect the recipient host by recruitment of a defensive immune response.     

Adhesion molecules on peripheral blood lymphocyte subpopulations in the elderly

Adhesion molecules, such as CD49d, CD50 and CD62L, have important roles in many adhesive interactions involving cells of the immune system. Since it has been shown that many immunological alterations are present in aged subjects, we studied, by means of triple colour whole blood immunostaining and multiparametric flow cytometry, the expression and intensity level (MFI) of these molecules on peripheral blood lymphocyte subpopulations from 23 healthy elderly subjects and 13 young controls. In the elderly a decrease in total peripheral blood lymphocytes bearing CD62L antigen was observed (39 +/- 13% vs 63 +/- 6% and 745 +/- 312/mm3 vs 1,393 +/- 407/mm3; p<0.001), whereas the numbers of lymphocytes expressing CD49d and CD50 antigens were comparable in aged and young subjects. In addition, CD50 and CD62L MFI values on total peripheral blood lymphocytes were higher in elderly than in young subjects (5.23 +/- 1.03 vs 4.18 +/- 0.44, p = 0.001 and 2.60 +/- 0.35 vs 2.21 +/- 0.40, p = 0.005 respectively) while the intensity expression of CD49d was unchanged. The percentages and absolute numbers of T and B lymphocytes expressing CD62L were decreased in elderly compared to young subjects (CD62L+CD3+: 43 +/- 15% vs 66 +/- 9% and 581 +/- 257/mm3 vs 1,028 +/- 418/mm3, p<0.001; CD62L+CD19+: 78 +/- 12% vs 90 +/- 4%, p < 0.005 and 103 +/- 64/mm3 vs 207 +/- 98, p < 0.001). A decrease in the proportion of CD62L bearing NK cells was also observed in the elderly (25 +/- 14% vs 46 +/- 24%, p<0.005), although their absolute number was unchanged. No significant differences were detected in the proportion of T, B and NK lymphocytes expressing CD49d and CD50 antigens and only the absolute numbers of B cells expressing these adhesion molecules were lower in elderly (CD49d+CD19+: 121 +/- 71/mm3 and CD50+CD19+: 107 +/- 73/mm3) compared to young donors (CD49d+CD19+: 248 +/- 112/mm3 and CD50+CD19+: 235 +/- 120/mm3, p < 0.001). Moreover, the intensity of adhesion molecule expression was differentially modulated in the elderly depending on the specific lymphocyte cell population considered. The densities of CD49d, CD50 and CD62L antigens on B and NK lymphocytes from the two age groups were not different; on the contrary, T lymphocytes from elderly donors exhibited increased CD49d (1.69 +/- 0.09 vs 1.62 +/- 0.07, p < 0.05), CD50 (4.98 +/- 1.16 vs 3.77 +/- 0.46, p < 0.001) and CD62L (2.26 +/- 0.38 vs 1.99 +/- 0.37, p < 0.05) MFI values compared to young donors.     

The cellular composition of the bronchoalveolar washing in experimental anthracosis

Bronchoalveolar lavage (BAL) was performed in albino random-bred adult male rats with pneumoconiosis. Fibrotic reaction in the lungs was induced by inhalation coal dust during 6 months. BAL comprised 90.9 +/- 1.2% of macrophages; 4.4 +/- 0.8% of neutrophils and 4.5 +/- 1.0% of lymphocytes. The total cell number in BAL was higher (over 59%) in animals with pneumoconiosis. The number of cells on alveolar surface of the lungs was also higher. Fibrotic reaction in the lungs is probably directly related with the increased number of vital macrophages in the lung.     

Kinetics and characteristics of murine macrophage-lymphocyte interaction in presence of PHA: appearance of multinucleated giant cells in vitro

The appearance of cellular associations between macrophages and lymphocytes--which we have denominated macrophage-lymphocyte rosettes--and their kinetic formation in the presence of phytohemagglutinin (PHA) have been studied in B10 A (4R) mice. The greatest number of macrophage-lymphocyte rosettes was found from 6 to 12 hours after incubation with PHA. During this time, 42.38 +/- 10.70 of the total number of macrophages had lymphocytes attached to their membranes. This percentage decreased to 17.33 +/- 2.07% after 24 hours. The activation of macrophages after PHA treatment was tested by the phagocytic capacity of these cells. This activity increased significantly 24 hours after incubation. In our assay, an increase in the appearance of multinucleated giant cells when compared to controls was also observed. When the macrophages were lymphocyte depleted, the appearance of the multinucleated giant cells was significantly lower. The kinetics for these formations are also discussed.     

Cutting edge: CD8 T cell-mediated demyelination is IFN-gamma dependent in mice infected with a neurotropic coronavirus

Mice infected with the murine coronavirus, mouse hepatitis virus, strain JHM (MHV) develop an immune-mediated demyelinating encephalomyelitis. We showed previously that adoptive transfer of MHV-immune splenocytes depleted of either CD4 or CD8 T cells to infected RAG1(-/-) recipients (mice deficient in recombination activation gene 1) resulted in demyelination. Herein we show that transfer of CD8 T cell-enriched splenocytes from MHV-immune IFN-gamma(-/-) donors resulted in a substantial decrease in demyelination (4.8% of the white matter of the spinal cord compared with 26.3% in those receiving cells from C57BL/6 donors). Similar numbers of lymphocytes were present in the CNS of recipients of either C57BL/6 or IFN-gamma(-/-) CD8 T cells, suggesting that IFN-gamma was not crucial for lymphocyte entry into the CNS. Rather, IFN-gamma was critical for optimal activation or migration of macrophages or microglia into the white matter in the context of CD8 T cell-mediated demyelination.     

Generation of specific helper cells and suppressor cells in vitro for the IgE and IgG antibody responses.

Normal splenic lymphocytes from BDF1 mice were cultured on ovalbumin (OA)-bearing syngeneic peritoneal adherent cells for 5 days and their subsequent helper function was tested by an adoptive transfer technique. Lymphocytes harvested from the culture were mixed with DNP-KLH-primed spleen cells and transferred into irradiated syngeneic mice followed by challenge with DNP-OA. The results showed that the cultured lymphocytes has helper function for both IgE and IgG anti-DNP antibody responses. Depletion of mast cells and T cells in the peritoneal adherent cell preparations did not affect the generation of helper cells in the culture. The helper function of the cultured lymphocytes was abolished by the treatment with anti-theta antiserum and complement and was specific for ovalbumin. The OA-specific helper T cells were generated in vitro by the culture of a T cell-rich fraction of normal spleen on T cell-depleted OA-bearing peritoneal cells. If the normal splenic lymphocytes or T cell-rich fraction were cultured with 10 mug/ml of OA in the absence of macrophages, cultured lymphocytes lacked helper function. The transfer of splenic lymphocytes or splenic T cells cultured with soluble OA to normal non-irradiated mice, however, suppressed both IgG and IgE antibody responses of the recipients to subsequent immunization with DNP-OA. The suppressor cells were sensitive to anti-theta antiserum and complement and their activity was specific for OA. The cultured cells transferred into normal mice did not suppress anti-hapten antibody response to DNP-KLH. Normal lymphocytes cultured on OA-bearing macrophages and had helper function in adoptive transfer experiments failed to suppress antibody response of non-irradiated recipients to DNP-OA. The results indicate that OA-bearing macrophages primed T cells and generated helper T cells, whereas the culture of normal lymphocytes with soluble OA in the absence of macrophages generated suppressor T cells.     

Enhanced ABCG1 expression increases atherosclerosis in LDLr-KO mice on a western diet

ABCG1 promotes cholesterol efflux from cells, but ABCG1(-/-) bone marrow transplant into ApoE(-/-) and LDLr(-/-) mice reduces atherosclerosis. To further investigate the role of ABCG1 in atherosclerosis, ABCG1 transgenic mice were crossed with LDLr-KO mice and placed on a high-fat western diet. Increased expression of ABCG1 mRNA was detected in liver (1.8-fold) and macrophages (2.7-fold), and cholesterol efflux from macrophages to HDL was also increased (1.4-fold) in ABCG1xLDLr-KO vs. LDLr-KO mice. No major differences were observed in total plasma lipids. However, cholesterol in the IDL-LDL size range was increased by approximately 50% in ABCG1xLDLr-KO mice compared to LDLr-KO mice. Atherosclerosis increased by 39% (10.1+/-0.8 vs 6.1+/-0.9% lesion area, p=0.02), as measured by en face analysis, and by 53% (221+/-98 vs 104+/-58x10(3)microm(2), p =0.01), as measured by cross-sectional analysis in ABCG1xLDLr-KO mice. Plasma levels for MCP-1 (1.5-fold) and TNF-alpha (1.2-fold) were also increased in ABCG1xLDLr-KO mice. In summary, these findings suggest that enhanced expression of ABCG1 increases atherosclerosis in LDLr-KO mice, despite its role in promoting cholesterol efflux from cells.     

Glucose metabolism by lymphocytes, macrophages, and tumor cells from Walker 256 tumor-bearing rats supplemented with fish oil for one generation

Here we investigated the effect of lifelong supplementation of the diet with coconut fat (CO, rich in saturated fatty acids) or fish oil (FO, rich in n-3 polyunsaturated fatty acids) on tumor growth and lactate production from glucose in Walker 256 tumor cells, peritoneal macrophages, spleen, and gut-associated lymphocytes. Female Wistar rats were supplemented with CO or FO prior to mating and then throughout pregnancy and gestation and then the male offspring were supplemented from weaning until 90 days of age. Then they were inoculated subcutaneously with Walker 256 tumor cells. Tumor weight at 14 days in control rats (those fed standard chow) and CO supplemented was approximately 30 g. Supplementation of the diet with FO significantly reduced tumor growth by 76%. Lactate production (nmol h(-1) mg(-1) protein) from glucose by Walker 256 cells in the group fed regular chow (W) was 381.8 +/- 14.9. Supplementation with coconut fat (WCO) caused a significant reduction in lactate production by 1.6-fold and with fish oil (WFO) by 3.8-fold. Spleen lymphocytes obtained from W and WCO groups had markedly increased lactate production (553 +/- 70 and 635 +/- 150) when compared to non-tumor-bearing rats ( approximately 260 +/- 30). FO supplementation reduced significantly the lactate production (297 +/- 50). Gut-associated lymphocytes obtained from W and WCO groups increased lactate production markedly (280 +/- 31 and 276 +/- 25) when compared to non-tumor-bearing rats ( approximately 90 +/- 18). FO supplementation reduced significantly the lactate production (168 +/- 14). Lactate production by peritoneal macrophages was increased by tumor burden but there was no difference between the groups fed the various diets. Lifelong consumption of FO protects against tumor growth and modifies glucose metabolism in Walker tumor cells and lymphocytes but not in macrophages.