HIV-1 infection of human T lymphocytes results in enhanced alpha 5 beta 1 integrin expression.

Altered T cell adherence after human immunodeficiency virus 1 (HIV-1) infection may contribute to viral pathogenesis in the acquired immune deficiency syndrome. To address this hypothesis, we assessed mechanisms of T cell adherence to extracellular matrix proteins in vitro. We found that after HIV-1 infection, both chronically infected H9 CD4+ T cells and acutely infected primary peripheral blood lymphocytes acquired the ability to adhere to the extracellular matrix glycoprotein fibronectin, to a lesser extent to type IV collagen and laminin, but not to type I collagen. H9 cells chronically infected with two of the three HIV-1 strains studied showed approximately a sevenfold increase in attachment to fibronectin, while the same cells infected with the human retrovirus HIV-2 did not. Adhesion was accompanied by changes in morphology, including marked spreading and increased filopodia. These alterations were not blocked by the protein kinase C inhibitor H-7, which did inhibit TPA-induced T cell attachment to fibronectin. Monoclonal antibodies against both the alpha 5 and the beta 1 subunits of the classical fibronectin receptor as well as an Arg-Gly-Asp (RGD) peptide inhibited attachment, whereas anti-alpha 4 monoclonal antibodies and the CS1 peptide did not. Binding to collagen IV was also inhibited by the anti-beta 1 monoclonal antibody, but not the other antibodies. Cells metabolically labeled with [35S]methionine and analyzed by immunoprecipitation with polyclonal anti-beta 1 integrin antibody showed a 2.5-fold increase in integrin synthesis in infected cells compared to uninfected controls. This increase in synthesis was associated with an increase in cell surface expression of both alpha 5 and beta 1 integrins by FACS (registered trademark of Becton Dickinson for a fluorescence-activated cell sorter) analysis. Enhanced expression of integrins such as alpha 5 beta 1 may cause T cell adherence to a variety of tissues, where released viral gene products may induce some of the tissue-specific manifestations of HIV-1 infection.

Functional role of thromboxane production by acutely rejecting renal allografts in rats.

We investigated the role of thromboxane in mediating the reduction in renal function and renal blood flow characteristic of acute renal allograft rejection. We transplanted kidneys from Lewis rats to Brown-Norway recipients. By the third day after transplantation, histologic changes that were consistent with cellular rejection occurred in the kidney. These changes were associated with a moderate reduction in renal function. By day 6, histologic changes of rejection were advanced and included interstitial and perivascular infiltration by mononuclear cells. The clearances of inulin and para-aminohippuric acid were also markedly reduced. As renal function deteriorated, thromboxane B2 (TXB2) production by ex vivo perfused renal allografts increased progressively from 2 to 6 d after transplantation. However, prostaglandin (PG) E2 and 6-keto PGF1 alpha production remained essentially unchanged. There was a significant inverse correlation between the in vivo clearance of inulin and the log of ex vivo TXB2 production. Infusion of the thromboxane synthetase inhibitor UK-37248-01 into the renal artery of 3-d allografts significantly decreased urinary TXB2 excretion and significantly increased renal blood flow (RBF) and glomerular filtration rate (GFR). Although renal function improved significantly after the acute administration of UK-37248-01, GFR and RBF did not exceed 33 and 58% of native control values, respectively. In other animals, daily treatment with cyclophosphamide improved the clearances of inulin and para-aminohippuric acid and reduced thromboxane production by 6-d renal allografts. These studies demonstrate that histologic evidence of rejection is associated with increased renal thromboxane production. Inhibition of thromboxane synthetase improves renal function in 3-d allografts. Cytotoxic therapy improves renal function, reduces mononuclear cell infiltration, and decreases allograft thromboxane production. Thus, the potent vasoconstrictor thromboxane A2 may play a role in the impairment of renal function and renal blood flow during acute allograft rejection.

Bradykinin stimulation of oxidative metabolism in renal cortical tubules from rabbit. Possible role of arachidonic acid.

Vasoactive peptides may have direct effects on both renal vasculature and renal tubules. In this study, we examined the direct and immediate effects of bradykinin on oxygen consumption by suspensions of cortical tubules from rabbit kidney. Bradykinin (10(-11) to 10(-7) M) stimulated oxygen consumption rates (QO2) in a dose-dependent manner with a maximal increase of +0.80 +/- 0.13 nmol X mg protein-1 X min-1. This stimulation was prevented by calcium-free media or by the addition of inhibitors of calcium transport, calcium-calmodulin complex formation, Na,K-ATPase activity, mitochondrial respiration, and phospholipase activity. Addition of bradykinin increased the ADP and AMP contents of cortical tubules without changing the ATP content. These data indicate that bradykinin stimulates ATP use and Na,K-ATPase activity. We also examined the effects of exogenous arachidonic acid on QO2 in cortical tubules. Acute additions of arachidonic acid stimulated QO2 at low concentrations (10(-8) to 10(-6) M) and uncoupled mitochondrial respiration at high concentrations (10(-5) M). The effect of arachidonic acid on adenosine nucleotide content was dose-dependent and indicated increased use of ATP. Bradykinin increased QO2 in the presence of low concentrations of arachidonic acid (10(-11) to 10(-9) M), but had no further effect on QO2 in the presence of higher concentrations of arachidonic acid (10(-8) to 10(-6) M). Bradykinin stimulation of QO2 was not prevented by inhibition of cyclooxygenase activity with indomethacin but was prevented by inhibition of lipoxygenase-like activity with nordihydroguariaretic acid. These results suggest that the bradykinin effect on QO2 may be mediated by arachidonic acid release and subsequent metabolism.

Water deprivation stimulates transforming growth factor-beta 2 accumulation in the juxtaglomerular apparatus of mouse kidney.

Transforming growth factor-beta (TGF-beta) modulates the growth and differentiation of many cells and often functions in an autocrine or paracrine fashion. The myoepithelial cells of the renal juxtaglomerular apparatus (JGA) synthesize and secrete renin. Under conditions which chronically stimulate renin production, the JGA undergoes hypertrophy and hyperplasia. The molecular factors responsible for these changes in the JGA have not been identified. In the present study, plasma renin activity was stimulated in the mouse by water deprivation. Using immunoperoxidase staining with specific antibodies against TGF-beta 1, beta 2, and beta 3, we found increased TGF-beta 2 accumulation in the JGA and interlobular arteries. Immunostaining with renin antiserum demonstrated colocalization of TGF-beta 2 and renin. TGF-beta 1 and beta 3 expression was not different between control and water-deprived mice. Our results suggest that in the setting of water deprivation, TGF-beta 2 is localized in a manner which would allow it to act either as a growth factor for or as a phenotypic modulator of the JGA and renal arterioles.

Nephropathy in human immunodeficiency virus-1 transgenic mice is due to renal transgene expression.

HIV-associated nephropathy (HIVAN) is a progressive glomerular and tubular disease that is increasingly common in AIDS patients and one of the leading causes of end stage renal disease in African Americans. A major unresolved issue in the pathogenesis of HIVAN is whether the kidney disease is due to renal cell infection or a "bystander" phenomenon mediated by systemically dysregulated cytokines. To address this issue, we have used two different experimental approaches and an HIV-1 transgenic mouse line that develops a progressive renal disease histologically similar to HIVAN in humans. In the murine model, kidney tissue expresses the transgene and in heterozygous adults, renal disease develops shortly thereafter. We demonstrate by terminal deoxynucleotide transferase-mediated dUTP-biotin nick-end labeling assay that similar to the disease in humans, apoptosis of renal tubular epithelial cells is a component of the molecular pathogenesis. To determine whether apoptosis is due to transgene expression or environmental factors, we treated fetal kidney explants (normal and transgenic) with UV light to induce transgene expression. Apoptosis occurred in transgenic but not normal littermates after stimulation of transgene expression. To confirm a direct effect of HIV expression on the production of HIVAN, we transplanted kidneys between normal and transgenic mice. HIVAN developed in transgenic kidneys transplanted into nontransgenic littermates. Normal kidneys remained disease free when transplanted into transgenic littermates. Thus, the renal disease in the murine model is intrinsic to the kidney. Using two different experimental approaches, we demonstrate a direct effect of transgene expression on the development of HIVAN in the mouse. These studies suggest that in humans, a direct effect of HIV-1 expression is likely the essential cause of HIVAN, rather than an indirect effect of cytokine dysregulation.

A novel sequence in the type IV collagen promoter binds nuclear proteins from Engelbreth-Holm-Swarm tumor.

The production of extracellular matrix proteins is an important element of tumor formation, and alterations in matrix protein metabolism may be critical to the process of tumor metastasis. Abundant expression of type IV collagen, the major structural protein of the basement membrane, is characteristic of the Engelbreth-Holm-Swarm (EHS) mouse sarcoma. In the present study, we evaluated mechanisms of transcriptional regulation of type IV collagen genes by analysing nuclear factors that bind to the promoter region. Gel mobility-shift assays indicated that specific proteins from EHS tumor bound the promoter and generated several unique shift patterns. The specific sequences to which these proteins bound were determined using DNAase I protection assays. DNA-binding proteins protected two regions from DNAase I digestion. The first region was similar to a GC box, the binding site for the transcription factor Sp1. The other footprint was a 30-bp region that contained the novel sequence motif, 'CCCTCCC' present in several other extracellular matrix promoters. Nuclear extracts isolated from tissues that variably express type IV collagen bound to this protected sequence with distinctly different shift patterns. Furthermore, in highly expressing tissues, unlabeled oligonucleotides containing the 'CCCTCCC' motif effectively inhibited nuclear protein binding with the entire promoter. Thus, it is likely that a novel protein or protein complex binds to these sequences. Furthermore, these sequences appear to be unique to the genes that encode basement membrane proteins, suggesting a specific role in their regulation.

Transgenic models of human immunodeficiency virus type-1.

Transgenic models have provided significant insights into HIV-1 pathogenesis, particularly with regards to Kaposi's sarcoma. HIV-associated nephropathy, the tissue-restricted expression of CNS strains of HIV-1, and the function of Nef in vivo. Both multigenic and single gene constructs have contributed to our understanding of HIV-1-induced diseases. While failing to provide models suitable for vaccine development, these transgenic models have provided great insight into HIV pathogenesis and may yet provide a means for the development and testing of molecular based therapies for AIDS.

Inhibition of HIV-1 expression by HIV-2.

HIV-1 and HIV-2 are co-endemic in certain geographic areas. HIV-2 is more weakly pathogenic than HIV-1, and progression to AIDS occurs less frequently and over a longer period of time. Recent epidemiologic studies suggest that individuals infected with HIV-2 have a lower risk of HIV-1 infection. Both immune mechanisms and various modes of viral interference have been proposed to account for these results. Our findings, described in this paper, suggest that HIV-2 inhibits HIV-1 replication. To study the molecular interactions between HIV-1 and HIV-2, proviral clones were transfected alone or in combination into the human T cell line CEM. LTR-CAT indicator constructs were included for the purpose of monitoring viral promoter activity. Viral replication in transfected cells was monitored by p24 antigen capture assay of cell culture supernatants and Western blot analysis of cell extracts. HIV-2 inhibited HIV-1 replication as determined by intracellular and extracellular p24 antigen levels. Similar results were obtained with simultaneous virus infection using HIV-1 and HIV-2, rather than transfections of proviral DNA. Using cotransfection of HIV-1 and HIV-2 LTR indicator gene constructs, the mechanism of inhibition was found to be suppression of the HIV-1 LTR by HIV-2. The inhibitory effect of HIV-2 is not due to Tat-2, but appears to discriminate between the HIV-1 and HIV-2 LTRs based on differences in the Tat activation response element, TAR. These results suggest both a molecular mechanism for HIV-2 interference with HIV-1 replication and a potential molecular approach to therapy.

Rapid blood pressure control with minoxidil: acute and chronic effects on blood pressure, sodium excretion, and the renin-aldosterone system.

Changes in blood pressure, heart rate, electrolyte excretion, and the renin-angiotensin-aldosterone system were monitored before and after minoxidil was added to a regimen of a diuretic and propranolol hydrochloride in 12 severely hypertensive patients. None required more than 40 mg of minoxidil daily for control. On a constant intake, urinary sodium excretion decreased, while urinary potassium excretion remained stable. Heart rate, body weight, and plasma volume increased, while creatinine clearance did not change. Although plasma renin activity increased fourfold, the plasma aldosterone concentration did not increase. Six subjects were restudied after two months of minoxidil treatment. Although blood pressure control continued to be excellent in these subjects, plasma renin values and plasma volume had returned to pretreatment levels. These studies suggest that minoxidil rapidly and effectively lowers blood pressure. Although sodium retention accompanies minoxidil administration acutely, the effect is independent of aldosterone and may be transient.

Transgenic models of HIV-1.

Transgenic technology has been very successful at providing insights into possible processes involved in HIV-induced pathogenesis. The availability of these small animal models for the study of HIV-related syndromes including KS, epidermal proliferative lesions, HIV-associated nephropathy, AIDS-related growth failure and cachexia may well facilitate the development of novel therapies for these complications. Other phenotypes created in mice, such as cataracts and hepatic cancer [59], may not have human analogies but may still provide insight into pathogenesis. Thus, transgenic models have already provided resources to study many manifestations of AIDS and others are likely to be developed. The optimal strategy for designing future transgenic animals, however, is less clear. No transgenic mouse model has been generated to date that will provide an avenue for vaccine development. This advance awaits the further discovery of the host factors that facilitate the virus replicative cycle in humans and a better understanding of these pathways in the mouse. For the development of molecular-based therapy, however, the currently available models may well be adequate to test molecular inhibitors of transcription [7,60,61] and post-transcriptional processing of viral mRNA [62]. Whether single or multigenic constructs under the control of the LTR are better or worse for this purpose is a debatable issue. Transgenic technology may yet make an additional contribution to the development of molecular therapy for AIDS. The best method of demonstrating that a gene therapeutic strategy is safe to administer to patients has not been determined. By introducing potentially therapeutic constructs into mice as transgenes, their safety can be assessed in many different cell types in vivo, analogous to toxicological testing in rodents for systemically administered drugs. Thus, transgenic technology has already provided insights into the pathogenesis of HIV-1. While it has not yet proven its utility for vaccine development, transgenic technology holds the promise of being an active participant in the development of both safe and effective gene therapy approaches for the treatment of AIDS.

Regulation of renal 25-hydroxyvitamin D-1-hydroxylase activity in the mouse after uninephrectomy.

Although renal hypertrophy occurs rapidly after uninephrectomy, restoring the majority of renal excretory function, it remains unknown whether similar compensatory mechanisms maintain 1,25-dihydroxyvitamin D production (and calcium homeostasis). To address this issue we compared plasma calcitriol levels and renal 25-hydroxyvitamin D (25OHD)-1-alpha-hydroxylase activity (in remnant kidneys) of mice at various times after uninephrectomy to similar observations obtained in sham-operated age- and sex-matched controls. At all times postoperatively, the uninephrectomized mice sustained plasma 1,25-dihydroxyvitamin D levels no different from those of shams. Maintenance of calcitriol production occurred secondary to a significant increment of renal 25OHD-1 alpha-hydroxylase activity (per mg DNA) 1-3 days after surgery when renal mass/function remained markedly depressed. In contrast, 10 and 21 days postoperatively, when hypertrophy was complete, enhanced enzyme function was no longer apparent. Throughout this period a significant inverse linear correlation existed between renal 25OHD-1 alpha-hydroxylase and the renal mass as well as glomerular filtration rate and renal blood flow. The variance in enzyme activity resulted in maintenance of a stable renal 25OHD-1 alpha-hydroxylase (per animal or total kidney mass) at all times investigated postuninephrectomy. Such compensatory regulation of vitamin D metabolism after unilateral kidney extirpation may be an important factor contributing to the low morbidity/mortality in the renal donor.

Double-blind, placebo-controlled trial of potassium chloride in the treatment of mild hypertension.

Epidemiological and experimental data suggest blood pressure-lowering effects of dietary potassium. A randomized, double-blind clinical trial was used to assess blood pressure response to orally administered potassium, 120 mEq/day, and to placebo in 101 adults with mild hypertension. Blood pressure was measured with a random-zero sphygmomanometer every 2 weeks of this 8-week trial. Systolic blood pressure in the potassium-treated group decreased by 6.4 +/- 13.7 (SD) mm Hg (p less than or equal to 0.025) compared with 0.11 +/- 13.0 mm Hg in the placebo-treated group (p = 0.96). Diastolic blood pressure in the potassium-treated group decreased by 4.1 +/- 8.3 mm Hg (p less than or equal to 0.05) compared with a 1.6 +/- 6.5 mm Hg decrease in placebo-treated subjects (p = 0.09). Baseline blood pressure of potassium-treated subjects was unexpectedly higher than that of controls. After correcting for baseline variation, blood pressure still decreased 3.4/1.8 mm Hg more in potassium recipients than in placebo recipients (p = 0.14 and 0.24, respectively). Blood pressure decreased by 19/13 mm Hg in five blacks taking potassium versus a 1/0 mm Hg increase in seven blacks taking placebo. Compliance with the potassium regimen was 91.5% by pill count; only one subject discontinued treatment because of side effects. In conclusion, 120 mEq/day of microencapsulated potassium chloride was well tolerated in adults with mild hypertension. An antihypertensive effect of potassium cannot be ruled out despite the fact that there was no statistically significant difference between potassium-treated and placebo-treated subjects after adjustment for differences in baseline blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Prospective analysis of strategies for diagnosing renovascular hypertension.

Renovascular hypertension is a potentially curable form of high blood pressure. However, it is unclear how best to select patients who are likely to have renovascular hypertension, what diagnostic strategy to use in these selected patients, and how to predict the hemodynamic significance of a renal artery stenosis. We determined the prevalence of renovascular hypertension in adults who exhibited suggestive clinical features. In these clinically selected patients, we then determined the test characteristics of various diagnostic and potential screening tests. Renovascular hypertension was diagnosed if correction of renal artery stenosis resulted in decreased blood pressure. Of the 66 hypertensive adults evaluated, 11 (16.7%) had renovascular hypertension. Captopril-stimulated peripheral renin activity detected renovascular hypertension with 73% sensitivity, 72% specificity, 38% positive predictive value, and 92% negative predictive value. Less optimal combinations of sensitivity and specificity were found for differential glomerular filtration rate renography, differential effective renal plasma flow renography, and selective renal vein renin ratios, each performed after a single dose of captopril. Intravenous digital subtraction renal angiography detected all patients with renovascular hypertension and was normal in 71% of patients with essential hypertension. To evaluate potential screening tests for renovascular hypertension, we calculated predictive values applied to a low prevalence population. If the observed sensitivities and specificities apply to a population with 5% prevalence of renovascular hypertension, captopril-stimulated peripheral renin would have a positive predictive value of 12% and a negative predictive value of 98%. In 16 patients with known renal artery stenosis, neither the captopril-stimulated renal vein renin ratio nor captopril-stimulated differential renography accurately predicted blood pressure response to correction of the stenosis. We conclude that clinical criteria can identify a subgroup with 16.7% prevalence of renovascular hypertension. In this high prevalence group, intravenous digital subtraction renal angiography will identify virtually all patients with renovascular hypertension, and a normal study will be sufficient to exclude renovascular hypertension. In unselected hypertensive patients, screening with captopril-stimulated peripheral renin activity may be the most useful and efficient procedure for identification of patients with renovascular hypertension. Functional tests do not accurately predict the hemodynamic significance of a renal artery stenosis.

Similar prevalence of renovascular hypertension in selected blacks and whites.

Renovascular hypertension is a potentially curable form of high blood pressure that is thought to be extremely rare among blacks. We demonstrate, however, that in a clinically selected population, the prevalence of renovascular hypertension is similar in blacks and whites. We prospectively evaluated 167 hypertensive subjects who had one or more clinical features known to be associated with renovascular hypertension. All subjects had captopril-stimulated peripheral renin measurements and conventional renal arteriography. All significant renal artery stenoses (greater than 50% luminal narrowing) were treated with percutaneous transluminal angioplasty or surgery. Renovascular hypertension was diagnosed if there was a blood pressure response to interventional therapy, according to the criteria established by the Cooperative Study of Renovascular Hypertension. Of the total group evaluated, 24% (39 of 167) had renal artery stenosis and 14% (23 of 167) had renovascular hypertension. Renal artery stenosis or occlusion was found in 27% (26 of 97) of whites and 19% (13 of 67) of blacks (p = 0.27). Renovascular hypertension was diagnosed in 18% (17 of 97) of whites and 9% (6 of 67) of blacks evaluated (p = 0.25). Renovascular hypertension was associated with severe or refractory hypertension and with smoking, but there were no racial differences in these associations. Blacks with renovascular hypertension tended to have low captopril-stimulated peripheral renin activity. We conclude that blacks with clinical features suggestive of renovascular hypertension should be evaluated with angiography. Captopril-stimulated plasma renin may not be useful in detecting blacks with renovascular hypertension, but this and other potential screening tests require further evaluation.

Association of chronic thromboxane inhibition with reduced in situ cytotoxic T cell activity in rejecting rat renal allografts.

The development of allospecific cellular immunity during acute rat renal allograft rejection parallels alterations occurring in arachidonic acid metabolism, including increased production of the vasoconstrictor eicosanoid thromboxane A2 (TxA2). We have previously demonstrated that chronic inhibition of thromboxane synthetase is associated with improved renal allograft function as well as significant reductions in renal production and urinary excretion of Tx metabolites. In this study, we evaluated the effects of chronic administration of the specific Tx synthetase inhibitor OKY-046 on in situ and systemic alloimmune effector cell function. PVG (RT1c) strain rats were transplanted with fully allogeneic ACI(RT1a) kidneys, and intrarenal artery infusion of OKY-046 (50 micrograms/mg/min) or its saline vehicle was begun at the time of surgery utilizing an osmotic pump. Four days following transplantation, spleen cells and inflammatory cells eluted from the graft were tested. The frequency of antidonor precursor cytotoxic T cells (pCTL), as measured by limiting dilution assay, was consistently lower in allografts from OKY-046-treated animals (1/3146-1/5160) compared with vehicle treatment (1/661-1/1878), while no difference in pCTL ranges were seen in splenocytes from both groups. However, following short-term culture (10-15 days, lymphocytes from treated and control allografts were equally proficient in specifically lysing donor targets. Proliferative response to donor stimulators measured by mixed lymphocyte reaction assays were consistently greater in spleen cells than allograft eluate cells for both groups, but there were no significant differences between OKY and vehicle groups in terms of either splenocyte or allograft eluate proliferative responses. Immunohistologic labeling and flow cytometric analysis of renal allograft infiltrates showed similar percentages and distributions of immune cell populations in treated and control groups. These results suggest that Tx inhibition is capable of temporarily reducing cytotoxic T cell function in the local environment, which may partially account for the improved graft function seen.

Evidence that renal prostaglandin and thromboxane production is stimulated in chronic cyclosporine nephrotoxicity.

Previous reports suggest that cyclosporine (CsA) may have direct effects on arachidonic acid (AA) metabolism in several different tissues. However, the effects of CsA on renal eicosanoid production are unclear. Furthermore, the potential role of changes in renal prostaglandin and thromboxane metabolism in mediating CsA nephrotoxicity is not known. Therefore, in this study, we evaluated the effects of CsA toxicity on the production of AA metabolites by the kidney. In a postischemic, denervated rat model, CsA (50 mg/kg/day) administered for 12-14 days resulted in significant nephrotoxicity with marked decreases in both glomerular filtration rate and renal blood flow. This reduction in renal function was associated with an increase in the renal production of TXB2, PGE2, and 6-PGF1 alpha in vitro. Arachidonic acid significantly stimulated renal eicosanoid production above control values. Increased urinary excretion of TXB2, 2,3-dinorTXB2 (a major TXB2 metabolite), and 6-keto-PGF1 alpha also occurred in rats with CsA nephrotoxicity and reflected the increase in renal production of these eicosanoid products. In contrast, urinary PGE2 excretion was not increased in CsA toxic rats. Thus, CsA nephrotoxicity is associated with specific alterations in renal AA metabolism. Furthermore, alterations in AA metabolism may be important in modulating renal hemodynamics and excretory function in this model. These studies suggest that specific inhibition of vasoconstrictor products of AA metabolism might ameliorate the nephrotoxic effects of CsA.

Effect of dietary fish oil supplementation on eicosanoid production by rat renal allografts.

Acute renal allograft rejection is associated with significant alterations in renal arachidonic acid (AA) metabolism including increased production of the vasoconstrictor eicosanoid thromboxane (TX)A2. TX synthetase inhibition improves function of rejecting rat renal allografts but is difficult to accomplish pharmacologically. Therefore, we evaluated the potential use of dietary fish oil (FO) as a more practical method for reducing renal thromboxane production. We examined the effects of dietary FO supplementation on eicosanoid production and hemodynamic function of rat renal allografts. Donor and recipient rats were fed a fat-free diet supplemented with beef tallow (BT) or FO. After 6 weeks on the experimental diet, kidneys from ACI donors were transplanted into PVG recipients. Six days after transplant, renal function and eicosanoid production were measured. FO feeding resulted in significant alterations in eicosanoid production by renal allografts. There was a marked and generalized reduction in prostaglandin (PG) and TX production by allografts when both donor and recipient were fed a diet supplemented with fish oil. An intermediate reduction in production of PGE2 (and perhaps PGI2), but not TXB2, was observed when only the recipient was fed FO. Feeding FO to the donor alone had no effect on renal PG or TX production. These data suggest that both donor and recipient fatty acid pools contribute to AA metabolism during rejection. Unlike specific TX inhibition, the generalized inhibition of AA metabolism that occurred with FO feeding was not associated with improvement in function or morphology of allografts. However, potential benefit at earlier stages or in milder forms of rejection is possible and was not evaluated.

Evidence that pretransplant donor blood transfusion prevents rat renal allograft dysfunction but not the in situ cellular alloimmune or morphologic manifestations of rejection.

The effects of preoperative donor-specific blood transfusion (DSBT) on the physiologic, morphologic, and immunologic aspects of allograft responsiveness were evaluated in a rat renal transplant model, using the ACI (RT1a) into PVG (RT1c) high-responder strain combination. Indefinite graft survival (mean greater than 63 days) could be induced by DSBT administration alone. In comparison, animals receiving autologous blood transfusion (ABT) all died within 7 days posttransplantation. As assessed by clearance of inulin and paraaminohippurate, renal allograft function in DSBT-pretreated recipients at 6 days was equivalent to that of isograft recipients, and in contrast to the significant reduction seen in ABT treated rats. Likewise, thromboxane B2 (TXB2) production by ex-vivo-perfused allografts from DSBT-treated recipients was comparable to that of isografts, and significantly lower than that of allografts from ABT-treated rats. A significant inverse correlation was found between renal TXB2 production and inulin clearance. Despite these substantial differences in renal function and eicosanoid metabolism, morphologic evaluation of renal allografts from DSBT-enhanced and ABT-rejecting recipients at comparable time points showed equivalent histologic manifestations of rejection. In addition, immunohistologic labeling of renal allograft sections and fluorescence-activated cell sorter analysis of cells eluted from allografts showed the same phenotype and pattern of infiltrating T cell subsets in both groups. Specific antidonor cytotoxic T lymphocyte precursor (pCTL) frequencies of cells eluted from kidney grafts were equivalent in DSBT and ABT-pretreated animals, and both groups expressed significantly higher (but equivalent) pCTL frequencies in the kidneys than spleens. Comparisons of the lysis of PVG.R1 (RT1.Aa on a PVG background) and ACI targets indicated that cytotoxic responses from effector cells freshly eluted from DSBT and ABT kidneys were primarily directed against allogeneic class I major histocompatibility complex (MHC) specificities, whereas several long term T cell lines generated from 6-day kidney transplants of both groups expressed a predominant W3/25+ (T helper) phenotype and cytotoxic activity against donor specificities other than RT1.Aa class I MHC. Specific antidonor proliferative T lymphocyte (pPTL) precursor frequencies of cells eluted from renal allografts were also equivalent for both DSBT- and ABT-treated recipients, and the range of pPTL frequencies for allograft cell eluates was similar to that in spleens, regardless of the source of the transfusion.(ABSTRACT TRUNCATED AT 400 WORDS)

HIV-1 infection stimulates T cell invasiveness and synthesis of the 92-kDa type IV collagenase.

Tissue-specific localization of HIV-1-infected lymphoid cells may contribute to clinical manifestations of AIDS. Therefore we investigated the effect of HIV-1 infection on mechanisms of T lymphocyte invasion, a process required for movement of cells into and out of the circulation. In the present study, we demonstrate that HIV-1-infected human lymphocytes secrete increased amounts of the human 92-kDa type IV collagenase when compared to uninfected lymphocytes. Furthermore, HIV-1-infected lymphocytes degrade the extracellular matrix proteins collagen IV and fibronectin, and they are more invasive through a reconstituted basement membrane when compared to uninfected cells. The addition of either antibody to the 92-kDa collagenase or TIMP-2, a type IV collagenase inhibitor, abolishes invasive activity. These data suggest that HIV-1-infected lymphocytes express phenotypic characteristics that are consistent with an enhanced ability to leave the circulation and to localize in target tissues. Local viral infection or the release of viral proteins, cytokines, or proteolytic enzymes in tissues may contribute to pathogenesis.

Cutaneous disorders and viral gene expression in HIV-1 transgenic mice.

Patients infected with HIV-1 experience several hyperproliferative skin disorders, including seborrheic dermatitis, ichthyosis, and psoriasis. Transgenic mice carrying a subgenomic HIV-1 proviral construct lacking the gag and pol genes were found to develop proliferative epidermal lesions, manifested as diffuse epidermal hyperplasia in homozygous transgenic mice and benign papillomas in heterozygous transgenic mice. Nonpapillomatous skin from both homozygotes and heterozygotes expressed viral RNA, and the viral envelope protein gp120 was localized to the suprabasal keratinocyte. Papillomas contained increased amounts of both viral mRNA and envelope glycoprotein. Exposure of transgenic mice to doses of ultraviolet B (UV-B) irradiation that induced cutaneous injury increased viral gene expression and resulted in the development of papillomas within 14-21 days. Cutaneous injury induced by phenol and liquid nitrogen had similar effects. These data support a role for HIV-1 gene products in the pathogenesis of proliferative epidermal disorders associated with HIV-1 infection. Further, they suggest that the process of wound repair increases HIV-1 gene expression in this transgenic mouse model.