Topical becocalcidiol for the treatment of psoriasis vulgaris: a randomized, placebo-controlled, double-blind, multicentre study

BACKGROUND

Becocalcidiol is a vitamin D(3) analogue which has not caused hypercalcaemia or significant irritation in preclinical trials.

OBJECTIVES

To evaluate the efficacy and safety of two dosing regimens of becocalcidiol ointment (low dose = 75 microg g(-1) once daily for 8 weeks; high dose = 75 microg g(-1) twice daily for 8 weeks) in the treatment of plaque-type psoriasis.

METHODS

One hundred and eighty-five subjects with chronic plaque-type psoriasis affecting 2-10% of their body surface area took part in a multicentre, double-blind, parallel-group, vehicle-controlled, randomized controlled trial comparing topical application of placebo, becocalcidiol 75 microg g(-1) once daily (low dose) or becocalcidiol twice daily (high dose) for 8 weeks. Main outcomes included Physician's Static Global Assessment of Overall Lesion Severity (PGA) score; Psoriasis Symptom Severity (PSS) score; adverse events; and laboratory assessment.

RESULTS

In the intent-to-treat population at week 8, high-dose becocalcidiol was statistically superior to vehicle [P = 0.002; 95% confidence interval (CI) 6.7-32.2], with 16 of 61 (26%) subjects achieving a PGA score of clear or almost clear. Greater improvement in PSS score was seen with high-dose becocalcidiol than with vehicle, but this result did not quite achieve statistical significance (P = 0.052; 95% CI -16.2 to 0.1). In all groups, therapy was safe and well tolerated, with fewer subjects experiencing irritation than is reported in studies using calcipotriol.

CONCLUSIONS

Treatment with high-dose topical becocalcidiol for 8 weeks led to almost or complete clearing of moderate plaque-type psoriasis in over a quarter of patients. Therapy was safe and well tolerated.

Monokine induced by IFN-gamma is a dominant factor directing T cells into murine cardiac allografts during acute rejection

The use of chemokine antagonism as a strategy to inhibit leukocyte trafficking into inflammatory sites requires identification of the dominant chemokines mediating recruitment. The chemokine(s) directing T cells into cardiac allografts during acute rejection remain(s) unidentified. The role of the CXC chemokines IFN-gamma inducible protein 10 (IP-10) and monokine induced by IFN-gamma (Mig) in acute rejection of A/J (H-2(a)) cardiac grafts by C57BL/6 (H-2(b)) recipients was tested. Intra-allograft expression of Mig was observed at day 2 posttransplant and increased to the time of rejection at day 7 posttransplant. IP-10 mRNA and protein production were 2.5- to 8-fold lower than Mig. Whereas allografts were rejected at day 7-9 in control recipients, treatment with rabbit antiserum to Mig, but not to IP-10, prolonged allograft survival up to day 19 posttransplant. At day 7 posttransplant, allografts from Mig antiserum-treated recipients had marked reduction in T cell infiltration. At the time of rejection in Mig antiserum-treated recipients (i.e., days 17-19), intra-allograft expression of macrophage-inflammatory protein-1alpha, -1beta, and their ligand CCR5 was high, whereas expression of CXCR3, the Mig receptor, was virtually absent. Mig was produced by the allograft endothelium as well as by recipient allograft-infiltrating macrophages and neutrophils, indicating the synergistic interactions between innate and adaptive immune compartments during acute rejection. Collectively, these results indicate that Mig is a dominant recruiting factor for alloantigen-primed T cells into cardiac allografts during acute rejection. Although Mig antagonism delays acute heart allograft rejection, the results also suggest that the alloimmune response circumvents Mig antagonism through alternative mechanisms.

Free-floating cryostat sections for immunoelectron microscopy: Bridging the gap from light to electron microscopy

Frozen skin sections are routinely used for light microscopic immunohistochemical study of the skin basement membrane zone for two reasons: some skin basement membrane zone proteins are labile to routine chemical fixation, and skin is not amenable to vibratome sectioning. However, inherent limitations of conventional frozen sections, including compromised morphology and a requirement for glass slide-mounting, usually limit immunohistochemical study to the light microscopy level. In the present study, we introduce use of unfixed, free-floating cryostat sections for characterization of immunolocalizations of selected skin basement membrane proteins at both the light and electron microscopy level. The new procedure employs free-floating cryostat sections that can be processed as routine tissue specimens and can be subjected to a variety of special staining procedures including immunohistochemistry. Especially useful is the ease of progressive processing of the same tissue specimen from light microscopy to electron microscopy. In this regard, the method renders itself useful when results of immunolabeling experiments need to be elucidated quickly at histological and ultrastructural levels as required for diagnostic and accelerated investigative strategies.

A role for the angiotensin IV/AT4 system in mediating natriuresis in the rat

Angiotensin II (AngII) or Angiotensin IV (AngIV) was infused into the renal artery of anesthetized rats while renal cortical blood flow was measured via laser Doppler flowmetry. The infusion of AngII produced a significant elevation in mean arterial pressure (MAP) with an accompanying decrease in cortical blood flow, glomerular filtration rate (GFR), urine volume, and urine sodium excretion. The infusion of AngIV induced significant increases in renal cortical blood flow and urine sodium excretion, without altering MAP, GFR, and urine volume. Pretreatment infusion with a specific AT1 receptor antagonist, DuP 753, blocked or attenuated the subsequent AngII effects, while pretreatment infusion with the specific AT4 receptor antagonist, Divalinal-AngIV, blocked the AngIV effects. These results support distinct and opposite roles for AngII and AngIV, i.e. AngII acts as an anti-natriuretic agent, while AngIV acts as a natriuretic agent.

Requirement for STAT1 in LPS-induced gene expression in macrophages

This study examines the role of the signal transducer and activator of transcription 1 (STAT1) in induction of lipopolysaccharide (LPS)-stimulated gene expression both in vitro and in vivo. LPS-induced expression of an interferon (IFN)-inducible 10-kDa protein (IP-10), IFN regulatory factor-1 (IRF-1), and inducible nitric oxide synthase (iNOS) mRNAs was severely impaired in macrophages prepared from Stat1-/- mice, whereas levels of tumor necrosis factor alpha and KC (a C-X-C chemokine) mRNA in LPS-treated cell cultures were unaffected. A similar deficiency in LPS-induced gene expression was observed in livers and spleens from Stat1-/- mice. The reduced LPS-stimulated gene expression seen in Stat1-/- macrophages was not the result of reduced activation of nuclear factor kappaB. LPS stimulated the delayed activation of both IFN-stimulated response element and IFN-gamma-activated sequence binding activity in macrophages from wild-type mice. Activation of these STAT1-containing transcription factors was mediated by the intermediate induction of type I IFNs, since the LPS-induced IP-10, IRF-1, and iNOS mRNA expression was markedly reduced in macrophages from IFN-alpha/betaR-/- mice and blocked by cotreatment with antibodies against type I IFN. These results indicate that indirect activation of STAT1 by LPS-induced type I IFN participates in promoting optimal expression of LPS-inducible genes, and they suggest that STAT1 may play a critical role in innate immunity against gram-negative bacterial infection.

Expression of Mig (monokine induced by interferon-gamma) is important in T lymphocyte recruitment and host defense following viral infection of the central nervous system

Induction of a Th1 immune response against viral infection of the CNS is important in contributing to viral clearance. The present studies demonstrate a role for the T cell chemoattractant chemokine Mig (monokine induced by IFN-gamma) in contributing to a Th1 response against mouse hepatitis virus infection of the CNS. Analysis of the kinetics of Mig expression revealed mRNA transcripts present at days 7 and 12 postinfection (p.i.) but not early (day 2) or late (day 35) in the infection. To determine functional significance, mouse hepatitis virus-infected mice were treated with anti-Mig antisera, and the severity of disease was evaluated. Such treatment resulted in a marked increase in mortality that correlated with a >3 log increase in viral burden within the brains as compared with control mice treated with normal rabbit serum. Anti-Mig-treated mice displayed a significant decrease (p < 0.005) in CD4(+) and CD8(+) T cell recruitment into the CNS as compared with normal rabbit serum-treated mice. In addition, anti-Mig treatment resulted in a significant decrease (p < 0.05) in levels of IFN-gamma and IFN-beta that coincided with increased (p < 0.02) expression of the anti-inflammatory Th2 cytokine IL-10 within the CNS. Collectively, these data indicate that Mig is important in contributing to host defense by promoting a protective Th1 response against viral infection of the CNS.

Acute ocular effects of mustard gas: ultrastructural pathology and immunohistopathology of exposed rabbit cornea

Whole-body exposure to sulfur mustard (HD) produces cutaneous, respiratory and ocular impairment. Of these, ocular damage causes the most immediate incapacitation. Heretofore, characterization of HD ocular toxicity has been largely limited to gross and histological observations. In the present study we explore histological, ultrastructural and immunopathological acute effects of HD ocular exposure and establish correlations with HD toxicity data already documented for dermal exposure. Anesthetized rabbits were exposed to 0.4 microl of liquid HD placed directly on the cornea. Animals were euthanized at 6, 9 and 24 h post-exposure and the eyes were enucleated and processed for histopathology, ultrastructural and immunoperoxidase study. At 6 and 9 h, the most prominent histological feature was nuclear pyknosis, necrosis and loss of polarity of corneal epithelial basal cells to the exclusion of other epithelial cells. At 24 h, all corneal epithelial cells presented degenerative changes, with the epithelium eventually detaching from the underlying basement membrane at the level of the lamina lucida. Microblisters, a characteristic HD-induced skin pathology of the basement membrane zone of animals, were absent in this corneal study. Edema, degenerating fibroblasts and inflammatory cellular infiltrates were persistent stromal responses. Immunopathological effects included changes in antigenicity of bullous pemphigoid protein, laminin, desmosonal protein, Ki67 and p53. These morphological and immunopathological effects of corneal exposure to HD appear to be largely consistent with that previously reported for dermal exposures, perhaps providing shared anatomical considerations for the development of specific HD prophylaxis and therapy.

Interleukin-4/STAT6 represses STAT1 and NF-kappa B-dependent transcription through distinct mechanisms

STAT6 mediates interleukin-4 (IL-4)-dependent positive and negative regulation of inflammatory gene expression. In the present report we examined the molecular mechanisms involved in IL-4-induced repression of reporter gene transcription driven by STAT1 and/or NF-kappaB. Transient expression of STAT6 in a STAT6-deficient cell line (HEK 293) conferred sensitivity to IL-4 for STAT6-dependent transcription and for repression of interferon-gamma (IFNgamma)/STAT1- and/or tumor necrosis factor-alpha (TNFalpha)/NF-kappaB-driven reporter gene expression. In cells transfected with a deletion mutant of STAT6 lacking its transactivating domain, IL-4 could not mediate either positive or negative control of reporter gene expression. Overexpression of CREB-binding protein dramatically enhanced IL-4/STAT6-stimulated transcription and overcame IL-4-mediated repression of TNFalpha/NF-kappaB-dependent but not IFNgamma/STAT1-dependent transcription. A single amino acid change in the DNA-binding domain of STAT6 (H415A) selectively reduced the affinity of STAT6 for IL-4-responsive STAT sequence motifs (N4) without affecting the affinity for IFNgamma-responsive (GAS) sequences (N3) and, accordingly, eliminated transcription from an IL-4-responsive promoter. Interestingly, this mutation eliminated IL-4-mediated suppression of reporter gene transcription stimulated by TNFalpha/NF-kappaB but retained nearly full capacity to suppress IFNgamma/STAT1-stimulated transcription. Taken together these results demonstrate that STAT6 mediates suppression of STAT1 and NF-kappaB-dependent transcription by distinct mechanisms. Both processes are dependent upon the STAT6 transactivation domain and may involve sequestration of necessary but different transcriptional coactivator proteins. These two suppressive mechanisms are controlled differentially by the nature of the STAT6 DNA-binding site (i.e. N3 versus N4).

Smooth muscle cell surface tissue factor pathway activation by oxidized low-density lipoprotein requires cellular lipid peroxidation

Tissue factor, which is expressed in vascular lesions, increases thrombin production, blood coagulation, and smooth muscle cell proliferation. We demonstrate that oxidized low-density lipoprotein (LDL) induces surface tissue factor pathway activity (ie, activity of the tissue factor:factor VIIa complex) on human and rat smooth muscle cells. Tissue factor messenger RNA (mRNA) was induced by oxidized LDL or native LDL; however, native LDL did not markedly increase tissue factor activity. We hypothesized that oxidized LDL mediated the activation of the tissue factor pathway via an oxidant-dependent mechanism, because antioxidants blocked the enhanced tissue factor pathway activity by oxidized LDL, but not the increased mRNA or protein induction. We separated total lipid extracts of oxidized LDL using high-performance liquid chromatography (HPLC). This yielded 2 major peaks that induced tissue factor activity. Of the known oxysterols contained in the first peak, 7alpha- or 7beta-hydroxy or 7-ketocholesterol had no effect on tissue factor pathway activity; however, 7beta-hydroperoxycholesterol increased tissue factor pathway activity without induction of tissue factor mRNA. Tertiary butyl hydroperoxide also increased tissue factor pathway activity, suggesting that lipid hydroperoxides, some of which exist in atherosclerotic lesions, activate the tissue factor pathway. We speculate that thrombin production could be elevated via a mechanism involving peroxidation of cellular lipids, contributing to arterial thrombosis after plaque rupture. Our data suggest a mechanism by which antioxidants may offer a clinical benefit in acute coronary syndrome and restenosis.

The T cell chemoattractant IFN-inducible protein 10 is essential in host defense against viral-induced neurologic disease

The contribution of the T cell chemoattractant chemokine IFN-inducible protein 10 (IP-10) in host defense following viral infection of the CNS was examined. IP-10 is expressed by astrocytes during acute encephalomyelitis in mouse hepatitis virus-infected mice, and the majority of T lymphocytes infiltrating into the CNS expressed the IP-10 receptor CXCR3. Treatment of mice with anti-IP-10 antisera led to increased mortality and delayed viral clearance from the CNS as compared with control mice. Further, administration of anti-IP-10 led to a >70% reduction (p </= 0.001) in CD4+ and CD8+ T lymphocyte infiltration into the CNS, which correlated with decreased (p </= 0.01) levels of IFN-gamma. These data indicate that IP-10 functions as a sentinel molecule in host defense and is essential in the development of a protective Th1 response against viral infection of the CNS.

Intraallograft chemokine RNA and protein during rejection of MHC-matched/multiple minor histocompatibility-disparate skin grafts

Chemokines direct leukocyte recruitment into sites of tissue inflammation and may facilitate recruitment of leukocytes into allografts following transplantation. Although the expression of chemokines during rejection of MHC-disparate allografts has been examined, chemokine expression in MHC-matched/multiple minor histocompatibility Ag-disparate allografts has not been tested. The intraallograft RNA expression of several C-X-C and C-C chemokines was tested during rejection of full thickness skin grafts from B10. D2 donors on control Ig-, anti-CD4 mAb-, and anti-CD8 mAb-treated BALB/c recipients. In all recipients, two patterns of intragraft chemokine expression were observed during rejection of these grafts: 1) macrophage-inflammatory protein-1alpha, macrophage-inflammatory protein-1beta, GRO-alpha (KC), JE, and IFN-gamma-inducible protein (IP-10) were expressed at equivalent levels in allo- and isografts for 2-4 days posttransplant and then returned to low or undetectable levels; and 2) IP-10 and monokine induced by IFN-gamma (Mig) were expressed in the allografts 3 days before rejection was completed, suggesting a possible role in recruiting primed T cells into the allograft. Three days before completion of rejection, intraallograft IP-10 protein was restricted to the epidermis, whereas Mig was located in the lower dermis and associated with the intense infiltration of mononuclear cells. Treatment of B10.D2 recipients with rabbit antiserum to Mig, but not to IP-10, delayed rejection of the allografts 3-4 days. The results suggest that Mig mediates optimal recruitment of T cells into MHC-matched/multiple minor histocompatibility Ag-disparate allografts during rejection.

Regulation of macrophage gene expression by pro- and anti-inflammatory cytokines

The anti-inflammatory cytokines IL-4 and IL-10 are well recognized as important negative regulators of proinflammatory gene expression in mononuclear phagocytes. The intracellular mechanisms which mediate these responses appear to be multifactorial. IL-4 is able to markedly suppress transcriptional activation of IFNgamma-responsive genes and the promoter sequences required for both IFNgamma and IL-4 sensitivity are identical. IFNgamma-activated STAT1 and IL-4-activated STAT6 can both form complexes on the same regulatory sequence element; while STAT1 functions to promote transcription, STAT6 is inactive. STAT6 is, however, required for the suppressive activity of IL-4. In this model, IL-4 appears to suppress IFNgamma-inducible proinflammatory gene expression through the ability of STAT6 to compete with STAT1 for occupancy of promoter sites necessary for IFNgamma-induced transcriptional initiation. In a second model, IL-10 suppresses the expression of genes induced in LPS-stimulated macrophages through a pathway involving destabilization of specific mRNAs. We have demonstrated that nucleotide sequences in the 3'-untranslated region of an IL-10-sensitive gene can both destabilize a stable reporter mRNA (CAT) and confer sensitivity to IL-10-mediated destabilization. Deletion and site-specific mutagenesis have mapped this to an AU-rich sequence motif similar to that found in many cytokine and growth factor mRNAs. IL-10 is able to modulate the activity of proteins capable of binding to this sequence and one or more of these may regulate the rate of mRNA degradation. Thus mechanisms through which IL-10 and IL-4 act to dampen inflammatory responses are mechanistically distinct and involve diverse intracellular signaling pathways.

Interleukin-1-mediated stabilization of mouse KC mRNA depends on sequences in both 5'- and 3'-untranslated regions

mRNA transcribed from the mouse KC chemokine gene accumulated to significantly higher levels in multiple cell types after treatment with interleukin 1alpha (IL-1alpha) as compared with tumor necrosis factor-alpha (TNFalpha). Although TNFalpha and IL-1alpha both signaled the activation of nuclear factor kappaB and enhanced transcription of the KC gene with equal potency, only IL-1alpha treatment resulted in stabilization of KC mRNA. Nucleotide sequences that confer sensitivity for IL-1alpha-mediated mRNA stabilization were identified within the 5'- and 3'-untranslated regions (UTRs) of KC mRNA using transient transfection of chimeric plasmids containing specific portions of KC mRNA linked to the chloramphenicol acetyltransferase (CAT) gene. When plasmids containing either the 3'- or 5'-UTR of KC mRNA were used, the half-life of CAT mRNA was unaltered either in untreated or IL-1alpha-stimulated cells. In contrast, CAT mRNA transcribed from plasmids that contained both the 5'- and 3'-UTRs of the KC mRNA decayed more rapidly than control CAT mRNA, and this enhanced decay was prevented in cells treated with IL-1alpha. A cluster of four overlapping AUUUA motifs within the 3'-UTR was required, whereas the 5'-UTR region exhibited orientation dependence. These findings indicate that cooperative function of the two nucleotide sequences involves a distinct signaling pathway used by IL-1alpha but not TNFalpha.

A chemokine-to-cytokine-to-chemokine cascade critical in antiviral defense

Macrophage inflammatory protein 1alpha (MIP-1alpha) promotes natural killer (NK) cell inflammation in livers during murine cytomegalovirus (MCMV) infections, and NK cell-produced interferon gamma (IFN-gamma) contributes to defense against MCMV infections. A specific role for local NK cell IFN-gamma production, however, has not been established. The importance of MIP-1alpha and NK cell-produced IFN-gamma in shaping endogenous immune responses and defense in different compartments was examined. MIP-1alpha deficiency profoundly decreased resistance to MCMV and was associated with dramatically reduced NK cell accumulation and IFN-gamma production in liver. MIP-1alpha-independent IFN-gamma responses were observed in serum and spleen, and infection-induced elevations in blood NK cell populations occurred in absence of the factor, but peak liver expression of another chemokine, the monokine induced by IFN-gamma (Mig), depended upon presence of MIP-1alpha, NK cells, and IFN-gamma. The Mig response was also important for viral resistance. Thus, serum cytokine responses are insufficient; MIP-1alpha is critical for NK cell migration and IFN-gamma delivery to mediate protection; and Mig induction in tissues is a downstream protective response resulting from the process. These results define a critical chemokine-to-cytokine-to-chemokine cascade required for defense during a viral infection establishing itself in tissues.

Immune-inflammatory mechanisms in IFNgamma-mediated anti-tumor activity

IFNgamma is a functionally pleiotropic cytokine which shows considerable potency in promoting anti-tumor functions in vivo. Despite limited efficacy when delivered systemically either to experimental animals or patients, IFNgamma appears to play an important and perhaps critical role in directing the development of immune-mediated tumor destruction when expressed within the tumor bed. This has been demonstrated both by use of tumor cells transduced to express IFNgamma and by the use of IL-12 which is able, at least is murine models, to promote an IFNgamma-dependent, T cell mediated anti-tumor response. Recent studies indicate that the therapeutic efficacy of IFNgamma in tumor models depends critically upon the ability of the tumor cells themselves to respond to IFNgamma. Though IFNgamma is able to induce anti-viral activity and has direct anti-proliferative effects on some tumor cell lines, immunomodulatory function also appears to be an important component of its anti-tumor action. This is mediated through the action of several different classes of IFNgamma-inducible gene expression which control antigen processing and presentation, leukocyte trafficking, and indirect tumor cytotoxicity.

Groalpha-mediated recruitment of neutrophils is required for elicitation of contact hypersensitivity

The factors mediating recruitment of immune T cells to challenge sites during contact hypersensitivity (CHS) responses remain unclear. To investigate the role of chemokines during elicitation of CHS, the temporal expression of chemokine genes in hapten-challenged ears was tested. KC (the murine homologoue of Groalpha) was expressed 30 min following hapten challenge in naive and hapten-sensitized mice. A rabbit KC-specific antiserum inhibited elicitation of CHS when administered to sensitized mice prior to hapten challenge. Injecting either neutrophils or immune CD8(+) T cells into the ear tissue of immune animals before hapten challenge circumvented the KC antiserum-mediated inhibition of CHS. Neutrophil depletion also inhibited CHS and was circumvented by injecting either neutrophils or hapten-primed CD8(+) T cells into ears of sensitized mice followed by specific hapten challenge. These results indicate that KC-directed neutrophil infiltration of hapten challenge sites is required for elicitation of CHS and suggest that neutrophils mediate recruitment of the hapten-specific CD8(+) T cells that subsequently produce cytokines mediating the hypersensitivity response.

Interferon-gamma and CXC chemokine induction by interleukin 12 in renal cell carcinoma

Interleukin 12 (IL-12) is known to play an important role in the development of an antitumor response. Its activity has been shown to be dependent upon the intermediate production of IFN-gamma and the influx into the tumor of CD8 lymphocytes. In a murine model, tumor regression induced by IL-12 treatment correlated with IFN-gamma, IP-10, and Mig expression in the tumor bed and was abrogated by antibodies to both chemokines. Here we examined the effects of rHuIL-12 on IFN-gamma and CXC chemokine gene expression in patients with renal cell carcinoma (RCC) in an attempt to determine whether a similar series of molecular events leading to IL-12-mediated tumor regression in mice is also detectable in humans. As in the murine RENCA model, cultured RCC cells themselves could be induced by IFN-gamma to synthesize IP-10 and Mig mRNA. Explanted RCC produced IFN-gamma and IP-10 mRNA in response to IL-12 treatment, which was consistent with the finding that biopsied RCC tumors from IL-12-treated patients also variably expressed augmented levels of those molecules after therapy. Although Mig mRNA was present in the majority of biopsied tumors prior to treatment, both the Mig and IP-10 chemokines as well as IFN-gamma were induced in the peripheral blood mononuclear cells of IL-12-treated patients. Skin biopsies of IL-12-treated patients also all synthesized IP-10 mRNA. This study demonstrates that recombinant human IL-12 therapy of patients with RCC has the potential to induce the expression of gene products within the tumor bed that may contribute to the development of a successful antitumor response.

Regulation of macrophage chemokine expression by lipopolysaccharide in vitro and in vivo

The host response to Gram-negative LPS is characterized by an influx of inflammatory cells into host tissues, which is mediated, in part, by localized production of chemokines. The expression and function of chemokines in vivo appears to be highly selective, though the molecular mechanisms responsible are not well understood. All CXC (IFN-gamma-inducible protein (IP-10), macrophage inflammatory protein (MIP)-2, and KC) and CC (JE/monocyte chemoattractant protein (MCP)-1, MCP-5, MIP-1alpha, MIP-1beta, and RANTES) chemokine genes evaluated were sensitive to stimulation by LPS in vitro and in vivo. While IL-10 suppressed the expression of all LPS-induced chemokine genes evaluated in vitro, treatment with IFN-gamma selectively induced IP-10 and MCP-5 mRNAs, but inhibited LPS-induced MIP-2, KC, JE/MCP-1, MIP-1alpha, and MIP-1beta mRNA and/or protein. Like the response to IFN-gamma, LPS-mediated induction of IP-10 and MCP-5 was Stat1 dependent. Interestingly, only the IFN-gamma-mediated suppression of LPS-induced KC gene expression was IFN regulatory factor-2 dependent. Treatment of mice with LPS in vivo also induced high levels of chemokine mRNA in the liver and lung, with a concomitant increase in circulating protein. Hepatic expression of MIP-1alpha, MIP-1beta, RANTES, and MCP-5 mRNAs were dramatically reduced in Kupffer cell-depleted mice, while IP-10, KC, MIP-2, and MCP-1 were unaffected or enhanced. These findings indicate that selective regulation of chemokine expression in vivo may result from differential response of macrophages to pro- and antiinflammatory stimuli and to cell type-specific patterns of stimulus sensitivity. Moreover, the data suggest that individual chemokine genes are differentially regulated in response to LPS, suggesting unique roles during the sepsis cascade.

Cutting edge: clustered AU-rich elements are the target of IL-10-mediated mRNA destabilization in mouse macrophages

In the present study we show that IL-10-mediated inhibition of inflammatory gene expression can be mediated by an AU-rich element (ARE) cluster present in the 3' untranslated region (3'UTR) of sensitive genes. A series of chloramphenicol acetyl transferase (CAT) reporter gene constructs were prepared in which different fragments from the IL-10-sensitive KC mRNA 3'UTR were placed downstream of the coding region of the reporter gene CAT. CAT mRNA containing the KC 3'UTR was markedly destabilized as compared with the control CAT mRNA, and the decay rate was further increased in cells stimulated with IL-10. The KC 3'UTR contains an ARE cluster and three isolated ARE motifs. The ARE cluster spanning nucleotides 378-399 appeared to be both necessary and sufficient to mediate sensitivity to IL-10 because a 116-nucleotide fragment that contains the cluster conferred sensitivity, while mutation of the sequence between positions 378 and 399 eliminated sensitivity. The destabilizing effect of IL-10 was relatively selective, as the stability of chimeric CAT mRNAs was not modulated in cells treated with IFN-gamma or IL-4.

Interleukin-10 suppresses IP-10 gene transcription by inhibiting the production of class I interferon

Interleukin-10 (IL-10) selectively inhibited lipopolysaccharide (LPS)-induced chemoattractant cytokine gene expression: levels of IP-10 mRNA were markedly suppressed in IL-10-treated mouse peritoneal macrophages, whereas the expression of the RANTES mRNA was only modestly reduced. IL-10 inhibited IP-10 mRNA accumulation by reducing IP-10 gene transcription as demonstrated by nuclear run-on analysis. Interestingly, the ability of IL-10 to inhibit expression of IP-10 was dependent on the inducing stimulus; IL-10 did not suppress interferon gamma (IFNgamma)- or IFNbeta-stimulated IP-10 transcription or mRNA accumulation. These results suggested that IL-10 might act indirectly to suppress IP-10 expression by inhibiting LPS-induced class I IFN production. This hypothesis was supported by the following observations. First, LPS-induced IP-10 mRNA expression was blocked in cells cotreated with cycloheximide. Second, IL-10 inhibited the production of IFN/beta-mediated antiviral activity. Finally, the IL-10-mediated suppression of LPS-stimulated IP-10 production could be rescued by cotreatment with IFNbeta.

Oxidized LDL modulates activation of NFkappaB in mononuclear phagocytes by altering the degradation if IkappaBs

Oxidized low density lipoprotein (oxLDL) is known to alter the expression of inflammatory gene products in mononuclear phagocytes. The mechanisms involved in this effect were studied by examining the activation of nuclear factor kappaB (NFkappaB), a transcription factor known to be important in controlling the expression of such genes. Pretreatment of peritoneal macrophages with oxLDL modulated the activation of NFkappaB in response to either lipopolysaccharide (LPS) or the combination of interferon-gamma (IFN-gamma) and interleukin-2 (IL-2). In macrophages pretreated with oxLDL the nuclear translocation of Rel family members (RelA and c-Rel) is delayed (LPS) or markedly diminished (IFN-gamma/IL-2) and results in delayed or reduced appearance of kappaB binding activity within the nucleus. These changes in NFkappaB activation result from alterations in the stimulus-dependent degradation of IkappaB alpha and IkappaB beta. The effects of oxLDL on NFkappaB activation depend both on the degree of LDL oxidation (most potent with extensive oxidation) and on the time of exposure of the cells to the lipoprotein preparation (a minimal exposure of 6 h is required before inhibitory effects are observed). The modulation of IkappaB/NFkappaB function in cells exposed to oxLDL appears to be responsible for previously reported effects of oxLDL on chemoattractant cytokine gene expression where both inhibition and delay of such stimulus-dependent events has been observed.

STAT6 is required for the anti-inflammatory activity of interleukin-4 in mouse peritoneal macrophages

Interleukin-4 (IL-4) is an anti-inflammatory cytokine which inhibits many inducible macrophage functions. The present study demonstrates that the ability of IL-4 to inhibit interferon gamma (IFNgamma)-dependent gene transcription is dependent upon STAT6. IL-4 suppressed IFNgamma-induced expression of the MIG (monokine induced by IFNgamma) gene, a C-X-C chemokine, in mouse macrophages. IFNgamma-induced expression of MIG mRNA was abolished in peritoneal macrophages from Stat1-/- mice, and the suppression of MIG mRNA by IL-4 was abolished in macrophages from Stat6-/- mice. Transient transfection assays using a reporter gene containing the MIG gene promoter or the IFNgamma-responsive element (gammaRE) from the MIG gene revealed that the IFNgamma-dependent transcription was suppressed by IL-4, although IL-4 alone had no transactivating function. IFNgamma and IL-4 activated STAT1 and STAT6, respectively, and both proteins were able to bind the gammaRE motif. Furthermore, STAT6 was associated with the co-activator CREB-binding protein in RAW264.7 cells. These observations indicate that STAT6 is necessary for the IL-4-mediated suppression of IFNgamma-induced, STAT1-dependent transcription and suggest that STAT6 may directly suppress the STAT1-dependent transcription by competing with STAT1 for occupancy of the gammaRE motif and/or by competing with limiting quantities of the transcriptional coactivator.

The CXC chemokines IP-10 and Mig are necessary for IL-12-mediated regression of the mouse RENCA tumor

The role of the non-ELR-containing CXC chemokines IP-10 and Mig in antitumor activity induced by systemic treatment with IL-12 was examined in mice bearing the murine renal adenocarcinoma RENCA. IL-12 treatment produces a potent antitumor effect that is associated with tumor infiltration by CD8+ T lymphocytes. The regression of tumor is associated with the elevated expression of the IFN-gamma-inducible chemokines IP-10 and Mig within the tumor tissue. IP-10 and Mig have been shown to function as chemoattractants for activated T lymphocytes. In animals treated with rabbit polyclonal Abs specific for IP-10 and for Mig, the IL-12-induced regression of RENCA tumors was partially abrogated. This effect was associated with a dramatic inhibition of T cell infiltration. Thus, it appears that IL-12-dependent, T cell-mediated antitumor activity requires the intermediate expression of IP-10 and Mig to recruit antitumor effector T cells to the tumor site.

IL-10 suppresses LPS-induced KC mRNA expression via a translation-dependent decrease in mRNA stability

This study examines the mechanism of interleukin-10 (IL-10)-mediated suppression of KC chemokine gene expression in mouse macrophages. Suppression of KC mRNA levels by IL-10 occurred late in the time course of response to lipopolysaccharide (LPS). Equivalent IL-10-mediated suppression was observed when the agent was added 1 h before, simultaneous with, or 1 h after LPS. IL-10 did not inhibit KC gene transcription but rather produced a decrease in the stability of KC mRNA. The suppressive action of IL-10 was prevented in macrophages that were also treated with inhibitors of protein synthesis even when added 2 h after LPS and IL-10. These results suggest that IL-10 acts to destabilize LPS-induced KC mRNA through a process that depends on coincident KC mRNA translation.

Clinical and histologic trends of melanoma

BACKGROUND

Several changing clinical and histopathologic melanoma trends occurred from the 1950s to the 1980s.

OBJECTIVE

The purpose of this study was to evaluate melanoma trends during the past decade and to compare present trends to those documented during the past four decades.

METHODS

Sex, age at diagnosis, location, tumor thickness, stage, and histologic subtypes were evaluated from 1984 to 1995 and compared with trends during the past four decades.

RESULTS

Most changing trends from the past four decades have slowed or stabilized during the past decade.

CONCLUSION

Complete reporting of all melanomas to central tumor registries is necessary to accurately analyze present and future melanoma trends. Ongoing and new prevention and control strategies beginning at birth may be necessary to continue the positive efforts to curtail the melanoma epidemic.

Expression of human placental cell surface antigens on peripheral blood lymphocytes and lymphoblastoid cell lines

The expression of human placental cell surface antigens was examined in cells of lymphoid origin, including peripheral blood lymphocytes and cultured lymphoblastoid cells of bone marrow or thymus derivation. A select group of this defined set of surface antigens was detected on all three cell preparations. The most remarkable observation was the conspicuous absence of three subunits previously demonstrated to be present on all human cell surfaces examined to date. Antiserum directed against several placental components prevents adhesion and spreading of cells which grow attached to surfaces. These results suggest a role for these three glycoproteins in mediating cellular adhesion.

Cisplatin chemotherapy for treatment of thyroid carcinoma in dogs: 13 cases

The medical records of 13 dogs (10 spayed females, one intact male, one castrated male, and one dog of unknown gender) with histopathologically diagnosed thyroid carcinoma that were treated with cisplatin chemotherapy were reviewed. The mean age was 10.6 years. Three of the dogs were beagles. One dog had a c-cell medullary carcinoma, while the remaining 12 had follicular thyroid carcinoma. Eight of 13 dogs had tumors greater than 5 cm in diameter. In all 11 tumors for which information was available in the medical record, the masses were attached to underlying tissue. One dog underwent a complete remission, six had partial remissions, three had stable disease, and three had progressive disease. The mean time between initiation of cisplatin chemotherapy and development of progressive disease was 223.7 days (median, 202 days), with a mean survival time of 191.8 days (median, 98 days).

Autoradiographic identification of kidney angiotensin IV binding sites and angiotensin IV-induced renal cortical blood flow changes in rats

The present investigation initially determined that specific binding sites for the hexapeptide angiotensin IV (AngIV) are present in the rat kidney cortex and outer medulla but not in the inner medulla, using in vitro autoradiographic techniques. This binding site has been termed AT4, is distinct from the previously characterized AT1 and AT2 sites, and does not bind the specific AT1 receptor antagonist DuP753 or the AT2 receptor antagonist PD123177. Renal artery infusions of AngIV produced a dose-dependent increase in cortical blood flow without altering systemic blood pressure. In contrast, the infusion of angiotensin II (AngII) induced a dramatic decrease in cortical blood flow, accompanied by a significant elevation in systemic blood pressure. The infusion of [D-Val(1)]AngIV, an analog that does not bind at the AT4 receptor site, and the C-terminal truncated analogs AngIV (1-4) and AngIV (1-5) that possess lower affinity for this site, produced no change in cortical blood flow. The infusion of [Nle1]AngIV and [Lys1]AngIV, analogs that bind with high affinity at the AT4 receptor site, produced increases in cortical blood flow with no influence on blood pressure. Pretreatment with a specific AT4 receptor antagonist, Divalinal-AngIV, completely blocked AngIV-induced elevations in blood flow, but failed to influence AngII-induced decreases in blood flow, suggesting that these ligands are acting at different receptor sites. Pretreatment with the nitric oxide synthase inhibitor, NG-Monomethyl-L-Arginine, also blocked subsequent AngIV-induced increases in cortical blood flow. These data support the notion that AngIV exerts a unique influence upon renal hemodynamics via the AT4 receptor subtype, and suggest that AngIV-induced elevations in blood flow may be mediated by nitric oxide.

Calcipotriene-induced improvement in psoriasis is associated with reduced interleukin-8 and increased interleukin-10 levels within lesions

Calcipotriene is a synthetic analogue of 1,25-dihydroxyvitamin D3 established to be effective topically in the treatment of psoriasis. We investigated the early cellular and immunological events induced by calcipotriene in psoriasis. Thirty patients with moderate plaque-type psoriasis were randomly assigned to receive twice daily applications of either calcipotriene ointment 0.005% or matching vehicle for 6 weeks. Skin biopsies (6 mm) were performed from designated plaques at baseline and days 3 and 7. On these days and at weeks 2, 4 and 6, complete clinical evaluations were made in a double-blind fashion. Consistent with previous studies, significant clinical improvement (P < 0.05) in psoriasis was observed in patients receiving calcipotriene vs. those receiving vehicle by day 7 for scale and erythema, and by day 14 for thickness. No significant improvement, however, was seen on day 3. None of the immunohistological markers (CD1a, CD4, CD8, ICAM-1, VCAM-1, E-selectin, HLA-DR) semiquantitatively assessed in psoriatic plaques was significantly changed by calcipotriene treatment for 7 days. In the calcipotriene-treated group, interleukin (IL)-10 levels (pg/microgram of protein) increased by 57% from baseline (0.030 +/- 0.006; mean +/- SEM) to day 3 (0.047 +/- 0.011) (P = 0.05 vs. baseline; n = 10) and remained elevated at day 7 (0.046 +/- 0.012). IL-8 levels (pg/microgram of protein), however, declined by 70% from baseline (0.13 +/- 0.06) to day 3 (0.04 +/- 0.01), and remained low at day 7 (0.03 +/- 0.02) (P < 0.05 vs. baseline; n = 10). Both IL-8 and IL-10 were unaffected by vehicle treatment. Calcipotriene-induced clinical improvement of psoriasis is preceded by an increase in IL-10 and a concomitant decrease in IL-8 levels. The changes in the level of these two cytokines provide further evidence for immunological changes as a significant part of the mechanism of action of calcipotriene in psoriasis.

IL-4-induced STAT6 suppresses IFN-gamma-stimulated STAT1-dependent transcription in mouse macrophages

IL-4 suppresses the IFN-gamma-induced expression of the IFN regulatory factor-1 (IRF-1) gene, and this suppression is attenuated by increasing the amount of IFN-gamma. The effects of IFN-gamma and IL-4 on transcription of a reporter gene under control of a 1.3-kb fragment from the IRF-1 gene promoter or the STAT binding element (SBE) from this gene in the context of a heterologous promoter are similar to their effects on the endogenous IRF-1 gene. IFN-gamma-dependent transcription of reporter gene is suppressed by IL-4, but IL-4 alone has no trans-activating function. IL-4 treatment does not inhibit the tyrosine phosphorylation or nuclear translocation of IFN-gamma-activated STAT1. Rather, IFN-gamma and IL-4 independently activate STAT1 and STAT6, respectively, and both proteins bind to the IRF-1 SBE in homodimeric form. The affinity of STAT1 for the IRF-1 SBE is higher than the affinity of STAT6, as measured by competition with unlabeled oligonucleotide. These observations suggest that IL-4 may suppress IFN-gamma-stimulated transcription of the IRF-1 gene by activation of STAT6, which can compete with STAT1 for occupancy of the IRF-1 SBE when STAT1 levels are low. Suppression may be attenuated as the quantity of STAT1 relative to that of STAT6 increases in cells treated with increasing amounts of IFN-gamma and displaces STAT6.

IL-4-induced STAT6 suppresses IFN-gamma-stimulated STAT1-dependent transcription in mouse macrophages

IL-4 suppresses the IFN-gamma-induced expression of the IFN regulatory factor-1 (IRF-1) gene, and this suppression is attenuated by increasing the amount of IFN-gamma. The effects of IFN-gamma and IL-4 on transcription of a reporter gene under control of a 1.3-kb fragment from the IRF-1 gene promoter or the STAT binding element (SBE) from this gene in the context of a heterologous promoter are similar to their effects on the endogenous IRF-1 gene. IFN-gamma-dependent transcription of reporter gene is suppressed by IL-4, but IL-4 alone has no trans-activating function. IL-4 treatment does not inhibit the tyrosine phosphorylation or nuclear translocation of IFN-gamma-activated STAT1. Rather, IFN-gamma and IL-4 independently activate STAT1 and STAT6, respectively, and both proteins bind to the IRF-1 SBE in homodimeric form. The affinity of STAT1 for the IRF-1 SBE is higher than the affinity of STAT6, as measured by competition with unlabeled oligonucleotide. These observations suggest that IL-4 may suppress IFN-gamma-stimulated transcription of the IRF-1 gene by activation of STAT6, which can compete with STAT1 for occupancy of the IRF-1 SBE when STAT1 levels are low. Suppression may be attenuated as the quantity of STAT1 relative to that of STAT6 increases in cells treated with increasing amounts of IFN-gamma and displaces STAT6.

Mohs micrographic surgery for the treatment of dermatofibrosarcoma protuberans. Results of a multiinstitutional series with an analysis of the extent of microscopic spread

BACKGROUND

Dermatofibrosarcoma protuberans (DFSP) is an uncommon soft-tissue tumor of the skin; its microscopic extent of invasion beyond the grossly visible tumor is frequently difficult to appreciate. Although wide local excision has been the standard treatment of DFSP, recurrence rates range from 11% to 53%. Because Mohs micrographic surgery allows the extent of excision to be tailored to the microscopic extent of tumor, we evaluated this technique for the treatment of primary and recurrent DFSP.

OBJECTIVE

Our purpose was to determine the local recurrence rate and microscopic extent of spread of primary and recurrent DFSP after treatment with Mohs micrographic surgery.

METHODS

The records of 58 patients with primary and recurrent DFSP treated with Mohs micrographic surgery at three institutions were reviewed and the macroscopic and microscopic extents of tumor were recorded.

RESULTS

One patient with a twice-recurrent DFSP had another recurrence after Mohs micrographic surgery, for an overall local recurrence rate of 2% (zero for primary tumors and 4.8% for recurrent tumors). There were no cases of regional or distant metastases. Macroscopic tumor size ranged from 0.3 x 0.6 cm to 30 x 20 cm, whereas microscopic (postoperative) size ranged from 1.8 x 1.0 cm to 35 x 40 cm. We calculated the likelihood that a given width of excision around the macroscopic tumor would clear the entire microscopic extent of tumor. Standard wide excision with a width of 1 cm around the primary tumor would have left microscopic residual tumor in 70.7%; a width of 2 cm, 39.7%; 3 cm, 15.5%; and 5 cm, 5.2%. Even an excision width of 10 cm would not have cleared the microscopic extent of some tumors, despite taking a huge excess of normal tissue.

CONCLUSION

Treatment of primary and recurrent DFSP by Mohs micrographic surgery results in a low recurrence rate because of the ability of the technique to permit the detection and excision of microscopic tumor elements in even the most asymmetric tumors. Whatever type of surgery is chosen to treat DFSP, it is necessary to assess the entire perimeter of the tumor for microscopic extension and to achieve tumor-free margins in all directions.

Immunohistochemical studies of basement membrane proteins and proliferation and apoptosis markers in sulfur mustard induced cutaneous lesions in weanling pigs

Sulfur mustard (2,2-dichlorodiethyl sulfide, HD) is a chemical warfare agent that is a threat to both troops and civilians. The focus of HD research has been on intracellular adduct formation leading to apoptosis and/or necrosis in cutaneous lesions. However, there is work which suggests that HD may have a more direct effect on the basement membrane zone. Immunohistochemical staining to desmosomal proteins, cellular fibronectin, laminin 1, laminin 5, collagen IV, collagen VII, p53, Bcl-2, and PCNA was performed on weanling pig skin exposed to vesicating doses of HD, GB3, an antibody to laminin 5, showed a progressive decrease with loss of expression during the time period of clinical vesiculation. The other basement membrane proteins showed no change or inconsistent changes. PCNA, and p53 staining increased in the overlying epidermis in areas of vesiculation without significant necrosis. Bcl-2 positive cells were decreased or absent after exposure. This study implicates laminin 5 as the main basement membrane protein affected acutely by HD exposure. The patterns of staining of PCNA, Bcl-2, and p53 within the epidermis suggest that apoptosis and cellular necrosis both may play a role in cell death secondary to HD.

Depth of morphologic skin damage and viability after one, two, and three passes of a high-energy, short-pulse CO2 laser (Tru-Pulse) in pig skin

BACKGROUND

CO2 laser energy is absorbed by water, which is present in all tissue. The depth of penetration of CO2 lasers is narrow with minimal reflection, scatter, or transmission. However, thermal damage has limited the usefulness of conventional, continuous-wave CO2 lasers for debridement as demonstrated by wound healing studies. The development of high-energy CO2 lasers, with pulse durations that are less than the thermal relaxation time of tissue, have made vaporization of skin for resurfacing and wound debridement possible because of the decreased risk of thermal damage.

OBJECTIVE

This study was performed to evaluate thermal damage produced by a CO2 laser.

METHODS

Routine histopathologic examination and nitroblue-tetrazolium chloride (NBTC) staining were used to evaluate the depth of tissue damage and viability in weanling pig skin after one, two, and three passes of the laser.

RESULTS

At a pulse energy of 300 mJ, with a pulse duration of 60 microseconds, one pass of the laser produced vaporization of the epidermis with minimal thermal damage. Two passes produced areas of denatured collagen with loss of viable cells in the superficial papillary dermis. Three passes extended the damage into the papillary dermis.

CONCLUSION

Hyalinization of collagen appears to correspond well with the level of thermal damage as measured by NBTC staining. Our findings suggest that the energy necessary to vaporize the dermis may be greater than that needed to vaporize epidermis.

Excretory/secretory products from plerocercoids of Spirometra erinacei reduce iNOS and chemokine mRNA levels in peritoneal macrophages stimulated with cytokines and/or LPS

During infection with plerocercoids of Spirometra erinacei, organisms in the peritoneal cavity of infected animals have many bound inflammatory leukocytes yet survive apparently unharmed. Coculture of IFN gamma and LPS stimulated mouse peritoneal macrophages with live plerocercoids suppressed the mRNA expression of the inducible isoform of nitric oxide synthase (iNOS) and JE, the murine homologue of monocyte chemotactic protein-1 (MCP-1). Excretory/secretory (ES) products from plerocercoids also suppressed the induced iNOS and JE mRNA and reduced nitrite production of macrophages in a dose dependent manner. The suppression of inducible mRNA levels in macrophages cultured for 24 h with ES products varied with the nature of the stimuli; IFN gamma/ LPS-induced iNOS mRNA levels were effected less than were iNOS mRNA levels induced by IFN gamma/IL-2 or IFN gamma/ TNF alpha. Similar findings were obtained when nitrite production was measured. Thus modulation of LPS and cytokine inducible mRNA levels appear to be the primary target of ES products. We speculate that a major physiological role for this inhibitory activity in ES products might be the down regulation of pro-inflammatory gene expression.

A tandem GC box motif is necessary for lipopolysaccharide-induced transcription of the type II TNF receptor gene

LPS induces the expression of the gene encoding the type II TNF-alpha receptor in mononuclear phagocytes. To elucidate the nuclear signaling mechanisms involved in this response, a 772-bp fragment of the TNFRII gene promoter was analyzed by deletion and site-specific mutagenesis following transient transfection in the macrophage-like cell line RAW264.7. A region located between -100 and -75 relative to the transcription start site was found to be essential for LPS sensitivity. This contained a GC-rich region composed of two tandemly arrayed Sp-1 sites. While mutation of this region confirmed that it was essential for LPS sensitivity, the sequence was not able to confer LPS sensitivity upon a heterologous promoter. Internal deletion and site-specific mutagenesis of the 100-bp fragment identified regions immediately flanking an initiator region (Inr) site that were also necessary for sensitivity to LPS. Electrophoretic mobility shift assays demonstrated that the GC box bound Sp-1 and Sp-3, although the level of binding activity did not vary with LPS stimulation. An oligonucleotide probe containing nucleotide positions -45 to -18 also bound several protein complexes, but these were not enhanced by LPS. These findings indicate that the tandem GC box is necessary, but not sufficient, for LPS-mediated transcription of the TNFRII gene. A second apparently novel motif, located within 15 nucleotides of the Inr, is also necessary.

A tandem GC box motif is necessary for lipopolysaccharide-induced transcription of the type II TNF receptor gene

LPS induces the expression of the gene encoding the type II TNF-alpha receptor in mononuclear phagocytes. To elucidate the nuclear signaling mechanisms involved in this response, a 772-bp fragment of the TNFRII gene promoter was analyzed by deletion and site-specific mutagenesis following transient transfection in the macrophage-like cell line RAW264.7. A region located between -100 and -75 relative to the transcription start site was found to be essential for LPS sensitivity. This contained a GC-rich region composed of two tandemly arrayed Sp-1 sites. While mutation of this region confirmed that it was essential for LPS sensitivity, the sequence was not able to confer LPS sensitivity upon a heterologous promoter. Internal deletion and site-specific mutagenesis of the 100-bp fragment identified regions immediately flanking an initiator region (Inr) site that were also necessary for sensitivity to LPS. Electrophoretic mobility shift assays demonstrated that the GC box bound Sp-1 and Sp-3, although the level of binding activity did not vary with LPS stimulation. An oligonucleotide probe containing nucleotide positions -45 to -18 also bound several protein complexes, but these were not enhanced by LPS. These findings indicate that the tandem GC box is necessary, but not sufficient, for LPS-mediated transcription of the TNFRII gene. A second apparently novel motif, located within 15 nucleotides of the Inr, is also necessary.

Synergy between interferon-gamma and tumor necrosis factor-alpha in transcriptional activation is mediated by cooperation between signal transducer and activator of transcription 1 and nuclear factor kappaB

Interferon-gamma (IFNgamma) and tumor necrosis factor-alpha (TNFalpha) cooperate to induce the expression of many gene products during inflammation. The present report demonstrates that a portion of this cooperativity is mediated by synergism between two distinct transcription factors: signal transducer and activator of transcription 1 (STAT1) and nuclear factor kappaB (NF-kappaB). IFNgamma and TNFalpha synergistically induce expression of mRNAs encoding interferon regulatory factor-1 (IRF-1), intercellular adhesion molecule-1, Mig (monokine induced by gamma-interferon), and RANTES (regulated on activation normal T cell expressed and secreted) in normal but not STAT1-deficient mouse fibroblasts, indicating a requirement for STAT1. Transient transfection assays in fibroblasts using site-directed mutants of a 1.3-kilobase pair sequence of the IRF-1 gene promoter revealed that the synergy was dependent upon two sequence elements; a STAT binding element and a kappaB motif. Artificial constructs containing a single copy of both a STAT binding element and a kappaB motif linked to the herpes virus thymidine kinase promoter were able to mediate synergistic response to IFNgamma and TNFalpha; such response varied with both the relative spacing and the specific sequence of the regions between these two sites. Cooperatively responsive sequence constructs bound both STAT1alpha and NF-kappaB in nuclear extracts prepared from IFNgamma- and/or TNFalpha-stimulated fibroblasts, although binding of individual factors was not cooperative. Thus, the frequently observed synergy between IFNgamma and TNFalpha in promoting inflammatory response depends in part upon cooperation between STAT1alpha and NF-kappaB, which is most likely mediated by their independent interaction with one or more components of the basal transcription complex.

IL-4-induced expression of the IL-1 receptor antagonist gene is mediated by STAT6

IL-4 alone or in cooperation with LPS can induce the expression of the gene encoding the secreted-type IL-1 receptor antagonist (sIL-1ra) in mononuclear phagocytes. To determine the nuclear signaling mechanisms involved in this response, the region flanking the transcription start site of the human sIL-1ra gene was placed upstream of the luciferase reporter gene, and the function of specific sequence elements was analyzed following transient transfection in the macrophage-like cell line RAW264.7. A region located between -250 and -200 bases relative to the transcription start site was necessary for response to IL-4 alone and for cooperation between IL-4 and LPS. This 50-bp region contains two inverted repeat elements that represent potential binding sites for members of the signal transducer and activator of transcription (STAT) gene family (STAT-binding elements (SBEs)). Site-directed mutagenesis of the distal SBE abolished IL-4 responsiveness, and multiple copies of this motif were able to confer IL-4 sensitivity to luciferase expression in the context of a heterologous (herpes virus thymidine kinase) promoter. Mutation of the proximal SBE in the intact IL-1ra promoter had little or no effect on response to IL-4, and this sequence motif was inactive when examined alone. Electrophoretic mobility shift assays using an oligonucleotide corresponding to the distal SBE identified a single binding activity that was detected in nuclei within 15 min of IL-4 treatment and that was recognized by Ab to STAT6. These results indicate that IL-4-induced STAT6 is required for IL-4-induced transcriptional activation of the sIL-1ra gene.

IL-4-induced expression of the IL-1 receptor antagonist gene is mediated by STAT6

IL-4 alone or in cooperation with LPS can induce the expression of the gene encoding the secreted-type IL-1 receptor antagonist (sIL-1ra) in mononuclear phagocytes. To determine the nuclear signaling mechanisms involved in this response, the region flanking the transcription start site of the human sIL-1ra gene was placed upstream of the luciferase reporter gene, and the function of specific sequence elements was analyzed following transient transfection in the macrophage-like cell line RAW264.7. A region located between -250 and -200 bases relative to the transcription start site was necessary for response to IL-4 alone and for cooperation between IL-4 and LPS. This 50-bp region contains two inverted repeat elements that represent potential binding sites for members of the signal transducer and activator of transcription (STAT) gene family (STAT-binding elements (SBEs)). Site-directed mutagenesis of the distal SBE abolished IL-4 responsiveness, and multiple copies of this motif were able to confer IL-4 sensitivity to luciferase expression in the context of a heterologous (herpes virus thymidine kinase) promoter. Mutation of the proximal SBE in the intact IL-1ra promoter had little or no effect on response to IL-4, and this sequence motif was inactive when examined alone. Electrophoretic mobility shift assays using an oligonucleotide corresponding to the distal SBE identified a single binding activity that was detected in nuclei within 15 min of IL-4 treatment and that was recognized by Ab to STAT6. These results indicate that IL-4-induced STAT6 is required for IL-4-induced transcriptional activation of the sIL-1ra gene.

Concurrent application of tretinoin (retinoic acid) partially protects against corticosteroid-induced epidermal atrophy

Cutaneous atrophy arising from prolonged use of potent topical corticosteroids has long been a concern. Thus, it would be advantageous to find an agent which protects against atrophy produced by corticosteroids but at the same time does not impair their anti-inflammatory effects. Recent work shows that topical all-trans retinoic acid (tretinoin) prevents skin atrophy in mice treated with topical corticosteroids, but such studies have not been performed in humans. We performed an 8-week clinical, histological and biochemical study to test the ability of tretinoin to enhance efficacy and inhibit atrophogenicity of topical corticosteroids, when used in the treatment of psoriasis. In each of 20 psoriasis patients, one plaque, and its perilesional skin, was treated once daily with betamethasone dipropionate and tretinoin 0.1%, and one plaque, and its perilesional skin, treated with once daily betamethasone dipropionate and tretinoin vehicle. There was no difference in the speed or degree of improvement in plaques treated with either the topical corticosteroid/tretinoin combination or with corticosteroid alone. Light microscopy revealed a 19% reduction in epidermal thickness, in corticosteroid-treated perilesional skin, as compared with a slight (1%) increase in corticosteroid/tretinoin-treated perilesional areas (P = 0.067). Western blot analysis showed a 55% reduction in procollagen I aminopropeptide in perilesional skin treated corticosteroid alone, as compared with a 45% reduction in corticosteroid/tretinoin-treated perilesional skin. These data indicate that the addition of tretinoin does not impair the efficacy of a topical corticosteroid, in the treatment of psoriasis, and partially ameliorates epidermal atrophy produced by the topical corticosteroid.

Oxidized LDL potentiates LPS-induced transcription of the chemokine KC gene

Oxidized low-density lipoprotein (LDL) has been shown to modulate the expression of multiple gene products associated with inflammation in several different cell types including mononuclear phagocytes. The reported effects vary dramatically, however, depending upon cell type, stimulus, and degree of LDL oxidation. In the present report, oxidized LDL has been found to markedly potentiate expression of the KC chemokine gene in lipopolysaccharide (LPS)-stimulated macrophages. Pretreatment of elicited mouse peritoneal macrophages with oxidized LDL but not native LDL produced a significant enhancement of LPS-induced KC mRNA expression, whereas levels of IP-10 mRNA, another CXC chemokine, were altered in opposite fashion. The alteration in KC mRNA expression was dependent upon the dose, exposure time, and extent of LDL oxidation. Oxidized LDL selectively prolonged the expression of KC mRNA. Surprisingly this was not a consequence of altered mRNA stability, but rather of prolonged transcription. These effects on KC gene transcription were in marked contrast to previous reports demonstrating inhibitory effects of oxidized LDL on LPS-induced macrophage chemokine expression. Thus extensively oxidized LDL acts on the transcriptional control process in macrophages in both positive and negative fashion on separate members of the same gene family.

LPS does not directly induce STAT activity in mouse macrophages

Induction of gene expression in cytokine-treated cells involves the protein tyrosine kinase-dependent activation of members of the STAT family of transcription factors. To determine if lipopolysaccharide (LPS) might activate one or more STAT factors, nuclear extracts from LPS-treated RAW264.7 macrophages were assayed for STAT-like DNA binding activity using oligonucleotides recognized by different members of this protein family. Within 30 min a single LPS-inducible DNA-protein complex was detected using three separate oligonucleotides. This activity was not reactive with anti-STAT antibodies and was subsequently identified as composed of the NF kappa B components NF kappa B1 and Rel-A. Thus, LPS does not directly stimulate STAT factors with known sequence-specific DNA binding activity.