Loss of Interleukin-6 Influences Transcriptional Immune Signatures and Alters Bacterial Colonization in the Skin

The skin functions as a protective barrier to inhibit the entry of foreign pathogens, all the while hosting a diverse milieu of microorganisms. Over time, skin cells, immune cells, cytokines, and microbes interact to integrate the processes of maintaining the skin's physical and immune barrier. In the present study, the basal expression of two immunologically divergent mouse strains C57BL/6 and BALB/c, as well as a strain on the C57 background lacking IL-6, was characterized. Additionally, cutaneous antimicrobial gene expression profiles and skin bacterial microbiome were assessed between strains. Total RNA sequencing was performed on untreated C57BL/6 (control), BALB/c, and IL-6-deficient skin samples and found over 3,400 genes differentially modulated between strains. It was found that each strain modulated its own transcriptional "profile" associated with skin homeostasis and also influenced the overall bacterial colonization as indicated by the differential phyla present on each strain. Together, these data not only provide a comprehensive view of the transcriptional changes in homeostatic skin of different mouse strains but also highlight the possible influence of the strain differences (e.g., Th1/Th2 balance) as well as a role for IL-6 in overall skin immunity and resident microbial populations.

TNF-Alpha as an Initiator of Allodynia and Anxiety-Like Behaviors in a Preclinical Model of PTSD and Comorbid Pain

Post-Traumatic Stress Disorder (PTSD) is a debilitating mental health disorder that occurs after exposure to a traumatic event. Patients with comorbid chronic pain experience affective distress, worse quality of life, and poorer responses to treatments for pain or PTSD than those with either condition alone. FDA-approved PTSD treatments are often ineffective analgesics, requiring additional drugs to treat co-morbid symptoms. Therefore, development of new treatment strategies necessitate a better understanding of the pathophysiology of PTSD and comorbid pain. The single prolonged stress (SPS) model of PTSD induces the development of persistent mechanical allodynia and thermal hyperalgesia. Increased Nociceptin/Orphanin FQ (N/OFQ) levels in serum and CSF accompany these exaggerated nociceptive responses, as well as increased serum levels of the pro-inflammatory cytokine tumor necrosis factor (TNF-α). Therefore, the primary goal was to determine the role of TNF-α in the development of SPS-induced allodynia/hyperalgesia and elevated serum and CNS N/OFQ using two approaches: TNF-α synthesis inhibition, and blockade with anti-TNF-α antibody that acts primarily in the periphery. Administration of TNF-α synthesis blocker, thalidomide (THL), immediately after SPS prevented increased TNF-α and development of allodynia and hyperalgesia. The THL effect lasted at least 21 days, well after thalidomide treatment ended (day 5). THL also prevented SPS-induced increases in serum N/OFQ and reversed regional N/OFQ mRNA expression changes in the CNS. Serum TNF-α increases detected at 4 and 24 h post SPS were not accompanied by blood brain barrier disruption. A single injection of anti-TNF-α antibody to male and female rats during the SPS procedure prevented the development of allodynia, hyperalgesia, and elevated serum N/OFQ, and reduced SPS-induced anxiety-like behaviors in males. Anti-TNFα treatment also blocked development of SPS-induced allodynia in females, and blocked increased hypothalamic N/OFQ in males and females. This suggests that a peripheral TNF-α surge is necessary for the initiation of allodynia associated with SPS, as well as the altered central and peripheral N/OFQ that maintains nociceptive sensitivity. Therefore, early alleviation of TNF-α provides new therapeutic options for investigation as future PTSD and co-morbid pain treatments.

Evaluation of skin irritation following weathered crude oil exposure in two mouse strains

Petroleum crude oil spills are common and vary in size and scope. Spill response workers throughout the course of remediation are exposed to so-called weathered oil and are known to report diverse health effects, including contact dermatitis. A murine model of repeated exposure to weathered marine crude oil was employed utilizing two strains of mice, C57BL/6 and BALB/c, to investigate the pathology of this irritant and identify the principal hydrocarbon components deposited in skin. Histopathology demonstrated clear signs of irritation in oil-exposed skin from both mouse strains, characterized by prominent epidermal hyperplasia (acanthosis). BALB/c mice exposed to oil demonstrated more pronounced irritation compared with C57BL/6 mice, which was characterized by increased acanthosis as well as increased inflammatory cytokine/chemokine protein expression of IL-1β, IL-6, CXCL10, CCL2, CCL3, CCL4, and CCL11. A gas chromatography/mass spectrometry method was developed for the identification and quantification of 42 aliphatic and EPA priority aromatic hydrocarbons from full thickness skin samples of C57BL/6 and BALB/c mice exposed to oil samples. Aromatic hydrocarbons were not detected in skin; however, aliphatic hydrocarbons in skin tended to accumulate with carbon numbers greater than C16. These preliminary data and observations suggest that weathered crude oil is a skin irritant and this may be related to specific hydrocarbon components, although immune phenotype appears to impact skin response as well.

IL6Rα function in myeloid cells modulates the inflammatory response during irritant contact dermatitis

Irritant contact dermatitis (ICD) is characterized by epidermal hyperplasia, infiltration of leucocytes into lesional skin and inflammatory cytokine release. The cellular infiltrate during ICD comprises primarily cells of the myeloid lineage. Our group has previously shown that the cytokine IL-6 confers a protective effect to lesional skin during ICD. How IL-6Rα function in myeloid cells is involved in the inflammatory response during ICD is, however, unknown. In the present study, utilizing a chemical model of ICD, it is shown that mice with a myeloid-specific knockout of the IL-6Rα (IL-6Rα^Δmyeloid ) display an exaggerated inflammatory response to benzalkonium chloride (BKC) and Jet propellant-8 (JP8) fuel, two well-characterized irritants relative to littermate control. Results from immunohistochemical and flow cytometric analyses revealed that IL-6Rα^Δmyeloid mouse skin displayed increased epidermal hyperplasia and inflammatory monocyte influx into lesional skin but lower numbers of resident macrophages relative to littermate controls after irritant exposure. Multiplex immunoassay revealed significantly higher levels of pro-inflammatory cytokines IL-1α and TNF-α, but reduced expression of chemokine proteins including CCL2-5, CCL7, CCL11, CXCL1 and CXCL10 in IL-6Rα^Δmyeloid mouse skin relative to littermate control following irritant exposure. These results highlight a previously unknown role of IL-6Rα function in myeloid cells in modulating the inflammatory response and myeloid population dynamics during ICD.

Keratinocyte-specific deletion of the IL-6RΑ exacerbates the inflammatory response during irritant contact dermatitis

Irritant Contact Dermatitis (ICD) is the most common occupational skin disorder. During ICD, keratinocytes initiate the inflammatory cascade by producing cytokines including IL-6. This laboratory previously reported that IL-6 deficiency exacerbates skin inflammation during ICD, yet the role of the IL-6Rα in keratinocyte function has yet to be elucidated. To investigate how IL-6Rα function in keratinocytes influences the inflammatory response during ICD, keratinocyte-specific IL-6Rα KO (IL6ra^Δker) and WT mice were exposed to two well-known occupational irritants; JP-8 jet fuel, and benzalkonium chloride (BKC), or acetone control for three days. Dermatitis lesions were collected and flow cytometric and immunohistochemical analyses revealed that IL6ra^Δker skin displayed increased populations of CD11b⁺CD45⁺ and F4/80⁺ cells respectively relative to WT. However, IL6ra^Δker mouse skin contained reduced numbers of γδ T cells relative to WT. Furthermore, IL6ra^Δker skin expressed increased levels of pro-inflammatory cytokines including IL-1β, IL-22, and CCL4 but decreased levels of anti-inflammatory cytokines IL-4 and IL-10. These results indicate that epidermal keratinocyte IL-6Rα function modulates epidermal hyperplasia, immune cell infiltration into skin and cytokine expression during ICD and suggests that the previously reported protective effect of IL-6 during ICD might be mediated primarily by keratinocyte derived IL-6Rα.

Geochemical characterization and renal cell toxicity of water-soluble extracts from U.S. Gulf Coast lignite

An assortment of organic material can leach from lignite (low-rank coal) in water, and the water-soluble fraction from lignite has been associated with adverse health effects in areas of the Balkans. Recent efforts have been made to evaluate this hypothesis in other areas where lignite is in contact with groundwater like in the U.S. Gulf Coast region. In this study, five Gulf Coast lignite samples were extracted with water, and the water-soluble portion of the coal was then characterized by total organic carbon, UV-Vis spectroscopy, and gas chromatography/mass spectrometry. Additionally, human kidney cells (HK-2) were exposed to water-soluble extracts of Gulf Coast lignite to assess toxicity. Cell viability was measured, and a dose-response curve was used to generate IC₅₀ values that ranged from 490 to 3000 ppm. The most toxic extract (Dolet Hills) was from Louisiana where lignite-derived organic material has been previously linked to high incidence of renal pelvic cancer. Concentrations of nephrotoxic metals (As, Cd, Co, Cu, Hg, Pb, V, Zn) were screened and were below those considered toxic to renal cells. We conclude that leachates from lignite do indeed have toxic affects on cultured human renal cells. Although the IC₅₀ values are higher than the concentration of organic matter in the local groundwater, typically < 5 ppm, the effects of long-term low-level exposure is not known.

Interleukin (IL)-6 modulates transforming growth factor-β receptor I and II (TGF-βRI and II) function in epidermal keratinocytes

It been shown that IL-6 modulates TGF-β1 expression in fibroblasts, however, what role IL-6 plays concerning TGF-βR expression and function in skin is unknown. Therefore, the aim of this study was to investigate the mechanism by which IL-6 might modulates TGF-β receptors in skin. Skin from WT, IL-6 over-expressing mice and IL-6 treated keratinocyte cultures was analysed for TGF-βRI and TGF-βRII expression via histology, PCR and flow cytometry. Receptor function was assessed by cell migration, bromodeoxyuridine (BrdU) proliferation assays, and Smad7 expression and Smad2/3 phosphorylation. Receptor localization within the membrane was determined by co-immunoprecipitation. IL-6 overexpression and treatment increased TGF-βRII expression in the epidermis. IL-6 treatment of keratinocytes induced TGF-βRI and II expression and augmented TGF-β1-induced function as demonstrated through increased migration and decreased proliferation. Additionally, IL-6 treatment of keratinocytes altered receptor activity as indicated by altered Smad2/3 phosphorylation and increased Smad7 and membrane localization. These results suggest that IL-6 regulates keratinocyte function by modulating TGF-βRI and II expression and signal transduction via trafficking of the receptor to lipid raft pools.

IL-6 influences the balance between M1 and M2 macrophages in a mouse model of irritant contact dermatitis

Irritant contact dermatitis (ICD) is an acute inflammatory response that is ranked the 2nd most prevalent occupational injury associated with workman’s compensation. Interleukin-6 (IL-6), a pro-inflammatory cytokine produced in the skin, is closely associated with healing and decreased levels are associated with more severe ICD. The phenotypic nature of the macrophage infiltrate during skin inflammation can greatly influence damage and healing during ICD. The pro-inflammatory, classically activated (M1) macrophage produce cytokines such as IL-6, IL-1, and TNFα, while alternatively activated (M2) macrophages produce IL-10 and TGFβ, and are thought to be associated with tissue repair. IL-6 may play a regulatory role in mediating the M1 versus M2 phenotypic change in skin. To examine the role of IL-6 in ICD, IL-6KO and C57 mice were exposed to benzoalkonium chloride (BKC) for 7 days. IL-6KO mice displayed decreased expression of CD206 (M2) as compared to CD86 (M1) and the ration of CD86:CD206 was significantly increased in IL-6KO mice compared to control. Multiplex protein analysis showed expression of multiple M1-related cytokines such IFN-g, CCL3, CCL4, CCL5, and CCL7 significantly modulated in IL6-KO BKC treated mice compared to C57. Additionally, M2 related cytokine/chemokine receptors IL-4R and CCR1 were significantly dysregulated in IL-6KO BKC treated mice. IL-6 treatment of RAW cells enhanced the expression of CD206 in manner similar to IL-4. Overall, these results further confirm a role for IL-6 in macrophage polarization and could eventually result in the development of therapies for dermatitis based on this cytokines activity.

IL-6 deficiency exacerbates skin inflammation in a murine model of irritant dermatitis

Contact dermatitis is the second most reported occupational injury associated with workers compensation. Inflammatory cytokines are closely involved with the development of dermatitis, and their modulation could exacerbate skin damage, thus contributing to increased irritancy. IL-6 is a pro-inflammatory cytokine paradoxically associated with both skin healing and inflammation. To determine what role this pleiotropic cytokine plays in chemically-induced irritant dermatitis, IL-6 deficient (KO), IL-6 over-expressing transgenic (TgIL6), and corresponding wild-type (WT) mice were exposed to acetone or the irritants JP-8 jet fuel or benzalkonium chloride (BKC) daily for 7 days. Histological analysis of exposed skin was performed, as was tissue mRNA and protein expression patterns of inflammatory cytokines via QPCR and multiplex ELISA. The results indicated that, following JP-8 exposure, IL-6KO mice had greatly increased skin IL-1β, TNFα, CCL2, CCL3, and CXCL1 mRNA and corresponding product protein expression when compared to that of samples from WT counterparts and acetone-exposed control mice. BKC treatment induced the expression of all cytokines examined as compared to acetone, with CCL2 significantly higher in skin from IL-6KO mice. Histological analysis showed that IL-6KO mice displayed significantly more inflammatory cell infiltration as compared to WT and TgIL6 mice in response to jet fuel. Analysis of mRNA for the M2 macrophage marker CD206 indicated a 4-fold decrease in skin of IL-6KO mice treated with either irritant as compared to WT. Taken together, these observations suggest that IL-6 acts in an anti-inflammatory manner during irritant dermatitis, and these effects are dependent on the chemical nature of the irritant.

Succession planning in US pharmacy schools

The deans, associate and assistant deans, and department chairs of a college or school of pharmacy retain historic memories of the institution and share the responsibility for day-to-day operation, sustainability, and future planning. Between the anticipated retirement of baby boomers who are senior administrative faculty members and the steady increase in number of colleges and schools of pharmacy, the academy is facing a shortage of qualified successors. Succession planning involves planning for the effective transition of personnel in leadership positions within an organization. This paper describes the subject of succession planning at a sample population of AACP institutions by obtaining perspectives on the subject from the deans of these institutions via standardized interview instruments. The instruments were utilized with 15 deans; all interview data were blinded and analyzed using analyst triangulation. The majority of deans responded that some level of succession planning was desirable and even necessary; however, none claimed to have a formal succession planning structure in place at his or her home institution. Although widely accepted and well-recognized in the corporate and military sectors, succession planning within pharmacy schools and colleges is neither universally documented nor implemented. Differences exist within the administrative structure of these non-academic and academic institutions that may preclude a uniform succession planning format. While the evidence presented suggests that succession planning is needed within the academy, a concerted effort must be made towards implementing its practice.

Interleukin (IL)-6 modulates transforming growth factor-beta expression in skin and dermal fibroblasts from IL-6-deficient mice

BACKGROUND

Interleukin (IL-6) and transforming growth factor (TGF)-beta have been shown to play a role in skin development and maintenance.

OBJECTIVES

A link between these two cytokines has yet to be identified and therefore in this study we investigated the modulation of TGF-beta1 and TGF-beta type 2 receptor (TGF-betaR2) by IL-6 in skin.

METHODS

An IL-6 knockout (IL-6KO) fibroblast-populated lattice model and intradermal injections of IL-6 into unwounded IL-6KO mice were used to investigate the direct effects of IL-6 treatment on TGF-beta and TGF-betaR2 expression and to determine the signalling mechanism. In addition, IL-6KO and C57BL/6 control mice were wounded by a 4-mm punch biopsy to monitor expression of TGF-beta1 and TGF-betaR2 within a wound over time. The expression of TGF-beta1 and TGF-betaR2 was assessed by real-time quantitative polymerase chain reaction, enzyme-linked immunosorbent assay and immunohistology.

RESULTS

Recombinant IL-6 treatment of IL-6KO lattices and intradermal injections of IL-6 showed a significant induction of TGF-beta1 mRNA and protein, with TGF-beta1 expression localized in the dermis, while TGF-betaR2 expression was primarily in the epidermis in IL-6KO mice. During healing, the expression of TGF-beta1 and TGF-betaR2 mRNA was significantly greater in unwounded and 7-day-old wounds from wild-type mice; however, protein expression did not differ. Treatment with signal transduction inhibitors indicated that IL-6 modulates TGF-beta through a mitogen-activated protein kinase/extracellular signal-regulated kinase (Mapk/Erk)-dependent mechanism.

CONCLUSION

These studies indicate that IL-6 has the ability to modulate the expression of TGF-beta and TGF-betaR2 to varying degrees in the skin, which may provide a possible mechanism for defining the role of IL-6 in skin maintenance and a new association of IL-6 with TGF-beta in pathologies associated with fibrosis.

IL-6 modulates TGF-β expression in skin from IL-6 deficient mice (97.11)

IL-6 and Tgf-β have been shown to play a role in skin development and maintenance. However, a link between these two cytokines has yet to be identified therefore; therefore, in this study we investigated the modulation of Tgf-β1 and Tgf-βR2 by IL-6 in skin. Recombinant IL-6 treatment of IL-6KO lattices and intradermal injections of IL-6 into unwounded mice showed a significant induction of Tgf-β1 mRNA and protein, where Tgf-β1 expression localized in the dermis, while Tgf-βR2 expression resided primarily in the epidermis in IL-6KO mice. IL-6 also increased Tgf-βR2 mRNA and protein expression, and potentiates TGFb mediated decreases in proliferation in cultured keratinocytes. Wounded IL-6KO and C57BL/6 control mice showed Tgf-β1 and βR2 mRNA expression was significantly greater in unwounded and seven day-old wounds from WT mice, however; protein expression was not different. Use of inhibitors indicated that IL-6 modulates Tgf-β through a Mapk/Erk dependent mechanism. These studies indicate that IL-6 has the ability to modulate the expression of Tgf-β and Tgf-βR2 mRNA in dermal fibroblasts and unwounded skin through a Mapk/Erk dependent mechanism. Protein expression levels indicated additional regulation by factors other than IL-6 within the wound. IL-6 treatment also potentiates the differentiative effects of Tgf-β on cultured keratinocytes. These results may provide a possible mechanism defining the role of IL-6 in skin maintenance and may indicate a new association of IL-6 with Tgf-β in pathologies associated fibrosis.

This work was funded by NIH/NIGMS grant R01 GM067745.

Interleukin-6 (IL-6) modulates migration and matrix metalloproteinase function in dermal fibroblasts from IL-6KO mice

BACKGROUND

Interleukin-6-deficient (IL-6KO) mice display significantly delayed cutaneous wound healing characterized by decreased re-epithelialization, granulation tissue and wound closure. Dermal fibroblasts are one of the principal cell types found in granulation tissue and mediate numerous processes during healing.

OBJECTIVES

To investigate the effects that IL-6 might have on granulation tissue formation and fibroblast motility. As fibroblast motility is associated with matrix metalloproteinase (MMP) activity, the expression of MMP-2 and the tissue inhibitors of metalloproteinase (TIMP)-1 and -2 were assessed.

METHODS

Punch biopsies (4 mm) were performed in the skin of IL-6KO and C57BL/6 mice. The expression of MMP-2, TIMP-1 and -2 in wound tissue was monitored over time. Cellular infiltration and granulation tissue formation was monitored by subcutaneous implantation of polyvinyl alcohol (PVA) sponges. A free-floating collagen lattice model was also used to investigate the direct effects of IL-6 treatment on isolated IL-6KO fibroblasts. The expression of MMP-2, and the inhibitors TIMP-1 and -2, were assessed via real-time quantitative polymerase chain reaction and enzyme-linked immunosorbent assay.

RESULTS

IL-6KO wounds showed impaired granulation tissue formation 5 days postwounding and fewer fibroblasts had populated the PVA matrices 7 days after implantation in IL-6KO mice compared with wild-type C57BL/6. The mRNA and protein expression of MMP-2 and TIMP-2 mRNA was increased in IL-6KO mice compared with wild-type mice beyond 1 day postwounding, while the expression of TIMP-1 mRNA was transiently higher in IL-6KO only 3 days postwounding. Treatment of collagen lattices with various concentrations of rmIL-6 again showed a dose-response decrease in mRNA and protein expression of MMP-2 and TIMP-2 protein expression, compared with saline control, while TIMP-1 did not appear to be significantly modulated.

CONCLUSIONS

These results indicate that IL-6 influences the function of fibroblasts in wounds, and one mechanism of this regulation may be through the modulation of MMP-2 and TIMP proteins.

Association of gender and IL-6R function and its role in alcoholic liver disease (B58)

Alcohol liver disease (ALD) is more severe in females than males. Proinflammatory cytokine release from Kupffer cells during inflammation is associated with the pathogenesis of ALD, and female chronically ethanol fed rats express cytokine mediators differently than male counterparts. Differences in IL-6 receptor function in females may play a role in the clinical observations of more severe ALD in females. In this study, the effects of sex steroid exposure on the expression and function of IL-6 receptor in ethanol fed rats were examined. Normal male and female or ovarectomized Wistar rats were fed liquid diet with and without ethanol for up to four weeks. Ovarectomized rats were additionally implanted with osmotic pumps containing either testosterone or estrogen. Ethanol consumption significantly increased in IL-6 receptor mRNA and protein expression and NFkB activation in female and estrogen treated rats. However C/EBPβ and IkB expression was higher in male and testosterone treated rats, indicating increased IL-6 signaling, and decreased NFkB signaling. Our data suggest that sex steroids play a role in IL-6R expression and function and that testosterone may be protective in ALD.

Interleukin 6 modulates genes associated with fibroblast migration and function (101.10)

Interleukin 6 deficient mice (IL-6KO) display significantly delayed cutaneous wound healing, characterized by decreased granulation tissue formation. Dermal fibroblasts are one of the principal cell types found in granulation tissue and mediate numerous processes during healing including collagen deposition. Polyvinyl alcohol sponge matrices implanted seven days in IL-6KO mice showed far fewer infiltrating fibroblasts as compared to wild-type C57. It was also found that full thickness wounds from IL-6KO mice showed higher expression of MMP-2 and TIMP-2 as compared to wild-type from 1 to 5 days post wounding. Treatment of IL-6KO fibroblast populated free-floating collagen lattices with various concentrations of rmIL-6 showed a dose response decrease in MMP-2 TIMP-2 mRNA and protein expression. The expression of TGFβ’s 1, and 3 as well as TGFβRII, which can mediate collagen formation, were increased in IL-6KO mouse skin treated intradermally with rmIL-6 in a dose response manner. Expression of TGFβ1, 3, and RII were induced as well in IL-6KO fibroblast collagen lattice cultures in a similar manner. These results indicate that IL-6 may influence on collagen deposition during granulation tissue formation in skin wounds. The mechanism of this may involve both the inhibition of MMP function, and the induction of TGFβ genes.

This research was supported by a grant from NIH/NIGMS (5R01GM067745-03).

IL-6 modulates alpha-smooth muscle actin expression in dermal fibroblasts from IL-6-deficient mice

IL-6 deficient (IL-6KO) mice display significantly delayed cutaneous wound closure. Myofibroblasts are the primary mediators of wound closure, and alpha-smooth muscle actin (alpha-SMA) is a marker of fibroblast differentiation to the myofibroblast phenotype. Wounds from IL-6KO, and wild-type mice were collected up to 6 days following wounding. Expression of alpha-SMA mRNA was found to be increased in wounds of IL-6KO mice up to 48 hours post wounding, but decreased below wild-type levels by 72 hours. Recombinant IL-6 treatment of IL-6KO dermal fibroblasts showed an induction of alpha-SMA mRNA and protein peaking at 1 ng/ml cytokine, but declining at higher concentrations. Actinomycin-D treatment of fibroblast cultures indicated that recombinant mouse IL-6 (rmIL-6) induction of alpha-SMA mRNA appeared to be primarily transcriptionally regulated, and extracellular signal-regulated kinase 1/2 kinase, but not signal transducers and activators of transcription 3 was readily phosphorylated in rmIL-6 treated IL-6KO fibroblasts. A dose-response increase in the mRNA expression of the IL-6R signaling inhibitor protein suppressors of cytokine signaling (SOCS) 3 was also noted in rmIL-6-treated IL-6KO fibroblasts. These data indicate that alpha-SMA expression is dysregulated in IL-6KO mice. The expression of alpha-SMA induced by rmIL-6 in fibroblasts from IL-6KO mice appears to be transcriptionally modulated, dependent on JAK1 kinase, and possibly downregulated as a result of increased SOCS3 expression.

Stress induced in heart and other tissues by rat dermal exposure to JP-8 fuel

Limited information is available regarding the development of systemic organ stress by dermal exposure to JP-8 fuel. In this study, the systemic stress potential of this fuel is evaluated in a rat model subjected to dermal applications of JP-8 for 7 days at 300 microl per day. Tissue histology indicated that JP-8 induces morphological alterations that suggest that tissue stress in the heart is more substantial than stress in the kidney and liver. Immunoblot analysis of tissues revealed increased levels of the inducible heat shock protein 70 (HSP70) in the heart, kidney, and liver after this dermal JP-8 exposure. This exposure also leads to increased levels of heme oxygenase-1 (HO-1/HSP3) in the liver. Additionally during this exposure, a negative regulator of inflammation, IkappaBalpha (inhibitor of NF-kappaB), was increased in the liver, slightly increased in the kidney, and not increased in the heart. Two regions of the rat brain were also examined and HSP70 and IkappaBalpha were increased in the cerebellum but not significantly increased in the cortex. This study indicates dermal JP-8 exposure causes systemic alterations that are associated with cytoprotective activities (e.g., in the liver) as well as potentially toxic mechanisms (heart and kidney).

JP-8 jet fuel exposure induces inflammatory cytokines in rat skin

The Department of Defense (DoD) has identified that one of the main complaints of personnel exposed to JP-8 jet fuel is irritant dermatitis. The purpose of this investigation is to describe the JP-8-induced inflammatory cytokine response in skin. JP-8 jet fuel or acetone control (300 microl) was applied to the denuded skin of rats once a day for 7 days. Skin samples from the exposed area were collected 2 and 24 h after the final exposure. Histological examination of skin biopsies showed neutrophilic inflammatory infiltrate. Reverse transcription-polymerase chain reaction (RT-PCR) was performed utilizing skin total RNA to examine the expression of various inflammatory cytokines. The CXC chemokine GROalpha was significantly upregulated at both time points, whereas GRObeta was only increased 2 h post final exposure. The CC chemokines MCP-1, Mip-1alpha, and eotaxin were induced at both time points, whereas Mip-1beta was induced only 24 h post exposure. Interleukins-1beta and -6 (IL-1beta and IL-6) mRNAs were significantly induced at both time points, while TNFalpha was not significantly different from control. Enzyme-linked immunosorbent assay (ELISA) of skin protein confirmed that MCP-1, TNFalpha, and IL-1beta were modulated as indicated by PCR analysis. However, skin IL-6 protein content was not increased 2 h post exposure, whereas it was significantly upregulated by jet fuel after 24 h. Data from the present study indicate that repeated (7 days) JP-8 exposure induces numerous proinflammatory cytokines in skin. The increased expression of these cytokines and chemokines may lead to increased inflammatory infiltrate in exposed skin, resulting in JP-8-induced irritant dermatitis.

Differential expression of liver interleukin-6 receptor-alpha in female versus male ethanol-consuming rats

BACKGROUND

It is well known that women are more susceptible to alcoholic liver disease (ALD) than men, and inflammation is thought to play a major role in alcohol-induced liver injury. Increased circulating levels of the proinflammatory cytokine interleukin (IL)-6 are a marker for serious ALD in humans. However, IL-6 also has protective effects, such as induction of liver regeneration and inhibition of hepatocyte apoptosis. Although the roles of IL-6 in ALD have begun to be established, little is known about the expression of its receptor (IL-6Ralpha) during chronic alcohol administration.

METHODS

Male and female rats were intragastrically fed ethanol or control isocaloric liquid diet for 2 and 4 weeks. Liver samples were collected, and gene expression was assessed by reverse transcription-polymerase chain reaction and Western blot.

RESULTS

Herein, we show clear gender differences in alcohol-induced liver IL-6Ralpha expression. Analysis of rat liver samples showed that ethanol consumption significantly increased IL-6Ralpha messenger RNA and protein expression in females as compared with similarly treated males after 2 and 4 weeks. Increased STAT3 phosphorylation in the livers of ethanol-consuming females also indicated greater IL-6Ralpha activation in these animals. Conversely, ethanol-consuming males displayed increased IkappaB messenger RNA and protein expression, which may inhibit IL-6R expression, compared with females.

CONCLUSIONS

Given the association of inflammation with ethanol-induced liver damage, these data may offer insight into a possible mechanism by which females develop more severe ALD than males.

Interleukin 6 Indirectly Induces Keratinocyte Migration

IL-6-deficient transgenic mice (IL-6 KO) display significantly delayed cutaneous wound healing. To further elucidate the role of IL-6 in skin wound healing, epidermal keratinocyte and dermal fibroblast cells were isolated from neonatal IL-6 KO mice and treated with rmIL-6. It was found that rmIL-6 alone did not significantly modulate the proliferation or migration of cultured IL-6 KO keratinocytes. rmIL-6, however, significantly induced the migration of IL-6 KO keratinocytes (up to 5-fold) when co-cultured with dermal fibroblasts. Culture supernatants from IL-6-treated fibroblasts were also found to induce the migration of keratinocytes to a similar degree. Genomics analysis of treated fibroblasts indicated that rmIL-6 does not induce any known soluble keratinocyte migratory factors. rmIL-6 treatment of fibroblast, however, induced a rapid and sustained phosphorylation of STAT3 protein. These data indicate that IL-6 could influence wound healing by inducing keratinocyte migration through the production of a soluble fibroblast-derived factor, and its activity may be associated with STAT3 activation.

The role of tumor necrosis factor-alpha in liver toxicity, inflammation, and fibrosis induced by carbon tetrachloride

Hepatic expression of the proinflammatory cytokine tumor necrosis factor-alpha (TNFalpha) occurs in many acute and chronic liver diseases, as well as following exposure to hepatotoxic chemicals, and is believed to help influence both the damage and repair processes that occur following these insults by regulating additional mediators. We examined the role of TNFalpha in transgenic mice deficient in TNF receptors (TNFR) utilizing carbon tetrachloride (CCl(4)) as a model hepatotoxic agent that allowed for the evaluation of necrosis, inflammation, and fibrosis. Hepatocyte damage, as evident by local areas of liver necrosis and elevated levels of serum transaminase, occurred to a similar degree in wild-type and TNFR-deficient knockout (KO) mice following acute exposure to CCl(4). In contrast, the inflammatory response, manifested as an inflammatory cell influx, as well as induction of chemokines and adhesion molecules that occurred in wild-type mice following treatment with CCl(4), was not as evident in TNFR-KO mice. This response was associated primarily with type-1 (TNFR1) rather than type-2 (TNFR2) receptor responses. Liver fibrosis resulting from chronic CCl(4) exposure was also markedly dependent upon TNFalpha as demonstrated by almost a complete histological absence of fibrosis in TNFR-deficient mice. This was further supported by marked reductions in procollagen and transforming growth factor beta synthesis in TNFR-deficient mice. Taken together, these results indicate that TNFalpha is responsible for regulating products that induce inflammation and fibrosis but not direct hepatocyte damage in CCl(4)-induced hepatotoxicity.

Regulation and role of interleukin 6 in wounded human epithelial keratinocytes

Dermal wounding is accompanied by inflammation and the resulting proinflammatory cytokines, including interleukin (IL)-6, are thought to play an important role in the repair process. IL-6 is produced by normal human keratinocytes to various dermatological diseases and we have recently shown it is also required for normal wound repair. However, neither the events responsible for its induction nor its role in repair have been clearly identified. Using a recently developed in vitro wounding model, we demonstrate that IL-6 mRNA is expressed and immunoreactive IL-6 is released from cultures of human epidermal keratinocytes (NHEKs) following wounding. The transcription factors, NF kappa B and NF-IL-6 (C/EBP beta), which coordinately help regulate IL-6 expression, were activated following wounding and preceded the appearance of IL-6. Addition of IL-1 alpha to NHEK cultures increased IL-6 production and activated NF kappa B and C/EBP beta. Addition of the IL-1 alpha receptor antagonist inhibited both IL-6 mRNA expression and the transcription factors following wounding. Immunoreactive IL-1 alpha was detected in the medium following wounding in the absence of new message. Furthermore, addition of IL-6 to NHEK cultures decreased the expression of keratins 1 and 10, differentiation markers of keratinocytes, while proliferation was not affected. Taken together, these data indicate that constitutive keratinocyte-derived IL-1 alpha is a stimulus for IL-6 production in wounded epidermis, the response involves NF kappa B and C/EBP beta transcription factors, and IL-6 may be associated with modulation of keratinocyte differentiation rather than proliferation.

Interleukin-6 treatment augments cutaneous wound healing in immunosuppressed mice

It has been postulated that the inflammatory response that occurs after cutaneous wounding is a prerequisite for healing and that inflammatory cytokines, such as interleukin-6 (IL-6) are involved in this process. We showed previously that IL-6-deficient mice display delayed wound healing, which could be reversed by administration of a murine IL-6 expression plasmid or recombinant murine IL-6 (rMuIL-6). In the present study, we observed that delayed cutaneous wound healing, which occurs as a result of glucocorticoid-induced immunosuppression, can also be reversed by rMuIL-6, as evidenced by epithelialization, granulation tissue formation, and wound closure. In vehicle control mice, rMuIL-6 did not augment healing but rather delayed the process. Immunochemical studies indicated that the expression of matrix metalloproteinase-10 (MMP-10) was increased in dexamethasone-treated mice and that rMuIL-6 treatment reduced its expression, indicating that IL-6 may influence dermal matrix formation and, specifically, collagen synthesis. These results demonstrate that IL-6 can restore abnormal wound repair that occurs in immunodeficiency and suggest its use as a potential therapy.

Role of inflammation in chemical-induced hepatotoxicity

The liver, which is the major organ responsible for the metabolism of drugs and toxic chemicals, is also the primary target organ for many toxic chemicals. Increasing evidence has indicated that inflammatory processes are intimately involved in chemical-induced hepatotoxic processes, and like other inflammatory diseases, such as autoimmunity, are responsible for producing mediators that can effect liver damage or repair. This review will summarize our current understanding of how inflammatory processes influence hepatic pathology and repair following exposure to established hepatotoxic chemicals including carbon tetrachloride, an industrial chemical, and acetaminophen, a widely used analgesic.

The role of tumor necrosis factor alpha in chemical-induced hepatotoxicity

Only recently have toxicologists come to understand the role of inflammation, and TNFalpha specifically, in classical toxicological processes. This relationship appears fairly complex, as inflammation and proliferation may well be only one facet of a time- and dose-dependent continuum of toxicological and repair processes. Not surprisingly, considerable efforts are being undertaken using our newly found understanding of molecular control to develop specific and safe chemical, biological, and molecular regulators of TNFalpha for potential therapeutic use. Their effectiveness in controlling environmental or occupational diseases has yet to be established.

Impaired cutaneous wound healing in interleukin-6-deficient and immunosuppressed mice

It has been postulated that an inflammatory response after cutaneous wounding is a prerequisite for healing, and inflammatory cytokines, such as interleukin-6 (IL-6), might be intimately involved in this process. IL-6-deficient transgenic mice (IL-6 KO) displayed significantly delayed cutaneous wound healing compared with wild-type control animals, requiring up to threefold longer to heal. This was characterized by minimal epithelial bridge formation, decreased inflammation, and granulation tissue formation. Using electrophoretic mobility shift assays of wound tissue from IL-6 KO mice, decreased AP-1 transcription factor activation was shown compared with wild-type mice 16 h after wounding. In situ hybridization of wound tissue from wild-type mice revealed IL-6 mRNA expression primarily in the epidermis at the leading edge of the wound. Delayed wound healing in IL-6 KO mice was reversed with a single dose of recombinant murine IL-6 or intradermal injection of an expression plasmid containing the full-length murine IL-6 cDNA. Treatment with rmIL-6 also reconstituted wound healing in dexamethasone-treated immunosuppressed mice. The results of this study may indicate a potential use for IL-6 therapeutically where cutaneous wound healing is impaired.

Immunotoxicology: role of inflammation in chemical-induced hepatotoxicity

The liver, which is the major organ responsible for the metabolism of drugs and chemicals, is also the primary target organ for many toxic chemicals. Increasing evidence has indicated that inflammatory processes are intimately involved in chemical-induced hepatotoxic processes, and like other inflammatory diseases, such as autoimmunity, are responsible for producing mediators which can effect liver damage or repair. This review will summarize the authors' current understanding of how inflammatory processes influence hepatic pathology and repair following exposure to established hepatotoxic chemicals including carbon tetrachloride (CCl4), an industrial chemical, and acetaminophen (APAP), a widely used analgesic.

The modulation of B16BL6 melanoma metastasis is not directly mediated by cytolytic activity of natural killer cells in alcohol-consuming mice

BACKGROUND

Previous studies in our laboratory indicate that alcohol consumption suppresses the metastasis of B16BL6 melanoma, whereas the cytolytic activity of natural killer (NK) cells is decreased in female C57BL/6 mice given 20% w/v alcohol in their drinking water. In the present study, we further evaluated the involvement of NK cells and alcohol consumption in the cytolytic activity of NK cells, the surface expression of NK phenotypic markers, and metastasis of B16BL6 melanoma in C57BL/6 beige (bgJ/bgJ) mutant mice, which possess inherently low NK-cell cytolytic activity.

METHODS

Beige and control (bgJ/+) mice were given either water or 20% w/v of alcohol in drinking water for 6 1/2 to 7 weeks before assay for cytolytic activity, surface marker expression, and inoculation with B16BL6 melanoma intravenously or into the pinna of the ear.

RESULTS

NK cytolytic activity was suppressed in beige mice, and alcohol consumption did not modulate further the cytolytic activity. Beige mice had a lower percentage of NK cells in the peripheral blood and spleen than control mice. Peripheral blood lymphocytes from beige mice also exhibited a reduced percentage of CD4+ T lymphocytes. Alcohol consumption similarly reduced the percentages of NK1.1- and LGL-1-expressing lymphocytes in the peripheral blood and spleen and reduced the percentage of CD8+ T lymphocytes in the peripheral blood in both control and beige mice. Tumor lung colonization was increased in beige mice relative to control mice after intravenous inoculation of B16BL6 melanoma. The increase was more pronounced in water-drinking beige mice than in control mice irrespective of alcohol consumption. Tumor lung colonization was significantly decreased (p < 0.05) by alcohol consumption in one experiment and partially decreased (p = 0.07) in the other. Mice that were inoculated into the pinna of the ear also exhibited a blunted antimetastatic response to alcohol consumption.

CONCLUSIONS

These data suggest that the presence of the beige mutation diminishes the antimetastatic effect of alcohol consumption and that there is no interaction between alcohol consumption and NK-cell activity in the modulation of lung metastasis of B16BL6 melanoma cells.

TNF-alpha regulates transforming growth factor-alpha expression in regenerating murine liver and isolated hepatocytes

TNF-alpha is a pleotropic proinflammatory cytokine that has been implicated as a contributing factor in a number of disease processes, primarily through its ability to induce the expression of inflammatory and cytotoxic mediators. TNF-alpha is also involved in cell growth accompanying the healing process in multiple organ systems and influences liver repair following hepatotoxic damage or regeneration following partial hepatectomy. In this respect, TNF-alpha is a known mitogen for hepatocytes. In this paper we describe a novel role for TNF-alpha in the modulation of expression of TGF-alpha, the latter being a complete hepatocyte mitogen. TNF-alpha directly up-regulates TGF-alpha mRNA by up to 7-fold in isolated mouse hepatocytes, whereas neutralization of TNF-alpha significantly decreased liver mRNA and protein expression of TGF-alpha following chemical-induced hepatotoxicity. That TNF-alpha directly stimulated TGF-alpha was suggested by the inability of either anti-IL-6 Abs or cycloheximide to inhibit TNF-alpha-induced TGF-alpha expression in hepatocytes. However, in the presence of anti-TGF-alpha neutralizing Abs, the mitogenic activity of TNF-alpha is abrogated. Using cells transfected with the TGF-alpha promoter, and an RNA polymerase inhibitor, it was shown that TNF-alpha modulates TGF-alpha expression through both pre- and posttranscriptional events. Taken together, these data suggest that TNF-alpha participates in liver repair and regeneration, in part, by directly inducing the expression of TGF-alpha.

Essential role of tumor necrosis factor alpha in alcohol-induced liver injury in mice

BACKGROUND & AIMS

Tumor necrosis factor (TNF)-alpha is associated with increased mortality in alcoholics, but its role in early alcohol-induced liver injury is not fully understood. Recently, it was shown that injury induced by the enteral alcohol delivery model of Tsukamoto and French was reduced by antibodies to TNF-alpha. To obtain clear evidence for or against the hypothesis that TNF-alpha is involved, we studied TNF receptor 1 (TNF-R1, p55) or 2 (TNF-R2, p75) knockout mice.

METHODS

Long-term enteral alcohol delivery was modified for male gene-targeted mice lacking TNF-R1 and TNF-R2. Animals were given a high-fat liquid diet continuously with either ethanol or isocaloric maltose-dextrin as a control for 4 weeks.

RESULTS

Ethanol elevated serum levels of alanine aminotransferase nearly 3-fold in wild-type and TNF-R2 knockout mice but not in TNF-R1 knockout mice. Likewise, ethanol caused severe liver injury in wild-type mice (pathology score, 5.5 +/- 0.6) and TNF-R2 knockout mice (pathology score, 5.0 +/- 0.4), but not in TNF-R1 knockout mice (pathology score, 0.8 +/- 0.4; P < 0.001).

CONCLUSIONS

Long-term ethanol feeding caused liver injury in wild-type and TNF-R2 knockout mice but not in TNF-R1 knockout mice, providing solid evidence in support of the hypothesis that TNF-alpha plays an important role in the development of early alcohol-induced liver injury via the TNF-R1 pathway. Moreover, the long-term enteral ethanol feeding technique we described for the first time for knockout mice provides a useful new tool for alcohol research.

Essential role of tumor necrosis factor alpha in alcohol-induced liver injury in mice

BACKGROUND & AIMS

Tumor necrosis factor (TNF)-alpha is associated with increased mortality in alcoholics, but its role in early alcohol-induced liver injury is not fully understood. Recently, it was shown that injury induced by the enteral alcohol delivery model of Tsukamoto and French was reduced by antibodies to TNF-alpha. To obtain clear evidence for or against the hypothesis that TNF-alpha is involved, we studied TNF receptor 1 (TNF-R1, p55) or 2 (TNF-R2, p75) knockout mice.

METHODS

Long-term enteral alcohol delivery was modified for male gene-targeted mice lacking TNF-R1 and TNF-R2. Animals were given a high-fat liquid diet continuously with either ethanol or isocaloric maltose-dextrin as a control for 4 weeks.

RESULTS

Ethanol elevated serum levels of alanine aminotransferase nearly 3-fold in wild-type and TNF-R2 knockout mice but not in TNF-R1 knockout mice. Likewise, ethanol caused severe liver injury in wild-type mice (pathology score, 5.5 +/- 0.6) and TNF-R2 knockout mice (pathology score, 5.0 +/- 0.4), but not in TNF-R1 knockout mice (pathology score, 0.8 +/- 0.4; P < 0.001).

CONCLUSIONS

Long-term ethanol feeding caused liver injury in wild-type and TNF-R2 knockout mice but not in TNF-R1 knockout mice, providing solid evidence in support of the hypothesis that TNF-alpha plays an important role in the development of early alcohol-induced liver injury via the TNF-R1 pathway. Moreover, the long-term enteral ethanol feeding technique we described for the first time for knockout mice provides a useful new tool for alcohol research.

Functional asymmetries in the quality of handwriting movements: a kinematic analysis

Writing hand preference is a prominent functional asymmetry, but biomechanical factors may also contribute to any kinematic differences in the quality of handwriting movements performed by either hand. Eighteen dextral participants used a noninking pen with their right or left hand to write cursive letter ls, inverted ls, and their mirror images (to control for biomechanical differences) on a graphics tablet. Kinematic analysis of the scaling, consistency, efficiency, and shape of writing stroke trajectories revealed functional asymmetries between hands. The right hand was faster and produced more efficient strokes, which were of more consistent length, duration, and peak velocity. Differences between hands do not simply reflect biomechanical factors; therefore, the documentation of any functional asymmetries may allow their subsequent use as markers of underlying pathology in conditions such as schizophrenia.

Functional asymmetries in the quality of handwriting movements: a kinematic analysis

Writing hand preference is a prominent functional asymmetry, but biomechanical factors may also contribute to any kinematic differences in the quality of handwriting movements performed by either hand. Eighteen dextral participants used a noninking pen with their right or left hand to write cursive letter ls, inverted ls, and their mirror images (to control for biomechanical differences) on a graphics tablet. Kinematic analysis of the scaling, consistency, efficiency, and shape of writing stroke trajectories revealed functional asymmetries between hands. The right hand was faster and produced more efficient strokes, which were of more consistent length, duration, and peak velocity. Differences between hands do not simply reflect biomechanical factors; therefore, the documentation of any functional asymmetries may allow their subsequent use as markers of underlying pathology in conditions such as schizophrenia.

Response (re-)programming in aging: a kinematic analysis

BACKGROUND

Age-related motor slowing may reflect either motor programming deficits, poorer movement execution, or mere strategic preferences for online guidance of movement. We controlled such preferences, limiting the extent to which movements could be programmed.

METHODS

Twenty-four young and 24 older adults performed a line drawing task that allowed movements to be prepared in advance in one case (i.e., cue initially available indicating target location) and not in another (i.e., no cue initially available as to target location). Participants connected large or small targets illuminated by light-emitting diodes upon a graphics tablet that sampled pen tip position at 200 Hz.

RESULTS

Older adults had a disproportionate difficulty initiating movement when prevented from programming in advance. Older adults produced slower, less efficient movements, particularly when prevented from programming under greater precision requirements.

CONCLUSIONS

The slower movements of older adults do not simply reflect a preference for online control, as older adults have less efficient movements when forced to reprogram their movements. Age-related motor slowing kinematically resembles that seen in patients with cerebellar dysfunction.

Antibodies to tumor necrosis factor alfa attenuate hepatic necrosis and inflammation caused by chronic exposure to ethanol in the rat

Tumor necrosis factor (TNF)alpha, a pivotal cytokine involved in inflammation, is produced primarily by Kupffer cells in the liver. It has been shown that inactivation of Kupffer cells prevents alcohol-induced liver injury; therefore, the purpose of this study was to determine if neutralizing anti-TNF-alpha antibody is also effective. Male Wistar rats were exposed to ethanol (11 to 12 g x kg(-1) x d[-1]) continuously for up to 4 weeks via intragastric feeding using an enteral feeding model. Before ethanol exposure, polyclonal anti-mouse TNF-alpha rabbit serum was injected (2.0 mg/kg intravenously). There were no significant differences in body weight, mean ethanol concentration, or cyclic patterns of ethanol in urine when ethanol- and ethanol plus antibody-treated groups were compared. Expression of TNF-alpha and macrophage inflammatory protein 2 (MIP-2) messenger RNA (mRNA), determined using reverse transcription-polymerase chain reaction, was three- to four-fold higher in livers of ethanol-treated rats than in those of rats fed an ethanol-free, high-fat control diet. In addition, MIP-2 levels were also elevated when detected by Northern blot analysis. Anti-TNF-alpha antibody did not affect expression of mRNA for interleukin (IL) 1alpha, IL-6, transforming growth factor beta1, or TNF-alpha. However, MIP-2 mRNA expression, which is regulated by TNF-alpha, was decreased significantly by anti-TNF-alpha antibody treatment. Serum aspartate transaminase levels were elevated in ethanol-treated rats to 136 +/- 12 IU/L after 4 weeks but only reached 90 +/- 5 IU/L (P < .05) in rats treated with anti-TNF-alpha antibody. The hepatic inflammation and necrosis observed in ethanol-fed rats were attenuated significantly by antibody treatment, and steatosis was not. These results support the hypothesis that TNF-alpha plays an important role in inflammation and necrosis in alcohol-induced liver injury and that treatment with anti-TNF-alpha antibody may be therapeutically useful in this disease.

Modulation of NK cell cytolytic activity by macrophages in chronically exercise-stressed mice

This study was designed to investigate the effects of moderate-intensity endurance training on basal natural killer (NK) cell cytolytic activity in murine splenocytes that were enriched for 1) NK1.1+ cells or 2) macrophages and NK1.1+ cells. Mice were assigned to sedentary (Sed), treadmill control (TM), or treadmill-trained (Trn) groups. Splenocyte number, the percentages of NK1.1+, large granular lymphocytes (NK1.1+, LGL-1+), and other subpopulations did not change in Trn mice. Approximately 70% of cells enriched for NK1.1+ expressed this surface antigen. Lytic units (LU) expressed per LGL-1+ cell were significantly lower in Trn [83.9 +/- 3.2 (SE)] compared with Sed (109.5 +/- 7.5) and TM (101.3 +/- 6.4) groups. When macrophages remained in the in vitro assay, LU per LGL-1(+) cell did not differ across groups. The results indicate that highly enriched NK1.1+ cells from Trn mice had lower NK cell activity compared with Sed mice. No differences in NK cell activity were observed when cells were enriched for NK1.1+ cells and macrophages. These findings support the hypothesis that macrophage modulation of NK cells may be one mechanism contributing to augmented basal NK cell activity in endurance-trained individuals.

Ethanol consumption suppresses the IL2-induced proliferation of NK cells

Ethanol (20% w/v) given to female, C57BL/6 mice in their drinking water suppresses natural killer (NK) and lymphokine activated killer cell cytolytic activity in mixed splenocytes and in splenocytes highly enriched for NK cells. The present study examined the effects of ethanol consumption on rIL2-induced proliferation of enriched NK cells. Mice were given 20% w/v ethanol in the drinking water for 2 weeks. Splenic NK cells were harvested and enriched up to 88% based on surface expression of NK1.1. The enriched NK cells were cultured in the presence of 1000 IU/ml (20 pg/ml) murine recombinant interleukin 2 (rIL2). There were fewer cells (p < 0.02) from ethanol-consuming mice compared to cells from water-drinking control mice after incubation with IL2 at 2, 4, and 6 days of culture. Ethanol consumption was associated with significantly lower [3H]thymidine uptake (p < 0.05). Ethanol consumption did not affect apoptosis or intracellular levels of interferon-gamma, tumor necrosis factor-alpha, or granulocyte macrophage colony-stimulating factor in NK cells. Ethanol consumption did not affect the expression of c-myc mRNA in NK cells that were cultured for 10 min or 4, 8, and 18 hr in rIL2. Suppression of IL2-induced NK cell proliferation is associated with ethanol consumption, and suppression is not due to altered IL2 receptor expression, increased apoptosis, intracellular cytokine levels, or c-myc expression.

Ethanol consumption reduces the cytolytic activity of lymphokine-activated killer cells

Ethanol (20% w/v) given to female C57BL/6 mice in their drinking water reduces splenic natural killer (NK) cell cytolytic activity after 2, 4, and 10 weeks of consumption. This reduction is transient because the levels of NK cell cytotoxicity from ethanol-consuming mice are nearly equal to those of water-drinking mice after splenocytes were incubated in 1000 IU/ml of recombinant interleukin-2 (rIL2) for 16-18 hr. In this study, mice were given 20% w/v ethanol in the drinking water for 2 weeks. Splenic NK cells were enriched up to 88% by negative selection based on surface expression of NK1.1. Enriched NK cells were expanded in rIL2 for 6 days. Lymphokine-activated killer (LAK) cells from both ethanol-consuming and water-drinking mice were > 95% NK1.1+. LAK cell cytolytic activity was significantly lower against NK-insensitive P815 mastocytoma [6.67 +/- 2.18 vs. 17.21 +/- 1.8 lytic units (LUs), p < 0.01], moderately NK-sensitive B16 melanoma (25.3 +/- 6.6 vs. 66.2 +/- 14.2 LU, p < 0.05), and NK-sensitive YAC-1 lymphoma targets (80.5 +/- 34.7 vs. 177.0 +/- 43.6 LU, p < 0.005) in cells from ethanol-consuming mice compared with water-drinking controls. Ethanol consumption did not affect the morphology or phenotype of LAK cells with respect to surface expression of NK1.1, B220, CD3, CD25, CD11a, CD54, CD45RB, or class I major histocompatibility complex.

Effects of ethanol consumption on enriched natural killer cells from C57BL/6 mice

Ethanol (20% w/v) given to female, C57BL/6 mice in their drinking water was previously shown to suppress natural killer (NK) cell cytolytic activity in a mixed splenocyte population. The present study was designed to examine the hypothesis that ethanol consumption independently results in inhibition of NK cell cytolytic activity. Mice were given 20% w/v ethanol in the drinking water for 2 weeks, and splenic NK cells were enriched up to 88% based on surface expression of NK1.1. Cytolytic activity of these freshly enriched NK cells from ethanol-consuming mice against YAC-1 lymphoma cells was inhibited an average of 41% relative to water-drinking controls. Cytolytic activity of enriched NK cells from ethanol-consuming mice was stimulated to levels equal to control water-drinking mice after 16- to 18-hr incubation in 1000 units/ml recombinant interleukin 2. These data indicate that in vitro cytolytic activity of NK cells from ethanol-consuming mice is inhibited in the absence of other modulatory leukocytes.

Mechanistic differences in NK cell cytolytic activity in treadmill-trained and chronic ethanol-consuming mice

The present study was undertaken to investigate mechanisms contributing to differences in natural killer (NK) cell activity in moderately endurance-trained and ethanol-consuming mice. Independent of ethanol exposure, NK cell activity in nylon wool-nonadherent (NWNA) splenocytes is lower in trained than in sedentary control mice (Blank et al. J. Appl. Physiol. 72: 8-14, 1992). Reduced activity may result from a generalized loss of cytolytically active cells, redistribution of NK cells from the spleen to other body compartments, or disruption of paracrine regulation of NK cells after removal of nylon wool-adherent cells. To examine these possibilities, NK cell cytolytic activity was determined in nonenriched splenocytes from treadmill-trained and ethanol-consuming mice. Lymphocyte subpopulations in nonenriched splenocytes and NWNA splenocytes were also compared. Peripheral blood lymphocyte subpopulations were determined to examine combined effects of training and ethanol intake on regional distribution of lymphocytes in blood and spleen. NK cell activity in nonenriched splenocytes from trained water-drinking mice was not reduced compared with that in sedentary mice; rather, cytolytic activity was moderately enhanced (17% increase in lytic units, P < 0.05). Training did not change percentages of T-cells, B-cells, and NK [NK1.1+ and large granular lymphocytes (LGL-1+)] cells or the LGL/NK ratio in the spleen and blood. NK cell cytolytic activity was significantly reduced in nonenriched splenocytes from ethanol-consuming mice, independent of training. These findings support the hypothesis that moderate-intensity endurance training influences splenic NK cell function by modulating paracrine regulation of NK cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Ethanol-induced changes in peripheral blood and splenic natural killer cells

Previous work demonstrated that splenic natural killer (NK) cell cytolytic activity was suppressed in ethanol-consuming mice within 1 week and for as long as 10 weeks concurrent with ethanol intake. However, it is unknown if suppression of NK cell activity with ethanol consumption results from regional losses in NK cells. The present experiments were designed to examine the effects of ethanol on the percentage and total number of NK cells in the spleen and blood. Data indicate that, after 4 weeks of ethanol intake, NK cell activity of peripheral blood lymphocytes was also suppressed (50% of controls). With short-term (2-week) exposure, the percentage of NK cells in the blood and the spleen remained relatively constant. In the spleen, changes in the number of NK cells reflected generalized fluctuations in lymphocyte numbers rather than variation in the percentage of NK cells. NK cells were most sensitive to the effects of ethanol during long-term (8-week) ethanol intake, as demonstrated by significant reductions in the total percentage of NK1.1+ cells in the blood, and the LGL-1+ subset in the blood and spleen. These results provide insight into the mechanism of NK modulation by ethanol. Because NK cells were not selectively depleted after 2-4 weeks of ethanol intake, loss of cytolytically active NK cells cannot explain the suppression of in vitro cytolytic activity of cells from ethanol-consuming mice. However, with prolonged ethanol intake (8 weeks), the depletion of NK cells, specifically the LGL-1+ subset, may contribute to the overall suppression of NK cell cytolytic function.

Alcohol consumption suppresses metastasis of B16-BL6 melanoma in mice

Female C57BL/6 mice were fed a defined, pelleted diet and given 10% w/v or 20% w/v ethanol in their drinking water. Natural killer (NK) cell cytolytic activity was compared between water-drinking and ethanol-consuming mice and in mice that were also treated with polyinosinic-polycytidylic acid (poly I:C) to augment NK cell activity or with anti-NK1.1 antibody to decrease activity. NK cell cytolytic activity was not altered in mice given 10% ethanol, but was decreased in mice given 20% ethanol compared to water-drinking mice. Poly I:C treatment increased and anti-NK1.1 antibody treatment decreased NK cell activity in both water-drinking and 20% ethanol-consuming mice. Experimental and spontaneous metastases of B16-BL6 melanoma were evaluated as a function of the duration of ethanol consumption before tumor inoculation and as a function of altered NK cell activity. Experimental metastasis was inhibited after 4 and also after 6.5 weeks of ethanol exposure. Poly I:C treatment inhibited tumor lung colonization irrespective of ethanol consumption. Anti-NK1.1 antibody treatment increased metastasis, although to a lesser degree in mice consuming 10% ethanol. Spontaneous metastasis was inhibited in mice consuming 10% ethanol for 4 weeks, and in mice consuming 20% ethanol for 1 and 4 weeks before melanoma inoculation.