Heat shock protein 27 inhibits apoptosis in human neutrophils.

BACKGROUND: Prolonged neutrophil(PMN) survival has been implicated in tissue injury following sepsis. A variety of bacterial products have been identified which inhibit PMN apoptosis including lipopolysaccharide(LPS). Extracellular heat shock proteins(Hsp) have recently been identified as potent regulatory signals for the innate immune system during the inflammatory response. We hypothesized that Hsp 27 can affect PMN phenotype with respect to apoptosis and cytokine profile. MATERIALS AND METHODS: PMN were isolated from the peripheral blood of healthy human volunteers by red blood cell sedimentation and gradient centrifugation. Cells were placed in media and cultured for 18 h with and without recombinant human Hsp 27 at various concentrations. In parallel experiments, PMN were stimulated with LPS, a known inhibitor of PMN apoptosis, for comparison. Apoptosis was quantified using annexin V and propidium iodide staining with flow cytometric analysis. Culture supernatants were assayed for secretion of TNF-alpha, IL-10, and IL-12. RESULTS: Hsp 27 significantly inhibits PMN apoptosis [control; 81.8 +/- 3.6%, vs Hsp 27, 60.4 +/- 4.1% p < 0.05]. The reduction is similar to that signaled by LPS, alone. Together their effect is not synergistic. The Hsp 27 response is dose-dependent. Hsp 27 does not induce secretion of TNF-alpha, IL-10, or IL-12, whereas LPS does signal IL-12 and TNF-alpha secretion. CONCLUSION: These data demonstrate that exogenous Hsp 27 may play a role in neutrophil-mediated tissue injury during trauma and sepsis via its ability to inhibit neutrophil apoptosis. However, Hsp 27 does not significantly alter neutrophil phenotype with respect to cytokine production profile.

Loss of chemokine SDF-1alpha-mediated CXCR4 signalling and receptor internalization in human hepatoma cell line HepG2.

Expression of the chemokine stromal cell-derived factor-1alpha (SDF-1alpha) is absent from many carcinomas, including hepatomas. We note an early signalling defect in the hepatocellular carcinoma (HCC) cell line HepG2 that expresses the CXCR4 receptor and binds biotin-labelled SDF, but fails to stimulate downstream signalling events after engagement with SDF. In HepG2, the SDF/CXCR4 interaction did not result in calcium influx, phosphorylation and internalization of CXCR4, nor in a rapid phosphorylation of p44/42 MAP kinase. There were no CXCR4 mutations in the second chemokine binding loop or C terminal phosphorylation and internalization domains. The downstream signalling machinery in HepG2 appears to be intact since transfection of wild-type CXCR4 restored functional responsiveness. We conclude that HepG2 is unresponsive to SDF stimulation because of a defect located after receptor binding but before the activation of the signalling cascade. A hypothetical blocking molecule could hinder receptor internalization or CXCR4 signalling.

Exaggerated human monocyte IL-10 concomitant to minimal TNF-alpha induction by heat-shock protein 27 (Hsp27) suggests Hsp27 is primarily an antiinflammatory stimulus.

Unlike more well-studied large heat shock proteins (hsp) that induce both T cell antiinflammatory (IL-10, IL-4) and macrophage proinflammatory (TNF-alpha, IL-15, IL-12) cytokines, hsp27, a small hsp, has been primarily identified as a substrate of mitogen-activated protein kinase-activated protein kinase-2 involved in the p38 signaling pathway and activated during monocyte IL-10 production. Hsp27 can also act as an endogenous protein circulating in the serum of breast cancer patients and a protein whose induction correlates to protection from LPS shock. However, the cytokine-stimulating properties of hsp27 have been unexplored. In this study, exogenous hsp27 is demonstrated for the first time as a potent activator of human monocyte IL-10 production, but only a modest inducer of TNF-alpha. Although exogenous hsp27 stimulation activated all three monocyte mitogen-activated protein kinase pathways (extracellular signal-related kinase (ERK) 1/2, c-Jun N-terminal kinase, and p38), only p38 activation was sustained and required for hsp27 induction of monocyte IL-10, while both ERK 1/2 and p38 activation were required for induction of TNF-alpha when using the p38 inhibitor SB203580 or the ERK inhibitor PD98059. Hsp27's transient activation of the c-Jun N-terminal kinase pathway, which can down-regulate IL-10, may contribute to its potent IL-10 induction. Hsp27's ERK 1/2 activation was also less sustained than activation by stimuli like LPS, possibly contributing to its modest TNF-alpha induction. The failure of either PD98059 or anti-TNF-alpha Ab to substantially inhibit IL-10 induction implied that hsp27 induces IL-10 via activation of p38 signaling independently of TNF-alpha activation and may be predominantly an antiinflammatory monokine stimulus.

Induction of global anergy rather than inhibitory Th2 lymphokines mediates posttrauma T cell immunodepression.

Depressed mitogen-induced IL-2 and IFN-gamma responses after severe mechanical or thermal injury are postulated to result from an expansion of Th2 lymphocytes with concomitant excessive production of IL-4 and/or IL-10. Here, we simultaneously assessed proliferation and Th1 (IFN-gamma) versus Th2 (IL-10, IL-4) lymphokine production in trauma patients' isolated T cells stimulated in a costimulation sufficient, antigen presenting cell independent system (anti CD3 + anti-CD4). T cells with depressed proliferation and IL-2 production simultaneously lost IL-4, IL-10, and IFN-gamma protein and mRNA responses. Exogenous IL-12 addition did not restore IFNgamma responses, but exogenous IL-2 partially restored IL-4, IFN-gamma, and IL-10 production. Although initially partially restored by exogenous IL-2 or stimulation with PMA + ionomycin, patient T cells with persisting anergy progressively lost even these lymphokine and proliferative responses. Development of global T cell anergy was not a result of lost T cell viability or protein synthesis, since it corresponded to predominance of anergic T cells with upregulated expression of CD11b, but downregulated CD28 and CD3 expression. Thus, the subset of posttrauma patients whose isolated T cells become unresponsive experienced progressively worsening global anergy, mediated not by an increased production of Th2 lymphokines, but possibly by T cell incapacity to be activated through TCR triggering or Ca(2+) mobilization.

Relationships between T lymphocyte apoptosis and anergy following trauma.

BACKGROUND: Severely injured trauma patients experience T cell depletion. A subset of these patients also develop T cell unresponsiveness (anergy), as characterized by the failure of their T cells to proliferate or to produce T lymphokines in response to a direct stimulus through the T cell receptor. We hypothesized that T cell apoptosis plays a role in the development of posttrauma T cell depletion and/or T cell anergy by deleting an activated T cell population. We found that moderately increased T cell depletion posttrauma is not innately deleterious or immediately responsible for anergy, but may predispose to later development of T cell anergy, possibly due to a more stringent requirement for activation of the remaining naive T cells. METHODS: A total of 30 blunt trauma and burn patients were assessed twice weekly for the following parameters: (1) clinical outcome expressed as severity of organ dysfunction as measured by the multiple organ dysfunction syndrome score, (2) proliferative response of highly purified T cells to anti-CD3/anti-CD4, (3) level of apoptosis as determined by flow cytometric analysis of propidium iodide-stained monocyte reduced peripheral blood mononuclear cells, either unstimulated or in response to mitogenic challenge or Fas (CD95) stimulation. RESULTS: A wide range of apoptosis levels are seen in the patients' T cells. Apoptosis is increased when all trauma patients' T cells are compared to T cells of normal volunteers. However, at the time a patients' T cells are anergic, there is no increased level of apoptosis. In fact, the point of maximum anergy (lowest proliferative response) correlates to diminished apoptotic response. Increased T cell apoptosis can be stimulated by anti-Fas antibody in trauma patients' responsive T cells but not in maximally anergic T cells. These data suggest that patients' T cell anergy is not an immediate result of apoptotic T cell depletion upon stimulation. However, patients who later develop T cell anergy have increased T cell apoptosis earlier in their clinical course than patients who never experience T cell anergy. CONCLUSIONS: Increased levels of apoptosis are not directly associated with negative trauma patient outcome nor the immediate cause of T cell anergy. However, unusually high levels of apoptosis and development of severe T cell depletion occurring before complete activation and expansion of the posttrauma T cell response may presage anergy and subsequent organ failure.

Maximal T cell IL-13 production requires monocyte or monokine participation.

The T cell-secreted lymphokine interleukin 13 (IL-13) exerts pleiotropic effects on monocytes (Mphi) and B cells. Since accessory cells, like Mphi and B cells, also act in antigen-presenting and lymphokine augmentation of T cells, Mphi and B cells may be able to effect T cell IL-13 production. Purified T cells produced slightly less IL-13 than the lower T cell numbers contained in peripheral blood mononuclear cell population, further suggesting accessory cell augmentation. Addition of 10% B cells [either unstimulated or pokeweed mitogen (PWM)-stimulated] to autologous T cells only moderately augmented T cell IL-13 levels. PWM-stimulated B cell culture supernates had even less augmenting effect on T cell IL-13 levels and unstimulated B cell culture supernates did not augment T cell IL-13 production. In contrast to the moderately augmenting effect of B cells or their stimulated culture supernates, addition of 10% Mphi, either unstimulated or muramyl dipeptide (MDP)+IFN-gamma stimulated, to autologous T cells produced a highly significant increase in T cell IL-13 production. Mphi culture supernates were equally effective in augmenting T cell IL-13 levels, suggesting both that cell-to-cell contact is not critical for Mphi augmentation of T cell IL-13 levels, and that Mphi secreted factors are pivotal. CD64(+) Mphi (or their culture supernates), which are known as poor antigen-presenting cells, also effectively augmented T cell IL-13 production, further supporting the involvement of Mphi secreted factors. Finally, experiments with exogenous addition of recombinant monokines, as well as neutralization experiments with different cytokine antibodies, suggested IL-1beta as a primary cytokine involved in the augmentation of T cell IL-13 levels by accessory cells. However, these experiments also indicated other unidentified Mphi factors as playing a significant role in producing maximal T cell IL-13 production.

Increased monocyte TNF-alpha message stability contributes to trauma patients' increased TNF production.

Post-trauma elevation of tumor necrosis factor alpha (TNF-alpha) appears to be critical in mediating many symptoms of systemic inflammatory response syndrome (SIRS), resulting in late mortality. Although increased monocyte (mphi) TNF-alpha production plays a pivotal role in this TNF-alpha elevation, the molecular mechanisms leading to increased mphi TNF-alpha production have yet to be elucidated. We demonstrate that, although TNF-alpha mRNA levels are increased in all trauma patients' mphi, which produce elevated levels of TNF-alpha protein, in the majority of patients, these increased TNF-alpha mRNA levels are under normal transcriptional and posttranscriptional control. Consequently, the increased TNF-alpha production by these patients' mphi is probably due to preactivation of these mphi by trauma-released mediators. However, a small minority of patients, whose mortality rate was 57%, produce TNF-alpha of primarily the membrane-associated type. The mphi TNF-alpha mRNA accumulation of these patients in response to in vitro stimulation is significantly augmented. All of these patients experienced SIRS. In this subset of patients' mphi, TNF-alpha mRNA stability was aberrantly increased. Such an increase in TNF-alpha mRNA stability could lead to devastatingly prolonged production of TNF-alpha protein. This demonstration of increased TNF-alpha mRNA stability in post-trauma mphi represents a novel correlation of elevated membrane-associated TNF-alpha protein, increased mortality, and a mechanism for this occurrence.

Only a subset of trauma patients with depressed mitogen responses have true T cell dysfunctions.

Many studies have demonstrated depressed mitogenic responses in trauma/burn patients' peripheral blood mononuclear cells (PBMC). However, data attributing the relative contribution of secreted inhibitory factors versus a true T cell dysfunction to these depressed mitogenic responses have been conflicting. We have characterized the T cell dysfunctions in posttrauma mitogen depression by simultaneously assessing patient T cell proliferation in the phytohemagglutinin-stimulated PBMC and in the purified T cell population induced with anti-CD3 + anti-CD4. Patients' samples showed three distinct patterns or progressive phases of T cell responses: (i) normal or elevated T cell proliferation in both the whole PBMC and the isolated T cell population (phase I); (ii) depressed T cell proliferation in the PBMC but normal, or even elevated, proliferation in the isolated T cell population (phase II); and (iii) depressed T cell proliferation in both the PBMC and the isolated T cell population (phase III). Patients whose T cells exhibited only a phase I response experienced no major complications with a positive clinical outcome. Patients whose T cell alterations progressed to phase II experienced infectious episodes and some complications, but all had positive clinical outcomes. In contrast, patients whose T cells progressed to phase III dysfunction had severe clinical complications (multiple organ failure), with a negative clinical outcome (80% mortality). Patients whose T cells had a phase I or phase II response pattern had no true T cell dysfunctions in the absence of monocytes. However, patients whose T cells had a true T cell dysfunction (phase III) response pattern were at high risk for mortality. Thus, a true T cell dysfunction, though occurring in only a minority of trauma patients, is predictive of clinical outcome.

A membrane TNF-alpha/TNFR ratio correlates to MODS score and mortality.

This study hypothesizes that post-trauma elevated membrane-associated tumor necrosis factor-alpha (mTNF) and decreased TNF receptor shedding may be more related to development of multiple organ dysfunction syndrome (MODS) than elevated secreted TNF-alpha. We also address several of the possible reasons for the previous conflicting reports in studies correlating trauma patients sera TNF-alpha levels to their clinical outcome. These are 1) the lack of an objective quantitative score of clinical illness severity, 2) the lack of multiple TNF-alpha measurements in one patient to allow for trend analysis, 3) the lack of analysis of membrane-associated as well as secreted TNF-alpha levels, 4) the lack of concomitant analysis of soluble TNF-alpha receptors which may bind TNF-alpha in the serum, and 5) the possible requirement for more than one dysfunction in monocyte (M phi) TNF-alpha production and regulation to initiate pathology. Here, the MODS score was used to quantitate patients' illness severity over the length of their intensive care unit (ICU) stay. Patients' and normals' monocytes (stimulated and unstimulated) were assessed for production of secreted as well as membrane-associated TNF-alpha (sTNF and mTNF) and for shed p75 TNF-alpha receptor (TNFR) levels. These parameters of M phi TNF-alpha production and regulation were correlated to the MODS score as an indicator of clinical outcome. There was no correlation between sTNF and MODS score (p = .9025). There was a correlation between increased mTNF (p = .057) or decreased TNFR shedding (p = .0021) to increased MODS, but this lacked specificity. However, when the stimulated M phi production of mTNF and TNFR are expressed as the mTNF/TNFR ratio, an increased ratio correlates with high specificity to development of organ failure (p = .0002). These data indicate that a dual deregulation in M phi TNF-alpha production reflects increasing mTNF-alpha levels concomitant to decreased M phi shedding of neutralizing TNFR and correlates with the development of MODS.

17 beta-estradiol induced prostatitis in the rat is an autoimmune disease.

PURPOSE: Studies suggest that alteration in steroid hormone levels may be one of the factors causing nonbacterial prostatitis (NBP) in rats. We hypothesized that hormonally induced prostatitis in the rat may be an autoimmune disease. Studies were carried out to prove this hypothesis. MATERIALS AND METHODS: We injected 17 beta-estradiol (E2; 250 micrograms/kg. subcutaneously) or vehicle into 1-year-old male rats for 30 days, and isolated and cultured the splenocytes in the presence of con-A (Experiment 1). Approximately 10(7) splenocytes were adoptively transferred into young naive syngeneic rats. To find out whether or not the inflammation is mediated by T-lymphocytes, a pure population of T-lymphocytes from E2-treated 3-month-old rats was injected into young naive syngeneic rats (Experiment 2). To rule out the possibility that the inflammation was due to con-A itself, we cross-linked some T-cells with anti-CD3 antibody before adoptive transfer (Experiment 2). RESULTS: The recipients of splenocytes from E2-treated animals presented evidence of inflammation in terms of lymphocytic infiltration and presence of degranulated mast cells. Furthermore, we observed in these animals an increase in histamine-releasing peptide (HRP) levels, an indication of plasma extravasation. The T-cells stimulated by anti-CD3 antibody produced a similar degree of inflammation, thereby ruling out the possibility that the inflammation was due to con-A. The results also indicated that the immune response to antigen(s) is not dependent on the age of the animal but is dependent on a population of CD3+ T-cells. CONCLUSION: Our results demonstrate that hormonal imbalance and autoimmunity in male rats produce the symptoms of nonbacterial prostatitis.

Elevated IL-8 production by trauma patients' monocytes is associated with elevated secretion of TNF alpha.

IL-8 is a recently described chemokine that increases polymorphonuclear neutrophil infiltration and has been implicated in inflammatory pathology. This study assesses monocyte (M phi) interleukin-8 (IL-8) levels in severe trauma patients (injury severity score > 16) who have elevated levels of M phi cell-associated tumor necrosis factor alpha (TNF alpha), a major marker for systemic inflammatory response syndrome after injury. We demonstrate elevated (p = .0007) levels of M phi IL-8 only in those trauma patients who also have increased (p = .0001) M phi-secreted TNF alpha whereas the patients having normal M phi-secreted TNF alpha levels have normal or even decreased M phi IL-8 production. There is no association between M phi IL-8 production and cell-associated TNF alpha levels. M phi induction by Fc gamma RI cross-linking, a common induction pathway in trauma patients' M phi that increases the production of both cell-associated and secreted TNF alpha, can also increase (p = .0022) M phi IL-8 levels. Therefore, post-trauma elevation of M phi IL-8 levels may be associated with increased secreted TNF alpha resulting from, at least in part, Fc gamma RI cross-linking stimulation in vivo.

Altered IL-10 levels in trauma patients' M phi and T lymphocytes.

Trauma results in concomitant immunosuppression and elevated monocyte (M phi) inflammatory cytokine levels. The augmenting or ameliorating effect of IL-10 in septic complications after trauma is controversial. Here, IL-10 levels of trauma patients' and normals' PBMC, isolated M phi, and isolated T cells were assessed and correlated to their PBMC mitogen responses, their T-cell proliferation in an APC independent system, and their M phi production of elevated TNF-alpha levels. Trauma patients with depressed PBMC responses to PHA stimulation also had significantly decreased IL-10 levels in their stimulated PBMC supernates (P = 0.0022) and their MDP-stimulated isolated M phi population (P = 0.0004). However, patients with depressed PHA responses could have either normal or depressed T-cell proliferation in an anti-CD3-, anti-CD4-stimulated system. If APC-independent T-cell proliferation was depressed, induced IL-10 levels were suppressed (P = 0.007). However, if APC-independent T-cell proliferation was normal or elevated, IL-10 levels could be normal or elevated (P = 0.018). Decreased IL-10 levels correlated with depressed mitogen responses and depressed T-cell proliferation. IL-10, therefore, could not be inducing trauma patients' immunosuppression. Patients with elevated M phi TNF-alpha levels had depressed M phi IL-10 levels.

Continued tumor necrosis factor receptor expression by trauma patients' monocytes (Mphi) despite TNF alpha secretion.

In investigating various mechanisms for continued elevated tumor necrosis factor alpha (TNF alpha) production in trauma patients' monocytes (Mphi), we examined TNF receptor (TNFR) levels on the patients' Mphi as a possible altered pathway leading to continued autocrine TNF alpha stimulation. Mphi TNFR synthesis and shedding are both increased as TNF alpha protein production increases. In fatal meningococcal infections, TNFR shedding fails to pace TNF alpha production. Here, isolated normal and trauma patients' Mphi (injury severity score greater than 30), were examined by flow cytometry using phycoerythrin-labeled TNF alpha to detect increased or decreased TNFR expression concomitant to Mphi production of secreted TNF alpha (as measured in the LM bioassay). Immunoaberrant patients (mitogen proliferation depressed) had reduction in detectable TNF alpha binding by their TNFR, while Mphi from immunocompetent (normal mitogen response) trauma patients' Mphi had a TNFR expression intensity comparable to normals' Mphi. Upon in vitro stimulation of TNF alpha (IFN gamma + muramyl dipeptide) normals' and immunocompetent patients' MO TNFR expression is decreased for the entire 18 h period during which secreted TNF alpha is produced, but immunoaberrant trauma patients' Mphi increased their TNFR expression, while concomitantly producing both secreted and cell-associated TNF alpha protein. Patients' Mphi with highly elevated TNF alpha levels are still expressing high levels of TNFR and capable of auto-stimulating TNF alpha production. This elevated TNFR expression could be due to reduced shedding, overproduction of TNFR, or both.

Dibutyryl-cAMP modulation of receptor expression and antigen presentation capacity in monocyte subpopulations.

Monocyte phenotype heterogeneity is often associated with functional differences between the distinguished Mphi subpopulations. We have previously demonstrated that the Mphi subpopulation separated and stimulated by rosetting Mphi via the Type I Fc gamma R (CD64) are poor antigen presenting cells but can be induced to greater production of TNF alpha, IL-6 and PGE2 than the Fc gamma RI- Mphi population. Here we demonstrate that the Fc gamma RI- Mphi represent the major antigen presenting Mphi population and that APC capacity of the FcRI- Mphi can be further increased by elevating intracellular cAMP levels. Treatment of the Fc gamma RI+ Mphi with db cAMP decreases both their expression of CD64 and their capacity to produce TNF alpha to the levels typical of Fc gamma RI- Mphi. Db cAMP treatment of the Fc gamma RI+ Mphi subpopulation, however, cannot augment the antigen presenting capacity of this low APC Mphi subpopulation to the level of that of the Fc gamma RI- Mphi. Basal expression of the Mo3 activation marker was comparable in the FcRI+/FcRI- Mphi subpopulations, but the FcRI+ Mphi were induced by db cAMP treatment to increase their Mo3 expression to higher levels than the FcRI- Mphi. These results suggest that although elevated intracellular cAMP levels can modulate some Fc gamma RI+ Mphi functions to more closely parallel those of the Fc gamma RI- Mphi, this treatment cannot increase the efficiency of the Fc gamma RI+ Mphi subpopulation as an antigen presenting cell.

Differential induction of human monocyte transforming growth factor beta 1 production and its regulation by interleukin 4.

We have previously shown that trauma patients' monocytes which are in vivo activated by multiple injury-induced mediators have elevated transforming growth factor-beta (TGF beta) bioactivity. Interleukin-4 (IL-4), a Th2 and B lymphocyte stimulatory factor, has been shown to inhibit monocyte production of a number of mediators both after lipopolysaccharide stimulation and after trauma-induced stimulation. However, IL-4 inhibitory effects appears to vary, depending on the mixture of inducing stimuli. Here we describe the in vitro IL-4 inhibition of human monocyte TGF beta bioactivity using several stimulation induction protocols: muramyl dipeptide stimulation alone, or after Fc gamma RI (CD64) cross-linking induction, interferon-gamma (IFN gamma) priming, or trauma-generated in vivo mediator induction. IL-4 suppressed both muramyl dipeptide-induced TGF beta bioactivity and TGF beta mRNA in a dose-dependent fashion and was most effective when IL-4 was administered at initiation of normal monocyte stimulation. Muramyl dipeptide (MDP)-induced increases in trauma patients' monocyte TGF beta bioactivity were also inhibited by high doses of IL-4 (25 ng/ml). Fc gamma RI cross-linking increased MDP-induced normal monocyte TGF beta bioactivity, but this increase could be consistently inhibited only by very high IL-4 concentrations (50 ng/ml). IL-4 did not consistently downregulate MDP-induced TGF beta bioactivity in IFN gamma-primed monocytes. IL-4 can suppress monocyte TGF beta production, as well as other monocyte mediators, but its efficiency depends on the stimuli combination present in the microenvironment.

Elevated monocyte interleukin-6 (IL-6) production in immunosppressed trauma patients. II. Downregulation by IL-4.

Aberrant monocyte mediator production is pivotal in the development of posttrauma immunosuppression. We have previously shown that immunodepressed trauma patients' monocytes produce elevated interleukin-6, suggesting their in vivo preactivation. This study confirms that preactivated patients' Mø produce greater levels of IL-6 than normals' Mø to the same in the in vitro Fc gamma RI stimulation. We also demonstrate the capacity of interleukin-4 to downregulate the elevated interleukin-6 production of trauma patients' in vivo preactivated monocytes. Monocyte interleukin-6 downregulation by interleukin-4 is dose dependent and occurs whether Fc gamma RI cross-linking, muramyl dipeptide, indomethacin plus muramyl dipeptide, or interferon-gamma plus muramyl dipeptide is the interleukin-6 inducing stimulus. Furthermore, interleukin-4-dependent downregulation of monocyte interleukin-6 expression is confirmed at both the supernatant and the mRNA levels. Simultaneous downregulation of posttrauma elevated monokines implies a possible therapeutic benefit of interleukin-4 for trauma patients.

Elevated monocyte interleukin-6 (IL-6) production in immunosuppressed trauma patients. I. Role of Fc gamma RI cross-linking stimulation.

This study demonstrates that immunodepressed trauma patients' monocytes produce elevated interleukin-6 to adherence, bacterial, and cytokine stimulation compared to immunocompetent trauma patients' or normals' monocytes, suggesting their in vivo preactivation possibly mediated by the hyperimmunoglobulinemia which characterizes these patients. Furthermore, stimulation of monocytes through cross-linking their Fc gamma RI induces and augments interleukin-6 (IL-6) production to subsequent stimulation both in trauma patients' (P less than 0.001) and in normals' (P less than 0.001) monocytes. As we reported earlier, immunodepressed trauma patients have an increased proportion of Fc gamma RI-bearing monocytes in their total monocyte population and here we show that those Fc gamma RI+ monocytes produce significantly elevated interleukin-6, suggesting a relationship between elevated monocyte interleukin-6 production and Fc gamma RI triggering. Interleukin-6 induction by FcRI stimulation is not mediated solely by FcRI-induced M phi tumor necrosis factor alpha, IL-1 alpha, or IL-1 beta production and is independent of M phi prostaglandin E2 levels. Therefore, FcRI stimulation-induced elevated M phi IL-6 might contribute to the increased immunoglobulin levels posttrauma.

Role of elevated monocyte transforming growth factor beta (TGF beta) production in posttrauma immunosuppression.

We previously reported that increased production of prostaglandin E2 by monocytes is a pivotal mechanism in posttrauma immunopathology. Here we characterize monocyte levels of transforming growth factor beta and examine the effects of elevated transforming growth factor beta on prostaglandin E2 release by patients' monocytes. Trauma patients' and normals' monocyte supernates (+/- stimulation with muramyl dipeptide) were acid treated and assayed for transforming growth factor beta using the mink lung-cell bioassay. Alternatively, human transforming growth factor beta was added to patients' and normals' monocytes and prostaglandin E2 production assayed. Significantly elevated transforming growth factor beta levels (median = 181.7 pmol/10(6) monocytes) were detected in immunosuppressed patients' monocytes but not immunocompetent trauma patients' (median = 32.0 pM) or normals' (median = 20.4 pM) monocytes. Adding transforming growth factor beta to monocytes resulted in a significant elevation of prostaglandin E2 levels. Elevated monocyte transforming growth factor beta levels in trauma patients could be both suppressing T-lymphocyte functions and maintaining elevated monocyte prostaglandin E2 synthesis.

Aberrations in post-trauma monocyte (MO) subpopulation: role in septic shock syndrome.

Appearance of increased proportions of monocytes bearing the 72kd(FcRI) receptor for IgG correlated to aberrant monocyte (MO) functions, depressed immune functions, and poor clinical outcome. The trauma patients' FcRI+ MO subpopulation produced the majority of their elevated IL-6, TNF alpha, TGF beta, and PGE2. IgG stimulation of patients' MO through FcRI not only stimulated TNF alpha, IL-6, and PGE2 levels, but also greatly augmented the levels of these monokines produced after subsequent bacterial challenge. Post-trauma increased IL-6 levels can lead to polyclonal B-cell activation and high levels of circulating, nonspecific IgG as seen in trauma patients. This nonspecific IgG triggers the FcRI on the increased numbers of FcRI+ MO leading to ever-increasing monokine levels. IL-4 was found to downregulate patients' FcRI+ MO production of mediators. The cycle of altered cytokine levels, increased FcRI+ MO numbers, elevated IgG, and augmented triggering of FcRI+ MO may be broken by addition of IL-4.