Respuesta inflamatoria sistémica: definiciones, marcadores inflamatorios y posibilidades terapéuticas / Systemic inflammatory response: definitions, inflammatory markers and therapeutic possibilities

Introducción. Se analizan las definiciones y las teorías fisiopatológicas que se han elaborado para explicar la evolución del síndrome inflamatorio hacia la disfunción multisistémica, analizando el valor predictivo de los diferentes mediadores y de los cambios metabólicos. Tras revisar las características del síndrome inflamatorio se recogen los diferentes intentos terapéuticos para modular el SIRS. Material. Se ha revisado la bibliografía recogida en Medline, fundamentalmente estudios clínicos realizados en pacientes críticos. Resumen. Se describen tres síndromes (SIRS, CARS y MARS) que pueden configurar la respuesta inflamatoria. La evolución hacia la disfunción multisistémica es explicada por diversas teorías, pero queda por estudiar los mecanismos que permiten la modulación y supresión de la respuesta inflamatoria. A pesar de su importancia fisiopatológica, las citocinas de inicio no son buenos marcadores pronósticos. Los marcadores de fase aguda, así como los cambios en el metabolismo lipídico y del hierro, muestran una mejor correlación con la evolución. Tras comentar que la respuesta inflamatoria no es proporcional, estructural ni universal, se revisan los diversos intentos terapéuticos que pretenden antagonizar dicha respuesta. Se comentan las tres líneas que deben regir para las investigaciones futuras (AU)

Acquisition of selectin binding and peripheral homing properties by CD4(+) and CD8(+) T cells.

Different T cell subsets exhibit distinct capacities to migrate into peripheral sites of inflammation, and this may in part reflect differential expression of homing receptors and chemokine receptors. Using an adoptive transfer approach, we examined the ability of functionally distinct subsets of T cells to home to a peripheral inflammatory site. The data directly demonstrate the inability of naive T cells and the ability of effector cells to home to inflamed peritoneum. Furthermore, interleukin (IL)-12 directs the differentiation of either CD4(+) or CD8(+) T cells into effector populations that expresses functional E- and P-selectin ligand and that are preferentially recruited into the inflamed peritoneum compared with T cells differentiated in the presence of IL-4. Recruitment can be blocked by anti-E- and -P-selectin antibodies. The presence of antigen in the peritoneum promotes local proliferation of recruited T cells, and significantly amplifies the Th1 polarization of the lymphocytic infiltrate. Preferential recruitment of Th1 cells into the peritoneum is also seen when cytokine response gene 2 (CRG-2)/interferon gamma-inducible protein 10 (IP-10) is used as the sole inflammatory stimulus. We have also found that P-selectin binds only to antigen-specific T cells in draining lymph nodes after immunization, implying that both antigen- and cytokine-mediated signals are required for expression of functional selectin-ligand.

Importance of E-selectin for firm leukocyte adhesion in vivo.

Leukocyte adhesion under flow is preferentially mediated by the selectins. In this study we used intravital microscopy to investigate whether E-selectin may promote firm leukocyte adhesion in vivo. E-Selectin is expressed by endothelial cells activated with tumor necrosis factor-alpha (TNF-alpha) and causes slow leukocyte rolling. Microinjection of formyl-methionyl-leucyl-phenylalanine (fMLP) or macrophage inflammatory protein-2 (MIP-2) next to a venule of the TNF-alpha-treated mouse cremaster muscle significantly increased the number of adherent leukocytes. In gene-targeted mice homozygous for a null mutation in the E-selectin gene or in wild-type mice treated with an E-selectin monoclonal antibody (mAb), this response was significantly attenuated (by >80%). No such defect was seen in intercellular adhesion molecule-1 (ICAM-1)-deficient mice. E-Selectin-null mice showed more rapid leukocyte rolling than wild-type or ICAM-1-deficient mice, resulting in significantly shortened leukocyte transit times through venules. Topical application of fMLP onto the whole cremaster muscle generated the same number of adherent leukocytes in wild-type and E-selectin-deficient mice. We conclude that slow leukocyte rolling through E-selectin results in long transit times, which are essential for efficient leukocyte adhesion in response to a local chemotactic stimulus.

Possible participation of macrophage inflammatory protein 2 in neutrophil infiltration in allergic inflammation in rats.

Recombinant rat macrophage inflammatory protein 2 (MIP-2) was prepared from E. coli transfected with a glutathione-S-transferase (GST)-MIP-2 fusion protein expression vector. A polyclonal antibody to rat MIP-2 was then obtained from rabbits by immunization with recombinant rat MIP-2. Using the polyclonal antibody which selectively suppressed neutrophil chemotactic activity of MIP-2, the role of MIP-2 in neutrophil infiltration in allergic inflammation in rats was studied. In an air pouch-type allergic inflammation model in rats, neutrophil infiltration into the pouch fluid increased with time after antigen challenge. Neutrophil chemotactic activity in the pouch fluid collected 8 h after antigen challenge was diminished by anti-MIP-2 antibody. In addition, when leukocytes that had infiltrated into the pouch fluid collected 4 h after antigen challenge were incubated, neutrophil chemotactic activity in the conditioned medium increased time-dependently, and the activity was neutralized by anti-MIP-2 antibody. Furthermore, when anti-MIP-2 antibody was injected into the pouch 6 h after antigen challenge, neutrophil infiltration into the pouch fluid during the next 2 h was suppressed. These findings indicate that MIP-2 plays an important role in neutrophil infiltration in rat allergic inflammation.

Intra-alveolar macrophage-inflammatory peptide 2 induces rapid neutrophil localization in the lung.

Endotoxin-induced lung injury is characterized by neutrophil infiltration of the lungs. The various mechanisms which mediate movement of neutrophils from vascular space to lung interstitium and alveoli remain unclear. Macrophage-inflammatory protein 2 (MIP-2) is a potent chemoattractant for neutrophils and may play a significant role in recruiting neutrophils in acute lung injury in rats. Experiments were performed in male Sprague Dawley rats to: (1) evaluate the kinetics of neutrophil influx in the lung following intraperitoneal administration of Salmonella enteritidis lipopolysaccharide (LPS); (2) determine the expression of transcripts for chemokines and adhesion molecules in the lung following intraperitoneal LPS; and (3) elucidate the effects of intra-alveolar instillation of recombinant rat MIP-2 on neutrophil influx into the lung. Intraperitoneal LPS resulted in an increase in neutrophil sequestration in the lung capillaries of rats as early as 45 min following administration, and there was a parallel increase in lung myeloperoxidase activity. There were also major increases in mRNA in whole-lung homogenates of LPS-treated rats for chemokines MIP-2 and KC (cytokine-induced neutrophil chemoattractant) and adhesion molecules P- and E-selectin at 1 and 2 h following LPS. When recombinant rat MIP-2 was instilled into the alveolar space of rats through a catheter wedged into a bronchus, there was profound neutrophil localization both in the vascular and alveolar space which significantly differed (P < 0.05) from the contralateral lungs of the same animals, and lungs of control animals instilled with control buffer. These observations reveal that MIP-2 is a potent chemoattractant in rat lungs, and suggest that chemoattractants locally released in alveoli can recruit neutrophils to those alveoli. This suggests that alveolar macrophages may play an important role in neutrophil sequestration in sepsis and other inflammatory lung diseases which produce a neutrophilic alveolitis.

Chemokines and T lymphocyte activation: II. Facilitation of human T cell trafficking in severe combined immunodeficiency mice.

Previous studies from this laboratory have demonstrated that the chemokines RANTES (recombinant human regulated upon activation, normally T cell expressed and presumably secreted), macrophage chemotactic peptide-1, recombinant human macrophage inflammatory protein-1 alpha (rhMIP-1 alpha) IL-8, and IP-10 are capable of inducing human T cell infiltration into the injection site of severe combined immunodeficiency (SCID) mice reconstituted with human PBL. However, the ability of these chemokines to facilitate T cell homing into various lymphoid tissues has not been examined. Initial studies focused on the ability of rhMIP-1 beta to induce human T cell infiltration into injection sites in human PBL-SCID mice. SCID mice received s.c. injections of rhMIP-1 beta or PBS (1 microgram/injection) in the hindflank for 4 h or sequential injections for 3 days. Biopsies of the MIP-1 beta injection site revealed the presence of significant mononuclear cell accumulation 72 h after injection. Immunohistologic evaluation determined that significant numbers of human CD3+ T cells were recruited in response to MIP-1 beta injections, and this infiltration could be specifically blocked by co-administration of anti-MIP-1 beta antiserum. We subsequently examined these chemokine-injected mice for the effect of trafficking of human T cells to peripheral lymphoid organs. Flow cytometric analysis of the thymus in human PBL-SCID mice revealed that treatment with rhMIP-1 beta or rhRANTES, but not platelet factor-4, resulted in improved thymic homing of the human T cells after 72 h. This trafficking effect was shown to be direct, as pretreatment of the human T cells with the chemokines in vitro also improved peripheral lymphoid trafficking of the human cells. In addition, co-injection of rhMIP-1 beta with anti-1 beta antiserum abrogated the increase in T cell homing to the thymus. These data demonstrate that MIP-1 beta and RANTES directly augment human T cell trafficking to peripheral murine lymphoid tissues. Chemokines may, therefore, under either isogeneic or xenogeneic conditions, play a role in normal lymphocyte recirculation and homing, and may be of potential clinical use in promoting immune cell trafficking and function.

Fever induced in rats by intrahypothalamic macrophage inflammatory protein (MIP)-1 beta: role of protein synthesis.

The effect of macrophage inflammatory protein-1 beta (MIP-1 beta) on body temperature, following its injection into the anterior hypothalamic pre-optic area (AH/POA), was examined by a radiotelemetry system in the freely moving rat. The purpose of this study was to examine the action of an inhibitor of protein synthesis, anisomycin, on the pyrexia which follows intrahypothalamic injection of MIP-1 beta. The micro-injection of 10 to 20 pg MIP-1 beta into the AH/POA induced a dose-dependent monophasic increase in body temperature, whereas a higher dose of 25 pg of the cytokine caused a biphasic febrile response. When MIP-1 beta was heated at 70 degrees C for 30 min prior to its administration, the pyrogenic response was abolished. Pretreatment of the micro-injection site in the AH/POA with 10 micrograms anisomycin did not alter the febrile response to 25 pg MIP-1 beta given at the same site in the AH/POA. When 10 mg/kg anisomycin was administered subcutaneously, the febrile response to 25 pg MIP-1 beta injected in the AH/POA was significantly suppressed. The present results suggest that fever caused by MIP-1 beta within the cells of the AH/POA may not require the synthesis of a new protein factor; however, the de novo synthesis of a protein outside of the AH/POA presumably plays a functional role, at least in part, in the intense fever produced by this cytokine in the hypothalamus.

Fever and feeding in the rat: actions of intrahypothalamic interleukin-6 compared to macrophage inflammatory protein-1 beta (MIP-1 beta).

The chemokines, macrophage inflammatory protein-1 (MIP-1) and its subunit MIP-1 beta, induce an intense fever in the rat when they are injected directly into the anterior hypothalamic, pre-optic area (AH/POA), a region containing thermosensitive neurons. The purpose of this study was to compare the central action on body temperature (Tb) of MIP-1 beta with that of interleukin-6 (IL-6), which also has been implicated in the cerebral mechanism underlying the pathogenesis of fever. Following the stereotaxic implantation in the AH/POA of guide cannulae for repeated micro-injections, radio transmitters which monitor Tb continuously were inserted intraperitoneally in each of 15 male Sprague-Dawley rats. Each micro-injection was made in a site in the AH/POA in a volume of 1.0 microliter of pyrogen-free artificial CSF, recombinant murine MIP-1 beta, or recombinant human IL-6. MIP-1 beta in a dose of 25 pg evoked an intense fever characterized by a short latency, a mean maximum rise in Tb of 2.4 +/- 0.21 degrees C reached by 3.7 +/- 0.42 hr, and a duration exceeding 6.5 hr. Injected into homologous sites in the AH/POA, IL-6 induced a dose dependent fever of similar latency and a mean maximal increase in Tb of 1.2 +/- 0.25 degrees C, 1.8 +/- 0.15 degrees C, and 2.1 +/- 0.22 degrees C and duration of 6.2 +/- 1.28 hr, 6.7 +/- 0.49 hr, and 6.8 +/- 0.65 hr when given in doses of 25, 50, and 100 ng, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemokine-induced fever: intracerebroventricular actions of MIP-1 and MIP-1 alpha in rats.

The central pyrogenic actions in the rat of doublet macrophage inflammatory protein-1 (MIP-1) and MIP-1 alpha were determined by their intracerebroventricular infusion. Doses of 560 pg and 11.2 ng of MIP-1 or 10.0 ng MIP-1 alpha infused into the third cerebral ventricle induced a long lasting fever. However, MIP-1 alpha was much less potent than MIP-1 in terms of intensity and longer latency. Overall, these cytokines are pyrogenic when acting on the walls of the third ventricle; however, a dose 10 times greater than that injected directly into the anterior hypothalamus is required to evoke fever, as based on earlier experiments. Finally, circulating MIP-1 could act centrally by its entry through the choroid plexus into the ventricular system of the brain.

Chemokines/intercrines and central regulation of feeding.

Chemokines/intercrines are structurally and functionally related cytokines that induce specific actions on the immune system and are released in response to infection, inflammation, and trauma. These pathological processes are frequently accompanied with food intake suppression. In the present study, the action of chemokines/intercrines on the regulation of feeding was investigated using the intracerebroventricular microinfusion of chemokine/intercrine-alpha subfamily members [interleukin-8 (IL-8); growth-related cytokine/melanoma growth-stimulating activity (GRO-alpha/MGSA); platelet factor-4 (PF-4); beta-thromboglobulin (beta-TG); and interferon-inducible protein-10 (IP-10)] and beta-subfamily members [monocyte chemotactic protein-1/monocyte chemotactic and activating factor (MCP-1/MCAF); regulated upon activation normal T-cell expressed and presumably secreted (RANTES); macrophage inflammatory protein-1 alpha (MIP-1 alpha); and macrophage inflammatory protein-1 beta (MIP-1 beta)]. The doses administered were 1.0, 20, and 100 ng/rat of the chemokine/intercrine. The intracerebroventricular administration of three members of the alpha-subfamily (IL-8, PF-4, and IP-10) and two members of the beta-subfamily (MCP-1/MCAF and RANTES) decreased the short-term (2-h) food intake. These effective chemokines/intercrines, however, were significantly less potent than IL-1 beta in decreasing feeding. The results support the hypothesis that only a subset of immunomodulators released during pathological processes may participate in the regulation of feeding with different potencies.

Myelosuppressive effects in vivo with very low dosages of monomeric recombinant murine macrophage inflammatory protein-1 alpha.

Macrophage inflammatory protein (MIP)-1 alpha has myelosuppressive/myeloprotective effects in vivo in mice. We recently reported that > 99.7% of recombinant murine (rm) MIP-1 alpha polymerizes rapidly at relatively high concentrations in physiological salt solution, and it is the monomeric form of MIP-1 alpha that is active in vitro as a myelosuppressive factor. Polymerized MIP-1 alpha is inactive in this effect and does not block the myelosuppressive action of monomeric MIP-1 alpha. MIP-1 alpha could be maintained in monomeric form in physiological saline if diluted to low concentrations. This led us to reevaluate the actual amounts of MIP-1 alpha necessary for myelosuppression in vivo. C3H/HeJ mice were injected intravenously (i.v.) with monomeric rmMIP-1 alpha or control diluent and effects were evaluated on progenitor cells--multipotent colony-forming units (CFU-GEMM), burst-forming units-erythroid (BFU-E), and colony-forming units-granulocyte/macrophage (CFU-GM)--as described in previous studies in which MIP-1 alpha concentrations were used that we now know to have been mainly in polymerized form. Monomeric MIP-1 alpha rapidly decreased cycling rates and absolute numbers of myeloid progenitor cells in marrow and spleen. These effects, which occurred with about 1000-fold less MIP-1 alpha than we previously reported, were dose-dependent, time-related, and reversible. Suppressive effects were noted within 3 hours for cell cycling and within 24 hours for absolute numbers of progenitor cells in marrow and spleen and were lost by 48 hours. Decreased circulating neutrophils were noted at 48 hours. Column-separated polymerized rmMIP-1 alpha was inactive in vivo. These results demonstrate the potency of low doses of monomeric MIP-1 alpha in vivo. Since clinical administration of large amounts of an agent that is mainly in an inactive form may result in severe pharmacological side effects, the information presented here is of relevance for potential clinical trials using MIP-1 alpha as a myelosuppressive/myeloprotective agent.

Fever evoked by macrophage inflammatory protein-1 (MIP-1) injected into preoptic or ventral septal area of rats depends on intermediary protein synthesis.

Macrophage inflammatory protein-1 (MIP-1), a novel cytokine composed of alpha/beta subunits, is released from macrophages during infection. MIP-1 injected intravenously in the rabbit or into the anterior hypothalamic, preoptic area (AH/POA) of the rat causes an intense fever, which is not blocked by prostaglandin synthesis inhibitors, ibuprofin or indomethacin, respectively. The purpose of this study was to determine the role of de novo protein synthesis on the fever evoked by MIP-1 applied to thermosensitive cells of the AH/POA. Guide cannulae were implanted bilaterally above the AH/POA or ventral septal area (VSA) and medially above the third cerebral ventricle in each of 11 male Sprague-Dawley rats. Following postoperative recovery, body temperature (Tb) was monitored by a colonic thermistor probe. The bilateral microinjection of MIP-1 in a dose of 14 pg per 0.5 microliters into the AH/POA caused a biphasic elevation in Tb to 0.9 +/- 0.2 degrees C within 1.0 h, which reached 1.5 +/- 0.2 degrees C within 3.0 h, and persisted for over 6.0 h. An identical injection of MIP-1 into the VSA increased Tb biphasically to 0.1 +/- 0.1 degrees C within 1.0 h and to 0.8 +/- 0.3 degrees C within 3.0 h. The infusion into the third ventricle of 80 micrograms/10 microliters of the inhibitor of protein synthesis, anisomycin, either 10 or 30 min before the microinjection of MIP-1 into the AH/POA, attenuated significantly the rise in Tb for 1.0 to 3.0 h or 2.5 to 3.0 h, respectively. These results coincide with the earlier finding that anisomycin inhibits both endotoxin- and IL-1 beta-induced fevers.(ABSTRACT TRUNCATED AT 250 WORDS)

Action of cyclosporine on fever induced in rats by intrahypothalamic injection of macrophage inflammatory protein-1 (MIP-1).

In order to examine the central mechanism of pyrexic action of macrophage inflammatory protein-1 (MIP-1), guide cannulae for injections were implanted stereotaxically just above the anterior hypothalamic, pre-optic area of the rat. Following post-operative recovery, the body temperature (Tb) of each rat was monitored by a colonic thermistor probe over a test interval of 4 hr. Injected in a 0.5 microliter volume into the anterior hypothalamic pre-optic area, MIP-1, in a dose of 5.6 or 28 pg, evoked an intense fever with a latency of 15-30 min. Pretreatment of the anterior hypothalamic pre-optic area with 1.0 microgram cyclosporine A (CsA), delivered in a volume of 0.5 microliter, delayed the onset of the fever induced by 5.6 pg MIP-1, injected at the same site. Similar injections of CsA also attenuated significantly the magnitude of the fever, following either the 5.6 or 28 pg dose of MIP-1. As a systemic control, 15 mg/kg CsA was administered intraperitoneally, 2.0 hr before the injection of MIP-1 in the anterior hypothalamic pre-optic area. By this route, CsA also delayed the rise in temperature but the fever induced by 5.6 pg MIP-1 reached the same magnitude as that after MIP-1 alone. Conversely, intraperitoneal administration of CsA did not antagonize the pyrexic response evoked by 28 pg MIP-1, injected into the anterior hypothalamic pre-optic area, but rather enhanced the fever.(ABSTRACT TRUNCATED AT 250 WORDS)

Fever induced by macrophage inflammatory protein-1 (MIP-1) in rats: hypothalamic sites of action.

The purpose of this study was to clarify the central site of action as well as functional characteristics of the febrile response of the cytokine, macrophage inflammatory protein-1 (MIP-1). Guide cannulae for microinjection were implanted stereotaxically in the rat just above the pyrogen and thermosensitive area of the anterior hypothalamic, preoptic area (AH/POA). Following postoperative recovery, the body temperature of each rat (Tbo) was monitored during an experiment by a colonic thermistor probe at 0.5-1.0-h intervals. When MIP-1 was microinjected in a 0.5-microliter volume into the AH/POA in one of eight concentrations ranging from 0.0028 nanograms (ng) to 9.0 ng, an intense monophasic or biphasic fever was evoked. The MIP-1-induced increase in the Tbo of the rat was characterized by its short latency of 15 to 30 min and an inverse dose-response curve. Measures of mean latency and maximal rise in Tbo following MIP-1 confirmed the potency of this dose. Although the dose of 0.028 ng produced a fever of over 2.0 degrees C with a latency of only 15 min or less, the hyperthermic response became less intense as the dose of MIP-1 was increased. An anatomical mapping of sites of microinjection which reacted to MIP-1 in mediating fever revealed that the medial portion of the POA of the rat just rostral to the border of the AH was the region of maximum sensitivity to the cytokine.(ABSTRACT TRUNCATED AT 250 WORDS)