Complement component C3-derived neutrophil chemotactic factors purified from exudate of rat carrageenin-induced inflammation

Technical Advance: Changes in neutrophil migration patterns upon contact with platelets in a microfluidic assay

Neutrophils are traditionally regarded as the "first responders" of the immune system. However, recent observations revealed that platelets often respond earlier to recruit and activate neutrophils within sites of injury and inflammation. Currently, platelet-neutrophil interactions are studied by intravital microscopy. Although such studies provide exceptional, physiologic in vivo data, they are also laborious and have low throughput. To accelerate platelet-neutrophil interaction studies, we have developed and optimized an ex vivo microfluidic platform with which the interactions between platelets and moving neutrophils are measured at single-cell level in precise conditions and with high throughput. With the use of this new assay, we have evaluated changes in neutrophil motility upon direct contact with platelets. Motility changes include longer distances traveled, frequent changes in direction, and faster neutrophil velocities compared with a standard motility response to chemoattractant fMLP. We also found that the neutrophil-platelet direct interactions are transient and mediated by CD62P-CD162 interactions, localized predominantly at the uropod of moving neutrophils. This "crawling," oscillatory neutrophil behavior upon platelet contact is consistent with previous in vivo studies and validates the use of this new test for the exploration of this interactive relationship.

Unexpected Inflammatory Effects of Intravaginal Gels (Universal Placebo Gel and Nonoxynol-9) on the Upper Female Reproductive Tract: A Randomized Crossover Study

Intravaginal anti-HIV microbicides could provide women with a self-controlled means for HIV prevention, but results from clinical trials have been largely disappointing. We postulated that unrecognized effects of intravaginal gels on the upper female reproductive tract might contribute to the lower-than-expected efficacy of HIV microbicides. Our objective was to study the effects of intravaginal gels on the immune microenvironment of the cervix and uterus. In this randomized crossover study, 27 healthy female volunteers used a nightly application of intravaginal nonoxynol-9 (N9) gel as a "failed" microbicide or the universal placebo gel (UPG) as a "safe" gel (intervention cycles), or nothing (control cycle) from the end of menses to the mid-luteal phase. At a specific time-point following ovulation, all participants underwent sample collection for measurements of T-cell phenotypes, gene expression, and cytokine/chemokine protein concentrations from 3 anatomic sites above the vagina: the cervical transformation zone, the endocervix and the endometrium. We used hierarchical statistical models to estimate mean (95% CI) intervention effects, for N9 and UPG relative to control. Exposure to N9 gel and UPG generated a common "harm signal" that included transcriptional up-regulation of inflammatory genes chemokine (C-C motif) ligand 20 (macrophage inflammatory factor-3alpha) and interleukin 8 in the cervix, decreased protein concentrations of secretory leukocyte protease inhibitor, and transcriptional up-regulation of inflammatory mediators glycodelin-A and osteopontin in the endometrium. These results need to be replicated with a larger sample, but underscore the need to consider the effects of microbicide agents and gel excipients on the upper female reproductive tract in studies of vaginal microbicides.

Proteomic profiling of heterotopic heart-transplanted rats using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry: potential biomarkers and drug targets

OBJECTIVE

Methotrexate and rapamycin demonstrate an additive effect in prolonging cardiac allograft survival in a major histocompatibility complex mismatched rat model. The present study aimed to identify functional proteins involved in the allograft-protective effects of these two agents and reveal potential diagnostic markers for treating rejection.

METHODS

Serum samples from heterotopic heart-transplanted LEW(RT-1(1)) rats (either without immunosuppressive treatment or treated with methotrexate alone, rapamycin alone, or methotrexate and rapamycin combined) were analysed by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry. Protein profiles obtained using a weak cation exchange ProteinChip® CM-10 array were then analysed using ProteinChip® Software.

RESULTS

Of 28 rejection-related proteins identified, isoelectric point and mass information from two potential candidate proteins matched information from the UniProtKB/Swiss-prot database, suggesting them to be complement component C3f fragment and complement component 4A (C4A, anaphylatoxin).

CONCLUSIONS

Proteomic analysis revealed 28 proteins as potential diagnostic markers of tissue rejection. Of these, 11 proteins may represent targets relating to the additive effects of methotrexate and rapamycin. Two protein peaks, with mass-to-charge ratios of 1950 Da and 8577 Da, may have potential for use in post-transplant diagnosis of rejection.

Dysferlin-deficient muscular dystrophy and innate immune activation

Cells encounter many physical, chemical and biological stresses that perturb plasma membrane integrity, warranting an immediate membrane repair response to regain cell homeostasis. Failure to respond properly to such perturbation leads to individual cell death, which may also produce systemic influence by triggering sterile immunological responses. In this review, we discuss recent progress on understanding the mechanisms underlying muscle cell membrane repair and the potential mediators of innate immune activation when the membrane repair system is defective, specifically focusing on pathology associated with dysferlin deficiency.

Identification of C3a and N-truncated C3a as vascular permeability-enhancing factors from the exudate of chronic phase of carrageenan-induced inflammation in rats

Two basic proteins enhancing vascular permeability have been purified from the exudate of the chronic phase of carrageenan-induced inflammation in rats. One major and one minor peak on reversed-phase HPLC showed molecular masses of 9.3 kDa and 7.6 kDa, respectively, on sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions. NH2-terminal amino acid sequencing analysis of the purified proteins revealed that the major peak is identical to C3a, while the main sequence of the minor peak is identical to NH2-terminal 11 amino acids truncated C3a. In addition, plasmin was able to cleave C3a into the N-truncated C3a. Intradermal injection of both purified C3a and N-truncated C3a into rat skin enhanced vascular permeability, and the increased permeability was suppressed by the pretreatment with cyproheptadine. Our results suggest that the purified C3a and N-truncated C3a have the characteristics of anaphylatoxins and may contribute to exudation in the chronic phase of carrageenan-induced inflammation in rats.

Corticotropin-releasing hormone regulates IL-6 expression during inflammation

Stimulation of the hypothalamic-pituitary-adrenal (HPA) axis by proinflammatory cytokines results in increased release of glucocorticoid that restrains further development of the inflammatory process. IL-6 has been suggested to stimulate the HPA axis during immune activation independent of the input of hypothalamic corticotropin-releasing hormone (CRH). We used the corticotropin-releasing hormone-deficient (Crh(-/-)) mouse to elucidate the effect of CRH deficiency on IL-6 expression and IL-6-induced HPA axis activation during turpentine-induced inflammation. We demonstrate that during inflammation CRH is required for a normal adrenocorticotropin hormone (ACTH) increase but not for adrenal corticosterone rise. The paradoxical increase of plasma IL-6 associated with CRH deficiency suggests that IL-6 release during inflammation is CRH-dependent. We also demonstrate that adrenal IL-6 expression is CRH-dependent, as its basal and inflammation-induced expression is blocked by CRH deficiency. Our findings suggest that during inflammation, IL-6 most likely compensates for the effects of CRH deficiency on food intake. Finally, we confirm that the HPA axis response is defective in Crh(-/-)/IL-6(-/-) mice. These findings, along with the regulation of IL-6 by CRH, support the importance of the interaction between the immune system and the HPA axis in the pathophysiology of inflammatory diseases.

Corticotropin-releasing hormone deficiency unmasks the proinflammatory effect of epinephrine

Traditionally, the adrenal gland has been considered an important endocrine component of the pathway to inhibit acute inflammation via hypothalamic corticotropin-releasing hormone (CRH)-mediated secretion of glucocorticoid. Immunoreactive CRH found in inflamed tissues is a potent proinflammatory factor. Using genetic and pharmacological models of CRH deficiency, we now show that CRH deficiency unmasks a major proinflammatory effect of epinephrine secreted from the adrenal medulla. Together, epinephrine and peripheral CRH stimulate inflammation, and glucocorticoid acts as a counterbalancing force in this regard. Our findings suggest that stimulation of the acute inflammatory response should be included with the other "fight-or-flight" actions of epinephrine.

Biological activities of C3 beta c, a novel neutrophil chemoattractant derived from the beta-chain of rat complement C3

Biological activities of C3 beta c, which is a C-terminal fragment of the beta-chain of rat complement C3, have been studied by in vivo and in vitro experiments. C3 beta c was purified as a novel neutrophil chemoattractant from the exudate of the chronic phase of rat carrageenin-induced inflammation. The purified C3 beta c induced neutrophil chemotaxis in vivo when C3 beta c was injected into the preformed air-pouch on the back of rats. C3 beta c transiently increased the intracellular free Ca2+ concentration of neutrophils and enhanced the adhesion of neutrophils to fibrinogen in vitro, suggesting that C3 beta c has the ability to express an adhesion molecule of rat neutrophils. In addition, C3 beta c at low concentrations (10(-10)-10(-11) M) stimulated rat macrophages to produce cytokine-induced neutrophil chemoattractant-2, a member of the interleukin-8 family. Furthermore, C3 beta c enhanced vascular permeability in vivo, which is suppressed by cyproheptadine, suggesting that C3 beta c may have the characteristics of an anaphylatoxin. Our results suggest that C3 beta c contributes to oedema formation and neutrophil accumulation at inflammatory sites in rats.

Inhibition of human complement by beta-glycyrrhetinic acid

Licorice, the root extract of Glycyrrhiza glabra I., is used as a medicine for various diseases. Anti-inflammatory as well as anti-allergic activities have been attributed to one of its main constituents, glycyrrhizin. These activities are mainly ascribed to the action of the aglycone, beta-glycyrrhetinic acid. beta-Glycyrrhetinic acid has a steroid-like structure and is believed to have immunomodulatory properties. To determine whether interference with complement functions may contribute to the immunomodulatory activity of beta-glycyrrhetinic acid, its effects on the classical and alternative activation pathways of human complement were investigated. We found that beta-glycyrrhetinic acid is a potent inhibitor of the classical complement pathway (IC50 = 35 microM), whereas no inhibitory activity was observed towards the alternative pathway (IC50 > 2500 microM). The anticomplementary activity of beta-glycyrrhetinic acid was dependent on its conformation, since the alpha-form was not active. It was also established that naturally occurring steroids, e.g. hydrocortisone and cortisone, did not inhibit human complement activity under similar conditions. Detailed mechanistic studies revealed that beta-glycyrrhetinic acid acts at the level of complement component C2.