Calcitonin gene related peptide and N-procalcitonin modulate CD11b upregulation in lipopolysaccharide activated monocytes and neutrophils

Altered immunity in migraine: a comprehensive scoping review

BACKGROUND

The pathogenesis of migraine remains unclear; however, a large body of evidence supports the hypothesis that immunological mechanisms play a key role. Therefore, we aimed to review current studies on altered immunity in individuals with migraine during and outside attacks.

METHODS

We searched the PubMed database to investigate immunological changes in patients with migraine. We then added other relevant articles on altered immunity in migraine to our search.

RESULTS

Database screening identified 1,102 articles, of which 41 were selected. We added another 104 relevant articles. We found studies reporting elevated interictal levels of some proinflammatory cytokines, including IL-6 and TNF-α. Anti-inflammatory cytokines showed various findings, such as increased TGF-β and decreased IL-10. Other changes in humoral immunity included increased levels of chemokines, adhesion molecules, and matrix metalloproteinases; activation of the complement system; and increased IgM and IgA. Changes in cellular immunity included an increase in T helper cells, decreased cytotoxic T cells, decreased regulatory T cells, and an increase in a subset of natural killer cells. A significant comorbidity of autoimmune and allergic diseases with migraine was observed.

CONCLUSIONS

Our review summarizes the findings regarding altered humoral and cellular immunological findings in human migraine. We highlight the possible involvement of immunological mechanisms in the pathogenesis of migraine. However, further studies are needed to expand our knowledge of the exact role of immunological mechanisms in migraine pathogenesis.

Differential regulation of cutaneous immunity by sensory neuron subsets

The nervous and immune systems have classically been studied as separate entities, but there is now mounting evidence for bidirectional communication between them in various organs, including the skin. The skin is an epithelial tissue with important sensory and immune functions. The skin is highly innervated with specialized subclasses of primary sensory neurons (PSNs) that can be in contact with skin-resident innate and adaptive immune cells. Neuroimmune crosstalk in the skin, through interactions of PSNs with the immune system, has been shown to regulate host cutaneous defense, inflammation, and tissue repair. Here, we review current knowledge about the cellular and molecular mechanisms involved in this crosstalk, as depicted via mouse model studies. We highlight the ways in which different immune challenges engage specialized subsets of PSNs to produce mediators acting on immune cell subsets and modulating their function.

Control of myeloid cell functions by nociceptors

The immune system has evolved to protect the host from infectious agents, parasites, and tumor growth, and to ensure the maintenance of homeostasis. Similarly, the primary function of the somatosensory branch of the peripheral nervous system is to collect and interpret sensory information about the environment, allowing the organism to react to or avoid situations that could otherwise have deleterious effects. Consequently, a teleological argument can be made that it is of advantage for the two systems to cooperate and form an “integrated defense system” that benefits from the unique strengths of both subsystems. Indeed, nociceptors, sensory neurons that detect noxious stimuli and elicit the sensation of pain or itch, exhibit potent immunomodulatory capabilities. Depending on the context and the cellular identity of their communication partners, nociceptors can play both pro- or anti-inflammatory roles, promote tissue repair or aggravate inflammatory damage, improve resistance to pathogens or impair their clearance. In light of such variability, it is not surprising that the full extent of interactions between nociceptors and the immune system remains to be established. Nonetheless, the field of peripheral neuroimmunology is advancing at a rapid pace, and general rules that appear to govern the outcomes of such neuroimmune interactions are beginning to emerge. Thus, in this review, we summarize our current understanding of the interaction between nociceptors and, specifically, the myeloid cells of the innate immune system, while pointing out some of the outstanding questions and unresolved controversies in the field. We focus on such interactions within the densely innervated barrier tissues, which can serve as points of entry for infectious agents and, where known, highlight the molecular mechanisms underlying these interactions.

A neutrophil-mediated carrier regulates tumor stemness by inhibiting autophagy to prevent postoperative triple-negative breast cancer recurrence and metastasis

Recurrence and metastasis after resection are still the main challenges in clinical treatment of breast cancer. Residual tumor and cancer stem-like cells are the primary culprits of recurrence and metastasis. Recent research studies indicate that autophagy is a cytoprotective mechanism of tumors, which maintains the stemness of cancer cells and promotes tumor proliferation and metastasis. Here, we constructed a "Trojan horse" using neutrophils as the carrier (PH-RL@NEs) to prevent the recurrence and metastasis of postoperative breast cancer. Neutrophils, as a "Trojan horse," can quickly respond to postoperative inflammation and accurately deliver drugs to the residual tumor site. The inflammation-triggered "Trojan horse" was then opened to release the liposomes containing the chemotherapeutic drug paclitaxel (PTX) and the autophagy inhibitor hydroxychloroquine (HCQ). We found that HCQ could effectively inhibit tumor cell autophagy, interfere with tumor epithelial-mesenchymal transition, and reduce the tumor stem cell-like population. In the orthotopic 4T1 postoperative recurrence models, PTX and HCQ synergistically killed tumors and regulated the stemness of tumor cells, thereby significantly inhibiting tumor recurrence and metastasis. Our work proved that the inhibition of autophagy to reduce tumor stemness is feasible and effective, which opens up a new prospect for postoperative tumor treatment. STATEMENT OF SIGNIFICANCE: The present study aimed to solve the issues of postoperative recurrence and metastasis of breast cancer and low efficiency of drug administration after surgery. For this purpose, we constructed neutrophils containing hydroxychloroquine (HCQ) and paclitaxel (PTX) co-loaded liposomes (PH-RL@NEs), which for the first time regulated the stemness of tumor cells by inhibiting autophagy, thereby inhibiting postoperative recurrence and metastasis of breast cancer cells. The results showed that PH-RL@NEs enhanced the targeted drug delivery efficiency, with the help of postoperative inflammation chemotaxis of neutrophils. HCQ effectively inhibited autophagy of tumor cells and reduced tumor stem cell-like cells, thus improving the therapeutic effect in the 4T1 in situ postoperative recurrence model.

Echinodorus macrophyllus: Hydroxycinnamoyl derivatives reduces neutrophil migration through modulation of cytokines, chemokines, and prostaglandin in the air-pouch model

ETHNOPHARMACOLOGICAL RELEVANCE

In Brazil, Echinodorus macrophyllus (Alismataceae), popularly known as chapéu-de-couro, is used to treat inflammatory diseases. Previous studies have shown a significant decrease in the acute inflammation for the aqueous extract of E. macrophyllus (AEEm) and its ethanolic fraction (Fr20).

AIM OF THE STUDY

This work fractionated Fr20, identified the fraction and substances responsible for the in vivo anti-inflammatory property, and demonstrated important immunomodulatory mechanisms of action.

MATERIALS AND METHODS

Fr20 was fractionated using Sephadex LH-20, and the most active fraction was chromatographically analyzed (HPLC-DAD and UPLC-ESI-TOF-MS). Leukotriene B4, Prostaglandin E2, and cytokines were determined by the enzyme-linked immunosorbent assay and in vivo acute inflammation by the air pouch model.

RESULTS

The subfractions SF1, SF3, and mainly the SF4 decreased NO levels (p < 0.05). SF3 and SF4 showed high DPPH scavenger activity. SF1 was more effective than SF4 in reducing vasodilation, redness, and leukocyte migration into the 4-h air pouch. SF1 inhibited 90.5% (100 mg/kg) and SF4 54.0% (50 mg/kg), mainly affecting the number of neutrophils. SF1 and SF4 reduced the protein level in the exudate. SF1 was also more effective in inhibiting neutrophil migration in a transwell assay (46.3%) and reduced (86.1%) the Leukotriene B4 level in the exudate. After five days of treatment, some SF1 anti-inflammatory mechanisms were evaluated in the air pouch's 24 h exudate and tissue. Despite the high level of inflammation of the control group in this condition, SF1 confirmed the decrease in the protein level and neutrophils migration into the pouch. It decreased the number of bone marrow cells, indicating a systemic effect of SF1. SF1 also decreased TNF-α (87%), IL-1β (77%), CKCL1/KC (71.3%), and PGE2 (97.8%) and increased IL-10 (74.1%) levels in the air pouch exudate. Phytochemical analysis of SF1 indicates mainly hydroxycinnamoyl derivatives.

CONCLUSION

Hydroxycinnamoyl derivatives present in SF1 are related to the crucial anti-inflammatory mechanisms of E. macrophyllus, decreasing the levels of TNF-α, IL-1β, CKCL1/KC, LTB4, and PGE2 on the exudate. These results explain the reduction of vasodilatation, erythema, and neutrophil migration into the air pouch model, confirming this plant's anti-inflammatory potential.

Sensory nerves promote corneal inflammation resolution via CGRP mediated transformation of macrophages to the M2 phenotype through the PI3K/AKT signaling pathway

OBJECTIVES

To explore the role of the corneal sensory nerves in Pseudomonas aeruginosa (P. aeruginosa) keratitis, the synergistic effect between the sensory neurons and macrophages in calcitonin gene-related peptide (CGRP) release, and the functional mechanisms of CGRP-mediated transformation of macrophages to the M2 phenotype.

METHODS

Corneal nerve loss, macrophage recruitment, and CGRP expression were evaluated. To explore the synergistic effect between the sensory neurons and macrophages, RAW 264.7 cells were challenged with lipopolysaccharide (LPS), then trigeminal ganglion (TG) sensory neurons were isolated and co-incubated with macrophages, and CGRP expression was tested. To investigate the biological function of cornea neuron-initiated immune responses mediated by CGRP, BIBN 4096BS was used to inhibit CGRP in vivo and α-CGRP was used to simulate CGRP in vitro. The expressions of inflammatory cytokines (IL-1β, IL-6, TNF-α, and IL-10), M1 (CD80/CD86), M2 (CD163/CD206) macrophage markers, and signal transducers (PI3K/AKT) were detected.

RESULTS

P. aeruginosa infection induced corneal nerve loss, macrophage recruitment, and CGRP up-expression. CGRP was co-localized with macrophages. Co-culture showed that sensory neurons and macrophages can mediate CGRP release. More CGRP was released when the two types of cells were combined to respond to LPS. BIBN 4096BS promoted pro-inflammatory cytokines and inhibited the anti-inflammatory cytokines and signal transducers, while, α-CGRP inhibited the pro-inflammatory cytokines and M1 markers and promoted the anti-inflammatory cytokine, M2 markers, and signal transducers.

CONCLUSIONS

P. aeruginosa infection induces corneal sensory neuron activation, macrophage recruitment, and CGRP up-expression. The synergistic effect between the sensory neurons and macrophages promotes CGRP release. CGRP inhibits corneal inflammation and promotes the transformation of macrophages to the M2 phenotype through the PI3K/AKT signaling pathway.

The Role of Galanin during Bacterial Infection in Larval Zebrafish

Galanin is a peptide that is conserved among different species and plays various roles in an organism, although its entire role is not completely understood. For many years, galanin has been linked mainly with the neurotransmission in the nervous system; however, recent reports underline its role in immunity. Zebrafish (Danio rerio) is an intensively developing animal model to study infectious diseases. In this study, we used larval zebrafish to determine the role of galanin in bacterial infection. We showed that knockout of galanin in zebrafish leads to a higher bacterial burden and mortality during Mycobacterium marinum and Staphylococcus aureus infection, whereas administration of a galanin analogue, NAX 5055, improves the ability of fish to control the infection caused by both pathogens. Moreover, the transcriptomics data revealed that a lower number of genes were regulated in response to mycobacterial infection in gal−/− mutants compared with their gal+/+ wild-type counterparts. We also found that galanin deficiency led to significant changes in immune-related pathways, mostly connected with cytokine and chemokine functions. The results show that galanin acts not only as a neurotransmitter but is also involved in immune response to bacterial infections, demonstrating the complexity of the neuroendocrine system and its possible connection with immunity.

Protective Role of Galanin during Chemically Induced Inflammation in Zebrafish Larvae

During a pathological condition, many different systems are involved in the response of an affected organism. Galanin is considered to be a neuropeptide that plays an important role in the central nervous system; however, it is involved in many other biological processes, including the immune response. During our studies, we showed that galanin became upregulated in zebrafish larvae when exposed to copper sulfate. Moreover, the presence of normal levels of galanin, administration of a galanin analog NAX 5055 or galanin overexpression led to lowered lateral line damage and enhanced expression of inflammatory markers compared to the knockout larvae. The results showed that the neuroendocrine system acts multifunctionally and should be considered as a part of the complex neuro-immune-endocrine axis.

Deficiency of Calcitonin Gene-Related Peptide Affects Macrophage Polarization in Osseointegration

Macrophages have been described as a critical cell population regulating bone regeneration and osseointegration, and their polarization phenotype is of particular importance. Several studies have shown that calcitonin gene-related peptide-α (CGRP) might modulate macrophage polarization in inflammatory response and bone metabolism. This study aimed to investigate the effect of CGRP on macrophage polarization in titanium osseointegration. In vitro, bone marrow-derived macrophages (BMDMs) from C57BL/6 or CGRP^–/– mice were obtained and activated for M1 and M2 polarization. Flow cytometry and real-time PCR were used to evaluate the M1/M2 polarization and inflammatory function. In vivo, mice were divided into 3 groups: wild-type, CGRP^–/–, and CGRP^–/– mice with CGRP lentivirus. After extraction of the maxillary first molar, 0.6 mm × 1.25 mm titanium implants were emplaced. Bone formation and inflammation levels around implants were then observed and analyzed. The results of flow cytometry demonstrated that CGRP deficiency promoted M1 polarization and inhibited M2 polarization in BMDMs, which was consistent with pro-inflammatory and anti-inflammatory cytokine expression levels in real-time PCR. In vivo, compared with the CGRP^–/– group, the CGRP gene transfection group displayed better osseointegration and lower inflammation levels, close to those of the wild-type group. These results revealed that CGRP might play roles in macrophage polarization. In addition, CGRP deficiency could inhibit osseointegration in murine maxillae, while CGRP recovery by lentivirus transfection could improve osseointegration and regulate macrophage phenotype expression.

Flavonoid-enriched fraction from Echinodorus macrophyllus aqueous extract exhibits high in-vitro and in-vivo anti-inflammatory activity

Objectives

Echinodorus macrophyllus (Kunth) Micheli (Alismataceae) is popularly used as an infusion to treat inflammatory diseases. This work fractionated the aqueous extract of E. macrophyllus (AEEm) to improve its anti-inflammatory effects.

Methods

Aqueous extract of E. macrophyllus was fractionated by Sephadex LH-20 and analysed by HPLC-DAD. Anti-inflammatory action was evaluated, in vivo, by air pouch model (total leucocyte, protein and leukotriene B4 (LTB4)), and, in vitro, by neutrophil migration (transwell assay) and its Mac1 expression (flow cytometry), and RAW 264.7 nitric oxide (NO) production (Griess reaction).

Key findings

Fr20 reduced total leucocyte at 2.5 mg/kg (29.7%) while ethanolic extract of E. macrophyllus (EAEm) increased it (94.0%). Fr20 showed higher (P &lt; 0.05) inhibition (89.8%) of LTB4 in exudate than EAEm (75.0%). Fr20 and EAEm decreased exudate protein and inflammatory infiltrate in pouch tissues, in-vitro neutrophil migration, and NO production. Otherwise, Fr40 did not reduce leucocytes and exudate protein (until 50 mg/kg) nor tissue inflammation, and increased in-vitro NO production. The inhibition of neutrophil migration by EAEm, but not Fr20, was dependent on reduced Mac-1 expression.

Conclusions

The fractionation of AEEm provided a more potent anti-inflammatory fraction containing flavonoids (Fr20) that reduces the migration of neutrophils and LTB4 release, probably contributing to its mechanism of action.

Elevated Serum PCT in Septic Shock With Endotoxemia Is Associated With a Higher Mortality Rate

To examine the effect of endotoxemia on the procalcitonin (PCT) serum levels and mortality rates of adult patients with septic shock diagnosed on the day of admission to the intensive care unit (ICU).A retrospective observational study was performed over a 2-year period. Levels of PCT were compared for septic shock patients with and without endotoxemia on admission to the ICU. Endotoxemia was identified with an Endotoxin Activity Assay.One hundred fifty-seven patients with septic shock were enrolled into the study. Group 1 consisted of patients with elevated endotoxin activity (EA) (n = 95, EA = 0.57 endotoxin activity unit [EAU] [0.46-0.67]) and Group 2 consisted of patients with low EA (n = 62, EA = 0.27 EAU [0.17-0.36]). Acute Physiology And Chronic Health Evaluation II (APACHE II) score and SOFA score were similar in both groups (APACHE II = 23 [16-29] and 19 [16-25]; Sequential Organ Failure Assessment [SOFA] = 10 [7-13] and 11 [8-12] in Groups 1 and 2, respectively) (nonsignificant). The PCT level was 6 times higher in Group 1 than in Group 2 (19.6 ng/mL vs. 3.1 ng/mL, P < 0.001). There was a strong correlation between EA and serum PCT (P < 0.001, R = 0.5). The presence of endotoxemia on admission to the ICU was associated with an increased mortality rate: 52% in the group of patients with endotoxemia and 25% in the group without endotoxemia. EA in survivors was 0.39 EAU (0.26-0.57) and 0.53 EAU (0.4-0.61) in nonsurvivors (P = 0.004). The median PCT level in survivors was 6.7 ng/mL (2.3-28.0), compared with 16.7 ng/mL (5.3-31.0) in nonsurvivors (P = 0.04).This observational study revealed that endotoxemia in patients with septic shock on admission to the ICU was frequently found and was associated with an elevated PCT level and a high mortality rate. Endotoxemia was a common occurrence in patients with septic shock, regardless of the infecting microorganism.

Galanin modulates human and murine neutrophil activation in vitro

AIMS

Polymorphonuclear neutrophils are key players in innate immunity. The innate immune system needs to be tightly controlled to ensure proper activation but also no overactivation. Galanin has been shown to regulate inflammatory reactions, and therefore, we aimed to elucidate the expression of galanin and its three receptors (GAL1 -GAL3 ) in polymorphonuclear neutrophils and to evaluate whether galanin exerts direct or indirect effects on human and murine polymorphonuclear neutrophils.

METHODS

Human peripheral polymorphonuclear neutrophils were isolated from fresh blood of healthy donors, and murine polymorphonuclear neutrophils were isolated from bone marrow of C57BL/6N mice. Gene expression was evaluated by qRT-PCR. As a marker for polymorphonuclear neutrophil activation, CD11b integrin surface expression was measured by FACS analysis. Furthermore, a label-free technology measuring ligand-induced dynamic mass redistribution was used to evaluate the response of polymorphonuclear neutrophils to galanin.

RESULTS

GAL2 receptor expression was found in both human and murine polymorphonuclear neutrophils, galanin and GAL3 receptor were exclusively expressed in murine bone marrow polymorphonuclear neutrophils, and GAL1 receptor was not detectable in polymorphonuclear neutrophils of either species. Galanin treatment was not able to induce CD11b integrin surface expression or dynamic mass redistribution in human polymorphonuclear neutrophils and murine bone marrow polymorphonuclear neutrophils. However, galanin treatment significantly enhanced the response of polymorphonuclear neutrophils of both species to interleukin-8.

CONCLUSION

Galanin can be regarded as an immunomodulatory peptide as it can sensitize polymorphonuclear neutrophils towards pro-inflammatory cytokines in humans and mice.

Calcitonin gene-related peptide: physiology and pathophysiology

Calcitonin gene-related peptide (CGRP) is a 37-amino acid neuropeptide. Discovered 30 years ago, it is produced as a consequence of alternative RNA processing of the calcitonin gene. CGRP has two major forms (α and β). It belongs to a group of peptides that all act on an unusual receptor family. These receptors consist of calcitonin receptor-like receptor (CLR) linked to an essential receptor activity modifying protein (RAMP) that is necessary for full functionality. CGRP is a highly potent vasodilator and, partly as a consequence, possesses protective mechanisms that are important for physiological and pathological conditions involving the cardiovascular system and wound healing. CGRP is primarily released from sensory nerves and thus is implicated in pain pathways. The proven ability of CGRP antagonists to alleviate migraine has been of most interest in terms of drug development, and knowledge to date concerning this potential therapeutic area is discussed. Other areas covered, where there is less information known on CGRP, include arthritis, skin conditions, diabetes, and obesity. It is concluded that CGRP is an important peptide in mammalian biology, but it is too early at present to know if new medicines for disease treatment will emerge from our knowledge concerning this molecule.

Association of autophagy-related 16-like 1 (ATG16L1) gene polymorphism with sepsis severity in patients with sepsis and ventilator-associated pneumonia

Autophagy is a highly conserved mechanism of eukaryotic cells implicated in cell homeostasis and elimination of intracellular pathogens. Functional polymorphisms in genes encoding for autophagy have been associated with susceptibility to inflammatory and infectious diseases, but data on severe infections are missing. The aim of the present study was to assess whether polymorphisms in genes encoding proteins involved in autophagy influence susceptibility to ventilator-associated pneumonia (VAP). Mechanically ventilated patients with VAP were studied. Genotyping for autophagy-related 16-like 1 (ATG16L1, rs2241880) functional polymorphism was performed using the TaqMan single-nucleotide assay. Monocytes were isolated from patients and stimulated with lipopolysaccharide (LPS). Tumor necrosis factor-α (TNF-α) was measured in the supernatants of monocytes using an enzyme-linked immunosorbent assay. Procalcitonin (PCT) was also measured in the serum of patients by an immuno-time-resolved amplified cryptate technology assay. A total of 155 patients with VAP were enrolled in the study. Carriage of the minor A allele of ATG16L1 was associated with septic shock with at least one organ failure (odds ratio (OR): 2.40, p: 0.036). TNF-α production was significantly greater among the carriers of the polymorphism presenting with at least one organ failure (p: 0.040). PCT was increased upon worsening to septic shock and organ failure only among carriers of the minor frequency A alleles. In a homogeneous cohort of septic patients with VAP, the carriage of autophagy polymorphisms predisposes to VAP severity and septic shock development. This may be related with predisposition to immunoparalysis.

Calcitonin gene-related peptide is a key neurotransmitter in the neuro-immune axis

The question of how the neural and immune systems interact in host defense is important, integrating a system that senses the whole body with one that protects. Understanding the mechanisms and routes of control could produce novel and powerful ways of promoting and enhancing normal functions as well as preventing or treating abnormal functions. Fragmentation of biological research into specialities has resulted in some failures in recognizing and understanding interactions across different systems and this is most striking across immunology, hematology, and neuroscience. This reductionist approach does not allow understanding of the in vivo orchestrated response generated through integration of all systems. However, many factors make the understanding of multisystem cross-talk in response to a threat difficult, for instance the nervous and immune systems share communication molecules and receptors for a wide range of physiological signals. But, it is clear that physical, hard-wired connections exist between the two systems, with the key link involving sensory, unmyelinated nerve fibers (c fibers) containing the neuropeptide calcitonin gene-related peptide (CGRP), and modified macrophages, mast cells and other immune and host defense cells in various locations throughout the body. In this review we will therefore focus on the induction of CGRP and its key role in the neuroimmune axis.

Procalcitonin as a biomarker of acute lower respiratory tract infections

BACKGROUND

Procalcitonin (PCT) has emerged as a promising 'acute phase' biomarker used for diagnosis of acute bacterial infections of the respiratory tract. The introduction of new sensitive PCT assays has facilitated implementation of a new clinical approach to reduce antibiotic use in acute lower respiratory tract infections (LRTIs), without compromising patient safety.

OBJECTIVE

Current state of knowledge on the clinical usefulness of serum PCT measurements for the evaluation of acute LRTIs is presented herein, together with basic information on available rapid diagnostic tests for PCT measurement.

METHODS

During the literature search the emphasis was on PCT use as a diagnostic, monitoring and prognostic tool for acute LRTIs. The acute LRTIs have been defined as acute bronchitis, acute exacerbations of chronic obstructive pulmonary disease or asthma, and pneumonia. Original studies involving patients with these conditions have been considered, and recent articles documenting interventional trials on PCT use for guidance of antimicrobial treatment in LRTIs have been reviewed in particular.

RESULTS/CONCLUSION

When measured with sensitive and rapid assays, PCT has proved to be a good biomarker for acute bacterial LRTIs, which enables an early diagnosis, facilitates therapeutic decisions, and can inform clinicians about the course of disease and prognosis. PCT can become a particularly suitable tool for implementation in an emergency and acute medical care setting.

Procalcitonin neutralizes bacterial LPS and reduces LPS-induced cytokine release in human peripheral blood mononuclear cells

BACKGROUND

Procalcitonin (PCT) is a polypeptide with several cationic aminoacids in its chemical structure and it is a well known marker of sepsis. It is now emerging that PCT might exhibit some anti-inflammatory effects. The present study, based on the evaluation of the in vitro interaction between PCT and bacterial lipopolisaccharide (LPS), reports new data supporting the interesting and potentially useful anti-inflammatory activity of PCT.

RESULTS

PCT significantly decreased (p < 0.05) the limulus amoebocyte lysate (LAL) assay reactivity of LPS from both Salmonella typhimurium (rough chemotype) and Escherichia coli (smooth chemotype). Subsequently, the in vitro effects of PCT on LPS-induced cytokine release were studied in human peripheral blood mononuclear cells (PBMC). When LPS was pre-incubated for 30 minutes with different concentrations of PCT, the release of interleukin-10 (IL-10) and tumor necrosis factor alpha (TNFα) by PBMC decreased in a concentration-dependent manner after 24 hours for IL-10 and 4 hours for TNFα. The release of monocyte chemotactic protein-1 (MCP-1) exhibited a drastic reduction at 4 hours for all the PCT concentrations assessed, whereas such decrease was concentration-dependent after 24 hours.

CONCLUSIONS

This study provides the first evidence of the capability of PCT to directly neutralize bacterial LPS, thus leading to a reduction of its major inflammatory mediators.

Immunoneutralization of the aminoprocalcitonin peptide of procalcitonin protects rats from lethal endotoxaemia: neuroendocrine and systemic studies

Severe sepsis and septic shock are an important cause of mortality and morbidity. These illnesses can be triggered by the bacterial endotoxin LPS (lipopolysaccharide) and pro-inflammatory cytokines, particularly TNF-α (tumour necrosis factor-α) and IL (interleukin)-1β. Severity and mortality of sepsis have also been associated with high concentrations of N-PCT (aminoprocalcitonin), a 57-amino-acid neuroendocrine peptide derived from ProCT (procalcitonin). Previous studies in a lethal model of porcine polymicrobial sepsis have revealed that immunoneutralization with IgG that is reactive to porcine N-PCT significantly improves short-term survival. To explore further the pathophysiological role of N-PCT in sepsis, we developed an antibody raised against a highly conserved amino acid sequence of human N-PCT [N-PCT-(44-57)]. This sequence differs by only one amino acid from rat N-PCT. First, we demonstrated the specificity of this antibody in a well-proven model of anorexia induced in rats by central administration of human N-PCT-(1-57). Next we explored further the therapeutic potential of anti-N-PCT-(44-57) in a rat model of lethal endotoxaemia and determined how this immunoneutralization affected LPS-induced lethality and cytokine production. We show that this specific antibody inhibited the LPS-induced early release of TNF-α and IL-1β and increased survival, even if treatment began after the cytokine response had occurred. In addition, anti-N-PCT-(44-57) may increase long-term survival in LPS-treated rats by up-regulating the late production of counter-regulatory anti-inflammatory mediators such as ACTH (adrenocorticotropic hormone) and IL-10. In conclusion, these results support N-PCT as a pro-inflammatory factor in both the early and the late stages of lethal endotoxaemia, and suggest anti-N-PCT as a candidate for septic shock therapy.

Exogenous procalcitonin evokes a pro-inflammatory cytokine response

OBJECTIVE AND DESIGN

Procalcitonin (ProCT) is increased in serum of septic patients and those with systemic inflammation. Endogenous levels of ProCT might influence the response of polymorphonuclear leukocytes (PMNs), independently of endotoxin, in clinical disease.

SUBJECTS

Healthy human volunteers.

TREATMENT

Recombinant human ProCT (rhProCT).

METHODS

Whole blood and PMNs were exposed in vitro to exogenous rhProCT. Interleukin (IL)-6, IL-8, IL-10, IL-13, tumor necrosis factor-alpha (TNFα), IL-1β, and macrophage inflammatory protein (MIP)-1β (pg/ml) were measured by multiplex suspension bead-array immunoassay, and migration and phagocytosis were measured in PMNs.

RESULTS

In a whole-blood model, a dose-dependent increase in IL-6, TNFα, and IL-1β of the cell-free supernatant was noted. Pre-incubation with ProCT, at doses consistent with clinical sepsis, resulted in a decrease in PMN migration without alteration in phagocytosis of Staphylococcus aureus or indirect measurements of bacterial killing.

CONCLUSION

Clinically relevant levels of ProCT influence immunologic responses that may contribute to systemic inflammatory response and septic shock.

Protective effects and anti-inflammatory pathways of exogenous calcitonin gene-related peptide in severe necrotizing pancreatitis

BACKGROUND

Microcirculatory disturbances are known to play a pivotal role in the pathogenesis of severe necrotizing pancreatitis (SNP). Calcitonin gene-related peptide (CGRP) is a vasodilatatory neuropeptide with potential anti-inflammatory effects. This study characterizes the protective effects and the anti-inflammatory pathway of exogenous CGRP in SNP.

METHODS

SNP was induced in rats using the glycodeoxycholic acid model. CGRP was injected prophylactically before or therapeutically after initiation of the disease. Pancreatic damage was assessed using intravital microscopy, histology, NF-kappaB p50/p65 electrophoretic mobility shift assay, serum cytokine assay and ICAM-1 immunohistochemistry at 6 or 12 h after the onset of disease.

RESULTS

Pancreatic microcirculatory disturbances, nuclear NF-kappaB levels and pancreatic ICAM-1 expression were increased in SNP compared to controls. After CGRP application, microcirculatory disturbances, NF-kappaB levels and pancreatic ICAM-1 expression were attenuated compared to pancreatitis alone. Moreover, pancreatic morphologic damage was significantly reduced by both prophylactic and therapeutic application of CGRP.

CONCLUSIONS

CGRP is a neuropeptide that ameliorates the development of SNP in rats and may provide new treatment options. Its anti-inflammatory effects appear to be mediated by the modulation of pancreatic microcirculation and the inflammatory cascade.

Serum concentrations of procalcitonin after cardiac surgery

BACKGROUND AND AIM

Monitoring of complications in patients undergoing cardiac surgery may be difficult because cardiopulmonary bypass (CPB) can lead to a systemic inflammatory response syndrome because of exposure of blood to nonphysiological surfaces. The purpose of the study was to establish the baseline levels of procalcitonin (PCT) after cardiac surgery in our population in order to analyze a possible induction of the inflammatory response that might interfere with the diagnosis of infection by PCT.

METHODS

Serum samples from patients undergoing coronary artery bypass grafting or valve replacement were collected at the time of admission to intensive care unit, after surgery as well as in the first and second postoperative days. Patients were followed for the development of postoperative complications. PCT levels were measured by immunoluminometric assay.

RESULTS

The mean PCT values were significantly higher in the first postoperative day in all the groups except the control group. No increased PCT levels were found related neither to duration of CPB, nor to time of aortic clamping. Only patients who presented complications had significantly increased PCT values immediately after surgery (p = 0.004), in the first postoperative day (p < 0.0001), and in the second postoperative day (p < 0.0001) with respect to those who recovered uneventfully.

CONCLUSIONS

A slight and transient increase in PCT levels was observed in the first postoperative day after cardiac surgery. Significant elevation of PCT was only observed when complications were present.

Examination of the effect of procalcitonin on human leucocytes and the porcine isolated coronary artery

BACKGROUND

The aim of this study was to investigate the effects of procalcitonin on the lipopolysaccharide (LPS)-induced changes in human leucocytes and porcine isolated coronary artery.

METHODS

Using flow cytometry, changes in forward scatter and intracellular calcium in human neutrophils and monocytes were determined after exposure to procalcitonin, calcitonin gene-related peptide (CGRP), LPS, and the known chemoattractants formylated methionine-leucine-phenylalanine (fMLP) and interleukin-8 (IL-8). In porcine isolated coronary artery, the effects of procalcitonin were evaluated using the contractile function change and the release of TNFalpha.

RESULTS

In human neutrophils and monocytes, procalcitonin (100 nM), but not CGRP, increased forward scatter and the expression of surface markers (CD16 and CD14, respectively) in a similar manner to 10 microg ml(-1) LPS. Procalcitonin, but not CGRP, also increased the proportion of cells exhibiting an increase in intracellular calcium ions similar to that produced by fMLP and IL-8. Acute exposure of the coronary artery to procalcitonin produced a small, endothelium-independent relaxation (approximately 15% of constrictor tone), but failed to modify subsequent relaxations to CGRP. After 16 h exposure, procalcitonin (100 nM) increased TNFalpha release from the coronary artery equivalent to 70% of that produced by LPS, but did not modify the inhibitory effect of LPS (100 microg ml(-1)) on contractile responses.

CONCLUSIONS

Procalcitonin has a proinflammatory effect on human leucocytes and porcine coronary artery, but it is not capable of modulating LPS-induced changes in vascular responsiveness in vitro.

The cyclic AMP-Epac1-Rap1 pathway is dissociated from regulation of effector functions in monocytes but acquires immunoregulatory function in mature macrophages

cAMP mediates its intracellular effects through activation of protein kinase A (PKA), nucleotide-gated ion channels, or exchange protein directly activated by cAMP (Epac). Although elevation of cAMP in lymphocytes leads to suppression of immune functions by a PKA-dependent mechanism, the effector mechanisms for cAMP regulation of immune functions in monocytes and macrophages are not fully understood. In this study, we demonstrate the presence of Epac1 in human peripheral blood monocytes and activation of Rap1 in response to cAMP. However, by using an Epac-specific cAMP analog (8-CPT-2'-O-Me-cAMP), we show that monocyte activation parameters such as synthesis and release of cytokines, stimulation of cell adhesion, chemotaxis, phagocytosis, and respiratory burst are not regulated by the Epac1-Rap1 pathway. In contrast, activation of PKA by a PKA-specific compound (6-Bnz-cAMP) or physiological cAMP-elevating stimuli like PGE(2) inhibits monocyte immune functions. Furthermore, we show that the level of Epac1 increases 3-fold during differentiation of monocytes into macrophages, and in monocyte-derived macrophages cAMP inhibits FcR-mediated phagocytosis via both PKA and the Epac1-Rap1 pathway. However, LPS-induced TNF-alpha production is only inhibited through the PKA pathway in these cells. In conclusion, the Epac1-Rap1 pathway is present in both monocytes and macrophages, but only regulates specific immune effector functions in macrophages.

PDE4 inhibitors as new anti-inflammatory drugs: effects on cell trafficking and cell adhesion molecules expression

Phosphodiesterase 4 (PDE4) is a major cyclic AMP-hydrolyzing enzyme in inflammatory and immunomodulatory cells. The wide range of inflammatory mechanisms under control by PDE4 points to this isoenzyme as an attractive target for new anti-inflammatory drugs. Selective inhibitors of PDE4 have demonstrated a broad spectrum of anti-inflammatory activities including the inhibition of cellular trafficking and microvascular leakage, cytokine and chemokine release from inflammatory cells, reactive oxygen species production, and cell adhesion molecule expression in a variety of in vitro and in vivo experimental models. The initially detected side effects, mainly nausea and emesis, appear at least partially overcome by the 'second generation' PDE4 inhibitors, some of which like roflumilast and cilomilast are in the later stages of clinical development for treatment of chronic obstructive pulmonary disease. These new drugs may also offer opportunities for treatment of other inflammatory diseases.

Modulation and Source of Procalcitonin in Reduced Renal Function and Renal Replacement Therapy

Serum procalcitonin (PCT), an accurate marker of severe infection, is moderately increased in chronic kidney disease (CKD), peritoneal dialysis (PD) and haemodialysis (HD). We studied the extent of PCT elevation and factors accounting for elevated PCT in CKD and dialysis, and whether peripheral blood mononuclear cells (PBMC) contribute to increased PCT. In 37 controls, 281 CKD, 31 PD, and 65 HD patients without infection, PCT was measured and correlated with CKD stage, PD, HD, C-reactive protein (CRP), cardiovascular disease (CVD) and other clinical parameters. PCT release by PBMC from controls, advanced CKD, PD and HD patients (12 subjects each) was measured. PCT increased in parallel to the deterioration of CKD. Oliguria, advanced CKD, PD, HD, CVD and elevated CRP were independently associated with PCT elevation. PCT release from PBMC significantly increased in advanced CKD, PD and HD. PCT release from PBMC correlated closely with the corresponding serum PCT values (r=0.76, P <0.001). In the absence of infection, PCT may increase due to reduced renal elimination and increased synthesis, as due to PBMC. Furthermore, serum PCT could serve as a marker of low-grade inflammation and CVD, which substantially increase mortality in CKD and dialysis.

Small-dose capsaicin reduces systemic inflammatory responses in septic rats

We investigated the influence of small- and large-dose capsaicin in modulating systemic inflammatory responses during different stages of sepsis in rats. Rats were divided into six groups: group C, control; group S, sepsis; group CLC, small dose of capsaicin (1 mg/kg subcutaneously); group SLC, small dose of capsaicin plus sepsis; group CHC, large dose of capsaicin (150 mg/kg subcutaneously); group SHC, large dose of capsaicin plus sepsis. Rats were made septic by cecal ligation and puncture (CLP). Each group was subdivided into two subgroups. The animals were killed at 9 or 18 h after CLP. Plasma concentrations of calcitonin gene-related peptide (CGRP), tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-10, and total nitrite/nitrate (NOx) were measured. Superoxide dismutase and malondialdehyde (MDA) were determined in liver, lung, and heart tissues. CGRP was increased in groups S, CLC, and SLC when compared with the other groups. In the SLC group, plasma concentrations of TNF-alpha, IL-6, NOx, and tissue MDA levels were reduced and IL-10 level was increased when compared with groups S and SHC 18 h after CLP (P < 0.05). Small-dose capsaicin treatment increased antiinflammatory IL-10 levels and attenuated the increases in proinflammatory cytokines, NOx, and tissue MDA in septic rats.

Vascular Actions of Calcitonin Gene-Related Peptide and Adrenomedullin

This review summarizes the receptor-mediated vascular activities of calcitonin gene-related peptide (CGRP) and the structurally related peptide adrenomedullin (AM). CGRP is a 37-amino acid neuropeptide, primarily released from sensory nerves, whilst AM is produced by stimulated vascular cells, and amylin is secreted from the pancreas. They share vasodilator activity, albeit to varying extents depending on species and tissue. In particular, CGRP has potent activity in the cerebral circulation, which is possibly relevant to the pathology of migraine, whilst vascular sources of AM contribute to dysfunction in cardiovascular disease. Both peptides exhibit potent activity in microvascular beds. All three peptides can act on a family of CGRP receptors that consist of calcitonin receptor-like receptor (CL) linked to one of three receptor activity-modifying proteins (RAMPs) that are essential for functional activity. The association of CL with RAMP1 produces a CGRP receptor, with RAMP2 an AM receptor and with RAMP3 a CGRP/AM receptor. Evidence for the selective activity of the first nonpeptide CGRP antagonist BIBN4096BS for the CGRP receptor is presented. The cardiovascular activity of these peptides in a range of species and in human clinical conditions is detailed, and potential therapeutic applications based on use of antagonists and gene targeting of agonists are discussed.

Procalcitonin: improved biochemical severity stratification and postoperative monitoring in severe abdominal inflammation and sepsis

BACKGROUND

Infections and sepsis are among the most devastating complications in abdominal surgery and significantly contribute to morbidity and mortality. Early and reliable diagnosis of septic complications is notoriously difficult, and the search for novel approaches to overcome this problem is still a compelling issue for clinicians. Among a large array of inflammatory parameters, procalcitonin (PCT), the 116-amino-acid pro-peptide of calcitonin, has gained considerable importance in identifying patients at risk of developing infection and sepsis in clinical practice.

METHODS

Along with the latest insights into pathophysiological aspects of this pro-hormone, the literature as well as our own experience on the usefulness of PCT determinations in patients with severe inflammatory abdominal disorders was reviewed.

RESULTS

Although the term "sepsis" does not embrace the integral properties of PCT, a remarkable number of clinical studies have demonstrated the pivotal role of this parameter in the host response to microbial and fungal infections. In acute pancreatitis PCT allows early severity stratification and closely correlates with the development of subsequent pancreatic infections. In patients with peritonitis PCT reflects overall disease severity and is an early and reliable indicator of overall prognosis. Postoperative monitoring of PCT is a helpful tool to identify patients with evolving or persisting septic complications after elective and emergency abdominal surgery.

CONCLUSIONS

Compared with established biochemical routine variables, PCT significantly contributes to earlier and better stratification of patients at risk of developing septic complications and provides excellent prognostic assessment in severe abdominal inflammation. The currently available test systems render PCT an applicable and readily available parameter under clinical routine and emergency conditions.