The antimicrobial peptide HBD-2 and the Toll-like receptors-2 and -4 are induced in synovial membranes in case of septic arthritis

Characterization of Tissue Immunity Defense Factors of the Lip in Primary Dentition Children with Bilateral Cleft Lip Palate

BACKGROUND

Bilateral cleft lip palate is a severe congenital birth defect of the mouth and face. Immunity factors modulate immune response, inflammation, and healing; therefore, they are vital in the assessment of the immunological status of the patient. The aim of this study is to assess the distribution of Gal-10, CD-163, IL-4, IL-6, IL-10, HBD-2, HBD-3, and HBD-4 in tissue of the bilateral cleft lip palate in primary dentition children.

METHODS

Five patients underwent cheiloplasty surgery, where five tissue samples of lip were obtained. Immunohistochemical staining, semi-quantitative evaluation, and non-parametric statistical analysis were used.

RESULTS

A statistically significant increase in HBD-2, HBD-3, and HBD-4 was found in skin and mucosal epithelium, hair follicles, and blood vessels. A notable increase was also noted in IL-4, IL-6, and IL-10 in the mucosal epithelium and CD163 in blood vessels. The connective tissue of patients presented with a statistically significant decrease in Gal-10, IL-10, and HBD-3. Spearman's rank correlation revealed multiple significant positive and negative correlations between the factors.

CONCLUSIONS

Upregulation of CD163 points to increased angiogenesis but the increase in IL-4 and IL-10 as well as the decrease in Gal-10 points to suppression of excessive inflammatory damage. Decreased connective tissue healing and excessive scarring are suggested by the decrease in HBD-3 and IL-10 and the increase in IL-6.

Potential Pathogenetic Role of Antimicrobial Peptides Carried by Extracellular Vesicles in an in vitro Psoriatic Model

Purpose

Extracellular Vesicles (EVs) are a heterogeneous group of cell-derived membranous nanoparticles involved in several physiopathological processes. EVs play a crucial role in the definition of the extracellular microenvironment through the transfer of their cargo. Psoriasis is a prototypical chronic inflammatory disease characterized by several secreted mediators, among which antimicrobial peptides (AMPs) are considered pivotal in the development of the psoriatic inflammatory microenvironment. The role of EVs in the pathogenesis of psoriasis has not been elucidated yet, even if emerging evidence demonstrated that interleukin-17A (IL-17A), the psoriasis-related principal cytokine, modifies EVs release and cargo content. The aim of this work was to analyze whether, besides IL-17A, other psoriasis-related cytokines (ie, IFN-γ, TNF-α, IL-22 and IL-23) could affect EVs release and their AMPs mRNAs cargo as well as to analyze the potential biological effect due to EVs internalization by different acceptor cells.

Methods

Nanoparticle tracking analysis (NTA) was performed on supernatants of HaCaT cells stimulated with IL-17A, IFN-γ, TNF-α, IL-22 or IL-23 to enumerate EVs. Real-Time RT-PCR was used for gene expression analysis in cells and EVs. Confocal microscopy and Flow cytometry were used to, respectively, study Netosis and EVs internalization.

Results

IL-17A and IFN-γ increased EVs release by HaCaT cells. All the tested cytokines modulated AMPs mRNA expression in parental cells and in their respective EVs. S100A12 and hBD2 mRNAs were upregulated following IL-17A and IL-22 treatments. Interestingly, EVs derived from cytokine treated HaCaT cells induced Netosis in freshly isolated neutrophils. Upregulation of S100A12 and hBD2 mRNA was also detectable in acceptor cells incubated with EVs derived from cells treated with psoriasis-related cytokines.

Conclusion

The obtained results highlighted the role of EVs in the composition of psoriasis-associated secretome and microenvironment also suggesting the EV involvement in the spreading of the disease mediators and in the possible associated comorbidities.

Glycosaminoglycan, Antimicrobial Defence Molecule and Cytokine Appearance in Tracheal Hyaline Cartilage of Healthy Humans

Hyaline cartilage is an important tracheal structure, yet little is known about its molecular composition, complicating investigation of pathologies and replacement options. Our aim was to research tracheal hyaline cartilage structure, protective tissue factors and variations in healthy humans. The tissue material was obtained from 10 cadavers obtained from the Riga Stradins University Institute of Anatomy and Anthropology archive. Tissues were stained with Bismarck brown and PAS for glycosaminoglycans, and immunohistochemistry was performed for HBD-2, HBD-3, HBD-4, IL-10 and LL-37. The slides were inspected by light microscopy and Spearman's rank correlation coefficient was calculated. The extracellular matrix was positive across hyaline cartilage for PAS, yet Bismarck brown marked positive proliferation and growth zones. Numerous positive cells for both factors were found in all zones. All of the antimicrobial defence molecules and cytokines were found in a moderate number of cells, except in the mature cell zone with few positive cells. Spearman's rank correlation coefficient revealed strong and moderate correlations between studied factors. Hyaline cartilage is a tracheal defence structure with a moderate number of antimicrobial defence protein and cytokine immunoreactive cells as well as numerous glycosaminoglycan positive cells. The extracellular matrix glycosaminoglycans provide structural scaffolding and intercellular signalling. The correlations between the studied factors confirm the synergistic activity of them.

Novel therapeutic interventions towards improved management of septic arthritis

Septic arthritis (SA) represents a medical emergency that needs immediate diagnosis and urgent treatment. Despite aggressive treatment and rapid diagnosis of the causative agent, the mortality and lifelong disability, associated with septic arthritis remain high as close to 11%. Moreover, with the rise in drug resistance, the rates of failure of conventional antibiotic therapy have also increased. Among the etiological agents frequently isolated from cases of septic arthritis, Staphylococcus aureus emerges as a dominating pathogen, and to worsen, the rise in methicillin-resistant S. aureus (MRSA) isolates in bone and joint infections is worrisome. MRSA associated cases of septic arthritis exhibit higher mortality, longer hospital stay, and higher treatment failure with poorer clinical outcomes as compared to cases caused by the sensitive strain i.e methicillin-sensitive S. aureus (MSSA).

In addition to this, equal or even greater damage is imposed by the exacerbated immune response mounted by the patient’s body in a futile attempt to eradicate the bacteria. The antibiotic therapy may not be sufficient enough to control the progression of damage to the joint involved thus, adding to higher mortality and disability rates despite the prompt and timely start of treatment. This situation implies that efforts and focus towards studying/understanding new strategies for improved management of sepsis arthritis is prudent and worth exploring.

The review article aims to give a complete insight into the new therapeutic approaches studied by workers lately in this field. To the best of our knowledge studies highlighting the novel therapeutic strategies against septic arthritis are limited in the literature, although articles on pathogenic mechanism and choice of antibiotics for therapy, current treatment algorithms followed have been discussed by workers in the past. The present study presents and discusses the new alternative approaches, their mechanism of action, proof of concept, and work done so far towards their clinical success. This will surely help to enlighten the researchers with comprehensive knowledge of the new interventions that can be used as an adjunct therapy along with conventional treatment protocol for improved success rates.

Intracellular Staphylococcus aureus in bone and joint infections: A mechanism of disease recurrence, inflammation, and bone and cartilage destruction

Bone and joint infections are devastating afflictions. Although medical interventions and advents have improved their care, bone and joint infections still portend dismal outcomes. Indeed, bone and joint infections are associated with extremely high mortality and morbidity rates and, generally, occur secondary to the aggressive pathogen Staphylococcus aureus. The consequences of bone and joint infections are further compounded by the fact that although they are aggressively treated, they frequently recur and result in massive bone and articular cartilage loss. Here, we review the literature and chronicle the fact that the fundamental cellular components of the musculoskeletal system can be internally infected with Staphylococcus aureus, which explains the ready recurrence of bone and joint infections even after extensive administration of antibiotic therapy and debridement and offer potential treatment solutions for further study. Moreover, we review the ramifications of intracellular infection and expound that the massive bone and articular cartilage loss is caused by the sustained proinflammatory state induced by infection and offer potential combination therapies for further study to protect bone and cartilage.

Platelet-Released Growth Factors Modulate the Secretion of Cytokines in Synoviocytes under Inflammatory Joint Disease

The etiology and pathogenesis of rheumatoid arthritis (RA) are marked by a complex interplay of various cell populations and is mediated by different signaling pathways. Traditionally, therapies have primarily focused on pain relief, reducing inflammation and the recovery of joint function. More recently, however, researchers have discussed the therapeutic efficacy of autologous platelet-rich plasma (PRP). The main objective of this work is to examine the influences of platelet-released growth factor (PRGF) on human synoviocytes under inflammatory conditions. Additionally, it is checked to which extend treatment with platelet concentrate influences the release of cytokines form synoviocytes. For this purpose, an in vitro RA model was created by stimulating the cells with the TNF-α. The release of cytokines was measured by ELISA. The cytokine gene expression was analyzed by real-time PCR. It has been observed that the stimulation concentration of 10 ng/ml TNF-α resulted in a significantly increased endogenous secretion and gene expression of IL-6 and TNF-α. The anti-inflammatory effect of PRGF could be confirmed through significant reduction of TNF-α and IL-1β. An induced inflammatory condition seems to cause PRGF to inhibit the release of proinflammatory cytokines. Further study is required to understand the exact effect mechanism of PRGF on synoviocytes.

Cathelicidin modulates synthesis of Toll-like Receptors (TLRs) 4 and 9 in colonic epithelium

Cathelicidin are innate antimicrobial peptides with broad immunomodulatory functions; however, their role in regulating intestinal defenses is not well characterized. This study aimed to investigate the role of cathelicidin modulating expression of Toll-like receptors (TLRs) 4 and 9 in colonic epithelium in response to bacterial patterns. We demonstrated herein that intestinal epithelial cells, when primed by bacterial lipopolysaccharide (LPS), responded to cathelicidin by increased transcription and protein synthesis of TLR4. This cathelicidin-induced response required the interaction of LPS-TLR4 and activation of MAPK signalling pathways. However, cathelicidin blocked TLR9 responses induced by TLR9 ligand CpG oligodeoxynucleotide (CpG ODN) in these colonic epithelial cells. Modulations of TLRs triggered by cathelicidin in intestinal epithelium occurred mainly in the apical compartment of intestinal cells. Activation of TLR4 by ligands in combination with cathelicidin promoted CXCL8 chemokine secretion and epithelial antimicrobial defenses against Escherichia coli. We concluded that cathelicidin selectively modulated synthesis of TLR4 and 9 in intestinal epithelium, but only when cells were exposed to virulence factors, mostly from apical surfaces. Enhanced TLR4 expression promoted by cathelicidin in intestinal epithelium may be crucial for controlling enteric infectious diseases.

Hepatocytes express the antimicrobial peptide HBD-2 after multiple trauma: an experimental study in human and mice

Background

Human-beta defensins (HBD) belong to the family of acute phase peptides and hold a broad antimicrobial spectrum that includes gram-positive and gram-negative bacteria. HBD are up-regulated after severe injuries but the source of posttraumatic HBD expression has not been focused on before.

In the current study we analysed the role of liver tissue in expression of HBD after multiple trauma in human and mice.

Methods

HBD-2 expression has been detected in plasma samples of 32 multiple trauma patients (ISS > 16) over 14 days after trauma by ELISA. To investigate major sources of HBD-2, its expression and regulation in plasma samples, polymorphonuclear neutrophils (PMN) and human tissue samples of liver and skin were analysed by ELISA. As liver samples of trauma patients are hard to obtain we tried to review findings in an established trauma model. Plasma samples and liver samples of 56 male C57BL/6 N-mice with a thorax trauma and a femur fracture were analysed by ELISA, real-time PCR and immunohistochemistry for murine beta defensin 4 (MBD-4) and compared with the expression of control group without trauma.

The induction of HBD-2 expression in cultured hepatocytes (Hep G2) was analysed after incubation with IL-6, supernatant of Staphylococcus aureus (SA) and Lipopolysaccharides (LPS). One possible signalling pathway was tested by blocking toll-like receptor 2 (TLR2) in hepatocytes.

Results

Compared to healthy control group, plasma of multiple traumatized patients and mice showed significantly higher defensin levels after trauma. Compared to skin cells, which are known for high beta defensin expression, liver tissue showed less HBD-2 expression, but higher HBD-2 expression compared to PMN. Immunhistochemical staining demonstrated upregulated MBD-4 in hepatocytes of traumatised mice. In HepG2 cells HBD-2 expression could be increased by stimulation with IL-6 and SA. Neutralization of HepG2 cells with αTLR2 showed reduced HBD-2 expression after stimulation with SA.

Conclusion

Plasma samples of multiple traumatized patients showed high expression of HBD-2, which may protect the severely injured patient from overwhelming bacterial infection. Our data support the hypothesis that liver is one possible source for HBD-2 in plasma while posttraumatic inflammatory response.

S100A12 and hBD2 correlate with the composition of the fecal microflora in ELBW infants and expansion of E. coli is associated with NEC

Objective. To describe the development of the gut microbiota in extremely low birth weight (ELBW) infants with and without necrotizing enterocolitis (NEC) between April 2008 and December 2009, fecal microflora was prospectively analyzed in fecal samples of all ELBW infants using real-time PCR assays. In addition, fecal inflammatory were measured. Results. Fecal microflora established early in ELBW infants and microbiota composition remained stable over the first 28 days of life except for the prevalence of C. difficile which decreased with decreasing antibiotic use. Infants who subsequently developed NEC had an increase of total bacterial count (9.8-fold) 24 h prior to clinical symptoms mainly due to the expansion of E. coli species (21.6-fold), whereas microbiota composition did not differ from healthy ELBW infants five days before onset of NEC. Importantly, S100A12 and hBD2 positively correlated with the total and E. coli bacterial CFU/g feces (r² 0.4 and 0.64, resp.). Conclusions. In summary, we found evidence for a disturbed homeostasis between the intestinal microbiome and host immunity in ELBW infants with NEC. Moreover, S100A12 and hBD2 correlate with the fecal microbiota thus linking the intestinal innate immune response to the bacterial colonization thus possibly providing a diagnostic tool in the future.

Effects of Low-Level Laser Therapy, 660 nm, in Experimental Septic Arthritis

The effectiveness of low-level laser therapy (LLLT) in the presence of an infectious process has not been well elucidated. The aim of the study was to evaluate the effects of LLLT in an experimental model of septic arthritis. Methods. Twenty-one Wistar rats were divided as follows: control group, no bacteria; placebo group, bacteria were inoculated; Treated group, bacteria were injected and treatment with LLLTwas performed. To assess nociception, a von Frey digital analgesimeter was applied. Synovial fluid was streaked to analyze bacterial growth. The standard strain of S. aureus was inoculated in the right knee. LLLT was performed with 660 nm, 2 J/cm², over 10 days. After treatment, the knees were fixed and processed for morphological analysis by light microscopy. Results. It was found that nociception increases in the right knee. There was a lack of results for the seeding of the synovial fluid. The morphological analysis showed slight recovery areas in the articular cartilage and synovia; however, there was the maintenance of the inflammatory infiltrate. Conclusion. The parameters used were not effective in the nociception reduction, even with the slight tissue recovery due to the maintenance of inflammatory infiltrate, but produced no change in the natural history of resolution of the infectious process.

Induction of β-Defensin Expression by Porphyromonas gingivalis-Infected Human Gingival Graft Transplanted in nu/nu Mouse Subdermis

It is important to understand the onset of periodontal disease in terms of bacterial infection and host factors. Host-bacteria interactions can be elicited in human cultured cells and animal models, but these models provide only limited biological information about human host reactions against bacterial attacks. Development of an in vivo model using human gingival tissue is needed. We established an in vivo model using nu/nu mice and evaluated host defense following bacterial infection in human gingiva. Human gingival samples were collected from periodontitis patients and transplanted in nu/nu mouse subdermis. After 2 weeks, human characteristics were confirmed by positive immunohistochemical reactions for human-specific markers. We used this model to investigate human β-defensin-2 (hBD-2), an antimicrobial peptide that contributes to initial defense against bacterial invasion. Using real-time polymerase chain reaction, in situ hybridization, and immunohistochemistry, we investigated whether hBD-2 expression was induced in human gingiva as a response to Porphyromonas gingivalis as a periodontal pathogen. Two hours after infection with bacteria, we detected increased expression of hBD-2 mRNA, which was localized in the epithelium of human gingiva. Using our in vivo model, we concluded that increased hBD-2 may play an important role in early defense from bacterial infection in human gingival epithelium.

CpG oligodeoxynucleotides induce the expression of the antimicrobial peptide cathelicidin in glial cells

During bacterial infections, antimicrobial peptides are synthesised as an important part of the innate immune system. However, expression and function in the central nervous system (CNS) need further investigations. The aim of this study was to examine the involvement of the pattern-recognition-receptor toll-like receptor 9 (TLR9) in the expression of the cathelin-related antimicrobial peptide (CRAMP) and to characterise the participating signal transduction pathways. In primary TLR9 deficient and wildtype mice astrocytes as well as microglia cells, the expression of CRAMP after treatment with the TLR9 agonist unmethylated cytosine-guanine oligodeoxynucleotide motifs (CpG-DNA) was examined in vitro. In vivo CRAMP expression after intraventricular infusion of CpG-DNA in TLR9 deficient and wildtype mice as well as in mice with pneumococcal meningitis localised in glial cells was determined. Furthermore, the regulation of different signal transduction pathways involved in CpG-DNA-induced CRAMP expression in glial cells was analysed. An in vitro and in vivo CpG-DNA-induced increase of CRAMP expression in astrocytes and microglia cells using real time RT-PCR and immunofluorescence was demonstrated. Different signal transduction pathways such as mitogen-activated protein kinases and inflammatory mediated pathways are involved in the expression of CRAMP in primary glial cells. Interestingly, TLR9-deficient glial cells showed a reduced but not completely abolished CRAMP mRNA expression and ERK1/2 phosphorylation in response to CpG-DNA treatment. On the other side in vivo, TLR9 deletion did not change CRAMP expression after bacterial infection. In conclusion, our results show that TLR9 can induce the expression of antimicrobial peptides such as CRAMP in response to bacterial DNA motifs in primary glial cells. Additional findings suggest also that CpG-DNA-induced effects are not only mediated by TLR9, but also mediated by other pattern recognition receptors.

Human β-defensin 2 expression in ELBW infants with severe necrotizing enterocolitis

BACKGROUND

The aim of this study was to analyze whether the mucosal innate immune response of extremely-low-birth-weight (ELBW) infants might play a role in the development of necrotizing enterocolitis (NEC).

METHODS

Between April 2008 and December 2009 antimicrobial peptides were prospectively measured in fecal samples of ELBW infants. In cases requiring abdominal surgery, full-thickness gut biopsies were analyzed for expression of human β-defensin 2 (hBD2), interleukin-8 (IL-8), villin, MD2, and Toll-like receptor 4 (TLR4).

RESULTS

Fecal hBD1 concentrations were consistently low in all patients, whereas hBD2 concentrations were high in meconium, particularly in clinical chorioamnionitis, and then dropped, followed by a steady increase after day 14. Infants with moderate NEC showed significantly increased fecal hBD2 concentrations before clinical symptoms, in contrast to infants developing severe NEC. Analysis of intestinal resection material obtained from patients with severe NEC revealed low hBD2 mRNA and protein levels, and increased expression of the inflammatory cytokine IL-8.

CONCLUSION

High hBD2 concentrations, reflecting strong intestinal immune responses, were associated with moderate courses of the disease. In severe NEC, low hBD2 expression was accompanied by low TLR4/MD2 expression, suggesting an inadequate response to luminal bacteria, possibly predisposing those infants to the development of NEC.

Nanostructured, self-assembling peptide K5 blocks TNF-α and PGE₂ production by suppression of the AP-1/p38 pathway

Nanostructured, self-assembling peptides hold promise for a variety of regenerative medical applications such as 3D cell culture systems, accelerated wound healing, and nerve repair. The aim of this study was to determine whether the self-assembling peptide K5 can be applied as a carrier of anti-inflammatory drugs. First, we examined whether the K5 self-assembling peptide itself can modulate various cellular inflammatory responses. We found that peptide K5 significantly suppressed the release of tumor-necrosis-factor- (TNF-) α and prostaglandin E₂ (PGE₂) from RAW264.7 cells and peritoneal macrophages stimulated by lipopolysaccharide (LPS). Similarly, there was inhibition of cyclooxygenase- (COX-) 2 mRNA expression assessed by real-time PCR, indicating that the inhibition is at the transcriptional level. In agreement with this finding, peptide K5 suppressed the translocation of the transcription factors activator protein (AP-1) and c-Jun and inhibited upstream inflammatory effectors including mitogen activated protein kinase (MAPK), p38, and mitogen-activated protein kinase kinase 3/6 (MKK 3/6). Whether this peptide exerts its effects via a transmembrane or cytoplasmic receptor is not clear. However, our data strongly suggest that the nanostructured, self-assembling peptide K5 may possess significant anti-inflammatory activity via suppression of the p38/AP-1 pathway.

Toll-like receptor--a potent driving force behind rheumatoid arthritis

Toll like receptor (TLR), one of the key functions of innate immune system, can recognize not only exogenous pathogen-associated molecular patterns, namely PAMPs, but also endogenous molecules created upon tissue injury, sterile inflammation and degeneration. Endogenous TLR ligands are called as damage-associated molecular patters (DAMPs), including endogenous molecules released by activated and necrotic cells, and extracellular matrix molecules. DAMPs are also known as alarmins. TLR research has brought about new insights in the rheumatic diseases. Previous reports suggest that TLRs and the signal pathways intensively contribute to the pathogenesis of rheumatoid arthritis (RA) and other arthritic conditions with interaction of various TLR ligands. Accumulated knowledge of TLR system is summarized to overlook TLRs and the signaling pathway in arthritis conditions, with special reference to RA.

What's New in the Management of Bacterial Septic Arthritis?

Septic arthritis is a common rheumatological emergency requiring prompt diagnosis and treatment, since delays in management can lead to high morbidity and mortality. In this review article, we discuss the epidemiology and recent advances in knowledge of the pathogenesis of septic arthritis, with a special emphasis on various bacterial and host factors involved in mediating the inflammatory process and the potential for targeted therapy to modulate the immune response. Recent advances in laboratory and imaging techniques are reviewed along with treatment and potential new therapies.

Protective role of IL-1β against post-arthroplasty Staphylococcus aureus infection

MyD88 is an adapter molecule that is used by both IL-1R and TLR family members to initiate downstream signaling and promote immune responses. Given that IL-1β is induced after Staphylococcus aureus infections and TLR2 is activated by S. aureus lipopeptides, we hypothesized that IL-1β and TLR2 contribute to MyD88-dependent protective immune responses against post-arthroplasty S. aureus infections. To test this hypothesis, we used a mouse model of a post-arthroplasty S. aureus infection to compare the bacterial burden, biofilm formation and neutrophil recruitment in IL-1β-deficient, TLR2-deficient and wild-type (wt) mice. By using in vivo bioluminescence imaging, we found that the bacterial burden in IL-1β-deficient mice was 26-fold higher at 1 day after infection and remained 3- to 10-fold greater than wt mice through day 42. In contrast, the bacterial burden in TLR2-deficient mice did not differ from wt mice. In addition, implants harvested from IL-1β-deficient mice had more biofilm formation and 14-fold higher adherent bacteria compared with those from wt mice. Finally, IL-1β-deficient mice had ∼50% decreased neutrophil recruitment to the infected postoperative joints than wt mice. Taken together, these findings suggest a mechanism by which IL-1β induces neutrophil recruitment to help control the bacterial burden and the ensuing biofilm formation in a post-surgical joint.

Platelets display potent antimicrobial activity and release human beta-defensin 2

Platelet-rich plasma (PRP) is a potent agent that improves soft tissue and bone healing. By the release of growth factors and cytokines, PRP is believed to locally boost physiologic healing processes. Recently, antimicrobial activity of PRP has been demonstrated against S. aureus strains. Major scientific effort is being put into the understanding and prevention of infections i.e. by delivery of antimicrobial substances. In previous studies we showed the ideal antibacterial activity-profile of the human beta-defensin 2 (hBD-2) for orthopaedic infections and therefore hypothesized that hBD-2 may be the effector of antimicrobial platelet action. Platelet concentrates were produced from human platelet phresis obtained from a hospital blood bank. They were screened by immunohistochemistry, Western Blot and ELISA for the human beta defensin-2. In vitro susceptibility to PRP was investigated by a standard disc diffusion test with or without pre-incubation of PRP with anti-hBD-2 antibody. SPSS statistical software was used for statistical analysis. PRP contains hBD-2 470 pg/10(9) platelets or 1786 pg/ml, respectively, (ELISA), which was confirmed by immunohistochemistry and Western Blot. In antimicrobial testing, PRP demonstrates effective inhibition of E. coli, B. megaterium, P. aeruginosa, E. faecalis and P. mirabilis. With this study we confirm the previously reported antimicrobial action of platelet concentrates i.e. PRP. In opposition to previously reported effects against gram positive bacteria our study focuses on gram negative and less common gram positive bacteria that do frequently cause clinical complications. We provide a possible molecular mechanism at least for E. coli and P. mirabilis for this effect by the detection of an antimicrobial peptide (hBD-2). This study may advocate the clinical use of PRP by highlighting a new aspect of platelet action.

Administration of nonviral gene vector encoding rat beta-defensin-2 ameliorates chronic Pseudomonas aeruginosa lung infection in rats

BACKGROUND

Beta-defensin-2 (BD-2) plays an important role in host defense against pathogenic microbe challenge by its direct antimicrobial activity and immunomodulatory functions. The present study aimed to determine whether genetic up-regulation of rat BD-2 (rBD-2) could ameliorate chronic Pseudomonas aeruginosa lung infection in rats.

METHODS

Plasmid-encoding rBD-2 was delivered to lungs in vivo using linear polyethylenimine at 48 h before challenging with seaweed alginate beads containing P. aeruginosa. Macroscopic and histopathological changes of the lungs, bacterial loads, inflammatory infiltration, and the levels of cytokines/chemokines [interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha, kertinocyte-derived chemokine (KC), macrophage inflammatory protein-2 (MIP-2)] were measured at 3 and 7 days post-infection (p.i.).

RESULTS

The overexpression of rBD-2 resulted in a significant increase in animal survival rate (at 3 days p.i.), a significant decrease in bacterial loads in the lungs (at 3 and 7 days p.i.), and significantly milder lung pathology. In addition, the overexpression of rBD-2 led to increased infiltration of polymorphonuclear neutrophils (PMN), and elevated protein expression of cytokines/chemokines (IL-1beta, TNF-alpha, KC and MIP-2) at the early stage of infection (at 3 days p.i.), at the same time as being dramatically decreased at the later stage of infection (at 7 days p.i.).

CONCLUSIONS

Genetic up-regulation of rBD-2 increased animal survival rate, and reduced bacterial loads in lungs after bacterial infection. The overexpression of rBD-2 also modulated the production of several cytokines/chemokines and increased PMN recruitment at the early stage of infection. Our findings indicate that the enhancement of BD-2 may be an efficacious intervention for chronic P. aeruginosa lung infection.

Defensins attenuate cytokine responses yet enhance antibody responses to Porphyromonas gingivalis adhesins in mice

AIM

Our aim is to assess the ability of human neutrophil peptide alpha-defensins (HNPs) and human beta-defensins (HBDs) to attenuate proinflammatory cytokine responses and enhance antibody responses to recombinant hemagglutinin B (rHagB) or recombinant fimbrillin A (rFimA) from Porphyromonas gingivalis 381 in mice.

MATERIALS & METHODS

In the first study, C57BL/6 mice were given 10 microg rHagB or rFimA without and with 1 microg HNP1, HNP2, HBD1, HBD2 or HBD3. At 24 h, mice were euthanized and cytokine concentrations were determined in nasal wash fluid (NWF), bronchoalveolar lavage fluids, saliva and serum. In the second study, C57BL/6 mice were given 10 microg rHagB or rFimA without and with 1 microg HNPs or HBDs similarly on days 0, 7 and 14. At 21 days, mice were euthanized and rHagB- and rFimA-specific antibody responses were determined in NWF, bronchoalveolar lavage fluids, saliva and serum.

RESULTS

Mice given rHagB + HNP2, rHagB + HBD1 and rHagB + HBD3 produced significantly lower (p < 0.05) IL-6 responses than mice given rHagB alone. Mice given rHagB + HNP1, rHagB + HNP2, rHagB + HBD1 and rHagB + HBD3 produced significantly lower (p < 0.05) keratinocyte-derived chemokine responses than mice given rHagB alone. Mice given rFimA produced very low levels of IL-6 and only moderate levels of keratinocyte-derived chemokine in NWF that were not attenuated by prior incubation of rFimA with any defensin. Mice given rHagB + HNP1 produced a significantly higher (p < 0.05) serum IgG antibody response than mice given rHagB alone and mice given rFimA + HNP2 produced a higher, but not significant, antibody response.

CONCLUSION

The ability of HNPs and HBDs to attenuate proinflammatory cytokine responses in murine NWF and enhance IgG antibody responses in serum was dependent upon both the defensin and antigen of P. gingivalis.