Neutrophils Enhance Their Own Influx to Sites of Bacterial Infection via Endosomal TLR-Dependent Cxcl2 Production.

The influx of neutrophils to infection sites is a fundamental step in host defenses against the frequent human pathogen group B Streptococcus (GBS) and other extracellular bacteria. Using a mouse model of GBS-induced peritonitis, we show in this study that the chemokines Cxcl1 and Cxcl2 play distinctive roles in enhancing the recruitment and the antibacterial activities of neutrophils in a manner that is linked to differences in the cellular sources of these mediators. Cell depletion experiments demonstrated that neutrophils make a significant contribution to the in vivo production of Cxcl2 but not Cxcl1. In vitro, neutrophils responded weakly to LPS but released high levels of Cxcl2 after stimulation with GBS or other bacteria. Neutrophil-derived Cxcl2 acted in an autocrinous manner to increase its own production and to enhance antibacterial activities, including the release of oxygen radicals. In both neutrophils and macrophages, the production of Cxcl1/2 largely required the presence of functional UNC93B1, a chaperone protein involved in signaling by endosomal TLRs. Moreover, the phenotype of UNC93B1-defective phagocytes could be recapitulated by the simultaneous absence of TLR7, 9, and 13 but not by the absence of individual TLRs. Collectively, our data show that neutrophils recognize Gram-positive and Gram-negative bacteria by means of multiple phagosomal TLRs, resulting in de novo synthesis of Cxcl2, amplification of neutrophil recruitment, and potentiation of their antibacterial activities. These data may be useful to devise alternative therapeutic strategies aimed at enhancing the recruitment and the functional activities of polymorphonuclear leukocytes during infections caused by antibiotic-resistant bacteria.

Role of Paricalcitol in Modulating the Immune Response in Patients with Renal Disease.

Introduction. The aim was to highlight the existence of a relationship between vitamin D deficiency, chronic inflammation, and proteinuria, by measuring neutrophil gelatinase associated lipocalin (NGAL) and common inflammatory markers after administration of paricalcitol, a vitamin D analog, in vivo and in vitro. Methods. 40 patients with end-stage chronic kidney disease (CKD) and secondary hyperparathyroidism and 40 healthy subjects were enrolled. Serum calcium, phosphorus, 25(OH)-vitamin D, parathyroid hormone (PTH), erythrocyte sedimentation rate, high-sensitivity C-reactive protein, interleukin- (IL-) 17, IL-6, IL-1ß, interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), plasmatic and urinary NGAL, and 24 h albuminuria and proteinuria were measured before and 24 h after an intravenous bolus of paricalcitol (5 mcg). Human peripheral blood mononuclear cells were isolated and stimulated with phytohaemagglutinin. NGAL, IL-1ß, IL-17, IL-6, TNF-α, and IFN-γ were measured in the culture medium and in the 24 h urine collection. Results. 25(OH)-vitamin D was lower in CKD than in controls (p < 0.0001), while inflammatory markers were higher in CKD group (p < 0.0001). In vivo and in vitro studies showed a downregulation of NGAL, IL-17, IL-6, IL-1ß, TNF-α, and IFN-γ after paricalcitol administration (p < 0.0001). Conclusions. 25(OH)-vitamin D regulates immune and inflammatory processes. Further studies are needed to confirm these data in order to improve the treatment of CKD patients.

Both IL-1ß and TNF-α regulate NGAL expression in polymorphonuclear granulocytes of chronic hemodialysis patients.

BACKGROUND: NGAL is involved in modulation of the inflammatory response and is found in the sera of uremic patients. We investigated whether hemodiafiltration (HDF) could influence the ability of polymorphonuclear granulocytes (PMGs) to release NGAL. The involvement of interleukin- (IL-)1ß and tumor necrosis factor- (TNF-)α on NGAL release was evaluated. METHODS: We studied end-stage renal disease (ESRD) patients at the start of dialysis (Pre-HDF) and at the end of treatment (Post-HDF) and 18 healthy subjects (HSs). Peripheral venous blood was taken from HDF patients at the start of dialysis and at the end of treatment. RESULTS: PMGs obtained from ESRD patients were hyporesponsive to LPS treatment, with respect to PMG from HS. IL-1ß and TNF-α produced by PMG from post-HDF patients were higher than those obtained by PMG from pre-HDF. Neutralization of IL-1ß, but not of TNF-α, determined a clear-cut production of NGAL in PMG from healthy donors. On the contrary, specific induction of NGAL in PMG from uremic patients was dependent on the presence in supernatants of IL-1ß and TNF-α. CONCLUSION: Our data demonstrate that in PMG from healthy subjects, NGAL production was supported solely by IL-1ß, whereas in PMG from HDF patients, NGAL production was supported by IL-1ß, TNF-α.

An exopolysaccharide produced by Geobacillus thermodenitrificans strain B3-72: antiviral activity on immunocompetent cells.

The immunomodulatory and antiviral effects of an extracellular polysaccharide (EPS-2), produced by a strain of Geobacillus thermodenitrificans isolated from a shallow marine vent of Vulcano Island (Italy), were evaluated. In the present study, we show for the first time that EPS-2 treatment hinder HSV-2 replication in human peripheral blood mononuclear cells (PBMC) but not in WISH cells. In fact, high levels of IFN-alpha, IL-12, IFN-gamma, TNF-alpha, IL-18 were detected in supernatants of EPS-2 treated PBMC. Moreover, this effect was dose-dependent. Taken together, our results confirm that the immunological disorders determined by HSV-2 could be partially restored by treatment with EPS-2.

Facile biocatalytic access to 9-fluorenylmethyl polyglycosides: evaluation of antiviral activity on immunocompetent cells.

The biological activities of a series of mono- and oligosaccharides (beta-xylosides and alpha-glucosides) of 9-fluorenylmethanol were investigated together with mono-beta-galactoside and beta-glucoside of this aglycone, produced by biocatalytic routes. By using marine glycoside hydrolases and inexpensive donors such as maltose or xylan, access to mono-alpha-glucoside or mono-beta-xyloside of 9-fluorenylmethanol was obtained. Additionally, interesting polyglycoside derivatives were isolated. Biological testing indicated that in vitro treatment with these carbohydrate derivatives may influence the balance of cytokines in the environment of human peripheral blood mononuclear cells (PBMC), restricting the harmful effect of herpes simplex type 2 replication. In fact, these carbohydrate derivatives tested in WISH cells did not show any significant antiviral activity.

Impaired antiviral activity of monocytes from patients on hemodiafiltration.

BACKGROUND: The aim of our study was to determine whether intermittent hemodiafiltration (HDF) leads to an alteration in monocyte antiviral activity as well as in the in vitro release of cytokines such as interleukin-12 (IL-12), tumor necrosis factor-alpha (TNF-alpha) and interferon-alpha (IFN-alpha) by the same cells. METHODS: We enrolled 25 patients undergoing HDF for 3.5-4 hours 3 times a week (12 men, 13 women; mean age 58 +/- 6.7 years) and 25 healthy donors (ND) (12 men, 13 women; mean age 57 +/- 8 years). Monocytes from peripheral blood mononuclear cells were isolated with a Monocyte Isolation Kit II. Monocytic cells were infected with herpes simplex virus type 2 (HSV-2). Cytokines were assayed in supernatants. RESULTS: The in vitro antiviral activity of monocytes from HDF patients was significantly impaired with respect to ND. Furthermore, monocytes from post-HDF patients were more prone to viral infection. Lipopolysaccharide (LPS) stimulation induced significant viral inhibition only in monocytes from NDs (p<0.05). The cytokine pattern (TNF-alpha, IFN-alpha and IL-12) in monocytes stimulated with LPS was markedly inhibited in HDF patients compared with ND (p<0.05). A basal production of TNF-alpha was found in monocytes from pre-HDF and post-HDF patients. No IFN-alpha production was found in LPS-stimulated and HSV-2-infected monocytes from pre-HDF and post-HDF patients. IL-12 production appeared significantly decreased after HDF in all experimental conditions (p<0.05). CONCLUSIONS: The significant increase of viral replication in monocytes from HDF patients compared with healthy donors could be related to a significant reduction of cytokine production. Moreover, the dialytic session influenced the intrinsic antiviral activity of monocytes, favoring viral replication.

Antiviral and immunoregulatory effect of a novel exopolysaccharide from a marine thermotolerant Bacillus licheniformis.

EPS-1 is a novel extracellular polysaccharide produced by a strain of thermotolerant Bacillus licheniformis, isolated from a shallow marine hot spring of Vulcano Island (Italy). In this paper, antiviral and immunomodulatory effects of EPS-1 were evaluated. It was found that EPS-1 treatment impaired HSV-2 replication in human peripheral blood mononuclear cells (PBMC) but not in WISH cells. Since several cytokines modulate the immune response to viruses, Th1- and Th2-type cytokines were assayed in supernatants of PBMC in different experimental conditions. EPS-1 induced IL-12, IFN-gamma, IFN-alpha, TNF-alpha and IL-18, but not IL-4. Thus, the antiviral effect of EPS-1 on PBMC seems to be related to the pattern of cytokines induced.