A holistic evaluation of patients with chronic Hepatitis D virus (HDV) infection enrolled in the Italian PITER-B and delta cohort.

BACKGROUND AND AIMS: We aimed to characterize the epidemiologic and comorbidities profiles of patients with chronic Hepatitis D (CHD) followed in clinical practice in Italy and explored their interferon (IFN) eligibility. METHODS: This was a cross-sectional study of the PITER cohort consisting of consecutive HBsAg-positive patients from 59 centers over the period 2019-2023. Multivariable analysis was performed by logistic regression model. RESULTS: Of 5492 HBsAg-positive enrolled patients, 4152 (75.6%) were screened for HDV, 422 (10.2%) were anti-HDV positive. Compared with HBsAg mono-infected, anti-HDV positive patients were more often younger, non-Italians, with a history of drug use, had elevated alanine transaminase (ALT), cirrhosis, or hepatocellular carcinoma (HCC). Compared with Italians, anti-HDV positive non-Italians were younger (42.2% age ≤ 40 years vs. 2.1%; P < 0.001), more often females (males 43.0% vs. 68.6%; P < 0.001) with less frequent cirrhosis and HCC. HDV-RNA was detected in 63.2% of anti-HDV-positive patients, who were more likely to have elevated ALT, cirrhosis, and HCC. Extrahepatic comorbidities were present in 47.4% of anti-HDV positive patients and could affect the eligibility of IFN-containing therapies in at least 53.0% of patients in care. CONCLUSIONS: CHD affects young, foreign-born patients and older Italians, of whom two-thirds had cirrhosis or HCC. Comorbidities were frequent in both Italians and non-Italians and impacted eligibility for IFN.

Reduction of the Risk of Hepatocellular Carcinoma over Time Using Direct-Acting Antivirals: A Propensity Score Analysis of a Real-Life Cohort (PITER HCV).

The treatment of hepatitis C virus (HCV) with direct-acting antivirals (DAA) leads to high sustained virological response (SVR) rates, but hepatocellular carcinoma (HCC) risk persists in people with advanced liver disease even after SVR. We weighted the HCC risk in people with cirrhosis achieving HCV eradication through DAA treatment and compared it with untreated participants in the multicenter prospective Italian Platform for the Study of Viral Hepatitis Therapies (PITER) cohort. Propensity matching with inverse probability weighting was used to compare DAA-treated and untreated HCV-infected participants with liver cirrhosis. Kaplan-Meier analysis and competing risk regression analysis were performed. Within the first 36 months, 30 de novo HCC cases occurred in the untreated group (n = 307), with a weighted incidence rate of 0.34% (95%CI: 0.23-0.52%), compared to 63 cases among SVR patients (n = 1111), with an incidence rate of 0.20% (95%CI: 0.16-0.26%). The 12-, 24-, and 36-month HCC weighted cumulative incidence rates were 6.7%, 8.4%, and 10.0% in untreated cases and 2.3%, 4.5%, and 7.0% in the SVR group. Considering death or liver transplantation as competing events, the untreated group showed a 64% higher risk of HCC incidence compared to SVR patients (SubHR 1.64, 95%CI: 1.02-2.62). Other variables independently associated with the HCC occurrence were male sex, increasing age, current alcohol use, HCV genotype 3, platelet count ≤ 120,000/µL, and albumin ≤ 3.5 g/dL. In real-life practice, the high efficacy of DAA in achieving SVR is translated into high effectiveness in reducing the HCC incidence risk.

Predicting de-novo portal vein thrombosis after HCV eradication: A long-term competing risk analysis in the ongoing PITER cohort.

BACKGROUND & AIMS: Sustained virological response (SVR) by direct-acting antivirals (DAAs) may reverse the hypercoagulable state of HCV cirrhosis and the portal vein thrombosis (PVT) risk. We evaluated the incidence and predictive factors of de novo, non-tumoral PVT in patients with cirrhosis after HCV eradication. METHODS: Patients with HCV-related cirrhosis, consecutively enrolled in the multi-center ongoing PITER cohort, who achieved the SVR using DAAs, were prospectively evaluated. Kaplan-Meier and competing risk regression analyses were performed. RESULTS: During a median time of 38.3 months (IQR: 25.1-48.7 months) after the end of treatment (EOT), among 1609 SVR patients, 32 (2.0%) developed de novo PVT. A platelet count ≤120,000/µL, albumin levels ≤3.5 mg/dL, bilirubin >1.1 mg/dL, a previous liver decompensation, ALBI, Baveno, FIB-4, and RESIST scores were significantly different (p < 0.001), among patients who developed PVT versus those who did not. Considering death and liver transplantation as competing risk events, esophageal varices (subHR: 10.40; CI 95% 4.33-24.99) and pre-treatment ALBI grade ≥2 (subHR: 4.32; CI 95% 1.36-13.74) were independent predictors of PVT. After HCV eradication, a significant variation in PLT count, albumin, and bilirubin (p < 0.001) versus pre-treatment values was observed in patients who did not develop PVT, whereas no significant differences were observed in those who developed PVT (p > 0.05). After the EOT, esophageal varices and ALBI grade ≥2, remained associated with de novo PVT (subHR: 9.32; CI 95% 3.16-27.53 and subHR: 5.50; CI 95% 1.67-18.13, respectively). CONCLUSIONS: In patients with HCV-related cirrhosis, a more advanced liver disease and significant portal hypertension are independently associated with the de novo PVT risk after SVR.

Profiling the risk of hepatocellular carcinoma after long-term HCV eradication in patients with liver cirrhosis in the PITER cohort.

BACKGROUND AND AIMS: Severe liver disease markers assessed before HCV eradication are acknowledged to usually improve after the SVR. We prospectively evaluated, in the PITER cohort, the long-term HCC risk profile based on predictors monitored after HCV eradication by direct-acting antivirals in patients with cirrhosis. METHODS: HCC occurrence was evaluated by Kaplan-Meier analysis. Cox regression analysis identified the post-treatment variables associated with de-novo HCC; their predictive power was presented in a nomogram. RESULTS: After the end of therapy (median follow-up:28.47 months), among 2064 SVR patients, 119 (5.8%) developed de-novo HCC. The HCC incidence was 1.90%, 4.21%, 6.47% at 12-, 24- and 36-months from end-of-therapy, respectively (incidence rate 2.45/100 person-years). Age, genotype 3, diabetes, platelets (PLT)≤120,000/µl and albumin ≤3.5g/dl levels were identified as pre-treatment HCC independent predictors. Adjusting for age, the post-treatment PLT≤120,000/µl (AdjHR 1.92; 95%CI:1.06-3.45) and albumin≤3.5g/dl (AdjHR 4.38; 95%CI 2.48-7.75) values were independently associated with HCC occurrence. Two different risk profiles were identified by combining long-term post-therapy evaluation of PLT ≤ vs. >120,000/µl and albumin ≤ vs. >3.5g/dl showing a significant different HCC incidence rate of 1.35 vs. 3.77/100 p-y, respectively. CONCLUSIONS: The nomogram score based on age, PLT and albumin levels after SVR showed an accurate prediction capability and may support the customizing management for early HCC detection.

Obesity and Dysmetabolic Factors among Deceased COVID-19 Adults under 65 Years of Age in Italy: A Retrospective Case-Control Study.

BACKGROUND: Italy has witnessed high levels of COVID-19 deaths, mainly at the elderly age. We assessed the comorbidity and the biochemical profiles of consecutive patients ≤65 years of age to identify a potential risk profile for death. METHODS: We retrospectively analyzed clinical data from consecutive hospitalized-for-COVID-19 patients ≤65 years, who were died (593 patients) or discharged (912 patients) during February-December 2020. Multivariate logistic regression identified the mortality risk factors. RESULTS: Overweight (adjusted odds ratio (adjOR) 5.53, 95% CI 2.07-14.76), obesity (adjOR 8.58, CI 3.30-22.29), dyslipidemia (adjOR 10.02, 95% CI 1.06-94.22), heart disease (adjOR 17.68, 95% CI 3.80-82.18), cancer (adjOR 13.28, 95% CI 4.25-41.51) and male sex (adjOR 5.24, 95% CI 2.30-11.94) were associated with death risk in the youngest population. In the older population (46-65 years of age), the overweight and obesity were also associated with the death risk, however at a lower extent: the adjORs varyied from 1.49 to 2.36 for overweight patients and from 3.00 to 4.07 for obese patients. Diabetes was independently associated with death only in these older patients. CONCLUSION: Overweight, obesity and dyslipidemia had a pivotal role in increasing young individuals' death risk. Their presence should be carefully evaluated for prevention and/or prompt management of SARS-CoV2 infection in such high-risk patients to avoid the worst outcomes.

Advanced liver disease outcomes after hepatitis C eradication by human immunodeficiency virus infection in PITER cohort.

BACKGROUND: Liver disease progression after Hepatitis C Virus (HCV) eradication following direct-acting antiviral (DAA) treatment in the real-life setting according to Human Immunodeficiency Virus (HIV) coinfection was evaluated. METHODS: Patients consecutively enrolled in PITER between April 2014 and June 2019 and with at least 12-weeks follow-up following treatment were analysed. Cox regression analysis were used to evaluate HIV coinfection and factors independently associated with liver disease outcomes following viral eradication in DAA treated patients with pre-treatment liver cirrhosis. RESULTS: 93 HIV/HCV coinfected and 1109 HCV monoinfected patients were evaluated during a median follow-up of 26.7 (range 6-44.6) and 24.6 (range 6.8-47.3) months, respectively. No difference in the cumulative HCC incidence and hepatic decompensation was observed between coinfected and monoinfected patients. Age (Hazard Ratio [HR] = 1.08; 95% CI 1.04-1.13), male sex (HR = 2.76; 95% CI 1.28-5.96), lower albumin levels (HR = 3.94; 95% CI 1.81-8.58), genotype 3 (HR = 5.05; 95% CI 1.75-14.57) and serum anti-HBc positivity (HR = 1.99, 95% CI 1.01-3.95) were independently associated with HCC incidence. Older age (HR = 1.03; 95% CI 1.00-1.07), male sex (HR = 2.13; 95% CI 1.06-4.26) and lower albumin levels (HR = 3.75; 95% CI 1.89-7.46) were independently associated with the appearance of a decompensating event after viral eradication. CONCLUSION: Different demographic, clinical and genotype distribution between HIV coinfected vs those monoinfected, was observed in a representative cohort of HCV infected patients in Italy. Once liver cirrhosis is established the disease progression is decreased, but still persists regardless of viral eradication in both coinfected and monoinfected patients. In patients with cirrhosis, HIV coinfection was not associated with a higher probability of liver complications, after viral eradication.

Exogenous HIV-1 Nef upsets the IFN-γ-induced impairment of human intestinal epithelial integrity.

BACKGROUND: The mucosal tissues play a central role in the transmission of HIV-1 infection as well as in the pathogenesis of AIDS. Despite several clinical studies reported intestinal dysfunction during HIV infection, the mechanisms underlying HIV-induced impairments of mucosal epithelial barrier are still unclear. It has been postulated that HIV-1 alters enterocytic function and HIV-1 proteins have been detected in several cell types of the intestinal mucosa. In the present study, we analyzed the effect of the accessory HIV-1 Nef protein on human epithelial cell line. METHODOLOGY/PRINCIPAL FINDINGS: We used unstimulated or IFN-γ-stimulated Caco-2 cells, as a model for homeostatic and inflamed gastrointestinal tracts, respectively. We investigated the effect of exogenous recombinant Nef on monolayer integrity analyzing its uptake, transepithelial electrical resistance, permeability to FITC-dextran and the expression of tight junction proteins. Moreover, we measured the induction of proinflammatory mediators. Exogenous Nef was taken up by Caco-2 cells, increased intestinal epithelial permeability and upset the IFN-γ-induced reduction of transepithelial resistance, interfering with tight junction protein expression. Moreover, Nef inhibited IFN-γ-induced apoptosis and up-regulated TNF-α, IL-6 and MIP-3α production by Caco-2 cells while down-regulated IL-10 production. The simultaneous exposure of Caco-2 cells to Nef and IFN-γ did not affect cytokine secretion respect to untreated cells. Finally, we found that Nef counteracted the IFN-γ induced arachidonic acid cascade. CONCLUSION/SIGNIFICANCE: Our findings suggest that exogenous Nef, perturbing the IFN-γ-induced impairment of intestinal epithelial cells, could prolong cell survival, thus allowing for accumulation of viral particles. Our results may improve the understanding of AIDS pathogenesis, supporting the discovery of new therapeutic interventions.

Effects of HIV-1 Nef on virus co-receptor expression and cytokine release in human bladder, laryngeal, and intestinal epithelial cell lines.

HIV infections are mainly acquired by mucosal transmission, through oral, rectal, or genital mucosa. Epithelial cells (EC) are the first cells encountered by HIV during infection through sexual transmission and breastfeeding. EC express several receptors critical for both primary HIV infection and secondary transmission. The regulation of co-receptor expression correlates with changes in susceptibility to infection by HIV-1 strains with different tropism. Moreover, inflammatory responses at mucosal surfaces after HIV-1 transmission may influence disease outcome. In the present study, we analyzed the effect of the accessory HIV-1 Nef protein on mucosal EC, using unstimulated or IFN-γ-stimulated HEp-2, T24, and Caco2 cell lines as models for homeostatic or inflamed mucosal tracts. We found that Nef significantly upregulated the expression of CXCR4 on the Caco-2 cell surface and the expression of galactosylceramide on the T24 cell surface. In addition, Nef significantly upregulated IL-6 production by T24 and Caco-2 cells, and TNF-α release by all three cell lines analyzed. Notably, Nef abrogated the IFN-γ-induced modulation of co-receptor expression and cytokine secretion. Our findings suggest that Nef differently regulates co-receptor expression and cytokine secretion at the epithelial level, depending on the anatomical derivation of the cells and the inflammatory status.

Docosahexaenoic acid modulates in vitro the inflammation of celiac disease in intestinal epithelial cells via the inhibition of cPLA2.

BACKGROUND & AIMS: The cytosolic phospolypase A(2) (cPLA(2)) - dependent release of arachidonic acid (AA) from the intra-epithelial lymphocytes plays a pivotal role in arming lymphocytes to cytolysis in the immune response of celiac disease. However, little is known about the role of enterocytes in releasing AA. Docosahexaenoic acid (DHA) is a long chain polyunsaturated fatty acid that counteracts many of the proinflammatory effect of AA. The aims of the present work were to evaluate if: 1) intestinal epithelial cells have a role in the celiac inflammation, releasing AA, and 2) if DHA is able to modulate the celiac inflammation, down-regulating the release of AA. METHODS: A human intestinal epithelial cell line (Caco-2) was exposed to gliadin peptides (PT-gl) (500 µg/ml) and DHA (2 µg/ml), both alone and simultaneously up to 24 h. RESULTS: The exposure of those cells to PT-gl alone resulted in an increased AA release, cycloxygenase-2 expression, cPLA(2) activity and prostaglandin E(2) and interleukin-8 release in culture medium, whereas the simultaneous exposure of the cells to DHA and PT-gl prevented the above-mentioned increases. CONCLUSIONS: These results suggest that intestinal epithelial cells sustain the celiac inflammation, releasing AA when stimulated with gliadin and that DHA inhibits the AA release by these cells.

Immunoregulatory effects of HIV-1 Nef protein.

During HIV infection, the perturbation of the adaptive and innate immune responses contributes to the progressive immunosuppression leading to an increased susceptibility to opportunistic infections and neoplastic diseases. Several impairments observed in HIV-infected patients include a gradual loss of CD4(+) T cells, CD8(+) T cell dysfunction, and a decreased number and function of natural killer (NK) cells. Moreover, a functional impairment and variation in the number of DC and B cells were observed during HIV infection. HIV-1 codes for proteins, including the accessory Nef proteins, that interacting with immune cells may contribute to AIDS pathogenesis. Here, we review the recent progress on the immunomodulatory effect of the accessory Nef protein and its role in the pathogenesis of HIV-1 infection. (c) 2009 International Union of Biochemistry and Molecular Biology, Inc.

Leptin exerts an anti-apoptotic effect on human dendritic cells via the PI3K-Akt signaling pathway.

Leptin is an adipocyte-derived hormone/cytokine that modulates immune responses. It induces functional and morphological changes in human dendritic cells (DCs), licensing them towards Th1 priming and promoting DC survival. Here we found that leptin protects DCs from spontaneous, UVB and H(2)O(2)-induced apoptosis, by triggering the activation of nuclear factor-kappa B (NF-kappaB) and a parallel up-regulation of bcl-2 and bcl-XL gene expression and Akt activation. We found that leptin activates the PI3K-Akt signaling pathway as demonstrated by the suppression of the effect of leptin on DC survival by wortmannin and API-2, which suppress the leptin-induced activation of Akt, NF-kappaB, bcl-2, bcl-XL and protection from apoptosis. These results provide insights on the immunoregulatory function of leptin, supporting a potential application in immunotherapeutic approaches.

Cytotoxic necrotizing factor 1 prevents apoptosis via the Akt/IkappaB kinase pathway: role of nuclear factor-kappaB and Bcl-2.

Cytotoxic necrotizing factor 1 (CNF1) is a protein toxin produced by some pathogenic strains of Escherichia coli that specifically activates Rho, Rac, and Cdc42 GTPases. We previously reported that this toxin prevents the ultraviolet-B-induced apoptosis in epithelial cells, with a mechanism that remained to be defined. In this work, we show that the proteasomal degradation of the Rho GTPase is necessary to achieve cell death protection, because inhibition of Rho degradation abolishes the prosurvival activity of CNF1. We hypothesize that Rho inactivation allows the activity of Rac to become dominant. This in turn leads to stimulation of the phosphoinositide 3-kinase/Akt/IkappaB kinase/nuclear factor-kappaB prosurvival pathway and to a remarkable modification in the architecture of the mitochondrial network, mainly consisting in the appearance of elongated and interconnected mitochondria. Importantly, we found that Bcl-2 silencing reduces the ability of CNF1 to protect cells against apoptosis and that it also prevents the CNF1-induced mitochondrial changes. It is worth noting that the ability of a bacterial toxin to induce such a remodeling of the mitochondrial network is herein reported for the first time. The possible pathophysiological relevance of this finding is discussed.

HIV-1 Nef impairs the dynamic of DC/NK crosstalk: different outcome of CD56(dim) and CD56(bright) NK cell subsets.

Dendritic cells (DCs) and natural killer (NK) cells are essential components of the innate immunity and play a critical role in the first phase of host defense against infection. Interactions between DCs and NK cells have been demonstrated in a variety of settings, with evidence emerging of complex bidirectional crosstalk between the two cell types. The accessory HIV-1 Nef protein is a crucial determinant for viral replication and pathogenesis. We previously demonstrated that Nef, hijacking DC functional activity, subverts the DC arm of immune response to escape the adaptive immune attack. Here, we monitor the effect of Nef on the outcome of the innate immune response, focusing on the impact of Nef on DC/NK crosstalk. We demonstrate that Nef up-regulates the ability of DCs to stimulate the immunoregulatory NK cells (CD56(bright)) as assessed by the activated phenotype, up-regulation of their proliferative response and INF-gamma release. On the other hand, Nef-pulsed DCs inhibit cytotoxic NK cells (CD56(dim)), as assessed by the reduced HLA-DR surface expression, reduced proliferation and cytotoxic activity. Moreover, in the presence of Nef-pulsed DCs, we found a significant up-regulation of TNF-alpha secretion and a significant reduction of IL-10, GM-CSF, MIP-1alpha and RANTES secretion. Our findings suggest that the Nef-induced dysregulation in the DC/NK cell crosstalk may represent a potential mechanism through which HIV escapes innate immune surveillance.

Impaired NK-cell-mediated cytotoxic activity and cytokine production in patients with endometriosis: a possible role for PCBs and DDE.

Endometriosis is a gynaecological disorder characterized by the presence and growth of endometrial tissue in ectopic sites. In this study we examined the immunological functions of patients with endometriosis and serum level of PCBs and p,p'-DDE to verify the impact of these environmental contaminants on the dysregulation of immune functions. We found that proliferative responses and immunoglobulin production were not dysregulated in patients with endometriosis while NK cell activity was significantly down-regulated in these patients. Moreover, a significant down-regulation of IL-1beta and IL-12 production was found in patients with respect to controls. Serum levels of PCBs and p,p'-DDE were found to be significantly higher in women with endometriosis than in the control group, with respect to the sum of the congeners most prominent in human tissues. In particular, total PCBs concentration in patients with endometriosis and controls was respectively 330 and 160 ng/g fat with respect to the most abundant congeners, while p,p'-DDE concentration was of 770 and 310 ng/g fat. Moreover, we found that normal human PBMC pulsed with PCBs, p,p'-DDE and their combination showed a significant down-regulation of NK cell cytotoxic activity and IL-1beta and IL-12 production. These findings suggest that changes in specific immune parameters correlate with elevated serum PCBs and DDE levels and endometriosis.

Leptin promotes differentiation and survival of human dendritic cells and licenses them for Th1 priming.

Leptin is an adipocyte-derived hormone/cytokine that links nutrition, metabolism, and immune homeostasis. Leptin is capable of modulating several immune responses. However, the effect of leptin on dendritic cells (DCs) has not yet been recognized. Because DCs are instrumental in the development of immune responses, in this study, we evaluated the impact of leptin on DC activation. We demonstrated the presence of leptin receptor in human immature and mature DCs both at mRNA and protein level and its capacity to transduce leptin signaling leading to STAT-3 phosphorylation. We found no consistent modulation of DC surface molecules known to be critical for their APC function in response to leptin. In contrast, we found that leptin induces rearrangement of actin microfilaments, leading to uropod and ruffle formation. At a functional level, leptin up-regulates the IL-1beta, IL-6, IL-12, TNF-alpha, and MIP-1alpha production. Coincident with this, leptin-treated DCs stimulate stronger heterologous T cell responses. Furthermore, we found that leptin down-regulates IL-10 production by DCs and drives naive T cell polarization toward Th1 phenotype. Finally, we found that leptin partly protects DCs from spontaneous and UVB-induced apoptosis. Consistent with the antiapoptotic effect of leptin, we observed the activation of NF-kappaB and a parallel up-regulation of bcl-2 and bcl-x(L) gene expression. These results provide new insights on the immunoregulatory function of leptin demonstrating its ability to improve DC functions and to promote DC survival. This is of relevance considering a potential application of leptin in immunotherapeutic approaches and its possible use as adjuvant in vaccination protocols.

HIV-1 Nef equips dendritic cells to reduce survival and function of CD8+ T cells: a mechanism of immune evasion.

The accessory HIV-1 Nef protein is a crucial determinant for viral replication and pathogenesis. During HIV infection, loss of immune control in the setting of a strong and broad HIV-specific T-lymphocyte response, leads to a lethal outcome through AIDS. Moreover, dysfunction of dendritic cells (DCs) may contribute to the immune suppression associated with AIDS progression. We recently demonstrated that exogenous Nef selectively activates immature DCs manipulating their phenotypical, morphological, and functional developmental program. Here, we tracked whether Nef, targeting DCs, could be involved in the dysregulation of CD8+ T cell responses. We found that Nef inhibits the capacity of DCs to prime alloreactive CD8+ T cell responses down-regulating their proliferation and functional competence. This coincides with the induction of CD8+ T cell apoptosis. Nef oversees apoptotic killing of CD8+ T cells up-regulating TNF-alpha and FasL production by DCs and interfering with the death receptor pathway in CD8+ T cells and thus activating caspase 8. Our findings suggest that Nef may contribute to the immune evasion associated with HIV-1 infection, subverting DC biology. This may help explain the pleiotropic function that Nef plays during infection and makes this protein an attractive target for preventive and therapeutic intervention.

HIV-1 Nef triggers Vav-mediated signaling pathway leading to functional and morphological differentiation of dendritic cells.

The accessory HIV-1 Nef protein plays a key role in AIDS pathogenesis. We recently demonstrated that exogenous Nef triggers phenotypic and functional differentiation of immature dendritic cells (DCs). Here we investigated whether the Nef-induced DC differentiation occurs with morphological remodeling and have focused on the interference of Nef in the signaling pathways that regulates DC maturation. We found that exogenous Nef enters immature DCs, promoting their functional and morphological differentiation. Specifically, Nef promotes interleukin (IL) -12 release, which closely fits with nuclear factor (NF) -kappaB activation. Nef induces rearrangement of actin microfilaments, leading to uropod and ruffle formation. Moreover, Nef increases the capacity of DCs to form clusters with allogeneic CD4+ T cells, improving immunological synapse formation. Searching for molecules involved in Nef-triggered signaling pathways driving the DC maturation, we found that Nef targets Vav and promotes its tyrosine phosphorylation, associated with its nucleus-to-cytoplasm redistribution. This has a direct effect on Vav guanine nucleotide exchange factor activity for the small GTPase Rac1. We hypothesize that targeting Vav, Nef modulates both early signaling events (such as cytoskeletal rearrangement) and delayed responses (such as transcriptional regulation), promoting DC differentiation. Our results highlight how Nef may enhance T lymphocyte activation, thus fostering virus dissemination, manipulating the DC arm of the immune response.

Cytotoxic necrotizing factor 1 enhances reactive oxygen species-dependent transcription and secretion of proinflammatory cytokines in human uroepithelial cells.

Uropathogenic Escherichia coli strains frequently produce a Rho-activating protein toxin named cytotoxic necrotizing factor type 1 (CNF1). We herein report that CNF1 promotes transcription and release of tumor necrosis factor alpha, gamma interferon, interleukin-6 (IL-6), and IL-8 proinflammatory cytokines and increases the production of reactive oxygen species (ROS) in uroepithelial T24 cells. The antioxidant N-acetyl-L-cysteine counteracts these phenomena, a fact which suggests a role for ROS-mediated signaling in CNF1-induced proinflammatory cytokine production.