Hepatitis B virus (HBV) infection is one of the most dangerous viral diseases, with innate immunity representing the first line of defense against the virus. In this branch of the immune system, neutrophils are considered key cellular mediators. To better understand the implication of neutrophils in the distinct stages of the disease, HBV-infected patients were enrolled in this study and categorized into three groups: patients with acute infection, chronic infection under treatment, and at early cirrhotic stage. To elucidate the role of inflammatory mediators and cellular mechanisms of neutrophilic origin in the course of the infection, both ex vivo and in vitro studies were performed. Increased levels of C-C motif chemokine ligand 2 (CCL2), interleukin (IL)-18, IL-33, and citrullinated histone H3 (CitH3)—an accurate marker of neutrophil extracellular traps (NETs)—were detected in the circulation of patients with acute infection or early cirrhosis. In parallel, sera from the aforementioned patient groups induced the formation of IL-1b-bearing NETs in neutrophils from healthy individuals. These inflammatory NETs affected primary fibroblasts towards acquiring a pro-fibrotic phenotype. These results suggest that NETs could be regarded as mediators in hepatitis B manifestations, while their therapeutic targeting could enhance the management of early-stage cirrhotic patients.

Hepatitis E virus (HEV), a common cause of viral hepatitis in developing countries, is mainly transmitted via the fecal–oral route, but also may be a prevalent hospital-transmitted agent among patients on regular hemodialysis due to parenteral transmission. Previous epidemiological studies among hemodialysis patients in Greece, using different diagnostic techniques, gave conflicting results. Τhe present study aimed to measure the exposure rate of hemodialysis patients of north-eastern Greece to HEV by estimating the overall seroprevalence, and to identify potential risk factors. Serum samples from all patients attending the hemodialysis centers of north-eastern Greece (n = 6) were tested for the presence of anti-HEV IgG antibodies using a modern and sensitive ELISA (Enzyme-linked Immunosorbent Assay) technique (Wantai). In total, 42 out of 405 hemodialysis patients were positive for anti-HEV IgG (10.4%), while all samples were negative for HEV RNA when tested using nested RT-PCR. HEV seropositivity among hemodialysis patients was significantly associated with area of residence and contact with specific animals (pork, deer). No association was found with religion, gender distribution and hemodialysis duration. This study showed an increased seroprevalence of HEV among hemodialysis patients in Greece. Agricultural or livestock occupation and place of residence seem to be independent factors that increase the risk of HEV infection. In conclusion, HEV infection calls for the regular screening of hemodialysis patients regardless of the hemodialysis duration or clinical symptoms.

Aim: In this cohort, we aimed to study the evolution of pregenomic RNA (pgRNA) during treatment and compare it with other disease scores such as FIB-4 and PAGE-B. Methods: Eighty-eight HBeAg negative CHB who received long-term treatment with NAs were included. A quantitative HBV S antigen (HBsAg) assay was performed, and viral HBV DNA was quantified by Polymerase Chain Reaction (PCR). Finally, viral RNA levels (pre-core RNA (preC RNA) and pgRNA) were analyzed using the RTPCR protocol. The FIB-4 score was calculated for all patients, depicting the cirrhosis course, while the platelet-related PAGE-B score contributed to the 5-year cumulative prognosis of hepatocellular carcinoma (HCC). Statistical multivariate analysis was performed using the R studio and CATREG SPSS optimal scaling algorithm of SPSS 26.0.0.0. Results: A total of 18.1% of our sample was positive for HBV pgRNA, delineating a positive correlation with cirrhosis and an apparently negative correlation with therapy duration. HBV pgRNA was not independently correlated with FIB-4 ( p = 0.137) after adjustment for aminotransferase/alanine transaminase (AST/ALT) ^1/2 , (AST) ^1/2 , 1/platelets (PLT), age, sex, HBsAg, HBV viral load, regimen administered, and therapy duration (ordinal regression ANOVA p < 10 ⁻¹² ; R reg 2 : 0.794). Moreover, HBV pgRNA was not independently correlated with PAGE-B ( p = 0.459) after adjustment for age, sex, AST, 1/PLT, duration of therapy, HBsAg, HBV viral load, regimen administered, and the presence of cirrhosis (ordinal regression ANOVA p < 10 ⁻¹² ; R reg 2 : 0.800). Conclusions: Based on our results, further longitudinal studies are needed to assess the potential usefulness of HBV pgRNA as prognosticator of liver fibrosis and susceptibility to HCC.

LL-37 has attracted significant research attention as a multifunctional antimicrobial peptide which is implicated in a broad spectrum of activities. It is the only human cathelicidin and represents a key molecule in host defense. Hence, it is described as possessing antimicrobial activity against a wide range of pathogens, including Gram-negative and Gram-positive bacteria, numerous viral species, and various fungi. Though it is widely recognized for its direct antimicrobial activity, it is a multifaceted immunomodulatory and tissue-protective molecule. Beyond host defense, LL-37 actively regulates inflammatory signaling, cellular interactions within the immune system, and mechanisms of tissue repair. Its ability to fine-tune immune responses and simultaneous regeneration highlights its dual role in inflammation control and wound healing. These pleiotropic functions place LL-37 in the spotlight between innate immunity and tissue homeostasis. This review aims to compile LL-37’s antimicrobial and immunomodulatory activities and highlight its wide range of potential clinical applications.

Legionella pneumophila (L. pneumophila) infection is characterized by a wide spectrum of manifestations, from influenza-like illness to life-threatening atypical pneumonia with multiorgan failure. The aim of our study was the assessment of in vitro and ex vivo neutrophil activation in L. pneumophila infections, as well as the role of neutrophils’ peptides such as LL-37 in infection. The ability of neutrophils to form ex vivo extracellular traps (NETs) in response to bacterial infection was examined by immunofluorescence. In parallel, patients’ sera, as well as opsonized standard L. pneumophila strains, were used for in vitro activation of neutrophils from healthy individuals. The serum levels of interleukins were assessed using the LEGENDplexTM Multi-Analyte Flow Assay Kit. Furthermore, citrullinated cf-DNA as a marker of neutrophil extracellular traps (NETs) was detected in the serum of patients with acute infection. It was demonstrated that neutrophils released NETs in vitro and ex vivo upon L. pneumophila (interaction in an autophagy-independent manner. Notably, IL-1b was detected on NETs, but an antimicrobial peptide LL-37 was absent. The lack of antimicrobial activity failed to inhibit bacterial proliferation. In addition, in vitro and ex vivo NETs formation was observed during the Clarithromycin treatment. Those NETs were decorated with bioactive antimicrobial peptide LL-37, which inhibits bacterial proliferation. The findings provide evidence that neutrophils release NETs in vitro and ex vivo by expressing the IL1β protein in them. The lack of expression of the antimicrobial peptide LL-37 on the NETs demonstrates the inability of the cells to inhibit proliferation, and consequently the elimination of L. pneumophila. Clarithromycin plays a dual role in the elimination.

Introduction: Chronic hepatitis B (CHB) is a widespread form of hepatitis B infection with advanced complications if unsupervised and untreated. It was previously reported that pregenomic RNA (pgRNA) can be detected in blood circulation as an indirect marker of HBV transcriptional activity. The aim of this study was to investigate the transcriptomic profile of pgRNA-positive patients with CHB in comparison to pgRNA-negative patients and to evaluate its role in innate immunity. Materials and methods: A total of 88 patients with CHB who were receiving nucleoside analogs (NAs) were enrolled in this study. The viral load and genotype, HBV pgRNA, and biochemical and virological markers were determined. Samples from eight CHB HBeAg-negative patients were sequenced. Four of them were positive for HBV pgRNA, while the rest were negative. These data were processed via bioinformatic tools. Bioinformatic analyses revealed common pathways such as platelet activation and neutrophil degranulation, for which experimental setups were organized. Platelet activation, as well as platelet–neutrophil interactions, was examined. Furthermore, the synthesis and expression of interleukins IL-1β, IL-17A, and LL-37 were studied. Results: The percentage of patients positive for HBV pgRNA in the study population was 18.1%. With respect to the transcriptomic analysis, which was performed via two distinct analyses, we identified common differentially expressed (DE) genes involved in platelet activation and neutrophil degranulation pathways. Afterwards, the induction of autophagy in platelets and the de novo synthesis of the peptide LL-37 were observed in platelets stimulated with HBV pgRNA-positive serum. Furthermore, a combined study of platelet–neutrophil interactions revealed the development of a proinflammatory phenotype characterized by high levels of IL-1β in neutrophils, accompanied by minimal NET formation. In conclusion, those findings were intended to demonstrate the overexpression of IL-1β and LL-37 in the liver tissue of patients with CHB. Conclusions: This study demonstrated that HBV pgRNA activates platelets in an autophagy-dependent manner. Moreover, the platelet–neutrophil axis is responsible for a proinflammatory phenotype in which IL-1β is overexpressed.