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Staphylococcus epidermidis is commonly involved in biomaterial-associated infections. Bacterial small colony variants (SCV) seem to be well adapted to persist intracellularly in professional phagocytes evading the host immune response. We studied the expression of PD-L1/L2 on macrophages infected with clinical isolates of S. epidermidis SCV and their parent wild type (WT) strains. The cytokine pattern which is triggered by the examined strains was also analysed. In the study, we infected macrophages with S. epidermidis WT and SCV strains. Persistence and release from macrophages were monitored via lysostaphin protection assays. Moreover, the effect of IFN-γ pre-treatment on bacterial internalisation was investigated. Expression of PD-L1/L2 molecules was analysed with the use of FACS. Inflammatory reaction was measured by IL-10, TNF-α ELISAs, and transcriptional induction of TNF-α. Our study revealed that clinical SCV isolates were able to persist and survive in macrophages for at least 3 days with a low cytotoxic effect and a reduced proinflammatory response as compared to WT strains. Bacteria upregulated PD-L1/L2 expression on macrophages as compared to non-stimulated cells. The results demonstrated that the ability of S. epidermidis SCVs to induce elevated levels of anti-inflammatory cytokine, IL-10, and reduced transcriptional induction of TNF-α, together with expression of PD-L1 on macrophages and the ability to persist intracellularly without damaging the host cell could be the key factor contributing to chronicity of SCV infections.

This study investigated the immunological factors, such as neutrophils number, the level of myeloperoxidase and IL-12, IL-10, TNF-alpha, IFN-gamma, that additionally might correlate with increased susceptibility to Candida infections in cancer patients. A total of 105 cancer patients were evaluated. Patients were examined twice for Candida colonization and presence of Candida antigen and DNA in bloodstream. Serum concentrations of MPO and selected cytokines were quantified by ELISA. The values for myeloperoxidase were decreased in Candida-colonized as well as deep-infected cancer patients groups, compared to healthy persons. In the group of patients suspected of deep candidiasis, we observed significantly elevated level of IFN-gamma compared to control. In the group of Candida-colonized patients, the concentrations of IL-12, TNF- alpha and IFN-gamma were significantly heightened when compared to control.MPO deficiency seems to be one of the important risk factor for deep candidiasis independently of the neutrophil count. The disturbances in cytokines levels in cancer patients group can be connected with underlying cancer disease, its treatment as well as Candida infection. The decreased level of TNF-alpha, in particular may be connected with Candida invasion.

Infection with Mycobacterium tuberculosis is accompanied by an intense inflammatory response. Recently, a new mediator of inflammation, HMGB1 protein has been identified that contributes to acute lung injury. However, its role in the systemic inflammatory response in tuberculosis has not been thoroughly investigated. We investigated the systemic levels of HMGB1 and TNF-α in patients with active and latent lung tuberculosis as a prognostic marker of disease activity. The study was performed to 70 patients with confirmed Mycobacterium tuberculosis infection and other than tuberculosis lung diseases and in 20 healthy persons. Serum HMGB1 and TNF-α concentrations were measured by ELISA. The highest concentration of HMGB1 was detected in the bloodstream of people with Mtb infection (latent and active). Its concentration increased significantly in sera of patients with active tuberculosis (47.5 ng/ml), compared to patients with other lung diseases (36.87 ng/ml). TNF-α had significantly higher concentration in a patients group compared to healthy controls, with the highest concentration in the LTBI group of patients (0.136 ng/ml). We observed a strong positive correlation between TNF-α and HMGB1 concentrations in patients with tuberculosis infections. We conclude that HMGB1 is secreted during active and latent tuberculosis in the highest amounts compared to other lung diseases.