Unraveling the role of natural killer cells in leishmaniasis.

NK cells are known as frontline responders that are efficient in combating several maladies as well as leishmaniasis caused by Leishmania spp. As such they are being investigated to be used for adoptive transfer therapy and vaccine. In spite of the lack of antigen-specific receptors at their surface, NK cells can selectively recognize pathogens, accomplished by the activation of the receptors on the NK cell surface and also as the result of their effector functions. Activation of NK cells can occur through interaction between TLR-2 expressed on NK cells and. LPG of Leishmania parasites. In addition, NK cell activation can occur by cytokines (e.g., IFN-γ and IL-12) that also lead to producing cytokines and chemokines and lysis of target cells. This review summarizes several evidences that support NK cells activation for controlling leishmaniasis and the potentially lucrative roles of NK cells during leishmaniasis. Furthermore, we discuss strategies of Leishmania parasites in inhibiting NK cell functions. Leishmania LPG can utilizes TLR2 to evade host-immune responses. Also, Leishmania GP63 can directly binds to NK cells and modulates NK cell phenotype. Finally, this review analyzes the potentialities to harness NK cells effectiveness in therapy regimens and vaccinations.

Molecular characterization of carbapenem-resistant Pseudomonas aeruginosa isolated from four medical centres in Iran.

BACKGROUND: Understanding the mechanisms of antibiotic resistance is important for designing new therapeutic options and controlling resistant strains. The goal of this study was to look at the molecular epidemiology and mechanisms of resistance in carbapenem-resistant Pseudomonas aeruginosa (CRPA) isolates from Tabriz, Iran. METHODS: One hundred and forty P. aeruginosa were isolated and antibiotic susceptibility patterns were determined. Overproduction of AmpC and efflux pumps were discovered using phenotypic techniques. Polymerase chain reaction (PCR) was used to determine the presence of carbapenemase-encoding genes. In addition, the expressions of OprD and efflux pumps were evaluated by the Real-Time PCR. Random amplified polymorphic DNA typing (RAPD) was performed for genotyping. RESULTS: Among 140 P. aeruginosa isolates, 74 (52.8%) were screened as CRPA. Overexpression of efflux systems was observed in 81% of isolates, followed by decreased expression of OprD (62.2%), presence of carbapenemase genes (14.8%), and overproduction of AmpC (13.5%). In most isolates, carbapenem resistance was multifactorial (60.8%). According to our results, the prevalence of CRPA is at alarming levels. Overexpression of efflux systems was the most common mechanism of carbapenem resistance. CONCLUSION: Most isolates may originate in patients themselves, but cross-infection is possible. Therefore, we suggest a pattern shift in the strategy of CRPA in our setting.

Risk factors for mortality in hospitalized patients infected with carbapenem-resistant Pseudomonas aeruginosa in Iran.

Introduction: Mortality due to carbapenem-resistant Pseudomonas aeruginosa (CRPA) infection has increased worldwide in recent years. The risk factors associated with hospital settings in Iran and the role of strain resistance mechanisms in many studies are unclear. Methods: A retrospective study was conducted on consecutive non-repetitive patients with CRPA infections isolated from seven major hospitals from northwest of Iran. We evaluated different risk factors and characteristics of bacteria for the death or survival of patients. Results: In this study, 116 CRPA isolates were obtained from patients admitted to seven hospitals. Forty-one (35.3%) patients were enrolled in the study of mortality risk factors. Significant risk factors associated with mortality included the site of infection, hospitalization in different wards, the use of invasive devices, and the type of carbapenem resistance mechanisms. Conclusions: ICU admission, the use of mechanical ventilation and chest tube and infection with pandrug-resistant strains were the most important factors in increasing mortality due to CRPA infection. These results suggested that the clinicians should emphasize the proper use of antibiotic and invasive procedures.