Toll-like receptor 2-mediated induction of human beta-defensin 2 expression by Leptospira interrogans in human kidney cells.

BACKGROUND: Leptospirosis is a zoonotic disease caused by Leptospira interrogans. Severe leptospirosis is often accompanied by kidney dysfunction caused by chronic infection. The kidney pathology involves bacterial invasion and inflammation caused by pro-inflammatory cytokines. Human beta defensins (hBDs) are antimicrobial peptides induced by microbial infection and/or pro-inflammatory cytokines. One function of hBDs is the recruitment of immune cells that leads to inflammation. However, the expression of hBDs by kidney epithelium in response to pathogenic Leptospira has never been investigated. OBJECTIVE: To determine the expression of hBDs in human kidney epithelium responses to Leptospira. METHODS: Human kidney cells were infected with Leptospira interrogans serovar Autumnalis in the presence or absence of anti-TLR2 neutralizing antibody (Ab) for 6 hours. TLR2, hBDs and pro-inflammatory cytokines mRNA expressions were analyzed by quantitative polymerase chain reaction (qPCR). RESULTS: Pathogenic Leptospira upregulated the expressions of pro-inflammatory cytokines and hBD2, but not TLR2, hBD1 and hBD3 in kidney cells. The expressions of hBD2 and pro-inflammatory cytokines were inhibited in the presence of anti-hTLR2 neutralizing Ab. CONCLUSIONS: Our results provide the first evidence that pathogenic Leptospira induces hBD2 expression in kidney cells. The expressions of pro-inflammatory cytokines and hBD2 in the cells in response to pathogenic Leptospira are regulated by TLR2. Pro-inflammatory cytokines and hBD2 might be play role in recruitment of immune cells to the kidney and contribute to the development of inflammation-mediated tissue damage in the kidney. However, further study is needed to improve the understanding of the role of these molecules in immune response activation.

Toll-like receptor-mediated innate immune responses by recognition of the recombinant dormancy-associated Mycobacterium tuberculosis proteins Rv2659c and Rv1738.

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) poses a major threat to the global public health. Importantly, latent tuberculosis infection (LTBI) still impedes the elimination of TB incidence since it has a substantial risk to develop active disease. A multi-stage subunit vaccine comprising active and latency antigens of Mtb has been raised as the promising vaccine to trigger immune protection against all stages of TB. Therefore, the discovery of new antigens that could trigger broad immune response is essential. While current development of TB vaccine mainly focuses on protective immunity mediated by adaptive immune response, the knowledge on triggering the innate immune response by antigens is still limited. We showed that recombinant dormancy-associated Mtb proteins Rv2659c and Rv1738 were recognized by human innate immune recognition molecules, Toll-like receptors (TLRs) 2 and 4 by using HEK-Blue™ hTLR2/hTLR4 systems. We further demonstrated that these two proteins activated phosphorylated NF-κB p65 (Ser536) in the human CD14+ blood cells. We also investigated that these two proteins significantly induced level of pro- and anti-inflammatory cytokines (IL-1ß, IL-6, IL-8, IL-10 and TNF-α) which were mediated through TLR2 and TLR4 pathways in human peripheral blood mononuclear cells (hPBMCs). These findings suggest that proteins Rv2659c and Rv1738 stimulated innate immune response targeting TLR2 and TLR4 to produce inflammatory cytokines, and their benefits would be valuable for the development of an effective prophylactic tuberculosis vaccine.

Characterization of limbal explant sites: Optimization of stem cell outgrowth in in vitro culture.

Simple limbal epithelial transplantation (SLET) and cultivated limbal epithelial transplantation (CLET) are proven techniques for treating limbal stem cell deficiency (LSCD). However, the precise regions that are most suitable for preparing explants for transplantation have not been identified conclusively. Accordingly, this in vitro study aimed at determining ideal sites to be selected for tissue harvest for limbal stem cell culture and transplantation. We evaluated cell outgrowth potential and the expression of stem cell markers in cultures from 48 limbal explants from five cadaveric donors. The limbal explants were generated from the three specific sites: Lcor (located innermost and adjacent to the cornea), Lm (middle limbus), and Lconj (located outermost adjacent to the conjunctiva). We found that explants from the Lconj and Lm sites exhibited higher growth potential than those from the Lcor site. Transcript encoding the stem cell marker and p63 isoform, ΔNp63, was detected in cells from Lm and Lconj explants; expression levels were slightly, though significantly (p-value < 0.05), higher in Lm than in Lconj, although expression of ΔNp63α protein was similar in cells from all explants. Differential expression of ATP-Binding Cassette Subfamily G Member 2 (ABCG2) did not reach statistical significance. Immunohistochemistry by indirect immunofluorescence analysis of limbus tissue revealed that the basal layer in explant tissue from Lconj and Lm contained markedly more stem cells than found in Lcor explant tissue; these findings correlate with a higher capacity for growth. Collectively, our findings suggest that explants from the Lconj and Lm sites should be selected for limbal cell expansion for both CLET and SLET procedures. These new insights may guide surgeons toward specific limbal sites that are most suitable for stem cell culture and transplantation and may ultimately improve treatment outcomes in the patients with LSCD.

Involvement of Toll-like receptor 2 on human corneal epithelium during an infection of Pythium insidiosum.

BACKGROUND: Pythium insidiosum, a pathogenic oomycete, is a common causative organism of infectious corneal ulcer. Studying the innate immune response at the ocular surface is important for better understanding of the underlying pathogenesis and host defense against P. insidiosum infection. OBJECTIVE: The present study aims to investigate the role of Toll-like receptor (TLR)2 on human corneal epithelial cells (HCECs) in P. insidiosum infection. METHODS: Human embryonic kidney (HEK) cells were stimulated with either P. insidiosum zoospores or hyphae. NF-κB activation was determined by spectrophotometric measurement of secreted embryonic alkaline phosphatase (SEAP) levels. The role of TLR2 in P. insidiosum infection was studied in HCECs and monocyte derived macrophages (MDMs) using anti-TLR2 neutralizing antibody. The expression levels of pro-inflammatory cytokines were determined. RESULTS: Both P. insidiosum hypha and zoospore stimulated TLR2-dependent NF-κB activation in HEK-Blue™-hTLR2 cells in dose-dependent manner. IL-6 and IL-8, but not IL-1ß, were upregulated in HCECs after stimulation with P. insidiosum. Blockade of TLR2 on HCECs altered neither IL-6 nor IL-8 expressions. In contrast, the 3 cytokines were upregulated in the stimulated MDMs and the expression levels of IL-1ß and IL-8 but not IL-6 were attenuated in TLR2 blockade MDMs. CONCLUSIONS: P. insidiosum was recognized by human TLR2 on HEK cells. The mRNA expression levels of certain cytokines were dependent of TLR2 in P. insidiosum infected MDMs but not HCECs at early stage of infection.

Anti-Mycoplasma Activity of Daptomycin and Its Use for Mycoplasma Elimination in Cell Cultures of Rickettsiae.

Mycoplasma contamination detrimentally affects cellular functions and the growth of intracellular pathogens in cell cultures. Although several mycoplasmacidal agents are commercially available for sterile cell cultures, they are not applicable to rickettsia-infected cells. In our attempt to find an anti-mycoplasma drug for contaminated rickettsial cultures, we determined the susceptibilities of three common Mycoplasma species to daptomycin. Mycoplasma orale and M. arginini showed low-level resistance to daptomycin (minimum inhibitory concentration, MIC = 2 mg/L), whereas M. hyorhinis was high-level resistant (MIC = 32 mg/L). However, some Mycoplasma isolates developed higher resistance to daptomycin after failed treatments with inadequate doses or durations. An aminoglycoside (gentamicin) was still active against M. hyorhinis and could be used in Orientia cultures. For complete eradication of mycoplasmas in Rickettsia cultures, we recommend a 3-week treatment with daptomycin at 256 mg/L. In contaminated Orientia cultures, daptomycin at 32 mg/L was effective in eradicating M. orale, whereas either gentamicin or amikacin (100 mg/L) was effective in eradicating M. hyorhinis. Unlike each drug alone, the combinations of daptomycin plus clindamycin and/or quinupristin/dalfopristin proved effective in eradicating M. hyorhinis. In summary, our study demonstrated the in vitro anti-mycoplasma activity of daptomycin and its application as a new mycoplasma decontamination method for Rickettsia and Orientia cultures.

Epithelial analysis of simple limbal epithelial transplantation in limbal stem cell deficiency by in vivo confocal microscopy and impression cytology.

Simple limbal epithelial transplantation (SLET) is a relatively new treatment for severe limbal stem cell deficiency. Outcomes of treatment are typically determined based on clinical manifestations. In this prospective-multicenter study, we aimed to analyze the epithelial phenotypes of the corneas after SLET using IVCM and IC, and correlated them with clinical findings. Ten eyes of nine patients, who underwent SLET (five autologous SLET and five living-related SLET) were recruited. A set of examinations included slit-lamp biomicroscopy, corneal in vivo confocal microscopy (IVCM), and impression cytology (IC) was performed in all eyes at least twice (≥ 3-month interval) postoperatively. Then, a correlation between findings of the three examinations was analyzed. There were seven eyes with clinical success (no central neovascularization) showed pure corneal epithelial phenotype or mixed corneal-conjunctival phenotypes (mostly cornea) in either IVCM or IC. Three eyes with clinical failure, presented with peripheral and central neovascularization, showed total or predominant conjunctival phenotype in IVCM and sole conjunctival phenotype in IC. From a total of 22 sets of examinations, there was a high correlation between clinical manifestation vs. IC (κ = 0.844, observed agreement = 81.82%) and a substantial correlation between clinical manifestation vs. IVCM (κ = 0.727, observed agreement = 76.19%) and between IVCM versus IC (κ = 0.729, observed agreement = 76.19%). In conclusion, IVCM and IC facilitate determination of epithelial phenotype of the cornea after SLET. There was a substantial to high correlation between IVCM, IC and clinical presentations. Findings observed by IVCM and IC may allow early detection of epithelial alterations in eyes underwent SLET before clinical recognition.

Role of Toll-like receptor 2 in mediating the production of cytokines and human beta-defensins in oral mucosal epithelial cell response to Leptospiral infection.

BACKGROUND: Pathogenic Leptospira spp. is the causative agent of leptospirosis. Oral mucosal cavity is one of portal entry for this bacterium. Oral mucosal epithelium provides a physical barrier and secretes cytokines, chemokines and antimicrobial peptides (AMPs) in response to microbial infection. Human ß-defensins (hBDs); hBD1, hBD2, and hBD3 are predominantly AMPs expressed in the oral cavity. Toll-like receptors (TLRs) have been reported in hBD regulation. TLR2 recognizes leptospiral lipopolysaccharide, and plays a key role in the early control of leptospirosis. OBJECTIVE: The aim of this study is to investigate the role of TLR2 in mediating the production of cytokines and hBDs in oral mucosal epithelial cell response to leptospiral infection. METHODS: Cultivated oral mucosal epithelial cells were prepared, characterized, and compared with oral mucosal tissues. The TLR1-10 and hBD mRNA expressions were examined. Pro-inflammatory cytokine and hBD1-3 expressions in response to leptospires were determined by quantitative (q) RT-PCR. RESULTS: The cultivated oral epithelium expressed TLR2 and hBD1-3. The induction of IL-ßIL-8, TNF-α, and hBD2 were increased in response to Leptospira via TLR2 recognition. CONCLUSION: The characteristics of primary epithelial cells and tissue were similar in terms of TLR expression. All primary epithelial cells expressed TLR2 and hBD1-3. We used primary epithelial cells to study response to L. interrogans. Our results yielded the first evidence that human TLR2 regulates hBD2 expression in oral mucosa epithelial responded to L. interrogans. Expression of hBD2 may act to neutralize the virulence or prevent the invasion of L. interrogans at the portal of entry.