Temporal induction of secretory leukocyte protease inhibitor (SLPI) in odontoblasts by lipopolysaccharide and wound infection

Recombinant human secretory leukocyte protease inhibitor (rhSLPI) coated titanium enhanced human osteoblast adhesion and differentiation

Osseointegration is vital to success in orthopedic and dental reconstructions with implanted materials. The bone matrix or cells-particularly osteoblasts-are required to achieve functional contact on the implant surface. Osteoblast induction is therefore essential for osteogenesis to occur. Enhancement of osteoblast adhesion, proliferation, and differentiation, particularly by implant surface modifications, have been found challenging to develop. Secretory Leukocyte Protease Inhibitor (SLPI), a cation ionic protein with anti-inflammatory and anti-bacterial activities, showed activation in osteoblast proliferation and differentiation. However, the effects of coating recombinant human (rh) SLPI on a titanium alloy surface on human osteoblast adhesion, proliferation, and differentiation has never been investigated. In this study, titanium alloys (Ti-6Al-4V) were coated with rhSLPI, while human osteoblast adhesion, proliferation, differentiation, actin cytoskeletal organization, and gene expressions involved in cell adhesion and differentiation were investigated. The results indicate that coating titanium with 10-100 µg/ml rhSLPI enhanced the physical properties of the Ti surface and enhanced human osteoblast (hFOB 1.19) cell adhesion, activated actin dynamic, enhanced adhesive forces, upregulated integrins α1, α2, and α5, enhanced cell proliferation, mineralization, alkaline phosphatase activity, and upregulated ALP, OCN, and Runx2. This is the first study to demonstrate that coating SLPI on titanium surfaces enhances osseointegration and could be a candidate molecule for surface modification in medical implants.

The Role of Recombinant Secretory Leukocyte Protease Inhibitor to CD163, FGF-2, IL-1 and IL-6 Expression in Skin Wound Healing

Background

The wound healing process can be optimized through the addition of a biomaterial such as recombinant secretory leukocyte protease inhibitor (rSLPI). The SLPI is a non-glycosylated proteomic material that inhibits protease enzymes and has anti-inflammatory properties, thus accelerating wound healing. This study analyzed the administration of rSLPI doses 0.04 cc and 0.06 cc in skin wound healing on the CD163 expression of macrophages and cytokines such as interleukin 1 (IL-1), interleukin 6 (IL-6) and fibroblast growth factor 2 (FGF-2).

Materials and Methods

rSLPI produced from Escherichia coli TOP10 as the cloning host, BL21 (DE3) strains as the expression host and pET30a plasmids were used for the expression system construction. The wound was created on Wistar rat dorsal skin, then rSLPI 0.04 cc and 0.06 cc was administered. In the next four days, the back skin was biopsied and stained by immunohistochemistry to analyze the CD163, FGF-2, IL-1 and IL-6 expression.

Results

The administration of rSLPI increased CD163 and FGF-2 expression dependent on dose (p<0.05). On the other hand, administration of rSLPI decreased IL-1 and IL-6 expression depending on dose (p <0.05).

Conclusion

The administration of rSLPI is able to accelerate the wound healing process by increasing the CD163 and FGF-2 expression. The cytokines such as IL-1 and IL-6 decreased depending on rSLPI doses.

Role of Lipopolysaccharide, Derived from Various Bacterial Species, in Pulpitis—A Systematic Review

Lipopolysaccharide (LPS) is widely used for induction of inflammation in various human tissues, including dental pulp. The purpose of this study was to summarize current medical literature focusing on (1) cell types used by researchers to simulate dental pulp inflammation, (2) LPS variants utilized in experimental settings and how these choices affect the findings. Our study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We searched for studies reporting outcomes of lipopolysaccharide application on dental pulp cells in vitro using electronic databases: MEDLINE, Web of Science and Scopus. Having gathered data from 115 papers, we aimed to present all known effects LPS has on different cell types present in dental pulp. We focused on specific receptors and particles that are involved in molecular pathways. Our review provides an essential foundation for further research using in vitro models of pulpitis.

Effects of sclerostin on lipopolysaccharide-induced inflammatory phenotype in human odontoblasts and dental pulp cells

Previously we have demonstrated that sclerostin inhibits stress-induced odontogenic differentiation of odontoblasts and accelerates senescence of dental pulp cells (DPCs) Odontoblasts and DPCs are main functioning cells for inflammation resistance and tissue regeneration in dentine-pulp complex. Sclerostin is relevant for systemic inflammation and chronic periodontitis processes, but its effects on dental pulp inflammation remains unclear. In this study, we found that sclerostin expression of odontoblasts was elevated in lipopolysaccharide-induced inflammatory environment, and exogenous sclerostin increased the production of pro-inflammatory cytokines in inflamed odontoblasts. Furthermore, sclerostin activated the NF-κB signaling pathway in inflamed odontoblasts and the NF-κB inhibitor reversed the exaggerative effects of sclerostin on the pro-inflammatory cytokines production. Additionally, sclerostin promoted adhesion and migration of inflamed DPCs, while inhibiting odontoblastic differentiation of inflamed DPCs. Sclerostin also might enhance pulpal angiogenesis. Taken together, it can therefore be inferred that sclerostin is upregulated in inflamed odontoblasts under pulpal inflammatory condition to enhance inflammatory responses in dentine-pulp complex and impair reparative dentinogenesis. This indicates that sclerostin inhibition might be a therapeutic target for anti-inflammation and pro-regeneration during dental pulp inflammation.

Reactionary Versus Reparative Dentine in Deep Caries

The dentine-pulp complex response in deep caries is histological characterized by tertiary formation and mild chronic pulp inflammation. The quiescent primary odontoblasts are reactivated, laying down reactionary tertiary dentine. In more severe carious damage the primary odontoblasts die and reparative tertiary dentine is secreted by odontoblast-like cells, which are differentiated in adult teeth mainly from dental pulp stem cells DPSC. Though associated with reversible pulpitis DPSC still preserve in deep caries the capability of migration, proliferation and differentiation. Some common mechanisms of molecular signals involved in tertiary dentine formation might also explain the balance between inflammation and regeneration of dentine-pulp complex.

Cervical Local Immune Response for High-Risk Human Papillomavirus Infection: Involvement With Cervical Mucus SLPI Proteins

Purpose:

To evaluate cervical mucus secretory leukocyte protease inhibitor (SLPI) concentrations in patients with high-risk human papillomavirus (hrHPV) 16 or 18 positive and low-grade squamous intraepithelial lesions (LGSIL) or high-grade squamous intraepithelial lesions (HGSIL).

Method:

Patients with HPV 16 or 18 positive from 30 to 45 years of age whose cervical cancer screening results reported cytologically LGSIL or HGSIL were included in the study. In the control group, we included participants in the same age with cytology negative and HPV-negative healthy women. All cytological LGSIL or HGSIL results were histopathologically confirmed with colposcopic biopsy specimens. Finally, the study consisted of a total of 3 groups each containing 25 participants as follows: (1) Pap smear and HPV-negative control group, (2) HPV 16 or HPV 18 and LGSIL-positive participants, and (3) HPV 16 or 18 and HGSIL-positive participants. Cervical mucus SLPI levels were analyzed using the enzyme-linked immunosorbent assay method.

Results:

The mean cervical mucus SLPI levels were 32.94 ng/mL (range: 23-41.29 ng/mL) in the hrHPV + LGSIL group, 29.40 ng/mL (range: 21.03-38.95 ng/mL) in the hrHPV + HGSIL, and 18.75 ng/mL (range: 13.58-29.24 ng/mL) in the healthy control group. Cervical mucus SLPI levels were found to be significantly higher in the hrHPV + LGSIL and hrHPV + HGSIL groups compared to the control group (P < .001).

Conclusions:

The data from the present study indicate that SLPI seems to be one of the important immunomodulatory proteins that provide local immune response in cervical mucosa.

Secretory leukocyte protease inhibitor promotes differentiation and mineralization of MC3T3-E1 preosteoblasts on a titanium surface

Mineralized bone matrix constituted with collagenous and non-collagenous proteins was synthesized by osteoblasts differentiated from mesenchymal stem cells. Secretory leukocyte protease inhibitor (SLPI), a serine protease inhibitor, promotes cell migration and proliferation, and suppresses the inflammatory response. Recent studies reported that SLPI regulates the formation of dentin and mineralization by odontoblasts and increases the adhesion and viability of preosteoblasts on a titanium (Ti) surface. Ti and its alloys are widely used implant materials in artificial joints and dental implants owing to their biocompatibility with bone. Therefore, this study aimed to examine whether SLPI can be an effective molecule in promoting differentiation and mineralization of osteoblasts on a Ti surface. In order to investigate the effects of SLPI on osteoblasts, an MTT assay, PCR, western blotting and Alizarin Red S staining were performed. The results demonstrated that SLPI increased the viability of osteoblasts during differentiation on Ti discs compared with that of the control. The expression levels of SLPI mRNA and protein were higher than that of the control after treatment of osteoblasts with SLPI on Ti discs during differentiation. SLPI increased the formation of mineralized nodules and mRNA expression of alkaline phosphatase, dentin sialophosphoprotein, dentin matrix protein 1, bone sialoprotein, and collagen I in osteoblasts on Ti discs compared with that of the control. In conclusion, SLPI increases the viability and promotes the differentiation and mineralization of osteoblasts on Ti surfaces, suggesting that SLPI is an effective molecule for achieving successful osseointegration between osteoblasts and a Ti surface.

Epigenetic regulation in dental pulp inflammation

Dental caries, trauma, and other possible factors could lead to injury of the dental pulp. Dental infection could result in immune and inflammatory responses mediated by molecular and cellular events and tissue breakdown. The inflammatory response of dental pulp could be regulated by genetic and epigenetic events. Epigenetic modifications play a fundamental role in gene expression. The epigenetic events might play critical roles in the inflammatory process of dental pulp injury. Major epigenetic events include methylation and acetylation of histones and regulatory factors, DNA methylation, and small non-coding RNAs. Infections and other environmental factors have profound effects on epigenetic modifications and trigger diseases. Despite growing evidences of literatures addressing the role of epigenetics in the field of medicine and biology, very little is known about the epigenetic pathways involved in dental pulp inflammation. This review summarized the current knowledge about epigenetic mechanisms during dental pulp inflammation. Progress in studies of epigenetic alterations during inflammatory response would provide opportunities for the development of efficient medications of epigenetic therapy for pulpitis.

An Overview of Pathogen Recognition Receptors for Innate Immunity in Dental Pulp

Pathogen recognition receptors (PRRs) are a class of germ line-encoded receptors that recognize pathogen-associated molecular patterns (PAMPs). The activation of PRRs is crucial for the initiation of innate immunity, which plays a key role in first-line defense until more specific adaptive immunity is developed. PRRs differ in the signaling cascades and host responses activated by their engagement and in their tissue distribution. Currently identified PRR families are the Toll-like receptors (TLRs), the C-type lectin receptors (CLRs), the nucleotide-binding oligomerization domain-like receptors (NLRs), the retinoic acid-inducible gene-I-like receptors (RLRs), and the AIM2-like receptor (ALR). The environment of the dental pulp is substantially different from that of other tissues of the body. Dental pulp resides in a low compliance root canal system that limits the expansion of pulpal tissues during inflammatory processes. An understanding of the PRRs in dental pulp is important for immunomodulation and hence for developing therapeutic targets in the field of endodontics. Here we comprehensively review recent finding on the PRRs and the mechanisms by which innate immunity is activated. We focus on the PRRs expressed on dental pulp and periapical tissues and their role in dental pulp inflammation.

SLPI knockdown induced pancreatic ductal adenocarcinoma cells proliferation and invasion

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease and still continues to have the worst prognosis of all gastrointestinal malignancies. Reports have demonstrated that secretory leukocyte protease inhibitor (SLPI) is overexpressed in various cancers and may be a potential therapeutic strategy for the treatment of different cancers. However, the possible role of SLPI in PDAC is still unknown. In the present study, we investigate the effects of SLPI gene knockdown on the biological behavior of human pancreatic cancer cells. The expressions of SLPI were detected, by qRT-PCR and Western blot, in human PDAC tissues as well as AsPC-1, BxPC-3 and PANC-1 cells. After transfection with siRNA targeting to SLPI, SLPI expression was detected by qRT-PCR and Western blot in cells. Cell proliferation and apoptosis were also evaluated by MTT assay and flow cytometry (FCM). The trans-well assays were also employed to explore the effects of SLPI knockdown on the migration and invasion of PDAC cells in vitro.

RESULTS

The expressions of SLPI derived from human PDAC and PDAC cell lines were significant higher than those of control groups, respectively (P < 0.05). Regression analysis showed elevated SLPI level was positive correlated with development of PDAC. The siRNA target to SLPI significantly decreased the expressions of SLPI in these PDAC cell lines. Following SLPI-siRNA transduction, the proliferative capacity of the AsPC-1, BxPC-3 and PANC-1 cells was significantly inhibitions, compared to the blank (PDAC-wild type cells) and negative (non-targeting scrambled siRNA transduced PDAC cells) control ones, respectively (P < 0.05). Moreover, SLPI knockdown significantly increased the apoptosis fractions and reduced the migration and invasion of PDAC cells in vitro (P < 0.05).

CONCLUSIONS

The present study demonstrated that: i) SLPI played an important role in PDAC progression; ii) SLPI might be an important characteristic of malignant PDAC associated with migration and invasion in vitro; and iii) siRNA targeting to SLPI might be a potential therapeutic strategy for the treatment of PCC.

Induction of secretory leukocyte protease inhibitor (SLPI) in estradiol valerate (EV) induced polycystic ovary

The excessive administration of estradiol valerate induces polycystic ovary syndrome by formation of follicular cysts. Secretory leukocyte protease inhibitor (SLPI) promotes wound healing by decreasing the excessive inflammatory response, stimulating keratinocyte proliferation and increasing collagen deposition through the inhibition of protease activity. In this study, SLPI expression was high in the ovarian stroma, corpus luteum, unilaminar primary follicle, multilaminar primary follicle and granulose layer of the antral follicle in polycystic ovary (PCO) compared to the normal ovary. SLPI was expressed strongly in the theca around the cyst in PCO compared to the mature follicle in the normal ovary. The levels of SLPI mRNA and protein expression were higher in PCO than in the normal ovary, and the level of MMP-2 expression was lower in PCO. These results showed that the formation of a cyst was initiated from a multilaminar primary follicle and SLPI expression was increased depending on the morphological changes in the follicle and ovarian stroma. Therefore, an increase in SLPI may be related to the suppression of tissue disruption, and act as a protease inhibitor in PCO, suggesting that SLPI increases independently of the estrogen concentration in pathological tissues.