Autophagy induced by hypoxia in pulpitis is mediated by HIF-1α/BNIP3.

OBJECTIVE: Hypoxia-inducible factor-1α (HIF-1α) and its downstream factor, 19 kDa BCL-2 interacting protein 3 (BNIP3), promote cellular autophagy under hypoxic conditions. However, their roles in pulpitis are unclear. Therefore, the changes in inflammatory response and autophagy levels caused by hypoxia during pulpitis were evaluated. Additionally, the regulatory mechanism of HIF-1α/BNIP3 in cellular autophagy in pulpitis was explored. DESIGN: Pulp from dental pulp tissues of healthy individuals and patients with pulpitis (n = 10) were exposed and combined with a low oxygen simulation chamber to construct pulpitis (n = 6), hypoxia (n = 6), and hypoxia+pulpitis (n = 6) rat models. Hematoxylin and eosin and immunohistochemical staining were used to detect the localization and expression levels of HIF-1α, BNIP3, and autophagy marker protein, LC3B. Transmission electron microscopy was used to confirm autophagosome formation. An in vitro hypoxic model of human dental pulp cells was established, and HIF-1α chemical inhibitor 3-(5'-hydroxymethyl-2'-furyl)- 1-benzylindazole (YC-1) was administered. Immunofluorescence and western blotting were used to detect the localization and protein levels of HIF-1α, BNIP3, and LC3B. RESULTS: Autophagy is significantly increased and HIF-1α and BNIP3 are elevated in inflamed dental pulp tissue. Both pulp exposure and hypoxia intervention cause inflammatory reactions in rat dental pulp tissue, accompanied by the autophagy activation. Hypoxia significantly enhances HIF-1α/BNIP3 and autophagy activation. BNIP3 downregulates and autophagy reduces after treatment with YC-1. CONCLUSIONS: In pulpitis, activation of the HIF-1α/BNIP3 signaling pathway driven by hypoxia leads to increased autophagy. This provides a new molecular explanation for autophagy activation in apical periodontitis and new insights into the pathogenesis of the disease.

[The prevalence of Candida albicans and its relationship with early childhood caries among children of Uygur and Han nationalities in Kashi city].

OBJECTIVE: To explore the relationship between the prevalence of Candida albicans and early childhood caries(ECC) among 3-5 years old children of Uygur and Han nationalities in Kashi city, Xinjiang province. METHODS: Totally 397 generally healthy children(Uyghurs 256, Hans141) aged 3-5 years were recruited randomly in Kashi city using the stratified cluster random method. Dental plaque samples were collected from carious tooth tissues of children with ECC and from supragingival tooth sites of caries free(CF) children, respectively. Plaque samples were cultured and Candida albicans were isolated selectively by using CHROM agar candida medium. The isolates were further identified using methods of germ tubes test, Gram stain and PCR molecular biology. The data were analyzed using Pearson χ(2) test and Spearman analysis. RESULTS: The prevalenses of Candida albicans were 44.5% (114/256) in Han children and 31.2%(44/141) in Urgur children, respectively(P=0.009). Candida albicans could be isolated from 48.8% (124/254) of ECC children, while 23.8% (34/143) of CF ones(P=0.000). The frequencies of Candida albicans acquisition of boys and girls of Uygur children were 51.2%(66/129) and 37.8%(48/127), respectively (P=0.031). The frequencies of Candida albicans acquisition increased with the decayed missing filled tooth (dmft) scores. For both Uygur and Hanchildren, the detection rates of Candida albicans were correlated with dmft scores(Uygur r=0.350, P=0.001; Han r=0.276, P=0.000). CONCLUSIONS: The oral Candida albicans distributions were different in Uygur and Han ethnic groups. There were significant correlations between the presence of Candida albicans and ECC severityas well as score of dmft. There was a difference of the Candida albicans distributions between boys and girls among Uygur children. Candida albicans might be one of the important cariogenic microorganisms in ECC.

[Genetic diversity of ATP synthase cab subunits amplified from Streptococcus mutans clinical isolates from Uyghur children with different caries susceptibility].

OBJECTIVE: To investigate the aciduricity and genetic diversity of ATP synthase subunit gene uncEBF derived from Uyghur children Streptococcus mutans (Sm) clinical isolates and the relationship between the genetic diversity of ATP synthase and Sm aciduric ability and caries susceptibility. METHODS: Forty-one Sm strains derived from 24 caries-active individuals and 17 caries-free individuals, including 16 strains displaying high acid tolerance and 17 strains displaying low acid tolerance. Solutions of all isolated Sm with same density were made and cultured at pH 4.0 to 7.0 brain heart infusion (BHI) liquid. Terminal growth situation was compared. Gene uncEBF of these isolates were amplified with specific primers from Sm genomic DNA, and the polymerase chain reaction (PCR) products were analyzed by PCR-restriction fragment length polymorphism (RFLP) and sequenced. RESULTS: Aciduric ability of Sm isolated from the high caries-susceptible children were higher than that isolated from caries-free group (P = 0.023). Alu I digested fragments of uncEBF displayed two different patterns A and B. The distributions of A and B genotype strains with different acidurance were different (P = 0.039). A genotype included 7 strains displaying high acid tolerance and 2 strains displaying low acid tolerance;B genotype included 9 strains displaying high acid tolerance and 15 strains displaying low acid tolerance. The distributions of A and B genotype strains in different caries-sensitivity groups were different (P = 0.009). A genotype included 7 high caries-susceptible strains and 12 caries-free strains; B genotype included 17 high caries-susceptible strains and 5 caries-free strain. Some of these amplified uncEBF genes from different genotype were sequenced and testified that there existed variation of Alu I recognized sites. CONCLUSIONS: The high cariogenecity of Sm strains isolated from caries-active children shows a close relationship with the high aciduric ability of the isolated Sm strains. uncEBF gene of Sm F-ATPase obviously exhibits genetic diversity.