Regulation of the innate immune response and gut microbiome by p53.

p53 is a key tumor suppressor mutated in half of human cancers. In recent years, p53 was shown to regulate a wide variety of functions. From the transcriptome analysis of 24 tissues of irradiated mice, we identified 553 genes markedly induced by p53. Gene Ontology (GO) enrichment analysis found that the most associated biological process was innate immunity. 16S rRNA-seq analysis revealed that Akkermansia, which has anti-inflammatory properties and is involved in the regulation of intestinal barrier integrity, was decreased in p53-knockout (p53-/- ) mice after radiation. p53-/- mice were susceptible to radiation-induced GI toxicity and had a significantly shorter survival time than p53-wild-type (p53+/+ ) mice following radiation. However, administration of antibiotics resulted in a significant improvement in survival and protection against GI toxicity. Mbl2 and Lcn2, which have antimicrobial activity, were identified to be directly transactivated by p53 and secreted by liver into the circulatory system. We also found the expression of MBL2 and LCN2 was decreased in liver cancer tissues with p53 mutations compared with those without p53 mutations. These results indicate that p53 is involved in shaping the gut microbiome through its downstream targets related to the innate immune system, thus protecting the intestinal barrier.

HLA-A*31: 01 and HLA-B*15:02 association with Stevens-Johnson syndrome and toxic epidermal necrolysis to carbamazepine in a multiethnic Malaysian population.

The majority of the carbamazepine-induced Stevens-Johnson syndrome and toxic epidermal necrolysis CBZ-SJS/TEN are associated with HLA-B*15:02 in Asian populations where this allele is common. In contrast, the association with HLA-A*31:01 is only reported in Japanese and Europeans. This study aimed to further investigate the association with HLA-A*31:01 besides HLA-B*15:02 in a multiethnic Malaysian population. Twenty-eight CBZ-SJS/TEN cases and 227 CBZ-tolerant controls were recruited. Association was tested by comparing carrier frequencies of the alleles between cases and controls. Significant associations were detected between HLA-B*15:02 and CBZ-SJS/TEN in independent ethnic groups: Malays [P=2.00×10; odds ratio (OR): 49.0; 95% confidence interval (CI): 9.36-256.81], Chinese (P=0.0047; OR: 14.3; 95% CI: 2.38-86.03) and Indians (P=0.04; OR: 13.8; 95% CI: 1.51-124.99). Combined analysis of all ethnic groups showed a significant association with OR Cochran-Mantel-Haenszel (ORCMH) of 26.6 (95% CI: 12.80-55.25; PCMH=2.31×10). In Indians, HLA-A*31:01 was found to be associated significantly with CBZ-SJS/TEN (P=0.023; OR: 10.4; 95% CI: 1.64-65.79) and combined analyses of both variants, HLA-A*31:01 and HLA-B*15:02, increased the strength of the association (P=0.0068; OR: 14.3; 95% CI: 2.20-92.9). Besides HLA-B*15:02, our study found a new association between HLA-A*31:01 and CBZ-SJS/TEN in Indians.

HLA-B*15:02 association with carbamazepine-induced Stevens-Johnson syndrome and toxic epidermal necrolysis in an Indian population: a pooled-data analysis and meta-analysis.

This study aimed to investigate the prevalence and association of HLA-B*15:02 with carbamazepine-induced Stevens-Johnson syndrome and toxic epidermal necrolysis (CBZ-SJS/TEN) in the Indian population in Malaysia, which mostly originated from Southern India. HLA-B alleles in five Indian case patients with CBZ-SJS/TEN and 52 CBZ-tolerant controls, and followed by a pooled sample of seven cases from two centers in Malaysia were analyzed. Positive association for HLA-B*15:02 with CBZ-SJS/TEN was detected in Indians (40% [2/5] vs. 3.8% [2/52], odds ratio [OR] 16.7, p = 0.0349), of which 80% (4/5) of the Indian patients originated from Southern India. A pooled sample of seven cases showed stronger association between HLA-B*15:02 and CBZ-SJS/TEN (57.1% [4/7] vs. 3.8% [2/52], OR 33.3, 95% confidence interval [CI] 4.25-162.21, p = 1.05 × 10(-3)). Subsequent meta-analysis on Indians from Malaysia and India further demonstrated a significant and strong association between HLA-B*15:02 and CBZ-SJS/TEN (OR 38.54; 95% CI 6.83-217.34, p < 1.0 × 10(-4)). Our study is the first on Indians predominantly from Southern India that demonstrated HLA-B*15:02 as a strong risk factor for CBZ-SJS/TEN despite a low population allele frequency. This stressed the importance of testing for HLA-B*15:02, irrespective of the ancestral background, including populations with low allele frequency.