Exome sequencing identifies novel compound heterozygous IFNA4 and IFNA10 mutations as a cause of impaired function in Crohn's disease patients

The SERPINB4 gene mutation identified in twin patients with Crohn's disease impaires the intestinal epithelial cell functions

Crohn's disease (CD) is a chronic inflammatory autoimmune disease of unknown etiology. To identify new targets related to the initiation of CD, we screened a pair of twins with CD, which is a rare phenomenon in the Chinese population, for genetic susceptibility factors. Whole-exome sequencing (WES) of these patients revealed a mutation in their SERPINB4 gene. Therefore, we studied a wider clinical cohort of patients with CD or ulcerous colitis (UC), healthy individuals, and those with a family history of CD for this mutation by Sanger sequencing. The single-nucleotide difference in the SERPINB4 gene, which was unique to the twin patients with CD, led to the substitution of lysine by a glutamic acid residue. Functional analysis indicated that this mutation of SERPINB4 inhibited the proliferation, colony formation, wound healing, and migration of intestinal epithelial cells (IECs). Furthermore, mutation of SERPINB4 induced apoptosis and activated apoptosis-related proteins in IECs, and a caspase inhibitor significantly reduced these effects. Transcriptome sequencing revealed that the expression of genes encoding proinflammatory proteins (IL1B, IL6, IL17, IL24, CCL2, and CXCR2) and key proteins in the immune response (S100A9, MMP3, and MYC) was significantly upregulated during SERPINB4 mutant-induced apoptosis. Thus, the heterozygous SERPINB4 gene mutation causes the dysfunction of IECs, which would disrupt the intestinal epithelial barrier and contribute to the development of intestinal inflammation. The activation of SERPINB4 might represent a novel therapeutic target for inflammatory bowel disease.

Pilot Analyses of Interferon Subtype Expression Profiles in Patients with Herpes Zoster or Postherpetic Neuralgia

Postherpetic neuralgia (PHN) is a painful neuropathic complication resulting from herpes zoster (HZ). The pain manifests in peripheral nerves infected by herpesviruses, mostly from reactivation of latent varicella zoster virus. Mechanistic descriptions suggest that PHN develops because of disrupted immune system signaling and inflammation or peripheral nerve damage; however, the pathophysiology is not clear. It is difficult to predict/prevent PHN manifestations of HZ patients due to the lack of accurate diagnostics. In this study, sera from healthy controls, HZ patients, and PHN patients were subjected to an interferon (IFN) expression profile (IEP) study. The corresponding cDNAs were analyzed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) using primer pairs against a panel of 21 different IFN subtypes. The results showed that distinct IEPs were observed among HZ and PHN cohorts in comparison to the healthy controls. Together, this pilot study suggested that the IEP study may be used as a molecular tool for diagnosis of PHN and assist in designing new PHN therapeutic protocols.

Divalent metal-ion transporter 1 is decreased in intestinal epithelial cells and contributes to the anemia in inflammatory bowel disease

Divalent metal-ion transporter 1 (DMT1) has been found to play an important role in the iron metabolism and hemogenesis. However, little is known about the potential role of DMT1 in the pathogenesis of anemia from patients with inflammatory bowel disease (IBD). Herein, we investigated expression of DMT1 in the intestinal mucosa by quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry, and found that DMT1 was significantly decreased in the inflamed mucosa of active IBD patients compared with that in those patients at remission stage and healthy controls. To further study the mechanism, we cultured HCT 116 cell line in vitro. Expression of DMT1 in HCT116 was demonstrated to be markedly decreased under stimulation with TNF for 24 and 48 h, while JNK inhibitor (JNK-IN-7) could significantly reverse the decrease. Interestingly, anti-TNF therapy successfully improved anemia in clinical responsive Crohn’s disease patients, and DMT1 was found to be markedly up-regulated in intestinal mucosa. Taken together, our studies demonstrate that decreased expression of DMT1 in intestinal mucosa leads to compromised absorption and transportation of iron and that blockade of TNF could rescue anemia and promote DMT1 expression in gut mucosa. This work provides a therapeutic approach in the management of anemia in IBD.