Paneth cell α-defensin misfolding correlates with dysbiosis and ileitis in Crohn’s disease model mice

Abstract

Crohn’s disease (CD) is an intractable inflammatory bowel disease, and dysbiosis, disruption of the intestinal microbiota, is associated with CD pathophysiology. ER stress, disruption of ER homeostasis in Paneth cells of the small intestine, and α-defensin misfolding have been reported in CD patients. Because α-defensins regulate the composition of the intestinal microbiota, their misfolding may cause dysbiosis. However, whether ER stress, α-defensin misfolding, and dysbiosis contribute to the pathophysiology of CD remains unknown. Here, we show that abnormal Paneth cells with markers of ER stress appear in SAMP1/YitFc, a mouse model of CD, along with disease progression. Those mice secrete reduced-form α-defensins that lack disulfide bonds into the intestinal lumen, a condition not found in normal mice, and reduced-form α-defensins correlate with dysbiosis during disease progression. Moreover, administration of reduced-form α-defensins to wild-type mice induces the dysbiosis. These data provide novel insights into CD pathogenesis induced by dysbiosis resulting from Paneth cell α-defensin misfolding and they suggest further that Paneth cells may be potential therapeutic targets.

Expression and Localization of Paneth Cells and Their α-Defensins in the Small Intestine of Adult Mouse

“…In Crohn’s disease, an intractable inflammatory bowel disease, it is known that lesion formation is predominant in the terminal ileum. The amount and the quality of α-defensins in Crohn’s disease have been shedding important insights into the pathogenesis and pathophysiology of the disease ( 42 , 45 , 46 ). Bacterial overgrowth is known to occur not only in the colon but in affected lesions in the terminal ileum in patients with severe ulcerative colitis.…”

Decrease of α-defensin impairs intestinal metabolite homeostasis via dysbiosis in mouse chronic social defeat stress model

“…Final DNA concentrations were determined at 260 nm using a NanoDrop 2000 spectrometer (Thermo Fischer Scientific). 16S ribosomal RNA genes were amplified by PCR from each fecal DNA sample using universal primer set of Bakt 341F (5′-cctacgggnggcwgcag) and Bakt 805R (5′-gactachvgggtatctaatcc) which covers the V3-V4 variable region 16 , 52 , 53 . PCR amplification was performed in 25-μl-volume reaction mixtures containing 12.5 ng of template DNA, 200 nM of each primer, and 1 × KAPA HiFi Hot Start Ready Mix (Kapa Biosystems) under the following conditions: 95 °C for 3 min, 25 cycles of 95 °C for 30 s, 55 °C for 30 s, and 72 °C for 30 s, followed by 72 °C for 5 min.…”

“…It has been reported that the absence of active α-defensin alters the composition of small intestinal microbiota in mice 14 , and oral administration of α-defensin rescues severe dysbiosis of graft-versus-host disease (GVHD) model mice 15 , indicating that α-defensin plays an important role in maintaining homeostasis of the intestinal microbiota. In addition, it has been known that α-defensin abnormalities cause dysbiosis and disruption of the intestinal metabolism in Crohn’s disease model mice 16 , 17 . Dysbiosis caused by Paneth cell damage with decreased α-defensin has been shown to relate to various diseases 18 , 19 .…”

Lower human defensin 5 in elderly people compared to middle-aged is associated with differences in the intestinal microbiota composition: the DOSANCO Health Study

“…It has been also reported that the expression level of HD5 is decreased in patients with Crohn's disease and obesity which are known to relate to dysbiosis [74,75]. Furthermore, we have revealed that both quantitative and qualitative impairments of α-defensin secretion are associated with pathological progressions of graft versus host disease and Crohn's disease model mice via dysbiosis [40][41][42]. Taken together, it is suggested that deficiencies of α-defensin secretion relate to the increased risk of several diseases via inducing dysbiosis.…”

“…Paneth cells have intracellular secretory granules rich in antimicrobial peptide α-defensins termed cryptdins (Crps) in mice [29,30] and human defensin (HD) 5 and 6 in humans [31,32], and contribute to innate enteric immunity by secreting α-defensins into the intestinal lumen in response to bacterial stimuli [33,34], cholinergic agents [35], and certain food factors [36]. Furthermore, Paneth cell α-defensins have been known to contribute to the regulation of the intestinal microbiota in their quantity and quality-dependent manners [37][38][39][40][41][42]. It has also been reported that the supply of Wnt signals to the stem cells by Paneth cells is diminished by aging [43,44], suggesting that Paneth cell function declines with aging.…”