Lactobacillus acidophilus L-92 Cells Activate Expression of Immunomodulatory Genes in THP-1 Cells

Xiong Fu Powder Regulates the Intestinal Microenvironment to Protect Bones Against Destruction in Collagen-Induced Arthritis Rat Models

Background

Changes in the intestinal microenvironment affected bone destruction in rheumatoid arthritis (RA), and spleen deficiency (SD) was closely related to the intestinal microenvironment. In this study, we aimed to explore the aggravation of SD on collagen-induced arthritis (CIA) and the bone protection of compound Xiong Fu powder (XFP) on CIA with SD (SD-CIA) based on the intestinal microenvironment.

Method

An SD-CIA rat model was established using Rheum officinale Baill. decoction combined with CIA and then treated with XFP. The aggravating action of SD on CIA rats and the efficacy of XFP were evaluated using AI scores, H&E staining of the joint, and level of serum anti–collagen type II antibody (Col II Ab). Bone destruction was assessed by micro-CT and TRACP staining. In addition, flow cytometry, qRT-PCR, and ELISA were used to evaluate gut mucosal immunity. Moreover, metagenomic sequencing was used to determine the distribution and function of the gut microbiota.

Results

Compared with that in CIA rats, bone destruction in SD-CIA rats was aggravated, as manifested by increased AI scores, more severe joint pathological changes and radiological damage, and increased number of osteoclasts (OCs) in the ankle joint. Meanwhile, the proportion of Tregs/Th17 cells was biased toward Th17 cells in Peyer’s patches. Furthermore, the gene levels of TNF-α, IL-1β, IL-6, and IL-17 were increased. In contrast, the expression of IL-10 and sIgA was decreased in the jejunum and ileum. XFP treatment improved bone damage and intestinal mucosal immune disorders compared with the SD-CIA group. In addition, the distribution and function of the gut microbiota were altered in the SD-CIA group. After XFP treatment, the community and function of the gut microbiota were regulated, manifested as increased abundance of several Lactobacillus species, such as L. acidophilus, which regulates the intestinal Tregs/Th17 cells and quorum sensing pathways, followed by promoting probiotic adhesion to the intestines.

Conclusion

SD can aggravate bone destruction in CIA rats. Compound XFP may attenuate bone destruction in SD-CIA rats by regulating the intestinal microenvironment. One of the mechanisms is the cross-talk between sIgA secretion regulated by intestinal mucosal Tregs and Th17 cells and adhesion of Lactobacillus mediated by quorum sensing.

Immuno-modulatory effect of probiotic E. coli Nissle 1917 in polarized human colonic cells against Campylobacter jejuni infection

Campylobacter jejuni is among the leading causes of bacterial foodborne illness. Poultry is the major reservoir and source of human campylobacteriosis. Currently, there is no effective and practical method to decrease C. jejuni colonization in chickens or to reduce human infections. Additionally, antibiotic-resistant infections pose a serious public health concern; therefore, antibiotic-alternative approaches are needed to reduce transmission of C. jejuni including resistant bacteria from chickens to humans. Here, we evaluated the effect of E. coli Nissle 1917 (EcN) on innate responses of polarized HT-29 cells and consequently on C. jejuni 81176 infections in HT-29 cells. Pre-treatment of HT-29 cells with EcN for 4 h had a significant effect on the invasion of different C. jejuni strains (2 h post-infection) (P < .05) and no intracellular C. jejuni (24 h post-infection) were recovered. To further understand how EcN mediates its impact on C. jejuni's survival inside the cells, we used Human Antibacterial RT² Profiler^TM PCR arrays to profile gene expression in HT-29 cells after treatment with EcN with or without C. jejuni 81-176 infection. Our results suggest that pre-treatment of the HT-29 cells with EcN induced the anti-inflammatory cytokines and activated the anti-apoptotic Akt signaling which likely to protect the cells against the proinflammatory and apoptosis responses induced by C. jejuni. EcN also positively affected the expression of genes involved in cellular maintenance, growth, development, and proliferation. Further, EcN modulated the expression of genes involved in protective innate immunity, such as TLRs, ERK1/2, p38 MAPK, Ap1, JNK, IL1B, IL17A, and NF-κB signaling.

Evaluation of Immunomodulatory Activities of the Heat-Killed Probiotic Strain Lactobacillus casei IMAU60214 on Macrophages In Vitro

Most Lactobacillus species have beneficial immunological (“immunoprobiotic”) effects in the host. However, it is unclear how probiotic bacteria regulate immune responses. The present study investigated the effects of heat-killed Lactobacillus casei IMAU60214 on the activity of human monocyte-derived macrophages (MDMs). Human MDMs were treated with heat-killed L. casei at a ratio (bacteria/MDM) of 50:1, 100:1, 250:1, and 500:1, and then evaluated for the following: NO production, by Griess reaction; phagocytosis of FITC-labeled Staphylococcus aureus particles; cytokine secretion profile (tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-12p70, IL-10, and transforming growth factor (TGF)-β) by ELISA; and costimulatory molecule (CD80 and CD86) surface expression, by flow cytometry. Heat-killed L. casei IMAU60214 enhanced phagocytosis, NO production, cytokine release, and surface expression of CD80 and CD86 in a dose-dependent manner. All products were previously suppressed by pretreatment with a Toll-like receptor 2 (TLR2)-neutralizing antibody. Overall, our findings suggest that this probiotic strain promotes an M1-like pro-inflammatory phenotype through the TLR2 signaling pathway. These effects on macrophage phenotype help explain the probiotic efficacy of Lactobacillus and provide important information for the selection of therapeutic targets and treatments compatible with the immunological characteristics of this probiotic strain.

Uromodulin-SlpA binding dictates Lactobacillus acidophilus uptake by intestinal epithelial M cells

Bacterial access to the gut immune system is a crucial process to promote host immune responses. The probiotic L-92 strain of Lactobacillus acidophilus exerts anti-allergic immunomodulatory effects upon oral administration in mice. Here, we show that microfold cells (M cells) are responsible for L-92 internalization for evoking L-92-mediated immune responses. L-92 specifically bound to uromodulin, a glycosylphosphatidylinositol-anchored protein expressed exclusively on M cells among intestinal epithelial cells. Internalization of L-92 into M cells was significantly reduced in uromodulin-deficient (Umod-/-) mice compared to Umod+/+ mice. Furthermore, the binding of L-92 to uromodulin was significantly decreased after removal of surface layer protein A (SlpA) from the bacteria. Our study thus revealed a crucial role of uromodulin on the M-cell surface for the uptake of SlpA-positive lactic acid bacteria into M cells, possibly leading to subsequent delivery of the bacteria to dendritic cells closely associated with M cells for immunomodulation. Our study also shed light on the possibility that SlpA and uromodulin could be used as vehicle and target, respectively, for efficient mucosal vaccine delivery.