Colonic innate immune defenses and microbiota alterations in acute swine dysentery.

Brachyspira hyodysenteriae, an etiologic agent of swine dysentery (SD), is known for causing colitis. Although some aspects of colonic defenses during infection have been described previously, a more comprehensive picture of the host and microbiota interaction in clinically affected animals is required. This study aimed to characterize multiple aspects of colonic innate defenses and microbiome factors in B. hyodysenteriae-infected pigs that accompany clinical presentation of hemorrhagic diarrhea. We examined colonic mucus barrier modifications, leukocyte infiltration, cathelicidin expression, as well as microbiome composition. We showed that B. hyodysenteriae infection caused microscopic hemorrhagic colitis with abundant neutrophil infiltration in the colonic lamina propria and lumen, with minor macrophage infiltration. Mucus hypersecretion with abundant sialylated mucus in the colon, as well as mucosal colonization by [Acetivibrio] ethanolgignens, Lachnospiraceae, and Campylobacter were pathognomonic of B. hyodysenteriae infection. These findings demonstrate that B. hyodysenteriae produces clinical disease through multiple effects on host defenses, involving alterations of mucosal innate immunity and microbiota. Given that B. hyodysenteriae is increasingly resistant to antimicrobials, this understanding of SD pathogenesis may lead to future development of non-antibiotic and anti-inflammatory alternative therapeutics.

Mucosal eosinophilic infiltration may be a characteristic of human intestinal spirochetosis.

BACKGROUND: Human intestinal spirochetosis (HIS) is an infectious disease of large intestines caused by Brachyspira species, and most HIS cases are asymptomatic or exhibit mild intestinal symptoms. The host reaction to HIS remains unclear, and we examined HIS-related mucosal inflammatory features histologically. METHODS: From the archival HIS cases in a single medical center, 24 endoscopically taken specimens from 14 HIS cases (male:female = 10:4; 28-73 yrs) were selected as not containing polypoid or neoplastic lesions. Stromal neutrophils, eosinophils, and mast cells, and intraepithelial neutrophils and eosinophils, (sNeu, sEo, sMast, iNeu, and iEo, respectively) were counted, and the presence or absence of lymphoid follicles/aggregates (LFs) was also examined. Association of the above inflammation parameters and spirochetal infection parameters (such as degrees of characteristic fringe distribution, of spirochetal cryptal invasion, and of spirochetal intraepithelial invasion) were also analysed. RESULTS: iNeu was observed in 29.2%, iEo in 58.3%, and LFs in 50.0% of the specimens. Maximal counts of sNeu, sEo, sMast, iNeu, and iEo averaged 8.4, 21.5, 6.0, 0.5 and 1.5, respectively. Strong correlation between the maximum counts of iNeu and iEo (p < 0.001, r = 0.81), and correlations between those of iEo and sNeu (p = 0.0012, r = 0.62) and between those of iEo and sEo (p = 0.026, r = 0.45) were observed. iNeu was influenced by fringe formation (p < 0.05) and spirochetal crypt involvement (p < 0.05). CONCLUSIONS: HIS was accompanied by inflammatory reactions, and among these, mucosal eosinophilic infiltration may be a central indicator and host reaction of HIS.

Doxycycline for Prevention of Spirochetal Infections: Status Report.

Important human infections caused by spirochetal microorganisms include Lyme disease, syphilis, leptospirosis, and tick-borne relapsing fever. Doxycycline prophylactic regimens have been shown to significantly reduce the risk for developing all of these infections in potentially exposed individuals, which is highly clinically relevant as no vaccines to prevent these infections in humans are currently available. Additional data, however, are needed to define more precisely the level of efficacy of the doxycycline prophylactic regimens, especially for Lyme disease and syphilis, infections that can be potentially prevented by a single 200-mg dose of doxycycline given within 72 hours postexposure.

An uncommon cause of chronic abdominal pain and diarrhea.

The intestinal spirochaetosis is defined as the presence of spirochetes on the colonic surface. We present the case of a 57-years-old male, with a history of 4-5 months of diffuse abdominal pain, watery diarrhoea due to this infection. The colonoscopy revealed a serpiginous ulcer in the cecum. The biopsy was positive for intestinal spirochaetosis. It is rare infection, more common among immunocompromised patients and HIV, with a faecal-oral transmission. Most cases are incidental findings in the endoscopic screening. In symptomatic patients the watery diarrhoea and non-specific abdominal pain are the most common symptoms. The macroscopic appearance on the colonoscopy is often normal or non-specific lesions can be identified. The diagnosis is based on the biopsy with haematoxylin and eosin and the confirmation can be made with a Warthin-Starry stain. In symptomatic patients the metronidazole is the preferred treatment option. Although it is rare infection, clinicians should be aware of it in patients with common gastrointestinal symptoms.

Hiding in Plain Sight: Colonic Spirochetosis in Humans.

In 1967, Harland and Lee made a startling discovery: in some humans, the colonic epithelium is covered with a "forest" of spirochetes (W. A. Harlan, and F. D. Lee, Br Med J 3:718-719, 1967, https://doi.org/10.1136/bmj.3.5567.718). In this issue of Journal of Bacteriology, Thorell et al. present a systematic analysis of the prevalence and diversity of the spirochetes Brachyspira aalborgi and Brachyspira pilosicoli in the human colon. These and prior studies provide avenues toward resolving important questions: what bacterial and host parameters contribute to this extensive colonization, and what impact does it have on human health?

Isolates from Colonic Spirochetosis in Humans Show High Genomic Divergence and Potential Pathogenic Features but Are Not Detected Using Standard Primers for the Human Microbiota.

Colonic spirochetosis, diagnosed based on the striking appearance in histological sections, still has an obscure clinical relevance, and only a few bacterial isolates from this condition have been characterized to date. In a randomized, population-based study in Stockholm, Sweden, 745 healthy individuals underwent colonoscopy with biopsy sampling. Of these individuals, 17 (2.3%) had colonic spirochetosis, which was associated with eosinophilic infiltration and a 3-fold-increased risk for irritable bowel syndrome (IBS). We aimed to culture the bacteria and perform whole-genome sequencing of the isolates from this unique representative population sample. From 14 out of 17 individuals with spirochetosis we successfully isolated, cultured, and performed whole-genome sequencing of in total 17 isolates, including the Brachyspira aalborgi type strain, 513A. Also, 16S analysis of the mucosa-associated microbiota was performed in the cases and nonspirochetosis controls. We found one isolate to be of the species Brachyspira pilosicoli; all remaining isolates were of the species Brachyspira aalborgi Besides displaying extensive genetic heterogeneity, the isolates harbored several mucin-degrading enzymes and other virulence-associated genes that could confer a pathogenic potential in the human colon. We also showed that 16S amplicon sequencing using standard primers for human microbiota studies failed to detect Brachyspira due to primer incompatibility.IMPORTANCE This is the first report of whole-genome analysis of clinical isolates from individuals with colonic spirochetosis. This characterization provides new opportunities in understanding the physiology and potentials of these bacteria that densely colonize the gut in the individuals infected. The observation that standard 16S amplicon primers fail to detect colonic spirochetosis may have major implications for studies searching for associations between members of the microbiota and clinical conditions such as irritable bowel syndrome (IBS) and should be taken into consideration in project design and interpretation of gastrointestinal tract microbiota in population-based and clinical settings.

[Immunohistochemical diagnosis of colonic spirochetosis with anti-treponema antibody in patients consulting for chronic diarrhea. Results of a prospective study conducted in 137 patients]. / Diagnostic immunohistochimique de la spirochétose colique avec l'anticorps anti-tréponème chez les patients consultant pour une diarrhée chronique. Résultats d'une étude prospective menée chez 137 patients.

AIM: To assess the incidence of colonic spirochetosis, diagnosed by immunohistochemical stain with anti-Treponema pallidum antibody, in a prospective study of colonic biopsies of patients presenting with chronic diarrhea. MATERIAL AND METHODS: From March 2017 to March 2018 the colonic biopsies of patients presenting with chronic diarrhea were stained with Hematoxylin Eosin and anti-Treponema pallidum antibody. The positive cases were also stained with Steiner stain. RESULTS: A total of 137 colonic biopsies were assessed and 3 cases were positive for immunohistochemical stain with anti-Treponema pallidum antibody (2% of the patients). One case was easy to diagnose with HE stain but the 2 other cases were not. The bacteria were stained with Steiner stain, but less easily seen than with the immunohistochemical stain. No patient was treated with antibiotics. DISCUSSION AND CONCLUSION: The colonic spirochetosis can be easily diagnosed by pathologists with immunohistochemical stain with anti-Treponema pallidum antibody. The bacteria are more easily diagnosed with immunohistochemical stain than with HE stain or Steiner stain. However, colonic spirochetosis is rarely diagnosed on colonic biopsies of patients presenting with chronic diarrhea (2% of the patients in our study). Due to the rarity of the entity, and the cost of immunohistochemical stain and the weak benefit for the patient (no patient in our study was treated with antibiotics for colonic spirochetosis) we cannot advise to perform systematic immunohistochemical stain with anti-Treponema pallidum antibody in all the colonic biopsies of patients presenting with chronic diarrhea.

Flagellar motility of the pathogenic spirochetes.

Bacterial pathogens are often classified by their toxicity and invasiveness. The invasiveness of a given bacterium is determined by how capable the bacterium is at invading a broad range of tissues in its host. Of mammalian pathogens, some of the most invasive come from a group of bacteria known as the spirochetes, which cause diseases, such as syphilis, Lyme disease, relapsing fever and leptospirosis. Most of the spirochetes are characterized by their distinct shapes and unique motility. They are long, thin bacteria that can be shaped like flat-waves, helices, or have more irregular morphologies. Like many other bacteria, the spirochetes use long, helical appendages known as flagella to move; however, the spirochetes enclose their flagella in the periplasm, the narrow space between the inner and outer membranes. Rotation of the flagella in the periplasm causes the entire cell body to rotate and/or undulate. These deformations of the bacterium produce the force that drives the motility of these organisms, and it is this unique motility that likely allows these bacteria to be highly invasive in mammals. This review will describe the current state of knowledge on the motility and biophysics of these organisms and provide evidence on how this knowledge can inform our understanding of spirochetal diseases.

Borrelia burgdorferi CheY2 Is Dispensable for Chemotaxis or Motility but Crucial for the Infectious Life Cycle of the Spirochete.

The requirements for bacterial chemotaxis and motility range from dispensable to crucial for host colonization. Even though more than 50% of all sequenced prokaryotic genomes possess at least one chemotaxis signaling system, many of those genomes contain multiple copies of a chemotaxis gene. However, the functions of most of those additional genes are unknown. Most motile bacteria possess at least one CheY response regulator that is typically dedicated to the control of motility and which is usually essential for virulence. Borrelia burgdorferi appears to be notably different, in that it has three cheY genes, and our current studies on cheY2 suggests that it has varied effects on different aspects of the natural infection cycle. Mutants deficient in this protein exhibit normal motility and chemotaxis in vitro but show reduced virulence in mice. Specifically, the cheY2 mutants were severely attenuated in murine infection and dissemination to distant tissues after needle inoculation. Moreover, while ΔcheY2 spirochetes are able to survive normally in the Ixodes ticks, mice fed upon by the ΔcheY2-infected ticks did not develop a persistent infection in the murine host. Our data suggest that CheY2, despite resembling a typical response regulator, functions distinctively from most other chemotaxis CheY proteins. We propose that CheY2 serves as a regulator for a B. burgdorferi virulence determinant that is required for productive infection within vertebrate, but not tick, hosts.

Human intestinal spirochetosis in Japanese patients aged less than 20 years: Histological analysis of colorectal biopsy and surgical specimens obtained from 479 patients.

Human intestinal spirochetosis (HIS) is a condition in which spirochetes attach to and colonize the colorectal epithelium. To our knowledge, no comprehensive studies of HIS in young patient have been published in a developed country. This study aimed to determine the incidence and clinicopathological manifestations of HIS in Japanese patients aged less than 20 years. We retrospectively reviewed 3605 biopsy and 92 surgical specimens obtained from 479 patients admitted to Shinshu University Hospital between 1997 and 2014. All slides were reviewed independently by two pathologists to confirm the histological presence of spirochetes. Among 387 patients who underwent biopsy, the most common pathologic diagnosis was ulcerative colitis (12.6%, n = 49). Additionally, about half of the biopsy specimens showed non-specific, mildly inflamed mucosa (50.6%, n = 196); only one of these cases was HIS. On the other hand, among the surgical specimens, we found no cases of HIS. We concluded that the incidence of HIS in Japanese young patients was 0.2% (1/479 cases). The incidence of HIS in Japanese young patients was very low, and one HIS case was associated with colitis with abdominal pain.

Clinical significance of human intestinal spirochetosis: a retrospective study.

The clinical and pathological features of human intestinal spirochetosis (HIS) are not well known. Here we report 55 patients with HIS who were diagnosed at our institution during the past 5 years. Seven patients presented with symptoms such as abdominal pain or diarrhea, while the others were incidentally diagnosed during screening colonoscopy. Most patients had non-specific endoscopic findings, including intestinal edema or erosion. The diagnosis of HIS was histologically confirmed via hematoxylin and eosin staining, periodic acid-Schiff staining, and/or immunohistochemistry using anti-Treponema pallidum antibody. Among the 55 patients, five were diagnosed with diseases other than HIS (amoebic colitis, three;ulcerative colitis, one). Sixteen patients were treated with either amoxicillin or metronidazole;only metronidazole proved to be effective. The clinical significance of asymptomatic HIS remains unknown. Some case reports suggest a risk for increased severity in patients with immunodeficiency and/or sexually transmitted diseases. Therefore, aggressive treatment for HIS should be considered, particularly in high-risk patients.

Treponema denticola invasion into human gingival epithelial cells.

Host cell invasion is important for periodontal pathogens in evading host defenses and spreading into deeper areas of the periodontal tissue. Treponema denticola has been implicated in a number of potentially pathogenic processes, including periodontal tissue penetration. Here we tested the ability of T. denticola strains to invade human gingival epithelial cells (HGEC). After 2 h infection, intracellular location of T. denticola cells was confirmed by confocal laser scanning microscopy (CLSM). Results from an antibiotic protection assay following [(3)H]uridine labeling indicated that invasion efficiency reached a maximum at 2 h after infection. Internalized T. denticola cells were still observed in HGEC at 24 h by CLSM. A dentilisin deficient mutant exhibited significantly decreased invasion (p < 0.05) compared with the wild-type strain. In inhibition assays, phenylmethylsulfonyl fluoride and metabolic inhibitors such as methyl-ß-cyclodextrin and staurosporine significantly reduced T. denticola invasion. Under CLSM, T. denticola colocalized with GM-1 ganglioside-containing membrane microdomains in a cholesterol-dependent manner. These results indicated that T. denticola has the ability to invade into and survive within HGECs. Dentilisin activity of T. denticola and lipid rafts on HGEC appear to play important roles in this process.

Clinicopathologic study of intestinal spirochetosis in Japan with special reference to human immunodeficiency virus infection status and species types: analysis of 5265 consecutive colorectal biopsies.

BACKGROUND: Previous studies reported that the incidence of intestinal spirochetosis was high in homosexual men, especially those with Human Immunodeficiency Virus infection. The aim of the present study was to clarify the clinicopathological features of intestinal spirochetosis in Japan with special reference to Human Immunodeficiency Virus infection status and species types. METHODS: A pathology database search for intestinal spirochetosis was performed at Tokyo Metropolitan Cancer and Infectious Disease Center Komagome Hospital between January 2008 and October 2011, and included 5265 consecutive colorectal biopsies from 4254 patients. After patient identification, a retrospective review of endoscopic records and clinical information was performed. All pathology slides were reviewed by two pathologists. The length of the spirochetes was measured using a digital microscope. Causative species were identified by polymerase chain reaction. RESULTS: Intestinal spirochetosis was diagnosed in 3 out of 55 Human Immunodeficiency Virus-positive patients (5.5%). The mean length of intestinal spirochetes was 8.5 µm (range 7-11). Brachyspira pilosicoli was detected by polymerase chain reaction in all 3 patients. Intestinal spirochetosis was also diagnosed in 73 out of 4199 Human Immunodeficiency Virus-negative patients (1.7%). The mean length of intestinal spirochetes was 3.5 µm (range 2-8). The species of intestinal spirochetosis was identified by polymerase chain reaction in 31 Human Immunodeficiency Virus-negative patients. Brachyspira aalborgi was detected in 24 cases (78%) and Brachyspira pilosicoli in 6 cases (19%). Both Brachyspira aalborgi and Brachyspira pilosicoli were detected in only one Human Immunodeficiency Virus-negative patient (3%). The mean length of Brachyspira aalborgi was 3.8 µm, while that of Brachyspira pilosicoli was 5.5 µm. The length of Brachyspira pilosicoli was significantly longer than that of Brachyspira aalborgi (p < 0.01). The lengths of intestinal spirochetes were significantly longer in Human Immunodeficiency Virus-positive patients than in Human Immunodeficiency Virus-negative patients (p < 0.05). CONCLUSIONS: The incidence of intestinal spirochetosis was slightly higher in Human Immunodeficiency Virus-positive patients than in Human Immunodeficiency Virus-negative patients. However, no relationship was found between the Human Immunodeficiency Virus status and intestinal spirochetosis in Japan. Brachyspira pilosicoli infection may be more common in Human Immunodeficiency Virus-positive patients with intestinal spirochetosis than in Human Immunodeficiency Virus-negative patients with intestinal spirochetosis.

Human intestinal spirochetosis: right-side preference in the large intestine.

Human intestinal spirochetosis (HIS) is a colorectal bacterial infection, and its clinicopathologic features remain unclear. The aim of this study was to examine its characteristics. We histologically reviewed paraffin-embedded section slides made in 2001, 2006, and 2011 at a single institution in Japan. Cases histologically exhibiting a distinct fringe formation were considered to have HIS. Information was obtained from pathology request forms. We identified 85 HIS cases among 4930 patients (7 cases [0.5%) in 2001, 29 [1.7%] in 2006, and 49 [2.8%] in 2011]. Gastrointestinal symptoms were observed in 7.1% of HIS cases. Human intestinal spirochetosis was more frequent in the right-side large intestine than in the left side. Among 224 samples from HIS cases, conventional (tubular, tubulovillous, and villous) adenomas were found in 148 samples. These adenomas were more frequent in the right side than in the left side, although neither their size nor morphology differed between the sides. Histopathologic evaluation suggested a year-upon-year increasing prevalence of HIS in Japan. A small number exhibited gastrointestinal symptoms. Both histologic sign of HIS and conventional adenomas were more frequent in the right-side large intestine. Therefore, a right-side preference may be a characteristic of HIS.