Hiroki Nakano

Critical Roles of Myeloid Differentiation Factor 88-Dependent Proinflammatory Cytokine Release in Early Phase Clearance of Listeria monocytogenes in Mice

Listeria monocytogenes (LM), a facultative intracellular Gram-positive bacterium, often causes lethal infection of the host. In this study we investigated the molecular mechanism underlying LM eradication in the early phase of infection. Upon infection with LM, both IL-12 and IL-18 were produced, and then they synergistically induced IFN-γ production, leading to normal LM clearance in the host. IFN-γ knockout (KO) mice were highly susceptible to LM infection. IL-12/IL-18 double knockout mice were also highly susceptible. Their susceptibility was less than that of IFN-γ KO mice, but more than that of single IL-12 or IL-18 KO mice. Mice deficient in myeloid differentiation factor 88 (MyD88), an essential adaptor molecule used by signal transduction pathways of all members of the Toll-like receptor (TLR) family, showed an inability to produce IL-12 and IFN-γ following LM infection and were most susceptible to LM. Furthermore, MyD88-deficient, but not IFN-γ-deficient, Kupffer cells could not produce TNF-α in response to LM in vitro, indicating the importance of MyD88-dependent TNF-α production for host defense. As TLR2 KO, but not TLR4 KO, mice showed partial impairment in their capacity to produce IL-12, IFN-γ, and TNF-α, TLR2 activation partly contributed to the induction of IL-12-mediated IFN-γ production. These results indicated a critical role for TLRs/MyD88-dependent IL-12/TNF-α production and for IL-12- and IL-18-mediated IFN-γ production in early phase clearance of LM.

Caspase-1-Independent, Fas/Fas Ligand–Mediated IL-18 Secretion from Macrophages Causes Acute Liver Injury in Mice

IL-18, produced as a biologically inactive precursor, is processed by caspase-1 in LPS-activated macrophages. Here, we investigated caspase-1-independent processing of IL-18 in Fas ligand (FasL)-stimulated macrophages and its involvement in liver injury. Administration of Propionibacterium acnes (P. acnes) upregulated functional Fas expression on macrophages in an IFNgamma-dependent manner, and these macrophages became competent to secrete mature IL-18 upon stimulation with FasL. This was also the case for caspase-1-deficient mice. Administration of recombinant soluble FasL (rFasL) after P. acnes priming induced comparable elevation of serum IL-18 in parallel with elevated serum liver enzyme levels. However, liver injury was not induced in IL-18-deficient mice after rFasL administration. These results indicate a caspase-1-independent pathway of IL-18 secretion from FasL-stimulated macrophages and its critical involvement in FasL-induced liver injury.

Plasmodium berghei infection in mice induces liver injury by an IL-12- and Toll-like receptor/myeloid differentiation factor 88-dependent mechanism

Malaria, caused by infection with Plasmodium spp., is a life cycle-specific disease that includes liver injury at the erythrocyte stage of the parasite. In this study, we have investigated the mechanisms underlying Plasmodium berghei-induced liver injury, which is characterized by the presence of apoptotic and necrotic hepatocytes and dense infiltration of lymphocytes. Although both IL-12 and IL-18 serum levels were elevated after infection, IL-12-deficient, but not IL-18-deficient, mice were resistant to liver injury induced by P. berghei. Neither elevation of serum IL-12 levels nor liver injury was observed in mice deficient in myeloid differentiation factor 88 (MyD88), an adaptor molecule shared by Toll-like receptors (TLRs). These results demonstrated a requirement of the TLR-MyD88 pathway for induction of IL-12 production during P. berghei infection. Hepatic lymphocytes from P. berghei-infected wild-type mice lysed hepatocytes from both uninfected and infected mice. The hepatocytotoxic action of these cells was blocked by a perforin inhibitor but not by a neutralizing anti-Fas ligand Ab and was up-regulated by IL-12. Surprisingly, these cells killed hepatocytes in an MHC-unrestricted manner. However, CD1d-deficient mice that lack CD1d-restricted NK T cells, were susceptible to liver injury induced by P. berghei. Collectively, our results indicate that the liver injury induced by P. berghei infection of mice induces activation of the TLR-MyD88 signaling pathway which results in IL-12 production and activation of the perforin-dependent cytotoxic activities of MHC-unrestricted hepatic lymphocytes.

Lipopolysaccharide-Induced IL-18 Secretion from Murine Kupffer Cells Independently of Myeloid Differentiation Factor 88 That Is Critically Involved in Induction of Production of IL-12 and IL-1β

IL-18, produced as biologically inactive precursor, is secreted from LPS-stimulated macrophages after cleavage by caspase-1. In this study, we investigated the mechanism underlying caspase-1-mediated IL-18 secretion. Kupffer cells constantly stored IL-18 and constitutively expressed caspase-1. Inhibition of new protein synthesis only slightly reduced IL-18 secretion, while it decreased and abrogated their IL-1β and IL-12 secretion, respectively. Kupffer cells deficient in Toll-like receptor (TLR) 4, an LPS-signaling receptor, did not secrete IL-18, IL-1β, and IL-12 upon LPS stimulation. In contrast, Kupffer cells lacking myeloid differentiation factor 88 (MyD88), an adaptor molecule for TLR-mediated-signaling, secreted IL-18 without IL-1β and IL-12 production in a caspase-1-dependent and de novo synthesis-independent manner. These results indicate that MyD88 is essential for IL-12 and IL-1β production from Kupffer cells while their IL-18 secretion is mediated via activation of endogenous caspase-1 without de novo protein synthesis in a MyD88-independent fashion after stimulation with LPS. In addition, infection with Listeria monocytogenes, products of which have the capacity to activate TLR, increased serum levels of IL-18 in wild-type and MyD88-deficient mice but not in caspase-1-deficient mice, whereas it induced elevation of serum levels of IL-12 in both wild-type and caspase-1-deficient mice but not in MyD88-deficient mice. Taken together, these results suggested caspase-1-dependent, MyD88-independent IL-18 release in bacterial infection.

Gastroduodenitis associated with ulcerative colitis

BackgroundUlcerative colitis (UC) is regarded as confined to the colorectum; however, there are several case reports showing upper gastrointestinal involvement. The aim of this study was to examine the prevalence and characteristics of gastroduodenitis associated with UC (GDUC).MethodsEsophagogastroduodenoscopy with biopsies was prospectively performed on 250 UC patients (134 men, 116 women; mean age, 42 years; 162 with colectomy, 163 with pancolitis). Criteria for GDUC were created on the basis of endoscopic and histological comparisons with non-UC controls, and the prevalence and characteristics were statistically analyzed.ResultsGDUC was defined endoscopically as friable mucosa (erosive or ulcerative mucosa with contact or spontaneous bleeding), granular mucosa (multiple white spots almost without a red halo), or, conditionally, multiple aphthae (multiple white spots surrounded by a red halo, clinically excluding other disorders such as Crohn’s disease). The prevalence of GDUC was 19/250 (7.6%). The clinical characteristics included more extensive colitis, lower dose of prednisolone, higher prevalence of pouchitis, and longer postoperative period. In our population, the presence of pancolitis and a lower dose of prednisolone were significant risk factors for developing GDUC in multivariate analysis.ConclusionsThe high prevalence of GDUC suggests that the gut inflammatory reaction in UC may not be restricted to the large intestine. Administered steroids might conceal GDUC, and more aggressive UC such as active pancolitis may be related to the development of GDUC.

Safety of One-Stage Restorative Proctocolectomy for Ulcerative Colitis

PURPOSEThe aim of this study was to compare clinical outcomes in patients with ulcerative colitis who underwent restorative proctocolectomy with and without diverting ileostomy.METHODSA series of 245 consecutive patients who underwent ileal pouch anal anastomosis with mucosectomy with an ultrasonically activated scalpel (harmonic scalpel) was studied. Of these patients, 92 patients had a diverting ileostomy and 150 selected patients did not. The decision for or against an ileostomy was made at the end of the operation.RESULTSTwelve patients (8 percent) in the group without ileostomy had pouch-related complications, which necessitated secondary ileostomy in five patients (3.3 percent). Intestinal obstruction developed in 17 patients (11.3 percent) who had no ileostomy and in 12 patients (13.0 percent) who underwent ileostomy. Two of 17 patients who had no ileostomy and 1 of 12 patients with ileostomy required laparotomy with division of adhesions, whereas the remaining patients responded to conservative measures. There were no significant differences in the incidence of postoperative complications after the initial operation between the two groups. In the group with ileostomy, the morbidity rate for ileostomy was 12.1 percent, and that for ileostomy closure was 18.7 percent. The total postoperative complication rate for the group with ileostomy was significant higher than that for the group without ileostomy.CONCLUSIONWe conclude that restorative proctocolectomy with mucosectomy by use of an ultrasonically activated scalpel and without diversion is a superior therapeutic choice for selected patients.

Incidence and therapeutic outcome of pouchitis for ulcerative colitis in Japanese patients.

Aim: The aim of this study was to examine the cumulative risk of pouchitis following restorative proctocolectomy for UC and FAP in Japanese patients, and to assess the response to medical treatment and its outcome. Patients and Methods: 521 patients with UC and 117 FAP patients underwent proctocolectomy and received a J-shaped IPAA at our department of surgery. We investigated these patients using PDAI for the diagnostic criteria of pouchitis. Results: Pouchitis occurred in only 32 UC patients (6.1%). The cumulative risk of developing pouchitis for a UC patient was 7% at 5 years after and 12% at 10 years after surgery. The medical treatment of acute pouchitis was usually oral metronidazole (250 mg twice daily) for 2 weeks or oral ciprofloxacin (200 mg thrice daily) in patients who could not tolerate metronidazole. Single episodes of pouchitis occurred in 21 patients (65.6%) and chronic or frequent relapses of pouchitis in 11 patients (34.4%). Three patients (9.4%) required re-ileostomy. Two patients (6.3%) required pouch excision. There were no patients with complicated dysplasia. Conclusion: The cumulative risk of pouchitis in Japanese UC patients is lower than that of western countries.

Postoperative Joint Symptoms: A Risk Factor for Pouchitis in Ulcerative Colitis Patients

Background: The prevalence and significance of joint symptoms appearing in patients with ulcerative colitis (UC) following a colectomy are unclear. Aim: We investigated the relationship between joint symptoms during steroid tapering following an ileal pouch-anal anastomosis (IPAA) and the cumulative risk for developing pouchitis. Patients and Methods: The medical records of 571 patients who underwent an IPAA with a mucosectomy were retrospectively reviewed to evaluate their joint symptoms. A diagnosis of pouchitis was obtained using the Pouchitis Disease Activity Index (PDAI) and the cumulative risk of pouchitis was estimated using a Kaplan-Meier life table analysis. Results: Joint symptoms during steroid tapering were reported by 126 (22.0%) of the UC patients and each of those had involvement of the small joints of the hand. The main symptoms were pain and stiffness, especially in the morning. The cumulative risk for developing pouchitis after 10 years was found to be 20% in patients who experienced joint symptoms during steroid tapering and 10% in those without those symptoms (p = 0.001). Conclusion: The presence of joint symptoms during steroid tapering is a significant risk factor for the development of pouchitis in patients who have undergone an IPAA for UC.

Postoperative enteroenteric intussusception in patients with Crohn’s disease: Report of two cases

Postoperative enteroenteric intussusception is a rare complication in adult patients with Crohn’s disease. We treated two patients with Crohn’s disease accompanied by an ileal obstruction, each of whom underwent an elective resection. In both, the upper left quadrant of the abdoment became progressively distended following ileocecal resection and each required surgical treatment after diagnosis of postoperative enteroenteric intussusception by abdominal computed tomography scanning, as the intussusception could not be reduced by conservative treatment. There were no Crohn’s lesions found in the intussuscepted specimens, and the condition was thought to have been caused by a segment of thickened and fibrotic intestine that had developed because of long-standing bowel dilatation from obstructive Crohn’s lesions. In one of the patients, the intussusceptum was irreducibly incarcerated and required a resection, whereas it was able to be manually reduced in the other.

Leukocyte removal therapy for ulcerative colitis does not affect postoperative complications

BackgroundWe investigated the incidence of postoperative complications in patients treated with or without preoperative leukocyte removal therapy (LRT).MethodsThe case notes of 387 patients with ulcerative colitis (UC) who underwent surgical intervention were retrospectively reviewed. One hundred nine patients were treated with LRT within 8 weeks before surgery (LRT group), and 278 had not received LRT since at least 8 weeks before surgery (without LRT group). We reviewed the postoperative complications according to type of initial operation.ResultsOf the patients who underwent an ileal J-pouch anal anastomosis (IPAA) without an ileostomy, 3 (6.5%) in the LRT group developed pouch-related complications (PRC), while 11 (7.5%) in the without LRT group developed PRC. The overall postoperative complication rates were 28.3% in the LRT group and 21.8% in the without LRT group. For patients who underwent an IPAA with an ileostomy, the overall rates of postoperative complications were 39.1% in the LRT group and 31.8% in the without LRT group. Among those undergoing a total colectomy, 33.3% in the LRT group and 18.2% in the without LRT group had postoperative complications. No statistically significant differences were demonstrated between the two groups with respect to postoperative complications.ConclusionsOur results suggest that preoperative LRT does not influence the rate of postoperative complications in UC patients.