Endoscopic-assisted Surgical Removal of Infected Interosseous Wires 40 Years After Mandibular Surgery.

We demonstrate a highly reliable minimally invasive treatment for removal of residual wire from the mandible. The patient was a 55-year-old Japanese man who was referred to our department for a fistula in his submental area. The patient had undergone open reduction and fixation with wires for mandibular fractures (left parasymphysis, right angle fracture) more than 40 years prior and mandibular tooth extraction and drainage 6 months prior. Minimally invasive endoscopy-assisted wire removal surgery was performed under general anesthesia with good visualization in a narrow surgical field. Bone resection was minimized using an ultrasonic cutting instrument with a wide choice of tip shapes. The use of endoscopy with ultrasonic cutting tools makes it possible to effectively utilize narrow surgical fields with a small skin incision and minimal bone cutting. The advantages and disadvantages of the newer endoscopic systems in oral and maxillofacial surgical units are discussed.

Immunomodulatory effects of D-allose on cytokine production by plasmacytoid dendritic cells.

D-Allose is classified as a 'rare sugar,' i.e., part of the group of monosaccharides that are present in low quantities in the natural world. D-Allose has been demonstrated to exert many physiological functions. The effects of the rare sugars on immune responses are largely unexplored. Here, we investigated the physiological effects of D-allose on murine dendritic cells' cytokine production. When plasmacytoid dendritic cells (pDCs) were stimulated with a Toll-like receptor 7 (TLR7) ligand, a single-stranded RNA (ssRNA), or a TLR9 ligand, CpG DNA, in the medium containing D-allose, the productions of both interferon-alpha (IFN-α) and interleukin (IL)-12p40 were severely decreased. In contrast, a normal production of these cytokines was observed when pDCs were stimulated with other TLR7 ligands, an imidazoquinoline, or a guanosine analog. In contrast to the pDCs, conventional dendritic cells (cDCs) produced IL-12p40 and tumor necrosis factor-alpha (TNF-α) in response to an imidazoquinoline or CpG DNA even though D-allose was present in the medium. D-Allose did not induce pDC death, and not inhibit the endocytic uptake of fluorophore-labeled CpG DNA into pDCs. These results suggested that D-allose exerts its inhibitory effects after CpG DNA is internalized. We analyzed the TLR7/9 signal-induced activation of downstream signaling molecules in pDCs and observed that when pDCs were stimulated with a ssRNA or CpG DNA, the phosphorylation status of the MAPK family, which includes Erk1/2, JNK/SAPK, and p38 MAPK, was attenuated in the presence of D-allose compared to D-glucose controls. The stimulation of pDCs with an imidazoquinoline induced a strong phosphorylation of these MAPK family members even in the presence of D-allose. These findings reveal that D-allose can inhibit the cytokine production by pDCs stimulated with ssRNA or CpG DNA via an attenuation of the phosphorylation of MAPK family members.

Oral microorganisms and bloodstream infection in allogeneic hematopoietic stem cell transplantation.

OBJECTIVES: We aimed to compare oral and pathogenic microorganisms in bloodstream infections (BSIs) in allogeneic hematopoietic stem cell transplantation (allo-HSCT). We also investigated the relationship between BSIs and oral mucositis to identify the ratio of BSIs caused by oral microorganisms and the pathogenic microorganisms involved. MATERIALS AND METHODS: We collected data on BSIs in 96 patients who underwent allo-HSCT in our institute between April 2009 and December 2019, including BSI pathogens isolated from blood cultures (BBSIs) and microorganisms isolated from washing the oral cavity with sterile distilled water. Oral microorganisms obtained at the onset of BSI (OBSIs) and during allo-HSCT (OSCTs) were defined as isolates collected during the week of blood culturing. Study entry was limited to samples collected up to 1 month after allo-HSCT without BSI. When the BBSI and OBSI were the same, we considered the oral microorganism to have caused the BSI. RESULTS: The incidence rate of BSIs was 27%, and the predominant microorganism was coagulase-negative Staphylococci. Normal bacterial flora were decreased to 15.8% in OBSIs and 25.5% in OSCTs. The distribution of microorganisms without normal bacterial flora showed significant difference between BBSIs and OSCTs (p < 0.05). Oral mucositis was found in 72.9%, and BSI caused by oral microorganisms occurred in 46.2% of BSIs in allo-HSCT patients. CONCLUSION: The distribution of microorganisms obtained from blood in patients with BSI during allo-HSCT was found to be similar to that of microorganisms from oral cultures. CLINICAL RELEVANCE: Oral microorganism monitoring may be able to predict BSI during allo-HSCT.

Involvement of the γ Isoform of cPLA2 in the Biosynthesis of Bioactive N-Acylethanolamines.

Arachidonylethanolamide (anandamide) acts as an endogenous ligand of cannabinoid receptors, while other N-acylethanolamines (NAEs), such as palmitylethanolamide and oleylethanolamide, show analgesic, anti-inflammatory, and appetite-suppressing effects through other receptors. In mammalian tissues, NAEs, including anandamide, are produced from glycerophospholipid via N-acyl-phosphatidylethanolamine (NAPE). The ɛ isoform of cytosolic phospholipase A2 (cPLA2) functions as an N-acyltransferase to form NAPE. Since the cPLA2 family consists of six isoforms (α, ß, γ, δ, ɛ, and ζ), the present study investigated a possible involvement of isoforms other than ɛ in the NAE biosynthesis. Firstly, when the cells overexpressing one of the cPLA2 isoforms were labeled with [14C]ethanolamine, the increase in the production of [14C]NAPE was observed only with the ɛ-expressing cells. Secondly, when the cells co-expressing ɛ and one of the other isoforms were analyzed, the increase in [14C]N-acyl-lysophosphatidylethanolamine (lysoNAPE) and [14C]NAE was seen with the combination of ɛ and γ isoforms. Furthermore, the purified cPLA2γ hydrolyzed not only NAPE to lysoNAPE, but also lysoNAPE to glycerophospho-N-acylethanolamine (GP-NAE). Thus, the produced GP-NAE was further hydrolyzed to NAE by glycerophosphodiesterase 1. These results suggested that cPLA2γ is involved in the biosynthesis of NAE by its phospholipase A1/A2 and lysophospholipase activities.

The mechanism of action of Spi-B in the transcriptional activation of the interferon-α4 gene.

Plasmacytoid dendritic cells (pDCs) are characterized by an exclusive expression of nucleic acid sensing Toll-like receptor 7 (TLR7) and TLR9, and production of high amounts of type I interferon (IFN) in response to TLR7/9 signaling. This function is crucial for both antiviral immunity and the pathogenesis of autoimmune diseases. An Ets family transcription factor, i.e., Spi-B (which is highly expressed in pDCs) is required for TLR7/9 signal-induced type I IFN production and can transactivate IFN-α promoter in synergy with IFN regulatory factor-7 (IRF-7). Herein, we analyzed how Spi-B contributes to the transactivation of the Ifna4 promoter. We performed deletion and/or mutational analyses of the Ifna4 promoter and an electrophoretic mobility shift assay (EMSA) and observed an Spi-B binding site in close proximity to the IRF-7 binding site. The EMSA results also showed that the binding of Spi-B to the double-stranded DNA probe potentiated the recruitment of IRF-7 to its binding site. We also observed that the association of Spi-B with transcriptional coactivator p300 was required for the Spi-B-induced synergistic enhancement of the Ifna4 promoter activity by Spi-B. These results clarify the molecular mechanism of action of Spi-B in the transcriptional activation of the Ifna4 promoter.

D-Tagatose Effectively Reduces the Number of Streptococcus mutans and Oral Bacteria in Healthy Adult Subjects: A Chewing Gum Pilot Study and Randomized Clinical Trial.

We examined the effect of D-Tagatose on the growth of oral bacteria including Streptococcus mutans (S. mutans). Saliva collected from 10 healthy volunteers was plated on BHI medium (to culture total oral bacteria) and MBS medium (to culture S. mutans, specifically). Agar plates of BHI or MBS containing xylitol or D-Tagatose were cultured under aerobic or anaerobic conditions. We then counted the number of colonies. In BHI plates containing D-Tagatose, a complete and significant reduction of bacteria occurred under both aerobic and anaerobic conditions. In MSB medium, significant reduction of S. mutans was also observed. We then performed a doubleblind parallel randomized trial with 19 healthy volunteers. They chewed gum containing xylitol, D-Tagatose, or both for 4 weeks, and their saliva was collected weekly and plated on BHI and MSB media. These plates were cultured under anaerobic conditions. Total bacteria and S. mutans were not effectively reduced in either the D-Tagatose or xylitol gum group. However, S. mutans was significantly reduced in volunteers chewing gum containing both D-Tagatose and xylitol. Thus, D-Tagatose inhibited the growth of S. mutans and many types of oral bacteria, indicating that D-Tagatose intake may help prevent dental caries, periodontitis, and many oral diseases.

Fusuma Sliding Flap for Lip Reconstruction of Lower Lip Cancer.

Lower lip cancer is typically treated with surgical excision, and this frequently results in a large defect and severe aesthetic problems. Local flap reconstruction is suitable for restoring appearance and function, and it causes less surgical stress than a vascularized free flap. The Fusuma sliding flap is a local flap technique introduced by Kasai et al in 2008. Here, the authors report their use of this method for lip reconstruction in a 94-year-old Japanese female after the removal of a cancerous mass.

Treatment outcomes of adjunctive teriparatide therapy for medication-related osteonecrosis of the jaw (MRONJ): A multicenter retrospective analysis in Japan.

BACKGROUND: Therapeutic strategies for patients with medication-related osteonecrosis of the jaw (MRONJ) remain controversial. The aim of the present study was to clarify the effectiveness and safety of teriparatide therapy in Japanese MRONJ patients based on a large number of case series with a multicenter retrospective analysis. PATIENTS AND METHODS: Between January 2012 and December 2016, 29 patients who were diagnosed with MRONJ at 10 hospitals were treated with teriparatide. The medical records of these patients were retrospectively reviewed to assess the efficacy and safety of teriparatide therapy for MRONJ patients. RESULTS: Adverse events occurred in 17.2% of patients (5/29). One patient developed severe arthralgia and discontinued teriparatide therapy after 12 days, while others continued the treatment. Among 29 patients, the median period of administration of teriparatide was 14.0 months (range, 0.3-26 months), and treatment outcomes were evaluated as effective in 75.9% of patients with complete resolution in 65.5%. Among patients treated with oral bisphosphonates (BPs), 83.3% were effectively treated with teriparatide and 40% with intravenous BPs. The oral administration of BPs was associated with successful treatment outcomes with teriparatide (p = 0.062). CONCLUSIONS: Teriparatide therapy has potential as an effective treatment option for MRONJ.

Bone metabolism of the jaw in response to bisphosphonate: a quantitative analysis of bone scintigraphy images.

We examined the changes in the bone metabolism of the jaw in response to BP treatment, and we used bone SPECT-CT to analyze the site-specific bone metabolism between the jaw and other sites of bone. We compared the changes in the bone metabolism of each part of bone in response to BP treatment by performing a quantitative analysis of bone scintigraphy images between patients treated with low-dose BP for osteoporosis (LBP group; n = 17), those treated with high-dose BP for metastatic bone tumor (HBP group; n = 11), and patients with other oral disease who required bone scintigraphy, with no history of BP treatment (control group; n = 40). The study endpoint was the mean standardized uptake value (SUV) of the uptake of Tc-99 m methylene diphosphonate (MDP) in each group. The mean SUVs of the HBP group were significantly lower at the axial bone of the cervical vertebra, thoracic vertebra, sternum, and rib compared to those of the LBP and control groups. The LBP group's mean SUV was significantly higher at the temporal bone, the anodontia part of the alveolar bone in maxilla, the vital teeth part of alveolar bone in the mandible, and the temporomandibular joint. There was no significant difference among the three groups at the mandibular angle and mandibular ramus. Our analyses revealed that the bone metabolism of the jaw and temporal bone in the BP-treated patients was enhanced, and no suppression of bone remodeling in the jaw by BP was observed.

Assessment of Simultaneous Surgery for Odontogenic Sinusitis: Endoscopic Sinus Surgery With Endoscopic Apicoectomy.

Odontogenic sinusitis (OS) is a disease commonly encountered by otolaryngologists and oral surgeons. There is currently no standard consensus for the management of the causative teeth of OS, and the therapeutic outcomes of endodontic surgery remain unclear. The authors herein report the outcomes of simultaneous surgery for OS, endoscopic sinus surgery (ESS) with endoscopic apicoectomy. Twenty-one OS patients who underwent ESS were included in the intent-to-treat population. Eleven patients who simultaneously underwent endoscopic apicoectomy were included as the study group, and another 10 patients who were subjected to the extraction of the causative teeth preceding or during surgery were included as the control group. The postoperative tooth course after surgery in the study group was assessed as the primary outcome by periodic radiographs. The postoperative sinus course was compared between the 2 groups as the secondary outcome. Seventeen teeth were subjected to endoscopic apicoectomy concurrently with ESS, and the treatment success rate for periapical lesions was 94.1% (16 out of 17 teeth), which was consistent with previously reported outcomes for endodontic microsurgery. Ten of 11 patients (90.9%) had good postoperative sinus courses, and the mean wound-healing period of the sinus mucosa was 6.9 ±â€Š3.5 weeks. These results were not significantly different from those obtained for the control group (90% and 6.1 ±â€Š3.2 weeks). This surgical procedure may contribute to the preservation of causative teeth without having an impact on the successful treatment of sinusitis. A comprehensive surgical approach by otolaryngologists and oral surgeons is desirable for the treatment of OS.

Frontal Bone Fracture Patterns Suggesting Involvement of Optic Canal Damage.

PURPOSE: Fracture of the frontal bone can be accompanied by damage to the optic canal. The present study uses finite element analysis to identify fracture patterns, suggesting the involvement of the optic canal. METHODS: Ten finite-element skull models were generated from computer tomography data of 10 persons. Then, dynamic analyses simulating collision of a 2-cm-radius brass ball to 6 regions on the frontal bone in the 10 models were performed. Fracture patterns presented by the frontal bone in the 60 experiments were observed, and all those involving the optic canal were selected. Commonalities of the selected fracture patterns were identified. RESULTS: Fracture of the optic canal was observed in 9 of the 60 patients. In all 9 patients, fracture existed on the anterior and posterior walls of the frontal sinus and on the superior orbital wall. CONCLUSION: When the anterior and posterior walls of the frontal sinus and the superior orbital wall are all broken, the optic canal is highly likely to be involved in the damage. When this pattern is observed in emergency examination, preventive decompression of the optic nerve should be considered to avoid potential occurrence of blindness.

The utility of bone scintigraphy in the assessment of mandibular metabolism during long-term bisphosphonate administration.

The duration of antiresorptive therapy is an important risk factor for medication-related osteonecrosis of the jaw. We performed a pilot study using quantitative analysis by bone scintigraphy to test the hypothesis that mandibular metabolism is affected by long-term bisphosphonate (BP) therapy. Our primary objectives were to assess changes in bone metabolism of the mandible in response to long-term BP therapy and compare the bone metabolism changes of the mandible with other bone sites. We compared the metabolic difference at the site in the mandible unaffected by disease, the humerus and the femur between 14 osteoporosis patients who were being treated with BP (BP group) and 14 patients who were not being treated with BP (control group) using a quantitative analysis and bone scintigraphy. Study endpoints were the mean and maximum bone uptake values (BUVs) quantified using bone scintigraphy images of the mandible, humerus and femur. Quantified images of the site in the mandible unaffected by disease had significantly higher mean and maximum BUVs compared to the controls (mean, 0.74 vs. 0.49, p = 0.019; max., 1.29 vs. 0.85, p = 0.009, respectively). The mean and maximum BUV of femur ROIs in the BP group were significantly lower than those in control patients (mean BUV, 0.23 vs. 0.30, p = 0.039; max. BUV, 0.43 vs. 0.53, p = 0.024, respectively). This is the first report of mandible changes in response to long-term BP treatment, using bone scintigraphy. The results using bone scintigraphy demonstrated that the bone metabolism of the intact mandible is affected by a long-term administration of BP.

Cleansing effect of acidic L-arginine on human oral biofilm.

BACKGROUND: Dental plaque formed on tooth surfaces is a complex ecosystem composed of diverse oral bacteria and salivary components. Accumulation of dental plaque is a risk factor for dental caries and periodontal diseases. L-arginine has been reported to decrease the risk for dental caries by elevating plaque pH through the activity of arginine deiminase in oral bacteria. Here we evaluated the potential of L-arginine to remove established oral biofilms. METHODS: Biofilms were formed using human saliva mixed with Brain Heart Infusion broth supplemented with 1 % sucrose in multi-well plates or on plastic discs. After washing the biofilms with saline, citrate (10 mM, pH3.5), or L-arginine (0.5 M, pH3.5), the retained biofilms were analyzed by crystal violet staining, scanning electron microscopy, and Illumina-based 16S rDNA sequencing. RESULTS: Washing with acidic L-arginine detached oral biofilms more efficiently than saline and significantly reduced biofilm mass retained in multi-well plates or on plastic discs. Illumina-based microbiota analysis showed that citrate (pH3.5) preferentially washed out Streptococcus from mature oral biofilm, whereas acidic L-arginine prepared with 10 mM citrate buffer (pH3.5) non-specifically removed microbial components of the oral biofilm. CONCLUSIONS: Acidic L-arginine prepared with citrate buffer (pH3.5) effectively destabilized and removed mature oral biofilms. The acidic L-arginine solution described here could be used as an additive that enhances the efficacy of mouth rinses used in oral hygiene.

Potent inhibitory effects of D-tagatose on the acid production and water-insoluble glucan synthesis of Streptococcus mutans GS5 in the presence of sucrose.

We examined and compared the inhibitory effects of D-tagatose on the growth, acid production, and water-insoluble glucan synthesis of GS5, a bacterial strain of Streptococcus mutans, with those of xylitol, D-psicose, L-psicose and L-tagatose. GS5 was cultured for 12h in a medium containing 10% (w/v) of xylitol, D-psicose, L-psicose, D-tagatose or L-tagatose, and the inhibitory effect of GS5 growth was assessed. Each sugar showed different inhibitory effects on GS5. Both D-tagatose and xylitol significantly inhibited the acid production and water-insoluble glucan synthesis of GS5 in the presence of 1% (w/v) sucrose. However, the inhibitory effect of acid production by D-tagatose was significantly stronger than that of xylitol in presence of sucrose.

Risk factors for post-extraction infection of mandibular third molar: A retrospective clinical study.

Post-extraction infection is one of the most concerning complications of mandibular third molar extraction, which is the most common procedure in oral and maxillofacial surgery. We investigated risk factors for post-extraction infection by retrospectively analyzing 2,513 teeth/cases of mandibular third molar extraction (1,040 males, 1,473 females) performed at a single medical facility in Kobe, Japan from January 2014 to May 2022. The predictive variables were categorized as patient attributes, health status, and anatomic, pathological, and operative variables that may be associated with post-extraction infection. The outcome variable was the post-extraction infection rate. The post-extraction infection rate was 5.73 % (144 of the 2,513 teeth), and the mean age of the patients with a post-extraction infection was 41.76 ± 16.8 years. Our analyses also revealed that the postoperative infection rate was significantly increased in patients aged ≥36 years. A multivariate logistic regression analysis showed that the following variables were significantly associated with post-extraction infection: preoperative antibiotic administration (odds ratio [OR] 4.68, p < 0.001), postoperative paresthesia of the inferior alveolar nerve (OR 4.34, p < 0.001), intraoperative hemostatic procedure (OR 1. 74, p = 0.008), position of Pell and Gregory classifications (OR 1. 70, p < 0.001), Winter's classification (OR 1.28, p < 0.03), and age (OR 1.03, p < 0.001). Oral and maxillofacial surgeons should be aware of these risk factors.

Risk factors for postoperative infection after bilateral sagittal split ramus osteotomy: A retrospective analysis.

BACKGROUND: This retrospective clinical study investigated risk factors for infection following bilateral sagittal split ramus osteotomy (BSSO) as orthognathic surgery, including the patients' general condition, local factors, and surgical factors. PATIENTS AND METHODS: The cases of 160 mandibular sites of 80 Japanese patients (26 males, 54 females; mean ± SD age: 25.3 ± 7.7 years, range 16-55 yrs) with a jaw deformity who underwent BSSO orthognathic surgery at our Department of Oral and Maxillofacial Surgery between Jan. 2017 and Dec. 2022 were analyzed. Potential risk factors were classified as clinical predictive variables. Descriptive and univariate statistics were computed. A multivariate analysis was performed with logistic regression. RESULTS: Fifteen mandibular sites (9.4 %) were complicated with postoperative infection. The multivariate analysis revealed significant differences in facial asymmetry (OR 24.0, p = 0.0002) and the amount of mandibular movement (OR 0.664, p = 0.011) between the sites with and without infection. CONCLUSIONS: Among clinical variables, facial asymmetry was the strongest risk factor for post-BSSO infection, followed by the amount of mandibular movement.

Risk Factors for Delayed-Onset Infection after Mandibular Wisdom Tooth Extractions.

Wisdom tooth extraction is one of the most commonly performed procedures by oral maxillofacial surgeons. Delayed-onset infection (DOI) is a rare complication of wisdom tooth extraction, and it occurs ~1-4 weeks after the extraction. In the present study, risk factors for DOI were investigated by retrospectively analyzing the cases of 1400 mandibular wisdom tooth extractions performed at Kagawa University Hospital from April 2015 to June 2022. Inclusion criteria were patients aged >15 years with a wisdom tooth extraction per our procedure. The exclusion criteria were patients with insufficient medical records, a >30-mm lesion around the wisdom tooth shown via X-ray, colonectomy, radiotherapy treatment of the mandible, the lack of panoramic images, and lesions other than a follicular cyst. The DOI incidence was 1.1% (16 cases), and univariate analyses revealed that the development of DOI was significantly associated with the Winter classification (p = 0.003), position (p = 0.003), hypertension (p = 0.011), and hemostatic agent use (p = 0.004). A multivariate logistic regression analysis demonstrated that position (OR = B for A, 7.75; p = 0.0163), hypertension (OR = 7.60, p = 0.013), and hemostatic agent use (OR = 6.87, p = 0.0022) were significantly associated with DOI development. Hypertension, hemostatic use, and position were found to be key factors for DOI; long-term observation may thus be necessary for patients with these risk factors.

Effectiveness of deep learning classifiers in histopathological diagnosis of oral squamous cell carcinoma by pathologists.

The study aims to identify histological classifiers from histopathological images of oral squamous cell carcinoma using convolutional neural network (CNN) deep learning models and shows how the results can improve diagnosis. Histopathological samples of oral squamous cell carcinoma were prepared by oral pathologists. Images were divided into tiles on a virtual slide, and labels (squamous cell carcinoma, normal, and others) were applied. VGG16 and ResNet50 with the optimizers stochastic gradient descent with momentum and spectral angle mapper (SAM) were used, with and without a learning rate scheduler. The conditions for achieving good CNN performances were identified by examining performance metrics. We used ROCAUC to statistically evaluate diagnostic performance improvement of six oral pathologists using the results from the selected CNN model for assisted diagnosis. VGG16 with SAM showed the best performance, with accuracy = 0.8622 and AUC = 0.9602. The diagnostic performances of the oral pathologists statistically significantly improved when the diagnostic results of the deep learning model were used as supplementary diagnoses (p-value = 0.031). By considering the learning results of deep learning model classifiers, the diagnostic accuracy of pathologists can be improved. This study contributes to the application of highly reliable deep learning models for oral pathological diagnosis.

The effect of zoledronic acid and denosumab on the mandible and other bones: a 18F-NaF-PET study.

OBJECTIVES: The primary purpose of this study was to determine whether both zoledronic acid (ZA) and denosumab (Dmab) equally suppress bone remodeling of the normal mandible, and the secondary purpose was to determine the influence of ZA and Dmab on other normal bones. METHODS: 18F-sodium fluoride-positron-emission-tomography (18F-NaF-PET) was used to perform quantitative analysis of the bone metabolism in various parts. The end points of the study were the mean standardized uptake value (SUV) of each member of the ZA group (n = 9), the Dmab group (n = 16), and the Control group (n = 23). RESULTS: The SUV at the thoracic vertebrae in the ZA group were significantly lower than those of the Dmab and Control group (p < 0.05) In addition, the mean SUVs of the cervical vertebrae in the ZA group were significantly lower than those in the Control group (p < 0.05). There was no significant difference among ZA, Dmab and Control group in the other sites. There was no significant difference between the Dmab and Control groups at all sites. CONCLUSIONS: The remodeling of mandible was not suppressed due to the treatment with anti-resorptive agents. Differences in the mechanisms of action between the BP and Dmab caused the specificity of the effect on the metabolism of normal bone.

Galectin-9 expands immunosuppressive macrophages to ameliorate T-cell-mediated lung inflammation.

Galectin-9 (Gal-9) plays pivotal roles in the modulation of innate and adaptive immunity to suppress T-cell-mediated autoimmune models. However, it remains unclear if Gal-9 plays a suppressive role for T-cell function in non-autoimmune disease models. We assessed the effects of Gal-9 on experimental hypersensitivity pneumonitis induced by Trichosporon asahii. When Gal-9 was given subcutaneously to C57BL/6 mice at the time of challenge with T. asahii, it significantly suppressed T. asahii-induced lung inflammation, as the levels of IL-1, IL-6, IFN-gamma, and IL-17 were significantly reduced in the BALF of Gal-9-treated mice. Moreover, co-culture of anti-CD3-stimulated CD4 T cells with BALF cells harvested from Gal-9-treated mice on day 1 resulted in diminished CD4 T-cell proliferation and decreased levels of IFN-gamma and IL-17. CD11b(+)Ly-6C(high)F4/80(+) BALF Mphi expanded by Gal-9 were responsible for the suppression. We further found in vitro that Gal-9, only in the presence of T. asahii, expands CD11b(+)Ly-6C(high)F4/80(+) cells from BM cells, and the cells suppress T-cell proliferation and IFN-gamma and IL-17 production. The present results indicate that Gal-9 expands immunosuppressive CD11b(+)Ly-6C(high) Mphi to ameliorate Th1/Th17 cell-mediated hypersensitivity pneumonitis.