Innate phase production of IFN-γ by memory and effector T cells expressing early activation marker CD69 during infection with Cryptococcus deneoformans in the lungs

Cryptococcus deneoformans is a yeast-type fungus that causes fatal meningoencephalitis in immunocompromised patients and evades phagocytic cell elimination through an escape mechanism. Memory T (Tm) cells play a central role in preventing the reactivation of this fungal pathogen. Among these cells, tissue-resident memory T (TRM) cells quickly respond to locally invaded pathogens. This study analyzes the kinetics of effector T (Teff) cells and Tm cells in the lungs after cryptococcal infection. Emphasis is placed on the kinetics and cytokine expression of TRM cells in the early phase of infection. CD4+ Tm cells exhibited a rapid increase by day 3, peaked at day 7, and then either maintained their levels or exhibited a slight decrease until day 56. In contrast, CD8+ Tm cells reached their peak on day 3 and thereafter decreased up to day 56 post-infection. These Tm cells were predominantly composed of CD69+ TRM cells and CD69+ CD103+ TRM cells. Disruption of the CARD9 gene resulted in reduced accumulation of these TRM cells and diminished interferon (IFN) -γ expression in TRM cells. TRM cells were derived from T cells with T cell receptors non-specific to ovalbumin in OT-II mice during cryptococcal infection. In addition, TRM cells exhibited varied behavior in different tissues. These results underscore the importance of T cells, which produce IFN-γ in the lungs during the early stage of infection, in providing early protection against cryptococcal infection through CARD9 signaling.

Epidemiologic, clinical, and genetic characteristics of influenza C virus infections among outpatients and inpatients in Sendai, Japan from 2006 to 2020

BACKGROUND

Influenza C virus is a pathogen that causes acute respiratory illness in children. The clinical information about this virus is limited because of the small number of isolated viruses compared to influenza A or B viruses.

METHODS

A total of 60 influenza C viruses were isolated by clinical tests using cell culture methods conducted in one hospital and one clinic during the 15 years from 2006 to 2020. These 60 cases were retrospectively analyzed by comparing outpatients and inpatients. Moreover, isolated viruses were analyzed for genomic changes during the study period.

RESULTS

All were younger than 7 years, and 73% of inpatients (19 out of 26) were under 2 years of age. A significant difference was found in the frequency of pneumonia, accounting for 45% and 4% of inpatients and outpatients, respectively. Most of the viruses isolated from 2006 to 2012 belonged to the S/A sublineage of the C/Sao Paulo lineage, but three sublineage viruses, including the S/A sublineage with K190N mutation, S/V sublineage, and C/Kanagawa lineage, have cocirculated since 2014. Moreover, S/A sublineage viruses were undergoing reassortment since 2014, suggesting significant changes in the virus, both antigenically and genetically. Of the 10 strains from patients with pneumonia, 7 were in the S/A sublineage, which had circulated from 2006 to 2012.

CONCLUSION

Infants under 2 years of age were more likely to be hospitalized with pneumonia. The genomic changes that occurred in 2014 were suggested to affect the ability of the virus to spread.

Variation in Thermal Stability among Respiratory Syncytial Virus Clinical Isolates under Non-Freezing Conditions

Virus isolates are not only useful for diagnosing infections, e.g., respiratory syncytial virus (RSV), but can also facilitate many aspects of practical viral studies such as analyses of antigenicity and the action mechanisms of antivirals, among others. We have been isolating RSV from clinical specimens from patients with respiratory symptoms every year since our first isolation of RSV in 1964, and isolation rates have varied considerably over the years. As collected clinical specimens are conventionally stored in a refrigerator from collection to inoculation into cells, we hypothesized that certain storage conditions or associated factors might account for these differences. Hence, we evaluated the thermal stability of a total of 64 viruses isolated from 1998 to 2018 upon storage at 4 °C and 20 °C for a defined duration. Interestingly, and contrary to our current understanding, 22 strains (34%) showed a greater loss of viability upon short-term storage at 4 °C than at 20 °C. Thirty-seven strains (57%) showed an almost equal loss, and only five strains (8%) were more stable at 4 °C than at 20 °C. This finding warrants reconsideration of the temperature for the temporary storage of clinical samples for RSV isolation.

Deficiency of lung-specific claudin-18 leads to aggravated infection with Cryptococcus deneoformans through dysregulation of the microenvironment in lungs

Cryptococcus deneoformans is an opportunistic fungal pathogen that infects the lungs via airborne transmission and frequently causes fatal meningoencephalitis. Claudins (Cldns), a family of proteins with 27 members found in mammals, form the tight junctions within epithelial cell sheets. Cldn-4 and 18 are highly expressed in airway tissues, yet the roles of these claudins in respiratory infections have not been clarified. In the present study, we analyzed the roles of Cldn-4 and lung-specific Cldn-18 (luCldn-18) in host defense against C. deneoformans infection. luCldn-18-deficient mice exhibited increased susceptibility to pulmonary infection, while Cldn-4-deficient mice had normal fungal clearance. In luCldn-18-deficient mice, production of cytokines including IFN-γ was significantly decreased compared to wild-type mice, although infiltration of inflammatory cells including CD4⁺ T cells into the alveolar space was significantly increased. In addition, luCldn-18 deficiency led to high K⁺ ion concentrations in bronchoalveolar lavage fluids and also to alveolus acidification. The fungal replication was significantly enhanced both in acidic culture conditions and in the alveolar spaces of luCldn-18-deficient mice, compared with physiological pH conditions and those of wild-type mice, respectively. These results suggest that luCldn-18 may affect the clinical course of cryptococcal infection indirectly through dysregulation of the alveolar space microenvironment.

Production of IL-17A at Innate Immune Phase Leads to Decreased Th1 Immune Response and Attenuated Host Defense against Infection with Cryptococcus deneoformans

IL-17A is a proinflammatory cytokine produced by many types of innate immune cells and Th17 cells and is involved in the elimination of extracellularly growing microorganisms, yet the role of this cytokine in the host defense against intracellularly growing microorganisms is not well known. Cryptococcus deneoformans is an opportunistic intracellular growth fungal pathogen that frequently causes fatal meningoencephalitis in patients with impaired immune responses. In the current study, we analyzed the role of IL-17A in the host defense against C. deneoformans infection. IL-17A was quickly produced by γδT cells at an innate immune phase in infected lungs. In IL-17A gene-disrupted mice, clearance of this fungal pathogen and the host immune response mediated by Th1 cells were significantly accelerated in infected lungs compared with wild-type mice. Similarly, killing of this fungus and production of inducible NO synthase and TNF-α were significantly enhanced in IL-17A gene-disrupted mice. In addition, elimination of this fungal pathogen, Th1 response, and expression of IL-12Rβ2 and IFN-γ in NK and NKT cells were significantly suppressed by treatment with rIL-17A. The production of IL-12p40 and TNF-α from bone marrow-derived dendritic cells stimulated with C. deneoformans was significantly suppressed by rIL-17A. In addition, rIL-17A attenuated Th1 cell differentiation in splenocytes from transgenic mice highly expressing TCR for mannoprotein 98, a cryptococcal Ag, upon stimulation with recombinant mannoprotein 98. These data suggest that IL-17A may be involved in the negative regulation of the local host defense against C. deneoformans infection through suppression of the Th1 response.

Distinct Roles for Dectin-1 and Dectin-2 in Skin Wound Healing and Neutrophilic Inflammatory Responses

C-type lectin receptors recognize microbial polysaccharides. The C-type lectin receptors such as dendritic cell-associated C-type lectin (Dectin)-1 and Dectin-2, which are triggered by β-glucan and α-mannan, respectively, contribute to upregulation of the inflammatory response. Recently, we demonstrated that activation of the Dectin-2 signal delayed wound healing; in previous studies, triggering the Dectin-1 signal promoted this response. However, the precise roles of these C-type lectin receptors in skin wound healing remain unclear. This study was conducted to determine the roles of Dectin-1 and Dectin-2 in skin wound healing, with a particular focus on the kinetics of neutrophilic inflammatory response. Full-thickness wounds were created on the backs of C57BL/6 mice, and the effects of Dectin-1 or Dectin-2 deficiency and those of β-glucan or α-mannan administration were examined. We also analyzed wound closure, histological findings, and neutrophilic inflammatory response, including neutrophil extracellular trap formation at the wound sites. We found that Dectin-1 contributed to the acceleration of wound healing by inducing early-phase neutrophil accumulation, whereas Dectin-2 was involved in prolonged neutrophilic responses and neutrophil extracellular trap formation, leading to delayed wound healing. Dectin-2 deficiency also improved collagen deposition and TGF-β1 expression. These results suggest that Dectin-1 and Dectin-2 have different roles in wound healing through their different effects on the neutrophilic response.

Dectin-2-mediated signaling triggered by the cell wall polysaccharides of Cryptococcus neoformans

Cryptococcus neoformans is rich in polysaccharides of the cell wall and capsule. Dectin-2 recognizes high-mannose polysaccharides and plays a central role in the immune response to fungal pathogens. Previously, we demonstrated Dectin-2 was involved in the activation of dendritic cells upon stimulation with C. neoformans, suggesting the existence of a ligand recognized by Dectin-2. In the present study, we examined the cell wall structures of C. neoformans contributing to the Dectin-2-mediated activation of immune cells. In a NFAT-GFP reporter assay of the reported cells expressing Dectin-2, the lysates, but not the whole yeast cells, of an acapsular strain of C. neoformans (Cap67) delivered Dectin-2-mediated signaling. This activity was detected in the supernatant of β-glucanase-treated Cap67 and more strongly in the semi-purified polysaccharides of this supernatant using ConA-affinity chromatography (ConA-bound fraction), in which a large amount of saccharides, but not protein, were detected. Treatment of this supernatant with periodic acid and the addition of excessive mannose, but not glucose or galactose, strongly inhibited this activity. The ConA-bound fraction of the β-glucanase-treated Cap67 supernatant was bound to Dectin-2-Fc fusion protein in a dose-dependent manner and strongly induced the production of interleukin-12p40 and tumour necrosis factor-α by dendritic cells; this was abrogated under the Dectin-2-deficient condition. Finally, 98 kDa mannoprotein (MP98) derived from C. neoformans showed activation of the reporter cells expressing Dectin-2. These results suggested that a ligand with mannose moieties may exist in the cell walls and play a critical role in the activation of dendritic cells during infection with C. neoformans.

Defect of Interferon γ Leads to Impaired Wound Healing through Prolonged Neutrophilic Inflammatory Response and Enhanced MMP-2 Activation

Interferon (IFN)-γ is mainly secreted by CD4+ T helper 1 (Th1), natural killer (NK) and NKT cells after skin injury. Although IFN-γ is well known regarding its inhibitory effects on collagen synthesis by fibroblasts in vitro, information is limited regarding its role in wound healing in vivo. In the present study, we analyzed how the defect of IFN-γ affects wound healing. Full-thickness wounds were created on the backs of wild type (WT) C57BL/6 and IFN-γ-deficient (KO) mice. We analyzed the percent wound closure, wound breaking strength, accumulation of leukocytes, and expression levels of COL1A1, COL3A1, and matrix metalloproteinases (MMPs). IFN-γKO mice exhibited significant attenuation in wound closure on Day 10 and wound breaking strength on Day 14 after wound creation, characteristics that are associated with prolonged neutrophil accumulation. Expression levels of COL1A1 and COL3A1 mRNA were lower in IFN-γKO than in WT mice, whereas expression levels of MMP-2 (gelatinase) mRNA were significantly greater in IFN-γKO than in WT mice. Moreover, under neutropenic conditions created with anti-Gr-1 monoclonal antibodies, wound closure in IFN-γKO mice was recovered through low MMP-2 expression levels. These results suggest that IFN-γ may be involved in the proliferation and maturation stages of wound healing through the regulation of neutrophilic inflammatory responses.

Dectin-2-Mediated Signaling Leads to Delayed Skin Wound Healing through Enhanced Neutrophilic Inflammatory Response and Neutrophil Extracellular Trap Formation

Dendritic cell-associated C-type lectin-2 (i.e., dectin-2) recognizes fungal polysaccharides, including α-mannan. Dectin-2-mediated recognition of fungi, such as Candida albicans, leads to NF-κB activation, which induces production of inflammatory cytokines. However, the role of dectin-2 in skin wound healing remains unclear. In this study, we sought to determine how dectin-2 deficiency and the administration of α-mannan affected the wound healing process. Full-thickness wounds were created on the backs of wild type C57BL/6 and dectin-2-deficient mice. We analyzed wound closure, histological findings, and re-epithelialization. We also examined the neutrophilic inflammatory responses and neutrophil extracellular trap (NET)-osis at the wound sites after administration of α-mannan. The percent wound closure and re-epithelialization was significantly accelerated in dectin-2-knockout mice compared with wild-type mice on days 3 and 5 after wounding. In contrast, administration of α-mannan delayed wound closure in wild-type mice, and these responses were canceled in dectin-2-knockout mice. Furthermore, mice administered α-mannan, neutrophil infiltration was prolonged, and the expression of citrullinated histone, an indicator of NETosis, at the wound sites was accelerated. Administration of a neutrophil elastase inhibitor significantly improved the delayed wound healing caused by α-mannan. These results suggest that dectin-2 may have a deep impact on the skin wound healing process through regulation of neutrophilic responses.

FTY720 stimulated ROS generation and the Sty1/Atf1 signaling pathway in the fission yeast Schizosaccharomyces pombe

Fingolimod hydrochloride (FTY720) is the first-in-class immune modulator known as sphingosine 1-phosphate (S1P) receptor agonists. FTY720 has also been reported to exert a variety of physiological functions such as antitumor effect, angiogenesis inhibition, and Ca2+ mobilization. Here, we show that FTY720 treatment induced reactive oxygen species (ROS) accumulation, and investigated the effect of FTY720 on the stress-activated MAP kinase Spc1/Sty1, a functional homologue of p38 MAPK, using a Renilla luciferase reporter construct fused to the CRE, which gives an accurate measure of the transcriptional activity of Atf1 and thus serves as a faithful readout of the Spc1/Sty1 MAPK signaling in response to oxidative stresses. FTY720 stimulated the CRE responses in a concentration-dependent manner, which was markedly reduced by deletion of the components of the Spc1/Sty1 MAPK pathway. The blockade of ROS production by NAC (N-acetyl-L-cysteine) significantly reversed the FTY720-induced ROS accumulation, subsequent activation of the Spc1/Sty1 MAPK pathway, and inhibition of cell proliferation. Cells lacking the components of the Spc1/Sty1 MAPK exhibited higher sensitivity to FTY720 and higher ROS levels upon FTY720 treatment than in wild-type cells. Thus, our results demonstrate the usefulness of fission yeast for elucidating the FTY720-mediated signaling pathways involving ROS.

Fingolimod (FTY720) stimulates Ca(2+)/calcineurin signaling in fission yeast

Fingolimod hydrochloride (FTY720) is the first in class of sphingosine 1-phosphate (S1P) receptor modulator approved to treat multiple sclerosis via down-regulation of G protein-coupled S1P receptor 1 by its phosphorylated form (FTY720-P). Many studies have revealed that FTY720 exerts various biological effects, including antitumor activities, angiogenesis inhibition, Ca(2+) mobilization and apoptosis, independently of S1P receptors. However, the exact mechanisms underlying their effects or signaling pathways mediated by FTY720 have not been completely established. To gain further insights into molecular mechanisms of FTY720 action, the effect of FTY720 on Ca(2+) signaling in fission yeast was analyzed. The addition of Ca(2+) enhanced the sensitivity induced by FTY720, and mutants lacking genes required for calcium homeostasis, including calcineurin and its downstream transcription factor, Ppb1-responsive zinc finger protein (Prz1), were hypersensitive to FTY720 and CaCl2. The effect of FTY720 on calcineurin signaling was monitored by utilizing a luciferase reporter construct fused to three tandem repeats of the calcineurin-dependent response element (CDRE), which gives an accurate measure of calcineurin activity. The addition of FTY720 increased calcineurin activity as well as Ca(2+) influx in a concentration-dependent manner. Notably, the FTY720-mediated Ca(2+) influx and calcineurin activation were reduced markedly by the deletion of yam8 (+) or cch1 (+) encoding putative subunits of a Ca(2+) channel. Consistently, the deletion of Pmk1 mitogen-activated protein kinase (MAPK), which plays an important role in the activation of the Yam8/Cch1 channel, markedly decreased the intracellular Ca(2+) levels upon FTY720 treatment. These results suggest that the FTY720-stimulated Ca(2+)/calcineurin signaling activation partly involves the Yam8/Cch1 channel in fission yeast.

Chemotherapeutic treatment of priapism in metastatic rectal cancer

A 65-year-old man was admitted with penile tenderness and dysuria due to priapism. Enhanced computed tomography revealed metastatic tumors in the liver, lung, sacrum and lymph nodes. Advanced rectal cancer, detected by colonoscopy as a primary tumor, was treated with chemotherapy (FOLFOX4). Although the rectal cancer showed no change, five months of chemotherapy improveid the priapism, suggesting that chemotherapy can improve rare symptoms of rectal cancer.

Ascitic fluid to serum bilirubin concentration ratio for the classification of transudates or exudates

OBJECTIVE

We compared the ascitic fluid to serum bilirubin ratio with three other ways of classifying ascitic fluid to the categories of exudate or transudate: the serum-ascites albumin gradient, the total protein concentration of the fluid, and the adaptation of Light's criteria for the detection of pleural fluid exudate, i.e., fluid to serum protein or LDH ratio or fluid LDH concentration. (Recently it has been reported that the pleural fluid to serum bilirubin ratio is statistically equivalent to Light's criteria.) Also, we evaluated whether the addition of the bilirubin ratio to the other criteria increases their diagnostic accuracy.

METHODS

Eighty-one specimens of ascitic fluid from 81 different patients were obtained. They were analyzed prospectively by SMA12, whereas the category of the fluid was determined according to the clinical diagnosis. The diagnostic accuracy of each criterion alone and in combination with the bilirubin ratio, with reference to the contended etiology, were evaluated.

RESULTS

The best criterion is the albumin gradient (overall accuracy = 0.84). The bilirubin and LDH ratio criteria had equivalent overall accuracy (0.815 and 0.802, respectively). The addition of the bilirubin ratio to any criterion did not improve its predictive or overall accuracy.

CONCLUSIONS

Ascitic fluid to serum bilirubin ratio is an additional marker for the distinction of transudate from exudate. A ratio > 0.6 has a statistically significant association with exudate.

Fibrosing alveolitis associated with primary antiphospholipid syndrome

The spectrum of the primary antiphospholipid syndrome has expanded in recent years. It has been associated with a number of non-thrombotic syndromes such as pulmonary hypertension, adrenal insufficiency, chorea and avascular necrosis of bone. Yet, it has not been described in association with inflammatory pulmonary disease. We describe a young male with definite primary antiphospholipid syndrome who developed insidious diffuse pulmonary infiltrates. The histopathologic examination of the involved lung demonstrated alveolitis and fibrosis. We suggest that this pulmonary involvement may represent another manifestation of the primary antiphospholipid syndrome.

Multimodal treatment of hepatocellular carcinoma

Our multimodal treatment of hepatocellular carcinoma (HCC) has brought about a significant improvement of the survival rate. It consists of a combination of hepatectomy and transcatheter arterial embolization using lipiodol (L-TAE). In order to facilitate L-TAE, we have developed a special catheter with notches. A group of patients with HCC (124 cases), excluding cases with absolutely non-curative resections and operative deaths, were treated between December 1980 and November 1986. Each case was treated for more than 1 year after hepatectomy. The patients were divided into two groups: A, patients with a single tumor not larger than 5 cm, and B, cases with larger tumors or more than one lesion. Some patients in each group were treated with L-TAE after hepatectomy. In group A, there was no significant difference in survival between treated and non-treated cases. In group B, L-TAE gave a significantly better survival than no postoperative treatment.