Infections due to carbapenem-resistant Klebsiella pneumoniae have emerged as a global threat due to its wide-spread antimicrobial resistance. Transplant recipients and patients with hematologic malignancies have high mortality rate suggesting host factors in susceptibility. We developed a model of pulmonary infection using ST258 C4, KPC-2 clone, which are predominant Klebsiella pneumoniae carbapenemase (KPC)-producing bacteria, and demonstrated that Rag2-/-Il2rg-/- mice, but not wildtype C57BL/6 or Rag2-/- mice, were susceptible to this opportunistic infection. Using single-cell RNA-seq in infected Rag2-/- mice, we identified distinct clusters of Ifng+ NK cells and Il17a+, Il22+, and inducible T-cell costimulatory molecule (ICOS)+ group 3 innate lymphoid cells (ILCs) that were critical for host resistance. As solid organ transplantation is a risk factor, we generated a more clinically relevant model using FK506 in wildtype C57BL/6 mice. We further demonstrated that immunotherapy with recombinant IL-22 treatment ameliorated the ST258 pulmonary infection in both FK506 treated WT mice and Rag2-/-Il2rg-/- mice via hepatic IL-22ra1 signaling. These data support the development of host directed immunotherapy as an adjunct treatment to new antibiotics.
Naoki Iwanaga, Ivy Sandquist, Alanna Wanek, Janet E. McCombs, Kejing Song, Jay Kolls
Acinetobacter baumannii is an extremely versatile multidrug resistant pathogen with a very high mortality rate therefore, it has become crucial to understand the host response during its infection. Given the importance of mice for modelling infection and their role in pre-clinical drug development equal emphasis should be placed on the utilization of both sexes. Through our studies using a murine model of acute pneumonia with A. baumannii, we observed that female mice were more susceptible to infection. Likewise, treatment of male mice with estradiol increased their susceptibility to infection. Analysis of the airway compartment revealed enhanced inflammation and reduced neutrophil and alveolar macrophage numbers compared to male mice. Depletion of either neutrophils or alveolar macrophages was important for bacterial clearance however, depletion of alveolar macrophages further exacerbated female susceptibility due to severe alterations in metabolic homoeostasis. Our data highlights the importance of utilizing both sexes when assessing host immune pathways.
Silvia Pires, Adeline C. Peignier, Jeremy Seto, Davida S. Smyth, Dane Parker
Diabetes is a significant risk factor for the development of active tuberculosis. In this study, we used a mouse model of type 2 diabetes mellitus (T2DM) to determine the effect of prior Bacillus Calmette-Guérin (BCG) vaccination on immune responses to Mycobacterium tuberculosis (Mtb) infection. We found that, at 6–7 months after Mtb infection, 90% of the Mtb-infected T2DM mice died, whereas only 50% of BCG-vaccinated T2DM-Mtb–infected mice died. Moreover, 40% of the PBS-treated uninfected T2DM mice and 30% of the uninfected BCG-vaccinated T2DM mice died, whereas all uninfected and infected nondiabetic mice survived. BCG vaccination was less effective in reducing the lung bacterial burden of Mtb-infected T2DM mice compared with Mtb-infected nondiabetic mice. BCG vaccination significantly reduced lung inflammation in Mtb-infected T2DM mice compared with that of unvaccinated T2DM mice infected with Mtb. Furthermore, reduced mortality of BCG-vaccinated Mtb-infected T2DM mice is associated with expansion of IL-13–producing CXCR3+ Tregs in the lungs of Mtb-infected T2DM mice. Recombinant IL-13 and Tregs from BCG-vaccinated Mtb-infected T2DM mice converted proinflammatory M1 macrophages to antiinflammatory M2 macrophages. Our findings suggest a potentially novel role for BCG in preventing excess inflammation and mortality in T2DM mice infected with Mtb.
Rajesh Kumar Radhakrishnan, Ramya Sivangala Thandi, Deepak Tripathi, Padmaja Paidipally, Madeline Kay McAllister, Sachin Mulik, Buka Samten, Ramakrishna Vankayalapati
Herpes simplex virus-2 (HSV-2) and HSV-1 both can cause genital herpes, a chronic infection that establishes a latent reservoir in the nervous system. Clinically, the recurrence frequency of HSV-1 genital herpes is considerably less than HSV-2 genital herpes, which correlates with reduced neuronal infection. The factors dictating the disparate outcomes of HSV-1 and HSV-2 genital herpes are unclear. In this study, we show that vaginal infection of mice with HSV-1 leads to the rapid appearance of mature DCs in the draining lymph node, which is dependent on an early burst of NK cell–mediated IFN-γ production in the vagina that occurs after HSV-1 infection but not HSV-2 infection. Rapid DC maturation after HSV-1 infection, but not HSV-2 infection, correlates with the accelerated generation of a neuroprotective T cell response and early accumulation of IFN-γ–producing T cells at the site of infection. Depletion of T cells or loss of IFN-γ receptor (IFN-γR) expression in sensory neurons both lead to a marked loss of neuroprotection only during HSV-1, recapitulating a prominent feature of HSV-2 infection. Our experiments reveal key differences in host control of neuronal HSV-1 and HSV-2 infection after genital exposure of mice, and they define parameters of a successful immune response against genital herpes.
Aisha G. Lee, Jason M. Scott, Maria Rita Fabbrizi, Xiaoping Jiang, Dorothy K. Sojka, Mark J. Miller, Megan T. Baldridge, Wayne M. Yokoyama, Haina Shin
Chikungunya virus (CHIKV) infection causes acute febrile illness in humans and some of these individuals develop a debilitating chronic arthritis that can persist for months to years for reasons that remain poorly understood. In this study from India, we characterized antibody response patterns in chikungunya febrile patients and further assessed the association of these initial febrile phase antibody response patterns with protection versus progression to developing chronic arthritis. We found five distinct patterns of the antibody responses in febrile phase: No CHIKV binding or Neutralizing (NT) antibodies but PCR positive, IgM alone with no NT activity, IgM alone with NT activity, IgM and IgG without NT activity, IgM and IgG with NT activity. A 20-month follow-up showed that appearance of NT activity regardless of antibody isotype or appearance of IgG regardless of NT activity during the initial febrile phase is associated with a robust protection against developing chronic arthritis in the future. These findings, while providing novel insights on correlates of protective immunity against chikungunya-induced chronic arthritis, suggest that qualitative differences in the antibody response patterns that have evolved during the febrile phase can serve as biomarkers, that allow prediction of protection or progression to chronic arthritis in the future.
Kaustuv Nayak, Vineet Jain, Manpreet Kaur, Naushad Khan, Kamalvishnu Gottimukkala, Charu Aggarwal, Rohit Sagar, Shipra Gupta, Ramesh Chandra Rai, Kritika Dixit, Mohammad Islamuddin, Anil Verma, Deepti Maheshwari, Yadya M. Chawla, Elluri Seetharami Reddy, Harekrushna Panda, Pragati Sharma, Priya Bhatnagar, Prabhat Singh, Siva Raghavendhar, Ashok Kumar Patel, Vinod H. Ratageri, Anmol Chandele, Pratima Ray, Kaja Murali-Krishna
Dengue (DENV) and Zika viruses (ZIKV) are closely related mosquito-borne flaviviruses that co-circulate in tropical regions and constitute major threats to global human health. Whether preexisting immunity to one virus affects disease caused by the other during primary or secondary infections is unknown but is critical in preparing for future outbreaks and predicting vaccine safety. Using a human skin explant model, we show that DENV-3 immune sera increased recruitment and infection of Langerhans cells, macrophages and dermal dendritic cells following inoculation with DENV-2 or ZIKV. Similarly, ZIKV immune sera enhanced infection with DENV-2. Immune sera increased migration of infected Langerhans cells to dermis and emigration of infected cells out of skin. Heterotypic immune sera increased viral RNA in dermis almost tenfold and reduced the amount of virus required to infect a majority of myeloid cells by 100 to 1,000 fold. Enhancement was associated with cross-reactive IgG and induction of IL-10 expression and was mediated by both CD32 and CD64 Fcγ receptors. These findings reveal that preexisting heterotypic immunity greatly enhances DENV and ZIKV infection, replication and spread in human skin. This relevant tissue model will be valuable in assessing the efficacy and risk of dengue and Zika vaccines in humans.
Priscila M.S. Castanha, Geza Erdos, Simon C. Watkins, Louis D. Falo, Jr., Ernesto T.A. Marques, Simon M. Barratt-Boyes
To investigate the nationwide severe fever with thrombocytopenia syndrome virus (SFTSV) infection status, we isolated SFTSVs from severe fever with thrombocytopenia syndrome (SFTS)-suspected patients in 207 hospitals throughout South Korea between 2013 and April of 2017. A total of 116 SFTSVs were isolated from 3,137 SFTS-suspected patients with an overall 21.6% case fatality rate. Genetic characterization revealed that at least six genotypes of SFTSVs are co-circulating in South Korea with multiple reassortments among them. Of these, the genotype B-2 strains were the most prevalent (n = 48, 36.1%) followed by the A and F genotypes. Clinical and epidemiologic investigations revealed that genotype B strains were associated with the highest case-fatality rate (34.8%, 32/92), while genotype A caused only one fatality out of ten patients. Further, ferret infection studies demonstrated varied clinical manifestations and case mortality rates of different strains of SFTSV, which suggests this virus could exhibit genotype-dependent pathogenicity.Keywords: severe fever with thrombocytopenia syndrome virus (SFTSV), clinical manifestations, genotypes, pathogenesis
Seok-Min Yun, Su-Jin Park, Young-Il Kim, Sun-Whan Park, Min-Ah Yu, Hyeok-Il Kwon, Eun-Ha Kim, Kwang-Min Yu, Hye Won Jeong, Jungsang Ryou, Won-Ja Lee, Youngmee Jee, Joo-Yeon Lee, Young Ki Choi
Despite an unprecedented 2 decades of success, the combat against malaria — the mosquito-transmitted disease caused by Plasmodium parasites — is no longer progressing. Efforts toward eradication are threatened by the lack of an effective vaccine and a rise in antiparasite drug resistance. Alternative approaches are urgently needed. Repurposing of available, approved drugs with distinct modes of action are being considered as viable and immediate adjuncts to standard antimicrobial treatment. Such strategies may be well suited to the obligatory and clinically silent first phase of Plasmodium infection, where massive parasite replication occurs within hepatocytes in the liver. Here, we report that the widely used antidiabetic drug, metformin, impairs parasite liver stage development of both rodent-infecting Plasmodium berghei and human-infecting P. falciparum parasites. Prophylactic treatment with metformin curtails parasite intracellular growth in vitro. An additional effect was observed in mice with a decrease in the numbers of infected hepatocytes. Moreover, metformin provided in combination with conventional liver- or blood-acting antimalarial drugs further reduced the total burden of P. berghei infection and substantially lessened disease severity in mice. Together, our findings indicate that repurposing of metformin in a prophylactic regimen could be considered for malaria chemoprevention.
Iset Medina Vera, Margarida T. Grilo Ruivo, Leonardo F. Lemos Rocha, Sofia Marques, Sangeeta N. Bhatia, Maria M. Mota, Liliana Mancio-Silva
Toll-like receptor 3 (TLR3) is a pathogen recognition molecule associated with viral infection with double-stranded RNA (dsRNA) as its ligand. We evaluated the role of TLR3 in bacterial pneumonia using Klebsiella pneumoniae (KP). WT and TLR3–/– mice were subjected to a lethal model of KP. Alveolar macrophage polarization, bactericidal activity, and phagocytic capacity were compared. RNA-sequencing was performed on alveolar macrophages from the WT and TLR3–/– mice. Adoptive transfers of alveolar macrophages from TLR3–/– mice to WT mice with KP were evaluated for survival. Expression of TLR3 in postmortem human lung samples from patients who died from gram-negative pneumonia and pathological grading of pneumonitis was determined. Mortality was significantly lower in TLR3–/–, and survival improved in WT mice following antibody neutralization of TLR3 and with TLR3/dsRNA complex inhibitor. Alveolar macrophages from TLR3–/– mice demonstrated increased bactericidal and phagocytic capacity. RNA-sequencing showed an increased production of chemokines in TLR3–/– mice. Adoptive transfer of alveolar macrophages from the TLR3–/– mice restored the survival in WT mice. Human lung samples demonstrated a good correlation between the grade of pneumonitis and TLR3 expression. These data represent a paradigm shift in understanding the mechanistic role of TLR3 in bacterial pneumonia.
Madathilparambil V. Suresh, Vladislav A. Dolgachev, Boya Zhang, Sanjay Balijepalli, Samantha Swamy, Jashitha Mooliyil, Georgia Kralovich, Bivin Thomas, David Machado-Aranda, Monita Karmakar, Sanjeev Lalwani, Arulselvi Subramanian, Arun Anantharam, Bethany B. Moore, Krishnan Raghavendran
Influenza is a highly contagious viral pathogen with more than 200,000 cases reported in the U.S. during the 2017-2018 season. Annual vaccination is recommended by the World Health Organization with the goal to reduce influenza severity and transmission. Currently available vaccines are ~60% effective and vaccine effectiveness varies from season to season, as well as between different influenza subtypes within a single season. Immunological imprinting from early life influenza infection can prominently shape the immune response to subsequent infections. Here, the impact of pre-existing B cell memory in the response to quadrivalent influenza vaccine was assessed using blood samples collected from healthy subjects (18 to 85 years old) prior to and 21-28 days following influenza vaccination. Influenza vaccination increased both HA-specific antibodies and memory B cells frequency. Despite no apparent differences in antigenicity between vaccine components, most individuals were biased towards one of the vaccine strains. Specifically, responses to H3N2 were reduced in magnitude relative to the other vaccine components. Overall, this study unveils a new mechanism underlying differential vaccine effectiveness against distinct influenza subtypes.
Rodrigo B. Abreu, Greg A. Kirchenbaum, Emily F. Clutter, Giuseppe A. Sautto, Ted M. Ross
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