Background We previously reported that lymphocytopenia and T cell exhaustion is notable in acute COVID19 patients, especially in aged and severe cases. Thymosin alpha 1 (Tα1) had been used in the treatment of viral infections as an immune response modifier for many years. However, clinical benefits and mechanism of Tα1 supplement to COVID-19 are still unclear. Methods We retrospectively reviewed the clinical outcomes of 76 severe cases with COVID-19 admitted into two hospitals in Wuhan from December 2019 to March 2020. The thymus output in peripheral blood mononuclear cells (PBMCs) from COVID-19 patients was measured by T cell receptor excision circles (TREC). The levels of T cell exhaustion markers PD-1 and Tim-3 on CD8+ T cells were detected by flow cytometry. Results Compared with untreated group, Tα1 treatment significantly reduces mortality of severe COVID-19 patients (11.11% vs. 30.00%, p=0.044). Tα1 timely enhances blood T cell numbers in COVID-19 patients with severe lymphocytopenia (the counts of CD8+ T cells or CD4+ T cells in circulation lower than 400/μL or 650/μL, respectively). Under such conditions, Tα1 also successfully restores CD8+ and CD4+ T cell numbers in aged patients. Meanwhile, Tα1 reduces PD-1 and Tim-3 expression on CD8+ T cells from severe COVID-19 patients in comparison with untreated cases. It is of note that restoration of lymphocytopenia and acute exhaustion of T cells are roughly parallel to the rise of TRECs. Conclusions Tα1 supplement significantly reduce mortality of severe COVID-19 patients. COVID-19 patients with the counts of CD8+ T cells or CD4+ T cells in circulation lower than 400/μL or 650/μL, respectively, gain more benefits from Tα1. Tα1 reverses T cell exhaustion and recovers immune reconstitution through promoting thymus output during SARS-CoV-2 infection.

Background Penicillium marneffei (P. marneffei) is a thermally dimorphic fungus pathogen that causes fatal infection. Alveolar macrophages are innate immune cells that have critical roles in protection against pulmonary fungal pathogens and the macrophage polarization state has the potential to be a deciding factor in disease progression or resolution. The aim of this study was to investigate mouse alveolar macrophage polarization states during P. marneffei infection.ResultsWe used enzyme-linked immunosorbent (ELISA) assays, quantitative real-time PCR (qRT-PCR), and Griess, arginase activity to evaluate the phenotypic markers of alveolar macrophages from BALB/C mice infected with P. marneffei. We then treated alveolar macrophages from infected mice with P. marneffei cytoplasmic yeast antigen (CYA) and investigated alveolar macrophage phenotypic markers in order to identify macrophage polarization in response to P. marneffei antigens. Our results showed: i) P. marneffei infection significantly enhanced the expression of classically activated macrophage (M1)-phenotypic markers (inducible nitric oxide synthase [iNOS] mRNA, nitric oxide [NO], interleukin-12 [IL-12], tumor necrosis factor-alpha [TNF-α]) and alternatively activated macrophage (M2a)-phenotypic markers (arginase1 [Arg1] mRNA, urea) during the second week post-infection. This significantly decreased during the fourth week post-infection. ii) During P. marneffei infection, CYA stimulation also significantly enhanced the expression of M1 and M2a-phenotypic markers, consistent with the results for P. marneffei infection and CYA stimulation preferentially induced M1 subtype.ConclusionsThe data from the current study demonstrated that alveolar macrophage M1/M2a subtypes were present in host defense against acute P. marneffei infection and that CYA could mimic P. marneffei to induce a host immune response with enhanced M1 subtype. This could be useful for investigating the enhancement of host anti-P. marneffei immune responses and to provide novel ideas for prevention of P. marneffei-infection.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-017-1086-3) contains supplementary material, which is available to authorized users.

Penicillium marneffei is a thermally dimorphic pathogenic fungus that causes systemic infection similar to disseminated cryptococcosis. P. marneffei is endemic in Southeast Asia, usually infecting HIV-infected individuals; infection of HIV-negative individuals is extremely rare. Here, we describe a disseminated P. marneffei infection within an osteolytic lesion in an HIV-negative patient. A 40-year-old Chinese woman presented with intermittent fever, generalized lymphadenopathy, and a skin rash. Following a sternum biopsy, the patient was diagnosed with P. marneffei infection. An emission computed tomography bone scan revealed the presence of increased radioactivity in the left clavicle and sternum, indicative of an osteolytic lesion. In addition to reporting this very rare case, we also present a brief review of the literature, highlighting the differences in clinical manifestations between HIV-positive and HIV-negative patients infected with P. marneffei as it applies to our case.