Long-term antibody responses and neutralizing activities following SARS-CoV-2 infections have not yet been elucidated. We quantified immunoglobulin M (IgM) and G (IgG) antibodies recognizing the SARS-CoV-2 receptor-binding domain (RBD) of the spike (S) or the nucleocapsid (N) protein, and neutralizing antibodies during a period of six months following COVID-19 disease onset in 349 symptomatic COVID-19 patients, which were among the first world-wide being infected. The positivity rate and magnitude of IgM-S and IgG-N responses increased rapidly. High levels of IgM-S/N and IgG-S/N at 2-3 weeks after disease onset were associated with virus control and IgG-S titers correlated closely with the capacity to neutralize SARS-CoV-2. While specific IgM-S/N became undetectable 12 weeks after disease onset in most patients, IgG-S/N titers showed an intermediate contraction phase, but stabilized at relatively high levels over the six months observation period. At late time points the positivity rates for binding and neutralizing SARS-CoV-2-specific antibodies was still over 70%. Taken together, our data indicate sustained humoral immunity in recovered patients who suffer from symptomatic COVID-19, suggesting prolonged immunity.

The number of coronavirus disease 2019 (COVID-19) cases has exceeded 10 million. However, little is known about the epidemiology and clinical characteristics of COVID-19 infants. We collected medical information of 46 confirmed patients (<1 year old) and retrospectively analyzed epidemiological history, clinical symptoms, and laboratory test results. The median age was 5 (interquartile range, 2–7) months. Sixteen cases had fever and 27 cases had cough. Moderate disease was present in 40 cases and cardiac injury occurred in 38 cases, following by liver dysfunction in 20 cases and lymphopenia in no cases. Of all infant patients, 2 received invasive mechanical ventilation and 1 died with multiple organ dysfunction syndrome.

Purpose: Klebsiella pneumoniae-caused pneumonia is a risk factor for development of lung injury. However, the current clinical isolates of K. pneumoniae are mostly multidrug-resistance and thus must be addressed with new treatments. One ideal approach is to enhance the innate immunity of the infected host through metabolic modulators. Materials and Methods: We used GC/MS-based metabolomics to profile the metabolomes among Control, Dead and Survival groups. The key metabolites were administrated in mice, and the bacterial loads in lung and survival were measured. The effect of the key metabolites on macrophage phagocytosis was determined by flow cytometry. Results: Compared with the mice that compromised from K. pneumoniae lung infection, mice that survived the infection displayed the varied metabolomic profile. The differential analysis of metabolome showed D-Glucose, Glutamine, L-Serine, Myo-inositol, Ethanedioic acid and Lactic acid related to the host surviving a K. pneumoniae lung infection. Further pathway enrichment analysis proposed that valine, leucine and isoleucine biosynthesis involved in outcome of lung infection. The follow-up data showed that exogenous L-Serine, L-Valine and L-Leucine could decline the load of K. pneumoniae in infected lung and increases the mouse survival. More interestingly, L-Serine, L-Valine and L-Leucine also were able to promote macrophage phagocytosis that is the natural way to promote hosts to clear lung pathogens. Conclusions: Our study establishes a novel strategy of identifying metabolic modulator from surviving host and emphasizes the feasibility of employing the metabolic modulator as a therapy for K. pneumoniae lung infection.

Introduction: Postmenopausal osteoporosis (PMOP) is a common chronic disease, and the loss of bone density and bone strength after menopause are its main symptoms. Effective treatments for PMOP are still uncertain, but Chinese medicine has some advantages in slowing down bone loss. Shengu granules are often used clinically to treat PMOP. It has been shown to be an effective prescription for the treatment of PMOP, and there is evidence that gut flora may play an important role. However, whether Shengu granules attenuate PMOP by modulating gut flora and related mechanisms remains unclear.Methods: In this study, we mainly examined the bone strength of the femur, the structure of the intestinal microbiota, SCFAs in the feces and the level of FOXP3 cells in the colon. To further learn about the inflammation response, the condition of the mucosa and the level of cytokines in the serum also included in the testing. In addition, to get the information of the protein expression, the protein expression of OPG and RANKL in the femur and the protein expression of ZO-1 and Occludin in the colon were taken into account.Results: The osteoporosis was significantly improved in the SG group compared with the OVX group, and the diversity of intestinal flora, the secretion level of SCFAs and the expression level of FOXP3 were significantly increased compared with the OVX group. In terms of inflammatory indicators, the intestinal inflammation scores of the SG group was significantly lower than those in the OVX group. Additionally, the serum expression levels of IL-10 and TGF-β in the SG group were significantly increased compared with the OVX group, and the expression levels of IL-17 and TNF-α were significantly decreased compared with the OVX group. In terms of protein expression, the expression levels of ZO-1, Occluding and OPG were significantly increased in the SG group compared with the OVX group, and the expression level of RANKL was significantly decreased compared with the OVX group.Discussion: Shengu granules treatment can improve the imbalance of intestinal flora, increase the secretion of SCFAs and the expression of FOXP3, which reduces the inflammatory response and repairs the intestinal barrier, as well as regulates the expression of OPG/RANKL signaling axis. Overall, Shengu granules ameliorate ovariectomy-induced osteoporosis by the gut-bone-immune axis.

To explore the expansion and differentiation of hepatocytoid cell induced from myeloid mesenchymal stem cell (MSC) in vitro, in order to find suitable resource of hepatocytes for bioartificial liver or liver transplantation. The rat myeloid MSC was isolated and divided into three groups which were cultured by Friedensteion method, and then were induced by culture fluid, culture fluid plus cholestatic serum and culture fluid plus hepatocyte growth factor (HGF), respectively. Hepatocytoid cell as well as expression of CK18 and AFP was observed by immunohistochemistry. After the induction for 21 d, hepatocytoid cell was observed, and its expression of CK18 and AFP was detected by immunohistochemistry in MSC cultured with cholestatic serum. Furthermore, on the 35th d, albumin mRNA was expressed in the cell, suggesting the inducing effect was similar to that by HGF. Rat myeloid MSC can differentiate into hepatocyte lineage under appropriate condition. This method is easy to operate.