Digenic Inheritance: Evidence and Gaps in Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory disorder characterized by the inability to properly terminate an immune response. Familial HLH (FHLH) and related immune dysregulation syndromes are associated with mutations in the genes PRF1, UNC13D, STX11, STXBP2, LYST, AP3B1, and RAB27A, all of which are required for the assembly, exocytosis, and function of cytotoxic granules within CD8+ T cells and natural killer (NK) cells. Loss-of-function mutations in these genes render the cytotoxicity pathway ineffective, thereby failing to eradicate immune stimuli, such as infectious pathogens or malignant cells. The resulting persistent immune system stimulation drives hypercytokinemia, ultimately leading to severe tissue inflammation and end-organ damage. Traditionally, a diagnosis of FHLH requires the identification of biallelic loss-of-function mutations in one of these degranulation pathway genes. However, this narrow definition fails to encompass patients with other genetic mechanisms underlying degranulation pathway dysfunction. In particular, mounting clinical evidence supports a potential digenic mode of inheritance of FHLH in which single loss-of-function mutations in two different degranulation pathway genes cooperate to impair pathway activity. Here, we review the functions of the FHLH-associated genes within the degranulation pathway and summarize clinical evidence supporting a model in which cumulative defects along this mechanistic pathway may underlie HLH.

Ghee Butter from Bovine Colostrum Reduces Inflammation in the Mouse Model of Acute Pancreatitis with Potential Involvement of Free Fatty Acid Receptors

Acute pancreatitis (AP) is an inflammatory disease that causes severe tissue damage. Ghee butter from bovine colostrum (GBBC) is a clarified butter produced by heating milk fat to 40 °C and separating the precipitating protein. As colostrum mainly contains fatty acids (FAs), immunoglobulins, maternal immune cells, and cytokines, we hypothesized that it may exert anti-inflammatory effects. We investigated the effects of GBBC on experimental AP in mice. Two intraperitoneal (ip) injections of L-arginine (8%) were given 1 h apart to generate the AP murine model. After 12 h from the first L-arginine injection, mice were divided into the following experimental groups: AP mice treated with GBBC (oral gavage (po) every 12 h) and non-treated AP mice (po vehicle every 12 h). Control animals received vehicle only. At 72 h, mice were euthanized. Histopathological examination along with myeloperoxidase (MPO) and amylase/lipase activity assays were performed. In a separate set of experiments, FFAR1 and FFAR4 antagonists were used to verify the involvement of respective receptors. Administration of GBBC decreased MPO activity in the pancreas and lungs along with the microscopical severity of AP in mice. Moreover, treatment with GBBC normalized pancreatic enzyme activity. FFAR1 and FFAR4 antagonists tended to reverse the anti-inflammatory effect of GBBC in mouse AP. Our results suggest that GBBC displays anti-inflammatory effects in the mouse model of AP, with the putative involvement of FFARs. This is the first study to show the anti-inflammatory potential of a nutritional supplement derived from GBBC.

Horn bud size of dairy-bred and suckler-bred calves at time of disbudding

Background Hot-iron disbudding is a common management procedure to prevent horn growth in calves. The study objective was to examine effect of age, breed and sex on horn bud size of dairy-bred and suckler-bred calves at time of disbudding. Results The left and right horn bud size (diameter and height in mm) of 279 calves, including dairy-bred Holstein-Friesian (Male (M) = 88) and 191 suckler-bred (86 Charolais, CH; (M = 39, Female (F) = 47), 67 Limousin, LM; (M = 32, F = 35) and 38 Simmental, SI; (M = 22, F = 16) sired)) was measured using a digital calliper at time of disbudding. Calves were retrospectively assigned to two age categories at time of disbudding: 1), 14 to 28 days (d) old and 2), 29 to 60 d old. Holstein-Friesian M calves had a greater horn bud diameter (16.97 v.14.45 mm) and height (7.79 v. 5.00 mm) compared to suckler-bred M calves (P < 0.01), with no difference (P > 0.05) among the suckler-bred calves. Suckler-bred M calves had a greater horn bud diameter (14.46 vs 13.29 mm) and height (5.01 vs 3.88 mm) compared to suckler-bred F calves (P < 0.05). The slopes of the lines of best fit show that horn bud diameter and height increased with age (P < 0.05) for HF, SI male and CH female calves while there was no relationship with age (P > 0.05) for CH and LM male calves, or for SI and LM female calves. Linear regression of age with diameter and with height for each breed and sex showed high variability in the data as indicated by R-squared values ranging from 0.003–0.41 indicating that in the case of the diameter and the height, the weight of the fitting effect was poor. Conclusions Calf age is not a good predictor of horn bud size and recommendations for the disbudding of calves should be based on horn bud size and not on age. The implications of these findings are that calves should be disbudded while horn development is still at the bud stage and when the bud is large enough to be easily palpable/visible, but not so large that disbudding could lead to severe tissue trauma.

Insights Into Host Cell Cytokines in Chlamydia Infection

Chlamydial infection causes a number of clinically relevant diseases and induces significant morbidity in humans. Immune and inflammatory responses contribute to both the clearance of Chlamydia infection and pathology in host tissues. Chlamydia infection stimulates host cells to produce a large number of cytokines that trigger and regulate host immune responses against Chlamydia. However, inappropriate responses can occur with excessive production of cytokines, resulting in overreactive inflammatory responses and alterations in host or Chlamydia metabolism. As a result, Chlamydia persists and causes wound healing delays, leading to more severe tissue damage and triggering long-lasting fibrotic sequelae. Here, we summarize the roles of cytokines in Chlamydia infection and pathogenesis, thus advancing our understanding chlamydial infection biology and the pathogenic mechanisms involved.

SARS-CoV-2 Induces Lymphocytopenia by Promoting Inflammation and Decimates Secondary Lymphoid Organs

While lymphocytopenia is a common characteristic of coronavirus disease 2019 (COVID-19), the mechanisms responsible for this lymphocyte depletion are unclear. Here, we retrospectively reviewed the clinical and immunological data from 18 fatal COVID-19 cases, results showed that these patients had severe lymphocytopenia, together with high serum levels of inflammatory cytokines (IL-6, IL-8 and IL-10), and elevation of many other mediators in routine laboratory tests, including C-reactive protein, lactate dehydrogenase, α-hydroxybutyrate dehydrogenase and natriuretic peptide type B. The spleens and hilar lymph nodes (LNs) from six additional COVID-19 patients with post-mortem examinations were also collected, histopathologic detection showed that both organs manifested severe tissue damage and lymphocyte apoptosis in these six cases. In situ hybridization assays illustrated that SARS-CoV-2 viral RNA accumulates in these tissues, and transmission electronic microscopy confirmed that coronavirus-like particles were visible in the LNs. SARS-CoV-2 Spike and Nucleocapsid protein (NP) accumulated in the spleens and LNs, and the NP antigen restricted in angiotensin-converting enzyme 2 (ACE2) positive macrophages and dendritic cells (DCs). Furthermore, SARS-CoV-2 triggered the transcription of Il6, Il8 and Il1b genes in infected primary macrophages and DCs in vitro, and SARS-CoV-2-NP+ macrophages and DCs also manifested high levels of IL-6 and IL-1β, which might directly decimate human spleens and LNs and subsequently lead to lymphocytopenia in vivo. Collectively, these results demonstrated that SARS-CoV-2 induced lymphocytopenia by promoting systemic inflammation and direct neutralization in human spleen and LNs.

Advanced Strategies for Tissue Engineering in Regenerative Medicine: A Biofabrication and Biopolymer Perspective

Tissue engineering is known to encompass multiple aspects of science, medicine and engineering. The development of systems which are able to promote the growth of new cells and tissue components are vital in the treatment of severe tissue injury and damage. This can be done through a variety of different biofabrication strategies including the use of hydrogels, 3D bioprinted scaffolds and nanotechnology. The incorporation of stem cells into these systems and the advantage of this is also discussed. Biopolymers, those which have a natural original, have been particularly advantageous in tissue engineering systems as they are often found within the extracellular matrix of the human body. The utilization of biopolymers has become increasing popular as they are biocompatible, biodegradable and do not illicit an immune response when placed into the body. Tissue engineering systems for use with the eye are also discussed. This is of particular interest as the eye is known as an immune privileged site resulting in an extremely limited ability for natural cell regeneration.

Changes of the Blood Lymphocytes On Severe Trauma Patients in Early Time

Purpose: To evaluate the relationship between the change of blood lymphocyte counts in early stages of trauma patients and the secondary tissue injury after trauma. Method: A retrospective study was conduct to include trauma patients with Injury Severity Score(ISS) ≥16 between January 1 st , 2018 and December 31 st , 2019. Lymphocyte counts of each trauma patient were collected and recorded in first 3 hours, 6-12 hours, 24-48 hours, and 49-72 hours after trauma, separately. The degree of secondary on the trauma patients were evaluated according to the results of laboratory tests, the time stay in ICU and received mechanical ventilation, and 28-day outcome. Correlation analysis was performed between lymphocytes change and the score of the secondary tissue injury in severe trauma patients. Results: The lymphocyte count within first 3 hours after trauma was significantly high,the median was 4.03×10 9 /L, then dropped significantly in 6-72 hours after trauma (median: 0.85~0.99×10 9 /L), there was a significant statistical difference between the lymphocyte count within first 3 hours after trauma and that in 6-72 hours（P=0.000). The ratios of the lymphocytes counts in 6-72 hours to that within first 3 hours after trauma were very low, the median value was 0.22-0.27. The results of regression statistical analysis showed that the change of lymphocyte counts significantly associated with the severe degree of secondary injury (P=0.000). The lymphocyte ratio change can be used to predict the possibility of trauma patients secondary severe tissue injury occurred [Area Under the Curve( AUC) on the ratios of the lymphocytes counts in 6-72 hours to that within first 3 hours after trauma was 0.789, 0.840, 0.861, respectively]. The predictive thresholds of lymphocyte ratio of the trauma patients in the study were 0.31 to 0.35, the prediction sensitivity were 78% to 89% and specificity 74% to 84%. The lymphocyte counts there was significant difference between the patients with assessed as serious secondary tissue injury(87cases) and patients without(25 cases), the median value was 0.21-0.24 , 0.38-0.62, respectively , P=0.000. Conclusion: Lymphocytes counts was significantly increased in the trauma patients with ISS score ≥16 within the first 3 hours after trauma, then decreased significantly in 6-72 hours after trauma. The change of lymphocyte count was significant relationship with the degree of secondary tissue injury, that can be used to predict the degree of secondary severe tissue injury occurred by inflammatory reaction in trauma patients.