Palliative surgery: state of the science and future directions

Palliative surgical procedures are operations that aim to alleviate symptoms in a patient with serious, life-limiting illness. They are common, particularly within the field of surgical oncology. However, few high-quality studies have attempted to measure the durability of improvements in symptoms and quality of life after palliative surgery. Furthermore, many of the studies that do exist are outdated and employ highly inconsistent definitions of palliative surgery. Consequently, the paucity of robust and reliable evidence on the benefits, risks, and trade-offs of palliative surgery hampers clinical decision-making for patients and their surgeons. The evidence for palliative surgery suggests that, with effective communication about goals of care and careful patient selection, palliative surgery can provide symptomatic relief and reduce healthcare burdens for certain seriously ill patients.

Clonally expanded γδ T cells protect against Staphylococcus aureus skin reinfection

The mechanisms that mediate durable protection against Staphylococcus aureus skin reinfections are unclear, as recurrences are common despite high antibody titers and memory T cells. Here, we developed a mouse model of S. aureus skin reinfection to investigate protective memory responses. In contrast with WT mice, IL-1β-deficient mice exhibited poor neutrophil recruitment and bacterial clearance during primary infection that was rescued during secondary S. aureus challenge. The γδ T cells from skin-draining LNs utilized compensatory T cell-intrinsic TLR2/MyD88 signaling to mediate rescue by trafficking and producing TNF and IFN-γ, which restored neutrophil recruitment and promoted bacterial clearance. RNA-sequencing (RNA-seq) of the LNs revealed a clonotypic S. aureus-induced γδ T cell expansion with a complementarity-determining region 3 (CDR3) aa sequence identical to that of invariant Vγ5+ dendritic epidermal T cells. However, this T cell receptor γ (TRG) aa sequence of the dominant CDR3 sequence was generated from multiple gene rearrangements of TRGV5 and TRGV6, indicating clonotypic expansion. TNF- and IFN-γ-producing γδ T cells were also expanded in peripheral blood of IRAK4-deficient humans no longer predisposed to S. aureus skin infections. Thus, clonally expanded γδ T cells represent a mechanism for long-lasting immunity against recurrent S. aureus skin infections.

An alternative mechanism for durable protective immunity to Staphylococcus aureus skin infection

The immune mechanisms for durable immunity against S. aureus skin infections are unclear as reinfections are common despite specific antibodies and Th1/Th17 cells. Using a CA-MRSA skin reinfection model in mice involving a primary infection (1°) in the lower back (cleared by 14 days) followed by a secondary infection (2°) in the upper back on day 28, we found that 1° and 2° wt mice had similar responses. In contrast, 1° IL-1β−/− mice had increased lesions and bacterial burden with impaired neutrophil recruitment whereas 2° IL-1β−/− mice were protected and resembled wt mice. Transfer of serum containing CA-MRSA specific antibodies did not confer protection to 1° IL-1β−/− mice and depletion of CD4+ T cells did not alter the protection of 2° IL-1β−/− mice, indicating a lack of a role of antibodies or CD4+ T cells. However, 2° IL-1β−/− mice were no longer protected if the egress of lymphocytes from lymph nodes was blocked in 2° IL-1β−/− mice (FTY720 treatment) and the immune impairment in naïve IL-1β−/− mice could be rescued by adoptive transfer of total lymph nodes cells from d28 IL-1β−/− mice. Moreover, transfer of only 50,000 γδ T cells from lymph nodes of day 28 IL-1β−/− mice conferred protection to 1° IL-1β−/− mice. These γδ T cells produced IFNγ/TNF-α, but not IL-17/IL-22, and neutralizing IFNγ/TNF-α activity resulted in loss of protection in 2° IL-1β−/− mice. In humans, similar IFNγ/TNF-α-producing γδ T cells were found in individuals with IRAK4 deficiency whose susceptibility to S. aureus skin infections improves with age but not from individuals with chronic granulomatous disease whose susceptibility is lifelong. These findings define an alternative mechanism to therapeutically target for long-term protection against CA-MRSA skin infections.